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Protons Aren't round
drox writes "USA Today reports that protons are ovoid rather than spherical, as most of us learned in school." In related news, thousands of high school science labs have thrown out a bunch of little plastic balls.
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...USA Today, the newspaper that specializes in boiling down complex issues into six sentences, knows anything about physics. Yeah, um... right.
...can I still sprinkle them on my cheerios for my morning breakfast?
They ain't teachin' you nothin' at that damn school. Pie are round! Cornbread are squared.
How ya like dat?
Protons are at the core of our understanding of reality.
Surely their shape counts?
Yours Sincerely, Michael.
As the protons are moving at such high speeds in the nucleus (disregarding for the moment the fact that their speed and location are rather hard to determine exactly), this is an expected result.
Why? Relativity. Objects moving at high speeds appear contracted along the axis of their movement to observers in a "fixed" reference frame.
No surprises here, move on, move on...
TANSTAAFI: There Ain't No Such Thing As A Free iPod.
How can a proton have definate (or semi definate) shape? Shape can only be observed by sight (and protons are much smaller than the wavelength of light and don't just bounce high energy electo-magentic radiation), or by collision. Protons do not collide in the normal way, they either repulse like-charged particles by the electroweak force or attract them. So, how can the shape have any meaning?
how do 3 small objects (quarks) that are presumably the same shape (or at least 2, up up down...) make up a larger object thats ovoid? i realy don't think subatomic particles can ever be given a definite shape, heisenberg anyone, can we actually observe the shape or orbit(do they orbit?) of quarks?
"Sic Semper Tyrannosaurus Rex."
Protons are made up of only three quarks. Of course they'd be a little misshapen. Find me a subnuclear particle with four or six quarks, then I'll surprised to find out it's not a perfect sphere.
Matthew G P Coe
http://mgpcoe.blogspot.com/
I have a paper from Hendrik Schon here that says they're shaped like tiny little cheddar cheese goldfish. Who would you believe, USA Today or Bell Labs?
"The new thing we've figured out is that quarks are moving around inside the proton at relativistic (near speed of light) speeds,"
They are saying that an object with mass is moving around inside the proton at near light speed.
That would mean the proton's mass is near infinite, which is clearly not the case.
As you can see from the comma after the quote, this was a quote taken out of context which distorted any meaning this story might have had.
USA today has always had crap science reporting.
If voting were effective, it would be illegal by now.
In the article it said quarks travel at around ninety percent of the speed of light. So, tell you what, let's compute just how much more massive those quarks are. Fire up your LISP interpreter. We're taking a trip into Mathemagicland.
.9)
In LISP notation...
(defun relativistic-mass (m v) (/ m (sqrt (- 1 (/ (* v v) 1)))))
(relativistic-mass 1
2.294157
... So as you can tell, relativity tells us that at ninety percent of c, an object is only going to have two and a quarter times its normal mass. I don't see how you come up with the notion that "if the quarks are traveling relativistically, then the proton's mass must be near-infinite, thus quarks aren't traveling relativistically". If anything, your science is just as much junk as the USA Today article you're blasting.
The implication that the proton doesnt have three radial symmetries is pretty sweet - we now _know_ that the proton can support two axes of rotation, meaning that they can store rotational energy, that we could only assume if protons were perfectly radially symmetric (and therefore completely indistinguishable from their non-rotating kin). This has thermodynamic implications, the degrees of freedom are increased if the proton can store rotational quanta, and possibly increasing our understanding of plasmas. How can any right-thinking geek find this banal?
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It's funny how little bits of misinformation become "common knowledge". The solar system model of atomic structure was shot down almost a century ago, but the picture of a bunch of electrons orbiting a clump of protons and neutrons is still the picture most people conjur up when you say "atom". Other examples: "Columbus proved the earth was round" (astronomers did this centuries before, and even measured the diameter of the planet, of which data Columbus was quite ignorant); "Lindbergh was the first pilot to fly solo accross the Atlantic" (technically true, but it's sad that people think an aviation pioneer is famous simply for going without sleep for 36 hours). Etc., etc.
Why have they departed from the industry standard spherical cow?
This appears to be the abstract for the announced results. Note the lack of words like "round" in the abstract and article. You may need a subscription to Physical Review Letters to reach it and download the paper.
This appears to be the abstract of the paper of Miller and Frank attempting to explain the phenomena. You will have to accept cookies to get any sort of information out of the APS site.
This seems to be the experimental project page. It doesn't appear to be an informative resource for the uninitiated.
I'd never read a nuclear physics paper before, so I wasn't sure what to expect. It looks like straight pQFT calculation with the Feynman diagrams, etc. would be computationally intractible for these problems, so people are always looking for reasonable approximation schemes. I guess the ones that had been used in the past didn't factor in relativistic effects as much as they should have, and the recent models corrected this.
"Your notation sucks!" -- Serge Lang (1927-2005)
A number of comments posted here are mistaken about the nature of shape in the quantum world. It has nothing to do with the probability distribution of the proton's location; it has to do with the probability distributions of the quarks within the proton.
Only entities that are extended in space have shape. Electrons, for example, are to the best of our knowledge pointlike, and therefore we say they do not have shape. Atoms, on the other hand, are extended in space and therefore do have shape. Their shape is given to them by the probability distributions for the locations of the electrons that surround them, not by the probability distribution of their own location.
Shape is described in nuclear physics using the mathematical device of the "structure function", which is just a function of the three spatial co-ordinates that describes the size and (a)symmetries of the nucleus relative to some interaction. Structure functions are ususally expressed as linearly weighted sums of spherical harmonics or Legendre polynomials, which capture physically interesting processes in different terms.
Protons are believed to have a spherically symmetric structure function. On a number of both theoretical and experimental grounds I'd be extremely doubtful that the dynamical structure function of the proton is asymmetric, and the article in fact suggests that the result is a purely kinematic one due to relativistic effects, which is suprising but in the final analysis not the kind of earth-shattering news dynamical asymmetry would be.
In particular, a dynamical asymmetry of the proton would imply naively a comparable asymmetry of the neutron, and this is known not to exist experimentally at very high precision (and whose existence at a very small level is predicted by electro-weak theory.)
--Tom
Blasphemy is a human right. Blasphemophobia kills.
This is good. It means they won't roll off the glass slide when they study them under microscopes.
Physicists hate it when that happens.
Table-ized A.I.