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Our Lopsided Universe:Our Lopsided Universe:The Matter with AntimatterThe Matter with Antimatter
Dr. Stephen J. SekulaLaboratory for Nuclear Science at theMassachusetts Institute of Technology
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This lecture is made possible by...
... You!
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Chapter 1Matter and Anti-Matter
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Matter and Anti-MatterMatter and Anti-MatterCourtesy of Alan Chou (SLAC)
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Einstein's Famous EquationEinstein's Famous Equation
E mc2
Energy and solid mass are equivalent Image © The Albert Einstein Archives, The Jewish
National & University Library, The Hebrew University of Jerusalem, Israel.
Albert Einstein taught us that:
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Paul Dirac: Paul Dirac: “Father of Anti-Matter”“Father of Anti-Matter”
The electron has a partner with opposite
electric charge but the same mass
(weight), and they cancel each other outThe existence of the electron (matter) begets
the existence of the positron (anti-matter)
Paraphrasing his 1933 Nobel Prize speech:
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From the Star Trek: The Next Generation Technical Manual
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The “Trek” of Anti-MatterThe “Trek” of Anti-Matter
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Anti-Matter and MedicineAnti-Matter and MedicineEver had a PET scan?
You've benefited from anti-matter!
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Locally Grown Anti-MatterLocally Grown Anti-MatterSLAC has produced a total of 0.0000002 pounds of positrons over the last 20 years.
Convert it all to energy over that time:33 Watts of power
That's not going to solve any energy issues...
...but it's more than enough to begin tacklingquestions about the origin and nature of the universe!
That's not going to solve any energy issues...
...but it's more than enough to begin tacklingquestions about the origin and nature of the universe!
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Photo courtesy of SLAC
SLAC 40-inch bubble chamber, 1971
12SLAC 40-inch bubble chamber, 1971
Photo courtesy of SLAC
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Dirac's Historical PerspectiveDirac's Historical Perspective“If we accept the view of complete symmetry between positive and negative electric charge so far as concerns the fundamental laws of Nature, we must regard it rather as an accident that the Earth (and presumably the whole Solar System), contains a preponderance of negative electrons and positive protons.”
“It is quite possible that for some of the stars it is the other way about... In fact, there may be half the stars of each kind.”
Paul A. M. Dirac, Nobel Laureate Speech, 1933
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Chapter 2The Big Mystery
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Looking Out, Looking BackLooking Out, Looking BackThe Big Dipper...
Many of these stars are 80 light-years away –- that's 480,000,000,000,000 miles!
Light travels at 186,000 miles per second, or 6 trillion miles per year!
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No Evidence of Anti-Matter...No Evidence of Anti-Matter...
No evidence of equal parts anti-matter and matter for many billions of light-years in any direction...
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The Mystery...The Mystery...
WHERE DID ALL THE ANTI-MATTER GO?
???
???
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The Last Echo of the Big BangThe Last Echo of the Big Bang
The Cosmic Microwave Background, a result of matter/anti-matter annihilation near the beginning of time.
Image taken by the Wilkinson Microwave Anisotropy Probe (WMAP)
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Courtesy of Alan Chou (SLAC)
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Chapter 3Journey to the
Beginning
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To try to solve this mystery, we have to go back to a time beyond the sight of our most powerful telescopes
-455°F
(Now)
5,400°F
Studying the universe at very high energy (high temperature) is equivalent to studying it when it was very young...
The Cosmic Time Machine
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““Little Bangs”Little Bangs”● If the Big Bang created the universe, what we
make at SLAC could be termed “little bangs”
● We currently recreate conditions at a temperature of 120,000,000,000,000 degrees Fahrenheit
That's 1 billionth of a second after
the Big Bang!
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Snapshots of the Beginning...Snapshots of the Beginning...
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Courtesy of Alan Chou (SLAC)
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Six “Bricks”: LeptonsSix “Bricks”: Leptons
Discovery of the Tau Lepton, 1995 Nobel Prize: Dr. Martin Perl (SLAC) and Dr. Frederick Reines (UC Irvine)
LEPTONSF
irst
Fam
ily Electron
Responsible for electricityand chemical reactions;it has a charge of -1
Electron Neutrino
Particle with no electriccharge and a vanishingly small mass; billion pass through your body every second
Sec
ond
Fam
ily Muon
A heavier relative of theelectron; it lives for two-millionths of a second
Muon Neutrino
Created along with muonsas a result of heavier particles decaying
Th
ird
Fam
ily Tau
Heavier still; it is extremelyunstable. It was discoveredin 1975.
Tau Neutrino
Discovered only very recently
Lay
out c
ourt
esy
of C
ER
N
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Six “Bricks”: QuarksSix “Bricks”: QuarksQUARKS
Fir
st F
am
ily Up
Protons contain two,Neutrons contain one
Down
Neutrons contain two,Protons contain one.
Sec
ond
Fam
ily Charm
A heavier relative ofthe Up; found in 1974
Strange
A heavier relative ofthe down; found in 1964
Th
ird
Fam
ily Top
The heaviest buildingblock. Discoveredin 1994
Bottom
The second heaviestbuilding block; discovered in 1977
Evidence for quarks: 1990 Nobel Prize to Dr. Jerome Friedman (MIT),Dr. Henry Kendall (MIT), and Dr. Richard Taylor (SLAC)
Charm quark discovery: 1976 Nobel Prize to Dr. Burton Richter (SLAC) and Dr. Samuel Ting (MIT)
Lay
out c
ourt
esy
of C
ER
N
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The CementThe CementGravityCarried by: unknownBinds anything with massGalaxies, orbits, weight.
Electro-magnetismCarried by: photonsBinds anything with electric chargeChemistry is a direct result
Gra
phic
cou
rtes
y of
CE
RN
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More CementMore CementThe Strong Nuclear ForceCarried by gluonsResults in the strength of the atomic nucleus
The Weak Nuclear ForceCarried by weak bosonsNuclear instabilityMerges with electro-magnetism to form a single force at high energy.
Gra
phic
cou
rtes
y of
CE
RN
Gra
phic
cou
rtes
y of
CE
RN
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Chapter 4Lopsidedness
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What is BaBar?What is BaBar?
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... A Particle Detector ...... A Particle Detector ...
... located at one of two “B Meson Factories” in the world (the other is KEK/Belle, in Tsukuba, Japan)... 31
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... A Collaboration ...... A Collaboration ...
...over 600 physicists from 75 institutions in 10 countries... 32
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... Part of the SLAC “B-Factory”... Part of the SLAC “B-Factory”
We produce “B” mesons and their anti-matter counter-parts,
written “B”. “B and B-bar = BaBar”
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What is a What is a MesonMeson??A Meson is a pair of quarks, bound by the Strong Force
b
d
A “B0” Meson
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Looking for LopsidednessLooking for Lopsidedness
B0 Meson
positron
electron
anti-B0 Meson
50% Matter50% Anti-Matter
Is it still 50% Is it still 50% matter and 50% matter and 50% anti-matter???anti-matter???
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Lopsidedness Revealed!Lopsidedness Revealed!
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Enough Lopsidedness?Enough Lopsidedness?Galileo Galilei used the telescope as an instrument to understand the universe...
The Standard
Model
Particle physicists use a mathematical tool called “The Standard Model” to do the same...
The Standard Model is the single most successful theory of nature ever developed...... but it is not enough...
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Great Challenges to PhysicsGreat Challenges to Physics● Matter/Anti-Matter asymmetry falls outside
the Standard Model
● Recent experimentsshow just howlittle we knowand how muchwe don't knowabout ouruniverse
Our Universe
The domain of the Standard Model
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The Quest Continues!The Quest Continues!● Our lopsided universe is a result, not an
accident...– It is testably lopsided! We can see it happen!
– A result of what? What are we missing?
● To understand why, we have to connect the miniscule and the cosmic!
● Physicists at SLAC and across the globe are challenging these and many other questions head-on!
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More SLAC Public Lectures!More SLAC Public Lectures!● “Metals, Molecules, Life, and Death”
– Graham George (August 31, 2004)
– Metals are a boon and a bane to living organisms. Learn about their role in life, and how the Stanford Synchrotron Radiation Laboratory (SSRL) reveals the story!
● Particle Astrophysics– Roger Blandford (October 26, 2004)
– Learn about the connections between the minute and the cosmic, and how SLAC is trying to shed light on the “missing” 95% of our universe!
http://www.slac.stanford.edu/lectures
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Please join us for refreshments in the
lobby!
Physicists are here tonight to chat with you!
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