TitelThe Oldest Memory:

The Echo of the Big Bang

What is the oldest memory?

•First question: What is the start of time?

•Creation of the universe – The Big Bang!

•Is there any „memory“ of this event?

1965: Penzias & Wilson

Blackbody radiation

Cosmic Microwave Background

2,725 ± 0.002 K

What is the CMB?•Universe is expanding (Hubble flow)- Doppler Effect:

•Expanding blackbody: Still a blackbody, but cooler

•CMB: The cooled down blackbody named Universe

Universe started in a hot, dense state

CMB is „The Echo“ of this Big Bang

(This was already predicted by Gamov in the 40‘s)

Static source Moving source

Measuring the Anisotropy

WMAP: The „raw“ data

Subtracting the Doppler Dipole

Substracting the Galaxy

What to learn from the CMB?

•Anisotropies are caused by slight inhomogenities

•Inhomogenities interact with sound speed

•Cosmic expansion decouples light from matter CMB shows „last scattering surface“

•Results in length scale allows to measure the geometry of the universe

•Geometry related to fundamental parameters

Results: Power Spectrum

The Universe is flat!

Fundamental Parameters

Relative Abundance:

•„Usual“ (Baryonic) Matter: 4.4% ± 0.4%

•Total Matter: 27.0% ± 4.0%

•Dark Energy: 73.0% ± 4.0%

We only know about ~5% of our universe!

So... Plenty of work to do!

For more information: http://map.gsfc.nasa.gov/