Wednesday, 30 October 2013

The Heat Death of the Universe and Other Horrible Topics for Light Dinner Conversation

We have had a bit of a rough ride this month, learning about the dangers of space. From stars expanding to comet and asteroids crushing us from above we have seen that there is no shortage of potential assassins in this Universe of ours. But what if the Universe itself were to put an end to life? And not just life on Earth, life everywhere. It is not only possible; research has shown that it is downright probable.

To understand what it is about the Universe that all but guarantees an end to life as we and everything else knows it we have to take a physics lesson from a half-crazy, reclusive nut job genius named Isaac Newton. Most people know Newton from the story of him getting beaned with and apple and conceiving gravity as an idea. Most people don’t know that he also devoted a good portion of his life to things like trying to turn mercury into gold and sticking needles between his eyeball and eye socket to see what would happen. But as crazy as he may have been, he was equally brilliant. Beyond gravity, he bestowed upon science the 4 truths about the universe known as the Laws of Thermodynamics.

The fours laws are an article in themselves so I will leave a thorough explanation for another day. What concerns us now is the concept we get from them that is called entropy. Entropy is disorganization. It is the idea that as time goes on the elements of a system that are able to do work get used up and productivity declines. A favourite way to think of it is in terms of a game of billiards (read Bill Bryson's A Short History of Nearly Everything). At the start of the game, the balls are all very close together (low entropy) so it is easy for them to bash into each other and exchange energy. That is why when you break at the start of the game the balls all fly off in every which direction. As the game goes on entropy increases as the organization decreases, eventually leading to a state where you have to plan and target shots over a greater distance to get any work done at all (high entropy).

The Universe is a little bit like that game of billiards. In the beginning, everything was tightly packed together. In fact, all matter was a single point of immense potential energy. The Big Bang is the result of that potential energy and the equivalent of the break at the start of the game. The problem with the Universe is that there aren’t any edges to the table so things can expand forever and the interaction between particles will eventually become non-existent. This is known as The Heat Death of the Universe.

It’s not the cheeriest idea in astronomy but it has been around for a while. Einstein first saw the potential for infinite expansion when he established his Theory of Relativity. He hated the thought so much that be tacked on an extra term to one of this most important equations that fudged the math just enough to reassure him that gravity would eventually stop the expansion and hold everything together. He called it the Cosmological Constant.

Eventually as more evidence came in from work done by Edwin Hubble (who later had a space telescope named in his honour) suggesting that the Universe was expanding at an increasing rate, Einstein came to regret his constant and the wishful thinking it embodied. Modern scientist, however, are re-warming to its use as an explanation for the increasing speed at which the Universe is being flung apart.

The Cosmological Constant is being repurposed to account for the bizarre energy that seems to exist to counteract gravity and push things further and further away from one another. The eventual outcome (don’t worry, this is eons in the future) will be total heat death. The Universe will be an evenly distributed cloud of protons. Cold and impotent in the vastness of space… I guess we better enjoy our cosmic game of billiards while things are still energetic enough to allow it.