/sci/ - Science & Math

>>11650721

So at least that far back in time, the Big Bang theory is right. We see some amazing clues in the image imprinted on the CMB. Firstly, it's incredibly smooth and even. But this mottled pattern shows there are imperfections, tiny differences in temperature of 1 part in 100,000 from one patch to the next. These represent regions where there's a bit more stuff here, a bit less stuff there. Very, very tiny fluctuations that would let it collapse on themselves to form galaxies and clusters of galaxies. That process, the evolution from a smattering of tiny fluctuations to a network of giant galaxy clusters, is also evidence that the Big Bang picture is right. When we look to vast distances, we're also looking back in time and we see the very first galaxies soon after they collapsed from these blobs. Now, we expect them to be violent places with galaxies colliding and merging with each other, rich in the raw materials of star formation but poor in the heavy elements released by generations of supernovae. And they are. We see galaxies back when the universe was 5% its current age. And they look very different to galaxies today. The universe is clearly evolving. But there's another amazing clue in the CMB. The pressure results in spherical sound waves of both baryons and photons moving with a speed slightly over half the speed of light outwards from the overdensity. We see ripples of "sound waves" in the pattern of those fluctuations. The fancy name is baryon acoustic oscillations which cause ring-like clustering of the CMB fluctuations. . If the Big Bang theory is right, then those ripples should have been frozen into the distribution of matter at the moment the CMB was created, and those ripples should still be visible in the way that galaxies are spread out on the sky. And yep. We see that, too.