According to Professor Cox, although we may think that we're evolving and progressing, the universe is moving steadily from its creation to its demise because of the Second Law of Thermodynamics. Cosmologists like Professor Cox believe in an hypothesis known as 'heat death'. This states that everything in the universe is moving towards becoming a uniform temperature, at which point there will be no more stars, no more black holes. No more anything, pretty much.
So What Is the Second Law of Thermodynamics?
The Second Law of Thermodynamics, which is also known as the Law of Entropy, was initially formulated in the nineteenth century by scientists and engineers who were working on the development of more efficient steam engines. The Law states that our world, when left to itself, always behaves in such a way as to increase entropy. The term entropy has specialised meanings in the context of thermodynamics and cosmology, but it can be defined basically as the tendency of everything to move from order to decay. If you put a glass of hot water in a cold room, the heat flows out of the water - in other words, the heat 'decays' - into the air of the room until they are both at the same temperature, at which point the flow stops. This is the point of maximum entropy. In the same way, the heat of our sun and the other stars is flowing outwards until a state of uniform temperature is reached. We are billions of years away from this, but, according to the Second Law of Thermodynamics, it is inexorable.
Professor Cox uses a sandcastle to demonstrate the Second Law of Thermodynamics. A sandcastle is a highly-ordered structure; that is to say, it is in a state of low entropy. However, once it has been built and if it isn't maintained, it inevitably crumbles back into a pile of sand. All the physical laws of the world act upon it to return it to maximum entropy. Entropy is the natural condition of everything.
The Arrow of Time
This universal law, that our world always behaves to increase entropy, is used to explain the Arrow of Time. The Arrow of Time says that time always moves in one direction, from the past to the future. And it always moves in this direction because of the Second Law of Thermodynamics. The sandcastle is unable to spontaneously rebuild itself, even though its constituent grains of sand are still there.
I am certainly no physicist, and Professor Cox explains his concepts in a way that is both illuminating and entertaining. But I walked away from my television with a great many unanswered questions. How does the Big Bang fit into the Second Law of Thermal Dynamics? If everything moves inexorably from order to decay, what created the order in the first place? How? Did the Second Law not exist at that point? Is Professor Cox's explanation no more than a theory, an hypothesis, and, if so, what are the alternatives?
I am looking forward to seeing if he answers any or all of these questions in following episodes. In the meantime, I shall continue my own investigations into what other cosmologists are thinking. However, if his intention was to generate enthusiastic inquiry into his subject, he has most definitely succeeded.
Sources
Cox, Brian The Wonders of the Universe Part 1 'Destiny' BBC March 2011
N. J. Evans - N.J. Evans lives in North Yorkshire, England and works as a freelance writer and novelist. She has a Masters Degree in Medieval Studies ...
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