all but 4 percent: dark matter and dark energy

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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.