Things You Thought You Knew – Rocks Float

24:34Neil deGrasse Tyson:We good. That's like aliens with ray guns, and you're up there with a pistol shooting at it. It's like, no, can you just see the situation here? I am so glad you said that because I hate when they do that. In the movies. In the movies. When the earthlings go up against the aliens, and the earthlings are shooting bullets, and the aliens are shooting laser beams. Laser beams that vaporize their homes, right? And I'm like, really? Come on. And we win? Come on. Come on. All right. Bought a pistol to a laser fight. Get out. All right. Back to rocks. Rocks are dense or not dense? No, they're light. They're light.

25:14Neil deGrasse Tyson:Now, here's why. Earth was once molten. Okay. In the early days of formation. When you're molten and you're as big as the Earth, gravity will do things to that molten mixture. Okay? All right. That makes sense, right? Okay. So if you're denser, if you're heavier, if you're denser, you will sink to the middle. Right. That makes sense. If you're lighter, you'll float. This happens with any, if you're mixing oil and vinegar for your salad. Okay. You're mixing anything. Layer cocktails. For example. And generally, well, always, the lower density stuff will float on top of the higher density stuff.

25:53Neil deGrasse Tyson:Some things you can mix and it'll stay mixed for a while. That's cool. But that's how things work. Okay. So why is it that when you walk around Earth's surface, you find rocks? Okay. Earth does not have rocks in its core. You know what it has in its core? Iron. Iron. Nickel. Right. Magnesium. Right. Okay? It's got heavy metals in its core. because all the heavy stuff sank to the middle and all the light stuff floated to the top. So Earth's crust, where the active ingredient is rock, is the lightest stuff in Earth when it formed. So the, oh my God. Sorry, sorry, sorry. It's the third lightest. It's the third lightest.

26:50Neil deGrasse Tyson:Third lightest. The very lightest stuff are the gases, okay? Okay, yeah. So they're floating over your head. Right, okay. Okay? And next is the water. Okay. All right. Okay? So the water sank to the bottom of the gas. Makes sense. Okay. That's Earth's surface. There you go. And what sinks to the bottom of the water? Rocks. Rocks. And what sinks below the rocks? All the rest of the crap that Earth is made of that's heavier than the rocks. So rocks are the third lightest thing that came about in the creation of the Earth. Yes. Basically. Basically. And it's made our crust. Now, everything didn't solidify in the same instant.

27:25Okay.

27:26Neil deGrasse Tyson:And plus you have volcanoes that communicate lower layers with upper layers and things. So there is some of this, but that's why if you're looking for iron, you got to find the iron ore. Okay. The iron ore what? You know exactly what I'm saying. I'm sorry. I had to do it. I had to do it. It was so bad, but I couldn't resist it. It was so bad. It was good. Okay. I know. It was so bad it was good. Okay. So there's iron ore, nickel ore. So it's not everywhere. There are these places where these veins had been preserved at the point Earth was solidifying. Okay? So you get this remnants of the stuff.

28:08Neil deGrasse Tyson:You want to find out where most of the iron is and most of the nickel is on Earth? It is in the center of the Earth. And the universe has a lot of nickel and iron in it. Right. So Earth got its plenty of its share of those two ingredients, and it's in our core. And you might say, well, how do you know you've never been there? Let me hear it. Well, how do you know you've never been there? I like that accent. That was the obnoxious kid in the classroom. How do you know, Mr. Astrophysicist? You've never been there. So we have geophysicists who, anytime there's an earthquake, they can time the passage of the earthquake signals through the different layers of the Earth.

28:51Neil deGrasse Tyson:And depending on where and when they receive them at other stations, they can map the density profile of the entire Earth. Holy crap. Because the wave moves through dense materials differently from light materials. And once you know that, you can figure that out. And bada-bing, we've got an iron core. That's amazing. So we think we're about the density of water. Some people float. Some people sink. Humans are about the density of water. So we think of rocks as heavy, and relative to us they're heavy, relative to water they're heavy, relative to air, but not relative to the rest of the earth. That's why you don't have to have a mining operation to find rocks.

29:36They're sticking out of the side of the mountain. They have floated to the top of the earth.

29:41Neil deGrasse Tyson:They floated to the top, and they're there for the taking. And by the way, that's why it's so hard to find meteorites on earth's surface. because most meteorites are rocky. And so it'll land and it just looks like any other rock. So you got to go to places where they would stand out. And there are two kinds of places where that happens. One is the desert, sandy desert. Sand and rocks. One problem is that sand will cover it over often. However, sand will also blow away. And if you see a rock sitting in the middle, because you can scan like many square miles at a pop, okay? So you say, oh, there's something sticking out of the sand over there that just got revealed.

30:19Neil deGrasse Tyson:They'll go over it. It's probably a meteorite. Wow. Okay. A. B, another place you can go is Glacier Ice Sheets in Antarctica and in Greenland. So most meteorites in our collections, in our modern collections, come from Greenland and Antarctica for just that reason. Because every other place on Earth is made of freaking rocks. Right. So there's probably tons of them there, but they're just hanging out with other rocks. Because some people ask, how come all the meteorites are aiming for Antarctica? Right. Or that's like the thing. How come I only find my car keys near the lamppost? Right. At night.

30:57Neil deGrasse Tyson:Right. Well, because that's the only place you would have seen them. Right. Okay. But we're good. Wow, that was cool, man. Rocks are light. Rocks are light. Rocks are light, people. And pumas is even lighter because it's got air in it. Air is helping it out. Yeah, that's the fast solidifying rock from a volcano when it hits the ocean. It's also great for taking dead skin off your feet. No, I don't want... That's why God put boomers on this world. Exactly, man. That's the best use of it. Never mind that God could have made it so that you never got rough feet in the first place, okay? I didn't perfect that foot thing.

31:42Neil deGrasse Tyson:Let me give you something else to help that. Okay. That's the second round of creation, right? Okay. Yes, exactly. The first round was, you know, the actual body, and the second round was cosmetics. Cosmetics. For those days where even God couldn't help you. Yeah. It's like, hmm. I can't even do anything with this. Here, take some boomers. Take some of this other stuff. Right. You do it. You need L 'Oreal, baby. I can't help you. You need Max Factor. I cannot help you. You need oil of old age. Exactly. You need oil of old age. That's right.

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34:21Neil deGrasse Tyson:I got a topic for you. Okay. Warm blankets. All right. What is happening to us? What is going on that warm blankets are a topic? It's a topic. It's totally a topic. What's the next explainer going to be? Snuggling? I'm just saying. There's physics everywhere. And I just want to sort of bring warm blankets. Time has arrived to come to understand warm blankets. First of all, warm blankets sounds like a new emo band. and secondly, I am so... It's an underused title for something out there. Yeah, warm blankets. But I will say that I'm excited to see the physics in warm blankets. Okay, so here you go.

35:11Neil deGrasse Tyson:You ready? Okay, here we go. Okay. Here we go. When you look at a coat or a blanket or an item of clothing, so that's a warm item of clothing. Right. Obviously, when it's sitting on the hanger, the temperature of the clothing is the same as the temperature of the air. Okay. Okay. So you don't say, oh, that's a, if there's a blanket sitting on the tile floor, you don't say, oh, that's a warm tile. You say, oh, that's a warm blanket. But they're the same temperature, right? If they're just sitting out there in the air, they'll be the same temperature as each other. So why are we thinking the blanket is warm, but the tile is cold when they're the same temperature?

35:53Interesting. And the funny thing is we do make that distinction because you will look at the blanket and call it warm and call the tile cold or cool. Even though they're sitting there together.

36:08Neil deGrasse Tyson:They're sitting there together at the same temperature. Okay, so here's the thing. If the blanket were actually a source of warmth, you could put it over the tile, wait a while, peel back the blanket, and then the tile would be warmer than the surrounding tiles. Now I just picture tile on the floor just going, oh, man. Snuggling tiles. Oh, that was so good. I'm tired of people calling me cold. Oh, man, why did you do that? Why did you put the blanket back?

36:40Neil deGrasse Tyson:So the point is the blanket doesn't make anything warm. It is completely passive in this. it's not a source of warmth. If it were, you could put it on something cold to warm it up. True. That's all I'm saying. It is not a source. It is not a source. Even though our language calls it a warm blanket or warm mittens or warm anything else. Okay. So what we really mean when we say a garment is warm is that it does not transmit heat energy. Right. That's all we mean, even though that's not what we're saying. Well, first of all, that doesn't sound very comfortable. I just want to get under a blanket that doesn't transmit heat energy.

37:37Come on.

37:40Neil deGrasse Tyson:A new catchy ad for the blanket commercial, right? Come on under here and let's get under this thing that doesn't transmit heat energy. So there's the point. If you put the blanket on the tile, there is no heat difference between them. So nothing is happening. Okay. So now watch. Now I put it on you. So you are warmer than the blanket. if you got the blanket out of the closet or on the shelf. The blanket is just room temperature. You are warmer than the blanket. And right now, you are radiating heat to the air. Yes, I am. Losing heat. Because I am hot, baby. No, you are radiant. I am coming in hot.

38:27Neil deGrasse Tyson:Coming in hot. That's what I am. So you come on in. And so you feel cold because you're losing heat to the air. Okay? And then you say, oh, there's a warm blanket. Let me go get it. So now you bring the blanket. And now the blanket doesn't let you lose the heat to the air. You keep that heat. And you interpret what's going on as the blanket being warm. When all that's happening is that you are no longer losing the heat you were a minute before you put on the blanket. Now, you might say that's just semantic. No. Okay? Because let's say you brought in some cold beer. Okay? Okay. And you don't have any ice yet, but you got it out of the refrigerator cabinet.

39:18Neil deGrasse Tyson:It's cold beer. It's sitting on the floor. And you say, I don't want the beer to warm up. Let's get a warm blanket to put on it. Okay?

39:31Neil deGrasse Tyson:Because how does the beer get warm? It's taking heat from the air. Okay? Because the air is warmer than the beer. So what you need is super blanket that does not transmit heat energy across its thickness. So you take a blanket, put it on the beer. It'll keep the beer cold by preventing heat from coming from outside of the beer, from entering the beer. Oh, man. So. So the point is, so the blanket that you're calling a warm blanket is also a cold blanket. It's a cold blanket, too. And by the way, we have another word for things like that that you carry around, and it's called a thermos. Okay, that's true.

40:12Right. Yes. Whether it's a thermos cooler or a thermos for liquids.

40:17Neil deGrasse Tyson:It's the thermos keeps hot things hot and cold things cold. Cold things cold. Right. The thermos is the ideal blanket for the food that's contained within it. so if you wanted the if you wanted the best bed of them all turn it into a thermos it's just not cuddly but boy you will stay you in fact you'll become too hot because your body needs to actually cool off otherwise you'll overheat so i just wanted to clarify the fact that warm blankets are simply blankets that don't transmit heat energy and it'll work keeping your beer cold or you warm. And more broadly, it'll maintain the temperature of whatever it is it's covering.

41:01Neil deGrasse Tyson:There it is. And if you're not having a good time, then that's a wet blanket, but that's a whole nother explainer. Whole nother explainer. That's another, whole nother, another. So basically, this is what insulation is. Insulation. We don't think of blankets as insulation, but that's what they are. And if one blanket is not working for you, you get a second blanket. So the two combined make it even harder for heat to transfer from one place to another. Okay, so now how does that explain why no matter how many blankets I put on my wife, her feet are still cold? We have top scientists working on that right now.

41:48How can you be feet cold? You're wearing boots, thermal socks, and three blankets. How are your feet cold? Impossible.

41:59Neil deGrasse Tyson:So we may have talked about this in another explainer, Chuck. I'm not sure, but you will feel cold if you are losing heat to your environment. Right. And you will feel warm if you are gaining heat from the environment, or Or if your heat does not lose to the environment, has a hard time leaving your body going into the environment. Yeah, we talked about that during wind chills. Wind chill, we did talk about that. Yeah, we talked about that during wind chills. I had some memory of that. So warm mittens, you know, what makes mittens warm? They're keeping your fingers touching each other. Right. In a mitten, when one finger loses heat, it goes to the next finger.

42:42Neil deGrasse Tyson:Right. Well, you want that heat. So you're radiating to yourself inside the mitten, right? Whereas gloves, where all your fingers are separated, it's trying to prevent your skin from making thermal contact with the air. But you have all this surface area on each finger for each finger of the glove. And so that's why it's harder to keep your fingers warm in gloves than it does in mittens. That's all this is ever doing. And that's a wonderful metaphor for where we are in America right now. America, the country that prides itself on being a glove where each finger is independent of one another. When right now what we really need to be is a mitten, each one of us giving heat to one another, relying upon each other in order to be warm together.

43:34Neil deGrasse Tyson:Kumbaya. Kumbaya.

43:42Oh, shit. I'm sorry. Chuck, I didn't think you had it in there.

43:48Neil deGrasse Tyson:Chuck, that was beautiful. That'd be beautiful. Kumbaya is great. I forgot about that. But what that means is if you jump into, if you have a partner in bed who's been there for some time, holding aside your wife's feet, which top researchers are still working on, If you have a partner that's been in bed under the covers, under the, quote, warm blanket, and you've been outside, and you feel cold because you're losing heat faster than your body is comfortable, and you say, I'm going to jump in bed. The moment you jump in bed, you will touch your partner and start taking heat from them. Right. The moment you start taking heat from them, you feel warm.

44:32Neil deGrasse Tyson:And you say, oh, honey, you're warm, and what do you feel like to her? Oh, my gosh. What I feel like to her is a call to her divorce lawyer. So you're taking heat from her. The fact that she's losing heat from you means she feels cold. Right. So two people cannot feel warm with each other at the same time. You can be neutral. One will feel cold, the other hot. One will feel hot, the other cold. But you both can't feel warm touching each other. Thermodynamically, that's not possible. Nor can you both feel cold touching each other. So somebody is either neutral or somebody is taking heat from the other.

45:11Right. Well, judging on my marriage, clearly we know who's going to be taking what from whom.

45:21Neil deGrasse Tyson:What kind of heat energy? Who's got what? I'm just saying. So that's it. That's all I got to say about blankets. All right. You pulled it off. I'm going to give it to you. So think of it not as a warm blanket, just as a blanket. As a blanket. And serving as a thermos in your life to keep the cold beer cold or the hot or you warm at your body temperature. One last thing before we wrap. Reptiles are the same temperature as their environment because they're cold blood. That's what cold blood means. It doesn't mean their blood is cold. It just means they don't regulate it and make it a higher temperature.

46:01Neil deGrasse Tyson:So it's the same temperature as the air. So you could put a blanket on a reptile, but it'll be vastly yet less useful to it than if it were warm-blooded. Well, now I feel bad about making my iguana wear a sweater. Damn, all that for nothing. All that knitting for nothing. How much knitting could that have been?

46:26Neil deGrasse Tyson:And just quickly, if the iguana goes out into the cold weather, you're going to want to bring him a sweater. because then they will be losing their body heat to the air, and maybe they don't want to do that at that moment. Right. Because they live that way, but maybe they want to stay warm. And snakes, you ever see snakes in the summertime? They'll come out and sunbathe on the rocks because that feels good. Right. But that's because a source of energy is being handed to them by sunlight. Right. You can't just give a blanket to a snake and say, you don't need the sunlight, just snuggle up in the blanket.

47:00Neil deGrasse Tyson:that's not going to work. Right. And the reason why you don't give a blanket to a snake is because they're a snake.

47:11Thanks for figuring that one out, Chuck. Right. They just, they don't deserve anything, damn it.

47:19Neil deGrasse Tyson:Don't give a blanket to a snake because it's a snake. What kind of reasoning is that? I don't like snakes. That's where that reasoning comes from. it's that simple alright there you go and what I learned is this if you are using a blanket to keep your beer warm I invite you to a little place called Walmart or Target to buy a cooler you wouldn't use the blanket to keep your beer warm you use the blanket to keep your beer warm I'm sorry I said it wrong damn it damn I messed it up damn anyway oh well alright be good Chuck This is great. StarTalk. Explainers. Over and out. Keep looking up.

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