“Silently, one by one, in the infinite meadows of heaven,
Blossomed the lovely stars, the forget-me-nots of the angels.” –Longfellow
The cosmic microwave background is a thing of beauty, as not only does its uniform, cold temperature reveal a hot, dense past that began with the hot Big Bang, but its fluctuations reveal a pattern of overdensities and underdensities in the very early stages of the Universe.
It’s fluctuations just like these that give rise to the stars, galaxies, groups and clusters that exist today, as well as the voids in the vast cosmic web. But effects at the surface of last scattering are not the only ones that affect the CMB’s temperature; if we want to make sure we’ve got an accurate map of what the Universe was born with, we have to take everything into account, including the effects of matter as it gravitationally grows and shrinks.
As we do exactly this, we find ourselves discovering the causes behind the biggest anomalies in the sky, and it turns out that the standard cosmological model can explain it all. Find out what it all means on this week’s Ask Ethan!