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A better description of entropy

  • Published on Mar 27, 2023 veröffentlicht
  • I use this stirling engine to explain entropy. Entropy is normally described as a measure of disorder but I don't think that's helpful. Here's a better description.
    Visit my blog here: stevemould.com
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  • Science & TechnologyScience & Technology

Comments • 4 308

  • Gordon X. Frohman
    Gordon X. Frohman 6 years ago +6122

    The reason that train isn't moving is because the driver wants to postpone the heat death of the universe by not increasing entropy.

    • Alexandre Kassiantchouk
      Alexandre Kassiantchouk 2 months ago

      Free "Time Matters eBook" takes time even further, time itself is the primordial energy and the source of matter: 1950s Fermilab experiment is reinterpreted as time burning into matter. In a sense, time is much alike as temperature. (Slow time is more energetic than fast time, and time in the Universe speeds up by losing its energy to matter created.)

    • Daren Miller
      Daren Miller 2 months ago

      Haha nice. That conductor knows where the universe is heading and will be our only savior.

    • Aben Zin
      Aben Zin 4 months ago

      Nono, the REAL reason that the train isn't moving is that he's in the UK!

    • Jack Myers
      Jack Myers 5 months ago

      It's because his own dissemination of information represents such a massive organization of neural energy. not only his own. but of everyone who watches it. that the zero-sum nature of energy within physical existence would have led the resulting chaos into his own home. The delay in departure was likely the motivation for his recording and the lack of disturbance prevented a re-recording, and now. as we remember this video. we create a feedback loop of consciousness where the universe will compel itself into the exact state of circumstances that caused the event, Plus. being in a big metal tube with a hearth gives the entropy someplace to go.

    • Flying Fox
      Flying Fox 8 months ago

      No, it's because Steve stole their engine.

  • Phillip Arab
    Phillip Arab Year ago +100

    This really bridged the gap for me between the statistical “ping pong ball” analogies ive heard, and the teachings of physically irreversible processes when describing entropy. Great video!

  • TheClearsky88
    TheClearsky88 Year ago +72

    I have a degree in mechanical engineering from a respectable university. I did thousands of thermodinamical calculations using entropy. Yet, you helped me understand entropy better... thank you!

    • Wildfire
      Wildfire 20 days ago

      I like how ppl complain about spelling, in a time when AI is almost ready to spell correct everything. Worrying about spelling is about the dumbest thing you can do.
      Also, I'm an astronaut millionaire.

    • Quixote
      Quixote Month ago +1

      Did entropy increase when you substituted an “i” in “thermodynamical” for the “y”? Or, maybe you’re an engineer, not an English major :) ?

  • Allan
    Allan Year ago +49

    My favorite definition of entropy cames from Shannon which roughly is the amount of information of a system, or how much you can compress information in a system. This is also consistent with the entanglement network we have as our reality, and its information increase over time attempting to "write" information on its state.

    • Thomas Harris
      Thomas Harris 11 months ago +6

      Yes. There is a great story about that. I think it was von Neuman who suggested that they call that Shannon's phenomena Entropy because of the similarity to the equations of (mechanical) entropy. So Shannon Entropy was discovered later and was only called Entropy as an analogy. But really it is more fundamental I think. You can explain thermodynamic Entropy in terms of Shannon Entropy but you can't really explain Shannon Entropy in terms of thermodynamic Entropy.

  • Jack Addie
    Jack Addie Year ago +12

    Thank you so much for this video Steve! Studying thermodynamics at uni right now, and this video is the ONLY one that I have understood. Physics, nature and our universe is just so beautiful, and your video made that ever more clear to me!

    • mama mia
      mama mia 4 months ago

      Surely you would have known this before studying that at uni, right?

    • Graeme Morrison
      Graeme Morrison Year ago

      I wish we had Clip-Share when I did my physics degree thirty five years ago. It would have made many concepts less of a struggle to get my head around (And I probably would have got a higher classification!)

  • Deth Engine
    Deth Engine Year ago +6

    Thanks, Steve! I had the basic idea, but you really brought it home for me. And that was a nice tie-in to the heat death of the Universe.

  • Kayla Evans
    Kayla Evans 2 years ago +1068

    What I came for: better understanding of entropy
    What I left with: existential anxiety about the heat death of the universe

    • Ays
      Ays Month ago

      Want more existential anxiety? It is infinitely more likely that you and the room you are in are actually the only thing that exists in the universe, having spontaneously appeared out of a statistical fluctuation moments ago, and are going to disintegrate before you can finish reading this, than the universe as (you think) you know it actually exists.
      This will still be true at any point in the future, as you can never know whether your past actually exists or you just fluctuated into existence with fake memories.

    • a b
      a b 5 months ago

      I hate how the reaction to existential anxiety is to make it worse by reminding people of their mortality.

    • Will George
      Will George 8 months ago

      Well, What's the average temp of the universe and what temp are you? The sun? centre of the earth? all much hotter, so we already beating the "heat death"!

    • Badoumbe Soumbounou
      Badoumbe Soumbounou 9 months ago

      Idk how to spell it lol

  • SaintBrook
    SaintBrook 3 months ago +3

    You ought to do a video about that sodium acetate hand warmer you used. They’re really a pretty brilliant example of the latent heat of fusion given off when you have a phase change from liquors to solid. Orange farmers in Florida use the same phenomenon in water to protect oranges from freezing. They spray water on them and when the water freezes it keeps the oranges from freezing.

  • The Observer
    The Observer Year ago +9

    This has to be one of the best explanations for entropy I have heard so far!

  • Steve Wolfe
    Steve Wolfe Year ago +4

    I have that engine plus another Stirling. Now I know how to introduce my grandkids to entropy. A great explanation that helps one visualize. My intro to entropy was in 1967 2nd year thermodynamics in a classical physical sciences program. The prof was really good but visual props were limited to spelling out Noel complete with the 2 dots over the e in a pre-Christmas review of various equations

  • muayyad alsadi
    muayyad alsadi Year ago +3

    Yes! This is what am talking about. Entropy is increasing not about disorder it's about fair even distribution or spread out. And this also applies to abstract things, for example a high entropy random generator is well spread out evenly. A high entropy checksum is also well spread out that a small change in input make much of the checksum to change into any possible value.

  • Maanik Khurana
    Maanik Khurana 6 months ago +2

    Hey mr.steve i really like your in depth definations the afterwards knowledge we have after watching your videos is just off the charts really appreciate your hardwork and thanks for educating these various complex yet beautiful topics hats off to you man

  • evilferris
    evilferris 2 years ago +496

    This particular way of describing entropy is why you always find your earbud cords always tangled up: *there’s only 1 way* to have the cords straight and untangled but, as you jostle them around in your pocket or backpack, *there’s a myriad of ways* for them to become tangled.

    • Lasse Sipilä
      Lasse Sipilä 14 days ago

      @Joel Wexler Must be nice. How's the swoosh of the wind up there?

    • Joel Wexler
      Joel Wexler 14 days ago

      @Lasse Sipilä That's fancy sounding, but I think I always get it on the first or second try.

    • Kiwi Guy
      Kiwi Guy Month ago

      But my shoelaces keep coming undone 🤷‍♂️

    • dav ep
      dav ep 4 months ago

      @drakedbz So, if you keep it untangled it remains untangled ;-)
      I often do an, albeit, non-meticulous wrap and it doesn't seem to help. In fact, it *seems* like it either comes out much less tangled or much more tangled. Even though corded 'phones sound 10^6 better, wireless is rarely tangled. No jokes about entanglement.

    • dav ep
      dav ep 4 months ago +1

      @Daniel Terra However, it does explain the existence of USB C. Imagine all of the saved time and effort (energy) it will result in. The universe (and economy) will be glad we aren't wasting time, shining lights onto jacks, or for us olde fartes(tm), pulling machines away from the wall, etc.
      USB C, savior of the universe, and kick in the stem of Apple(tm).

  • DaltonEU1
    DaltonEU1 3 months ago +13

    Thank you for explaining this so clearly!

  • Richard Reynolds
    Richard Reynolds Year ago +5

    Always watch Steve's videos until the very end. Don't ever leave the video thinking it's basically over.

  • James Wack
    James Wack Year ago +11

    I just recently purchased a Sterling Engine model (and a Tensegrity Table) to Science educate my grand-kids (they'll face challenges greater than I've faced, and I'll be 'gone' in 20-30 years, optimistically). In the course of exploring, THIS post was suggested... and I've shared. Thank you!! I feel it was brilliantly explained and worthy of interest. Just sitting on a train, in a station, not moving yet... and an 11 minute compilation of Brilliance I just discovered when I needed it.

  • Ujjwal Gaur
    Ujjwal Gaur 4 months ago +1

    Thank you for such an awesome explaination about entropy , we learn in our high grades just about the definition, not knowing the actual meaning of it .

  • Timothy Hughbanks
    Timothy Hughbanks Year ago +1

    I gave my Second Law lecture to my Freshman chemistry class this morning and that is exactly the way I say it too: increasing entropy is about spreading energy out. Our illustrations are at the molecular scale, but it always comes back to energy spreads out because states of the system that overwhelmingly most likely are those with the energy spread out.

  • Ron Stoppable
    Ron Stoppable 4 years ago +816

    I've always disliked "disorder" as a description for entropy, When energy distribution is homogenized, with everything spread out evenly, that's about as orderly as anything can get.

    • Andy Williams
      Andy Williams 15 days ago

      Specificity and homogeneity make more sense to me

    • Radijator
      Radijator 23 days ago

      Thank you, holy shit, i fucking hated arguing over this

    • Johannes Näsman
      Johannes Näsman Month ago

      I think of it as 'balance'

    • Unaussprechlicher Name
      Unaussprechlicher Name Month ago

      No, that’s maximally unordered. You can’t distinguish anything anymore.

    • Emil Arpi
      Emil Arpi 2 months ago

      Yet I wouldn't let entropy order my money..

  • Bull Compost
    Bull Compost 2 months ago

    Absolutely great video! Not only your definition of entropy is, in my opinion, a lot better than the "measure of disorder" one, but also yours was the very best explanation of how the Stirling engine works (I love Sterling engines).
    Your way to explain stuff is second to none.
    Thank you.

  • Chris T
    Chris T 2 months ago

    Thanks for the clip! I've got a formal training in theor. physics including Ph.D., so I have learnt both the microscopic-statistical "measure of disorder" (correct but not easy to turn into useful calculation) as well as the thermodynamic, blackbox-process-motivated "state quantity that varies with dQ/T" (also correct, and more useful, but somewhat distant from getting an intuitive understanding).
    I keep struggling with forming an intuitive (yet quantitative and correct) grasp of entropy. Your clip helped, but I keep struggling.
    Energy is much easier in this respect. It's simply a conserved quantity.

  • The Pilot's Life
    The Pilot's Life Year ago

    What a kind, simple and entertaining way to explain things. Thank you, enjoyed it :)

  • naduah
    naduah Year ago +2

    I remember in high school a girl in my physics class concluded half jokingly that everything would eventually end up as heat, and the teacher agreed. Never knew that it was called entropy tho... Cool video!

  • Fergal Byrne
    Fergal Byrne 2 months ago

    An actually good explanation of entropy. Thank you 🙏

  • Angelo Collins
    Angelo Collins 5 years ago +1432

    I'm an Aerospace Engineer, studied at the University of Maryland. This is by far the best explanation of Entropy I've ever heard. You get into another level of complexity when solving for Entropy (S) as a function of heat transfer (Q) and absolute temperature (T), but having this foundational understanding gives context to really comprehend your solution. Good stuff!

    • Angelo Collins
      Angelo Collins 5 months ago

      @Seth Hi Seth, where did you end up going to school? Let me know if you need a job! I'm at Booz Allen and I work at DARPA.

    • clark thomas
      clark thomas 5 months ago

      If entropy is universal, why are there huge complex strands of galaxies in space?

    • Shri Hari R
      Shri Hari R 2 years ago

      Yo.. Can i get you insta man?😄

    • Ebubechi Oti
      Ebubechi Oti 3 years ago

      Ahhh Thermodynamics 1 and 2 fun times at uni

  • Marc Rover
    Marc Rover 3 months ago

    Great video.
    Something not mentioned in this video, which is also interesting, is the relationship between "meaning" and "entropy."
    In other-words, the more disorder something has, the more potential it has.

  • Al Ger
    Al Ger Year ago

    Recently found, and subscribed to, your channel. Good goodness but this is a much more reasonable definition of entropy. You've added a bit of happy to my world. Thanks, dude!

  • Sean Devlin
    Sean Devlin Year ago

    Far out. You've explained a lot of my questions about Entropy and have got me thinking about other questions now. I must delve deeper into the subject. Thank you sir.

  • Anusha Kabber
    Anusha Kabber 2 months ago

    Absolutely love your way of defining entropy!

  • XComPointer
    XComPointer Year ago +1

    Yes youre right this is the best explaination of entropy! I was intrigued by entropy since i first heard it in thermodynamics class. I think none of us in that class really understand what entropy is nor theyre interested since we're civil engrs not mechanical. But not me i was always fascinated what entropy is

  • P Hampton
    P Hampton 6 years ago +721

    Entropy increases and so does my understanding of entropy, thanks to this video!

    • Anon54387
      Anon54387 4 years ago +4

      @Erick Lopes Usable energy anyway. I suppose that's splitting hairs, though. Entropy increases as one runs steam through a turbine and enthalpy decreases. Then one condenses it and pumps it back to the boiler where entropy is decreased and enthalpy increased so it can be sent back to the turbine to do more useful work. Enthalpy is order and thus usable energy where entropy is disordered unusable energy.

    • Blaze
      Blaze 4 years ago +2

      Erick Lopes yep

    • Erick Lopes
      Erick Lopes 5 years ago +4

      Battery charged: Low entropy
      Battery discharged: High entropy?
      So entropy is kind of the opposite of available energy?

    • Lou F
      Lou F 5 years ago +2

      P Hampton I don't want to play with that fire too much, but there is following phenomena: syntropy. This the new organization. E.g. when one's organization gets bad, and it gets reorganized; etc...etc...

    • Steve Mould
      Steve Mould  6 years ago +90


  • Ranul Hashika
    Ranul Hashika Year ago

    I always had a problem with the general description of entropy "measure of disorder". Thank you for this video.

  • Conrad Pinto
    Conrad Pinto Year ago

    Very late to this video as I discovered this channel only 2 days ago but damn, this was one of the best explanations of entropy I've watched/read. Subscribed!

  • Shahid Meir
    Shahid Meir Year ago

    Being a mechanical engineering student. I have studied alot of thermodynamics and i found this video the best explanation of entropy.
    Thank you

  • Asha R
    Asha R Year ago +5

    I remember I've always been wondering what entropy really is because wether a room is messy or not is subjective, the word disorder is also kind of subjective.

    • Awestrike
      Awestrike 4 months ago

      The degree of disorder that qualifies as messy is subjective, but the fact that "less disorder is less messy" is the objective part. If someone splashed paint on your wall it would be considered messy, until you find out their name is Jackson Pollock. In that case, there are relatively few random configurations that are similar to this highly specific, one-of-a-kind work of art.

  • Dylan
    Dylan Year ago

    This was a better description. I was always puzzled by entropy being classified as disorder because disorder is just human defined

  • ruchir rawat
    ruchir rawat 2 years ago +153

    This is the most intuitive video on thermodynamics I've ever watched. Thank you for finally making me understand what entropy is : )

  • Llewelyn Bendtsen

    I like the ping-pong ball box analogy, as it's also useful for explaining Chaos.
    You could fill the box with half red and blue balls in the same way, and use a machine to precisely shake the box, then note the position of the balls. Put the balls back in their half/half configuration, and repeat the exercise. The chances are the balls will settle into a different position every time, and you never effectively predict where the balls will land. This system is chaotic.
    Now I think that arguably, if the balls are set up precisely enough, and the box is maintained precisely enough, and the machine shakes precisely enough, and the temperature is precisely maintained, and it can be isolated from all external interference, perhaps you could predict the outcome of the test, and get the same result each time. However even the tiniest change in any factor will produce wildly different results, such that we cannot conceivably engineer such precise conditions to make the outcome predictable, even if we had an inconceivable amount of analytical computing power. That is chaos.

  • Stay Curious
    Stay Curious 4 months ago +1

    Hi Steve. Thank you for always posting interesting content. This had my attention from start to finish. I have just one issue with your final thought. A closed container with the content at equilibrium will still have random movement and snapshots of the distribution of atoms would change over time. I think that time would continue even after equilibrium is reached. I might be wrong though. 😅

  • (•⁠ᴗ⁠•)

    So about the pingpong box, if the red ones are all given a piece of ferrous metal and the blue ones are given non-ferrous ballast and you attach a magnet to one side before shaking, will the magnet eventually lose its magnetism and essentially "wear out" from use due to the force it exerts to sort the pingpongs? I'm checking out your three videos on magnetism now, but I think that's a topic that could use some more love from you! I have a hard time grasping electromagnetism in particular, so I hope you'll get inspiration for more videos on that general topic because you're one of the best folks I know with regards to explaining fundamental phenomena.

    SBTOPZZZ LG 10 months ago

    Really informative video, makes the concept of entropy so understandable. Thank you.

  • Caleb Henry
    Caleb Henry Year ago +1

    Super well done! I love that definition!

  • Ajay B R
    Ajay B R 3 years ago +751

    Sir, you are a huge clump of energy and enthusiasm!

    • Alex Embiric
      Alex Embiric Year ago


    • Chakri V
      Chakri V 2 years ago

      Once we watched this video and understood it and are as clever as him in this particular 11:42 mins of subject, we will not watch it again, does that prove knowledge or emotional entropy

    • Praveen b
      Praveen b 2 years ago

      But Steve is an exception to the rule - he spreads the energy around all the time, but it never loses its magic.

  • J. Curtis
    J. Curtis Year ago

    At a chem undergrad level, I have always spoken of dispersal of both energy AND matter - the latter being helpful in illuminating the mathematical calculation of gas expansion entropy and entropy of mixing for gases or liquids (and same idea applies to heat energy dispersal via black body radiation emission).

    DZR NUTRITION 6 months ago

    Have been wrapping my mind around the unlogical definition of increased disorder and have been stumbling on getting the meaning really, until I saw this, thanks for this video really

  • Benjamin Gardner
    Benjamin Gardner Year ago

    This explanation is the physics perspective, and I easily understand it. The chemistry perspective I am absolutely confounded on. However, I am far better at chemistry than physics, like A+ vs D- or Fs. Conceptually, physics makes perfect sense to me. Mathematically, chemistry is a very straightforward, stepwise series of actions. Neat how the mind works, and by working I mean increase universal activity through metabolic action. This video also makes me think we are entropic accelerators, and that is the definition of life, that which increases entropy beyond the threshold of unaided phenomenon.

  • Flaming Burrito
    Flaming Burrito 2 months ago

    I always understood entropy as stability. Once full entropy is achieved, the universe will reach a completely stable state, no change in energy, no reactions, perfect uniformity and stability across the board.

  • Reggy ReptinaLL
    Reggy ReptinaLL Year ago

    There are terms for piston positions, such as TPD top dead center, BDC bottom dead center. The foam block appears to working in the opposite direction of the cylinder.

  • Dragos Puri
    Dragos Puri 6 years ago +494

    Probably your best video yet. Very well explained, with great examples. Great job Steve! Waiting for the next. :)

    • Calmspace
      Calmspace Year ago

      Great job steve.
      Job steve
      Steve job.

    • Stroheim333
      Stroheim333 5 years ago +1

      Japeking1: I grant you, oil and water doesn't mix or melt together even in zero gravity.

    • japeking1
      japeking1 5 years ago

      The separation of oil and water only takes place when their is a gravity gradient and the apparent increse in order comes at the expense of a decrease in gravitational potential energy.... an overall increase in entropy.

    • Stroheim333
      Stroheim333 5 years ago +3

      I somewhat go with Electro-Cute here. Probably Steve Mould's descriptions of entropy is better than the conventional one, but it is not perfect. I always think of entropy as energy striving for equilibrium; and if it is impossible for one form of energy to reach equilibrium with another form of energy (the example with water and oil mixed together in a glass) each energy form still find the best equilibrium state in relation to each others -- the water for itself at the bottom of the glass, and the oil for itself at the top of it.

    • Ben C
      Ben C 6 years ago

      OK I have to admit to being slightly didactic with these questions as I already know a bit about the answers. Both examples are from Penrose's books. The oil and water example is from Cycles of Time, which has several really good chapters about entropy. When the oil and water separates out, the oil molecules end up with a higher velocity due to the strong attractive forces between them, and you have to take the velocities of those molecules into account as well as their positions. Entropy still increases when you look at the _phase space_ as opposed to just the _position space_ in this example. This is why you can't just think of entropy as "stuff not being spread out".
      The gravitation example is even more striking (and Penrose talks about it a lot in all his books) because this is the reason why entropy is (still) so low and what makes life as we know it possible. I don't know exactly how you quantify the entropy of the gravity in a system, but the basic idea can be visualized by thinking of those rubber sheet analogies people use to explain GR. A very smooth sheet with no kinks in it has low entropy compared to one that's all rucked up.
      The big bang resulted in a big ball of hot gas, very evenly spread out. That feels like a textbook example of maximum entropy. So why isn't it still just a big ball of hot gas evenly spread out? The reason is that when you take gravity into account, its total entropy was not high but incredibly low. Because of gravity the stuff clumped together and formed stars and planets with orderly motion, and hence night and day which provide our primary low entropy source for life on Earth. But all the time entropy was still increasing. The end-point of all this is black holes, which have the highest entropy possible (and there are some interesting theorems about this).
      Now deviating slightly from Penrose, who doesn't talk much about Shannon entropy, but sticks to more "thermodynamic' definitions, the only really convincing explanation I have seen about why Maxwell's Demon wouldn't work combines the thermodynamic and "information" ideas of entropy, and therefore I do think you have to consider them as being the same thing.
      So the thing about Mould's definition of entropy is that it's great for analyzing heat engines but that the common idea of "entropy being a kind of disorder" that he disparages is actually more general and I would say not bad at all as a starting point for trying to understand the idea.

  • Observ45er
    Observ45er Year ago

    There is not only one arrangement with all red on one side. Because the same colored balls are all each a distinct ball. When they are all on one side, you can still move them around into many different arrangements.
    Likewise, the other colored balls also have many different arrangements on their side, so you have twice as many arrangements with all of the balls of each color on one side. Therefore, it's not quite as simple as only one arrangement of the two colored balls separated on their own sides.

  • Eviscerator18
    Eviscerator18 Year ago +2

    As always, your videos are fun to watch and greatly educational. Thank you!

  • TooMuchPowa
    TooMuchPowa Year ago

    Really fun video to watch, made entropy easier to grasp.

  • Deer 🦌
    Deer 🦌 Year ago

    I have been always confused about entropy until I watched this video. Thanks for making it

  • 46
    46 Year ago

    9:16 if you think about it, depending on how many balls in the box, there is going to be many more ways than one as each ball could rotate once within its own colour to give you a second way amongst I’m sure many more but, obviously the number compared to an even looking distribution is far smaller.

  • Siddhant Chaudhari
    Siddhant Chaudhari 6 years ago +50

    As far as I know, out of all entropy videos, only this one mentions why the concept of entropy was introduced and gives a clear reason as to why entropy always increases. You are doing god's work my man. AWESOME explanation. :)

    • Steve Mould
      Steve Mould  6 years ago +6

      +Siddhant Chaudhari thank you :)

  • Julia Vieira Saliba

    after 20 videos I finally found one that is simple, complex and easy to understand

  • Tobias Reckinger
    Tobias Reckinger Year ago

    Our Thermodynamics Professor gave us a good mnemonic for S=Q/T. We should imagine the Entropy as the number of Ships (S) needed to transport a number of Containers (Q) with a Transport Capacity (T) per Ship. It sounds a little bit simplistic but it works for the most parts of Thermodynamics.

  • vestborgelev
    vestborgelev Year ago +1

    The ability to work against the laws of nature, rise up against gravity like trees and humans do or to consentrate energy locally like cells do, is one thing that I think separates life forms from dead matter. It is at least very fascinating that the few arrangements possible to construct these processes that work against gravity and reduce entropy, exists, when it is so so so unlikely, as you point out so well with the example of the red and blue balls. It's so fine tuned.

  • Neil Hawkes
    Neil Hawkes 5 months ago

    Very nice. The same thing has occurred to me. I am a research thermodynamicist, looking at buoyancy vortices as heat engines. Someone has to….😅

  • Veena Gawshinde
    Veena Gawshinde Year ago

    Such videos make me fall in love with science again and keep me motivated
    So yeah I'm thankful I found your channel 😀

  • j k
    j k 3 years ago +202

    I finally understand, after so many videos and articles - now, the clumped energy of my frustration has been dispersed! Thank you!

    • Sandeep Mandrawadkar
      Sandeep Mandrawadkar 2 years ago +2


    • P Daddy
      P Daddy 3 years ago +2

      It would be very nice if there was a universal law that said frustration would always tend to become dispersed. It seems the opposite may be true.

  • Daemian Greaves
    Daemian Greaves 7 months ago

    Thanks for this video! It is a much better explanation of entropy than the one we learned at school. Just a super nitpick (to be fair, you used the term ‘for statistical rigour’ so I think I can make this point!) but having all the red ping pong balls on one side and blue on the other is not just ONE of the possible arrangements because each of the reds are interchangeable offering a very high number of possibilities of red on one side (and of blue in the other side which are also self interchangeable). But even that high number of possibilities is thoroughly dwarfed by the number of overall possibilities, therefore we never see it. That being said, obviously, I know you were keeping things simple!

    • TennisCoachChip
      TennisCoachChip 5 months ago

      Yes and double that, because the reds could be on either side with the blues on the opposite side. But it is thoroughly dwarfed by the total number of overall possibilities. Statistics you are a cruel mistress! Great video thanks!

  • S.R.
    S.R. 10 months ago

    Great video thanks. I am now wondering; How did the energies in the universe get organised in the first place?

  • Scritch
    Scritch 9 months ago

    We need more of this series!

  • Gloweye
    Gloweye 4 months ago

    My preferred definition was always "the uselessness of energy", since increasing it makes energy less useful. Which is pretty close to yours.

  • JackZero
    JackZero Year ago +14

    Now that I finally understand entropy I can say I'm lazy because I don't want the universe to die faster.

  • Sergio Rodríguez Cabezas
    Sergio Rodríguez Cabezas 3 years ago +153

    I watch this video before and after my thermodynamics class. Now I understand the video better but I have to say that you explain better than my professor!

    • Baraka Thiongo
      Baraka Thiongo 2 years ago +3

      @Steve O'Hare congrats on finally learning algebra

    • Steve O'Hare
      Steve O'Hare 2 years ago +7

      The problem with Professors is that they think everyone understands what they are talking about instead of realizing in comparison to himself they are all a class of Chimps sitting in front of him, this is why I couldn't learn Algebra at school, I do understand it now as a good mate that could explain things the way Steve Mould does actually taught me Algebra it in about 10 minutes when I was 28 lol.

  • Michael Bourne
    Michael Bourne Year ago +9

    That was really interesting for this reason: given the amount of time the Universe has until it's heat death, that is enough time to allow for the statistical possibility that all the red and blue ping pong balls order themselves just once, and when that happens (if) then that would be a scary amount of enthalpy that could suddenly become available. Given that the Universe is finite yet boundless (and really, really big) I know that conventional wisdom says that it cannot happen but in all the time available there could be prolific pockets of enthalpy eruptions. I wonder if that actually happens quite regularly at the quantum level... I'm joking of course, since the discovery that entropy can decrease over time in a quantum system and quantum effects can be used to "clean up the states of systems". Interesting huh :) What I wonder is that if the quantum example can extrapolate to the macro system, or rather how it does that, similarly to how known quantum effects extrapolate to the macro universe we experience around us...

    • FJ B
      FJ B 20 days ago

      Michael Borne,
      If i understood the question, it Still wouldn't allow me an answer, ie: i don't know . . .

    • Jodi Diehl
      Jodi Diehl Year ago +1

      My basic understanding is a star being born from gravity is the clumping of entropy...

  • Joshua Dunlap
    Joshua Dunlap Year ago +1

    Great simple explanation that really gets at what entropy means. I also like to think of entropy as what happens to energy as you move toward a state of equilibrium. At equilibrium, no energy interactions exist anymore. Similarly, energy itself is then a measure of how far you are from that equilibrium state.

    • John Smith
      John Smith Year ago

      "For a closed system." If you leave that out, you fail.

  • Oscar Leite
    Oscar Leite 2 months ago

    Amazing video Steve! One doubt: when you operate the motor in reverse mode, which plate will become hot and which one will become cold? (Assuming that in normal mode you just need a difference in temperature and not a specific plate to be colder or hoter than the other). Thx!

  • zaphod
    zaphod Year ago +8

    Thanks a lot for this impressive explanation! I've been strugglin' to understand entropy for years!
    But I'm still struggling how to create a perpetual motion machine. Could you help me with that in your next video? (But keep it private?)

  • roxes787b
    roxes787b 6 months ago

    For me what we learned in physics was that entropy is a measure of how multiplicity tends to increase. By multiplicity i mean number of ways e.g. particles can arrange themselves.

  • NZAdventureFamily
    NZAdventureFamily 2 years ago +20

    Steve you are so good at explaining difficult concepts! Could you do a video on pKa and pH please?

  • jdanielcramer
    jdanielcramer Year ago

    Well done, that Sterling Engine is really cool, but I’m surprised that the air inside of it is capable of expanding and contracting so quickly? 🤔

  • Avril Barker
    Avril Barker Year ago

    I love your videos and humour and I learn good stuff, thanks brother!

  • BuckyBall
    BuckyBall 4 months ago

    This is a really great, easily understandable and scientifically accurate explanation of entropy and is the one I think should really be given to physics students. However, it is less intuitively obvious as to what it physically means so I’d still stick with the disorder explanation for the general public and popular science.

  • Putin’s Gay Twin

    Wow. He made entropy so easy to understand.

  • Ray of Light 62
    Ray of Light 62 Year ago +1

    My description of entropy is:
    S = k log W
    where W is the number of microstates, k is the Boltzmann constant (found by Planck), and S is the entropy, of course...
    Another good description of entropy is a science fiction story by Isaac Asimov, entitled "The Last Question"...

  • Creede Caldwell
    Creede Caldwell 2 years ago +29

    Great explanation! Another fun tidbit is that "entropy" is also used to describe how much information is encoded in something. This seems counter-intuitive at first when compared to the heat death of the universe, but it makes sense if you compare it to Steve's example of the balls in the box. For example, your hard drive is in a more orderly (less entropy) state when it's empty and all the bits are zeroes; when you fill it with data it has more information but you also can't easily predict if any given bit is a zero or a one (more entropy). James Gleick has a great book on this for those with some "temporal entropy" to kill.

    • Belisarian
      Belisarian 2 months ago +1

      Indeed, I heard something similar when talking about compression of data. In short more you compress data, more you are reducing orderly, predictable parts, which means if you compress something to maximum then all you are left with is pure chaos.

  • Observ45er
    Observ45er Year ago

    It appears that the purpose of that foam plate is to move the air back and forth between the hot and cold plate. It wasn't clear what the foam did, but I think that's what it does. When the air heats and expands it pushes the Piston up that moves the foam to move the air away from the hot plate and over towards the cold plate so then it cools.

  • John Connell
    John Connell Year ago

    That was a great explanation of entropy. 👍🏻

  • Phil Clark
    Phil Clark 2 months ago

    Interesting side thought is how the initial tank of energy in the universe was initially provided and why it has not reached total entropy if always existed.

  • Silviu
    Silviu 2 months ago

    could you place the hotter plate in the sun and the colder slab in the shade to make it solar powered?
    also, could you connect the colder slab to a huge funnel to concentrate air flow around (too cool it down)
    also, could you make the wheel look a little bit like fan to promote airflow around the top slab (to keep it slightly colder than the hot slab)

  • drakedbz
    drakedbz Year ago

    I wonder whether you could use a sterling engine to power fans, such that the heat from a CPU would power the cooling of that cpu. I imagine it wouldn't do a good enough job, or we would see that everywhere by now.

  • Caleb Martin
    Caleb Martin 4 years ago +112

    Entropy is the property of energy to tend toward uniform distribution, rather than concentration. That's how I've always described it 🙂Great video!

    • G Gentry
      G Gentry 3 years ago

      Yeah thanks for your description. I also prefer concentration to dispersion instead of order to disorder

    • Isabel Kloberdanz
      Isabel Kloberdanz 3 years ago +3

      Yes. I always appreciate articulate, eloquent people. Thanks for this description.

    • Felipe Ferreira
      Felipe Ferreira 3 years ago +4

      its not only a property of energy, you could use for information too... or whatever that has a statistical approach.

    • Ben
      Ben 3 years ago +3

      @fluent_styles Endothermic reactions happen (in terms of energy levels, there's lots of equivalent ways to describe them) because more energy levels become accessible to the products as the reaction progresses, outweighing those lost in the reactants due to the loss in temperature. So, overall theres an increase in entropy (which is the log of the available microstates). More specifically, the ratio of the partition functions of the products and reactants increases with temperature and so at some point the equilibrium will favour the product (there's also an enthalpic contribution due to the boltzmann factor, but that's less significant).

  • technoway
    technoway 2 months ago

    I like your definition of entropy.
    You say, "It's not heat you need. It's a difference in temperature."
    However, the only way to have a difference in temperature is for one place to have more heat, or more specifically, more energy. The energy is often in the kinetic energy of molecules.
    I get your point that it's the difference that matters.

  • Manuel Manolo
    Manuel Manolo 9 months ago

    Personally I always thought of entropy as a measure of "evenness". Because everything takes the path of least resistance, molecules mix and heat is transfered everything becomes more even

  • Sam
    Sam Year ago

    I think the first thing people should realize is that Entropy is a "concept" rather than a fixed definition like a kilogram or a second. Watching this video and the video which Brian Cox made on entropy really helped me understand the concept of entropy.

  • Secret Life of Matt

    Actually, in his short story "The Last Question", Isaac Asimov explored the idea of entropy and how the problem of the heat death of the universe might be dealt with...

  • Leo Bieker
    Leo Bieker Year ago

    This really puts into light how terrible my thermodynamics teacher is at explaining this lol. Thanks!!

  • stu
    stu 6 years ago +214

    And here we find our Hero Cpt. Mould struck by the insane desire to clear up a basic physics concept during his daily train commute.

    • Mezmorizorz
      Mezmorizorz 3 years ago

      @Andrew Robertson I don't agree that this is obvious, and even if it was how does this explanation explain what happens when the two metals aren't the same? That's not at all obvious to me, and at this point I've had about two years of thermodynamics classes ranging from gen chem to graduate level statistical mechanics. I don't see how someone who is totally ignorant of the topic is supposed to arrive at reasonable conclusions from it.
      But really, the most damning thing is that this video simply isn't an explanation for entropy. What he is describing is not entropy. He is describing a consequence of the concept of equally probable microstates that happens to work well for the few systems he described and few others.

    • Andrew Robertson
      Andrew Robertson 6 years ago +11

      The context of the discussion and accompanying diagram make it clear that he is talking about two identical slabs of the same metal. He could, of course, divert to say that the thermal energy distribution would be different for slabs of different material but that would be unnecessary for this discussion (he's not talking about the relationship of thermal energy and temperature) and make the discussion overly complex.

    • Electro-Cute
      Electro-Cute 6 years ago +3

      I know that, it was allso kind of my point. Temperature is a thermodynamical perspective on a very simplified system.
      What the guy in the video said was that the systems will reach equal thermal energy distribution (or at least that is how I interpreted it). But that is only true for few special cases.

    • Walrave
      Walrave 6 years ago +3

      Electro-Cute high energy density doesn't mean it will transfer more energy to a material of lower energy density at the same temperature, it just means it has more energy states accessible to store energy. Two touching materials at the same temperature will have an even energy transfer in a closed system no matter what their heat capacity is. Their energy content will not converge unless the materials themselves decay into each other to form a homogeneous spread of atoms.

    • Electro-Cute
      Electro-Cute 6 years ago +3

      This video explains thermodynamics wrong. It is obvious that Steve Mould doesn't understand the difference between temperature and thermal energy.
      If you have a material A with a very high thermal capacity next to a material B with a very low thermal capacity then A and B will try to reach the same temperature, but not the same energy dencity.
      So in other word you will find a huge gradient between the energy density of material A and B, even when they reach the same temperature.
      Lets say that material A is much more dence than B and both have the same bolume. This means that it is more likely that the energy will be transfered from B to A than from A to B. Because there is more mass in A than in B that can hold on to the energy.
      So in the end it is all about probability. It is more probable that the energy will be transfered to the material of high thermal capacity than the one with low thermal capacity.
      The most probable balance of energy depends on the laws that governs the universe. In the case of two simple materials like this it is governed by the laws that define the property of different materials.
      In a hypothetical case our universe could be governed by laws that we may not allready know of; very complex laws that states that our universe is allready existing in thermal equalibrium.

  • Saintpaty
    Saintpaty Year ago +2

    Mr. Mould I'd like to make a correction to your information, when it comes to the internal combustion engine, it is explosive energy moving the piston down. The internal combustion engine, or if you'd prefer, the Otto engine, is ingeniously designed in such a way that has the pistons reset each other. When a chamber fires the piston is forced down, rotating the crank shaft, resetting it's fellow pistons, all in a fraction of a second. If air was able to shift from one side of the pistol to the other, the engine would not run. The same can be said for the Diesel and Wankel engines as well. Thank you for your time.

  • Keinan Navot
    Keinan Navot Year ago

    I’ve watched so many videos about the issue and read a lot!! This is by far the most coherent and brilliantly visualized explanation.

  • zahid babel
    zahid babel 11 months ago

    Measurement of dissorder seems abstract for me. Your explanation with this different way is better for me to understand. Thank you

  • My My
    My My 7 days ago

    I think Time is better defined by cause-and-effect. Effects always follow causes which gives Time its direction.

  • Pasindu Eranga
    Pasindu Eranga Year ago

    By far the best explanation of entropy on the internet

  • ******
    ****** 2 years ago +7

    Thank you I actually understood this. I've always thought that entropy was energy spreading out but then I heard the definition of disorder and chaos and I got really confused.

  • Code Bit Cookie
    Code Bit Cookie Year ago

    This video finally cleared my doubts. Thank you.

  • Tarun KS
    Tarun KS 10 months ago

    This video is highly recommended for high school students like me. Great explanation!!

  • Ganesh Bhujbal
    Ganesh Bhujbal Year ago

    Thanks for sharing this video, very well explained the entropy.🙏