Why Don't Protons Fly Apart in the Nucleus of Atoms? RESIDUAL Strong Force Explained
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Published 2022-07-29
Prior Video explaining the evolution of QCD:
• Why Don't Protons Fly Apart in the Nu... …
SUMMARY:
Since electromagnetism is so strong, multiple protons in the nucleus of any atom like Helium should repel each other very strongly. So how do they stay glued together?...Because of a force that is even stronger than electromagnetism – 100x stronger, the Strong Nuclear Force.
This force is actually a RESIDUAL form of the strong force, and works via a different mechanism than the force keeping quarks inside nucleons. I review the science of quantum chromodynamics. This force not only keeps protons glued together, it is also responsible for 99% of the mass of objects. Only about 1% of the mass of objects come from the Higgs Field.
Protons and neutrons are made of quarks and gluons. A proton is made of two Up quarks and one down quark. A neutron is made of two down quarks and one up quark. Gluons within these nucleons are virtual particles so the number fluctuates, but there are 8 different types of Gluons which bind quarks together.
Both the quarks and gluons carry a color charge. It is analogous to an electric charge but works via a completely different mechanism, and it has nothing to do with optical colors. It is just a metaphor for a kind of charge property that quarks and gluons carry.
There are three kinds of color charges, red, green and blue, which combine to make a neutral charge. So just like electrical charges are conserved – positive with negative to make neutral, color charge is also conserved by either a combination of the three colors to make neutrol, or by color-anticolor pairs. There are anti-colors too.
Gluons bind quarks together by constantly exchanging color charge between them. This exchange occurs continuously. The constant exchange of gluons creates a kind of continuous bridge between quarks called a flux tube.
Electromagnetism, like gravity gets weaker as objects get farther apart. But the force between two quarks actually gets stronger as they get further apart. It works like a rubber band or spring. If you try to pull two quarks apart, the force between them gets stronger the further apart they are. This tends to pull a quarks back into the proton or neutron. However, if the quarks get too far apart, then the rubber band breaks.
When this break occurs, the energy required to break the rubber band creates a new quark and anti-quark pair, called a meson. This is called confinement in quantum chromodynamics because you cannot have free quarks. They are always confined together with at least one other quark. The newly created meson from the breaking of the rubber band is the key to how protons are kept glued together with other protons and neutrons in the nucleus.
What causes the quark-gluon flux tube to break and create a Meson? Although the color charges of quarks within nucleons combine to form a neutral color, such that the net color charge cancels out, quantum fluctuations ensure that this cancelation does not happen perfectly. This is especially true when nucleons are very close together.
Some color charge remains. This imperfect balance of color charge causes a residual strong force between nucleons.
This is called the strong nuclear force. It is mediated not by gluons, but by the exchange of mesons between two nucleons. It is the exchange of mesons between protons and neutrons that results in a residual strong force, also called the strong nuclear force, that keeps these nucleons tightly glued together.
This is a critical interaction because without it, there would be no atoms heavier than hydrogen because 2 protons could not bind together in the nucleus. And life as we know it would not exist.
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It is called the strong nuclear force. But note that this is distinct from the strong force which works within the nucleons keeping the quarks tightly bound together. The latter is mediated by gluons. But the strong nuclear force is mediated by mesons. Although the strong nuclear force is much weaker than the strong force keeping quarks tied together in nucleons, it is still much stronger than the electromagnetic repulsive force between two protons. So protons are still glued together even though they feel a strong repulsive electromagnetic repulsion.
CHAPTERS:
0:00 The enormous force of electromagnetism
2:18 The particles involved in the strong force
3:59 The mechanism of the Color Charge
6:24 Confinement & how virtual mesons are formed
7:45 What causes flux tube to break?
8:47 Details of quark interactions between nucleons
12:20 Difference between Strong Force & Strong Nuclear Force
14:18 How to learn the fundamentals
All Comments (21)
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I learned quantum field theory from Weinberg's books. He gives you all the maths and explains nothing about what it means. I wish I'd had your videos back then, you're amazing!
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I thought I understood this stuff. I missed the subtlty of the strong NUCLEAR force part of it and the mesons mediating it. Thanks Arvin. This was a great episode.
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I never realized the strong nuclear force and strong force were actually two different things, but this was a clear explanation. thanks!
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As a layman it took me this video to understand "strong force" and "strong nuclear force" are different ~~~ Thanks Arvin !
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Just for perspective, a proton weighs approximately 3.68x10^-27 pounds. 20lbs of force pushing against this mass is about 5.42×10^27 times the mass of the proton. That's 5.42 octillion times the mass of the proton pushing against it. The mass of the Earth is approximately 1.3 x 10^25 pounds. Imagine a person weighs 130 pounds (1.3 x 10^2) The forces pushing the proton are roughly equivalent to having 10,000 times the weight of the Earth pushing against a person. It's mind-boggling how much energy is contained in the nucleus. It's no surprise that nuclear reactions release so much energy. (In this example, I'm using pounds but in KG or grams the ratios would still be the same.)
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This was by far the clearest explanation I've seen of the strong force and how it works to bind nucleons together. Thank you!
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That was amazing! You are true to your channel's tagline to take something and explain it in a way the general puplic will have a chance to understand. This is the first time I believe I understand Feynman diagrams, thanks to your detailed animation. Suddenly I see myself in posession of an understanding of the strong nuclear force and its implication. On top of this, it explains to me the the existence and purpose of gluons and mesons. You make it look easy - in the same way acrobats in the flying trapeze make it look easy: It is thrilling to watch and looks great, but I know I would never be able to do what you just did. You don't just recite sciense news - you translate it and is able to teach the rest of us. Thank you Arvin!
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Are you considering a video to explain the weirdness of Technetium, and why it is never stable despite being such a light element? I’ve never heard a satisfying answer!
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very good explanation. I didn't quite "get" all of it but I did learn a lot. I think I now understand why protons stay inside the nucleus together, thanks for the video!
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Absolutely amazing! For me, as a chemist, the smallest things in the universe are protons, neutrons and electrons.
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Wow! I had no idea HOW the quark type, gluon and force jigsaw fitted together….You have explained the mechanisms involved with lucid clarity…Thank you so much Arvin.👍
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Excellent presentation. I understood a lot, I remembered a lot.
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I love this channel more than any other science channel on YT. You explain these extremely complex ideas in very understandable ways. I always learn things. Feynman would be proud!
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This is a great explanation, thank you Arvin. :) The question this leaves me with is why a nucleus only tends to be stable with a mixture of protons and neutrons. It's like there's a "sweet spot" in the ratio of how many protons and neutrons can make a stable nucleus for any given proton count, with a handful of less and less stable isotopes surrounding that preferred ratio, and then if the ratio is too far off the nucleus just isn't going to form in the first place.
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You did an excellent job of quickly and concisely explaining this relatively hard-to-digest theory. I can't imagine how it could have been explained more quickly or how it could have been explained in more depth or details in such a short time. Striking a balance between explaining the theory in enough depth to actually conceptualize it and not getting carried away with the details and complexities is not an easy thing to do, but you pulled it off superbly.
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Thanks, Arvin, for these kinds of videos. Explained wonderfully, and incredibly clear.
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Great explanation! What I find really helpful is to show the different levels of the strong force and interactions - from the strong force itself, thru the strong nuclear force to its effect on the stability of the atoms. I've always thought that unless you're going to the field professionally you most likely don't need all the math of these forces. For the ordinary people like me, what's the most important is to grasp the concept of the forces and interactions. And for that purpose videos like this are really priceless!
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This was a great video, I never grasped the difference between the strong force and strong nuclear force. Thank you!
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You got me subscribed. Awesome explanation. Elegant narration.
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Clearest explanation of basic QCD I've seen yet. Thank you!
