World’s Most Asked Questions: What Is Energy?

As you probably know by now, we’ve been
working with Google and YouTube to answer ten of the most popular science questions
asked on the internet. And I gotta hand it to you, because there
are few questions that are as confounding and complex and fascinating and inspiring,
as this one the collective consciousness has spewed forth: What is energy? I’m Hank Green, and this is the World’s
Most Asked Questions. [Intro] Energy is everything. It’s everywhere. It’s
one of the true constants of the universe, because as long as there’s been a universe,
there’s been energy. And while it comes in lots of different forms
that can seem different to us, they all amount to the same thing: Energy is the ability to
do work. And work is just the act of displacing something
by applying force. So, say you stomp on a stomp rocket. The force
of your foot hitting the pedal is turned into the force of air leaving the cannon — sending
your rocket sailing. Or maybe you’re enjoying a nice patty melt
— the energy from that food is broken down for all of the quadrillions of cells that
you have to do all of the things that they have to do — make copies of your DNA, assemble
and repair proteins, transport materials from one place to another, make muscle cells contract
— you know, all the stuff of being alive. That rocket sailing, your cells toiling away,
your phone or computer being on right now to watch me — that’s all work being done. And the ability to do these things is inherent
in everything around you. Even things that look inert, completely lacking in energy.
Like this log. This log, for example, is chock full of chemical
energy because it’s made up of combinations of carbon and hydrogen and oxygen formed into
lignin, which is the stuff that makes up wood. All of the bonds between all of those atoms,
in every molecule of lignin, contain energy. How do I know? Because if I were to apply
enough extra energy, like as heat, to break those bonds — it would release that chemical
energy as fire. That chemical energy also the kind of energy
you get from that patty melt — your body is fueled by the chemical bond energy in sugars,
fats, and proteins. But this log also contains nuclear energy! Each atom in this wood has a nucleus, made
of protons and neutrons, and the energy that binds them together is one of the most powerful
sources of energy in the universe. If you could split one of the atoms of carbon
or hydrogen in this log, and rip those protons and neutrons apart, it’d release some of
that energy. There’s so much nuclear energy in each atom that, if I could unleash all
of it that’s in this log? There’d be a giant smoldering crater where I’m standing and
everyone in the town of Missoula, Montana would be dead. So, everything that’s made of atoms has
nuclear energy locked up in it, but also, it turns out, that mass and energy are the
same thing! You might have heard of this little equation
that a German patent clerk came up with about a hundred years ago: E=mc2. And there are SO MANY OTHER KINDS of energy
that I’d love to get into if we had the time … .. but even though they may seem different,
they can all be used to do work, whether it’s driving a turbine, or moving a engine piston,
or allowing the screen on your tablet to glow. Or, if it’s that most mysterious of energies,
dark energy, causing the universe to expand more than it seems like it should. But here’s the thing to remember. Once the work is done, the energy isn’t
done. Because energy never goes away. It can never be destroyed, and in the same
way, it can never be created. It can only be transferred from one source
to another — like, how the energy in the plants and animals that were in the patty
melt were transferred into you — or it can be transferred from one form into another
— like the chemical energy in the wood being transferred to light and heat as fire. You could think of the universe as a constant
flow of energy, and we are just little pit stops along the way. Everything your body is doing right now — whether
it’s your lungs absorbing oxygen, your heart pumping blood, your brain cells firing as
you watch me and learn things — all those things are using recycled energy that’s
been around since the origin of the universe. And by simply being alive, you’re releasing
that energy back into the environment around you, to be used by other things in other ways. So Internet, to answer your question: Energy
is everything. And for those of you who answered our questions
on our SciShow survey, where you feel like you get your energy may be keeping you up
at night. Survey takers who have a hard time falling asleep nearly every night get their
energy from knowledge first, second from purpose. Least likely? From exercise. Of all the fascinating questions in the world,
what question do you want to see answered most? Let us know on Facebook or Twitter or
down in the comments down below and we will aim to answer those questions in a new video
at the end of the month.


  1. What i wonder is why does this Universe even exist?
    I know Energy can neither be created nor destroyed,
    so it means everything that is in this Universe has always been there, and will always be there,
    including you, because the atoms that made you were always here, and will always be here.
    Even after you are dead in your physical form.
    So, why do all these trillions and trillions and trillions of atoms exist?
    Wouldn't it have been easier to just be nonexistent?
    Because to exist, requires energy, and work on that energy.

  2. What is energy? The ability to do work.

    What is work? Force times distance.

    What is force? Mass times acceleration.

    What is mass? o.O energy?

  3. If this video is found unhelpful to you and you 're looking for the definition of energy…

    According to most textbooks on Basic Science and Science, Energy is the ability to do work, the strength and vitality needed to sustain good physical and mental activity and the capacity of a system to do work.

  4. 3:12 Wrong, it can be created since the universe keeps expanding.

    I feel smart although I still haven't truly understood E =mc2 but I will very soon… very soon comrades… very soon…

  5. How has energy existed since the beginning of the universe if energy was needed to create the universe? Canโ€™t you say energy has always existed?

  6. E=Mc2 means that matter and energy are interchangeable. Thus there are 4 states of energy as it solidifies into denser forms of existence; energy, gasses, liquids, and solids. Examples are= fire, air, water, and earth. Take water for example; it can be solid-ice, liquid-water, gas in clouds, or desolidified further into its basic building blocks of hydrogen and oxygen.

    Thus energy can be described as the basic building blocks that make matter what it is. Energy is the software that makes the hardware work and exist as it does.

    The basic rules that govern one of the 4 states of energy governs them all, such as; displacement, friction, motion, resistance… etcetera. To understand one will allow you to understand them all.

    The difference between information and knowledge is your personal ability to apply information into your life. When you are able to manipulate and create something it is then knowledge and no longer simply data or memory.

    This is the way you can tell the truth of all things when you can create it yourself or at least use it to your benifit so as to live a happy life.

    Thus we know we truly don't understand gravity because we cannot yet manipulate or create it.

    -Gravity is created when matter displaces energy.

    The universe is 96% energy and 4% matter. Matter is the minority. Solids displace less solid forms of energy. So it seems obvious that this would apply to everything not just liquids or gasses but the less dense energies also.

    So many things can be done and have been done to prove that matter displaces energy and that this displacement is what we know as gravity. Feel free to take this information and turn it into your own personal knowledge. But as always let living a happy live be your overall goal and you will not go wrong.

  7. Bfjbvugfisbhvhguifsblj;vfiabvp;nfuiabvjfibnfejiblngfjsiolyeetfjjknvlfjka;vbnrio[nrionrav;jriao[vgrmiv[re

  8. no such thing populx or most or cofounx or facinx or inspirix or not, say, ca, say any no matter what and any be perfect

  9. You answered nothing!!!

    What is energy????

    Don't tell me the things i can do with energy.
    Just tell me what it is!!

    Magic? It seems so. No one knows what really is, only its purpose!!

  10. WTF…this is why scientists need Philosophy…the question is "WHAT **IS** 'ENERGEY'" — NOT "what are some examples of energy," "what is energy used for," "how to get energy"…sheesh…!!

  11. i never understood energy as myself, but when i started to become aware of my environment and i started to become more and more conscious of the present moment as i lost the sense the self the ego and my emotional attachment to the past, with meditation practices and becoming aware of the thoughts i was producing. i started to feel in control of my energy, and that gave me the realization that i am energy and we are all energy, and we have the power to do anything with it, we can transmuted in to creative activities. we are always in control of our energy, we just have to transmute it.

  12. So no one knows what energy is,.They know what it can do but not what it is. Not such clever boys after all then.

  13. I donโ€™t understand the concept of energy canโ€™t be created.
    Some people can clearly create more energy than others and that has nothing to do with food only mental power.
    When you are motivated you can create a lot more energy, is it not true?

  14. The definition sounds circular. Energy is the ability to work but work is the transfer of energy. But energy is neither created or destroyed but my mass is energy? What the hell – What is energy? Lol ๐Ÿ˜‚

  15. No. NO!

    If energy were the ability to do work, then when things are in thermal equilibrium (like the universe at the death of heat), then work would still be possible. However, it is impossible (as our experience leads us to think) for work to be done when everything is in thermal equilibrium. So our universe in thermal equilibrium would still have all the energy it ever has had, but no work would be possible.

  16. shame that you did not answer what the energy is actually…. but here is the answer, energy doesn't physically exists, just the same way as for ex, the distance between two objects, that is just a communication tool to describe what is happening, as a matter of fact none of the physical units physically exists, they are statistical/communication tools to analyze/communicate what is happening with the material.

    The easiest the understand the distance for ex, does the distance exist? NO, im just tryin to tell you that how far i'm i from you so can predict when will i arrive to you, but the distance physically doesn't exist, it is a description , and the same way time does not exist , just as force, and if you think about all the other stuff you learnt in physics, like work, acceleration, speed, energy, those are all non physically existing things just an analyzation tools to describe what is happening. If you understand and know how to use those tools you might be able to design a product, by figuring out what has to happen to achieve your goal, and eventually you build up a device where things will HAPPEN the way you calculated,

    the whole physics should be actually renamed to something which actually shows what this field does, like "material/particle happenings analysation" and that would solve loads of confusion

  17. I think the title needs work cause the most asked questions is what is the meaning of life everyone who been to school knows what energy is!

  18. We are two physicists who did a podcast on the development of the concept of energy. Check it out here:

  19. Im still for him to explain what energy is… He never did explain it… It explained how energy behaves, but not what it is…

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