Entropy and the Arrow of Time by: Nicholas Greika

Questions Why can we remember the past, but not the future? Is space finite? What would happen when a thermal equilibrium is reached?

Entropy Defined as disorder within a system Formulated by the 2nd law of thermodynamics As time approaches infinity, entropy also approaches infinity In the past, the universe was hotter (more condensed) Boltzmann's formula from determining how many ways a system could be arranged Based on the logic that it is much easier to have high entropy than low entropy S = k logW

Arrow of Time Entropy is increasing Universe is expanding As humans, we begin from low entropy (disorder), and over our lives come to a higher entropy Why did the universe start at a low entropy? Universe is expanding In a 1998 discovery, cosmologists found that the universe was (and is), contrary to popular belief, expanding. Galaxies are constantly accelerating away from each other, which is caused by dark energy that "pushes" them away

The Universe is Expanding Is space finite? The answer is no. When we establish that time is infinite, and that the universe will expand infinitesimally, then space must also be infinite We as humans can only see to a certain point, much like a horizon, that we call the observable universe Which has a circumference of 93 billion light years

Notice anything?

Wait, but what about heat? As the universe expands, heat must expand with it, in an attempt to reach a thermal equilibrium Boltzmann proposed that we could not live in a universe in which a thermal equilibrium had been met Big Freeze theory Fortunately, because space is ever-expanding, that thermal equilibrium will never be met In empty space, dark energy produces radiation that causes thermal fluctuations This drew the conclusion that the universe was like "an eternal box of gas"

If we were locked in a room literally forever... Back to Boltzmann If we were locked in a room literally forever... The universe, as an eternal box of gas, must have started with a high entropy, then became low entropy due to fluctuations, then again became high entropy In the universe, large thermal fluctuations may create planets, stars, or even entire other universes Would this imply that our planet may only be the result of a fluctuation, one in which life is possible? Would this also imply the existence of a multiverse?

Why is Boltzmann’s theory incorrect? "From the hypothesis that the world is a fluctuation, all of the predictions are that if we look at a part of the world we have never seen before, we will find it mixed up, and not like the piece we just looked at. If our order were due to a fluctuation, we would not expect order anywhere but where we have just noticed it. We therefore conclude that the universe is not a fluctuation. Richard Feynman, "Feynman Lectures on Physics", Volume I, p. 46-48 Monkeys at a typewriter So then, what happened?

Eggs and Such Call to mind an egg... The concept of the universal chicken So, which came first?

MinutePhysics on the Arrow of Time http://www.youtube.com/watch?v=GdTMuiv YF30

Works Cited http://discovermagazine.com/2004/feb/cover/#.UTkCWVdIMVB Did anything exist before the Big Bang? http://www.universetoday.com/36917/big-freeze/ Big Freeze article http://tribesorcreation.files.wordpress.com/2010/03/grand_universe_by_antifan_real1.jpg Grand universe picture http://www.youtube.com/watch?v=WMaTyg8wR4Y Ted Talk, Sean Carroll-Cosmology and the Arrow of Time www.youtube.com/watch?v=v6o2bUPdxV0 MinutePhysics picture