Neil deGrasse Tyson Explains Heat vs. Temperature

[Music] chuck i got a good one for you uh-oh i'm ready it's it's a source of no end of misconception in our world in civilization oh so yeah yeah so it's a big one okay all right and it's the difference between heat and temperature they are not the same thing okay so you you have already you you're right uh because if you say that this is a source of misunderstanding then um i am the source because guess what heat and temperature i mean it's the same damn thing okay all right i will start off i hate starting off this way but i will um i'll start off defining them from the point of view of a physicist okay all right all right so the temperature of the thing is the average kinetic energy of its vibrating molecules okay all right so you have a thing that is of a temperature you go you look in close all the molecules if they're atoms it could be atomic they're all vibrating they're riding fast dividing slowly okay you put a thermometer in there that vibration gets communicated to the thermometer the thermometer reads a temperature is the average kinetic energy the average energy of motion of the vibrating particles the average which means a single particle has no temperature okay okay wait a minute a single a single particle that's right there's no this it doesn't meet right so temperature is a macroscopic thing that you obtain from a from a from a liquid a solid a gas it doesn't matter okay that's temperature okay okay so you heat it up some more you get higher temperature oh by the way there's a range of at which they vibrate some vibrate slowly some vibrate quickly it's the average that's the temperature uh let me say that another way at a given temperature uh there's a like a a the average which is where most of them are kind of vibrating and then there's some off at the tail some are vibrating slowly some are vibrating quickly okay okay here's an example okay let's get water at let's stick to fahrenheit let's say we are 200 degrees water no room temperature water 75 to 70 degrees okay here you go some of those water molecules are vibrating very fast others very slowly okay right some of them are vibrating fast enough to escape right yes okay but it's just those only at the at the edge did they escape they're at the very top right at the very top they'll escape the rest are stuck right okay so now they escape this is evaporation correct and you don't have to be boiling water to evaporate the water because the fastest moving molecules are always escaping okay that's right okay also just while we're there if you are a low mass atom or low mass molecule relative to high mass molecules your low mass winds are vibrating even faster on average you can split them up the heavy ones are moving slowly the light ones are moving quickly the average of all of them that's the temperature so funny how even atoms work kind of the way uh every molecules work the way we do you know that the heavy ones kind of slow you just kind of chill [Laughter] and the lighter ones are for example our atmosphere has both oxygen and nitrogen in it and the oxygen molecule weighs slightly more than the nitrogen molecule okay so on average if you separated out the oxygen it would be at a lower temperature than the nitrogen but mix them together you only get one temperature because there's a mixture that's all i'm saying about temperature okay okay so heat let's go to that individual vibrating molecule and say how much energy you got write down that number let's go to the next one how much energy you got write down that number and just keep doing it for every molecule every molecule in your soup so it's not okay gotcha so so the sum of all the kinetic energies of all the vibrating molecules that's how much heat is in the thing gotcha okay so one is an average the other is this the actual number the sum of all the so your cup of coffee in the morning at 210 degrees fahrenheit right is hotter than the ocean but the ocean has more heat oh snap it's hotter than the ocean but the ocean because the ocean has more molecules and you're going to add up some you add up the sum of all the molecules total molecules okay that's why your coffee cup your coffee cup is not going to start a hurricane right it doesn't have enough energy in the coffee cup to make that happen and that and that heat that is all the energy in the ocean oh my gosh and that's why the ocean can start a hurricane but your coffee can only make your morning very bad because it's spilled in your lap or it can speed up your digestive tract and you're stuck in the car when you gotta go coffee has other consequences to your life about that part that's the last time i drink coffee and get stuck in traffic oh so that is a very important so now watch what happens so so now we have climate change where the the world is heating right and you can say okay um how much did the of the air we don't want the air to go up by two degrees celsius whatever because that could trigger other changes well let's check the ocean how much did the ocean go the ocean went up a fourth of a degree or like a half a degree and you're saying to yourself that's not much right do you know how much total energy that is oh my god that is oh my gosh okay so chuck that's why when you're trying to create the energy budget of a climate system right there's sunlight coming in and it warms the air is that where all the energy goes no no all the whole there's energy that goes into the ocean and it can hang out there lurking all right so you could you could reduce your carbon footprint and reduce the warming of the atmosphere then the ocean says i got heat i can dump into the atmosphere and i can keep doing this even after you have corrected your behavior to protect future generations and the balance that it's actually an imbalance at this moment the the relationship between the the heat that the land retains and the atmosphere and the oceans the ocean winds every time right because of it's it's this tremendous heat reservoir so i just wanted to distinguish the difference between heat and temperature and there's one little thing you might not know okay okay um do you know air conditioners right it's like it's hot outside and it makes you cool on the inside okay yes okay all right do you ever ask how it accomplishes this um not really all i know is you just turn it on i just turn it on and it works and uh from the time that i was a kid i know that uh you don't leave the door open because we're not trying to cool the whole neighborhood what the hell you think we're trying to cool the whole neighborhood shut the door chuck i thought you had finished your therapy on your childhood experiences but apparently some sessions remain uh so here so what's happening there is okay there is heat inside of your room no matter what temperature your room is as long as it's above absolute zero there is heat there heat there's a pump that takes that heat removes it from your air and sticks it outside that's why no matter the temperature outside if you feel the air conditioner it's hotter at the air conditioner why is it hotter because it just pulled that heat from your your 72 degree room temperature room that you're trying to keep cool it pulled it out and it can reverse that okay so let's reverse it it's called reverse it's a heat pump a reverse heat pump in your winter okay you want it to be warmer in your room than the outside once you switch the heat pump your air conditioner says okay let me take heat from this cold air out there it's 40 50 degrees i don't care let's take heat from that cold air and put it in your room and make your room hotter even hotter than it would otherwise be compared to the outside it can do that because there is heat there no matter what the temperature is as long as it's above that as long as it's above absolute zero that is okay it's clever engineering just think it is brilliant go hug hug your favorite engineer this is where this comes from brilliant okay so i'm gonna admit that when we started this i was like this guy has really dug a hole for himself this time no way no way this is going to be interesting okay but i gotta admit this is great next time you're sipping a cup of coffee looking out at the ocean yeah just just think to yourself just know that that ocean has more heat than this hot scalding cup of coffee you could burn yourself with the coffee but the hurricane won't it won't matter to the hurricane that's right wow that is so cool man that is cool all right that's a quick one you got it so chuck that was an explainer video on heat versus temperature the physics and the engineering of it all right we got to break it there i'm neil degrasse tyson bidding you to [Music] keep

Channel: StarTalk

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Id: yzUFXcC_P2Q

Length: 11min 13sec (673 seconds)

Published: Tue Mar 02 2021