He said, well, entropy increases because there are many, many more ways for the universe to be high entropy, rather than low entropy.

The reason why entropy increases is simply because there are many more ways to be high entropy than to be low entropy.

So it's not that entropy must always increase you can get fluctuations into lower entropy, more organized situations.

That's the region where entropy is low.

Boltzmann explained that if you start with low entropy, it's very natural for it to increase because there's more ways to be high entropy.

So we know that positive entropy is something good for spontaneity.

Here's a graph that plots the entropies of a whole bunch of sequences.

What he didn't explain was why the entropy was ever low in the first place.

So he says I'm not going to do the accent he says, For some reason, the universe, at one time, had a very low entropy for its energy content, and since then the entropy has increased.

An egg, an unbroken egg, is a low entropy configuration, and yet, when we open our refrigerator, we do not go, Hah, how surprising to find this low entropy configuration in our refrigerator.

If the universe is not a fluctuation, why did the early universe have a low entropy?

Let's think of the situation where our delta H is less than 0, and our entropy is greater than 0.

This insight that entropy increases, by the way, is what's behind what we call the arrow of time, the difference between the past and the future.

SSL entropy file

A high entropy arrangement is one that there are many arrangements that look that way.

The fact that you are born, and then you live, and then you die, always in that order, that's because entropy is increasing.

The fact that the entropy of the universe was low was a reflection of the fact that the early universe was very, very smooth.

Use entropy file

Path to entropy file

Waiting for entropy

But let's say I lose entropy.

And we already had the sense that look, if this is negative and this is positive, we're getting more entropic and we're releasing energy, that should definitely be spontaneous.

You've heard of entropy.

But let's say I lose entropy.

A low entropy configuration is one in which there's only a few arrangements that look that way.

When temperature is high, this less entropic state, they ram into each other, and they'll become more entropic.

We have delta S, our change in entropy.

Maybe there is something that naturally, through the growth of the laws of physics, gives rise to universe like ours in low entropy configurations.

SSL egd socket

In this situation, entropy was negative.

So positive entropy should make my whole expression more negative, so maybe we should subtract entropy.

We have more disorder, more entropy.

So it seems like entropy matters somewhat.

In every one of these books, every one of these sets of lectures, he emphasized this puzzle Why did the early universe have such a small entropy?

We've seen that entropy is related to the number of particles we have.

When temperature is high, entropy matters a lot.

When temperature is low, entropy doesn't matter.

This is a situation where we're going to be more entropic after the reaction.

So when temperature is high, entropy matters.

Such a random jumble of letters is said to have a very high entropy.

So what if we just scaled entropy by temperature?

Information, too, can be measured and compared using a measurement called 'entropy.'

Every difference that there is between the past and the future is because entropy is increasing the fact that you can remember the past, but not the future.

But if you're Boltzmann, you know that if you wait long enough, the random fluctuations of those molecules will occasionally bring them into lower entropy configurations.

But what if our delta S, what if our entropy goes down?