a new paper published in Physical Review Letters gives a measure of neutrino mass, and it does so by alleviating the tension between cosmological parameters.
A Kodak Moment
NASA has recently released the WMAP 9 year mission results. It’s taken the WMAP team two years to analyze this latest (and last planned) round of data. On the one hand, the results are just as we expect.
Ripples on the Cosmic Pond
The amazing thing is that all these values fit in this single curve. If the values were different the peaks would shift left or right, or be higher or lower. While the image of the CMB is wonderful, with its swirls of color, this graph is even more wonderful. It tells us that our understanding of the universe is on track.
Relative Motion
There are actually two ways that the spectrum of microwave light can be affected. One is by changing the temperature of the source, but another is by moving relative to the source. The latter is commonly known as the Doppler effect. Just as the visible light from stars and galaxies can be shifted toward the blue when they are moving toward us and red when they are moving away from us, the CMB can be redshifted and blueshifted.
First Light
What’s truly amazing about this image is that it’s an observation of the first light of the universe. Within the first few minutes after the big bang, nuclei, electrons and photons formed, but for quite a while these were so hot that the light produced was quickly scattered or absorbed. Finally after about 380,000 years the electrons and nuclei formed atoms, and the light of the universe could finally travel freely through the universe.
Echo of the Big Bang
Evidence of an expanding universe doesn’t prove it began with a big bang. Claiming the observable universe was once smaller than an apple is a pretty crazy idea, so you’d be right to ask for more evidence before taking the idea seriously. Fortunately we happen to have a great deal of evidence. One of the earlier indications is known as the cosmic microwave background.