5 ms·

What's inside a proton?

62 points by georgecmu 13y ago

acqq 13y ago
The best answer is from David Z, which is still not the top one.
- deleted 13y ago
  [deleted]
  - acqq 13y ago
    Did you read the whole answer? Did you compare it with the other answers? Compared to them David's is actually exactly in line with the goals you state.
    - deleted 13y ago
      [deleted]
- yk 13y ago
  The deleted answer was actually a great point, it was basically a nitpick on the first sentence of David Z's answer. A proton is really made of quantum fields. The problem with this statement is, that a observed object is said to be made of a mathematical abstraction. So in a way, this is saying that a raytracer is made of C. If we look into the ELF binary, we will find shell code, if we look at the computer very closely we will find electrical signals, but we will only find C in the reverse engineered source code. So similarly, the statement should probably read: A proton is described as made of quantum fields. However, it is still important to remind everybody, that the popular analogy of high energy physics, particles which interact much like billiard balls, is a somewhat leaky abstraction. And this question is probably more a expression of this leaking than a question of fundamental physics. If we would make the classical analogy, that a proton is (described as) a stable field configuration, then we would probably not have the question.
  - acqq 13y ago
    So you also effectively acknowledge the content of the whole David's answer. The nitpicking point is just the very first sentence, not anything material in the answer, and only that he wrote "is really made of" instead of "is currently best described as made of." Nitpicking indeed, and irrelevant to anybody reading the whole answer and comparing it with the rest. Because he explicitly shows what and how we are now able to observe, compute and predict. It's the others that present the topic in absolutes. Once we accept the basic staring point that physics is the loop in which we do the experiments, refine the models, then refine the experiments, etc, we simply don't need to insist on disclaimers that we do it that that way in every our statement. Most of the other answers come from the previous iterations of the described loop, David's from the more recent.
    - yk 13y ago
      Yes, it is a great answer. But someone did make this point, and deleted his comment. And I thought, that this is a interesting detail, which should not be lost for the discussion. Edit:Grammar.
      - diminish 13y ago
        sorry for deleting the comment, liked David Z's answer but got downvoted heavily, so i didn't want to bother this thread with philosophical discussions. But now after seeing further discussions half a day later, I think I did wrong. So thanks for great discussions. i was pointing out a problem you may read in feynman's and gerard 't hooft's writings and early quantum physicists, when it comes to interpreting quantum phenomena. What is is? do Mathematical entities have outside existence? Kant, Brentano, Frege, Heidegger, empiricists also touched this issue. ps: I'm a physics graduate and studied/did lab work with CERN neutrino oscillation researchers, so I like such discussions wherever they pop up.
  - frozenport 13y ago
    >>So in a way, this is saying that a raytracer is made of C? Yes, but isn't it? >>The problem with this statement is, that a observed object is said to be made of a mathematical abstraction. These fields are very real, it is our understanding of them that is perhaps inaccurate!
elux 13y ago
You may have heard that a proton is made from three quarks. Indeed here are several pages that say so. This is a lie — a white lie, but a big one. In fact there are zillions of gluons, antiquarks, and quarks in a proton. The standard shorthand, “the proton is made from two up quarks and one down quark”, is really a statement that the proton has two more up quarks than up antiquarks, and one more down quark than down antiquarks. To make the glib shorthand correct you need to add the phrase “plus zillions of gluons and zillions of quark-antiquark pairs.” Without this phrase, one’s view of the proton is so simplistic that it is not possible to understand the LHC at all. http://profmattstrassler.com/articles-and-posts/largehadroncolliderfaq/whats-a-proton-anyway/ http://profmattstrassler.com/articles-and-posts/largehadronc...
mladenkovacevic 13y ago
I've been having discussions about this with my brother about this recently (who is a million times smarter than me) and it's remarkable to me that all throughout school we think of matter at real, solid stuff we see around us while subatomic particles are virtual abstractions used to describe the solid, real stuff. I never could've understood quantum field theory in those days (and still probably don't for the most part), but from what I do understand it's turned my previous "knowledge" upside down - EVERYTHING is made up of fields or pure mathematical structures, even the empty space around us, and it's the matter and particles which we can see and feel that is a virtual abstraction made up of those fields.
- agumonkey 13y ago
  I recently came to this point of view. What surprised me is how much more natural and organic fields feel to me. Much much closer to our perception of the world than some geometrical abstraction you start with. Almost wish school taught that first.
SaberTail 13y ago
One of my professors was fond of saying, "the proton is a garbage dump," to emphasize the mess of gluons and virtual quarks that you see when you start to probe the proton. It's also worth noting that the in the LHC, which collides protons, most of the interesting collisions are due to gluons interacting, rather than the quarks.

62 points by georgecmu 13y ago

acqq 13y ago

The best answer is from David Z, which is still not the top one.

deleted 13y ago
[deleted]
- acqq 13y ago
  Did you read the whole answer? Did you compare it with the other answers? Compared to them David's is actually exactly in line with the goals you state.
  - deleted 13y ago
    [deleted]
yk 13y ago
The deleted answer was actually a great point, it was basically a nitpick on the first sentence of David Z's answer. A proton is really made of quantum fields. The problem with this statement is, that a observed object is said to be made of a mathematical abstraction. So in a way, this is saying that a raytracer is made of C. If we look into the ELF binary, we will find shell code, if we look at the computer very closely we will find electrical signals, but we will only find C in the reverse engineered source code. So similarly, the statement should probably read: A proton is described as made of quantum fields. However, it is still important to remind everybody, that the popular analogy of high energy physics, particles which interact much like billiard balls, is a somewhat leaky abstraction. And this question is probably more a expression of this leaking than a question of fundamental physics. If we would make the classical analogy, that a proton is (described as) a stable field configuration, then we would probably not have the question.
- acqq 13y ago
  So you also effectively acknowledge the content of the whole David's answer. The nitpicking point is just the very first sentence, not anything material in the answer, and only that he wrote "is really made of" instead of "is currently best described as made of." Nitpicking indeed, and irrelevant to anybody reading the whole answer and comparing it with the rest. Because he explicitly shows what and how we are now able to observe, compute and predict. It's the others that present the topic in absolutes. Once we accept the basic staring point that physics is the loop in which we do the experiments, refine the models, then refine the experiments, etc, we simply don't need to insist on disclaimers that we do it that that way in every our statement. Most of the other answers come from the previous iterations of the described loop, David's from the more recent.
  - yk 13y ago
    Yes, it is a great answer. But someone did make this point, and deleted his comment. And I thought, that this is a interesting detail, which should not be lost for the discussion. Edit:Grammar.
    - diminish 13y ago
      sorry for deleting the comment, liked David Z's answer but got downvoted heavily, so i didn't want to bother this thread with philosophical discussions. But now after seeing further discussions half a day later, I think I did wrong. So thanks for great discussions. i was pointing out a problem you may read in feynman's and gerard 't hooft's writings and early quantum physicists, when it comes to interpreting quantum phenomena. What is is? do Mathematical entities have outside existence? Kant, Brentano, Frege, Heidegger, empiricists also touched this issue. ps: I'm a physics graduate and studied/did lab work with CERN neutrino oscillation researchers, so I like such discussions wherever they pop up.
- frozenport 13y ago
  >>So in a way, this is saying that a raytracer is made of C? Yes, but isn't it? >>The problem with this statement is, that a observed object is said to be made of a mathematical abstraction. These fields are very real, it is our understanding of them that is perhaps inaccurate!

elux 13y ago

You may have heard that a proton is made from three quarks. Indeed here are several pages that say so. This is a lie — a white lie, but a big one. In fact there are zillions of gluons, antiquarks, and quarks in a proton. The standard shorthand, “the proton is made from two up quarks and one down quark”, is really a statement that the proton has two more up quarks than up antiquarks, and one more down quark than down antiquarks. To make the glib shorthand correct you need to add the phrase “plus zillions of gluons and zillions of quark-antiquark pairs.” Without this phrase, one’s view of the proton is so simplistic that it is not possible to understand the LHC at all. http://profmattstrassler.com/articles-and-posts/largehadroncolliderfaq/whats-a-proton-anyway/ http://profmattstrassler.com/articles-and-posts/largehadronc...

mladenkovacevic 13y ago

I've been having discussions about this with my brother about this recently (who is a million times smarter than me) and it's remarkable to me that all throughout school we think of matter at real, solid stuff we see around us while subatomic particles are virtual abstractions used to describe the solid, real stuff. I never could've understood quantum field theory in those days (and still probably don't for the most part), but from what I do understand it's turned my previous "knowledge" upside down - EVERYTHING is made up of fields or pure mathematical structures, even the empty space around us, and it's the matter and particles which we can see and feel that is a virtual abstraction made up of those fields.

agumonkey 13y ago
I recently came to this point of view. What surprised me is how much more natural and organic fields feel to me. Much much closer to our perception of the world than some geometrical abstraction you start with. Almost wish school taught that first.

SaberTail 13y ago

One of my professors was fond of saying, "the proton is a garbage dump," to emphasize the mess of gluons and virtual quarks that you see when you start to probe the proton. It's also worth noting that the in the LHC, which collides protons, most of the interesting collisions are due to gluons interacting, rather than the quarks.