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NASA Reports on First WMAP Cosmological Results


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The Wilkinson Microwave Anisotropy Probe, launched in June 2001 at a cost of $145 million, looked back to the very beginning of the universe by looking at the cosmic microwave background radiation, the energy which keeps the temperature of a vacuum at 2.725K, just above absolute zero. Temperature changes in the CMB were mapped within 35 millionths of a degree, making the pictures 35 times sharper than COBE, MAP's predecessor. The new findings were measured using very different frequencies: K-Band, Ka-Band, Q-Band, V-Band, and W-Band.

Age of the Universe

The first frame of the picture on the left of of the cosmic microwave background radiation just 379,000 years after the Big Bang, over 13.7 billion years ago-- the estimated age of the universe, within 0.2 billion years.

The Hubble Constant

The measured value of the Hubble constant was 71 +4/-3 km/s/Mpc, the most accurate measure ever. This means that the geometry of the universe is flat with adiabatic Gaussian fluctuations on a scale-invariant spectrum.

Decoupling and Reionization

The age of decoupling was also determined to be 379 +8/-7 thousand years, at a redshift of 1089 +/- 1. The age of decoupling refers to when the universe became transparent.

This was the most accurate determination of the age of reionization to date. The determined value is 180 million years. This epoch was when the opaqueness of the universe was broken by the cooling matter being split from hydrogen to a proton and an electron.

Matter Condensation

Frame 2 shows areas of higher density pulling in matter from areas of lower density, which led to matter condensation. The WMAP indicated that the matter created during the big bang condensed approximately 200 million years after the big bang; much earlier than previously estimated. (Frame 3). Frames 4 and 5 show the formation of stars and galaxies from this condensation.

Above: Detailed image of the CMB, combined from all bands.

Composition and Fate of the Universe

The question of dark matter and dark energy has also been answered. The WMAP indicated that the universe has the following composition: dark energy 73%, dark matter 23%, atoms 4%. That 4% makes up all the stars and planets, and us. The dark energy is the force that overcomes gravity to keep the universe expanding. The 73% density of dark energy means that the universe will keep expanding forever, eventually resulting in a heat death. "Not with a bang, but with a whimper"

The data about dark energy provides some vindication for what Einstein called the greatest blunder of his career- the cosmological constant. It now appears as though the dark energy is what the cosmological constant referred to, although quintessence is another possible role of it.

Neutrinos, though present, did not significantly interact with matter as to influence the early development of matter.

 

Technical papers: http://map.gsfc.nasa.gov/m_mm/pub_papers/firstyear.html

 

WMAP mission results home page:

http://map.gsfc.nasa.gov/m_mm.html

 

 

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