Why are the conditions in Antarctica ideal for looking at the cosmic microwave background?
The CMB is made up of photons from the primeval oven that the universe forged the first elements in. These are the lightest elements, and when they were formed the leftover binding energy of formation was released as a form of heat. That heat propagated throughout the universe for 13.8 billion years until it arrived at our telescopes.
My community has built satellites that have been to space to study the CMB, and that’s done at great expense and great risk. It’s almost 100 times more expensive if we wanted to put BICEP2 [Background Imaging of Cosmic Extragalactic Polarization] in space than the way we built it at the South Pole.
Microwaves are efficient absorbers of water, and water is very much present in Earth’s atmosphere. The atmosphere above the South Pole is very space-like – it’s very desert-like. There are very few water molecules in the atmosphere. We don’t want these photons that are so precious to us, and so few, travelling across the universe, and all of a sudden they smash into a water molecule in our atmosphere. That’s no good. All of our microwave telescopes need to be built at high
elevation, in very cold climates or both.