Wilkinson Microwave Anisotropy Probe

(WMAP)

By Susan Creager

April 20, 2006

Two theoretical principles of the Big Bang

• General Relativity

• The Cosmological Principal

General Relativity

• Gravity is not a field, but a distortion of space and time. This applies to bodies at motion as well as at rest. Its speed is the speed of light.

The Cosmological Principle

• Matter is distributed evenly when averaged over large areas.

Three theories of the shape of the universeThree theories of the shape of the universe

Observational Tests of the Big Bang

• Expansion of the Universe

• Abundance of the light elements H, He, Li

• The Cosmic Microwave Background Radiation

Cosmic Background Radiation – the radiant heat left over from the Big Bang. It formed a few thousand years after the Big Bang before

stars and galaxies.

Why Study CMBR?

Visible Stars

• 10-100 years ago

Andromeda Galaxy

• 2.5 million years ago

Hubble Telescope

• A few billion years ago

What is in the universe?

• Radiation – massless or nearly massless particles that travel at the speed of light. These include photons and neutrinos.

• Baryonic matter – protons, neutrons, and electrons• Dark matter – not observed, but suspected• Dark energy – the only form of matter that can cause the

universe to speed up

Composition of the UniverseComposition of the Universe

Wilkinson Microwave Anisotropy Probe (WMAP)

3.8 x 5 meters

840 Kg

Its purpose is to map the temperature fluctuations of the CMBR.

WMAP – launched in June 2001

Launched in 2001, it was originally meant to be a 27 month mission. NASA later extended its time frame.

Original Logo – Wilkinson was added preceding MAP to honor Dr. David Wilkinson, a member of the team and a pioneer in cosmic background

radiation.

Anisotropy

• Fluctuations in cosmic background radiation. CMBR is very cold – only 2.725 degrees above absolute zero.

• Fluctuations may range very slightly from 2.7251 and 2.7249 degrees in one portion of the sky.

• Red areas are warmer• Blue areas are cooler

• White lines show “polarization” direction of old light

Early cosmic background radiation

Material is gravitationally pulling together

Stars are forming

Galaxies are forming

The present sky

References

• http://map.gsfc.nasa.gov/

• http://en.wikipedia.org/wiki/Wilkinson_Microwave_Anisotropy_Probe

• http://www.daviddarling.info/encyclopedia/M/Microwave_Anisotropy_Probe.html