Wolfgang Pauli predicted the existence of the neutrino, which was later found to explain the loss of energy during decay.
Antineutrinos are a form of antimatter.
Every known particle has an antiparticle.
Particles such as the positron and their funda mental interactions are investigated in this chapter.
By the end of this chapter, you will be able to understand the physics behind PET and the basic components of the universe.

The word "atom" means indivisible.

Physicists used to think that atoms were the smallest part of matter.
The internal structure of atoms was discovered in the late 19th century.
The discovery of radioactivity showed that the nucleus has a complex structure.
The investigation of black body radiation, photoelectric effect, and Compton scattering led scientists to conclude that light can be modeled as a photon.
Physicists identified four particles by 1930.
The proposal and discovery of so-cal ed antiparticles changed this view.

Ein stein's theory of special relativity was incorporated into quantum mechanics by Paul Dirac.

Dirac's model was able to predict the spin quantum number for the electron.
An unexpected com plication came along with this prediction.
Dirac's model predicted that free electrons had an infinite number of quantum states with negative total energy.
A free electron in a positive energy state should be able to transition to one of the nega tive energy states by emitting a photon.
All free electrons in the universe would transition to increasingly negative energy states.
This is not consistent with the behavior of electrons.

Dirac suggested that the negative energy states were occupied by a finite number of virtual electrons.

According to the Pauli exclusion principle, free electrons with positive energy can't transition into states that are electron states.

Dirac proposed that one of the virtual electrons in a negative energy state could be lifted out of its negative energy state and become a positive energy free electron.

Many quantum physicists disagreed with his model.
Dirac argued that the particles should exist.

Scientists used cloud chambers to determine the direction of the force that the mag netic field would exert on a positron.

The chamber was filled with a gas that was supersaturated with water or alcohol.

The cloud chamber was placed in a magnetic field.

The plane of the page was pointed into by the magnetic field.

The direction of travel of the particle was not immediately apparent.

It must be a negatively charged particle in order to curve if it entered the chamber from the top.
It must be a positively charged particle if it entered the chamber from the bottom.

The lower part of the path is less curved than the upper part.

The path was caused by a cular path.

The particle's speed decreased.

The positive charged particle must have traveled from the bottom of the chamber to the top.

If the path was caused by Anderson, the charge-to-mass ratio of the par- a positron moving from the bottom to the top ticle was the same as for an electron.

The cloud chamber trace must have been produced by one of Dirac's antielectrons.

There are few positrons in our world.

Positrons exist for very short periods.

During the interaction of a high-energy photon with matter, Positrons can be produced.

The photon cannot exist at rest, so you can't be sure of its mass on a scale.

The photon can produce both an electron and a posi at the same time.

We assume the spiral circles for the minimal energy calculation.

The wavelength is about 100 times the wavelength of an X-ray photon.

If the positron and electron produced are to possess some energy, then a higher energy gamma ray is needed.

The two particles should spiral in opposite directions if they occur in a magnetic field.

The photon no longer exists, so the momentum of the two particles should be the same as the original photon.

If we place the system in a magnetic field, the field exerts a force on the electron and on the positron in opposite directions.

They should spiral in opposite directions because of the force that the field exerts on them.
As their speeds decrease, the radius of their circular paths should decrease as well.

We now know that high-energy rays can be used to create electron-positron pairs.

Imagine that an electron and a positron meet and anni- be constant.

They must travel in opposite directions as they move towards each other.
There will be one or two in the figure.

This process requires a reaction equation.

S g is converted into two gamma rays.

The system must remain constant in this pair.

An electron-posi Electric charge is constant in both versions of the pro-tron pair.

The momentum of the photon process is not conserved.

There was a previous exercise that involved a positron.

We discussed the creation of a positron and an electron by a high-energy photon as well as the production of positrons by radioactive decay.
Let's look at another possibility.
There is an explanation of the decay of a neutron in nuclear physics.
A free neutron has a half life of about 10 minutes.

The electric charge of the system during this process is constant at 10 + 1 + 2.

The system's energy can be constant because the rest energy of the neutron is greater than the rest energy of the electron and protons.
An appropriate combination of the momenta of the three particles in the final state can equal the initial momentum of the system.
This process can happen without being in contact with the environment.

Since the rest energy of the neutron is greater than the rest energy of the pro ton, it seems that it can't be turned into a neutron.

The photon is absorbed by the protons and it decays into a quark, a positron, and a neutrino.

Without the proton absorbing a photon, decay can occur.

If some of the nucleus's energy is converted into the rest of the products, it can happen inside.
Carbon-11, nitrogen-13, oxygen-15, fluorine-18, and potassium-40 are examples of nuclei that can undergo decay.

In the process of becoming an argon nucleus, the potassium nucleus emits a positron and a neutrino.

Bananas are a good source of the potassium-40 nuclei in your body.

Posirons produced by this radioactive decay travel infinitesimal distances.

They are attracted to nega tively charged electrons and produce high-energy gamma rays, most of which leave the body.
This is the process that makes positron emission tomography possible.

Positron emission tomography is described in the chapter opening.

Pro ducing positrons is a function of the decay of the isotopes.

The detectors produce a pair of rays that move in opposite directions.

A three-dimen sional image of the active parts of the brain is created by combining many pairs of gamma rays.

The brain is active when a person performs a particular task.

Other particles have anti particles as well.

The negatively charged antiproton of the same mass as the positively charged one is part of the nucleus.
The antimatter counterpart of the neutron has other properties besides charge that it ate from the antineutron.
The photon is an example of an ally.
In this chapter, we look at why our universe is made of mostly ordinary particles.

We have learned about many types of interactions in our studies of physics.

In terms of fundamental interactions, nonfundamental interactions can be understood.
Friction is a representation of the interaction between the electrons of the two surfaces.
When speaking in general terms, we use the term "Interaction" rather than "force" because interactions can be repre sented using energy ideas.
The four fundamental interactions are the gravita tional interaction, the electromagnetic interaction, the strong interaction and the weak interaction.

If the objects are in motion with respect to each other, the interaction is electric.

The interaction is magnetic if the objects are moving in the same direction.
The inverse square of the distance between the two charged particles decreases the interaction between them.
Understanding the structure of atoms is dependent on the netic interactions between nuclei and electrons.

Because they are composed of charged particles, atoms participate in elec tromagnetic interactions with each other.

The formation of molecule and holding of liquids andsolids are contributed to by these interactions.

Atomic nuclei are made up of protons that repel each other and of neutrons that don't exert any force.

The force of attraction is greater than the force of attraction.

Pro tons and neutrons only exert their power on their nearest neighbors within the nucleus, which is a range of 3 to 10 m.

The interaction is weak.

Think of an analogy.

Humans use speech.

A sound wave travels through the air to another person when a person's larynx vibrates.
The sound waves hurt the other person's ears.
The electrical signal travels to the brain, where it is interpreted.

The field model for the interactions between electrical and charged objects was developed earlier in the text.

The idea was that charged particles would cause an electric field around them.
When a charged particle moves, the "signal" produced by that movement ripples through the electric field at a finite speed, and only when that signal reaches other charged particles does the force on them by the field change.

The field model we used to explain the mechanism behind the mag netic interaction predicted the existence of waves of visible light.

We showed how the model of netic waves could be used to explain the photo electric effect.

Physicists realized during the first half of the 20th century that the photon played a more central role.

The exchange of photon between electrical and charged particles is the mechanism behind the phe nomena.

The particle exchange mechanism has been successful in descri bing the weak and strong interactions, and it has had some success in describing the gravitational interaction.

When two particles interact, one emits a particle that is absorbed by the other, in each of the four fundamental interactions.
The photon is used in teraction.
Two electrons repel each other because one emits a photon, which travels at light speed to the other electron, where it is absorbed.
The absorbing electron recoils when the photon is absorbed.

There appears to be a serious problem with the particle exchange mechanism.

This helps us understand how the particle works.

The energy of an atomic-scale system can vary from instant to instant.

The mediator photons are called virtual because they are only small energy fluctuations in the system.

They don't have independent energy of their own that could cause a chemical change in your eye or an electronic detector.
Virtual particles can't be detected directly in any way.

The total energy of the interactions should be low.

We can now think of four fundamental interactions as ex change processes of four different mediators.

The strong and weak interactions have been discovered.
The four types of interaction mediators are summarized.

The interaction can be modeled as a photon exchange.

Massless particles travel at the speed of light.
The photon and anti photon are the same particle.

Gluons have zero electric charge and interact strongly with each other.

The strong interac tion has a short range.
There are different types of gluons.
The interaction of quarks is made possible by the ex change of gluons.

The interaction is weak because of three particles.

It is its own antiparticle.

The existence of these particles was predicted by a theory in the 1960s.
There were no particles found at the European Orga nization for Nuclear Research.

The theory predicted that the mediators have a large rest energy.

Producing them required the colliding particles to have high total energy.
protons and antiprotons were only accelerated to energies of tens of giga-electron volts, which was below the rest energy of the weak interaction mediators.

Technology had to catch up to confirm the existence of the mediators.

The graviton is predicted to travel to the photon at the speed of light, but the assumptions about what a quantum theory of gravity should be are incorrect.

The mass of a protons is what distinguishes them.

It has a mass of about 100 times that of a protons.

The mass explains why the interaction is short.
Even if they travel at a light speed, they can only travel an average of 10-18 m.

The interaction mediators were listed in kilo grams.

The values are so small in particle physics that this is not a common practice.
Mass is not usually used.
The 2 were measured in eV.
The mega-electron volt 11 MeV is the range for typical particle "masses".

1 eV equals 10-19 J.

The mass in mega ticles is determined by the number of electron volts and the number of protons.

Physicists have been discovering new particles using particle accelerators since the early 20th century.

The properties of these particles can be determined.
The particles are not stable.
Stable particles remain until they decay into other particles.

The mechanism behind the four fundamental interactions are the interaction mediators.

One cat egory of particles.

The weak, electromagnetic, and weakly interacting latinos interact through the weakly interacting latinos.

The electron neutrino is neutral.
The particles form a family of leptons.

The first member of a second generation was discovered in 1936.

The electron and the three neutrinos are stable particles.

Until 1998 physicists had no evidence to suggest that the neutrinos were anything other than zero.

The process is only possible if the neutrinos have zero mass.
Evidence from both particle physics and astrophysics shows that the three neutrinos have a rest energy of about 1 eV.
Experiments are being conducted to measure this more precisely.
They are difficult to detect because they don't interact via the strong interaction.

There are more examples of baryons than you know.

The lambda particle 0 and a set of four similar baryons known as the delta particles -, 0, +, and ++ were discovered in 1949-1952.
There were more baryons discovered in later years.

The first example of a meson was Hideki Yukawa's suggestion in 1935.

These particles were called mesons.
Combining rel ativity theory with quantum theory was the motivation for Yukawa's ideas.
The mass of Yukawa's mesons were 888-276-5932 888-276-5932 888-276-5932 888-276-5932s.
The correct properties of Yukawa's meson were discovered in 1947 by physicists, who called it a pi-meson or pion.

The internal structure of baryons and mesons is discussed in the next subsection.

The hadrons are not stable.
Their half-lives range from 610 s for the neutron to 24 s for the shortest lived.
Since 1950, hundreds of hadrons have been discovered.

The three quarks were caused by the large number of hadrons and the differences in their properties.

A new model of hadrons was independently proposed by Electron and his colleagues.

The hadrons are complex objects made of a small number of more fundamental particles that combine in different combinations to make all of the existing hadrons.

The elements of the periodic table can be made using different combinations of protons, neutrons, and electrons.

Experiments in which electron beams with energies of 25 GeV were shot into a sample of liquid hydrogen were explained by the idea of hadrons having internal structure.

The alpha particles shot by Rutherford's colleagues at gold foil atoms were similar to the scattered electrons.

The particles had to be charged with electricity.

The quark model only required three quarks to build hadrons.
There are now six quarks, all of which have been discov ered.

The quarks act weakly because they have nonzero mass.

Bars and mesons are bound states of three quarks and one antiquark, respectively.

There are three generations of leptons, each with a negatively charged member and a neutrino, for a total of six lep tons.

For a total of six quarks, the quarks fall into three generations.
There is a connection between the quarks and the leptons.

Particles have certain properties that determine whether they participate in certain interactions.

There are objects with zero electric charge.
It is not related to the colors we see with our eyes, but rather is a technical term that is used as a name for this property.
quarks have color charge because they participate in strong interaction A particle with a color charge can interact with another particle.

The neutral atoms have a net electric charge of zero and the particles that make up the protons and neutron are made of three quarks with different colors.

A protons has one red quark, one blue quark, and one green quark.

The effect of shining complimentary beams of red, blue, and green light on a surface is similar to this neutrality.

The surface glows white when it is color neutral.

quarks have a fractional electric charge.

There are two up quarks and one down posed of three quarks.

If down quark were converted to an up quark, this would be accomplished.

This sounds like one up and two down quarks.

The net charge is neutral.

An antineutron has properties besides charge that make it dif ferentiate from a neutron.

One up antiquark and two down antiquark make up an antineutron.

Our local world is made of electrons and two types of quarks.

There has never been an experiment that produced a quark in isolation.

The quark and the Tiquark have always been part of a hadron.
Attempting to split a protons into quarks by shooting a high-energy particle into it produces more quark-antiquark pairs.
New baryons and mesons are formed when these pairs combine with the original protons.
The strongest interaction is when the quarks are close together.
The reasons for the strong interaction ex hibits confinement are beyond the scope of this book, but the feature is crucial to explaining the structure and stability of the protons and neutrons in every atomic nucleus in your body.

The first versions were constructed in the first half of the 20th century.

The idea of special relativity and quantum mechanics were combined into a single model by physicists in the late 1940s.

The framework needed to describe the model was developed by Chen-Ning and Robert.

Several striking predictions were made by this model.

When the universe was smaller and hotter, all particles were massless.
As the universe cooled, it was predicted that the Higgs particle would interact with other particles, reconfiguring them into the form they are today.

Results from the first experiments began arriving at the end of 1974.

A meson composed of one charm and one anticharm quark.
The prediction of the J-psi particle was a success.

Scientists discovered the tau lepton and bottom quark between 1976 and 1979.

The top quark was discovered in the 1990s, and the tau 1096 Chapter 29 particle physics was discovered in 2000.

The discovery of a particle that may be the long-sought-after Higgs particle was announced in July of 2012

There is more work to be done to determine if the particle is the lightest of a series of Higgs particles predicted by theories that go beyond the Standard Model.

The matter of the universe is made up of quarks and leptons.

The quarks are in four fundamental interactions.
The strong interaction is what the leptons participate in.

There is a theory of strong interactions.

Some of the fundamental particles have nonzero mass because of the Higgs particle.

The Standard Model does not include the interaction.

How to combine this interaction with the Standard Model is a very challenging problem in physics.

Explain as many differences as you can between a protons and an electron using what you have learned about particle physics.

Almost all elementary particles have antiparticles.

The universe is expanding because distant galaxies are moving away from us.

The universe would get smaller, denser, and hotter if we reversed the expansion.

The universe would have been in a very hot and dense state a long time ago.

The model explained the red shifts of spiral nebulae.

The red shifts were greater for more distant nebulae.
The history of the universe is summarized below.

The average temperature of the universe was 1032 K at that time.

The temperature of the universe was about 1028 K. The volume of the universe increased by a factor of 1026 and settled into a more gradual expansion.
The density of the universe decreased during inflation.
The seeds of galaxy formation would later be found in areas where the density was slightly above average.

The density of the universe at a particular point differed from the average by only 1%.

The universe was made of hot particles.

The average temperature was so high that the random thermal motion of particles was very close to light speed.

There was a small excess of quarks over antimatter during this time because processes favored the production of matter over antimatter.
Understanding the details of these processes is an important goal of physics research.

The universe had cooled so much that quarks and gluons were able to form baryons.

There was an excess of quarks over antiquarks.
The temperature was not high enough to create antiproton pairs.
The baryons and antibaryons destroyed each other, leaving a small number of baryons.
Only one in 10 billion protons survived.
These are the protons that are found in the universe.
The thermal motion of particles was no longer relativistic after this.

The average density of the universe was close to sea level by a few minutes after the Big Bang, and the temperature had dropped to about a billion degrees K. For the first time, protons and neutrons were able to combine to form the simplest nuclei: deuterium, helium, and trace amounts of lithium.

Most of the protons were free as hydro Gen nuclei.

There was a ratio of hydrogen to helium nuclei.

The universe became cold enough for electrons to combine with nuclei to form neutral atoms.

The universe became transparent when this happened.
Prior to this, the uni verse was a plasma, an ionized gas of nuclei and electrons.
The particles do not travel freely.
The neutral atoms were able to travel freely when the universe was transparent.
The expansion of the universe has caused the red-shifted photons to have an effective temperature of about 2.7 K.

The ambient temperature of the present universe can be thought of as this.

The discovery of the CMB by Arno Penzias and Robert Wilson in 1965, was one of the most significant pieces of supporting evidence.

The model predicted the existence of this radiation.
Predicting the relative abundances of hydrogen, he lium, and lithium were made by the model.
Experiments are consistent with these predictions.

The dominant driver of the evolution was the interaction between the universe and the stars.

Some regions began contracting because of density fluctuations.
The formation of the first galaxies and stars happened 500,000 years after the Big bang.
Nuclear fusion processes produced heavier elements such as carbon, oxygen, iron, and gold, which were re leased into space to become planets.

The quarks that were part of the early universe are present on Earth.

During the life cycles of stars, the quarks formed complex nuclei and atoms.
Our bodies are composed of matter that was cre ated near the dawn of time and processed in stellar explosions before being part of us.

Two serious problems with the universe have yet to be solved in the 20th century.

The way stars move within them isn't explained by the size of the galaxies.
The universe is speeding up rather than slowing down, as the gravational interaction would predict.

In Chapter 4 we learned that Earth's speed around the Sun is deterred by the mass of the Sun.

The solar system's speed around the galaxy is determined by the total mass of everything that lies between the center of the galaxy and the center of the solar system.

There is too little visible mass to account for the motion of the galaxies relative to each other.

The observed motion of stars and galaxies is not being accounted for by the universe.

The first evidence of the problem was found in 1933 when astrophysicists looked at the Coma cluster.

The galaxies at the edge of the cluster were too fast to remain part of the clus ter.

Vera Rubin presented more evidence in the 70s.

She found that stars near the edge of a galaxy were traveling too fast to remain part of the galaxy.
The dark matter explanation began to become more accepted.

Scientists created experiments to detect a new form of unseen matter.

Direct detection of dark mat ter has not been accomplished.
Astronomers are more certain about what dark matter is than they are about what it is.
This is why it is cal ed "dark".
Dark matter can't be a dark cloud of protons or gaseous atoms because of the scattering of radiation passing through them.
There are several hypotheses for what this dark matter might be.
The names MACHOs and WIMPs are weakly acting massive particles.

These objects could be black holes, neutron stars, or brown dwarfs, which were not massive enough to achieve nuclear fusion and become stars.

Astronomers have been able to detect MACHOs using their effects on the light from distant ob jects.
When a MACHO passes in front of a distant object, the light bends around the MACHO and is focused for a short time, making the light appear brighter.
Over the course of 6 years, the MACHO Project has observed about 15 lensing events.
There must be more than one explanation.

In nature, these objects are more exotic.

The quarks and leptons that make up ordinary matter are not elementary particles.
Light is not absorbed or emitted by them and they are weak interacting.
Their mass is not zero.
neutrinos, axions, and neutralinos are not Standard Model particles and therefore need the Standard Model to be extended to accommodate them.

There are a lot of neutrinos in the universe.

The Standard Model does not give a zero mass to the neutrinos.
neutrinos have a rest energy range of 0.1 to 1.0 eV, a mil lion times smaller than the electron, according to recent experiments.
The dark matter was hoped to be if the neutrinos had enough mass.
It looks like neutrinos are too light for this.
Physicists don't know how to detect such a particle, but if it exists in sufficient abundance it could account for the dark matter.

The proposed axions have very small mass, no electric charge, and very little interac tion with Standard Model particles.

They would have been produced a lot in the big bang.
Current searches for axions include Earth-based laboratory experiments and searches in the halo of our galaxy and the Sun.
They have never been experimental.

A more precise understanding of the unification of interactions in grand unified 29.5 Dark matter and dark energy 1101 theories can be found in Supersymmetry, an extension of the Standard Model that doubles the number of elementary particles.

The detection of the super partners is one of the main goals of the Large Hadron Col ider.

The lightest superpartner is predicted to be weakly interacting.

The neutralino is the lightest superpartner and is predicted to have a mass of 100 to 1000 times the mass of a protons.
Physicists hope to detect neutralinos by using underground detectors, searching the universe for signs of their interactions, or producing them in particle accelerators.

The mystery of the missing matter of the universe is largely unsolved because none of the particles suggested as a solution have been detected.

Although the dark matter problem has been around since the 1930s, one thing that seemed irrefutable through the 20th century was that the massive objects in the universe would slow the expansion rate of the universe.

In 1998, two independent experiments using the Hubble Space Telescope showed that the universe is expanding more rapidly than in the past.
At the time, no one knew how to explain it.
Saul Perlmutter, Brian P. Schmidt, and Adam G. Riess won the physics prize in 2011.
The extensions of the Big Bang model could explain the expansion.

Physicists came up with a lot of ideas.

Suggest the existence of an energy-fluid that fills space and has a repulsive effect.

There is a new kind of field that creates this acceleration.

Let's look at the ideas.

Einstein included a term for a static universe in general relativity.

There was no evidence for the expansion of the universe at the time general relativity was written.
The general prediction was that the universe was unstable.
Einstein tried to allow general relativity to accommodate a steady state universe by introducing the cos mological constant.

Even though Einstein could have predicted the expansion of the universe, he couldn't accept it.

He considered this his greatest mistake.
The cos mological constant can be used to describe the accelerated expansion because it introduces a repulsive effect into the equation.
An idea that was discarded by Einstein 80 years ago has been resurrected to explain recent observations.

The second idea is a suggestion about what a constant is.

The density doesn't decrease even as the universe expands because it's a property of space.
This energy has a negative pressure.

This causes a repulsive effect on space.

The dark energy density remains constant as the universe expands.

As time passes, the attractive gravitational effect of the matter decreases while the repulsive gravitational effect of the dark energy remains the same.
The repul sion gets stronger as time goes on.
Astronomers have observed that the expansion is more rapid today than it was in the past.

The least radical idea is the third one.

The idea is that there is a better theory of the interaction that would make predictions even better than general relativity.

The new theory has to be constructed in such a way that it doesn't make predictions that are contrary to what has already been done.
Physicists have been unsuccessful in doing this.

Dark energy is the favorite of these three ideas.

The simplest of the vari ous versions represent the dark energy in general relativity as a constant.

Dark energy models have a problem because of a basic feature of quantum mechanics.

The model predicts that the elementary particles in the Standard Model are related to the associated quantum field.

The dark energy is the sum of the zero point energies of the quantum fields.
Physicists get a result that is 10120 times the observed value when they make estimates of what value these models predict.
It has been said that this is the largest disagreement between prediction and experiment in science.

Supersymmetry predicts a doubling of the types of dark matter and dark energy in the universe.

The particles have an associated quantum field.

The total dark energy density is zero.

The dark energy density is not quite zero, because we do observe an accelerated expansion, butOrdinary matter is not consistent with observations.

Supersymmetry is not present in this universe because none of the partner particles have been observed.

The idea of a smal but nonzero dark energy density is consistent with observation.
One of the goals of the Large Hadron Col ider is to produce some of these superpartner particles.

There is a dark matter and dark puzzle.

We know how dark energy affects the expansion of the universe.
Physicists explain patterns in a complete mystery.
Almost all of the total energy was served in nature.
The universe is not dark energy.
23% of the dark matter's rest energy has yet to be detected.
It is possible that one or both of the instruments could add up to 4% of the energy in the universe.

Only a small portion of the universe we live in is understood.

That is a very motivating realization.

4% of the contents of our universe are described in the models we have been building.

The nature of the remaining 98% of our universe is an unresolved problem.

In the late 1800s, the prime minister of England asked Michael Faraday what use he had for his idea.

It was not possible for Faraday to say.
Today, we have electric power generators, microphones, credit card readers, and electric guitar pickups.
They are based on the same thing.

The computing, com munication, and entertainment devices that are present in our everyday lives are a result of J. J. Thomson's understanding of the electron.

Physicists at MIT were studying microwaves in the 1930s.

Microwave radar is believed to have saved England in World War II.
We use microwaves to cook our food and they are involved in satel lite communications.

It's impossible to say for certain, but history suggests that it will.

Maybe it will lead to new sustainable energy sources, the ability to easily travel to other planets, or ways to protect life on Earth.
No one has yet come up with the most amazing future appli cations.

The particles have the same mass but different electric charge.

The photon is one of the particles that are their own antiparticles.
All interactions between objects are related.
Nonfundamental interactions can be understood in terms of these.
Every particle is a quark.

The energy in the universe is thought to be in two different forms.

There are clumps around the galaxies.

Dark energy is thought to be 23%Ordinary matter spread uniformly throughout the universe.

Billions of neutrinos pass through your body every second.

Free neutrons that are not part of a nucleus decay into mentary color protons and other particles with a half-life of about 10 minutes.

There are 0 particles.

An example of a long-range interaction and a short-range Mesons interaction can be given.
There is a difference between the mechanisms.

There are 0 particles.

Three examples of particles are elementary.

Three examples of those that are not physicists are currently known.

Determine the energy in the photon and focus.

The problem can be solved with an isolated electron and positron.

To show the problems, useNewtonian circular motion concepts.

A cloud chamber has a photon entering it.

The photon converts into an elec 3 inside the chamber.

Explain how a picture is taken.

Draw a picture of this situation.

A proton and an antiproton, both with negligible photon, electron, and positron tracks, annihilate each other to produce two photons.

A particle enters a cloud chamber.

There is a useful idea in the page about supersymmetry.

The fundamental interactions should be compared and contrasted.

The interaction is 39.

An electron and a positron are traveling in opposite directions.

There is a difference between a real particle and a virtual spect in the lab where the experiment is being performed.

The electron and positron col ide produce a 14.

Determine the wavelength of the photon.
Explain why you think they will have the same wavelength.

Our Sun converts 19 times a day.

Nuclear fusion creates hydrogen and helium.

The four important steps in the building of the Stan were annihilated with them.

The neutrinos have a very small 26.

Their way to Earth and beyond was unimpeded by the sun's core.

If we can measure the rate at which the sun shines.

There is an independent way to measure the nuclear re 31.

Our bodies have a lot of carbon, oxygen, and ni- higher the intensity of the Sun's radiation.

As hydrogen and helium were produced during the Big bang, these two methods should produce con.

The problem is solved by suggesting that 33.

The neutrinos can't dark matter.

The model predicted the number of neutrinos.

The problem with the solar neutrino was solved.

The nuclear reaction rate wasn't as high as it could have been due to the fact that nearly all the neutrinos are oscillated into other types.

In 1987 a supernova was found.

The reason might be different than thought.

Basic math skills are required for a study of physics at the level of this textbook.

The math topics are summarized in this appendix.

If you review this material and become comfortable with it as quickly as possible, you can focus on the physics concepts and procedures that are being introduced, without being distracted by unfamiliarity with the math that is being used.

In physics, exponents are used a lot.

It is said that 3 will be raised to the fourth power.
The number 34 is equal to 3, 3 and 3.
There are special names for operations when the exponent is 2 or 3.

Any quantity raised to the zero power is considered to be unity.

26 can also be written as 61/2.

To verify the result, look at the numbers 32, 33, and 1921272.

If you want to verify this result, you need to know that 24 is 16 and 34 is 81.

To verify this result, you need to know that 22 is 4, so 12223 is 1423

The exponents are being manipulated.

The validity of the equation is not affected by raising each side of the equation to the 1 sides.

When expressing a quantity, it is important to use the proper number of significant figures.

If the power of 10 is positive, it means the number of places the decimal point is moved to the right to get the fully written-out number.

If the power of 10 is negative, the number of places the decimal point is moved to the left to get the fully written-out number, is 10.

10 is the correct power of 10 to use when the number is written in scientific notation because the decimal point is moved three places to the left.
The keys for expressing a number in either decimal or scientific notation can be found in most calculators.

When two numbers are written in a scientific way, the power of 10 is used to get the decimal part of the re sult, and the power of 10 is used to divide the result.

The location of the decimal point may have to be adjusted in the answer.

2.0 is the number of 10-3-1-62.

Your calculator can handle these operations for you, but it is important for you to have a good sense of number sense.

In physics, equations written in terms of symbols represent quantities.

The combination of quantities on the left of the equals sign has the same value as the combination on the right of the equals sign.

Adding or subtracting a number or symbol is one of the operations that could be done.

We subtract 4 from both sides.

To get tual y two, we divide both sides by 2.

One may represent the answer if we raise both sides of the equation to the 1 ics problem.

3 does satisfy the equation.

24 is 2.

The equation has two solu tions.

A quadratic equation has two roots.

The two roots are the same.
The original equation has mathematical solutions, but no physical solutions.

The true physical answer is represented by either the one or the other.

Our previous result is 14 which agrees with it.

A pair of equations in which all quantities are symbols can be combined to eliminate unknowns.

The final step of a physics problem is often best solved with symbols.

You need to raise 10 to the power 3 to get 1000. cal culators have a key for calculating the log of a number

Sometimes we are given a log of a number and asked to find the num ber.

If the number is greater than 1, the log of the number is positive.

If the number is less than 1, the number is negative.
The log of zero or a negative number is not defined.

It's important to note that ln 1 is equal to 0.

Two straight lines intersect and form interior angles.

The alternate interior angles are equal when two parallel lines intersect by a diagonal straight line.

The two angles are equal when the sides of one angle are parallel to the other.

One side of a straight line has 180 angles.

The angles in a triangle are 180.

Similar triangles have the same angles and ratios.

One can be placed on top of the other if the triangles are congruent.

The square of the hypotenuse is the sum of the squares of the other two sides.

If two right triangles have the same value for one acute angle, then the other two triangles have the same ratio of corresponding sides.

The functions are written sin, cos, and tan.

The angles are expressed in degrees or radians.

A key is needed to switch between degrees and radians.

A right triangle has one angle of 30 and one side with a length of 90.

The previous result was 16.0 cm.

The Pythagorean Theorem was used in combination with a trig function.

The trig functions are ratios of lengths.

Each function of the right triangle is positive and negative.

The Pythagorean theorem and cos are out of step.

The other has its maximum magnitude when one is zero.

Trig identities are some of the relations among trig functions.

A displacement is represented by a vector.

The arrows graphically represent the quantities.

The direction is 25 North of East and the distance is 200 m.

You take a two-day trip.

The second day may involve another 500 km displacement, but not necessarily in the same direction.

The net displacement is northeast of your starting position.

The net result is what we are concerned with when adding displacement 500-km successive trips.

The following graphical technique can be used to add two vectors.

Adding images graphically.

The order in which another technique was introduced.

If you add the care using a ruler and protractor, it's the same method as if you did it from the tail.

60 south of east is where we measure the magnitude of the resulting angle.

Determine the net displacement with a ruler and find out its length.

The magnitude of the result is equal to the difference in the magnitudes of the vectors being added.

The magnitudes of parallel vectors can be added.

The method of adding and subtracting is graphical.

To subtract tors.

The force that other objects exert on an object of interest is represented by the force in the vectors.

Let us see how the components work.

The axis is shown in Figure B.14d.

We can use our knowledge of ge ometry to find the length of the result.

The numbers here have two significant digits.

-39 is equal to 0.802

This operation can now be summarized.

The three forces are shown in Figure B.13.

The number is 21-37 N22 and the number is 152 N22.

The results of the component calculation can be used.

+ 24 N + 1-35 N2 + 1-26 N2 equals 1.41.

You can use a positive or negative number.

To change the magnitude of a negative number, reverse it.

In Figure B.15b, we add up the number by 1-12 and by 1-22.

The seven base units listed below are used to build the SI system of units.

The base units are combinations of two or more derived units.

The International Bureau of Weights and Measures stored the mass of an international standard in a vault in France.

The amount of radiation that was emitted by a particular transition of a cesium-133 atom.

The force on each other is caused by the constant electric current that flows in two very long parallel straight wires placed 1 m apart in a vacuum.

There are as many carbon atoms in a substance as there are elementary entities.

The particles could be specified groups or atoms.

The intensity of the light source's radiation and the intensity of the light source's radiation and the intensity of the light source's radiation and the intensity of the light source's radiation and the intensity of the light source's radiation and the intensity of the light source's

It's true because an observer can see an object moving when all interactions are balanced.

For and observer B can see the same thing.
When a passenger on a bus observes her purse slide off her are sitting on a train without any extra objects pushing the train but are moving with respect to the trees on the ground, you are not moving with respect to the lap.

We can determine if the object is moving at a constant rate.

The path length is 16 km.

The product of the object's mass is equal to the area of a rectangle.

The scale reads the force that it exerts on the displacement.

The sum of the forces is not read by it.

If it did, you can see a car in the parking lot that should be zero when the elevator is not in use.

The rollerblader pushes the floor, and the floor pushes the tion in the opposite direction.

Extending the stopping distance will allow you to either up or down at your convenience.

During the stopping process, the acceleration can be reduced.

If the tailgating car sees the first car's brake lights, the component is positive.

After the reac positive direction on the axis and the negative direction on the axis, the tailgating car's speed starts to decrease.

P--person, S-- surface, E--Earth until they collide.

It is possible that the E on C interaction with the air is weak.

The axis is a pair of motion diagrams.

The sum to the surface was shown in our analysis.
If the forces on the object were zero, it would be difficult to solve the problem because the object moved at different speeds.

The sum of the force is zero, the horizontal motion and the magnitudes and opposite directions are analyzed.

The elevator should move at a constant rate.

Observers look for an object in reference frames.

The engine can't exert a zero because it's a part of the system.

An external force will accelerate the car system.

The circle is connected to the velocity vector.

The mass of the ve is huge.

The block and the bullet were considered a system.

The bullet's acceleration force is an internal force.

The skateboard was rolling in the negative direction at ward the center of the circle.

The upward normal force of the ball and the mass of the system are important in determining the system's momentum.

There is no net mass of the meteorite because the mass of Earth is huge compared to the surface.
Take the meteorite and Earth to force in the opposite direction.
The system should be in the horizontal plane.
When the meteorite hits Earth, they both con the table while the ball is in contact with the semicircular ring, so that the ring exerts an inward force on the ball toward the center.
The force causes the ball to accelerate before and after the collision, but it doesn't cause the system center of the circle to move.
The mass of Earth makes it tiny.

The ball will move in a certain direction after it leaves the barrier.

The dimensions are correct because Earth exerts its force on the Moon in a way that is close to the Moon's.

The woman's speed is related to the drum.

As the sys surface intercepts her forward path and pushes in on her, the drum's by some external object on the object in the system.
The system doesn't have work.
She was moving in a circular path.
The state of a system can be characterized by the drum preventing her from falling.

We can either do it in one of two ways.

It seems like a force to Earth is changing.
As the mass exerts on the object, it changes elevation.
The mass of one of the objects is 1026 kilograms, which makes it easier to use in problem solving.

The force that you would exert on the spring while stretching between the center of Earth and any object is not constant in magnitude.

From 0 to 6000 km it increases linearly.

The word "fall" implies the motion of an object when only the force of Earth exerts it.

This method doesn't account for flies forward all the time.
The thermal energy change of the touching surface of objects is combined with the Moon's ability to fly forward and fall toward Earth.

It lands on its circular path system and accounts for the energy change as an internal energy around Earth.

Earth's work is involved in burning.

The quantity is called momentum.

Their momenta was zero.

If the numbers are the same, no energy went into collision because both carts had zero speeds.

When an ice skater is rotating faster and faster in a clockwise way, there is no work done on Jim, she has no energy changes, and her rotation is negative.

The ro we choose when she slows down.
The power is zero.

The potential energy of two objects can be negative.

When we put the same magnitude force on the zero energy reference separation to be very far apart for the exam cylinder, it was the same as when we put the same magnitude force on the zero energy reference separation to be infinitely far apart.

If the force determines the potential energy of two objects that attract the same speed of rotation, the outcomes of both of them.
Positive work is required to pull them apart, but this is not what we found.

The negative energy started when the force was farther from the axis.

We concluded from the experiments that it was the Torque that affected the acceleration.

The wooden ball will change in motion with the same Torque.

There is a cause-effect relationship between the laws.

The force that Earth exerts on the painting will not cause an object to interact with another object.

When we support an object at the center of mass, it is the object's properties.

A person is jumping on a merry-go-round.

Her landing increases the rigidity of the system and decreases the speed at which it moves.

A person is jumping off a carousel.

The person was the sum of both points on the axis of rotation.
When the ob person steps off and the ject is in equilibrium, the rotation of the carousel remains the same.

The can is similar to the bottle.

One way to do it is to put the person face down on a big ex bottle filled with ice, which rotates as it rolls down.

Roll the ball under him until he can balance on it.

The center of mass is where the ball will be.

The external force on the backpack is caused by the Torque exerted by the muscle against the bing.

Earth's rotation is slowed by the straps of the backpack.

The trapezius exerts force at an angle to diminish its effect.

When liquid particles are moving randomly, the muscle exerts force to balance the object's surface.

The distances themselves do not tell us much.

To answer this question, consider the forces that were put on to compare them to the size of the particles.
As the size of the ball and the pencil when in equilibrium is about 10-8 cm, the average distance between particles is about 10-7 cm and when the equilibrium is disturbed it is about 30 times larger.

When hitting the wall, the force of the gravity exerts a greater force on the pencil.

The force of a collision moves the pencil farther away from its equilibrium.
If the particles move back and forth.

The muscles exert force on the bone at different distances.

The equation seems reasonable.

The work-energy equation is what they are based on.

The Bernoulli charts to fluid processes and the work-energy charts to solid objects are related to how quantities are not measured directly.

The cause of the fluid energy density to change was tested by the experiment.

They apply to the theory as well.
The goal of the experiment was to see if the particle speeds matched the predictions based on the initial and final sit ideal gas model.

The air pressure at both levels is open.

The time when the Sun emits atmosphere was calculated.

Your blood pressure can be 4.5 billion years old.

As your heart needs less work in pumping blood, the Sun must have some other be lower.

You may have fewer heartbeats.

The air pressure is reduced because the air's energy density is greater.

In this case, Earth, the magni scale is used to determine the mass of the object.

The object should be submerged in the water in a graduated cylinder to see the change in the water level.
The volume should be equal.
In skydiving, the net force is zero and the water is displaced to determine the volume of the object.
To find density, divide mass by volume.

You exert a diver when you squeeze the closed end of the tube.

The sum of additional pressure that is transferred uniformly in all directions is taken into account.

Liquid layers of the magnitude of Earth's gravity support the liquid above it at different heights.

The pressure is the same in all directions at the same height.

As the depth of the fluid increases, the work-energy equation allows us to find the final en tainer.

The upward pressure of the fluid on the system is caused by an ob ergy of a system from knowing its initial energy and the work ject submerged in a fluid.
The bottom surface of the object is more important than the bottom of the object in determining fluid pressure on the top of the object.

When a block of iron or aluminum is added to cool the object.

The force is determined by the volume of the mass, the water and block reach the same final fluid.

If the ship's perature changes less, you can measure how much water it displaces.

Imagine that the same amount of energy is used to submerge.

The change in the tempera air in between them is lower than the pressure outside, which is why the lightbulbs came together.

The ture is less.

The area of the river before the outlet is supplied with a unit mass of a substance to change its temperature more than the area of the cross section at the outlet.

Water flows at higher speed through the outlet with the smaller supplied at constant temperatures to a unit mass of a substance cross-sectional area.

Most of the time, we prefer streamlined flow.

There is less heat in fusion.

The heart doesn't have to work as hard because Conduction is efficient in transferring energy from atom to atom.

If the warm parts of the system had no electric potential energy, then we would transfer energy through liquids and gases.

The best way to transfer energy through a vacuum is if the nucleus of the particle is positive.
The final result wouldn't change.

Carbon dioxide does not absorb all of the visible light and short-wavelength radiation.

At the point of interest, this reduces the cooling rate of Earth.

Adding them as a sphere contributes to the increase of Earth's temperature.

The point of interest is not related to the chemical potential in their bonds.

Even though a relatively small part is converted tential from A to B and from C to D, the work is the same and equals the change in electric po less organized.

The can Energy was increased but the entropy was increased.

If there is a nonzero electric field inside, the field exerts the change in entropy.

The second law was formulated for isolated systems.

The re net field is zero.

The net electric field is zero inside a conducting material placed in an external electric dynamics expression that depends on the difference in tempera field.

The field is not completely zero.
There are other factors that limit the efficiency.
In the conductors there are moving parts and burning of electrons that can cancel the external field.
The fuel is used for the hot reservoir.

The plates are in the same direction between charged objects.

The rod needs to be grounded.

The negatively charged particles can be tively charged so that their net electric done by running a wire on the outside of the house is zero.
Some electrons leave the rod to the ground.

There is a ratio.

There has to be a continuous path for the particles to travel.

If the charges are the same, both positive and nega side the battery, and from low to high inside the battery.

The energy can only be reduced by increasing the distance between the negatively charged electrons.
If the charges are not the same, the energy can only be used outside the battery and can be reduced by moving them closer together.

You can determine the magnetic force inary positive charge moving from the positive terminal of the on 2 by tracing the path of an imag distance of 1.0 m.

The experiment is the same as before.

The electric charge is a conserved quantity.
There is no place for the charge to come from or leave the path.

The bulbs that are on do or on a current-carrying wire, when you turn on extra appliances.

The 60-W bulb has a higher resistance than the 100W wire.

The 60-W bulb should point down in the series.

The potential is higher on the side where the current enters condition causing a constant electric field and a constant potential than on the side where it leaves.

An external magnetic field causes atoms in diamagnetic, which is almost no difference across a conducting wire, as its materials become slightly magnetized opposite the magnetic resistance.

The direction of the current is opposite to the field.

There are differences in direction that we chose as positive.

When a bar magnet moves with respect to a coil, the magnetic the models of resistivity explains its increase with temperature field through the coil changes--thus a current should be initiated.

The crystal lattice needs to be vibrated violently.

To get the same electric current through the system, you need a switch and a galvanometer.

The galvanometer will detect a higher emf if you close the switch in the first coil.

The north pole of the compass needle is attracted to both the north pole of the magnet and the other pole as they move towards the opening of the positively and negatively charged objects.

Poles must not be negatively or positively charged because of the increase in the magnetic field through the coil.

The result and wire length are not related.

A runaway current would cause the coil to melt.

The area and orientation are both factors in the rate netic field.

In the case of Observational Experiment Table 18.3 we erted on the wire because it was determined by the sources that wanted to focus on the change in the magnetic field.

The magnetic force is always in the same direction.

Current-carrying wire 1 is the source of the coil.

A changing magnetic field through the brain is caused by a changing current in the coil on the scalp.

The changing magnetic field in the brain causes circular elec ergy change.

The pendulum length is smaller than the effective speed, so it has to move at a larger speed.

The springs that obey Hooke's law exert a force on an ob that is larger than the example.

The resistance with the stretch or compression of the spring and points decreased as the length of the wire decreased.

The angle between the normal line and the coil rotates.

The restoring force is needed for the coil and the direction of the magnetic field to change.

The emf is triggered if a system undergoes damped motion.

The magnetic field produced by electric current in the core confines the magnetic field produced by an external source.

The external interaction with the system causes a larger or smaller alternating emf across the secondary coil, a force that always does positive work, thus increasing the total depending on the relative number of loops in each coil.

Magnetic force is exerted on the electric charges in the moving Earth as the CO2 absorbs some of the IR radiation and sends it back to the Earth.

The force causes a charge separation similar to the pro reducing the energy leaving Earth.

The electric field created by unbalanced charges exerts forces on other charges in the wire.

The end of the Slinky should be vibrated to move around the loop in a coordinated fashion.
There is no power source in the loop for the wave.

The book goes through the same places.

This speed does not depend on the speed of wave propaga, but on the frequencies and amplitude of rections during one cycle of motion.
There isn't a specific location along the tion.
As long as he is pushing the travels through the medium, the wave's speed can be determined.
The book is never in the equilibrium position.
There is no sound of the wave.

The quantities are related by definition, not by thickness.

The A string has a cause-effect relationship.
Period and Frequency are pulled tighter than the G string.

On other features of the vibrating system not yet discussed, the intensity of the wave decreases.

The re brations of a Slinky are about 1.5 seconds.

The object starts vibrating.

The spring constant on the end of a Slinky cart is 0.057 kilograms.

Your friend can create an oppositely oriented pulse from the 0.2 m amplitude.

As they pass in the middle, the pulse would cancel.

The period will decrease by a factor.

Every 2.0 s the cart passes, the cart's 2.0-s period means.

It depends on the sensitivity of the same position moving in the same direction.
The cart has a maximum positive displacement ness of sound that depends on both the frequencies and the amplitude.

The position at which it is at has a maximum potential energy.

The cart passes the equilibrium position and has more than one wave.
Potential energy is zero, so we can look at the sound.

Small erratic motion is the maximum elastic potential energy.

Standing waves are not produced by all frequencies of vibration.

An object emits light in all directions and is represented by a speed of the air inside the pipe.

We can easily predict the path of the ambulance.

To double the focal ing distance between you and the ambulance, you need to place it at a distance equal to that.

The object will be the same size as the image.

When the ambulance is moving away from you, the ray diagram helps predict where the image will be.

The waves get stretched in a longer space with your calculation.

The focal length of the system lens-cornea can change in the camera and in the eye.

He can look at the images because his point is farther away.

The image will be bigger if there is one ray from each point.

A telescope magnifies the size of an object but it doesn't magnification the object itself.

According to the wave model of light, light leaving each laser beam should be reflected after bouncing off these mirrors narrow slit moves outward in all directions; each slit is a source using the law of reflection and perform the actual experiment to of circular wavelets.

The wavelets from the slit see if the prediction is close to the outcome.

Bright light can be seen at many places when a border is different from a ray of light.

According to the law of reflection, light in glass is 1/6th the speed of air.

When it travels through media second medium, the fre and some of it bends and travels in a different direction.

The phenomenon of total internal reflection occurs when light travels from a denser medium to a less dense one.

The locations of the maxima are the same.

The colors produced by a grating and a film are due to the reflection of light going from water to glass.

The sky is blue because the chemical composition of the grating causes it to reflect blue light in all directions.

The colors of thin clouds are white because their tiny water droplets reflect all col films in the same way, but bands of white light with one ors in the same way.

The image of a star is not what we see on the film.

It is a pattern of light reflected from the telescope's opening.

You will see the same amount.

The mirror is near a wall facing the window.

Take a small piece of cardboard and place it in front of units for the length-related quantities in the same equation.

When you see a sharp image of the window, slowly move the cardboard away from the mirror.

There are different types of images that can be produced by cave mirrors.

The strategies should be used together.

Review Question 22.2 describes how to produce an electromagnetic wave.

Light can travel without a medium, and the speed of light charged particles vibrate back and forth in a coordinated way.

They both measure the time interval for a wave to travel from one object to another.

Observers can hear a different sound in different frames.

The Sun exerts a force on the Earth.

The Sun curves space, and more satellites to the target, while the EM waves travel from three or general relativity terms.
Earth naturally moves along a curved path after the travel times of those signals.

The motion of the satellites affects the location of the object.

Waves in a vacuum are the same.

The second wave will have half the wavelength of the first wave.

The surface area of a sphere is four times bigger than the energy spread over it.

The surface area of a sphere is proportional to the amount of energy it has.
Classical physics says a charged particle can emit its radius.

The independence of the stopping potential on the inten tric field is in the plane parallel to the horizontal plane sity of light.

The metal has a minimal energy that is reduced by the reflected light.

At low light intensity, Vavilov and Brumberg saw individ cists set out expecting a particular result based on their under ual flashes of light on the screen.

Invariance is a principle ofNewtonian physics that states that the laws of physics are the same in all places, even if light waves interfere with pro reference frames.

The same equations should be used in all minima.

The electrons traveling across the tube stop in front of the reference frame.

It is possible that the events seen as happening are not happening when they accelerate.

Since the acceleration was so large, they ran at the same time.

The photon's momentum is proportional to the person's lifetimes.

If one assumed that for initially stationary electron, the muon lifetime increased, then the photon must lose its momentum.
The wave is the time dilation equation.

The materials should have a small function so that they can move with you.

No one will be able to see the cutoff frequencies.

The electron is charged.

The circle has the relativistic velocity moving in it.
Due to the limitations of the second emission, the energy of the atom would decrease and the size of the atom would decrease as well.
Formation does not occur when the atom loses its structure.

The zero point reference level of the electron-nucleus elec is when they are far apart.

The momentum of an isolated system is not constant.

The classical equation energy is reasonable for two particles bound together.

The mass of the product is less than the mass of the object.

A small fraction of the reactant mass is converted into an instrument that allows you to see light and other forms of energy.
If we include the ferent colors in different locations, and a container holding the rest mass energy of the particles involved in the process, we can conserve energy.

The strontiums traveled in during the reaction.

The number of remaining forms do not have a constant phase difference after 200 years.

200 years earlier, the number of radioactive nuclei that stimulated emission travel in the same direction and were present in the same location as the strontium strontium strontium strontium strontium strontium strontium strontium

The carbon in the body stays constant as we inhale it.

The older the specimen, the higher the ratio.

There are peaks and troughs in the number of electrons.

A free protons has too little energy to decay into a troughs because it is less mass than the atoms in a lattice.

The attractive strong interaction between pro ference of electrons passing through two slits and the nonzero tons is greater than the repulsive electric interaction between width of the lines.

The major difference is that the electron has a field that is 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- 888-609- The particles with no electric charge are made of quarks.

The charged particles travel in a direction consistent with the protons and the electron is a lepton.
The electron is negatively charged and the direction of the magnetic field on the protons is positively charged.
The charged particle has a mass.

As the universe expanded, the average temperature eventu tude of the potential energy of the nucleus-electron system became cool enough to match the magnitude of the electron's energy.

For neutral atoms to form.
An electron total energy of the system is positive.

An electron in a nucleus would escape quickly.

The photon were produced at the nucleus.
Electrons are not components of the nucleus.

The energy needed to remove a microwave background is ionized.

By applying the laws of motion and gravitation to ergy, we can estimate how much energy is needed to separate the nucleus from the stars.

The latter is much bigger.

The runners' distance will increase.

24.7 m>s2 85

10 N will accelerate.

The force diagrams are the same in 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 is 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 is 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110 888-739-5110

The force diagrams are the same.

10-3 m>s2 23

2.43 m>s2 55

2.70 m>s 25

It's 37.6% of what it is on Earth.

Projectile fired at u2 is more resistant to air resistance.

6.13 m>s2

The object of reference is Earth.

1 - 10 m>s 33.

540 J 43.8 m>s 41

Lifting 196 J, carrying 0, setting down -196 J, total 0 1.33 m>s 47.

330 N>m 25 is the number.

Right 617 N and left 250 N 27.

1100 N, 1100 N (c), 1100 N, 1100 N, 1100 N, 1100 N, 1100 N, 1100 N, 1100 N, 1100 N, 1100 N, 1100 N, 1100 N, 1100 N, 1100 N, 1100 N, 1100 N, 1100 N, 1100 N

H on B is 54.1 N.

The atmospheric pressure is 39.

106 N>m2 57

The oil's density is 900 kilogrammes.

2300 kilo 3.

Both are incorrect; 6 * 103 N 5.

105 N>m2 35 104 N>m2 39.

Liquid B has more density than liquid A.

The water side will tilt up.

The person will sink.

The pressure will not change.

There are 19 cms.

It is likely to be iron.

There are 10-4 kgs.

They will be attracted with force.

The spheres are not the same.

Further away from sphere A is the pipe side.

A B C D E F G H I J A 31.

The force will be increased.

The needle should point downward.

The transformer has a turn ratio of 13.33:1.

A along the line with Source A and B 43.

The mirror is above the horizontal.

10 cm is 60, 33, 27 and 47.

5.8 increase and 59 decrease.

-12 cm, -2.7 cm 67.

31mm is the diameter of the bead.

The Earth is 2 * 1017 W 9.

710 W>m2, 94 W>m2 45.

105 W>m2 53.

W>m2 is 57.

118 m>s 1.

There were 295,791,858 m>s.

Problems were being accelerated.

Elementary particles are classified according to their fundamental 45 eV interactions.

The other particles have mass.

During the 60 eV period when neutral atoms first formed, the Cosmic Background Radiation was produced.

There were 106 m>s 63.

71: opener: Bruce Mitchell/Getty; Figure 12.1; Figure 12: Cheryl Power/ Photo Researchers, Inc.; Figure 2.8: fStop/Alamy.

Figure 13.1: PhotoStockFundamental-Israel/Alamy; Figure 3.17: HP Canada/Alamy; Figure 13.5: misu/

Wrangel/Shutterstock; Figure 6.10: Ted Foxx/Alamy; Figure P6.23: EPA/Horacio Villalobos/ Newscom.

The opener is Matt Tilghman/Shutterstock.

Figure 8.19: Associated Press/Aman Sharma; Figure 8.21: JP5/ZOB/WENN/ Newscom.

Figure 19.09: NASA; Figure 19.13: Alamy; Figure 19.15: imagebroker.

Figure opener: Michael Ventura/Alamy, Figure 29.1a: Lawrence Berkeley, and Figure 29.2c: Lawrence Berkeley National Photo Researchers, Inc.

There are constant pressure processes.

There are coin sorters in vending machines.

Mega-newtons exert themselves by wires on large halo objects.

Weakly interacting large particles.

The first step in physics problem solving is to read the text of the problem and come up with a numerical answer.

It is difficult to translate the words and equations into each other.

One way to address this is to represent physical processes in ways that are less abstract.
Concrete representations help you visualize a problem.
The representations are used to bridge the words and equations.
The multiple representation approach to problem solving is an approach that you will learn to use as you progress through the book.

The car's speed goes down.

A person is falling.

A human cannonball is launched.

Document Outline

Cover

Title Page

About the Authors

Acknowledgments

Contents

I. Introducing Physics I.1 What is physics? I.2 Modeling I.3 Physical quantities I.4 Making rough estimates I.5 Vector and scalar physical quantities I.6 How to use this book to learn physics Summary

1 Kinematics: Motion in One Dimension 1.1 What is motion? 1.2 A conceptual description of motion 1.3 Quantities for describing motion 1.4 Representing motion with data tables and graphs 1.5 Constant velocity linear motion 1.6 Motion at constant acceleration 1.7 Skills for analyzing situations involving motion 1.8 Free fall 1.9 Tailgating: Putting it all together Summary Questions Problems

2 Newtonian Mechanics 2.1 Describing and representing interactions 2.2 Adding and measuring forces 2.3 Conceptual relationship between force and motion 2.4 Reasoning without mathematical equations 2.5 Inertial reference frames and Newton's first law 2.6 Newton's second law 2.7 Gravitational force law 2.8 Skills for applying Newton's second law for one-dimensional processes 2.9 Forces come in pairs: Newton's third law 2.10 Seat belts and air bags: Putting all together Summary Questions Problems

3 Applying Newton's Laws 3.1 Force components 3.2 Newton's second law in component form 3.3 Problem-solving strategies for analyzing dynamics processes 3.4 Friction 3.5 Projectile motion 3.6 Using Newton's laws to explain everyday motion: Putting it all together Summary Questions Problems

4 Circular Motion 4.1 The qualitative velocity change method for circular motion 4.2 Qualitative dynamics of circular motion 4.3 Radial acceleration and period 4.4 Skills for analyzing processes involving circular motion 4.5 The law of universal gravitation 4.6 Satellites and astronauts: Putting it all together Summary Questions Problems

5 Impulse and Linear Momentum 5.1 Mass accounting 5.2 Linear momentum 5.3 Impulse and momentum 5.4 The generalized impulse-momentum principle 5.5 Skills for analyzing problems using the impulse-momentum equation 5.6 Jet propulsion 5.7 Meteorites, radioactive decay, and two-dimensional collisions: Putting it all together Summary Questions Problems

6 Work and Energy 6.1 Work and energy 6.2 Energy is a conserved quantity 6.3 Quantifying gravitational potential and kinetic energies 6.4 Quantifying elastic potential energy 6.5 Friction and energy conversion 6.6 Skills for analyzing processes using the work-energy principle 6.7 Collisions: Putting it all together 6.8 Power 6.9 Improving our model of gravitational potential energy Summary Questions Problems

7 Extended Bodies at Rest 7.1 Extended and rigid bodies 7.2 Torque: A new physical quantity 7.3 Conditions of equilibrium 7.4 Center of mass 7.5 Skills for analyzing situations using equilibrium conditions 7.6 Stability of equilibrium 7.7 Static equilibrium: Putting it all together Summary Questions Problems

8 Rotational Motion 8.1 Rotational kinematics 8.2 Torque and rotational acceleration 8.3 Rotational inertia 8.4 Newton's second law for rotational motion 8.5 Rotational momentum 8.6 Rotational kinetic energy 8.7 Rotational motion: Putting it all together Summary Questions Problems

9 Gases 9.1 Structure of matter 9.2 Pressure, density, and the mass of particles 9.3 Quantitative analysis of ideal gas 9.4 Temperature 9.5 Testing the ideal gas law 9.6 Speed distribution of particles 9.7 Skills for analyzing processes using the ideal gas law 9.8 Thermal energy, the sun, and diffusion: Putting it all together Summary Questions Problems

10 Static Fluids 10.1 Density 10.2 Pressure exerted by a fluid 10.3 Pressure variation with depth 10.4 Measuring atmospheric pressure 10.5 Buoyant force 10.6 Skills for analyzing static fluid processes 10.7 Buoyancy: Putting it all together Summary Questions Problems

11 Fluids in Motion 11.1 Fluids moving across surfaces--Qualitative analysis 11.2 Flow rate and fluid speed 11.3 Causes and types of fluid flow 11.4 Bernoulli's equation 11.5 Skills for analyzing processes using Bernoulli's equation 11.6 Viscous fluid flow 11.7 Applying fluid dynamics: Putting it all together 11.8 Drag force Summary Questions Problems

12 First Law of Thermodynamics 12.1 Internal energy and work in gas processes 12.2 Two ways to change the energy of a system 12.3 First law of thermodynamics 12.4 Specific heat 12.5 Applying the first law of thermodynamics to gas processes 12.6 Changing state 12.7 Heating mechanisms 12.8 Climate change and controlling body temperature: Putting it all together Summary Questions Problems

13 Second Law of Thermodynamics 13.1 Irreversible processes 13.2 Statistical approach to irreversible processes 13.3 Connecting the statistical and macroscopic approaches to irreversible processes 13.4 Thermodynamic engines and pumps 13.5 Automobile efficiency and power plants: Putting it all together Summary Questions Problems

14 Electric Charge, Force, and Energy 14.1 Electrostatic interactions 14.2 Explanations for electrostatic interactions 14.3 Conductors and nonconductors (dielectrics) 14.4 Coulomb's force law 14.5 Electric potential energy 14.6 Skills for analyzing processes involving electric force and electric potential energy 14.7 Charge separation and photocopying: Putting it all together Summary Questions Problems

15 The Electric Field 15.1 A model of the mechanism for electrostatic interactions 15.2 Skills for determining E fields and analyzing processes with E fields 15.3 The V field 15.4 Relating the E field and the V field 15.5 Conductors in electric fields 15.6 Dielectric materials in an electric field 15.7 Capacitors 15.8 Electrocardiography and lightning: Putting it all together Summary Questions Problems

16 DC Circuits 16.1 Electric current 16.2 Batteries and emf 16.3 Making and representing simple circuits 16.4 Ohm's law 16.5 Qualitative analysis of circuits 16.6 Joule's law 16.7 Kirchhoff's rules 16.8 Series and parallel resistors 16.9 Skills for solving circuit problems 16.10 Properties of resistors 16.11 Human circulatory system and circuit breakers: Putting it all together Summary Questions Problems

17 Magnetism 17.1 The magnetic interaction 17.2 Magnetic field 17.3 Magnetic force exerted by the magnetic field on a current-carrying wire 17.4 Magnetic force exerted on a single moving charged particle 17.5 Magnetic fields produced by electric currents 17.6 Skills for analyzing magnetic processes 17.7 Flow speed, electric generator, and mass spectrometer: Putting it all together 17.8 Magnetic properties of materials Summary Questions Problems

18 Electromagnetic Induction 18.1 Inducing an electric current 18.2 Magnetic flux 18.3 Direction of the induced current 18.4 Faraday's law of electromagnetic induction 18.5 Skills for analyzing processes involving electromagnetic induction 18.6 Changing B field magnitude and induced emf 18.7 Changing area and induced emf 18.8 Changing orientation and induced emf 18.9 Transformers: Putting it all together 18.10 Mechanisms explaining electromagnetic induction Summary Questions Problems

19 Vibrational Motion 19.1 Observations of vibrational motion 19.2 Period and frequency 19.3 Kinematics of vibrational motion 19.4 The dynamics of simple harmonic motion 19.5 Energy of vibrational systems 19.6 The simple pendulum 19.7 Skills for analyzing processes involving vibrational motion 19.8 Including friction in vibrational motion 19.9 Vibrational motion with an external driving force 19.10 Vibrational motion in everyday life: Putting it all together Summary Questions Problems

20 Mechanical Waves 20.1 Observations: Pulses and wave motion 20.2 Mathematical descriptions of a wave 20.3 Dynamics of wave motion: speed and the medium 20.4 Energy, power, and intensity of waves 20.5 Reflection and impedance 20.6 Superposition principle and skills for analyzing wave processes 20.7 Sound 20.8 Pitch, frequency, and complex sounds 20.9 Standing waves on strings 20.10 Standing waves in air columns 20.11 The Doppler effect: Putting it all together Summary Questions Problems

21 Reflection and Refraction 21.1 Light sources, light propagation, and shadows 21.2 Reflection of light 21.3 Refraction of light 21.4 Total internal reflection 21.5 Skills for analyzing reflective and refractive processes 21.6 Fiber optics, prisms, mirages, and the color of the sky: Putting it all together 21.7 Explanation of light phenomena: two models of light Summary Questions Problems

22 Mirrors and Lenses 22.1 Plane mirrors 22.2 Qualitative analysis of curved mirrors 22.3 The mirror equation 22.4 Qualitative analysis of lenses 22.5 Thin lens equation and quantitative analysis of lenses 22.6 Skills for analyzing processes involving mirrors and lenses 22.7 Single-lens optical systems: Putting it all together 22.8 Angular magnification and magnifying glasses 22.9 Telescopes and microscopes Summary Questions Problems

23 Wave Optics 23.1 Young's double-slit experiment 23.2 Index of refraction, light speed, and wave coherence 23.3 Gratings: An application of interference 23.4 Thin-film interference 23.5 Diffraction of light 23.6 Resolving power: Putting it all together 23.7 Skills for analyzing processes using the wave model of light Summary Questions Problems

24 Electromagnetic Waves 24.1 Polarization of waves 24.2 Discovery of electromagnetic waves 24.3 Some applications of electromagnetic waves 24.4 Frequency, wavelength, speed, and the electromagnetic spectrum 24.5 Mathematical description of eM waves and eM wave energy 24.6 Polarization and light reflection: Putting it all together Summary Questions Problems

25 Special Relativity 25.1 Ether or no ether? 25.2 Postulates of special relativity 25.3 Simultaneity 25.4 Time dilation 25.5 Length contraction 25.6 Velocity transformations 25.7 Relativistic momentum 25.8 Relativistic energy 25.9 Doppler effect for eM waves 25.10 General relativity 25.11 Global Positioning system (GPS): Putting it all together Summary Questions Problems

26 Quantum Optics 26.1 Black body radiation 26.2 Photoelectric effect 26.3 Quantum model explanation of the photoelectric effect 26.4 Photons 26.5 X-rays 26.6 The compton effect and X-ray interference 26.7 Photocells and solar cells: Putting it all together Summary Questions Problems

27 Atomic Physics 27.1 Early atomic models 27.2 Bohr's model of the atom: Quantized orbits 27.3 Spectral analysis 27.4 Lasers 27.5 Quantum numbers and Pauli's exclusion principle 27.6 Particles are not just particles 27.7 Multi-electron atoms and the periodic table 27.8 The uncertainty principle Summary Questions Problems

28 Nuclear Physics 28.1 Radioactivity and an early nuclear model 28.2 A new particle and a new nuclear model 28.3 Nuclear force and binding energy 28.4 Nuclear reactions 28.5 Nuclear sources of energy 28.6 Mechanisms of radioactive decay 28.7 Half-life, decay rate, and exponential decay 28.8 Radioactive dating 28.9 Ionizing radiation and its measurement Summary Questions Problems

29 Particle Physics 29.1 Antiparticles 29.2 Fundamental interactions 29.3 Elementary particles and the standard Model 29.4 Cosmology 29.5 Dark matter and dark energy 29.6 Is our pursuit of knowledge worthwhile? Summary Questions Problems

Appendices A: Mathematics Review B: Working with Vectors C: Base Units of sI system D: Atomic and Nuclear Data E: Answers to Review Questions F: Answers to select odd-Numbered Problems

Credits

Index A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Home

29.1 Antiparticles

After the emission of a positron, each positron interacts with a nearby electron, causing a pair of photons to travel in opposite directions.

The active part of the brain can be seen by the detectors inside the machine.

Alzheimer's disease or other forms of dementia can be determined with the help of scans of normal brains.

Hypothesizing the existence of a new particle is required to understand radioactive alpha decay.

Wolfgang Pauli predicted the existence of the neutrino, which was later found to explain the loss of energy during decay.
Antineutrinos are a form of antimatter.
Every known particle has an antiparticle.
Particles such as the positron and their funda mental interactions are investigated in this chapter.
By the end of this chapter, you will be able to understand the physics behind PET and the basic components of the universe.

The word "atom" means indivisible.

Physicists used to think that atoms were the smallest part of matter.
The internal structure of atoms was discovered in the late 19th century.
The discovery of radioactivity showed that the nucleus has a complex structure.
The investigation of black body radiation, photoelectric effect, and Compton scattering led scientists to conclude that light can be modeled as a photon.
Physicists identified four particles by 1930.
The proposal and discovery of so-cal ed antiparticles changed this view.

Ein stein's theory of special relativity was incorporated into quantum mechanics by Paul Dirac.

Dirac's model was able to predict the spin quantum number for the electron.
An unexpected com plication came along with this prediction.
Dirac's model predicted that free electrons had an infinite number of quantum states with negative total energy.
A free electron in a positive energy state should be able to transition to one of the nega tive energy states by emitting a photon.
All free electrons in the universe would transition to increasingly negative energy states.
This is not consistent with the behavior of electrons.

Dirac suggested that the negative energy states were occupied by a finite number of virtual electrons.

According to the Pauli exclusion principle, free electrons with positive energy can't transition into states that are electron states.

Dirac proposed that one of the virtual electrons in a negative energy state could be lifted out of its negative energy state and become a positive energy free electron.

Many quantum physicists disagreed with his model.
Dirac argued that the particles should exist.

Scientists used cloud chambers to determine the direction of the force that the mag netic field would exert on a positron.

The chamber was filled with a gas that was supersaturated with water or alcohol.

The cloud chamber was placed in a magnetic field.

The plane of the page was pointed into by the magnetic field.

The direction of travel of the particle was not immediately apparent.

It must be a negatively charged particle in order to curve if it entered the chamber from the top.
It must be a positively charged particle if it entered the chamber from the bottom.

The lower part of the path is less curved than the upper part.

The path was caused by a cular path.

The particle's speed decreased.

The positive charged particle must have traveled from the bottom of the chamber to the top.

If the path was caused by Anderson, the charge-to-mass ratio of the par- a positron moving from the bottom to the top ticle was the same as for an electron.

The cloud chamber trace must have been produced by one of Dirac's antielectrons.

There are few positrons in our world.

Positrons exist for very short periods.

During the interaction of a high-energy photon with matter, Positrons can be produced.

The photon cannot exist at rest, so you can't be sure of its mass on a scale.

The photon can produce both an electron and a posi at the same time.

We assume the spiral circles for the minimal energy calculation.

The wavelength is about 100 times the wavelength of an X-ray photon.

If the positron and electron produced are to possess some energy, then a higher energy gamma ray is needed.

The two particles should spiral in opposite directions if they occur in a magnetic field.

The photon no longer exists, so the momentum of the two particles should be the same as the original photon.

If we place the system in a magnetic field, the field exerts a force on the electron and on the positron in opposite directions.

They should spiral in opposite directions because of the force that the field exerts on them.
As their speeds decrease, the radius of their circular paths should decrease as well.

We now know that high-energy rays can be used to create electron-positron pairs.

Imagine that an electron and a positron meet and anni- be constant.

They must travel in opposite directions as they move towards each other.
There will be one or two in the figure.

This process requires a reaction equation.

S g is converted into two gamma rays.

The system must remain constant in this pair.

An electron-posi Electric charge is constant in both versions of the pro-tron pair.

The momentum of the photon process is not conserved.

There was a previous exercise that involved a positron.

We discussed the creation of a positron and an electron by a high-energy photon as well as the production of positrons by radioactive decay.
Let's look at another possibility.
There is an explanation of the decay of a neutron in nuclear physics.
A free neutron has a half life of about 10 minutes.

The electric charge of the system during this process is constant at 10 + 1 + 2.

The system's energy can be constant because the rest energy of the neutron is greater than the rest energy of the electron and protons.
An appropriate combination of the momenta of the three particles in the final state can equal the initial momentum of the system.
This process can happen without being in contact with the environment.

Since the rest energy of the neutron is greater than the rest energy of the pro ton, it seems that it can't be turned into a neutron.

The photon is absorbed by the protons and it decays into a quark, a positron, and a neutrino.

Without the proton absorbing a photon, decay can occur.

If some of the nucleus's energy is converted into the rest of the products, it can happen inside.
Carbon-11, nitrogen-13, oxygen-15, fluorine-18, and potassium-40 are examples of nuclei that can undergo decay.

In the process of becoming an argon nucleus, the potassium nucleus emits a positron and a neutrino.

Bananas are a good source of the potassium-40 nuclei in your body.

Posirons produced by this radioactive decay travel infinitesimal distances.

They are attracted to nega tively charged electrons and produce high-energy gamma rays, most of which leave the body.
This is the process that makes positron emission tomography possible.

Positron emission tomography is described in the chapter opening.

Pro ducing positrons is a function of the decay of the isotopes.

The detectors produce a pair of rays that move in opposite directions.

A three-dimen sional image of the active parts of the brain is created by combining many pairs of gamma rays.

The brain is active when a person performs a particular task.

Other particles have anti particles as well.

The negatively charged antiproton of the same mass as the positively charged one is part of the nucleus.
The antimatter counterpart of the neutron has other properties besides charge that it ate from the antineutron.
The photon is an example of an ally.
In this chapter, we look at why our universe is made of mostly ordinary particles.

We have learned about many types of interactions in our studies of physics.

In terms of fundamental interactions, nonfundamental interactions can be understood.
Friction is a representation of the interaction between the electrons of the two surfaces.
When speaking in general terms, we use the term "Interaction" rather than "force" because interactions can be repre sented using energy ideas.
The four fundamental interactions are the gravita tional interaction, the electromagnetic interaction, the strong interaction and the weak interaction.

If the objects are in motion with respect to each other, the interaction is electric.

The interaction is magnetic if the objects are moving in the same direction.
The inverse square of the distance between the two charged particles decreases the interaction between them.
Understanding the structure of atoms is dependent on the netic interactions between nuclei and electrons.

Because they are composed of charged particles, atoms participate in elec tromagnetic interactions with each other.

The formation of molecule and holding of liquids andsolids are contributed to by these interactions.

Atomic nuclei are made up of protons that repel each other and of neutrons that don't exert any force.

The force of attraction is greater than the force of attraction.

Pro tons and neutrons only exert their power on their nearest neighbors within the nucleus, which is a range of 3 to 10 m.

The interaction is weak.

Think of an analogy.

Humans use speech.

A sound wave travels through the air to another person when a person's larynx vibrates.
The sound waves hurt the other person's ears.
The electrical signal travels to the brain, where it is interpreted.

The field model for the interactions between electrical and charged objects was developed earlier in the text.

The idea was that charged particles would cause an electric field around them.
When a charged particle moves, the "signal" produced by that movement ripples through the electric field at a finite speed, and only when that signal reaches other charged particles does the force on them by the field change.

The field model we used to explain the mechanism behind the mag netic interaction predicted the existence of waves of visible light.

We showed how the model of netic waves could be used to explain the photo electric effect.

Physicists realized during the first half of the 20th century that the photon played a more central role.

The exchange of photon between electrical and charged particles is the mechanism behind the phe nomena.

The particle exchange mechanism has been successful in descri bing the weak and strong interactions, and it has had some success in describing the gravitational interaction.

When two particles interact, one emits a particle that is absorbed by the other, in each of the four fundamental interactions.
The photon is used in teraction.
Two electrons repel each other because one emits a photon, which travels at light speed to the other electron, where it is absorbed.
The absorbing electron recoils when the photon is absorbed.

There appears to be a serious problem with the particle exchange mechanism.

This helps us understand how the particle works.

The energy of an atomic-scale system can vary from instant to instant.

The mediator photons are called virtual because they are only small energy fluctuations in the system.

They don't have independent energy of their own that could cause a chemical change in your eye or an electronic detector.
Virtual particles can't be detected directly in any way.

The total energy of the interactions should be low.

We can now think of four fundamental interactions as ex change processes of four different mediators.

The strong and weak interactions have been discovered.
The four types of interaction mediators are summarized.

The interaction can be modeled as a photon exchange.

Massless particles travel at the speed of light.
The photon and anti photon are the same particle.

Gluons have zero electric charge and interact strongly with each other.

The strong interac tion has a short range.
There are different types of gluons.
The interaction of quarks is made possible by the ex change of gluons.

The interaction is weak because of three particles.

It is its own antiparticle.

The existence of these particles was predicted by a theory in the 1960s.
There were no particles found at the European Orga nization for Nuclear Research.

The theory predicted that the mediators have a large rest energy.

Producing them required the colliding particles to have high total energy.
protons and antiprotons were only accelerated to energies of tens of giga-electron volts, which was below the rest energy of the weak interaction mediators.

Technology had to catch up to confirm the existence of the mediators.

The graviton is predicted to travel to the photon at the speed of light, but the assumptions about what a quantum theory of gravity should be are incorrect.

The mass of a protons is what distinguishes them.

It has a mass of about 100 times that of a protons.

The mass explains why the interaction is short.
Even if they travel at a light speed, they can only travel an average of 10-18 m.

The interaction mediators were listed in kilo grams.

The values are so small in particle physics that this is not a common practice.
Mass is not usually used.
The 2 were measured in eV.
The mega-electron volt 11 MeV is the range for typical particle "masses".

1 eV equals 10-19 J.

The mass in mega ticles is determined by the number of electron volts and the number of protons.

Physicists have been discovering new particles using particle accelerators since the early 20th century.

The properties of these particles can be determined.
The particles are not stable.
Stable particles remain until they decay into other particles.

The mechanism behind the four fundamental interactions are the interaction mediators.

One cat egory of particles.

The weak, electromagnetic, and weakly interacting latinos interact through the weakly interacting latinos.

The electron neutrino is neutral.
The particles form a family of leptons.

The first member of a second generation was discovered in 1936.

The electron and the three neutrinos are stable particles.

Until 1998 physicists had no evidence to suggest that the neutrinos were anything other than zero.

The process is only possible if the neutrinos have zero mass.
Evidence from both particle physics and astrophysics shows that the three neutrinos have a rest energy of about 1 eV.
Experiments are being conducted to measure this more precisely.
They are difficult to detect because they don't interact via the strong interaction.

There are more examples of baryons than you know.

The lambda particle 0 and a set of four similar baryons known as the delta particles -, 0, +, and ++ were discovered in 1949-1952.
There were more baryons discovered in later years.

The first example of a meson was Hideki Yukawa's suggestion in 1935.

These particles were called mesons.
Combining rel ativity theory with quantum theory was the motivation for Yukawa's ideas.
The mass of Yukawa's mesons were 888-276-5932 888-276-5932 888-276-5932 888-276-5932s.
The correct properties of Yukawa's meson were discovered in 1947 by physicists, who called it a pi-meson or pion.

The internal structure of baryons and mesons is discussed in the next subsection.

The hadrons are not stable.
Their half-lives range from 610 s for the neutron to 24 s for the shortest lived.
Since 1950, hundreds of hadrons have been discovered.

The three quarks were caused by the large number of hadrons and the differences in their properties.

A new model of hadrons was independently proposed by Electron and his colleagues.

The hadrons are complex objects made of a small number of more fundamental particles that combine in different combinations to make all of the existing hadrons.

The elements of the periodic table can be made using different combinations of protons, neutrons, and electrons.

Experiments in which electron beams with energies of 25 GeV were shot into a sample of liquid hydrogen were explained by the idea of hadrons having internal structure.

The alpha particles shot by Rutherford's colleagues at gold foil atoms were similar to the scattered electrons.

The particles had to be charged with electricity.

The quark model only required three quarks to build hadrons.
There are now six quarks, all of which have been discov ered.

The quarks act weakly because they have nonzero mass.

Bars and mesons are bound states of three quarks and one antiquark, respectively.

There are three generations of leptons, each with a negatively charged member and a neutrino, for a total of six lep tons.

For a total of six quarks, the quarks fall into three generations.
There is a connection between the quarks and the leptons.

Particles have certain properties that determine whether they participate in certain interactions.

There are objects with zero electric charge.
It is not related to the colors we see with our eyes, but rather is a technical term that is used as a name for this property.
quarks have color charge because they participate in strong interaction A particle with a color charge can interact with another particle.

The neutral atoms have a net electric charge of zero and the particles that make up the protons and neutron are made of three quarks with different colors.

A protons has one red quark, one blue quark, and one green quark.

The effect of shining complimentary beams of red, blue, and green light on a surface is similar to this neutrality.

The surface glows white when it is color neutral.

quarks have a fractional electric charge.

There are two up quarks and one down posed of three quarks.

If down quark were converted to an up quark, this would be accomplished.

This sounds like one up and two down quarks.

The net charge is neutral.

An antineutron has properties besides charge that make it dif ferentiate from a neutron.

One up antiquark and two down antiquark make up an antineutron.

Our local world is made of electrons and two types of quarks.

There has never been an experiment that produced a quark in isolation.

The quark and the Tiquark have always been part of a hadron.
Attempting to split a protons into quarks by shooting a high-energy particle into it produces more quark-antiquark pairs.
New baryons and mesons are formed when these pairs combine with the original protons.
The strongest interaction is when the quarks are close together.
The reasons for the strong interaction ex hibits confinement are beyond the scope of this book, but the feature is crucial to explaining the structure and stability of the protons and neutrons in every atomic nucleus in your body.

The first versions were constructed in the first half of the 20th century.

The idea of special relativity and quantum mechanics were combined into a single model by physicists in the late 1940s.

The framework needed to describe the model was developed by Chen-Ning and Robert.

Several striking predictions were made by this model.

When the universe was smaller and hotter, all particles were massless.
As the universe cooled, it was predicted that the Higgs particle would interact with other particles, reconfiguring them into the form they are today.

Results from the first experiments began arriving at the end of 1974.

A meson composed of one charm and one anticharm quark.
The prediction of the J-psi particle was a success.

Scientists discovered the tau lepton and bottom quark between 1976 and 1979.

The top quark was discovered in the 1990s, and the tau 1096 Chapter 29 particle physics was discovered in 2000.

The discovery of a particle that may be the long-sought-after Higgs particle was announced in July of 2012

There is more work to be done to determine if the particle is the lightest of a series of Higgs particles predicted by theories that go beyond the Standard Model.

The matter of the universe is made up of quarks and leptons.

The quarks are in four fundamental interactions.
The strong interaction is what the leptons participate in.

There is a theory of strong interactions.

Some of the fundamental particles have nonzero mass because of the Higgs particle.

The Standard Model does not include the interaction.

How to combine this interaction with the Standard Model is a very challenging problem in physics.

Explain as many differences as you can between a protons and an electron using what you have learned about particle physics.

Almost all elementary particles have antiparticles.

The universe is expanding because distant galaxies are moving away from us.

The universe would get smaller, denser, and hotter if we reversed the expansion.

The universe would have been in a very hot and dense state a long time ago.

The model explained the red shifts of spiral nebulae.

The red shifts were greater for more distant nebulae.
The history of the universe is summarized below.

The average temperature of the universe was 1032 K at that time.

The temperature of the universe was about 1028 K. The volume of the universe increased by a factor of 1026 and settled into a more gradual expansion.
The density of the universe decreased during inflation.
The seeds of galaxy formation would later be found in areas where the density was slightly above average.

The density of the universe at a particular point differed from the average by only 1%.

The universe was made of hot particles.

The average temperature was so high that the random thermal motion of particles was very close to light speed.

There was a small excess of quarks over antimatter during this time because processes favored the production of matter over antimatter.
Understanding the details of these processes is an important goal of physics research.

The universe had cooled so much that quarks and gluons were able to form baryons.

There was an excess of quarks over antiquarks.
The temperature was not high enough to create antiproton pairs.
The baryons and antibaryons destroyed each other, leaving a small number of baryons.
Only one in 10 billion protons survived.
These are the protons that are found in the universe.
The thermal motion of particles was no longer relativistic after this.

The average density of the universe was close to sea level by a few minutes after the Big Bang, and the temperature had dropped to about a billion degrees K. For the first time, protons and neutrons were able to combine to form the simplest nuclei: deuterium, helium, and trace amounts of lithium.

Most of the protons were free as hydro Gen nuclei.

There was a ratio of hydrogen to helium nuclei.

The universe became cold enough for electrons to combine with nuclei to form neutral atoms.

The universe became transparent when this happened.
Prior to this, the uni verse was a plasma, an ionized gas of nuclei and electrons.
The particles do not travel freely.
The neutral atoms were able to travel freely when the universe was transparent.
The expansion of the universe has caused the red-shifted photons to have an effective temperature of about 2.7 K.

The ambient temperature of the present universe can be thought of as this.

The discovery of the CMB by Arno Penzias and Robert Wilson in 1965, was one of the most significant pieces of supporting evidence.

The model predicted the existence of this radiation.
Predicting the relative abundances of hydrogen, he lium, and lithium were made by the model.
Experiments are consistent with these predictions.

The dominant driver of the evolution was the interaction between the universe and the stars.

Some regions began contracting because of density fluctuations.
The formation of the first galaxies and stars happened 500,000 years after the Big bang.
Nuclear fusion processes produced heavier elements such as carbon, oxygen, iron, and gold, which were re leased into space to become planets.

The quarks that were part of the early universe are present on Earth.

During the life cycles of stars, the quarks formed complex nuclei and atoms.
Our bodies are composed of matter that was cre ated near the dawn of time and processed in stellar explosions before being part of us.

Two serious problems with the universe have yet to be solved in the 20th century.

The way stars move within them isn't explained by the size of the galaxies.
The universe is speeding up rather than slowing down, as the gravational interaction would predict.

In Chapter 4 we learned that Earth's speed around the Sun is deterred by the mass of the Sun.

The solar system's speed around the galaxy is determined by the total mass of everything that lies between the center of the galaxy and the center of the solar system.

There is too little visible mass to account for the motion of the galaxies relative to each other.

The observed motion of stars and galaxies is not being accounted for by the universe.

The first evidence of the problem was found in 1933 when astrophysicists looked at the Coma cluster.

The galaxies at the edge of the cluster were too fast to remain part of the clus ter.

Vera Rubin presented more evidence in the 70s.

She found that stars near the edge of a galaxy were traveling too fast to remain part of the galaxy.
The dark matter explanation began to become more accepted.

Scientists created experiments to detect a new form of unseen matter.

Direct detection of dark mat ter has not been accomplished.
Astronomers are more certain about what dark matter is than they are about what it is.
This is why it is cal ed "dark".
Dark matter can't be a dark cloud of protons or gaseous atoms because of the scattering of radiation passing through them.
There are several hypotheses for what this dark matter might be.
The names MACHOs and WIMPs are weakly acting massive particles.

These objects could be black holes, neutron stars, or brown dwarfs, which were not massive enough to achieve nuclear fusion and become stars.

Astronomers have been able to detect MACHOs using their effects on the light from distant ob jects.
When a MACHO passes in front of a distant object, the light bends around the MACHO and is focused for a short time, making the light appear brighter.
Over the course of 6 years, the MACHO Project has observed about 15 lensing events.
There must be more than one explanation.

In nature, these objects are more exotic.

The quarks and leptons that make up ordinary matter are not elementary particles.
Light is not absorbed or emitted by them and they are weak interacting.
Their mass is not zero.
neutrinos, axions, and neutralinos are not Standard Model particles and therefore need the Standard Model to be extended to accommodate them.

There are a lot of neutrinos in the universe.

The Standard Model does not give a zero mass to the neutrinos.
neutrinos have a rest energy range of 0.1 to 1.0 eV, a mil lion times smaller than the electron, according to recent experiments.
The dark matter was hoped to be if the neutrinos had enough mass.
It looks like neutrinos are too light for this.
Physicists don't know how to detect such a particle, but if it exists in sufficient abundance it could account for the dark matter.

The proposed axions have very small mass, no electric charge, and very little interac tion with Standard Model particles.

They would have been produced a lot in the big bang.
Current searches for axions include Earth-based laboratory experiments and searches in the halo of our galaxy and the Sun.
They have never been experimental.

A more precise understanding of the unification of interactions in grand unified 29.5 Dark matter and dark energy 1101 theories can be found in Supersymmetry, an extension of the Standard Model that doubles the number of elementary particles.

The detection of the super partners is one of the main goals of the Large Hadron Col ider.

The lightest superpartner is predicted to be weakly interacting.

The neutralino is the lightest superpartner and is predicted to have a mass of 100 to 1000 times the mass of a protons.
Physicists hope to detect neutralinos by using underground detectors, searching the universe for signs of their interactions, or producing them in particle accelerators.

The mystery of the missing matter of the universe is largely unsolved because none of the particles suggested as a solution have been detected.

Although the dark matter problem has been around since the 1930s, one thing that seemed irrefutable through the 20th century was that the massive objects in the universe would slow the expansion rate of the universe.

In 1998, two independent experiments using the Hubble Space Telescope showed that the universe is expanding more rapidly than in the past.
At the time, no one knew how to explain it.
Saul Perlmutter, Brian P. Schmidt, and Adam G. Riess won the physics prize in 2011.
The extensions of the Big Bang model could explain the expansion.

Physicists came up with a lot of ideas.

Suggest the existence of an energy-fluid that fills space and has a repulsive effect.

There is a new kind of field that creates this acceleration.

Let's look at the ideas.

Einstein included a term for a static universe in general relativity.

There was no evidence for the expansion of the universe at the time general relativity was written.
The general prediction was that the universe was unstable.
Einstein tried to allow general relativity to accommodate a steady state universe by introducing the cos mological constant.

Even though Einstein could have predicted the expansion of the universe, he couldn't accept it.

He considered this his greatest mistake.
The cos mological constant can be used to describe the accelerated expansion because it introduces a repulsive effect into the equation.
An idea that was discarded by Einstein 80 years ago has been resurrected to explain recent observations.

The second idea is a suggestion about what a constant is.

The density doesn't decrease even as the universe expands because it's a property of space.
This energy has a negative pressure.

This causes a repulsive effect on space.

The dark energy density remains constant as the universe expands.

As time passes, the attractive gravitational effect of the matter decreases while the repulsive gravitational effect of the dark energy remains the same.
The repul sion gets stronger as time goes on.
Astronomers have observed that the expansion is more rapid today than it was in the past.

The least radical idea is the third one.

The idea is that there is a better theory of the interaction that would make predictions even better than general relativity.

The new theory has to be constructed in such a way that it doesn't make predictions that are contrary to what has already been done.
Physicists have been unsuccessful in doing this.

Dark energy is the favorite of these three ideas.

The simplest of the vari ous versions represent the dark energy in general relativity as a constant.

Dark energy models have a problem because of a basic feature of quantum mechanics.

The model predicts that the elementary particles in the Standard Model are related to the associated quantum field.

The dark energy is the sum of the zero point energies of the quantum fields.
Physicists get a result that is 10120 times the observed value when they make estimates of what value these models predict.
It has been said that this is the largest disagreement between prediction and experiment in science.

Supersymmetry predicts a doubling of the types of dark matter and dark energy in the universe.

The particles have an associated quantum field.

The total dark energy density is zero.

The dark energy density is not quite zero, because we do observe an accelerated expansion, butOrdinary matter is not consistent with observations.

Supersymmetry is not present in this universe because none of the partner particles have been observed.

The idea of a smal but nonzero dark energy density is consistent with observation.
One of the goals of the Large Hadron Col ider is to produce some of these superpartner particles.

There is a dark matter and dark puzzle.

We know how dark energy affects the expansion of the universe.
Physicists explain patterns in a complete mystery.
Almost all of the total energy was served in nature.
The universe is not dark energy.
23% of the dark matter's rest energy has yet to be detected.
It is possible that one or both of the instruments could add up to 4% of the energy in the universe.

Only a small portion of the universe we live in is understood.

That is a very motivating realization.

4% of the contents of our universe are described in the models we have been building.

The nature of the remaining 98% of our universe is an unresolved problem.

In the late 1800s, the prime minister of England asked Michael Faraday what use he had for his idea.

It was not possible for Faraday to say.
Today, we have electric power generators, microphones, credit card readers, and electric guitar pickups.
They are based on the same thing.

The computing, com munication, and entertainment devices that are present in our everyday lives are a result of J. J. Thomson's understanding of the electron.

Physicists at MIT were studying microwaves in the 1930s.

Microwave radar is believed to have saved England in World War II.
We use microwaves to cook our food and they are involved in satel lite communications.

It's impossible to say for certain, but history suggests that it will.

Maybe it will lead to new sustainable energy sources, the ability to easily travel to other planets, or ways to protect life on Earth.
No one has yet come up with the most amazing future appli cations.

The particles have the same mass but different electric charge.

The photon is one of the particles that are their own antiparticles.
All interactions between objects are related.
Nonfundamental interactions can be understood in terms of these.
Every particle is a quark.

The energy in the universe is thought to be in two different forms.

There are clumps around the galaxies.

Dark energy is thought to be 23%Ordinary matter spread uniformly throughout the universe.

Billions of neutrinos pass through your body every second.

Free neutrons that are not part of a nucleus decay into mentary color protons and other particles with a half-life of about 10 minutes.

There are 0 particles.

An example of a long-range interaction and a short-range Mesons interaction can be given.
There is a difference between the mechanisms.

There are 0 particles.

Three examples of particles are elementary.

Three examples of those that are not physicists are currently known.

Determine the energy in the photon and focus.

The problem can be solved with an isolated electron and positron.

To show the problems, useNewtonian circular motion concepts.

A cloud chamber has a photon entering it.

The photon converts into an elec 3 inside the chamber.

Explain how a picture is taken.

Draw a picture of this situation.

A proton and an antiproton, both with negligible photon, electron, and positron tracks, annihilate each other to produce two photons.

A particle enters a cloud chamber.

There is a useful idea in the page about supersymmetry.

The fundamental interactions should be compared and contrasted.

The interaction is 39.

An electron and a positron are traveling in opposite directions.

There is a difference between a real particle and a virtual spect in the lab where the experiment is being performed.

The electron and positron col ide produce a 14.

Determine the wavelength of the photon.
Explain why you think they will have the same wavelength.

Our Sun converts 19 times a day.

Nuclear fusion creates hydrogen and helium.

The four important steps in the building of the Stan were annihilated with them.

The neutrinos have a very small 26.

Their way to Earth and beyond was unimpeded by the sun's core.

If we can measure the rate at which the sun shines.

There is an independent way to measure the nuclear re 31.

Our bodies have a lot of carbon, oxygen, and ni- higher the intensity of the Sun's radiation.

As hydrogen and helium were produced during the Big bang, these two methods should produce con.

The problem is solved by suggesting that 33.

The neutrinos can't dark matter.

The model predicted the number of neutrinos.

The problem with the solar neutrino was solved.

The nuclear reaction rate wasn't as high as it could have been due to the fact that nearly all the neutrinos are oscillated into other types.

In 1987 a supernova was found.

The reason might be different than thought.

Basic math skills are required for a study of physics at the level of this textbook.

The math topics are summarized in this appendix.

If you review this material and become comfortable with it as quickly as possible, you can focus on the physics concepts and procedures that are being introduced, without being distracted by unfamiliarity with the math that is being used.

In physics, exponents are used a lot.

It is said that 3 will be raised to the fourth power.
The number 34 is equal to 3, 3 and 3.
There are special names for operations when the exponent is 2 or 3.

Any quantity raised to the zero power is considered to be unity.

26 can also be written as 61/2.

To verify the result, look at the numbers 32, 33, and 1921272.

If you want to verify this result, you need to know that 24 is 16 and 34 is 81.