The Most Misunderstood Concept in Physics

The Most Misunderstood Concept in Physics

One of the most important, yet least understood, concepts in all of physics. Head to to start your free 30-day trial, and the first 200 people get 20% off an annual premium subscription.

If you’re looking for a molecular modeling kit, try Snatoms – a kit I invented where the atoms snap together magnetically:

A huge thank you to those who helped us understand different aspects of this complicated topic – Dr. Ashmeet Singh, Supriya Krishnamurthy, Dr. Jos Thijssen, Dr. Bijoy Bera, Dr. Timon Idema, Álvaro Bermejillo Seco and Dr. Misha Titov.

Carnot, S. (1824). Reflections on the motive power of heat: and on machines fitted to develop that power. –

Harnessing The True Power Of Atoms | Order And Disorder Documentaries, Spark via YouTube –

A better description of entropy, Steve Mould via YouTube –

Dugdale, J. S. (1996). Entropy and its physical meaning. CRC Press. –

Schroeder, D. V. (1999). An introduction to thermal physics. –

Fowler, M. Heat Engines: the Carnot Cycle, University of Virginia. –

Chandler, D.L. (2010). Explained: The Carnot Limit, MIT News –

Entropy, Wikipedia –

Clausius, R. (1867). The mechanical theory of heat. Van Voorst. –

What is entropy? TED-Ed via YouTube –

Thijssen, J. (2018) Lecture Notes Statistical Physics, TU Delft.

Schneider, E. D., & Kay, J. J. (1994). Life as a manifestation of the second law of thermodynamics. Mathematical and computer modelling, 19(6-8), 25-48. –

Lineweaver, C. H., & Egan, C. A. (2008). Life, gravity and the second law of thermodynamics. Physics of Life Reviews, 5(4), 225-242. –

Michaelian, K. (2012). HESS Opinions” Biological catalysis of the hydrological cycle: life’s thermodynamic function”. Hydrology and Earth System Sciences, 16(8), 2629-2645. –

England, J. L. (2013). Statistical physics of self-replication. The Journal of chemical physics, 139(12), 09B623_1. –

England, J. L. (2015). Dissipative adaptation in driven self-assembly. Nature nanotechnology, 10(11), 919-923. –

Wolchover, N. (2014). A New Physics Theory of Life, Quantamagazine –

Lineweaver, C. H. (2013). The entropy of the universe and the maximum entropy production principle. In Beyond the Second Law: Entropy Production and Non-equilibrium Systems (pp. 415-427). Berlin, Heidelberg: Springer Berlin Heidelberg. –

Bekenstein, J.D. (1972). Black holes and the second law. Lett. Nuovo Cimento 4, 737–740. –

Carroll, S.M. (2022). The Biggest Ideas in the Universe: Space, Time, and Motion. Penguin Publishing Group. –

Black hole thermodynamics, Wikipedia –

Cosmology and the arrow of time: Sean Carroll at TEDxCaltech, TEDx Talks via YouTube –

Carroll, S. M. (2008). The cosmic origins of time’s arrow. Scientific American, 298(6), 48-57. –

The Passage of Time and the Meaning of Life | Sean Carroll (Talk + Q&A), Long Now Foundation via YouTube –

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Written by Casper Mebius, Derek Muller & Petr Lebedev
Edited by Trenton Oliver & Jamie MacLeod
Animated by Mike Radjabov, Ivy Tello, Fabio Albertelli and Jakub Misiek
Filmed by Derek Muller, Albert Leung & Raquel Nuno
Molecular collisions video by CSIRO’s Data61 via YouTube: Simulation of air
Additional video/photos supplied by Getty Images, Pond5 and by courtesy of NASA, NASA’s Goddard Space Flight Center, NASA Goddard Flight Lab/ CI Lab, NASA/SDO and the AIA, EVE, HMI, and WMAP science teams. As well as the Advanced Visualization Laboratory at the National Center for Supercomputing Applications, B. Robertson, L. Hernquist
Music from Epidemic Sound & Jonny Hyman
Produced by Derek Muller, Petr Lebedev, Emily Zhang, & Casper Mebius

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38 Responses

  1. Steve Mould says:

    The thing about one photon from the sun turning into several spreading out in all directions answered a long standing question for me – how to explain the way the sun “powers” life on earth in terms of entropy. Thanks!

    • Ise River says:

      No one taught you about photosynthesis?

    • Captain Ace says:

      If watching a Veritasium video leads to me watching a SteveMould video with black holes instead of another Veritasium video with black holes; could that be considered a Spool Paradox or another example of a big photon converting into many small photons?

      Jokes aside, I love your videos and I lm glad you left a comment.

    • wantstocomment says:

      It’s just life radiation bro.

    • Garry Sekelli says:

      One photon cannot turn into several photons. İmo.

    • Nikhil Pratap Singh 20 BHP 21 says:

      ​@Garry Sekelliwhy not? If a high energy photon is absorbed, cant it can be later emitted in different levels? In a way that all the photons’ energy when aaded up will be equal to the original high energy photon

  2. JojohGaming says:

    This man never stops to amaze me, to have not only the capacity to have this broad understanding of the physical world, but also have the social and verbal skills to be a grasping storyteller. I’ve been following you for years and you sir, are a modern day hero and nothing less. Well done!

  3. Abhinav Rastogi says:

    Thank you for everything that you do. The part about time ceasing to exist at the heat death of the universe was mind-blowing.

  4. Cachor says:

    It took me years to wrap my head around the concept of Entropy.

    What helped me the most was studying the history of the concept.

    This video is an accurate summary of what entropy is.

    • Which Film is It says:


    • Gave says:

      I still dont understand it lol

    • Darman Beskar says:

      ​@GaveI have an engineering degree with 6 thermodynamics classes under my belt, an IQ of 138 and I have been studying thermodynamics since the age of 15.

      In the words of my thermodynamics professor, anyone who thinks they fully understand entropy doesn’t. That is true of thermodynamics in general. You can always dig deeper.

    • Greco Cabanero says:

      ​@Gavehow not? Or which part?

    • Dileep Kumar says:

      ​@Darman Beskarif u have 138 iq, then u will observe and decide u won’t believe those sentences blindly lol

  5. Thetarget1 says:

    This video is a masterpiece. It´s by far the best explanation of entropy I´ve seen on youtube, going through the most important concepts in several semesters of physics, and it explains it both in simple layman´s terms, but also through the relevant equations, while giving them a graphical representation. It´s honestly really impressive science communication. And I love the old school Veritaseum interviews of random people, who express our own questions and confusion. Well done!

    • feynman says:

      Are you a physicist?
      This type of video serve no educational purpose whatsoever. They are a kinda Schaum’s Outline book: they are too easy for someone who already knows the topic very well, and too complex for those who have zero understanding or little knowledge of the subject.

    • Ivo Kal says:

      ​@feynmanbut just right for those who know a little bit and are looking to learn more.

    • Kitsune Chan says:

      I remember learning about entropy in middle school. I had no idea what it is. Why is “chaos” a thing in physics. This video actually explained it to me.

    • feynman says:

      @Ivo Kal No. As i said, Derek’s videos serve ONLY the purpose to INDUCE the interested person into picking up the book and deepen the subject. They have no educational purpose whatsoever. What do I mean by, “educational”? Educating involves reading, studying a theorem, a lor aw, a subject, being able to talk and explain to other peers, and being able to apply the theory to solve practical problems. Education encompasses these activities.
      These videos’ purpose is not educational. They aim at triggering off curiosity, that’s all. Even those who know little about the topic wouldn’t be able to use this video’s knowledge practically or even to explain what entropy is. They couldn’t recognize the concept of “entropy”, which it’s possible only if you STUDY.

    • feynman says:

      ​@Kitsune Chan Don’t let yourself be deceived by “impression” or the video’s animations. “Explaining” something has no scientific value because you’re not using any indicator that measures your actual comprehension. Understanding a concept involves being able to recognize it in different contexts; being able to use it.
      This is the dark side of popular scientific books/videos: they lead people into erroneously thinking they know something when actually they haven’t. Popular scientific books and videos are nothing else but teasers.
      One of the negative sides is represented by animations that hypnotize the majority of people who get so fascinated that they fail to discern between real comprehension and just admiration. Grant Sanderson (3blue1brown) is a magician in this sense. People watch his videos even though they have zero understanding. And many others mistake this admiration as “comprehension”. Don’t make this same mistake. Remember: comprehension must be measured scientifically. Not through the SENSATIONS.

  6. Dante Gabriel2005 says:

    I’m a chemist, and this surprisingly reminds me of the balance we do in chemical formulas, the universe is trying to reach thermal equilibrium.

  7. NightHawkInLight says:

    I told my brother that if he applied to be one of your physics writers that he should tell you that I miss your street interview videos. Looks like you already had my wish on your radar!

    • TechSquidTV says:

      I really miss those too

    • Cuthbert Allgood says:

      No offense to anyone who likes them, but I was actually thinking that they’re just a waste of time. Like, I’m curious what Veritasium has to say on the subject, so what’s interesting about what random people think about it? They don’t really contribute anything to the video.

    • BeaT BoX says:

      ​@Cuthbert Allgoodhm.

    • Henil Malaviya says:

      @Cuthbert Allgood those short public interviews arises common misconception in viewer’s mind, which is extremely important when it comes to learning via media.

    • TechSquidTV says:

      @Cuthbert Allgood no that’s fair, but I do like seeing what “normal” people think. It’s a good refresher into what the average person believes or thinks.

  8. zephh says:

    I know nothing about physics but I feel like this video was just spectacular. The writing, the segments, the positive message at the end. Another masterpiece.

  9. Haider Abbas says:

    In this age of short form content, it is really an amazing feat to make people glued to the screen for all twenty seven minutes. I have always admired your story telling, how you develop a question and then proceed to answer it in the most prolific way is awesome. I have been studying physics for quite sometime now this is the best explanation of entropy. I especially enjoyed the part where you explain why it only tends to increase, it’s relation with the arrow of time. Best video. I’m always waiting for this kind of content.

    • Yunus Emre Tortamis says:

      In the age of “short form content”, if there is going to be periodization for today’s world, that’s the way to put it

  10. Nachiket Shelar says:

    Its been quite a time since high school, we came across this concept of Entropy and I was always fascinated by it, because it somehow had all the answers. It says “Entropy of a system always increases in a chemical reaction” was such a strong sentence, it still gives me goosebumps. Beautiful video, hope new science students get inspired by you.

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