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Elementary Particle Physics. Microcosmos. The Wild W orld of Subatomic P articles The Story of the Higgs The Mystery of Dark Matter Particle P hysics and You!. Frank Linde Nikhef & UvA +31-205925001 f.linde@nikhef.nl. Dark ages. Long ago …. Empedocles. Air Water Fire Earth.
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Elementary Particle Physics Microcosmos • The Wild World of Subatomic Particles • The Story of the Higgs • The Mystery of Dark Matter • Particle Physics and You! Frank Linde Nikhef & UvA +31-205925001 f.linde@nikhef.nl
Long ago … Empedocles Air Water Fire Earth Plato Aristoteles Leucippus Democritus Atoms
Lead Gold 0 100 200 300 400 800 500 700 900 600 1900 1600 1700 1800 2000 1300 1400 1500 1200 1000 1100 Alchemy
NA atoms = 1 Mole 22.4 liters How large? 30-3001012 meters How heavy? 2-4501025 kilograms How many? 31023/gram hydrogen Number of atoms per volume independent of atom type! (Avogadro) gas Atoms NA = 6.0221420 1023/Mol
Periodic Table of Elements Het Periodiek Systeem nummering: kernlading Nobel gasses Not part of the original Mendeleev periodic table
Thomson 1897
e/m = 1.761011 C/kg Thomson 1897
qe = 1.60217646 1019 C me = 9.1093819 1031 kg Millikan 1900
1897 electron Thomson 1911 nucleus Rutherford 1911 proton Rutherford 1932 neutron Chadwick Elementary particles (1932): Electron, Proton & Neutron
Physics just before 1900 ??????? all ok ??????? • No: few “minor” problems: • “black body” radiation • no eather? • natural radioactivity (Curie et al.) • stability of the Rutherford atom Done?
I. Special relativity 1905
Intermezzo: Einstein & relativity Time travel becomes a reality!
2L c t = L ‘click’ of the light clock at rest: t ‘hence-and-forward’ light flash period t: c=299792458 m/s (exact) observer at rest
c=299792458 m/s (exact) v [m/s] L t’ == t 1v2/c2 2L c2v2 ½vt’ 2L2+(½vt’)2 c vt’ t’ = ‘hence-and-forward’ light flash period: t’ ‘click’ of the moving light clock: t’ (ct’)2 = 4L2+(vt’)2 t Moving clock ‘clicks’ slower! observer moving with velocity v
II. Quantum world 1900-19
Planck 1900 Einstein 1905 Compton 1922 Planck (1858-1947) Einstein (1879-1955) Compton (1892-1962) Light: quantum effects
I.Black body radiation Planck 1900
Stacking waves! Fit ½, 1, 1½, 2, etc. wavelengths in box such that amplitude=0 on walls L =2L =1L =½L Easier to fit short wavelengths!
Light wave's energy: classical E continuous! energy |amplitude|2
ultra-violet catastroph Radiated energy spectrum: classical energy density 0 m 0,5 m wavelength ()
Light wave's energy: quantum Planck’s constant h = 6.62606881034 J/s E = Nhf E discrete! energy E = 5hf E = 4hf # quanta N E = 3hf E = 2hf E = hf
ultra-violet catastroph Radiated energy spectrum: quantum energy density 0 m 0,5 m wavelength ()
Color the sun T=5,000 oC T=2,500 oC T=7,500 oC T=10,000 oC T=12,500 oC T=15,000 oC
Universe as black body radiator T 2.725 K 270.5 oC
knocked out electrons incident light wavelength (frequency f) slab of material II.Photo electric effect Einstein 1905
scattered light wavelength ’ incident light wavelength scattered electron III.Compton effect Compton 1922
Duality: wave & particle characteristics It is safe to say that nobody understands quantum mechanics. R.P. Feynman
Quantum mechanics is magic.Daniel Greenberger. Everything we call real is made of things that cannot be regarded as real.Niels Bohr. Those who are not shocked when they first come across quantum theory cannot possibly have understood it. Niels Bohr. If you are not confused by quantum mechanics, you do not understand it. John Wheeler. If quantum theory is correct, it signifies the end of physics as a science.Albert Einstein. I do not like quantum mechanics; I am sorry I ever had anything to do with it. Erwin Schrödinger. more quotes
Bohr 1910 Schrödinger 1927 Heisenberg 1925 Bohr (1885-1962) Schrödinger (1887-1961) Heisenberg (1901-1976) Atom: quantum effects
4 n = 5 3 2 1 n=3 n=2 n=1 Balmer serie Bohr’s atom model
0.0 Paschen 3 1.5 Balmer 2 3.4 quantum number (n) binding energy (eV) Lyman 1 13.6 eV
Heisenberg’s uncertainty principle /2 4 t large microscope microscope light t small t [s] t [s] light f large f small f [1/s] electron electron f [1/s]
Schrödinger’s wave equation n=1 1H ground state
n=1 n=2 n=3 “s” states
Uhlenbeck & Goudsmit 1925 Pauli 1925 Lorentz & Zeeman 1896 (1900-1958) (1887-1961) (1887-1961) (1901-1976) (1885-1962) Amsterdam Leiden Leiden Leiden Electron: quantum details
N N Z Z Stern Gerlach Zeeman
Electron spin! Uhlenbeck Goudsmit