dirac’s idea - cheric · 2010. 6. 17. · dirac’s idea all negative energy states are already...
TRANSCRIPT
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Dirac’s ideaAll negative energy states are already filledBy the Pauli exclusion principle, no additional electrons can have negative energiesHole behaves like a particle with
positive energy (hole is a “lack of a negative energy electron”)positive charge (absence of a negative charge)
Anti-electron = positron (not proton)
Dirac sea
vast invisible “sea” of negative energy electrons
at least 2mc2
Pair creation Pair annihilation
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거울상 대칭 형태상호 작용력 차이 존재
Matter-antimatter
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Carl AndersonDiscovered in 1932 in cosmic rayNobel Prize in 1936
Proton hypothesis (Dirac) does not work2 particles must have identical massOppenheimer, Stückelberg, Feynman
they replace the E<0 particles with other (anti)particles of opposite charge
Discovery of positron
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Cosmic ray
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Every particle has an antiparticle1955: antiproton
Chamberlain-Segrè, Berkeley1956: antineutron
Cork et al., LBNL1965: antideuteron
Zichichi, CERN and Lederman, BNL
1995: antihydrogen atom CERN, by now millions produced
Some particles (e.g., the photon) are their own antiparticles !
반물질의 발견 역사
Anderson saw a track in acloud chamber left by“something positively charged,and with the same mass as anelectron”
lead plate
bubble chamber
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Antiproton 발견 (1955)
incoming antiproton
“annihilation star”(large energy release from antiproton destruction)
Reproduction of an antiproton annihilation star as seen in nuclear emulsion (source: O. Chamberlain, Nobel Lecture)
π
π
protons and α particles protons an
d α particles
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Antineutron 발견 (1956)
incoming antiproton
“annihilation star”(large energy release from antineutron destruction)
Antiproton charge-exchange reaction into neutron-antineutron pair in propane bubble chamber (source: E.G. Segrè, Nobel Lecture)
π
π
p + anti-p→ n + anti-n
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CERNCenter of European Organization for Nuclear Research
입자 가속기
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원자내 구조
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Electronme=0.92x10-30 kgqe=1.6x10-19 C=-qp
Protonmp=1.7x10-27 kgqp=qe=2x(2/3)-1x(1/3)
Neutronmn=1.7x10-27 kgqn=0=1x(2/3)-2x(1/3)
e, p, n의 전하량, 질량
e
p
n
ud
u
dd
u
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현재까지 발견된 원자의 구성 성분
Increasing Mass
전하
+2/3
-1/3
0
-1
u (up) c (charm) t (top)d (down) s (strange) b (bottom)e (electron) μ (muon) τ (tau)
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Family 별 질량 발견 역사
νe
e−
u
d
1e family 2e family
νμμ−
c
s
νττ−
t
b
3e family
(1 MeV ≈1.8∗10-30 kg)
m [MeV]
≈0
0.511
3
6
m [MeV]
≈0
106
1250
120
m [MeV]
≈0
1777
174300
4200
\© 1998
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1956
1897
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19631963
1937
1961 2000
178000
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1st family일정 형상을 지닌 모든 입자가여기에 속함
2nd, 3rd family빅뱅이후에 발생Cosmic ray나입자가속기에서만 관찰 가능
Leptons & Quarks
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Force particles
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아인슈타인의 첫번째 도전불확정성 원리 위배 사례
빛의 상자: 광자 하나의 에너지와 방출되는 시간을 정확히 결정할 수 있다!?
보어의 해석시간과 에너지는 불확정성 원리에 지배 받는다?!
Paradox 1: 빛의 상자
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아인슈타인의 두 번째 도전국지성에 관한 EPR 역설
Einstein-Podolsky-Rosen무한히 멀리 떨어져 있을 때, 한쪽 스핀의 방향이 결정되면다른쪽은 측정하지 않아도 자동으로 결정된다!
슈뢰딩거 고양이측정전까지는 상태를 알 수 없다
Paradox 2: 국지성