all but 4 percent: dark matter and dark energy
DESCRIPTION
All but 4 percent: Dark Matter and Dark Energy. Our story begins in 1933…. The Coma Cluster of Galaxies and Astronomer Fritz Zwicky. Slow down – You move too fast!. The Coma Cluster of Galaxies and Astronomer Fritz Zwicky. Why don’t you fly apart?. - PowerPoint PPT PresentationTRANSCRIPT
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All but 4 percent:All but 4 percent:Dark Dark MatterMatter and Dark and Dark EnergyEnergy
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Our story begins in 1933…
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The Coma Cluster of Galaxies andAstronomer Fritz Zwicky
Slow down –You move too fast!
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The Coma Cluster of Galaxies andAstronomer Fritz Zwicky
Why don’tyou fly apart?
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The Coma Cluster of Galaxies andAstronomer Fritz Zwicky
If the Stars don’t weigh enough…
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The Coma Cluster of Galaxies andAstronomer Fritz Zwicky
Then something else does!
Dark Matter!
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40 years later, Vera Rubin shows galaxies spin too fast to hold together…
Stars and gas rotate with speed V around the center of NGC 3198(Image from Begeman 1989)
Measuring spectra of galaxies to infer velocity from Doppler shifts (c. 1970)
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…unless held together by dark matter!
Although diffuse, dark matter is crucial for galaxy formation
Credits:
Left: J. Kormendy (NGC 4216). Right: K. Begeman (NGC 3198) and K. Freeman
GM(r)=rVc2(r)
Darkmatter
Luminous galaxy
Embedded incloud of dark matter
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Recipe for our Universe!
Credit: NASA/GSFC
Photons: 0.03%Neutrinos: 0.3%Atoms: 4%Dark Matter: 23%Dark Energy: 73%
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4% does not gainadmissionto this show!
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What is the dark matter?
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What is the dark matter?
Not electrons, protons, or neutrons,
even if they do not “shine” as stars
(nuclear fusion in the early universe would drastically overproduce Helium)
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What is the dark matter?
Not known elementary
particles or combination
thereof
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Our best guess for the dark matter since 1977:
A new elementary particle
generically called a
Weakly Interacting Massive Particle,
or
WIMP
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How will we test this hypothesis?
Produce it in high-energy particle physics collisions
Simulated production of neutralino WIMP at a future International Linear Collider
(c. 2025)
Credit: Norman Graf, SLAC
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How will we test this hypothesis?
Watch it annihilate with anti-matter
NASA/DOE Fermi Gamma- Ray Space Telescope and other satellite and balloon experiments looking for this now!
Image credit: Sky & Telescope/ Gregg Dinderman
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How will we test this hypothesis?
When it hits us, we will know it (or will we?)
Many laboratory experiments are searching for atomic recoil from WIMP collisions.
Image credit: Discover/ Michael Attisha
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When a WIMP hits me, I’ll know it…
Cryogenic Dark Matter Search detector element in deep freeze (0.1 K), ½-mile underground in Soudan, MN
This experiment has not seen WIMPS yet, but has placed the best current limits on their properties if they exist.
See Technology Review May/June 2009!
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But wait, there’s more!
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A Strange Universe
Why are distant galaxies accelerating away from us?
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How to describe the expanding universe
Galaxies rushing apart on their own Stretching of space
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Imagine a repulsive force that grows
with distance between every pair of atoms
What would happen?
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Co-Discoverer of Cosmic Acceleration
Johns Hopkins ProfessorMacArthur Award Winner
Adam RiessMIT SB 1992
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A cancer has taken over the cellular machinery of space!
Linder 2008 Scholarpedia
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What is the cosmic carcinogen?
1. Einstein’s Cosmological Constant added to his theory of gravity – revoked, and…
…resurrected by modern physics as quantum fluctuations of the vacuum.
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What is the cosmic carcinogen?
2. Exotic new forms of energy, Dark Energy, behaving similarly to the quantum vacuum.
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What is the cosmic carcinogen?
3. Maybe Einstein’s theory of gravity is
wrong.
Phillip Zukin, physics graduate student
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What is the cosmic carcinogen?
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How can we find out?
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Study the growth of cosmic structure
after the big bang – gravity writes
history.