Physicists find that an ultrahigh-energy proton looks like a black disk

Dec 08, 2011 by Lisa Zyga feature
This figure shows two protons crossing each other at the LHC at an impact parameter, b. Because of their velocity near the speed of light, the protons are contracted to thin disks. An analysis of the proton-proton cross section suggests that high-energy protons are black disks. Image credit: LHC

(PhysOrg.com) -- What does a proton look like? The common answer to this question is that protons are much too small to scatter light, and since light is necessary for us to see things, protons do not “look” like anything. But in a new study, physicists have gathered sufficient evidence to show that, at least at very high energies, the proton is a black disk – sort of an elongated hockey puck. This description fits only for protons at such ultrahigh energies that even the most advanced experiments will probably never be able to detect them.

The physicists, Martin Block, Professor Emeritus at Northwestern University in Evanston, Illinois, and Francis Halzen, Physics Professor at the University of Wisconsin in Madison, Wisconsin, have published their analysis of the proton in a recent issue of Physical Review Letters.

As every student learns in physics class, a proton is a very small (about 1.6 femtometers [10-15 meters] in diameter) positively charged subatomic particle found in the nucleus of an atom. A proton is made of two “up” quarks and one “down” quark. The three quarks are held together by the strong force, which is mediated by other particles called gluons. A lot of activity goes on inside a proton: quarks bounce around and exchange gluons, and virtual particle-antiparticle pairs constantly pop in and out of the vacuum. When accounting for these complex dynamics, and also that the wave-particle duality of quantum mechanics postulates that protons have properties of both waves and particles, visualizing a proton is not a simple matter.

However, thanks to relativity, physicists have some hints of what a proton should theoretically look like when its velocity approaches the speed of light. Due to Lorentz contraction, the proton should contract into a disk with no thickness, or in other words, a two-dimensional disk. This shape is due completely to relativity, and has nothing to do with the interactions between quarks, gluons, etc., which are instead described by quantum chromodynamics.

In their study, Block and Halzen have now discovered that this disk is likely black. To reach this conclusion, they analyzed the results of three different experiments and developed their own numerical model that is completely independent of the experimental data in order to try to get a better glimpse of the proton’s structure. These investigations involve determining what happens when two protons interact, which occurs when physicists accelerate one proton to very high energies and “shoot” it at a second proton.

“In our model, at least asymptotically [i.e., as the proton’s energy approaches infinity], a proton will scatter any particle (for instance another proton) like a billiard ball half of the time (elastic collision) and totally absorb it the other half of the time (inelastic collision),” Halzen told PhysOrg.com. Such behavior is very similar to the way a black disk should behave.

Physicists have been investigating proton-proton collisions for several decades. By calculating the fraction (or cross section) of proton-proton inelastic scattering processes and comparing it to the proton-proton total (elastic plus inelastic) cross section, researchers have gained a better understanding of the inner structure of protons. (Scientists have been investigating the growth of the proton-proton total cross section ever since it was discovered in the early 1970s by a team at CERN, of which Block was a member early in his career.)

In this study, Block and Halzen analyzed measurements of the inelastic and total cross sections that were recently taken at two different energies by three independent experiments. At an energy of 7000 GeV, the Atlas collaboration measured an inelastic cross section of 69.1 millibarn (a millibarn [mb] is an area equal to 10-27 cm2), and the CMS collaboration used a completely different technique to measure it at a compatible 68 mb. At 57,000 GeV, the Pierre Auger Observatory collaboration used cosmic ray measurements to calculate an inelastic cross section of 90 mb. For comparison, Block and Halzen’s purely numerical calculations predict inelastic cross sections of 69.0 mb at 7000 GeV and 92.9 mb at 57,000 GeV, both of which agree closely with the experimental data.

Block and Halzen also explain that 57,000 GeV is likely the highest energy at which such experiments can be performed, making it as close to asymptopia (defined here as the behavior of the cross section as the energy level approaches infinity) as scientists will ever get. However, the experimental measurements are still quite far from asymptopia.

Yet in spite of these limitations, the data do provide some evidence of how the inelastic and total cross sections behave when the energy approaches infinity. When combining the experimental measurements with the predictions of their purely numerical approach, Block and Halzen found that, as the energy increases to infinity, the ratio of the inelastic cross section to the total cross section is about 0.509. In other words, an asymptotic proton scatters another proton half the time and absorbs it half the time.

Interestingly, the predicted ratio of the inelastic cross section to the total cross section for a black disk is 0.5, which agrees with Block and Halzen’s result for the asymptotic proton, within measurement error. For this reason, the new findings provide the first experimental evidence that a proton becomes a black disk as its energy approaches asymptopia.

The physicists’ model provides some further details about the asymptotic proton in terms of quantum chromodynamics. The scientists explain that, at ultrahigh energies, the structure is totally dominated by the gluons instead of quarks. In contrast, at sub-asymptotic energies, the quarks play a more significant role and there aren’t enough gluon constituents to form a shape that is totally black or a complete two-dimensional disk. The scientists’ model even predicts the mass of the lightest particle state made from gluons, dubbed the glueball. This clue to the glueball’s mass may aid in the search for glueballs, which has been a challenging goal of several experiments. In addition, the physicists’ calculations predict that the black disk is expanding, which is in accordance with very general theoretic predictions from the 1960s.

Even though the ultrahigh energy of asymptotic protons makes it unlikely for them to be produced in experiments, the scientists say it’s possible that these highly energetic protons do exist in nature.

“Asymptotic protons may exist as cosmic rays but with a tiny flux that even large air shower arrays such as Auger are insensitive to,” Halzen said. “Maybe someday we will develop cosmic ray detection techniques that will give us access to data at yet higher energies.”

He added that understanding proton-proton interactions not only reveals hints of what high-energy protons look like, but it may also help scientists in their research.

“[The proton-proton total cross section] value at very high energies is one of the ingredients for extracting physics from cosmic ray experiments such as Auger and the Telescope Array,” he said. “In that sense, our work has also some more practical value.”

Explore further: Uncovering the forbidden side of molecules

More information: Martin M. Block and Francis Halzen. “Experimental Confirmation that the Proton is Asymptotically a Black Disk.” PRL 107, 212002 (2011). DOI: 10.1103/PhysRevLett.107.212002

Journal reference: Physical Review Letters search and more info website

4.5 /5 (24 votes)

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rawa1
1.1 / 5 (29) Dec 08, 2011
From dense aether theory follows, the fast moving particles are surrounded with wake wave (area of more dense vacuum foam oriented perpendicularly to the particle motion direction), which adjusts the speed of light in such a way, the speed of light perceived remains constant for external observer.

http://media.phot...peed.gif

It's example of phenomena, which demonstrates, how the quantum mechanics effect (i.e. the de Broglie wave) plays well with special relativity (i.e. invariance of the speed of light postulate). In general, the relativistic contraction can be modelled with shortening of the wave wave even at the water surface.

shttp://www.aether...boat.gif
ScienceFreak86
3.8 / 5 (14) Dec 08, 2011
"that even the most advanced experiments will probably never be able to detect them" really? even in 3000? I think we will achieve this even in this century.

They are so closeminded...they think, that we know everything, we are just beginning to develop "advanced technologies"
vlaaing peerd
3.6 / 5 (9) Dec 08, 2011
if a proton is too small to reflect light anyway, wouldn't it be black in the first place?
rawa1
1.6 / 5 (13) Dec 08, 2011
"that even the most advanced experiments will probably never be able to detect them" really? even in 3000? I think we will achieve this even in this century.

They are so closeminded...they think, that we know everything, we are just beginning to develop "advanced technologies"

We already detected such a particles many times... The record holder is a proton of energy 3E10 20 eV, i.e. 3 000 000 000 000 GeV i.e. 52 millions times higher, than the energy limit 57,000 GeV presented in the article

http://en.wikiped...smic_ray
Nanobanano
1.6 / 5 (14) Dec 08, 2011
Isn't it pretty obvious that in Relativity anything with an asymptopic velocity would eventually become a black hole due to the relativity of mass?

Even if you ignore length contraction, if the velocity approaches c, then the relativistic mass approaches infinity. At some point this would obtain a density high enough to have an event horizon.

Yet likewise, if you ignore relativity of mass, then length contraction causes the length to approach 0 as velocity approaches c, and again, density eventually becomes high enough to have an event horizon.
sstritt
4.7 / 5 (12) Dec 08, 2011
Even if you ignore length contraction, if the velocity approaches c, then the relativistic mass approaches infinity. At some point this would obtain a density high enough to have an event horizon.

No. Relativistic mass is not the same as inertial mass. There would be no event horizon.
rawa1
1.4 / 5 (20) Dec 08, 2011
No. Relativistic mass is not the same as inertial mass. There would be no event horizon.
This is easy to say, but it may be not so easy to explain it. Why? For example, the physicists are using relativistic mass routinely, when explain the gain of mass at the case of heavy electrons around atom nuclei. In this case they're handling it like the real mass, which increases the weight of atoms in ponderable way.

http://physics.ap.../v27/st2

So, for every such a claim I can bring another example, which is demonstrating, that the relativistic mass is real mass, not just abstract artefact of some equations. Fortunately, thanks to dense aether model we can imagine the real situation with protons by now. The fast electrons or protons gain their mass with covering itself with dense vacuum foam like the snowball with snow. So that the relativistic mass increases the size of particle - not its density and the black hole can not be formed.
KBK
4.8 / 5 (17) Dec 08, 2011
As my physics teacher used to say as he was drawing on the board.. 'everybody knows that electrons are blue'.

And the 19 year old students would simultaneously dig furiously though their pencil cases for a blue pencil... to get their diagrams correct.
rawa1
2.2 / 5 (13) Dec 08, 2011
It's the similar stuff, like to say, electrons are of negative charge. Their charge is just opposite to proton's one - everything else is just a convention. We really don't know, which charge the electron is of - we just postulated it so..
dtyarbrough
1.4 / 5 (11) Dec 08, 2011
Velocity of individual particles reduces their spin, reducing their magnetic fields and thus their physical mass. This is why a photon traveling at the speed of light does not gain infinite mass. (Conservation of energy) Spin and speed are inversely proportional.
rowbyme
4.7 / 5 (21) Dec 08, 2011
Thanks for the insight Rawa 1. It's a shame we humans spend billions of dollars on physics research, like building the LHC for instance, when all the scientific community had to do was email you for all the answers.
Pyle
3.8 / 5 (6) Dec 08, 2011
if a proton is too small to reflect light anyway, wouldn't it be black in the first place?
No, not black. Maybe transparent would be closer to the point, but only if you can't wrap your mind around the more correctly worded, "too small to reflect light".

QC: You are forgetting that GR is WRONG when you get down to things of this size. GR is a point particle model and it just doesn't work. By the same token, neither does QM. M-theory doesn't work yet because we don't have it nailed down yet. Let's just say that I have a feeling that modeling asymptotic protons is probably violating some underlying implicit assumption of GR. Kind of like using perturbative methods in string theory when the coupling constant gets large.

(hehe, couldn't think of a good analogy to convey my point so I made it worse.)
CHollman82
4.3 / 5 (6) Dec 08, 2011
I read the last word of the article title wrong and almost busted out laughing at work...
rawa1
1.5 / 5 (15) Dec 08, 2011
It's a shame we humans spend billions of dollars on physics research, like building the LHC for instance, when all the scientific community had to do was email you for all the answers.
Why do you think so? The scientists are just doing their very best for neverending business. They never forget to check the most natural solution just at the very end, when all other options are exhausted. It's just the layman public, who is willing to pay these smartasses from public money and who is serving as a marvellous donkey whose droppin's are gold..
ED__269_
1 / 5 (1) Dec 08, 2011
The bottom line is, its only an idea.

Callippo
1.2 / 5 (11) Dec 08, 2011
Concept of de Broglie wave is pretty old and well elaborated. After all, string theory is just an idea too. But it can feed many mathematicians, so they're keeping it alive. Nobody cares about ideas, which are too transparent for to prohibit the public feedback. From the same reason the medieval shamans kept their silly rituals in secret.
Graeme
not rated yet Dec 08, 2011
>if a proton is too small to reflect light anyway, wouldn't it be black

If it was like this it would be transparent. However if you consider other fast moving reference frames, the light will be seriously blue shifted into gamma ray energies and the proton will do something with that if it is high energy enough.
qitana
not rated yet Dec 09, 2011
would this mean that the quarks in this proton are further from each other (because of the elongation of the proton) ?

and if so, would this mean that the proton would be less stable?

and if so, would this mean that at even higher energies, the proton could not exist any more or only for a very short time?

I find these thoughts interesting, so i'd like to share them with you

perhaps some of you know the answers
DavidMcC
5 / 5 (6) Dec 09, 2011
"if a proton is too small to reflect light anyway, wouldn't it be black in the first place?"

I strongly suspect that the researchers were using the word "black" to mean that the proton-proton interaction cross-section was equal to its geometrical value. This has nothing to do with interactions with photons, it's just a way of expressing the proton interaction. I also suspect that the physorg reporter did not notice this.
dtyarbrough
1.8 / 5 (15) Dec 09, 2011
Photons are not all the same size. The physical diameter of their magnetic fields is the socalled wavelength of the photon. Infrared photons are billions of time larger than gamma or x-ray photons. Photons are not waves and radio waves and longer wavelengths are not photons. When medical researchers find a cure for cranial rectulitus, physicists will be able to get the heads out of their butts and see this.
Occupodies
3 / 5 (6) Dec 09, 2011
Photons are not all the same size. The physical diameter of their magnetic fields is the socalled wavelength of the photon. Infrared photons are billions of time larger than gamma or x-ray photons. Photons are not waves and radio waves and longer wavelengths are not photons. When medical researchers find a cure for cranial rectulitus, physicists will be able to get the heads out of their butts and see this.

... Are you retarded? ... Wiki Maxwell's equations, then DIAF. Also... radio, micro, visual spectrum, etc. are all em waves... you should stop posting.
Callippo
1.6 / 5 (5) Dec 09, 2011
Photons aren't waves but a (quantum) wave packets. And dtyarbrough is right, their size depends on the wavelength of light, which is actually quite trivial to understand.

http://www.aether...tons.gif
BIG COCK
5 / 5 (9) Dec 09, 2011
Concept of de Broglie wave is pretty old and well elaborated. After all, string theory is just an idea too. But it can feed many mathematicians, so they're keeping it alive. Nobody cares about ideas, which are too transparent for to prohibit the public feedback. From the same reason the medieval shamans kept their silly rituals in secret.


Have you ever considered that maybe you're just stupid and they're not?
Shelgeyr
1 / 5 (6) Dec 09, 2011
physicists have gathered sufficient evidence (snip)... This description fits only for protons at such ultrahigh energies that even the most advanced experiments will probably never be able to detect them.


Waitwhat? Didn't this say "gathered sufficient evidence..."?

...the proton should contract into a disk with no thickness, or in other words, a two-dimensional disk.


Nonsense. And yes, I know it is "relativity". I just bet they're either multiplying by infinity, or dividing by zero again.

...have now discovered that this disk is likely black. To reach this conclusion...


Wait... Did they "discover" something or did they just reach a conclusion?

In our model, at least asymptotically (i.e., as the proton's energy approaches infinity),


BINGO! Nothing to see here folks... Once again results of a model are mistakenly taken as "evidence", AND their conclusion is based on an irrational limit, that being a proton with infinite energy. Sigh.
Vendicar_Decarian
0.3 / 5 (36) Dec 10, 2011
"Such behavior is very similar to the way a black disk should behave." - Article

A completely black disk won't scatter anything. Neither will it radiate anything.

So what are these protons radiating in order to compensate for the 50 percent of the photons that they are absorbing?

Vendicar_Decarian
0.6 / 5 (38) Dec 10, 2011
"Even if you ignore length contraction, if the velocity approaches c, then the relativistic mass approaches infinity. At some point this would obtain a density high enough to have an event horizon." - Nano

This is incorrect.

The rules of physics are the same for every observer, and every observer must agree on the outcome of an experiment. Hence the trajectories of particles near a sphere moving near c will be no different than the trajectories of those particles as seen in the reference frame of the moving sphere, corrected for dilation.

Since the sphere is not a black hole in it's own reference frame it can't be one in any other reference frame.

You may interpret this as an additional requirement for a black hole to form that is a function of it's velocity from an observer if you like.

Or you can compute the stress energy tensor of it's gravitational field and find that momentum is one component. Not mass.

Rohitasch
1 / 5 (1) Dec 11, 2011
if a proton is too small to reflect light anyway, wouldn't it be black in the first place?

if a proton is too small to reflect light anyway, wouldn't it be black in the first place?

To be black, it has to absorb light. But since it is so damn tiny, light just misses it. So as afar as the visible and UV spectrum is concerned, the proton simply "isn't there" and not black.
Rohitasch
2.5 / 5 (2) Dec 11, 2011
would this mean that the quarks in this proton are further from each other (because of the elongation of the proton) ?

and if so, would this mean that the proton would be less stable?

and if so, would this mean that at even higher energies, the proton could not exist any more or only for a very short time?

I find these thoughts interesting, so i'd like to share them with you

perhaps some of you know the answers

These protons are in a different frame of reference. In their own frame they are not flat themselves but the length of the tunnel they are being accelerated in is equally short. In the lab frame, they are flat but their time is also dilated by the same amount so eve if they were unstable particles (instead of stable protons), they would be relatively more stable (their clocks tick slower). The contraction seen is only in the direction of motion. So they don't actually spread out like a pizza.
Callippo
1 / 5 (3) Dec 11, 2011
The contraction seen is only in the direction of motion.
This is what bother me. If we would keep a pair of mutually perpendicular laser clocks at the reference frame of protons, wouldn't their speed differ after while?
Vendicar_Decarian
0.3 / 5 (36) Dec 11, 2011
"But since it is so damn tiny, light just misses it" - Roh

Tell that to a Gamma Ray photon.
Vendicar_Decarian
0.2 / 5 (35) Dec 11, 2011
The spherical symmetry of a proton becomes the symmetry of an oblate spheroid when the proton has motion relative to an observer.

The entire charge field of proton is altered in the same manner so that the boundary of constant potential becomes oblate as well.

Therefore objects in front or behind the proton that would normally experience a force F will appear to experience a force f, and the difference F minus f is attributed to something called magnetism. A force that does not really exist in nature.
Callippo
1 / 5 (5) Dec 11, 2011
"But since it is so damn tiny, light just misses it" Tell that to a Gamma Ray photon.
This is interesting stuff too - because the atom nuclei are so small, there should be apparently lower absorbance of light with gamma rays with compare to visible light. Because the probability of hitting of small object is significantly lower than the probability of hitting the larger one.. The AWT explains it with large bulky blob of vacuum, surrounding the energetic photons.
A force that does not really exist in nature.
If it doesn't exist, why to talk about it and spend money into its study? All scientists, who are claiming, some effect actually doesn't exist (no matter whether it's dark matter, gravity of magnetism) should return their money back.
Vendicar_Decarian
0.2 / 5 (35) Dec 11, 2011
"If it doesn't exist, why to talk about it and spend money into its study" - Callippo

For the same reason that ancient astronomers studied the epicycles of the planets in the earth centered universe.

Since Einstein, Magnetism has been recognized to be a phantom force that is manifest through the method described above.

http://ocw.mit.ed...vity.pdf

http://galileo.ph...mag.html

http://en.wikiped...agnetism

http://arxiv.org/.../0505130
DavidMcC
not rated yet Dec 12, 2011
To be black, it has to absorb light. But since it is so damn tiny, light just misses it. So as afar as the visible and UV spectrum is concerned, the proton simply "isn't there" and not black.


You're still missing the point, that the researchers were not using the word "black" in the literal sense that you are assuming. Rather, they meant that there is a 100% interaction probability within a well-defined area, and 0% outside it. Nothing to do with photons at all!
DavidMcC
not rated yet Dec 12, 2011
... The phrase "looks LIKE a black disc" is the key. It's only an ANALOGY, not to be taken literally.
rawa1
1 / 5 (2) Dec 12, 2011
Since Einstein, Magnetism has been recognized to be a phantom force that is manifest through the method described above.
I don't believe, the magnetism doesn't exist. In particular every force mediates energy and every energy density manifests itself with certain deformation of space-time. In this sense even the magnetic field would be visible around fast rotating charged stars like the gravitational lens. It's simply part of observable reality. If we admit, the magnetic force doesn't exist, than even the electrostatic force or gravitational force doesn't exist. All forces will be just a phantom forces. OK, what next?

The primary criterion of all such claims is: "OK, what it would imply? Which testable predictions we can made with the assumption, magnetic force doesn't exist? If none, why we should bother with it?"

http://imgs.xkcd....eory.png
DavidMcC
5 / 5 (2) Dec 13, 2011
Rawa1, magnetism is a "phantom force" to the extent that Maxwell's equations show it to be entirely due to the relative motion of charges, not the charges themselves (which provide the electric force). That is why this force is properly called "electromagnetic" - it is, in reality, only one force, transformed by inertial frame changes.
BIG COCK
1 / 5 (3) Dec 13, 2011
I read the last word of the article title wrong and almost busted out laughing at work...

DID SOMEONE MENTION BLACK DICK?
tadchem
3.7 / 5 (3) Dec 14, 2011
So the proton does not LOOK like a black disk; one MODEL used to describe the proton is that of a black disk.
DavidMcC
not rated yet Dec 17, 2011
So the proton does not LOOK like a black disk; one MODEL used to describe the proton is that of a black disk.


Yes, but only if you are using the word "black" as an ANALOGY with optical interaction.
Vendicar_Decarian
0.2 / 5 (35) Dec 17, 2011
"It's simply part of observable reality. If we admit, the magnetic force doesn't exist, than even the electrostatic force or gravitational force doesn't exist." - Rawa

If you would take the time to read what has been said, you would see that what you view as a magnetic force is in reality a variance in the electric force as charge particles move relative to an observer.

Magnetic force is strictly electrostatic in origin.

Cin5456
not rated yet Dec 24, 2011
Magnetic force is strictly electrostatic in origin.


Are you saying that a lodestone, the mineral magnetite, does not exist outside of an electical field, or that it exists with an inate charge? I'm not sure that's correct. A magnetic force exists in every caser where there is an electrical charge moving through a conductive material, but not all magnetic force exists only in the presence of a charge.
TychoCraterCafe
not rated yet Dec 26, 2011
So does this support Nassim Haramein's "Schwartzchild Proton" or not?