Anything lower than -100 F calls for at least 5 layers.
SPT and BICEP.
The Cosmic Microwave Background (CMB) consists of photons at very low energy levels (T.A. = 10^-5) and is a relatively homogeneous remnant from the big bang, meaning that throughout the universe CMB temperatures are constant. Deviations from the baseline temperature indicate either excitement or downgrades in energy. Since, CMB is of a low energy it's wavelength is of the microwave spectrum, i.e., 95 GHz. If a CMB photon passes through a galaxy cluster, the most massive entities known to exist in the universe, electrons from the cluster may excite the photon and increase it's energy, thus temperature. This energy increase pushes the photon outside the selected microwave spectrum viewed by the South Pole Telescope and indicates a point source on a map of where a galaxy cluster is. In order to view the microwave spectrum of the universe SPT needs to be cooled to almost absolute zero. Some 40 scientists and engineers from various universities have successfully worked together and created a system that cools the microwave sensors down to -0.27 K using H3. At that temperature the sensors operate in a near superconducting state. Within the sensor chamber the few molecules that can exist at such low temperature are helium.
What the SPT's CMB detection tells us is where galaxy clusters are and what the universe looks like. The two key theories that are predecessors to any further SPT inquiries are: (1) the universe is expanding and (2) it's expansion is of a linear fashion. The Cosmic Microwave Background is the result of the universe's expansion; energy from the big bang traveled so far that it cooled down to the very reaches of the microwave spectrum. Slow, cold moving photons. Furthermore, if these CMB photons get excited while in a galaxy cluster they transport energy elsewhere in the universe. The photons do not adhere to gravity, even if excited, they simple pass on though a cluster. This to me is a sign that yes, the universe is expanding, but it is also cooling. Think about our own solar system. For a billion or so years the sun will get more luminious and hot, but eventually it will use up all it's nuclear fuel, expand, and cool to a red giant (in ~5 billion years). Earth will be toast.
Expansion and cooling is what current physics tells us is going on. But, I beg the question, cannot dark matter outweigh dark energy and reverse the cycle and produce universal contraction? Big Bang #2? Dark energy is the energy behind the universes expansion and dark matter is very heavy material with so much gravity that it holds galaxies in place. Galactic and stellar matter is inside dark matter. If there was no dark matter than spiral galaxies and galaxies alike would just spiral away into the depths of the universe where they would cool and decay into the most basic elements of energy; photons.