2 Start Simple-Grow complex Start simple-Get ComplexFrom a sunbeamA World made from lightLight Gets HeavyDrops of lightDrops to puddles, to streams, to rivers, to oceans.Making a cake from scratch (totally from scratch)
3 Chemistry: A Simple Beginning Building Blocks By starting from one or a few building blocks, a multitude of things can be built.Legos, tinker-toys, kinetixPennies, beer cans, toothpicks, popsicle sticks, dominoes, sandBricks, logs, glass are traditional building materials.
4 Chemistry: A Simple Beginning Building Blocks By starting from one or a few building blocks, a multitude of things can be built
5 It’s all about building blocks CHEMISTRYIt’s all about building blocks
9 All built from a few building materials: Metal, glass, cement, plastic, & wood.
10 Let’s make a cake from scratch (totally from scratch) Personal familiarity with proton is acidic tastes.Neutron, twice as heavyElectron- all that you see.Proton Neutron Electron
11 Drops of LightA long time ago light turned into drops of matter. It only happens under extreme conditions. But you have probably seen the reverse- matter turning to light. It’s seen during a nuclear explosion.
12 E = mc2 E = 1 kg x (300,000,000 m/s)2 E = 9x1016 joules 1 joule = 1 watt for 1 secondE = 9x1016 watts x sec x kilo x 1 hr sec E = 25,000,000,000 kilowatt-hrs Arizona produced & used 58,000,000,000 KW-hrs in 1999 About half a year to produce enough energy to create the mass used in a cake (1kg). Cost = about 3 billion dollars
13 High energy light (photons) are needed to create matter. 2 or 3 volts can produce visible light, but that’s not high enough energy. We need higher frequency light, which has higher energy photons.
14 The picture tube (also called CRT) that’s in your television or computer monitor creates light by accelerating electrons with 30,000 volts of electricity to slam into the front of the monitor. This light has more energy but not enough.
15 Xray Machine100,000 to 200,000 volts of electricity to accelerate electrons to strike a metal plate. When the electrons come to a halt, they give up their energy as high energy light called xrays. But this light still doesn’t have the energy to create matter.
16 The voltage needed to create an electron is about one million volts The voltage needed to create an electron is about one million volts. This is the voltage that creates a bolt of lightning. This voltage pushes electrons from the sky to the ground, but the electrons are slowed down by the air. If they weren’t, it would be possible that two electrons accelerated by a million volts striking the ground would give off light of enough energy to create a new electron.
19 Positron (anti-electron) Electron and anti-electron (positron) created when high energy gamma rays with energy of 1 million volts collide.
20 ProtonAnti-ProtonProton (+) and anti-proton (-) created when high energy gamma rays with energy of 938 million volts collide.
21 Proton Quarks Anti-quarks U D U D Neutron D U +2/3 -1/3 Quarks of six “flavor” or “colors” and their anti-quarks are created when high energy gamma rays with energy of about 300 million volts collide.
31 C O Hydrocarbons Gasoline Diesel-12 O Oil-20 Plastic 1000s C O O C O O
32 C Carbohydrate O Glucose Ribose Glycerin C C C O C O O O C O H H H H H
33 A photon (packet) of light energy has an energy, E (Joules), proportional to its frequency, f (sec^-1). The constant of proportionality is Planck's constant, h (Joule-sec). So: E = h*f. The value of h = 6.63*10^-34 so you can see that any single photon carries very little energy.Anti-Proton annihilation 938 MeVIn order to create the anti-proton, protons were accelerated to very high energy and then smashed into a target containing other protons. Occasionally, the energy brought into the collision would produce a proton-antiproton pair in addition to the original two protons. This result gave credibility to the idea that for every particle there is a corresponding antiparticle.During the first four seconds of the universe, matter formed by pair production.
34 Two photons can collide to form a particle-antiparticle pair if the energy of each photon is greater than the energy equivalent (E = mc2) of the particle or antiparticle. For instance, a proton has mc2 of joules. Two photons, each an energy greater than this value, can collide to form a proton-antiproton pair. This process is known as pair production. Conversely, a particle and antiparticle can collide to form a pair of photons. For instance, a proton and antiproton colliding at a low relative velocity will produce a pair of photons, each with an energy of joules. (This is a high energy for a photon, corresponding to an extremely energetic gamma-ray.) The process of converting a particle-antiparticle pair to photons is known as annihilation.When the universe was less than second old, the photons of the cosmic background were so energetic, proton-antiproton pairs were continuously being formed by pair production. However, the proton-antiproton pairs were also continuously being destroyed by annihilation.At an age of seconds, the temperature of the universe dropped below 10 trillion degrees Kelvin. At this temperature, the average photon energy is joules, the energy equivalent of a proton or antiproton. Pair production of protons stops (the photons have dropped below the necessary energy), but the annihilation of protons continues.Thanks to a subtle bias in the laws of physics, however, the production of protons is very slightly favored over the production of antiprotons. For every billion antiprotons, there will be a billion and one protons. So here's the situation after pair production stops: 1 billion and 1 protons + 1 billion antiprotons -> 2 billion photons + 1 proton We now have a situation in which the universe contains lots of photons, a few protons, and no antiprotons. We state that the protons have ``frozen out'', since they are no longer being produced or annihilated.Neutrons are about as massive as protons, so they freeze out at the same time as protons. Electrons and positrons, however, since they are only 1/2000 as massive as a proton, are produced and annihilated continuously until the universe drops to a much lower temperature.
35 Protons are attracted to electrons Protons are attracted to electrons. But protons repel protons and electrons repel electrons.This pulling and pushing accounts for all compounds created from the elements.
36 The element vs. atomGold is the element that is yellow and shiny.A gold atom is an atom that must have 79 protons. It also has 79 electrons. And 117 neutrons.
37 Atoms are not stupid nor are the smart Atoms are not stupid nor are the smart. But they can do things that seem smart.The forming of crystals is just one. They can form geometric shapes that can bend light in many ways.
38 What kinds of quarks are protons and neutrons made of What kinds of quarks are protons and neutrons made of? What was the old name for the Top and Bottom quark?Protons are made of two Up and one Down quark. The neutron is made of two Down and one Up quark. The Up quarks have a 2/3 positive charge and the Down has a 1/3 negative charge. Fractional charges are a pretty funny concept, but remember we (humans) made up the unit of charge that a proton has, so its very possible that there could be a smaller division of charge. If you add those charges you will see that sum is positive one for the proton and 0 for the neutron.Truth and Beauty quarks were called T and B when originally proposed, to be Top and Bottom in analogy with the nucleon quarks that had just been renamed the Up and Down quarks. (Originally P and N had been used, but this led to confusion with the nucleons.) Very soon after the proposal T and B was made, somebody, maybe MGM, decided to call them Truth and Beauty. This nomenclature remained standard for several years. The term Beauty is still often used for the B quark. The Cornell accelerator was called a "Beauty factory" which sounds much nicer than a "Bottom factory." After the B was discovered and years went by without the T, people started to say "the quark model has no truth." This was true, but did not sound nice. This incident caused the name Truth to be dropped and Top and Bottom again became standard. Now that the T quark is well established, the name Truth can safely be brought back, but I don't know if it will, since MGM does other things now.A Theoretician, who formulates ideas or theories, suggests that to explain certain natural phenomena, a certain particle must exist. Other scientists and experimentalists do experiments to look for that particle. In the early 1960's a theoretician, Murray Gell-Mann, proposed the quark theory. He named the quarks then even though they had never been observed. It took experimentalists nearly 30 years to find proof of the existence of all six quarks. The Top was the last quark discovered in two experiments called CDF and D0 at a sister lab to Jefferson Lab, Fermilab, outside Chicago. They announced their discovery in April, Many particles have been discovered by accident during an experiment looking at something else. The experimenter then gets to name that particle, therefore a lot of particles have awfully silly names.
39 When a neutron undergoes beta decay, it becomes a set of three particles: proton, electron, anti-neutrino. The number of quarks is still the same: three. The number of leptons is the same: zero. An electron has a lepton number of +1. An anti-neutrino has a lepton number of -1. It is an anti-lepton.The neutron is about 0.2% more massive than a proton, which translates to an energy difference of 1.29 MeV.Universe is mostly light (photons ) "...it was light that then formed the dominant constituent of the universe, and ordinary matter played only the role of a negligible contaminant." Reminiscent of "Let there be light...".
40 Pair Production : Pair production is the formation or materialization of two electrons, one negative and the other positive (positron), from a pulse of electromagnetic energy traveling through matter, usually in the vicinity of an atomic nucleus. Pair production is a direct conversion of radiant energy to matter. It is one of the principal ways in which high-energy gamma rays are absorbed in matter. For pair production to occur, the electromagnetic energy, in a discrete quantity called a photon, must be at least equivalent to the mass of two electrons. The mass m of a single electron is equivalent to 0.51 million electron volts (MeV) of energy E as calculated from the equation formulated by Albert Einstein, E = mc2, in which c is a constant equal to the velocity of light. To produce two electrons, therefore, the photon energy must be at least 1.02 MeV. Photon energy in excess of this amount, when pair production occurs, is converted into motion of the electron-positron pair. If pair production occurs in a track detector, such as a cloud chamber, to which a magnetic field is properly applied, the electron and the positron curve away from the point of formation in opposite directions in arcs of equal curvature. In this way pair production was first detected (1933). The positron that is formed quickly disappears by reconversion into photons in the process of annihilation with another electron in matter.
41 Presto! Light Creates Matter As nuclear bombs and many physics experiments show, turning matter into light, heat, and other forms of energy is nothing new. Now a team of physicists has demonstrated the inverse process--turning light into matter. In the 1 September Physical Review Letters, the team describes how they collided large crowds of photons together so violently that the interactions spawned particles of matter and antimatter: electrons and positrons (antielectrons). Physicists have long known that this kind of conjuring act is possible, but they have never observed it directly.Working at the Stanford Linear Accelerator Center (SLAC), the 20-physicist collaboration focused an extremely intense laser beam at a beam of high-energy electrons. When the laser photons collided head-on with the electrons, they got a huge energy boost, much like ping-pong balls hitting a speeding Mack truck, changing them from visible light to very high-energy gamma rays. These high-energy photons then rebounded into the path of incoming laser photons, interacting with them to produce positron-electron pairs.Such particle pairs are often spawned in accelerator experiments that collide other particles at high energies, and photons produced in the collision are the immediate source of the pairs . But in those experiments, at least one of the photons involved is "virtual"--produced only for a brief moment in the strong electric field near a charged particle of matter. The SLAC experiment marks the first time matter has been created entirely from ordinary photons.Princeton University physicist Kirk McDonald, a spokesman f or the multi-institution collaboration, says the result, which was completely expected, is only the first step in using powerful lasers and electron beams to explore the interactions of electrons and photons, described by the theory known as quantum electrodynamics (QED). "We're exploring new regimes and trying to map out the basic phenomena," he says. Physicist Tom Erber of the Illinois Institute of Technology is pleased at the prospect of such experiments. "Hopefully, this will open the door to future experiments which will approach [new] tests of QED."
42 REAL PHOTONS CREATE MATTER REAL PHOTONS CREATE MATTER. Einstein's equation E=mc2 formulates the idea that matter can be converted into light and vice versa. The vice-versa part, though, hasn't been so easy to bring about in the lab. But now physicists at SLAC have produced electron-positron pairs from the scattering of two "real" photons (as opposed to the "virtual" photons that mediate the electromagnetic scattering of charged particles). To begin, light from a terawatt laser is sent into SLAC's highly focused beam of 47-GeV electrons. Some of the laser photons are scattered backwards, and in so doing convert into high-energy gamma ray photons. Some of these, in turn, scatter from other laser photons, affording the first ever creation of matter from light-on- light scattering of real photons in a lab. (D.L. Burke et al., Physical Review Letters, 1 September 1997.)
43 LET THERE BE MATTER: IN THE BEGINNING, (SFX: FANRARE) THERE WAS E=MC2 LET THERE BE MATTER: IN THE BEGINNING, (SFX: FANRARE) THERE WAS E=MC2. A NEAT LITTLE EQUATION BY EINSTEIN WHICH SAYS THAT ENERGY AND MASS ARE EQUIVALENT. SCIENTISTS REALIZED IN THE 1930'S THAT MCDONALD: In principle any kind of mass could be transformed into energy and vice versa. KIRK MCDONALD IS A PHYSICIST AT PRINCETON UNIVERSITY AND HE SAYS THAT MATTER TURNS INTO LIGHT ALL THE TIME WHEN ATOMS COMBINE OR PULL APART. BUT TAKING A BIT OF LIGHT AND TURNING IT INTO A PARTICLE--THAT'S TOUGH. AND IT CERTAINLY SOUNDS WEIRD TO MOST OF US--THIS IDEA OF JUST CREATING SOMETHING OUT OF THIN AIR. OVER 60 YEARS SINCE SCIENTISTS FIRST THOUGHT IT COULD BE DONE, MCDONALD IS ONE OF A GROUP OF SCIENTISTS THAT HAS FINALLY SUCCEEDED. MCDONALD: "In some sense we are one of the slowest confirmations of an idea in science this century." BUT THAT'S BECAUSE THE EXPERIMENT TOOK VERY MODERN TECHNOLOGY. IT TAKES A HUGE AMOUNT OF ENERGY TO MAKE A TEENSY PIECE OF MATTER. TO MAKE AN ELECTRON, MCDONALD NEEDED AS MUCH ENERGY AS IS IN ONE MILLION PHOTONS. AND THEN THE PHOTONS HAVE TO SOMEHOW BE SQUASHED TOGETHER INTO ONE POINT. MCDONALD: "Ordinarily, particles of light. . .don't interact with one another. . . if light coalesced the sun wouldn't shine, it would never get here it would all clump together into some other form of matter." GETTING PHOTONS WITH ENOUGH ENERGY REQUIRES USING PARTICLE ACCELERATORS. AND GETTING THE PHOTONS ALTOGETHER INTO A SINGLE POINT REQUIRES CRASHING THE PHOTONS INTO EACH OTHER WITH SOME PINPOINT LASER TECHNIQUES. IT'S ALL COMPLICATED AND EXPENSIVE ENOUGH THAT YOU'RE NOT GOING TO SEE ANYONE CREATING MATTER OUT OF THIN AIR ON A REGULAR BASIS ANY TIME SOON.The Higgs boson, sometimes called the God particle, was first predicted in the 1960s by the British physicist Peter Higgs. The Higgs mechanism for giving mass to particles was actually first proposed in the context of solid state physics to explain how particle-like structures in metals can act as if they had an effective mass.The Higgs boson itself has mass. Theory gives an upper limit for this mass of about 200 GeV (update: As of 10 June 2004, best estimate is 96—117, upper limit is 251 (95% confidence). As of 2002, particle accelerators have probed energies up to 115 GeV. While a small number of events have been recorded that could be interpreted as resulting from Higgs bosons, the evidence so far is inconclusive. It is expected that the Large Hadron Collider, currently under construction at CERN, will be able to confirm the existence of Higgs bosons.
44 Research supported by the Office of Science is making progress in the intense search for the Higgs boson, which may be the force that finally explains why some fundamental particles have mass, but others do not. Higgs is the last undiscovered component of the Standard Model, physicists' current theory of matter and the forces of nature. The model includes three families of particles called quarks and leptons; bosons carry forces between other particles. The Standard Model predicts a relationship between the masses of the Higgs boson, the W boson (which carries the "weak force"), and a particle called the top quark. Precise measurements of the properties of the top quark and W boson at Fermi National Accelerator Laboratory and the Zo at the Stanford Linear Accelerator Center in the 1990s significantly narrowed the predicted range for the mass of the Higgs boson. The SLAC experiments obtained what remains the most precise prediction of the mass of the Higgs, hinting that it should be light.Scientific Impact: These experiments told scientists what mass range to seek in direct measurements of the Higgs boson; when the Higgs is found, comparisons of direct and indirect measurements will provide a strong test of the Standard Model. The results also suggest that the Higgs might be within reach of existing accelerators.SLD Event Display of a Z particle decaying to two quarks. An electron and positron travelling in opposite directions (perpendicular to this page) collided at the center of the detector and annihilated, creating a Z. The Z subsequently decayed to a quark and anti-quark, which then hadronized to form two jets of particles traveling in opposite directions. These are the two jets of green tracks seen in this projection