0:00 Think about a brand-new deck of fifty-two cards, sealed in the box, perfectly ordered by suit and number.0:07 Yes!0:08 Ace, King, Queen, Jack, all the way down.0:11 Perfect order.0:12 Now, what happens the very first time you shuffle them?0:16 Chaos.0:16 You get a random mess.0:18 And you're never, ever going to shuffle them back into that perfect order by accident.0:25 It feels like the exact opposite of our talk on DNA in episode eight, where nature builds these incredible, highly-ordered data storage systems.0:35 It is the exact opposite!0:37 And the rule that governs that shuffle is one of the most fundamental laws of the entire universe.0:45 It's called entropy.0:46 I've heard that word thrown around a lot.0:49 It sounds complicated and...0:51 physics-y.0:52 What does it actually mean?0:54 It's actually just a way of counting.0:57 That's it!0:58 Entropy is a measure of how many ways you can arrange something.1:02 Think about your bedroom.1:04 How many ways can it be perfectly clean?1:07 Uh...1:08 one way.1:08 The way my mom wanted it.1:10 Everything in its exact place.1:12 Exactly!1:13 Low entropy.1:14 Now, how many ways can your room be messy?1:17 Infinite ways.1:18 Clothes on the floor, clothes on the chair, books on the bed...1:23 A bajillion ways!1:24 That's high entropy.1:26 The universe just naturally drifts toward states that have more options.1:31 It's not magic, it's just probability.1:34 There are vastly more ways to be messy than to be neat.1:38 The universe is lazy!1:39 It likes having options.1:41 Okay, so a dropped glass shattering on the floor.1:45 It goes from one single, ordered glass to a thousand disordered pieces.1:50 That’s entropy increasing.1:52 You got it!1:53 Or ice melting.1:54 You have a solid, ordered crystal lattice—that's the ice cube.1:59 Then it melts into a puddle of water, where the molecules are all jumbled up and moving freely.2:06 The system moved from a low-entropy state to a high-entropy state.2:11 This is the big one, the Second Law of Thermodynamics.2:15 And that law says...?2:17 It says that in a closed system, the total amount of entropy—the total amount of disorder—can never decrease.2:25 It can stay the same, but it almost always goes up.2:29 The universe is a one-way street toward more and more disorder.2:33 Hold on.2:34 What about me?2:35 I'm a person.2:36 I'm an incredibly ordered collection of cells and systems.2:40 A tree is an ordered system.2:42 Doesn't life itself violate the Second Law?2:46 Ah, that is the best question!2:48 But you are not a closed system.2:50 To keep your body ordered, you have to eat food, right?2:54 Right.2:55 You take a highly-ordered piece of food, like an apple, and your body breaks it down, creating a huge amount of disordered waste heat and simple molecules.3:06 You are an entropy machine!3:09 You create a massive amount of disorder in the universe around you just to maintain your own little pocket of order.3:17 So I’m making the universe messier just by being alive.3:21 That's...3:22 a weird thought.3:23 It's true for the sun, too!3:25 A star is an incredibly ordered, dense ball of gas.3:29 But to maintain that order, it pours a tidal wave of heat and light—disordered energy—out into the void, massively increasing the total entropy of the universe.3:41 So if this one-way street of disorder is the rule for everything...3:46 where does the street end?3:48 What's the final destination?3:50 It's a concept called the 'Heat Death of the Universe.' It's the logical conclusion.3:57 Eventually, all the stars will burn out.4:00 All the energy will have spread out evenly.4:03 Everything, everywhere, will be the exact same, lukewarm temperature.4:08 So no hot, no cold.4:09 No movement.4:10 No anything.4:11 A state of perfect, maximum entropy.4:14 The energy is all still there, but because there are no differences, no gradients, no work can be done.4:22 Nothing can happen.4:23 Ever again.4:24 It's just a thin, quiet, unchanging soup.4:27 Wow.4:27 So all the beautiful complexity we see—stars, galaxies, life—it's all just a temporary side effect of the universe systematically falling apart.4:38 Exactly.4:39 We are just a beautiful, intricate splash in a river that only, and always, flows downhill.
