I had the honor to have lunch with Dr. John Mather today, who won a Nobel Prize in Physics for the discovery of the "seeds" of galaxy formation.
We know there are galaxies today, as stunning pictures from the Hubble Space Telescope reveal. What we do not know is what sparked the first tiny masses to start aggregating into the first galaxies.
Dr. Mather and collaborators made careful measurements of the temperature of deep space at colors too red for us humans to see, the sub-millimeter colors called microwaves. This radiation comes from space itself and not from stars or galaxies, so it is called 'background' radiation. This so called "cosmic microwave background" shines at a temperature of 2.73 degrees above the lowest possible temperature in the universe.
Interestingly, this 2.73 Kelvin temperature holds in all directions of space, assuming you first exclude the known stars and galaxies. What Dr. Mather added to this already remarkable story is to discover that while the temperature is always 2.73 Kelvin, there are small variations at the level of one part in 100,000.
This 'imperfection' in the 'thermostat' may seem like too small a difference to worry about, so that we can push it aside and still marvel at the fact that the whole universe radiates at 2.73 Kelvin. But, in addition to radiation in deep space there is also the mass of protons and dark matter which comprises the ingredients of our Milky Way.
These tiny changes in temperature allow also for tiny changes in the mass, and hence the formation of the first galaxies. So we may owe the existence of galaxies like the Milky Way, and even ourselves, to the imperfect thermostat of the cosmic microwave background radiation.
Now Dr. Mather leads the James Webb Space Telescope (JWST) project. The JWST is the successor to the Hubble Space Telescope with a launch date in October, 2018!