4 ms·

> Each neutron in an atomic nucleus is made up of three elementary particles called quarks. Well and tons and tons of virtual particles popping in and out of e

> Each neutron in an atomic nucleus is made up of three elementary particles called quarks. Well and tons and tons of virtual particles popping in and out of existance. Only a little over 1% the mass of a neutron is the three quarks normally listed.

tomrod 5y ago
I love that our fundamental reality is built on virtual particles. Physics rocks!
- JackFr 5y ago
  I love that our mental model of reality is built on virtual particles. Metaphysics rocks!
hongsy 5y ago
> Only a little over 1% the mass of a neutron is the three quarks normally listed. Do you have a source for this?
- monocasa 5y ago
  You can add up the mass of one up quark (2.2MeV) and two down quarks (4.7MeV each) and compare that to the mass of a neutron (939.565MeV)
- blobster 5y ago
  https://www.newscientist.com/article/dn16095-its-confirmed-matter-is-merely-vacuum-fluctuations/ https://www.newscientist.com/article/dn16095-its-confirmed-m...
- cwillu 5y ago
  https://profmattstrassler.com/articles-and-posts/particle-physics-basics/the-structure-of-matter/protons-and-neutrons/ https://profmattstrassler.com/articles-and-posts/particle-ph... has a very good explanation.
amerine 5y ago
Are virtual particles a real thing or just a description of the underlying system?
- monocasa 5y ago
  Just as real as the concepts of particles at all. They're just really likely to recombine because they form in pairs of opposite charges and will attract and annihilate. Hawking radiation is adding another force with a gradient (extremely strong gravity near an event horizon) that'll absorb one of the particles of the pair, and then the other flies off into space as the real, bona fide particle it always was.
- Fordec 5y ago
  Virtual particles are the universes equivalent of local variables inside a function. Parameters go in, results come out, but what stays in that local context still existed even if they didn't have global scope.
  - RosanaAnaDana 5y ago
    I realize the above is analogy, but can someone more informed than me confirm the correctness of the above description, because I find it to be a particular good one.
    - cwillu 5y ago
      I can think of some analogous ways to recover some semblance of the analogy, but it's not really a great one. A virtual "particle" is really more of a "disturbance" in a field: think splashing in a pool vs a wave. And in the context of the contents of a proton, imagine trying to differentiate a well-behaved 1hz wave from the other noise in the liquid, when the liquid is in a blender. edit to add: To recover the local/global variable analogy, imagine the compiler was continuously recompling the code based, inlining (or undoing that inlining), hoisting variables out of loops (or inserting them back), and trying to determine where a particular temporary value for calculation is being stored. Again, it's not a _great_ analogy; because I have a hard time determining how understanding the analogy would lead you to correct conclusions about virtual particles, but yeah.
kamaal 5y ago
>>Only a little over 1% the mass of a neutron is the three quarks normally listed. Pardon my layman ignorance. When the particles pop in and out of existence, how does mass manage to remain the same? Or does mass keep changing and is not fixed quantity but rather a range? And what do come out of, and where do they go?
- scotty79 5y ago
  The mass of the 99% comes from (kinetic?) energy that quarks have as the come together to from a neutron. This system has some energy like a rope moved by standing wave. Standing wave is a sum of waves traveling back and forth and sometimes adding up and sometimes cancelling each other into nothing. Gluons pop up out of nothing to carry this energy that struggling bound quarks have and add up into nothing passing their energy back to quarks. If you pump in even more energy into this system (for example by smashing something into it) even something like new quark-antiquark pair can pop up into existence and one of the original quarks might fly off away with one of the new particles to form a separate meson. The other particle from the created pair stays and changes the identity of three quark particle so it's no longer a neutron but some other three quark particle.
  - flqn 5y ago
    The mass comes from binding energy, not kinetic. The binding energy is potential energy in the gluons and their interactions with the quarks.
    - scotty79 5y ago
      Isn't binding energy, the energy released when things bind? And energy that has to be delivered to the system to break it apart? [1] The energy that is present withing the system of bound components must be something else. [1] https://en.wikipedia.org/wiki/Binding_energy https://en.wikipedia.org/wiki/Binding_energy
scotty79 5y ago
But the quarks give it it's identity. That's why they say it's made up from them, I assume.

tomrod 5y ago

I love that our fundamental reality is built on virtual particles. Physics rocks!

JackFr 5y ago
I love that our mental model of reality is built on virtual particles. Metaphysics rocks!

hongsy 5y ago

> Only a little over 1% the mass of a neutron is the three quarks normally listed. Do you have a source for this?

monocasa 5y ago
You can add up the mass of one up quark (2.2MeV) and two down quarks (4.7MeV each) and compare that to the mass of a neutron (939.565MeV)
blobster 5y ago
https://www.newscientist.com/article/dn16095-its-confirmed-matter-is-merely-vacuum-fluctuations/ https://www.newscientist.com/article/dn16095-its-confirmed-m...
cwillu 5y ago
https://profmattstrassler.com/articles-and-posts/particle-physics-basics/the-structure-of-matter/protons-and-neutrons/ https://profmattstrassler.com/articles-and-posts/particle-ph... has a very good explanation.

amerine 5y ago

Are virtual particles a real thing or just a description of the underlying system?

monocasa 5y ago
Just as real as the concepts of particles at all. They're just really likely to recombine because they form in pairs of opposite charges and will attract and annihilate. Hawking radiation is adding another force with a gradient (extremely strong gravity near an event horizon) that'll absorb one of the particles of the pair, and then the other flies off into space as the real, bona fide particle it always was.
Fordec 5y ago
Virtual particles are the universes equivalent of local variables inside a function. Parameters go in, results come out, but what stays in that local context still existed even if they didn't have global scope.
- RosanaAnaDana 5y ago
  I realize the above is analogy, but can someone more informed than me confirm the correctness of the above description, because I find it to be a particular good one.
  - cwillu 5y ago
    I can think of some analogous ways to recover some semblance of the analogy, but it's not really a great one. A virtual "particle" is really more of a "disturbance" in a field: think splashing in a pool vs a wave. And in the context of the contents of a proton, imagine trying to differentiate a well-behaved 1hz wave from the other noise in the liquid, when the liquid is in a blender. edit to add: To recover the local/global variable analogy, imagine the compiler was continuously recompling the code based, inlining (or undoing that inlining), hoisting variables out of loops (or inserting them back), and trying to determine where a particular temporary value for calculation is being stored. Again, it's not a _great_ analogy; because I have a hard time determining how understanding the analogy would lead you to correct conclusions about virtual particles, but yeah.

kamaal 5y ago

>>Only a little over 1% the mass of a neutron is the three quarks normally listed. Pardon my layman ignorance. When the particles pop in and out of existence, how does mass manage to remain the same? Or does mass keep changing and is not fixed quantity but rather a range? And what do come out of, and where do they go?

scotty79 5y ago
The mass of the 99% comes from (kinetic?) energy that quarks have as the come together to from a neutron. This system has some energy like a rope moved by standing wave. Standing wave is a sum of waves traveling back and forth and sometimes adding up and sometimes cancelling each other into nothing. Gluons pop up out of nothing to carry this energy that struggling bound quarks have and add up into nothing passing their energy back to quarks. If you pump in even more energy into this system (for example by smashing something into it) even something like new quark-antiquark pair can pop up into existence and one of the original quarks might fly off away with one of the new particles to form a separate meson. The other particle from the created pair stays and changes the identity of three quark particle so it's no longer a neutron but some other three quark particle.
- flqn 5y ago
  The mass comes from binding energy, not kinetic. The binding energy is potential energy in the gluons and their interactions with the quarks.
  - scotty79 5y ago
    Isn't binding energy, the energy released when things bind? And energy that has to be delivered to the system to break it apart? [1] The energy that is present withing the system of bound components must be something else. [1] https://en.wikipedia.org/wiki/Binding_energy https://en.wikipedia.org/wiki/Binding_energy

scotty79 5y ago

But the quarks give it it's identity. That's why they say it's made up from them, I assume.