1. Entropy and the Arrow of Time
by: Nicholas Greika

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

3. 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

4. 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

5. 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

6. Notice anything?

7. 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"

8. 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?

9. 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
Monkeys at a typewriter
So then, what happened?

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

11. MinutePhysics on the Arrow of Time
YF30

12. Works Cited http://discovermagazine.com/2004/feb/cover/#.UTkCWVdIMVB
Did anything exist before the Big Bang?
Big Freeze article
Grand universe picture
Ted Talk, Sean Carroll-Cosmology and the Arrow of Time
MinutePhysics picture