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What IS Matter ?

What IS Matter ?. Matter is all the “stuff” around you!. Here’s the picture we’re going to uncover (not all today though). Matter. Hadrons. Leptons. Forces. Baryons. Mesons. Charged. Neutrinos. Gravity. Strong. Weak. EM. Quarks Anti-Quarks.

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What IS Matter ?

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  1. What IS Matter ? • Matter is all the “stuff” around you! • Here’s the picture we’re going to uncover(not all today though) Matter Hadrons Leptons Forces Baryons Mesons Charged Neutrinos Gravity Strong Weak EM Quarks Anti-Quarks

  2. We’re going to work our way from the largest size objects which we know about to the smallest size objects which we know about

  3. Where does all this come from? • The universe is a very big place! • It is filled with galaxies much likeour own, the Milky Way • There are likely ~100 billion of themwhich we can “see”. • Each of these galaxies contain around100 billion stars. • Our Milky Way galaxy is simply one of them. • Our Sun is just one of the 10,000,000,000,000,000,000,000 stars in the universe! Fig: Small section of the universe, from the Hubble Space Telescope (HST)

  4. Our Galaxy: The Milky Way • How big is the Milky Way (M.W.)? • Its radius is about 100,000 light years ! • How far is a light year (l.y.)? • It’s the distance light travels in 1 year! Us (Our Solar System) So, 1 l.y. = 5,870,000,000,000 miles (5.9x1012 mi.) ! • So, the M.W. Galaxy radius is about600,000,000,000,000,000 (6x1017) milesin radius!

  5. The Center of our Solar System: The Sun • At the center of our solar system is our star, the Sun • It’s diameter is ~100 times that of the earth, which implies you could fit ~1,000,000 earths inside the sun! • It’s is ~330,000 times as massiveas the Earth

  6. The Sun (cont) • It is a thermonuclear reactor. Inside the sun, hydrogen is being converted into helium. • In this process, energy is released in the form of heat, electromagnetic waves (UV, visible light), neutrinos, etc. • It’s surface temperature is ~10,000 OC; other parts of thesun can be as hot as 15,000,000 OC. So, it’s HOT !

  7. Our Solar System: The Planets Earth is at about 94 million milesfrom the Sun 3.6 billion miles

  8. The Planets • The figure shows relative sizes of the planets • Distances between planetsnot drawn to scale • Astronomically, we’re pretty tiny! 3.6 billion miles Pluto Earth (Diam ~ 25000 mi.) Saturn Neptune Uranus Jupiter Sun

  9. The Earth Mass : 6 x 1024 [kg]Radius: 6.4 million meters Africa

  10. Ahhh, and finally we’re back home • So, to set the scale: • From here to California2,500 miles • From here to the next closest star25,000,000,000,000 miles (25 trillion miles) • Like traveling back and forth toCalifornia 10 billion times Not very practical to get even to the next closest star!

  11. Exercise The next closest star is about 25 trillion miles away. How long would it take an spacecraft moving at 20,000 miles/hr to get to this star? Well, every hour the spacecraft goes 20,000 miles (2x104 miles) So, the time it would take would be: (25 x 1012 [miles]) / 2x104 [miles/hr] = 1.25 billion hours = 52 million days = 143,000 years = 1,430 centuries!

  12. And then there’s US ! • We’re very small compared tothe vast universe! • However, there are thingswhich are a lot smaller than us. • Well, let’s keep going!

  13. 0.0002” What are we made of ? • We’re made of cells whichcontain DNA. - Different cells serve different functions in your body. • Cells contain a nucleus, which holds your DNA ! • And the DNA is simply a complex chain of moleculeswhich contains your genetic code! • And what are molecules made of ?

  14. The Elements • Molecules are complex structures of the elements

  15. The Atom Electrons Nucleus 5x10-15 m 0.0000000002 m (2 x 10-10 m)

  16. Atoms and Space Approximately what fraction of the volume of an atom does thenucleus consume? Assume that the nucleus and the atom can be approximated via spheres with the radii given below? Use the following data. • The radius of the nucleus is ~ 5x10-15 [m]. • The electrons orbits at a radius of ~ 2x10-10 [m] • Ignore the electrons size, as it is unimportant. • The volume of a sphere is (4/3)pR3.

  17. Answer… • a) First find the volume of the entire atom • Volume = (4/3)*p*(2x10-10)3 = 3.4 x 10-29 [m3] • b) Now find the volume which contains the nucleus. • Volume = (4/3)*p*(5x10-15)3 = 5.2 x 10-43 [m3] c) Now compute the fraction: Fraction = (5.2 x 10-43 / 3.4 x 10-29 ) = 0.000000000000015 In other words, more than 99.99999999% of an atom is empty space !!!

  18. What’s in the Nucleus? Protons Neutrons Protons arepositively chargedand that amountof charge is exactlyequal (and opposite)to the charge of theelectron Neutrons are similar to protons (ie., similar mass), buthave a net charge ofzero. Recall: 1 [fm] = 10-15 [m]

  19. 1x 10-18 m (at most) • Protons 2 “up” quarks 1 “down” quark • Neutrons 1 “up” quark 2 “down” quarks (1.6 x 10-15 m) Are protons and neutrons fundamental? (By fundamental, I mean are they indivisible? The answer is NO ! Protons and neutrons are made of smaller objects called quarks!

  20. Three Families of Quarks Increasing mass Woohhh,fractionallychargedparticles? Also, each quark has a corresponding antiquark.The antiquarks have opposite charge to the quarks

  21. The 6 Quarks, when & where…

  22. How do we know any of this? • Recall that high energy particlesprovide a way to probe, or“see” matter at the very smallestsizes. (Recall Electron microscope example). • Today, high energy accelerators produce energetic beams which allow us to probe matter at its most fundamental level. • As we go to higher energy particlecollisions: 1) Wavelength probe is smaller  see finer detail2) Can produce more massive objects, via E=mc2

  23. Major High Energy Physics Labs Fermilab DESY SLAC KEK CERN CESR BNL

  24. Tevatron 1.25 miles Main Injector Fermilab Accelerator (30 miles from Chicago) Experimental areas Top Quarkdiscovered here at FNALin 1995.

  25. “Typical” Particle Detector

  26. Typical physicist colleagues! Don’t ask me what they’re doing !

  27. Summary • Protons and neutrons are made of up & down quarks. • The strange quark was uncovered in cosmic rays via their “strange”behavior. • Today, accelerators produce high energy beams of particles which illuminate the structure of matter.* Smaller deBroglie wavelength  finer microscope * Can produce massive particles which haven’t been around since the Big Bang! (E=mc2) • The charm, bottom and top quarks were all discovered by producingthem artificially at high energy accelerators.

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