Overview
Derek Muller opens with street interviews asking a deceptively simple question: what does the earth get from the sun, and how much does it radiate back into space. Almost nobody answers correctly, which sets up the video's real subject, a concept most people encounter in school but never actually understand: entropy.
The video traces entropy's origin back to 1824, when Sadi Carnot, a young French military engineer, set out to understand why French steam engines were falling behind British designs. Carnot modeled an idealized, fully reversible heat engine and showed that its efficiency depends only on the temperature difference between its hot and cold sides, not on the materials or design. This insight led to the idea of absolute zero and the Kelvin scale, and it proved that no heat engine, however well built, can ever be 100 percent efficient, because some heat must always be dumped into the cold side to reset the cycle.
Decades later, Rudolf Clausius named this unrecoverable, spread-out energy "entropy" and formalized the first two laws of thermodynamics: energy in the universe is constant, and entropy in the universe tends toward a maximum. Ludwig Boltzmann then explained why, using statistics. With a simple model of energy packets bouncing between hot and cold metal bars, he showed that heat flowing from cold to hot is not physically impossible, it is simply so improbable at the scale of real numbers of atoms that it is never observed. The video's Rubik's cube analogy makes this concrete: there is one solved state and quintillions of scrambled ones, so random moves overwhelmingly tend toward disorder.
The second half of the video applies this framework to life, the sun, and the cosmos. Life persists locally against entropy only because earth is not a closed system, it receives concentrated, low entropy energy from the sun and radiates twenty times as many, lower energy photons back into space, increasing total entropy the whole time. The video cites Jeremy England's dissipative adaptation research as a physical explanation for why life may be an inevitable consequence of matter dissipating energy efficiently. It closes on the cosmic scale, covering the low entropy Big Bang (the "past hypothesis"), Bekenstein and Hawking's discovery that black holes hold the overwhelming majority of the universe's entropy, and the eventual heat death of the universe when entropy reaches maximum and nothing further can happen.
This video is one of the clearest existing explanations of a concept that gets taught poorly almost everywhere else. Most people leave school with "entropy equals disorder" as their only mental model, which is both vague and frequently misleading. The historical, statistical framing here (Carnot's engines, Boltzmann's probability argument, the Rubik's cube analogy) gives a durable, teachable version of the idea that holds up under scrutiny and translates well into original explainer content.
The underlying pattern, that irreversibility is a statistical near-certainty rather than an absolute law, and that local order can only be purchased with a larger increase in entropy somewhere else, is a mental model with reach well beyond physics. It shows up in systems thinking, in the honest limits of any process or funnel (nothing converts 100 percent of its input into useful output), and in how to reason about "impossible" versus "vanishingly unlikely" outcomes in general.
As a source, it also functions as a well-researched jumping off point for original content: the Carnot efficiency ceiling, the sun as a low entropy energy source, and the heat death framing are each strong enough to carry a standalone explainer, newsletter segment, or short-form piece on their own.
Key Points
- The earth radiates essentially the same amount of energy back into space that it receives from the sun, but as far more, lower quality photons, which is where entropy enters the picture.
- Sadi Carnot's 1824 analysis of an idealized, fully reversible heat engine showed that efficiency depends only on the temperature difference between the hot and cold sides, not on the engine's design or materials.
- Carnot's work implies a lowest possible temperature, absolute zero, and forms the theoretical basis of the Kelvin scale.
- No real heat engine can be 100 percent efficient, because completing the cycle requires dumping some heat into the cold side rather than converting it all into work.
- Rudolf Clausius named this unrecoverable, spread-out energy "entropy" and stated the first two laws of thermodynamics: total energy is constant, and entropy tends toward a maximum.
- Ludwig Boltzmann showed statistically that heat flowing from cold to hot is not impossible, only astronomically improbable once the number of particles involved is large.
- The Rubik's cube analogy illustrates why: there is one solved configuration, a few nearly solved ones, and an overwhelming number of scrambled ones, so random change trends toward disorder.
- Life does not violate the second law because earth is not a closed system, it receives concentrated, low entropy energy from the sun and radiates roughly twenty times as many lower energy photons back into space.
- Physicist Jeremy England's dissipative adaptation research proposes that matter exposed to a sustained energy source will tend to organize into better and better energy dissipators, offering a physical account of why life may emerge.
- The universe's overall low starting entropy (the "past hypothesis") is explained by gravity, matter spread evenly through space is actually a low entropy state once gravity is accounted for.
- Jacob Bekenstein and Stephen Hawking showed that black holes carry entropy and temperature, and that black holes collectively hold the vast majority of all entropy in the universe.
- The arrow of time is fundamentally a consequence of entropy increase, and the universe is heading toward a "heat death" where energy is so completely spread out that no further events can occur.
Quotable
AI-generated from source material. Verify important details against the original source.
Derek Muller (Narration)
"When energy spreads out like this, it is impossible to get it back."
A single plain sentence that anchors the entire video's thesis on irreversibility.
Ludwig Boltzmann (via narration)
"Heat flowing from cold to hot is not impossible, it's just improbable."
Reframes the second law from an absolute prohibition into a matter of statistical likelihood, the central reframe of the whole video.
Derek Muller (Narration)
"Every turn moves the Rubik's cube further from being solved, from a less likely state to a more likely state, a total mess."
Turns an abstract statistical concept into something immediately intuitive using a familiar object.
Jeremy England (paraphrased in video)
"You start with a random clump of atoms, bang on it for long enough, and you get a plant."
Compresses an entire theory of the physical origin of life into one memorable, almost absurd sounding line.
Derek Muller (Narration)
"We never see an asteroid uncrash or a planetary system unmix."
Vivid, concrete "un-events" make the one-way direction of entropy viscerally obvious.
Concepts
Historical Origins
Sadi Carnot and the Search for Engine Efficiency
In 1824, 17 year old Sadi Carnot, son of a Napoleonic general, set out to understand why French steam engines lagged behind British ones, converting only around 3 percent of thermal energy into useful work. His analysis, aimed at practical military and industrial advantage, ended up establishing the theoretical limits of all heat engines and laying the foundation for thermodynamics as a field.
The Carnot Cycle (Ideal Heat Engine)
Carnot modeled a fully reversible engine: a gas chamber alternately placed in contact with a hot bar and a cold bar, with a piston driving a flywheel. Because every step can be run in reverse and returned exactly to its starting state, the cycle is thermodynamically ideal, the theoretical best case against which real engines are measured.
Carnot Efficiency and the Kelvin Scale
Carnot showed efficiency depends only on the ratio of the cold and hot temperatures, not on the working substance or engine design. Pushed to its logical extreme, this implies a coldest possible temperature at which a gas would exert no pressure at all, absolute zero, which became the zero point of the Kelvin scale.
The Birth of Entropy
Rudolf Clausius and the Naming of Entropy
Decades after Carnot, Clausius formalized why even an ideal reversible engine cannot be 100 percent efficient in practice: friction and heat loss to the environment mean less energy ends up doing useful work. He named the measure of this increasingly spread out, less usable energy "entropy."
The First and Second Laws of Thermodynamics
Clausius's formulation gives the two laws in their simplest form: the total energy of the universe is constant (first law), and the entropy of the universe tends toward a maximum (second law). Energy is never destroyed, but it becomes progressively less available to do useful work.
Entropy as Energy Dispersal, Not Just Disorder
The common shorthand "entropy is disorder" is imprecise. The more accurate framing used throughout the video is that entropy measures how spread out or dispersed energy has become. Concentrated energy in a hot bar is low entropy, energy leaked into the walls and environment is high entropy, even though the total amount of energy has not changed.
The Statistical View
Boltzmann's Statistical Insight
Ludwig Boltzmann modeled heat as discrete energy packets randomly distributed among atoms in two touching metal bars. Heat flowing from cold to hot corresponds to a real, countable configuration, it is not forbidden, it is just one of an astronomically small fraction of all possible configurations, so it essentially never happens once you're dealing with realistic numbers of atoms.
The Rubik's Cube Analogy for Probability
A solved Rubik's cube has exactly one solved state, a handful of nearly solved states, and quintillions of scrambled ones. Random turns overwhelmingly tend to move the cube away from order, not because order is forbidden, but because it is a vanishingly small target among all possible configurations. This is a direct, intuitive stand-in for why entropy increases.
Why Entropy Increases: A Matter of Scale
With only a handful of atoms, unlikely low entropy events (like heat flowing briefly from cold to hot) happen with real, calculable frequency. As the number of particles scales toward the trillions involved in everyday objects, those probabilities collapse toward zero, which is why the second law appears to be an absolute rule in ordinary experience even though it is fundamentally statistical.
Life and Entropy
How Life Locally Decreases Entropy
A refrigerator, a house being heated, or a living organism all appear to locally decrease entropy, but this is only possible because a much larger increase in entropy is happening elsewhere, at the power plant burning coal, or in the sun's fusion reactions. Local order is always purchased with a bigger entropy bill paid somewhere else in the system.
The Sun as a Source of Low Entropy
Earth is not a closed system. It receives a steady stream of concentrated, low entropy energy from the sun, and radiates back roughly twenty times as many photons at lower energy each. Plants, animals, and every biological process on earth are, from a thermodynamic standpoint, machinery for converting that concentrated solar energy into a more spread out form, increasing entropy the entire time.
Dissipative Adaptation and the Physical Origin of Life (Jeremy England)
Physicist Jeremy England's research proposes that matter exposed to a sustained, driving source of energy will tend, over time, to self-organize into structures that are increasingly efficient at dissipating that energy. Life, in this view, is not an improbable exception to the second law, but potentially one of its natural, favored outcomes.
Cosmic Scale
The Past Hypothesis and the Low-Entropy Big Bang
Since entropy has been rising ever since, the universe must have started in an extremely low entropy state at the Big Bang, known as the past hypothesis. The early universe looked almost perfectly uniform, which seems high entropy until gravity is factored in. Because gravity pulls matter together, a perfectly even spread of matter is actually a very unlikely, low entropy starting condition.
Black Holes as the Universe's Largest Entropy Reservoirs
Jacob Bekenstein proposed in 1972 that black holes carry entropy proportional to their surface area, which implied they must also have a temperature and therefore emit radiation. Stephen Hawking later proved this mathematically, now known as Hawking radiation. Black holes turn out to hold the overwhelming majority of all entropy in the observable universe, dwarfing stars, galaxies, and the cosmic microwave background combined.
The Arrow of Time and the Heat Death of the Universe
Because entropy only increases, it gives time a direction, we never observe an asteroid uncrashing or a planetary system unmixing. Extrapolated far enough into the future (beyond 10 to the 100 years, after even black holes have evaporated), the universe reaches its most probable state, energy completely and evenly spread out, a condition known as heat death, where no further meaningful events can occur.
Implementation
AI-generated from source material. Verify important details against the original source.
Use the statistical reframe when explaining "impossible" outcomes
When writing or scripting content that explains why some outcome basically never happens, borrow Boltzmann's framing: it isn't forbidden, it's just improbable at scale. This is a stronger, more accurate hook than a flat "it can't happen."
Apply the Carnot efficiency ceiling as a mental model
No real process converts all of its input into useful output, some loss to the environment is unavoidable. Use this as a sanity check against overly optimistic assumptions in funnels, conversion rates, or ROI projections.
Reuse the Rubik's cube analogy for teaching complex systems
When explaining why systems drift toward disorder without ongoing maintenance or energy input, the Rubik's cube framing (one solved state, quintillions of scrambled ones) is an effective, reusable teaching device for a newsletter or video script.
Treat "low entropy input" as a sourcing principle
In content or resource work, identify where concentrated, high quality input (capital, attention, raw material, a strong lead) is coming from before evaluating downstream output, mirroring how the sun's concentrated energy underwrites everything that happens on earth.
Build a standalone short-form piece around the second law
The closing tea-and-milk complexity framing (low entropy is uninteresting, maximum entropy is uninteresting, complexity peaks in between) is strong enough on its own to carry a short social post or newsletter segment without needing the full video.
Cross-link future science pages back to this one
As the new Science category grows in the repository, link related pages (thermodynamics, cosmology, statistical mechanics) back to this page so it functions as an anchor reference for the entropy framework.
Use the AI Prompt tab to develop follow-up explainer material
Load the AI Implementation Prompt in a fresh AI session to draft additional explainer scripts, quiz questions, or content angles built on this entropy framework without re-reading the full source.
Tools & Resources
The original video description linked each source below through shortened ve42.co redirect links that were truncated in the source material and could not be verified. Titles and authors are preserved from the description, search for the title directly to locate the current source.
| Resource | Description |
|---|---|
| Carnot (1824) | "Reflections on the Motive Power of Heat," Carnot's original essay on heat engines, the foundational source for the video. |
| Steve Mould, "A Better Description of Entropy" | YouTube video referenced as a complementary explanation of entropy. |
| Dugdale (1996) | "Entropy and Its Physical Meaning," academic reference text cited in the video's research. |
| Schroeder (1999) | "An Introduction to Thermal Physics," standard thermodynamics textbook cited as a reference. |
| Fowler, "Heat Engines: The Carnot Cycle" | University of Virginia lecture notes on the Carnot cycle. |
| Clausius (1867) | "The Mechanical Theory of Heat," Clausius's original text naming and formalizing entropy. |
| England (2013, 2015) | Jeremy England's papers on the statistical physics of self-replication and dissipative adaptation, the basis for the video's life-and-entropy segment. |
| Wolchover, "A New Physics Theory of Life" | Quanta Magazine profile of Jeremy England's work, cited as further reading. |
| Brilliant.org | Video sponsor, interactive courses in math, science, and programming. Link confirmed live. |
Suggested Resources
| Resource | Description |
|---|---|
| Sean Carroll, "The Big Picture" | Extends the past hypothesis and cosmological entropy discussion into a full treatment of meaning and physics. |
| Brian Greene, "Until the End of Time" | Covers entropy, the arrow of time, and the far future of the universe in more depth than the video allows. |
| PBS Space Time (YouTube) | Deeper technical dives on black hole thermodynamics and the arrow of time for viewers who want to go beyond the Veritasium explainer level. |
| Carlo Rovelli, "Seven Brief Lessons on Physics" | Short, accessible companion covering thermodynamics and time alongside broader modern physics, useful for further content development. |
Source Material
Original source attribution, metadata, and publication details are available in the Overview tab. This source material originates from a video transcript. Transcription, formatting, or extraction errors may exist. Verify against the original source before republishing or relying upon the material.
[00:00]
One of the most important, concepts in all of physics. From molecular collisions to humongous storms. From the beginning of the universe to its inevitable end. The direction of time and even be the reason that life exists. To see the confusion around this topic, you need to ask only one simple question. What does the Earth get from the sun? "What does the earth get from sun?" "Well, it's light rays?" "Heat." "Warmth." "Warmth, light." "Vitamin D, we get vitamin D from the ultraviolet rays." "Well, a lot of energy." "Get from this, energy?" "Yeah, energy." "Energy." "Nailed it." A certain amount of energy from the sun.
[01:00]
Does the earth radiate back into space relative to that amount that it gets from the sun? "Probably not as much, I, you know, radiating right back." "I'd say less." "Less." "I say less." "I guess about 70%?" "It is a fraction." "I'd say 20%." "Because we use some of it." "We consume a lot, right?" It never really goes away. You can't really use it up. Break even, wouldn't it? Same amount, yeah. "You know, cause and effect. It'd be equal in some ways, right?" For most of the earth's history, same amount of energy radiates into space. "Wow." Because if we didn't do that, hotter, that'd be a problem. "That'd be a big problem." So, if that is the case. "Yeah." Getting from the sun? "That's a good question." "Hmm." It gives us a nice tan.
[02:01]
"It gives us a nice tan, I love it." Special from the sun, we get without the energy? But nobody talks about it. To go back to a discovery made two centuries ago. France was being invaded, Prussia, and Russia. The son of one of Napoleon's generals was Sadi Carnot, a 17-year-old student. Writes a letter to Napoleon to request to join in the fight. Battle, never replies. Wish a few months later when Paris is attacked, just east of the city, for the advancing armies, only a day of fighting. Forced to retreat, Carnot is devastated. Goes to visit his father after Napoleon's downfall.
[03:02]
General, but also a physicist. He wrote an essay on how energy in mechanical systems. Visit, they talk at length of the time, steam engines, being used to power ships, mine ore, and excavate ports. The future industrial and military might of nations depended on having the best steam engines. But French designs were falling behind those of other countries like Britain. Himself to figure out why. At the time, even the best steam engines only converted around 3% of thermal energy into useful work. That, he could give France its place in the world. Years studying heat engines.
[04:03]
And one of his key insights, heat engine would work, losses to the environment. It looks something like this. Bars, one hot and one cold. Chamber filled with air, or out through the bottom. Inside the chamber is a piston, which is connected to a flywheel. Temperature just below that of the hot bar. Is brought into contact with the chamber, with heat flowing into it to maintain its temperature. Up, turning the flywheel. Next, the hot bar is removed, continues to expand, the temperature decreases. In the ideal case, of the cold bar.
[05:04]
And the flywheel pushes the piston down. And as the air is compressed, heat is transferred into the cold bar. The cold bar is removed. The flywheel compresses the gas further until it is just below that of the hot bar, again and the cycle repeats, from the hot bar is converted into the energy of the flywheel. About Carnot's ideal engine is that it is completely reversible. If you ran the engine in reverse, lowering the temperature, into contact with the cold bar, in heat from the cold bar, increasing its temperature. On top of the hot bar is used to return the heat back into the hot bar.
[06:00]
In the forward direction, in reverse, and at the end, to its original state of energy required, nothing really changes. You can always undo what you did. So what is the efficiency of this engine? Since it's fully reversible, efficiency to be 100%, but that is not the case. Of the flywheel increases by the amount of heat flowing into the chamber from the hot bar, the chamber at the cold bar. We divide this energy by the heat input from the hot bar. Side is equal to the work done by the gas on the piston, greater than the work done by the piston on the gas on the cold side.
[07:01]
Which equals the heat out. And this is because on the hot side, the hot gas exerts a greater pressure same gas when cold. To increase the efficiency of the engine, temperature of the hot side, of the cold side, or both. Carnot's ideal heat engine and realizes it could form the basis for an absolute temperature scale. To expand an extreme amount, so much that it cools to the point effectively stop moving. Pressure on the piston, and it would take no work to compress it, no heat would be lost. This is the idea of absolute zero, 100% efficient engine. Scale, the Kelvin scale.
[08:00]
Amount of heat in and out hot and cold side respectively, because they are directly proportional. So we can express efficiency like this, which we can rewrite like this. Is that the efficiency doesn't depend on the materials or the design of the engine, but fundamentally on the temperatures of the hot and cold sides. You'd need infinite temperature zero on the cold side, both of which are impossible in practice, losses to the environment, heat engine 100% efficient. And that's because to return the piston to its original position, you need to dump heat into the cold bar. Stays in the flywheel. High pressure steam engines up to 160 degrees Celsius. Maximum efficiency was 32%.
[09:02]
Was more like 3%. Experience friction, dissipate heat to the environment, at constant temperatures. So for just as much heat going in, less energy ends up in the flywheel, the walls of the cylinder, the axle of the flywheel, and is radiated out into the environment. When energy spreads out like this, it is impossible to get it back. So this process is irreversible. The total amount of energy didn't change, but it became less usable. When it is concentrated and less usable when it's spread out. Physicist, Rudolf Clausius, and he comes up with a way to measure how spread out the energy is. He calls this quantity, entropy.
[10:02]
Concentrated in the hot bar, that is low entropy, to the surroundings, the walls of the chamber and the axle will entropy increases. Of energy is present, but in this more dispersed form, it is less available to do work. The first two laws of thermodynamics like this. Universe is constant. Universe tends to a maximum. Spreads out over time, many phenomena in the world. Down and cool things heat up, why gas expands to fill a container, perpetual motion machine, energy in a closed system.
[11:00]
Is always decreasing. Entropy is as disorder, it is associated with things random, and less ordered. To think about entropy energy to spread out. So why does energy spread out over time? I mean, most of the laws of physics forwards or backwards in time. Time dependence arise? Well, let's consider two small metal bars, one hot and one cold. For this simple model, we'll consider only eight atoms per bar. Each atom vibrates according to the number of energy packets it has. The more packets, the more it vibrates. Seven packets of energy in the left bar and three in the right. The number of energy packets in each bar is what we'll call a state. First, let's consider just the left bar.
[12:01]
It has seven energy packets, which are free to move around the lattice. This happens nonstop, randomly from atom to atom giving different configurations of energy, the same the whole time. Now, let's bring the cold bar back in and touch them together. The energy packets can now hop around different configurations, is equally likely. Snapshot at one instant in time and see where all the energy packets are? So stop, look at this. Packets in the left bar, and only one in the right bar. So heat has flowed from cold to hot. Because it decreases entropy? Well, this is where Ludwig Boltzmann made an important insight. To hot is not impossible.
[13:01]
It's just improbable. There are 91,520 configurations with nine energy packets in the left bar, energy packets in each bar. That is the energy is more than six times spread between the bars. But if you add up all the possibilities, 10.5% chance that the left bar packets than it started. This happening around us? Increase the number of atoms energy packets to 100, and 30 in the right. Chance that the left solid ends up hotter than it started. We keep scaling up the system, are around 100 trillion, more energy packets.
[14:02]
To hot is just so unlikely that it never happens. Think of it like this, Rubik's cube. Right now, it is completely solved, and make some turns at random. Will get further and further from being solved. That I'm really messing this cube up? One way for it to be solved, a few ways for it to be almost solved, and quintillions of ways for it to be almost entirely random. Without thought and effort, every turn moves the Rubik's cube that of it being solved to a more likely state, a total mess. Of energy is to spread out and for things to get messier, then how is it possible to have something the cold interior of a house.
[15:01]
Exterior gets hotter? Energy is going from cold to hot, decreasing the entropy of the house. Entropy is only possible greater amount somewhere else. In this case, at a power plant, and coal is being released, plant in its environment, the electric generators, the way to the house, in the fans and compressor. Is achieved at the house increase in entropy required to make that happen. Constantly increasing accelerates that increase, structure left on earth? Separate from cold parts?
[16:01]
How does life exist? Well, if the earth were a closed system, the energy would spread out completely, meaning, all life would cease, everything would decay and mix, the same temperature. But luckily, earth is not a closed system, because we have the sun. Us is a steady stream concentrated bundled up energy. From the sun is more useful than the energy we give back, more clumped together. Energy and use it to grow and create sugars, and use that energy to maintain their bodies and move around. Bigger animals get their energy by eating smaller animals and so on. And each step of the way.
[17:00]
The energy becomes more spread out. "Okay, interesting." "Yeah." "Oh wow, I did not know that." "There you go." That reaches earth from the sun is converted into thermal energy, and then it's radiated back into space. But in fact, it's the same amount. "You do know this is." "I'm a PhD physicist." "I trust you." The increase in entropy can be seen of photons arriving at and leaving the earth. For each photon received from the sun, 20 photons are emitted, and everything that happens on earth, falling, herds stampeding, hurricanes and tornadoes, people eating, sleeping, and breathing. Process of converting fewer, higher energy photons lower energy photons.
[18:01]
Without a source of concentrated energy the spread out energy, life on earth would not be possible. Suggested that life itself second law of thermodynamics. Toward maximum entropy, accelerate that natural tendency, because life is spectacularly good into high entropy. Layer of seawater produces entropy when cyanobacteria present than when it's not. This one step further, there is a constant stream could favor structures that dissipate that energy. And over time, this results in better and better energy dissipators, eventually resulting in life.
[19:00]
Or in his own words, "You start with a random clump of atoms, bang on it for long enough, that you get a plant." The low entropy from the sun, sun get its low entropy? The answer is the universe. Entropy of the universe it was lower entropy yesterday the day before that, back to the Big Bang. So right after the Big Bang, that is when the entropy was lowest. This is known as the past hypothesis. The entropy was low, that way for the universe to unfold as it has. But the early universe was hot, dense, and almost completely uniform. Mixed and the temperature was basically the same everywhere.
[20:01]
Varying by at most 0.001%. So how is this low entropy? Well, the thing we've left out is gravity. Gravity tends to clump matter together. So taking gravity into account, having matter all spread out like this, would be an extremely unlikely state, and that is why it's low entropy. Expanded and cooled, together in more dense regions. Amounts of potential energy were turned into kinetic energy. And this energy could also be used downhill can power a turbine. Started hitting each other, was converted into heat. So the amount of useful energy decreased. Thereby, increasing entropy. Over time, the useful energy was used.
[21:01]
Galaxies, and life were formed, increasing entropy all along. The universe started with around 10 constants worth of entropy. In the observable universe have about 9.5 times 10 to the 80. Intergalactic medium combined have almost 10 times more, of the early universe. A lot more is contained in neutrinos cosmic microwave background. In 1972, Jacob Bekenstein proposed another source of entropy, black holes. Entropy of a black hole to its surface area, its entropy increases. The idea was nonsense and for good reason. According to classical thermodynamics.
[22:01]
If black holes have entropy, then they should also have a temperature. They should emit radiation and not be black after all. To prove Bekenstein wrong was Stephen Hawking. Results showed that black holes known as Hawking radiation, and they do have a temperature. Center of the Milky Way hundred trillionth of a Kelvin, is far too weak to detect. So still pretty black. Black holes have entropy and Bekenstein was right. Bekenstein's proposal much entropy they have. At the center of the Milky Way Boltzmann constants of entropy. That is 1,000 times as much as the early observable universe.
[23:00]
The other particles combined. And that is just one black hole. Account for 3 times 10 constants worth of entropy. So almost all the entropy of the universe is tied up in black holes. That means, the early universe of the entropy it has now. And everything that happens planetary systems forming, galaxies merging, asteroids crashing, stars dying, to life itself flourishing, all of that can happen because the entropy and it has been increasing, and it all happens only in one direction. We never see an asteroid uncrash or a planetary system unmix and gas that made it up.
[24:00]
Between going to the past difference comes from entropy. The fact that we are going from unlikely there is an arrow of time. Continue until eventually, the energy gets spread out so completely will ever happen again. This is the heat death of the universe. In the distant future, more than 10 to the 100 years from now, after the last black hole has evaporated, its most probable state. You would not be able to tell moving forwards or backwards, itself would disappear. Is this awful thing that leads us inevitably towards the dullest outcome imaginable.
[25:00]
Entropy has low complexity has maximum complexity. It's actually more like this, tea and milk. Is not very interesting. In, the two start to mix and these beautiful patterns emerge. And before you know it, they're gone, back to being featureless. Are low in complexity, where complex structures appear and thrive. And since that's where we find ourselves, entropy we've got while we can. Understand just about anything, from a cup of tea cooling down to the evolution of the entire universe. For a free and easy way to add powerful tools to your arsenal, then you should check out.
[26:00]
This video sponsor, brilliant.org. Key concepts in everything to programming and physics. All you need to do is set your goal, perfect learning path for you, tools you need to reach it. Think like a programmer? Course, "Thinking in Code" is a fast and easy way to get there. Using an intuitive drag and drop editor, really need to know, like nesting and conditionals. Right in to program a robot and then learn how to apply your new tools to your everyday life, like automating reminders on your phone your matches on a dating app. Is that they connect what you learn to real world examples. And because each lesson is hands-on, you'll build real intuition, learned to good use. Brilliant has to offer free brilliant.org/veritasium.
[27:00]
Down in the description. First 200 of you to sign up annual premium subscription. For sponsoring this video, and I wanna thank you for watching.
AI Prompt
AI-generated from source material. Verify important details against the original source.
AI Implementation Prompt
CONTEXT This prompt is built from "The Most Misunderstood Concept in Physics," a Veritasium video by Derek Muller (published July 1, 2023) explaining entropy. The video traces entropy from Sadi Carnot's 1824 analysis of steam engine efficiency, through Rudolf Clausius naming entropy and stating the first two laws of thermodynamics, through Ludwig Boltzmann's statistical explanation of why entropy increases, to the role of entropy in life, the low entropy Big Bang, black holes, and the eventual heat death of the universe. The core thesis: entropy is not simply "disorder," it is a measure of how spread out energy has become, and the second law of thermodynamics is fundamentally statistical rather than absolute, events that decrease entropy are not impossible, only vanishingly improbable at real world scales. KEY PRINCIPLES 1. Entropy measures how spread out or dispersed energy has become, not disorder in a loose everyday sense. 2. No real heat engine can be 100 percent efficient, some heat must always be dumped to complete the cycle (Carnot). 3. Total energy in the universe is constant, entropy in the universe tends toward a maximum (first and second laws). 4. Entropy increase is statistical, not absolute, low entropy events are improbable, not impossible (Boltzmann). 5. Probability of entropy decreasing collapses toward zero as the number of particles in a system grows. 6. Local decreases in entropy (life, refrigeration, heating a house) are only possible because a larger entropy increase happens elsewhere in the system. 7. Earth is not a closed system, it receives low entropy energy from the sun and radiates a larger number of lower energy photons back into space. 8. A low starting entropy for the universe (the past hypothesis) is explained once gravity is factored into what counts as "spread out." 9. Black holes hold the overwhelming majority of entropy in the observable universe. 10. Entropy increase gives time its direction, the arrow of time is a consequence of the second law. KEY LEVERS For explaining or applying this material, the primary leverage points are: the historical narrative (Carnot's engine problem) as a hook, the statistical reframe (improbable, not impossible) as the core insight, concrete physical analogies (the Rubik's cube, tea and milk) for building intuition, and the sun-to-earth energy flow as the bridge from abstract physics to everyday relevance. WHAT THIS IS NOT This is not a simple "entropy equals disorder" explainer, that shorthand is imprecise and the source explicitly moves past it. This is not a claim that life violates the second law, life is fully consistent with it once the whole system (including the sun) is considered. This is not a proof that entropy decrease is impossible, the source is explicit that it is a matter of overwhelming improbability, not a hard prohibition. This is not primarily a cosmology lecture, the black hole and heat death material serves the broader point about the direction of entropy, not a self-contained astrophysics deep dive. IMPLEMENTATION MODES 1. Teach: Explain any sub-concept (Carnot efficiency, Boltzmann statistics, black hole entropy, heat death) at a level appropriate for a specified audience. 2. Apply: Take the statistical reframe ("improbable, not impossible") and apply it to a non-physics domain the user specifies (business, systems, probability of an event). 3. Content Creation: Draft a script, newsletter segment, or social post built around one specific concept from this source (e.g., the Rubik's cube analogy, the sun as low entropy source). 4. Critique: Evaluate a piece of the user's own writing or explanation of entropy for accuracy against the source material. 5. Research Expansion: Identify related physics or cosmology topics (statistical mechanics, black hole thermodynamics, the past hypothesis) worth building into future Science category pages. 6. Analogy Building: Generate additional everyday analogies for entropy increase beyond the Rubik's cube and tea-and-milk examples already used in the source. 7. Quiz/Test Design: Build comprehension questions at a specified difficulty level to test understanding of entropy, the second law, or the statistical argument. 8. Decision Support: Help the user decide which piece of this material (historical, statistical, cosmological) best fits a specific content format or audience. AI OPERATING INSTRUCTIONS Stay grounded in the source material and the principles above rather than defaulting to generic physics textbook explanations. Favor the statistical, probability based framing over the vague "disorder" framing throughout. When the user's request strays from what the source actually supports, say so plainly rather than inventing detail. Ask clarifying questions when the user's goal or audience is unclear. Challenge inaccurate simplifications of entropy (e.g., "entropy always means things get worse") when they come up. Keep suggestions practical and tied to the source rather than offering generic motivational or unrelated physics content. GUIDED DISCOVERY Ask me up to three questions, one at a time, to determine: (1) what I am trying to accomplish, (2) which ideas from this source are most relevant to my situation, (3) how these concepts could be applied most effectively. Once you understand my situation, help me build a practical implementation plan.