The Most Misunderstood Concept in Physics

17:08

Ultimately, all the energy that reaches earth from the sun is converted into thermal energy, and then it's radiated back into space. But in fact, it's the same amount.

19:37

So right after the Big Bang, that is when the entropy was lowest

19:51

But the early universe was hot, dense, and almost completely uniform, everything was mixed and the temperature was basically the same everywhere, varying by at most 0.001%. So how is this low entropy?

20:15

Taking gravity into account, having matter all spread out like this, would be an extremely unlikely state, and that is why it's low entropy

21:09

The universe started with around 10 to the 88 Boltzmann constants worth of entropy

21:15

All the stars in the observable universe have about 9.5 times 10 to the 80

21:20

The interstellar and intergalactic medium combined have almost 10 times more

21:29

A lot more is contained in neutrinos and in photons of the cosmic microwave background

21:36

In 1972, Jacob Bekenstein proposed another source of entropy, black holes

22:49

The super massive black hole at the center of the Milky Way has about 10 to the 91 Boltzmann constants of entropy

23:06

All black holes together account for 3 times 10 to the 104 Boltzmann constants worth of entropy

23:14

Almost all the entropy of the universe is tied up in black holes

23:19

The early universe only had about 0.000000000000003% of the entropy it has now

25:26

Both low and high entropy are low in complexity. It's in the middle where complex structures appear and thrive