Among the bridges that I hope to build, as I develop this website, is one connecting what we know today about nature with how we know it. After all, you’re reading my depiction of nature, based on how I think nature works. I can try to assure you that my depiction is the mainstream viewpoint at the forefront of the research field — but you may still wonder if this website is legitimate, or if I might just be full of hot air, or if I might simply be mistaken. Well, my confidence in what I’m saying doesn’t come from having trained at some fancy university or my degree or from having been in the business for over 20 years. It comes from the data… in short, from nature itself.
So it’s important, I think, to link the data to the ideas and concepts, when it’s possible to do that.
You’ve heard the famous statement that “a proton is made from two up quarks and a down quark”. But in this basic article, and this somewhat more advanced one, and in Wednesday’s post where I went into some details about what we know about proton structure, I’ve claimed to you that protons are actually chock full of particles, most of which carry a tiny fraction of the proton’s energy, and most of which are gluons, with a lot of quarks and antiquarks. [If this sounds unfamiliar, you should read those articles and posts before reading this one, which is a follow-up.] And I claimed that these complications make a big difference at the Large Hadron Collider [LHC].
So should you take my word for this? You don’t have to. Let me show you evidence. From LHC data. Here’s an article defending the main claim’s of Wednesday’s post. It’s a near-final draft, still needing some proofreading perhaps, and probably some clarification, but I think it is fully readable now. Enjoy it (and please feel free to give me feedback on its clarity, so I can improve it), or wait for the final version next week, as you see fit. And have a great weekend!
8 Responses
The proton posts remind me I should give you some gentle encouragement to find the time to produce an article discussing the QCD vacuum. Not exactly an easy topic, but you’ve proved very good at explaining some very tricky concepts in modern physics to the lay level, so I’m sure if anyone can, it’s you.
Matt, I have just skimmed through the last few posts on the proton. Thank you for your energy and skill and kindness to your gentle readers. May I suggest a post title ? How about a salute to Dave Letterman entitled : The Top 10 Things You Need to Know About the Proton Collliding at the Large Hadron Collider. I can only hope that you will keep up the stellar work.
Hi Matt,
From someone with an undergraduate degree in physics…
My apologies if this has been asked before…
If a proton consists of “zillions” of quarks, then I would imagine its “boundary” would be a lot more poorly-defined than say, the wikipedia model of a proton as 3 quarks. I had previously imagined an atomic nucleus to be a seething froth of (distinct) protons, neutrons, and more tightly bound short-lived species such as alpha particles as per the diagram here:
http://en.wikipedia.org/wiki/Alpha_particle
But is this picture also incorrect? Is it better to also think of whole nucleii as “zillions” of quarks and gluons with some net (valence) number of up/down quarks?
And does this have anything to do with why neutrons are long-lived within nucleii?
Thanks a lot!
Answered here: http://profmattstrassler.com/2012/02/29/following-up-on-the-protons-structure/
So what about particles where the total number of quarks equals the total number of antiquarks? According to wikipedia, this is true of both a pi-0 and an eta meson, but the difference between the two is that the eta meson has a component of strange-antistrange whereas the pion is just an up-antiup or down-antidown. But if really all we can say about these mesons is they have equal numbers of quarks and antiquarks, then what’s the difference?
That is answered here: http://profmattstrassler.com/2012/02/29/following-up-on-the-protons-structure/
Matt, “ I can try to assure you that my depiction is the mainstream viewpoint at the forefront of the research field — but you may still wonder if this website is legitimate, or if I might just be full of hot air, or if I might simply be mistaken. Well, my confidence in what I’m saying doesn’t come from having trained at some fancy university or my degree or from having been in the business for over 20 years. It comes from the data… in short, from nature itself.”
My time is very valuable. Yet, I spend a lot of my valuable time reading Matt’s posts, simply because that his posts are very valuable and correct knowledge. Thanks Matt.
Matt has showed two facts about the proton structure.
1. The “internal” structure of proton is very complicated, and every proton has a different internal structure. Even the same proton has different internal structure, evolving in time.
2. All protons are identical for the external world.
These two facts can be written in simple mathematics forms. For zillions protons, P(1), P(2), …, P(n)… . n = zillions. The internal structure of P(1), …, P(n),… can be written as bellow.
P(1) ={ x1, y1, …, x2, y2, …}
P(2) = {a1, b1, …, a2, b2, …}
…
P(n) = {alpha1, beta1, … alpha2, beta2, …}
All their internal structures are different. Yet, P(1) = P(2) = … = P(n) = …. That is, all protons are identical regardless of their different internal structures. Mathematically, this fact is true if and only if { x1, y1, …, x2, y2, …, a1, b1, …, a2, b2, …, alpha1, beta1, … alpha2, beta2, …} arise from the same set of common denominator.
In the book “Linguistics Manifesto (ISBN 978-3-8383-9722-1)”, the infinite complexity can arise from a simple set with finite numbers of elements.
The more and more i think about quantum field theory the more excitation states of the vacuum that are interpreted as particles seem to me more like ripples on a differentiable manifold. If energy within a proton is not uniformly distributed this correct me if i am wrong could lead to different ripples being created and vanishing. Also for each moment in time due to different energy distributions we should get different spatial symmetries which are shown in different metrics, which lead to different possible space-time transformations(like the lorentz-transform for flat minkowski space). As i understand those transformations with different symmetries should actually lead to different particles since one would get a different hilbert space on which representations of symmetry groups of this space would be different than the representations of said symmetries on another hilbert space. one should get particles different than the ones on flat minkowski space. I am still trying to understand that so correct me if i am wrong. Shouldnt a full explanation of the inner workings a proton then only be possible if a full quantum understanding of the geometry of space is worked consistently into the formalism of QFT?