Why is My Laptop On?

“Why is my laptop on?” does not seem like a complex question.

But when I tried to answer it this week—to really answer it—I realized that I only kind of understood energy pretty well.

And then I thought about you. And knowing you, you probably also only kind of understand energy pretty well.

So I took a deep breath, briefly questioned the point of my existence, and then dug into hours and hours of reading about energy. The end result is that now I’m someone who definitely understands energy maybe not really well but better than pretty well.

I learned a lot, but since I’m not really sure what you know and what you don’t know, I’ve done two things:

1) I’ve written a post here getting to the bottom of the question, “Why is my laptop on?” This is the main post.

2) I’ve written an add-on post called Energy for Dummies that goes through all the major kinds of energy in today’s world—coal, oil, natural gas, nuclear, biomass, hydroelectric, wind, solar, and geothermal—and explains what they are, how they work, and how big a role they play in things. If you’d like to brush up on your understanding of all that, check it out.


Okay, so why is my laptop on?

To answer this question sufficiently, I found a four-year-old boy on the street, offered him candy, kidnapped him, and now every time I think I have the answer to the question, he’ll ask “Why?”—because that’s what four-year-olds do—and that’ll force us to get to the real answer. We’ll call him George. Everyone say hi.

Little George

So my first answer to the question is, “Because I turned it on.”

George: Why?

Good question, George. I turned it on because I had to write this post. Well, no, actually I just said that—the truth is that my laptop is always on. I literally never turn it off.

George: Why?

Because modern laptops don’t really need to ever be turned off. And because I have a problem and I’m in love with my laptop.

George: Why?

Because I’m addicted to mental stimulation and I have no self-discipline.

George: Why?

Because I’m still in some weird rebellion against childhood authority even though I’m 32.

George: Why?

Because I’m just not that big a man.

George: Why?

Because I grew up in a world that bred softness into me. I’m a GYPSY.

George: Why?


What the fuck is going on? This isn’t at all what was supposed to be happening. This post is supposed to be about energy. Look, George, I need you to adjust your approach. I want you to not just ask “Why?” but to be more specific and make the questions energy-related. We’re trying to figure out how energy works.

George: Why?

Because that’s more interesting than exploring my personal shortcomings.

George: Why?

No. This isn’t working. I’m revising this drawing and making George six years old. I forgot what four-year-olds were like.

Okay he’s six now.

Big George

Let’s try again. My laptop is on because it has electricity running through it.

George: Why does the laptop have electricity running through it?

Because it’s plugged into a power cord, which is plugged into the wall socket.

George: Why does the wall socket have electricity in it?

Because it’s connected to New York City’s electrical grid.

George: Why does New York City have an electrical grid?

Okay, he’s actually brought up an interesting point here—let’s better understand this by taking a quick look at the history of humans using energy. You can divide this history into three general eras:

1. Energy in the really, really old days — doing hard things with your arms and being upset about it

Human energy

Pre-historic humans hadn’t really figured out how to do stuff.

2. Energy in the pretty old days — harnessing natural forces directly

Mechanical energy

At some point humans realized that they could outsource some of the hard labor by putting natural forces to work—a thrilling development. The earliest widespread example is the controlling of fire, which first happened between 125,000 and 400,000 years ago (depending on whom you ask). More recently, there’s ample evidence throughout the past 5,000 years of the use of windmills, dams, and other tools to convert natural forces into useful mechanical energy, and starting in the early 18th century, highly sophisticated technology like the steam engine to power ships and locomotives.

These are all examples of using the energy of natural forces directly—i.e. we learned all kinds of ways to harness natural energy, but that energy had to be used at the time and place of its harnessing. For example, a windmill in the old days would spin and that spinning force could be used to lift water or grind grain, but its limits would be whatever the physical spinning of the machinery could accomplish. Direct employment of energy is still common today—just think of everything that still works during a blackout. Your stove and heat (if they use gas), your toilet (which uses gravity to flush—just pour a bucket of water in), a wood fire or lit candle, your car—all examples of modern humans making energy straight from something in nature, with no middle man.

3. Energy in modern times — harnessing natural forces indirectly and at great scale

Electric energy

The world starkly changed about 100 years ago when humans learned to generate electricity and distribute it far and wide as controlled energy, through the electrical grid. It’s probably the single most impactful development in human history.

Suddenly, huge amounts of energy could be released on an industrial scale, converted into electricity, transported somewhere far away, and then converted into energy of almost any kind at the user’s convenience. A blazing hot coal fire on one side of a country could now be used to freeze ice on the other side. And a modern windmill can do a lot more than just lift or grind things—it can generate electricity, which can be used to do almost anything. My laptop works, and the energy it’s using might have originated with coal burning, atoms breaking, wind blowing, or rivers flowing—it doesn’t matter to me. All those natural forces look the same when they reach me—an outlet that pours electricity into whatever I plug into it.

In a way, electricity serves the world of energy like money serves the world of value:

Electricity is cash

So anyway, that’s why New York, and almost every city on Earth, has an electrical grid.

George: Why is there electricity in the electrical grid?

Because it’s connected to a power plant, which generates electricity and sends it into the grid.

George: How does the power plant make electricity?

Okay, this is a good time to mention the Law of Conservation of Energy, which states that energy can’t be created or destroyed, only converted into different forms. This means that humans can’t “make” energy, they can only harness existing forces and manipulate them into forms that suit them. So the only way to generate electrical energy is to convert some other existing source of energy into electricity.

In the case of a typical electricity-generating power plant, there are a few possibilities for the type of plant it is:

1) A type of renewable energy plant (i.e. hydroelectric, wind, solar, etc.). These sources make up a small minority of the world’s electricity—in the US, they account for about 11% of the electricity.

2) A nuclear power plant. Nuclear power makes up only 2.8% of the world’s energy, but actually represents a decent amount of the electricity in the US—about 21%.

3) A fossil fuel power plant. Almost 80% of the world’s total energy is sourced from fossil fuels—coal, oil, and natural gas—and fossil fuel power plants account for about 2/3 of the electricity in the US.

For this reason, I’m going to assume what the probability suggests—that the electricity in my laptop can be traced back to a fossil fuel power plant. And this applies to you too—no matter where you are in the world, whatever device you’re using to read this is probably able to be on because of a fossil fuel plant.

So back to George’s question—how does a fossil fuel plant make electricity?

It does so by burning a fossil fuel, which when it comes to electricity is either coal or natural gas (oil is used primarily as transportation fuel, not to generate electricity). Power plants burn coal or natural gas in order to boil large amounts of water and send steam roaring up into a turbine (a big propeller), causing it to spin. The turbine is connected to a shaft covered in coils of copper wires and surrounded by magnets. When the turbine spins, so do the copper coils, which shoot electrical currents down a wire, out of the power plant, and into the city’s grid as electricity.

So a burning fossil fuel, like coal, is what eventually led to the power in my laptop.

George: But you said energy can’t be created, only converted—so where did the energy come from that the coal released when it was burned?

Not bad for a six-year-old. So this leads to the question, “What are fossil fuels?”

Fossil fuels are made up of the remains of plants typically dating back to the Carboniferous Period, which took place between 300 and 360 million years ago, before even the dinosaurs were around.

Most plants, when they die, decompose, and any energy in them is released soon after their death. During the Carboniferous Period, though, many plants, algae, and microorganisms died in swamps or in the ocean, sunk to the bottom, and became buried in sand, clay, and other materials, retaining their energy along the way. Over millions of years, as more and more sand and rock piled on top of the dead organisms, the intense pressure eventually turned them into coal, oil, or natural gas. The energy that those ancient organisms died with is still there today in the form of chemical energy in the fossil fuels.

So it was the energy in those plants, living back then, that the power plant is releasing today through burning the fuel (combustion).

George: Are we gonna run out of fossil fuels?

Sorry George, you’ll have to read the other part of this post for that because I don’t want to write it twice.

George: Okay, but where did that energy come from? How did the energy get into those ancient plants in the first place?

The same way energy gets into plants today—photosynthesis.1

Photosynthesis is remarkably simple. Here’s how it works with a tree:

Sun shining on the tree breaks up the CO2, leaving carbon in the tree to make its substance and sending oxygen off as a byproduct. During this molecule breakup process, the tree absorbs energy from the sun (as chemical energy), which remains in the tree. When you burn a log, all you’re doing is reversing that process, returning the carbon and the oxygen back to each other and releasing the stored sun energy in the process, in the form of fire. Fire is the light and heat of the sun, absorbed into the wood for years, finally being released.

This is the same exact thing that’s happening when we burn fossil fuels—except unlike a log, fossil fuels absorbed the sun’s energy over 300 million years ago, so the energy that’s being released is ancient, 300 million year-old sunlight.

So my laptop and your device are being powered by an ancient sun—whose energy has been held hostage by dead plants for eons.

George: Okay so the energy in the laptop comes from the ancient sun—but where did that energy come from?

The sun’s energy is all a result of nuclear fusion going on in the center of the sun—the process of atoms being squished together under unthinkable pressure until they combine together into a single atom, releasing a lot of energy in the process. It’s the opposite of nuclear fission (which is how nuclear power plants make energy) and looks something like this:

Nuclear Fusion

So the energy explosion from the nuclear fusion shoots photons outwards from the sun’s core, and those photons unimpressively take roughly 100,000 years to reach the sun’s surface, but then only eight minutes to reach the Earth from there, which is when they can first be absorbed by a plant.

George: And where did that energy—the nuclear fusion—come from?

Nuclear fusion happens in a star’s core simply because the immense amount of matter of a star creates superb gravitational pressure in the core—so strong that it ignites nuclear fusion.

And what is gravity?

You’re quite the kid, George.

Gravity is curved spacetime—a “dimple” in spacetime made by matter—and in the case of matter as massive as the sun, a really deep dimple.

So there’s the real origin of the energy that’s powering my laptop—a deep warping of space-time caused by the mass of the sun, which results in nuclear fusion, which 100,000 years later results in a plant on Earth absorbing the energy as part of its photosynthesis. The energy is then trapped in the dead plant underground and squashed over time into a fossil fuel like coal, which 300 million years later is dug up by a coal miner, shipped off to a coal power plant, and burned—which releases the light and heat of the ancient sun as fire. That fire is used in the power plant to heat up water to a boil, which releases the energy as steam, which spins a turbine inside a generator, which sends the energy shooting out into the power grid as electricity, which then flows out of the outlet in my wall when I plug in my power cord and into my computer, and now my laptop is on.

Why is my laptop on?


george clapping

Thanks, George. I was pretty impressive just now, it’s true.

Anyway, this long process tracing my laptop’s power to the ancient sun’s gravity can be applied to non-electric energy too—your car running (the jumble under your car’s hood functions as a mini power plant, burning gasoline, which comes from oil, to release its ancient energy), a candle burning (how much cooler is a candle now that you realize that the wax comes from underground oil and has 300 million year old sun energy stored in it that’s finally released as a flame when you light it), or almost any other kind of energy in your life.

Even your own body. Why can I type this post with my fingers? Because my body has energy from the food I ate, which was either plants or animals who got their energy from plants, which brings us back to photosynthesis—in this case, recent photosynthesis, which means the sunlight powering my fingers is pretty new (but due to the photon lag time, the fusion that generated the sunlight, and the gravity that forced that fusion, are still 100,000 years old).

So that’s that, George—did you have fun?

George: I did. But wait—why does matter create a dimple in space-time?

Great! I’m glad you had fun, George. Run along, now.


1. Photosynthesis is unbelievable. The entire food chain is just creatures stealing energy from other creatures—sometimes it’s an animal eating a plant or another animal, sometimes it’s calmer, like a bee stealing a flower’s nectar. But we rarely stop to ask, “How did all that energy find its way into the food chain in the first place?” With photosynthesis, of course. Plants figured out how to turn the sun’s energy into “food,” and this is the origin of all the energy throughout the food chain. Photosynthesis is the key moment when natural energy enters the world of biology—I don’t think about this enough.

[Reader David B. points out that there’s another way energy gets into the food chain: “Deep below the surface of the ocean are thermal vents where entire ecosystems live off the process we call chemosynthesis. There, chemoautotrophs drive the food web using inorganic sources of energy such as hydrogen sulfide.”]

Check out Energy for Dummies for a quick Wait But Why crash course on all the relevant energy sources in today’s world.

Related Wait But Why Posts

Putting Time In Perspective
The AI Revolution: The Road to Superintelligence
What Could You Buy With $241 Trillion?

  • Bonolo

    I could not love anything more than I love this blog.

  • Erik

    But you stopped when it gets REALLY interesting!

    That dimple in space-time was created by the uneven distribution of matter in the universe after the big bang. If all of the matter in the universe (or, more accurately, the <1% of matter that wasn't instantly annihilated by antimatter) was evenly distributed after the big bang, NOTHING would have ever happened in the universe. But, just as a stroke of small percentages conserved a tiny fraction of matter from being wiped out by antimatter, a stroke of small percentages made a weak distribution PATTERN after the big bang, which gravity slowly coalesced into filaments of gas (still the largest structures in the universe) that eventually formed balls of gas that eventually collapsed and ignited into stars!

    So, your laptop works because of a microscopically improbably statistical quirk of the big bang!

    Even more interesting, on a side note, is that the universe is ruled by entropy. Things break and fall apart. Broken eggs don't magically fly back together. The universe goes from a more ordered state to a less ordered state, and a hotter state to a cooler state. All of these statements represent entropy, and entropy also essentially means that time flows forward, not backwards.

    But, then, how are we here? Well, the one fundamental for that works AGAINST entropy is gravity. Gravity is almost the opposite of entropy. It allows dispersed things to come together, creates order out of chaos, heat out of cold, etc.

    And because gravity does all those things, it allows for very narrow windows of goldilocks conditions where entropy decreases and complexity increases. This is where we live. A little pocket of anti-entropy. It's what allows processes like evolution.

    Think about this: gravity allowed the first stars to form out of the simple elements from the big bang. Until then there was no Iron or Gold or other elements on the periodic table other than the first few. These formed in the hearts of the first stars. The first "Goldilocks" zone was the fact that some of the filaments of gas were structured to allow for starts. The second was that some of those starts became big enough to truly ignite and form heavier elements at their core. The third is that some of THOSE stars were big enough to go nova and seed the universe with the heavy elements at their cores, which then could form rocky planets around a next generation of starts. Some rocky planets are just wet and hot enough and have just the right combination of elements to introduce complex chemistry for the first time, and eventually organic chemistry, and then biology. Each of the sciences spins off from the one before it as complexity rises as the goldilocks conditions allow for it.

    You can keep pulling at this string even more by following to multicellular creatures, sexual reproduction (complexity accelerates), tool-making (direct manipulation of complexity), speech and culture ("societal memory" beyond a single organism in how to create and maintain complexity), writing (the same can now pass from a long-dead mind to a live one), to the Internet (a full global archive of knowledge).

    So you are here, and your laptop is here, and it's power is here, all because of gravity creating pockets of the universe that are anti-entropic. We all live in a bubble. Thanks to gravity.

    • Wait But Why

      Favorite comment ever.

      • Tomás Magalhães


      • Erik

        Thanks! That means a lot!

        I think you’d love the Big History Project (the web education series, not the History Channel show that it spun off): https://www.bighistoryproject.com/bhplive

        Anyone can sign up as an “educator” and get access to the course material. It’s fascinating and inspired my thoughts above (with some of my own interpretation layered on top).

        Add it to your Dark Playground. Maybe one day you’ll write about it in order to pull it at least into the Dark Woods! It definitely aligns with the type of posts you write.

        • jozen

          Excellent seeding Erik. And no mention of monkeys or monsters.

          I also enjoyed your first comment, realigned my perspective; How will I pass on my energy today? Thanks!

    • Anonymous

      Well, but the real question is, “What’s the connection between mass and that dang ol’ dimple?” I mean, it’s one thing to say, “Hey, space-time is like a rubber sheet, and mass is this thing that deforms the sheet, creating a ‘gravity well,'” but that doesn’t really explain how mass can do this. Or really, in what way space-time is like a rubbery sheet.

      Back in college, a professor pointed out that it’s kind of weird that mass features in two fundamental physics equations:

      (Force) = (mass) x (acceleration)


      (Force of gravity between two things) = (mass 1) x (mass 2) x (a bunch of constants) / (square of distance between objects)

      That first one, F = ma, we all kinda recognize, because it’s harder to accelerate a bowling ball than a tennis ball. The second one, F = Gmm/r^2, is a lot harder to relate to in our ordinary lives, though we all live with the consequences.

      Anyway, the professor’s point was, “Geez, why should it be that mass shows up in those two equations? They really don’t have much to do with each other at first glance. Why should an object’s inertia tell you how strongly other objects will be pulled toward it?”

      I’m guessing at this next part, because at this point I changed majors, but I bet I’m right: an object’s inertia, i.e., how much ooomph you’ve gotta put in to move it, is because (in a manner of speaking) you’re not just moving the object, you’re trying to make a ripple in that rubbery sheet with the dimple: you’re trying to shove the dimple (and the massive thing at the center of the dimple) elsewhere on the sheet.

      So there’s some weird thing where matter connects to that rubbery sheet of spacetime somehow, and the more massive it is, the more ability it has to muck up that sheet of space-time. From what little I understand, this has something to do with a quantum thingy called the “Higgs boson” and the “Higgs field,” but I’d be lying if I said I understood the first thing about it.

      P.S. Here is a weird thing about inertia and gravity! Let’s say you’ve got a guy who weighs 200 lbs on earth. It takes modest effort to shove that guy around. But if you put him on a space ship, and he zooms around at a really high fraction of the speed of light, it becomes HARDER and HARDER to accelerate him. It’s as if he’s getting heavier and heavier, the faster he goes. Except he’s not creating a bigger dimple in space-time, that is, he’s not actually getting more massive in the gravitational sense. Instead, what’s happening is that F = ma, this relationship between how much force you gotta put in to accelerate a particular mass, is beginning to break down when you go super-duper fast. The conversion between force and speed is becoming less efficient. This is a consequence of Special Relativity. And I used to understand it 20 years ago.

    • Wait but why!

      Erik, explain to me how the big bang explains how the very first matter was created in the first place? I’m talking about the very very very very very first thing that was created. Do we just not know? Do we make up religion to say that a god created it through intelligent design? I want to know before the big thing, what was the first thing created and how did it form? IS there simply no explanation?

      • Erik

        All we know is that at extreme temperatures matter and energy as basically the same thing, and at the moment of the big bang that all of it was compressed together in a single point in space-time smaller than an atom. Everything. In the universe.

        The thinking is that the big bang did not “create” this matter and energy. It just represents the point at which space-time itself, and the matter and energy within it, began to move outwards and cool down. So, in theory, all that stuff was already there at the moment of the big bang, not created by it.

        So what happened before the big bang? Was there just an infinitely dense and heave pinprick of existence sitting there for eons? (Not that the question is entirely relevant because TIME did not exist yet.) Was there a prior universe that collapsed in upon itself in a “big crunch” that then rebounded? Is reality actually a projection of multi-dimensional membranes of which we can only sense and experience a small aspect, and a big bang occurs every time two such membranes make contact?

        No one knows. And no one can know. Ever. Maybe one day we will have models sophisticated enough to run on computers powerful enough to hint via simulation that we might know, but the truth is that anything before the big bang is inherently unobservable, and therefore hidden from science.

        Does that mean that it’s god’s theater curtain? Or is it just physics? I have no idea. But it is certainly THE most poetic thing in the universe, ever. Maybe that poem was written by god. Maybe it was written by math. Maybe math is god. Take your pick.

        • katsumii

          Hi… Your comments are beautiful. 🙂 As a coincidental passerby, I thank you for sharing your insight. What a wonderful website of great minds, thinkers and observers. I’m so happy to have checked the comments and come across yours.


    • Wait but why!

      Erik, explain to me how the big bang explains how the very first matter was created in the first place? I’m talking about the very very very very very first thing that was created. Do we just not know? Do we make up religion to say that a god created it through intelligent design? I want to know before the big thing, what was the first thing created and how did it form? IS there simply no explanation?

      • LOL

        There’s a Discovery Channel for that. And no, we don’t know. What do you think we tiny specks of humans are – God? lol

  • Erin

    Ugh, MARRY ME. I <3 your blog.

  • Margaret


  • gionni78

    That was absolutely great!

    One remark: I suspect that the “electron stream shooting into the city grid as electricity” concept might be misleading (that would be far too slow). It’s more like electromagnetic field variations propagating through the grid.
    But then again, many years have passed since the times when I was a physics student…

    • Stephen Braun

      I was going to make the same point. It’s not that electrons “shoot” anywhere. It’s that the electrons in the wire get rapidly pulled back and forth, back and forth, back and forth, by the alterations in the poles of the magnets in the generator coils. Picture a rope with a bunch of knots in it. The rope doesn’t move much at all, just back and forth, but if you grab the rope at any point, your arm will be yanked back and forth by the nearest “knot.” If, instead, you connect some device to the “rope” you can generate work by that back-and-forth motion. Cleverly, we’ve found all sorts of ways to translate that basic alternating current into heat/light/motion/laptop screen pixels/etc.

      • Wait But Why

        Good correction. And awesome explanation with the knots in the rope.

        I changed “electrons” to “electrical currents,” which better conceals my lack of understanding of how a generator works.

  • Kevin

    Great post!

  • Scott

    Okay, loved it but….. Why is your laptop on??? The world, may never know.

  • Vince Marshall

    Outstanding job! This blog is funny as hell and informative to boot. I’m a Mechanical Engineer, Certified Energy Manager and have struggled for years to explain to laypeople what you just did. No one EVER talks about the Carboniferous Period. Well done!

    Would you mind if we put a link on our website to yours? We’re Cherokee Energy. http://www.cherokee-energy.com


    • Jordan Urban

      If you send this request in an email to contact@waitbutwhy.com, we’ll respond to you with more details on our republishing criteria!

  • Nicole K.

    Erin stole my comment. But there are two of you, right? So can the other of you marry me?

  • JRF

    FANTASTIC!!!!!!! Thanks a lot. Now I can’t think enough about photosynthesis either.

  • Michael P.

    Just: thank you. This is the best blog in any universe.

    Warm regards (c/o the sun’s energy in macaroni and cheese),

    PS: I’m relatively certain that I accidentally posted a comment here from Facebook, thinking that I was Sharing this episode to Facebook, resulting in the feeling that I am your 81-year-old grandmother and I don’t understand the Internets. If you find it, please destroy it.

  • JH

    Wait, but… Why?

    My understanding is that it’s actually more or less impossible to say “This particular power station is powering my laptop.” In sort of – though not exactly – the same way that it’s impossible to say “This particular tributary of the Amazon brought the water that’s carrying my boat out to sea.” Or I suppose “This particular Amazon employee caused me to have this new book.”

  • Y

    Marry me

  • wobster109

    Was lovely. More presidents?

  • Rae

    Greatness!! I actually understood and it made sense!! And Eric – before the ‘big thing?

  • C

    Strangest side phenomenon of this blog and its posts on coal and microbes is the comments from women falling for waitbutwhy. I hope all the nerd guys out there are paying attention to this.

  • Nicole

    I somehow feel very Zen about everything after reading this… lol

  • Bryan

    Thanks for sharing you journey with us. You are quite inspiring.

  • Mel

    I actually dont know how I lived not knowing this. Thank-you!!

  • Cindy

    I love this blog and how your brain works. Enlightening!

  • Anonymous

    Amazing as always. WBW is transforming the world!

  • Candice

    Amazing read! I loved it – thank you 🙂

  • Will

    Great post, but I would like to point out that at the cellular level, photosynthesis is far from simple! There are so many steps and the cells in plants actually create and destroy so many intermediate carbon chains using so many different organelles within cells, it’s dizzying.

    • James

      No one said it was simple, plants are amazing and vital to the world’s survival, yet no one cares about destroying forests and the environment at all, so ignorant and sad

  • EmJay

    Fantastic post and comments. Wait But Why (both of them) should marry Erik. Think of the babies they could make.

  • anonymous

    “Photosynthesis is the key moment when natural energy enters the world of biology” That is very cool. As are all these connections which you used to make that point. By the time I’d read through the many questions and answers about energy changing, that statement seemed magical. Wonderous.

    I think I knew a lot of these separate facts. Maybe I learned some of this along the way. But I never connected the dots. Putting it this way, in a condensed package helps it to make more sense. Thank you.

    (It makes me question the value of a 10 week long class. It may be too much time to cram with information that just gets lost. The magic of it gets diluted somehow. And putting knowledge to the test by answering one simple question-very fun.)

    A quote comes to mind-from my refrigerator magnet (a line from the movie Paul): “We are people of science. We believe in the establishment of biological order through the maelstrom of physical and chemical chaos.”

  • DS

    I was a STEM major in college, so I didn’t enjoy READING this one as much as the others. But the fact that you WROTE it in a way that makes it simple for everyone to understand, regardless of academic background made me enjoy it a ton. It’s such an interesting concept that everything on Earth, (and, arguably, the Earth itself) is simply a vessel for solar energy that’s been converted into different forms. A big exploding ball of gas made all this shit and sustains it. Great article and I hope a lot of people learned something they’d otherwise have to suffer in class for.

  • Derek

    This is the best damn website on the interweb!

  • Voracious Reader

    I learned more from this post than I ever did in classes.

  • daChipster

    First: awesome site, best ever, but don’t marry any of these people until they’ve qualified under the life partner posts which, by the way, why does it have to be ONE life partner? You lose readers that way.

    Second: more dead presidents, please.

    George IS rather impressive for a six-year-old, but you slipped the next two curveballs by him.

    Third: Wait! But why is your laptop on WITHOUT BEING PLUGGED IN? Sure I could look up batteries and electro-chemical yadda yadda but you tell it better.

    Fourth: Copper wire and magnets seem to also be the province of underpants gnomes. Spinning copper wire and magnets -> ??? -> ELECTRICITY.

    Sure I could look up electromagnetic fields, but you tell it so much better!

  • Anonymous

    I love this site so much — KING ME!!!

  • Anonymous

    What’s cool about Wait But Why is that it digests and delivers in a totally user-friendly (and hilarious) package a ton of information about basic elements of my life that I’ve somehow accepted not knowing much about. Keep it up — this site will make history.

  • Maria

    another great post! loved it!!

  • Danny Keith James

    Energy is not a thing. It’s a measurement of work potential.

  • Marianne G

    Why is your laptop on? Did you – or didn’t you answer the question? 🙂
    Might it be ‘on’ ( all the time) because it creates a sense of not being in the realm of the ‘instant grat monkey’ allthough we are much of the time? I mean – looking from the outside no one can tell whether we are just working hard, what do we tell ourselves? Hard to know 🙂

  • Kaitlin

    Awesome read! I learned so much while being entertained. As I teacher I think you’re really onto something! How electricity works is one of those things that I always thought about and never really understood. Thanks for clearing that up. Now onto another challenge if your up for it: cameras. How is it possible to click a button and capture an exact moments in life??

  • William

    Amazing it’s all I have to say:)

  • Roger

    Do you take requests?
    I’d like to know why the passport is the one form of ID that the world agrees on. Like, who is the multinational governing body that tells all the countries that they have to accept passports? How can all the countries in the world agree on this one thing and nothing else?

  • BW

    I am pursuing a Masters degree in Power Engineering, so I was happy to see a post on this topic! (and the related energy post) If you are interested in further reading, I suggest you pursue the concept of exergy and exergy efficiency. You touched on this a little with the comments about electricity. Electricity is basically the “best form” of energy, and it is considered to be pure exergy.

    This also explains why electrically powered heating and cooking appliances are such a waste. We are basically burning fuel in a power plant to generate heat, converting the heat to electricity with huge losses, and then using that electricity to generate heat. What a terrible system! Combined-heat-and-power cycles, (power plants that bleed off some steam for residential and industrial heating) along with more use of heat pumps could save a lot of carbon emissions.

    On the subject of heat pumps, (basically a power cycle run in reverse) these normally have a coefficient of performance around 3-4. This means that one watt of electricity (used to power the compressor in the heat pump) will give you four watts of heating! Impossible? Nope, the extra energy is coming from the air outside your home. Way better than using one watt of precious electricity for something as wasteful as a space heater.

    Back to exergy … Exergy gives us more insight to the generation of electrical power, especially in the calculation of efficiency. People quote efficiency numbers willy nilly, but there are actually many ways to measure efficiency. When comparing different technologies like fossil fuels and renewables, we need to take this into account. For example, most of the energy inefficiency in a conventional coal plant comes from the conversion of heat to work. But solar panels and wind turbines skip the heat engine step entirely.

    These technologies directly convert the “primary energy” into electricity without the intermediate steps of coal to heat, then heat to work. In the boiler of a coal plant, there are large exergy losses due to the high temperature difference between the fuel and the working fluid (usually water). So energy efficiency alone does not tell us the whole story, and makes the renewables look worse than they really are.

    Anyway, sorry for such a long comment but I thought I would just add some more insight to the topics you covered. And thanks for the post! I thought it was great.

  • Anonymous

    I’m overwhelmed.

    The sun being stored in mud in the ocean, that’s crazy.

    It’s funny how so many ideas from ancient greek mythology and philosophy (they had those weird speculating physics philosophers) are in some way true.

    • Matt Menezes

      If you make a ton of guesses, you’ll be right occasionally. That being said, the ancient Greeks were pretty bad at science. IIRC, they thought all things are made of 4 basic building blocks: earth, fire, water, and air. Little did they realize that a single element, Oxygen, is present in earth, fire, water, and air.

      However, going down further, every element is made up of protons, neutrons, and electrons. Going even further to fundamental particles, it’s two types of quarks (up and down) that make up all baryonic matter and electrons and neutrinos that make up the leptons. Those 4 fundamental particles, while only representing about 4% of the mass/energy in the universe, make up all the stars/planets in all the galaxies in the universe.

      Upon further inspection, I guess the Greeks thinking 4 fundamental things make up everything we know is right afterall!! 😛

  • Dan

    So what is this photon lag time? I understand that there is a time between energy absorption and photon emission but that is tiny. There is a delay between the sun and the earth, but that is something like 8 min. Maybe a delay with the photons getting out of the solar gravity well? I cannot think that would be years, would it? Any link that I could read up on this?

    • Wait But Why

      Check this out—http://sunearthday.nasa.gov/2007/locations/ttt_sunlight.php

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  • CK Louis

    Did you rip off my joke for the 4 year olds asking “why” all the time?

    • Jennifer Gagnon

      This post reminded me of that bit right away.

  • DeeDee Massey

    This was more of an explanation about HOW the laptop is on, rather than WHY we extract vast amounts of the Earth’s resources to operate such a wondrous technological device….

    to watch cat videos.

  • MaJo

    I feel smart. Holly shit.

    • Matt Menezes

      Who is Holly? ;-P

      • MicroMatrixx

        Shit is obviously

  • James

    I’ve always been a little bit of a pyromaniac, but this line explains it beautifully. Energy really is an amazing thing. “Fire is the light and heat of the sun, absorbed into the wood for years, finally being released.” Now I’m even more excited that my new apartment has a real wood fireplace!

  • Jaro

    You state that the sun gets its energy from the suns gravitational pull which is only half the story…
    The suns gravity does cause the fusion, but in the process of fusion is where the majority of the energy comes from. By two atoms coming together to become one, they are reducing their atomic mass which intern converts itself directly into enegy which can be represented by Einstiens equation E=mc^2. The amount of energy released is equal to the loss in mass from the two atoms combining multiplied by the speed of light squared, noting that the speed of light is 3,000,000 m/s, squaring it and multiplying it by the tiny amount of mass released by the atoms combining results in a tremendous ammount of energy released per atom created which is happing at a significant rate.

  • korakys

    Bah, I’m in Wellington right now so about 99% of the electricity powering my computer is renewable*. I think your “almost certainly” phrasing is too strong. Nice post otherwise though.

    *Mostly hydro, with wind playing a supporting role.

  • Tipsy

    And where does the hydrogen sulfide come from??

    BTW thanks, great post. The reason I didn’t think much of photosynthesis in school is because none of the teachers ever put it in its full context, and explained why it’s such an important idea in the first place.

    How energy comes into our organic systems.

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