Jewels of Modern Physics

1
Jewels of Modern Physics

• Dallas Science Engineering Magnet High School-
  Warren Puckett

2
The Shining Jewels Lineup

• Nuclear Reactions / Radioactivity.
• Subatomic Particle Physics.
• Theory of Relativity.
• Time, Space and Dimensions.
• Cosmology, the Universe
• The Grand Reunification Theory.

3
The Mother of all Radiation

• After Becquerel discovered uranium exposed film,
  Marie Curie and her husband Pierre teamed to
  identify it as a atomic property and called it
  radioactivity.
• They won the 1903 Nobel Prize in Physics for the
  discovery. She died of leukemia in 1934.

4
Part 1 Nuclear Reactions and Radioactivity.

• All elements with atomic numbers (Z) gt 92 are man
  made transuranic radioactive atoms. Recall that
  Mass numbers are the number of protons plus
  neutrons and are called Isotopes.
• These isotopes spontaneously break down and
  transmutate into daughter elements and
  eventually become stable and non-radioactive.
• Energy and particles are released during this
  transmutation from the nucleus. Binding energy
  of holding the nucleus together is released at
  the rate of 1 amu (atomic mass unit) 1.6 x
  10-27kg 931 MeV. Thats a whole lotta volts !

5
Ernest Rutherford Discovered the Nucleus with the
?- Gold Foil Lab

• Ernest Rutherford discovered the nucleus in 1911
  and proposed the nuclear atom in which electrons
  surround a dense nucleus.
• He thought of the rest of the atom as empty
  space. But the electrons are negatively charged
  and the nucleus (protons) are positively charged.
  

6
Rutherfords Discovery of the Nucleus with the
Gold Foil Lab

• After the discovery that radioactive elements
  emitted rays of various types, physicists
  rushed out to shine beams of rays at different
  substances.
• Rutherford shone a beam of alpha particles,
  actually a beam of helium nuclei, at a thin sheet
  of gold foil. Most alpha particles behaved as
  expected, being deflected slightly or not at all.
  However, occasionally an alpha particle would be
  knocked almost backwards.

7
The Dense Nucleus makes itself Known in a Big Way

• Rutherford said, This unexpected result was
  equivalent to firing an artillery shell at a
  sheet of tissue paper and having the artillery
  shell bounce back!
• These results implied that the alpha particles
  would occasionally strike a small, incredibly
  dense object Rutherford had discovered the
  nucleus!

8
Rutherfords Gold Foil Lab
9
Rutherford Experiment CloseUp
10
Nuclear Reactions

• It was originally thought that the fundamental
  particle of matter was the atom and that atoms
  could neither be created nor destroyed.
• The discovery that atoms were made up of protons,
  neutrons, and electrons suggested the possibility
  that one type of atom could be transformed into
  another type of atom by adding or subtracting
  these fundamental particles.
• The reactions are either FUSION or FISSION.

11
Nuclear Fusion in the SUN !

• This happens every day as hydrogen isotopes are
  transformed into helium in the sun.
• In this type of equation, atoms are written in
  the form where X is the atomic symbol, Z is the
  atomic number of the atom (basically the number
  of protons an atom contains) and A is the mass
  number of the atom (the total number of protons
  and neutrons in the atom). AZX Example 21H is
  deuterium (heavy hydrogen)

12
Nuclear Fusion Formula

• Fusion is the nuclear reaction that combines the
  hydrogen isotopes into helium and releases huge
  amounts of energy as in the sun and stars.
• The equation is 21H 31H ? 42 He 10n E

13
Nuclear Fission Reaction

• Fission is the process of breaking down the
  nucleus by physical bombardment with neutrons of
  other decaying radioactive atoms.
• This is the type of reaction that is used in
  modern nuclear reactors and was the first Atomic
  Bomb mechanism.

14
Nuclear Fission Reaction

• As the first nucleus decays it gives off 3
  neutrons that strike other atoms and cause them
  to decay in a cascading reaction.

15
Nuclear Power Reactor

• A nuclear reactor is a complex heat exchanger
  with a steam driven generator.

16
The Infamous E mc2

• Under normal conditions, the total number of
  fundamental particles in an atomic reaction
  remains constant. The exception usually occurs
  in particle accelerators, black holes, and other
  unpleasant environments where there is enough
  excess energy to create new matter according to
  the Einsteins equation Emc2.
• An electron and a proton can also combine to form
  a neutron, which usually occurs only under very
  high pressures.

17
Mass and Energy are Equivalent

• Atoms form because it requires less energy for
  two protons and two neutrons to exist as a He
  atom than as separate particles.
• Since Einstein showed that mass and energy are
  equivalent (Emc2) we can directly measure the
  energy content of atoms by measuring their mass.

18
The Loss of Mass in Fusion gives BIG ENERGY !!

• Since He consists of two protons and two
  neutrons, we can estimate the mass of a He atom
  as 2(mn1.008665 au) 2(mp1.007825 au)
  4.032980 au
• However, the measured mass of the He atom is
  only 4.002603 au, a difference of 0.0030377 au.
  

19
Energy Release from Fusion

• This mass deficit may seem small, but if we use
  Einsteins formula to convert this mass into
  energy we get Emc2
• E (0.00303)(6.66x10-27 kg)(3x108m/s)2
  4.5 x10-13 Joules.
• This does not seem like a lot of energy, but
  remember this is for just one atom. The process
  of making a mole of He atoms releases 2.7x1011 J

20
Radioactive Decay The Three Products

• The weak nuclear force in nature is responsible
  for Radioactive Decay the spontaneous splitting
  of radioactive isotopes gradually into more
  stable elements and energy release.
• There are three decay products the Alpha
  particle, Beta particle and the Gamma Ray.

21
Decay Particles from Fission

• The Alpha particle (??) is the nucleus of the
  Helium atom. When it is given off the atomic
  number reduces by 2 and mass number by 4 and
  changes to a new element.
• The Beta particle (?) is a high speed electron
  from a neutron and leaving a proton that
  increases the atomic number by 1.
• The Gamma Ray (?) is an energy ray without mass.

22
Alpha Particle Decay

• Example When Uranium-238 decays by an alpha
  decay the result is a helium nucleus and a
  thorium-234 atom. Notice that as in any
  chemical equation, the summation of the mass
  before and after the reaction adds up.
• 23892 U ? 42He 23490Th

23
Beta Particle Emission

• The beta particle is actually a high speed
  electron. It originates from the decay of a
  neutron (0) in the nucleus into a proton(1) and
  an electron(-1). This causes a change of 1 to
  the atomic number and a ZERO change to the Mass
  number. Remember the electron is 1/1830 the mass
  of a proton.
• Example If an carbon-14 decays into a
  nitrogen-14 the formula looks like
• 146C ? 147N e- a neutrino

24
Gamma Emission

• The gamma emission is a photon of very high
  energy. The decay of a nucleus by emissions of a
  gamma ? ray is much like emission of photons by
  excited atoms. Except this time it is an excited
  nucleus with a lot more energy. Since it is only
  energy, there is NO CHANGE in mass or charge.
  Gammas are deadly ionizing radiation. Neutron
  bombs work from this mechanism.
• AZ N ? AZ N ?

25
Radioactive Half Life

• The half-life of a radioactive material is the
  amount of time it takes for ½ of the mass of a
  radioactive isotope sample to decay spontaneously
  into new material. Two versions of the formula
  are ?N - ?N ?t and N Noe-?t where ? is
  the decay constant and N is the number of
  radioactive nuclei. The shortcut formula is T ½
  0.693/ ?
• Half-lives can range from a fraction of a second
  to billions of years. Carbon-14 has a ½ life of
  5730 years while U-238 has a 2.3 billion year
  half life.

26
II. Sub-Atomic Particle Physics

• By the middle of the 1900s it was thought that
  all there was inside an atom had been found and
  we had the complete picture.
• Then with the invention of the particle
  accelerator we had 60 sub-atomic particles by the
  mid 1960s.
• Today, we know of about 200 particles smaller
  than the proton, neutron and electron that are
  called Elementary Particles.

27
The Sub-Atomic Particles Standard Model
28
Structure within the Atom
29
Various Sub-atomic Particles
30
Lepton and Quark Properties
31
Quarks

• Special Combinations of Quarks make up Protons,
  Neutrons and other subatomic particles.

32
How Small is Sub-Atomic?
33
Cosmic Rays

• Cosmic rays (CR) are not really rays at all, but
  PARTICLES.
• Cosmic ray particles are traveling very close to
  the speed of light, and the most energetic
  particle ever observed had about 20 Joules of
  kinetic energy (equivalent to the energy of a
  fast shot ball).
• They originate from space, being produced by a
  number of different sources, such as the Sun,
  other stars, and more exotic objects, such as
  supernova and their remnants, neutron stars and
  black holes, as well as active galactic nuclei
  and radio galaxies.

34
Particle Accelerators let us Dissect into the
Smallest Parts of the Atom.

• Particle Accelerators are machines that smash
  protons and electrons into each other at high
  speeds to see the things that come out.
• They are typically big underground circular
  tunnels like the one shown here.

35
Ring Particle AcceleratorsFermi Lab Chicago
Illinois
36
Fermi Lab Magnets inside the underground ring

• The magnetic ring pathways and a picture of them

37
Straight Line Accelerator Stanford Linear
Accelerator in California
38
Atlas Experiment
39
The Detector

• The collision happens inside the Detector.
• Instruments measure what comes out of the
  collisions inside it.

40
A Subatomic Particle Detector

• The instruments in this detector will be used to
  detect the smallest and most elusive particles of
  matter in the universe.

41
The Collision

• The results of some collisions provide many
  subatomic events and sometimes more questions
  than they do answers.
• Such as- What is Mass ?

42
Computer Enhanced Collision Results show Many
Different Things

• The lines in the picture show the many different
  particles that arise when the collision is high
  enough energy.

43
Quarknet/ SMU FERMI Lab Outreach
44
II. Theory of Special Relativity

• Effects of Relativity
• Principle of Simultaneity
• Time Dilation
• Length Contraction.
• Mass Increase
• Mass and Energy

45
Einsteins Theory of Special Relativity Its a
Speed Thing

• Newton's laws of motion give us a complete
  description of the behavior moving objects at low
  speeds. The laws are different at speeds reached
  by the particles in accelerators.
• Einstein's Special Theory of Relativity describes
  the motion of particles moving at close to the
  speed of light.
• For particles moving at slow speeds (very much
  less than the speed of light), the differences
  between Einstein's laws of motion and those
  derived by Newton are tiny. That's why relativity
  doesn't play a large role in everyday life.

46
Theoretical Basis of Special Relativity and Its
Effects

• Einstein's theory of special relativity results
  from two statements -- the two basic postulates
  of special relativity
• 1.      The speed of light is the same for all
  observers, no matter what their relative speeds.
• 2. The laws of physics are the same in any
  inertial (that is, non-accelerated) frame of
  reference that is either at rest or moving in a
  straight line at constant speed.

47
Principle of Simultaneity

• Two events which are observed to occur
  simultaneously at different points in one frame
  of reference are said to happen simultaneously.
• If one observer is moving relative to another and
  the same two events happen, they will not appear
  simultaneously to both.
• This viewpoint of different viewpoints is
  important for observing the other effects of
  relativity.

48
The Railroad Cars struck by Lightning
Simultaneously

• When the railcars are side by side and lightning
  strikes at A2 and B2, then both O1 and O2 see it
  simultaneously.
• If the cars are moving separate then O1 and O2
  will see the lightning strikes at different
  times even though they happened at the same
  time.

49
Effects of Relativity Time Dilation

• Time Dilation-The faster you go, time slows down.
  If you could move with the speed of light,
  theoretically time would stop.
• If someone went on a 4.5 Earth year round trip
  space voyage at near light speed (0.95c), when
  they got back they would have only aged 1.4 years
  on the spacecraft
• The formula is ?t ?to / 1-(v/c)21/2
• This was proven on Apollo 11 when the round trip
  to the moon at 25,000 mph lost 1.3 seconds on
  an atomic clock of Cesium 133.

50
Time Dilation Diagram
51
Effects of Relativity Length Contraction

• As constant near light speeds slow down time, the
  length will contract as observed by someone at
  rest.
• The formula is L Lo1-(v/c)21/2

52
The Paintings Contraction

• As the painting travels faster its length
  contracts in the direction of travel.
• The height remains unchanged because it is not in
  the plane of travel.

53
Effects of RelativityMomentum andMass Increases
as Speed Increases

• As your speed increases to light speed both your
  mass and momentum increase exponentially.
• The formulas are

54
Effects of Relativity Ultimate Speed The
Speed of Light

• These effects add up to a mathematical maximum
  speed in the universe Light Speed
  ( 3 x 108 m/s)
• As an object travels faster its mass increases to
  where velocity c then mass is infinite and
  would require infinite energy to move. This is
  not possible ( for todays technology).

55
Effects of Relativity Energy and Speed of
Light

• The famous equation of E mc2 is only for resting
  objects. When speed is added to the problem the
  equation becomes Emc2 KE
  where KE ½ mv2.
• Notice that since mass ? ? as v ? c, then the
  energy required to push the mass at that speed is
  also infinite. Different theories abound about
  what would happen at c.

56
Einsteins General Relativity Theory

• In his General Theory of Relativity, Einstein
  tackled the problem of accelerating reference
  frames and developed a theory of gravity.
• The Principle of Equivalence says no observer can
  distinguish between a gravitational field and an
  accelerating field. This refers to inertial mass
  and gravitational mass being the same in space.
• Gravity is the result of the bending of space and
  time by mass. The bending of light in stars
  proves this concept. This gives rise to the idea
  of Black Holes.

57
Gravity Bending Time Space

• A Gravity Lens bends the light around obstacles
  creating the circular lens effect.

Einsteins original notes on gravity bending time
space and light.
58
Black Holes

• When very large neutron stars go through their
  life cycle and collapse in on themselves they
  create small super massive cores that bend space
  and time. They have such great attraction that
  all matter and even light is attracted into them.
  
• This absence of luminance is seen as a black area
  in space. We call this a Black Hole.

59
Black Hole Hubble Photos
60
A Black Hole in The Milky Way
61
Black Hole Diagram
62
Four Dimensional- Time and Space

• These seemingly dissimilar factors have been
  proven to be intimately connected through special
  relativity with time dilation and length
  contraction. One can be exchanged for another.
• Every object or event is defined by 4 properties
  3D space and time.
• Some scientists suggest that there are other
  dimensions and possibly other parallel universes.

63
Four Dimensions in Action
64
Cosmology and The Universe

• Cosmology is the scientific study of the large
  scale properties of the Universe as a whole.
• It endeavors to use the scientific method to
  understand the origin, evolution and ultimate
  fate of the entire Universe.
• Like any field of science, cosmology involves the
  formation of theories or hypotheses about the
  universe which make specific predictions for
  phenomena that can be tested with observations.

65
The Big Bang Theory

• The prevailing theory about the origin and
  evolution of our Universe is the Big Bang
  Theory where Genesis starts with an explosion of
  unbelievable size.
• The Big Bang theory makes definite predictions
  for the structure and evolution of the universe
  that depend on the nature and amount of matter in
  the universe.

66
Big Bang Timeline
67
The Big Bang Theory Evidence

• Edwin Hubble's 1929 observation that galaxies
  were generally receding from us (Red Shift-
  Doppler Effect) provided the first clue that the
  Big Bang theory might be right.
• The Big Bang Theory predicts that these light
  elements, Hydrogen, Helium and Lithium should
  have been fused from protons and neutrons in the
  first few minutes after the Big Bang.
• The early universe should have been very hot. The
  cosmic microwave background radiation (discovered
  in 1964) is the remnant heat leftover from the
  Big Bang.

68
The Grand Reunification Theory

• The basic premise of grand unification is that
  the matter and forces in the universe were
  unified at the beginning of the Big Bang
  Reaction.
• This was Einsteins last project and he did not
  live long enough to finish it. Experimental
  evidence is currently incomplete but so far
  points toward a successful completion of the
  puzzle.
• In the beginning the energy was in a state of
  being (called symmetry) that is a combination of
  all its parts. This state went through phase
  changes to produce the matter and forces we see
  today.

69
The Grand Reunification Chart
70
The Four Fundamental Forces
71
The 11 Great Unanswered Questions in Physics

• 1. What is dark matter?
• 2. What is dark energy?
• 3. How were the heavy elements from Fe ?
  Uranium made?
• 4. Do neutrinos have mass?
• 5. Where do ultrahigh energy particles come from?

72
Physics 11 Great Unanswered Questions continued

• 6. Is a new theory of light and matter needed to
  explain what happens at high energy and temp?
• 7. Are there new states of matter at ultrahigh
  temperatures and densities?
• 8. Are Protons unstable?
• 9. What is gravity?
• 10. Are there additional dimensions?
• 11. How did the universe begin?

73
Credits to

• Giancoli, Hecht, Quarknet, Fermi Lab, NASA, all
  scientists throughout time.