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  • Twenty-one grams.

  • That is the mass of all of the electrons in your body if, like me, you weigh about 70

  • kilograms.

  • Now all of the mass comes from the Higgs mechanism, which means that as your electrons are traveling

  • through space time, they interact with the Higgs field and it is that that gives them

  • their mass.

  • It slows them down and stops them from traveling at the speed of light.

  • But most of your mass doesn’t come from the Higgs mechanism.

  • And neither does all of this stuff that you see around you.

  • The mass is coming from somewhere quite different and that is because most of your mass and

  • most of this mass comes from neutrons and protons and they are not fundamental particles.

  • They are made of constituent particles called quarks.

  • Now the theory that describes quarks and their interactions with each other through gluons

  • is called quantum chromo dynamics.

  • And chromo is the Greek word for color.

  • So in some way these objects are meant to carry the color charge.

  • But they are much, much smaller than the wavelength of visible light, so there is no way that

  • they are actually colored, but it is a useful analogy that helps us think about how they

  • interact and the particles that they can make up.

  • Now the rules are pretty simple.

  • In order for a particle to exist, it must be colorless or white, like this house.

  • Now you can accomplish that in two different ways.

  • You could make three quarks in where each one is a different color, red, green and blue,

  • so overall they combine to produce white.

  • Or you could use a quark and an anti quark where one is a color like green and the other

  • is its anti color, say, magenta.

  • Now what I would like to do on this little patch of beach behind me is simulate how quarks

  • actually bind together and form different particles.

  • Now for this you need to remember that in the last video we talked about how empty space

  • is not truly empty.

  • So the beach here is has these undulations in it which represent the fluctuations in

  • the gluon field.

  • But you have to imagine this beach sort of rippling and these bumps coming and going.

  • Now that is really important, because to get rid of those fluctuations actually takes energy.

  • And this is an important part of binding the quarks together.

  • The existence of quarks actually suppresses the gluon fluctuations and creates what is

  • called a flux tube, an area where there is really nothing in the vacuum and that is in

  • between this quark and the anti quark.

  • And that pairs them up and creates what is called a meson, the quark, anti quark pair.

  • What is interesting about that flux tube is that as these quarks become more separated,

  • the flux tube remains the same diameter and the same sort of depth of suppression of the

  • field, which means that the force doesn't actually increase.

  • It is not like a spring.

  • It is not like an elastic band.

  • The force is the same that is pulling these quarks back together.

  • But you are putting more work in as you move these quarks and anti quarks further apart.

  • And so for a time people thought: Well, these quarks are always going t be confined, however

  • far you move them.

  • You are just going to get a really long flux tube.

  • But what actually happens is you that you put in enough energy that you can actually

  • create a quark, anti quark pair.

  • >> Nevertheless, the quarks are still combined.

  • You can never see an individual quark, because if you try to pull it out, you put so much

  • energy into the situation that another quark, anti quark pair will be created.

  • >> Now to form a proton, we are going to need an up quark, another up quark and a down quark.

  • Now the standard model of a proton that you have probably seen involves these quarks bounded

  • together by little gluon springs that go between them.

  • >> We know that that picture is totally wrong now.

  • Even in the best sense you might have hoped that you would see flux tubes around the edge

  • of the triangle.

  • But we know that, in fact, they don’t do that.

  • That you get these y shaped flex tubes.

  • >> The crazy thing about a proton is that there may be more than three quarks there.

  • You see, you can have additional quark, anti quark pairs pop in and out of existence.

  • So at any given time there could be five or seven or nine, any odd number of quarks could

  • make up a proton.

  • So this is what a proton actually looks like.

  • You can see that the quarks like to sit on those lumps in the gluon field.

  • And you can see the two up quarks and a down quark, but there is also a strange quark and

  • an anti strange quark, which is strange, because you don’t normally think of these quarks

  • being inside a proton, but they can be at any particular point in time.

  • And you can also see that these quarks have cleared out the vacuum.

  • And you can see that there is kind of these flux tubes which are the areas where the gluon

  • field has been suppressed.

  • And that is really what is binding these quarks together.

  • >> That is the strong force that binds quarks into the heart of the proton.

  • >> It is intrinsically related to the fact that clearing out those fluctuations has more

  • energy than where they are.

  • >> That is right.

  • It costs energy to clear the vacuum.

  • >> So where is the mass of the proton really coming from?

  • Well, of course, the constituent quarks do interact with the Higgs field and that gives

  • them a small amount of mass.

  • But if you add up the mass of all the quarks in the proton it would only account for about

  • one percent of its total mass.

  • So where is the rest of the mass coming from?

  • The answer is: energy.

  • You know, Einstein’s famous equation: E equals mc squared.

  • Well, that says we have got a lot of energy for just a little bit of a mass.

  • But if you rearrange the equation you can see that we can get an amount of mass if there

  • is lots of energy there.

  • And that is really where most of the mass of the proton is coming from.

  • It is from the fact that there are these energy fluctuations in the gluon field and the quarks

  • are interacting with those gluons.

  • That is where your mass is coming from.

  • It is coming from the energy that is in there.

  • You know, Einstein talked about, well, if I had a hot cup of tea, it would actually

  • have a slightly greater mass than the same cup of tea when cold.

  • And he was right.

  • I mean, you can’t measure it with a cup of tea, but most of your mass you owe to E

  • equals mc squared, you owe to the fact that your mass is packed with energy, because of

  • the interactions between the quarks and these gluon fluctuations in that gluon field.

  • I think it is extraordinary, because what we think of as ordinarily empty space, you

  • know, that turns out to be the thing that gives us all most of our mass.

  • I really want to thank Audible.com for supporting this episode of Veritasium.

  • In case you don’t know, Audble.com is a leading provider of audio books with over

  • 100,000 titles in all areas of literature including fiction, non fiction and periodicals.

  • You know, one of my favorite books is by James Gleick.

  • It is called The Information: A History, A Theory, A Flood.

  • And if you head on over to Audible.com/Veritasium you can download it right now for free.

  • Or you could pick another book of your choosing.

  • You know, it is great to have support from people like Audible, because that allows me

  • to keep this content for you for free.

  • So please go check it out.

Twenty-one grams.

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あなたの質量はヒッグス粒子からではない (Your Mass is NOT From the Higgs Boson)

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    林宜悉 に公開 2021 年 01 月 14 日
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