The term Heat Death comes from the idea that, in an isolated system (the Universe being a very big example), the entropy will continuously increase until it reaches a maximum value. The moment that happens, heat in the system will be evenly distributed, allowing no room for usable energy (or heat) to exist – hence the term ‘heat death’. That means, mechanical motion within the system will no longer be possible.
This kind of ending is a stark contrast to what other scientists believe will be the Universe’s alternative ultimate fate, known as the Big Crunch. The Big Crunch, if it does happen, will be characterized by a collapse of unimaginably gargantuan proportions and will eventually culminate into an immensely massive black hole. The Big Freeze, on the other hand, will happen with less fanfare since everything will wind down to a cold silent halt.
To determine which ending is most possible, scientists need to gather data regarding the density, composition, and even the shape of the Universe.
For example, if the density is found to be lower than what is known as the critical density, then a continuous expansion will ensue. If the density is equal to the critical density, then the Universe will expand forever but at a decreasing rate. Finally, if the density is found to be greater than the critical density, the Universe will eventually stop expanding and then collapse.
It is therefore clear that, for a Big Freeze to occur, the density must be less than the critical density.
Accurate measurements made by the WMAP (Wilkinson Microwave Anisotropy Probe), which picks up cosmic microwave background radiation (CMBR), indicate a density that is much less than the critical density. This is very consistent with observations at the outer regions of the Universe; that being, increasing outward velocities of galaxies as they are further from us.
Through these observations as well as the density measurements, more scientists are inclined to believe that the most possible ending is that of a Big Freeze.
Articles on the big freeze are so hot. It’s a good thing we’ve got a nice collection of them here in Universe Today. Here are two of them:
- Dark Energy Could be a Breakdown of Einstein’s Theory
- No “Big Rip” in our Future: Chandra Provides Insights Into Dark Energy
Here are links from NASA about the big freeze:
Tired eyes? Let your ears help you learn for a change. Here are some episodes from Astronomy Cast that just might suit your taste:
- Multiple Big Bangs, Satellite Collisions and the Size of the Universe
- Ice in Space, Expansion of the Universe, and Death from the Skies