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They show the forces tangential to the surface of the proton, going around one way near the "surface" and the other way in the middle. However, the hairy ball theorem says there must be something like "poles" in this case.
https://en.wikipedia.org/wiki/Hairy_ball_theorem
I'm wondering if their proton map covers that, and if the "axis" corresponds to anything familiar.
The image halfway through the article says the forces are "twisting shear forces," which "twist one way [or] the other"—only two ways to twist!
Maybe by "twisting" the author means that the field is one of torques rather than of linear forces. I guess you can make a continuous field of torques tangent to the surface of a sphere (as long as you're speaking of the "wheel" of the torque, not its pseudovector axis, being tangent to the sphere).
In addition, you can only speak of two "ways" any particular torque in such a field can go: clockwise or counterclockwise, as viewed from, say, a point inside the sphere. That would explain the one-way-or-the-other language.
Below quote from your wiki link. I’m not a graphics guy, but would appreciate if someone with experience in computer graphics could please give an example of this common problem.
“A common problem in computer graphics is to generate a non-zero vector in R3 that is orthogonal to a given non-zero vector. There is no single continuous function that can do this for all non-zero vector inputs.”
Humans have an intuitive understanding of "up", so there's usually a single obvious way to orient a camera when taking photos. However, what happens when you point a camera straight up or down? There's no longer an obvious choice, any direction you choose is reasonable (orthogonal)!
Another way to think about it is assigning cardinal directions to the Earth. Which way is north from the north pole? There's no possible way to create a map that has defined directions at every point.
The pictures in the Wikipedia article give a great intuitive understanding, particularly if you can figure out why a sphere and torus behave differently. (You can build a globally consistent map on a torus.)
> There is no single continuous function that can do this
Nitpick: that should be "no single continuous deterministic function"; it's (relatively) very easy to sample uniformly randomly from the unit circle orthogonal to a given non-zero vector, but that won't give, for example, approximately the same result on two consecutive video frames, such that you could usefully orient the camera with that direction "up".
Is this a consequence of tan(90) being undetermined? (approaches +infinity from one side and -infinity from the other)
i might be misunderstanding , but it seems easy
if you want a vector orthogonal to A , generate a random vector B non co-linear to A and take AxB (cross product). AxB is orthogonal to A .
What example of what common problem? That's a true statement, and its proof is right above it, in the wiki page?
It's not very clear and this is not my area, but I think it's relevant that the proton has spin != 0. [1]
<guess> I think that the graphic assumes that the spin on the proton is pointing up (perpendicular to the sheet of paper) and the forces that are drawn are parallel to the "equator". In the "north pole"and "south pole" there are no forces.</guess>
[1] The spin is 1/2, but I guess the exact value is not important for this, only that it's not null.
If I understand their diagram correctly I would guess that it is somewhat nuanced. Those shear forces are probably related to the internal angular momentum of the proton. But in quantum mechanics you cannot precisely measure the axis of a particle's angular momentum. You can only measure the total magnitude and the component along one axis. Because of this there wouldn't be any regions you can point to that are "poles" where there is no angular momentum.
It's not applicable. The theorem applies to the boundary of 1+2n dimensional balls - surface of an ordinary sphere, bulk of a 5-ball, 6-surface of a 7-ball, etc.
The Toroidal Physical Model
How can it make sense to measure the stress-energy tensor of a proton given that we have no theory of quantum gravity? Are they somehow ignoring quantum mechanics?
This is preliminary work. The bigger issue is that this is happening at energy scales that ignore things like gluons.
> Sharper gravitational maps of both the proton’s quarks and its gluons may come in the 2030s when the Electron-Ion Collider, an experiment currently under construction at Brookhaven, will begin operations.
It would be hard to imagine the scientists are ignoring quantum effects since light + proton screams quantum, so it's unclear from the reporting alone if the lack of a quantum gravity theory is enough to make all this not particularly useful or if this is just bad reporting and the experts are confident this is the right way to do things "for reasons". My guess it's probably a mixture because the modelled answer computed from equations and the measured result seem to be aligned.
They are measuring the distribution of energy within the proton. General relativity (GR) describes how a distribution of energy distorts spacetime. They could take these measurements of the proton (if they're complete enough) and compute its tiny effect on the curvature of spacetime with non-quantum GR. Quantum gravity only becomes relevant at the Plank length (~10^-35m) which is still much smaller than the proton radius (~10^-15m) or the resolution of their measurements.
The methods scientists come up with to test things like this are absolutely incredible, wow.
I remember being blown away when I was told about Henry Cavendish’s attempt to calculate G (the gravitational constant) in the late 18th century: https://en.wikipedia.org/wiki/Cavendish_experiment
"Attempt" may be an understatement, as it worked.
We hat this experiment set up in one of our lecture halls once a year. They had to fence off the area and it had to relax for days, but we were able to replicate the measurement during our introduction to physics lecture.
There was also a lab course on a smaller version. (Video of it, in German though: https://m.youtube.com/watch?v=8W8X71wW8F0)
Same guy who discovered, among other things,
> the concept of electric potential (which he called the "degree of electrification"), an early unit of capacitance (that of a sphere one inch in diameter), the formula for the capacitance of a plate capacitor, the concept of the dielectric constant of a material, the relationship between electric potential and current (now called Ohm's law) (1781), laws for the division of current in parallel circuits (now attributed to Charles Wheatstone), and the inverse square law of variation of electric force with distance, now called Coulomb's law.
(Wikipedia)
Wonder what went wrong to need so many rediscoveries by others. Reminds me of Gauss.
It's kind of like creatively debugging the universe, constructing weird scenarios to explore the edges of things to fill in missing terms in a model.
Continuing on this path of scientific enquiry, will we at some point finally understand what this is all about? Why there should be such a thing as a proton, and why it has the properties it does?
Some things just “are”. There is no “why”. There is a “how”, and we may never be able to answer that question.
Science doesn’t really answer “why”. It’s better at “how”.
Had there been any scientific studies into why the elements are perfect and there are are all apparent to perfect replicas with not defect rates? It’s hard to make perfect replicas at scales higher than the atomic scale but at the lowest levels, everything seems to be identical.
I find Alan Watts to be informative in pondering these kind of questions, as "why" isn't really in the realm of science.
I think, in fact, that there might be more than one proton.
Probably we will at some point. It is possible that it will turn out that our whole world is, say an ever growing finite system with a simple rule. Say someone identifies some laws ruling the digits of pi, that's a physics, then they look more, and they observe that the CMWB pattern on the sky is in the pi too, and voila, we live in pi confirmed (or at least it would make it very plausible). Then protons exist, and protons are the way they are, because some properties of the circle.
If you feel like this article is pretty empty in terms of "answers" and "new directions" and the fact that research group has been pushing these ideas for years, again, without any breakthroughs or challenging present understanding, what do you think that means for the quality of the research? This is at best a "ok, neat" result with some science journalism overreaching of how relevant it is for gravity.
Is there a relationship between the intense forces here that are apparently balanced and stable and the fact that mass is equivalent to insane amounts of energy (via E=mc^2)?
Is mass basically a ball of balanced forces ready to explode if this balance is disrupted?
If so then it seems interesting that this tension's potential energy maps exactly to mc^2.
I think what you're describing is called the stress-energy tensor, which as I understand it is a generalization of mass.
Since matter is basically precipitated energy from the near infinite energies released by the Big Bang, makes sense to me that it has fairly high amounts of energy compacted.
If nothing else, nuclear bombs made this blindingly obvious.
It is true in general that the "binding energy" of a nucleus is reflected in the measured mass or atomic weight, exactly as mc^2.
I always wonder, how exactly are gravitons or gluons supposed to create the attraction between two particles? They carry a negative momentum or its just magic? Does it mean that the gravitational force is fluctuating with some statistical distribution of gravitons?
Thinking of a virtual graviton or photon or gluon as a particle is somewhat misleading. It is better to think of it as an excitation of the underlying field.
It is possible to show (with fairly elementary techniques) that when the excitations have a spin of 2, these excitations always reduce the energy of the system, and so produce an attractive force. If the excitations have a spin of 1, then they increase the energy of the system and so produce a repulsive force. This is why the gravitational force attracts and like charges repel each other.
They’re virtual particles, and can get away with having negative energy. They don’t always obey mass energy equivalence either, naughty things.
> .. a graviton, the hypothesized particle that conveys the force of gravity
I thought it was the Higgs boson that was doing this? But obviously I misunderstood something. Could anybody explain what's the difference between those particles?
Higgs boson conveys mass. Mass is not necessary for a gravity field. Massless particles such as photons can convey both gravity fields and momentum.
In short, gravity is correlated with energy density, which coincides with mass (via e=mc2) but the mass itself is not directly responsible for the gravity field, per se.
The Higgs boson (or maybe the Higgs field?) gives mass to everything else. The graviton creates the attractions between masses.
I believe the Higgs boson is what generally gives particles mass, which is different from particles which create fields and forces?
> They found that in the heart of the proton, the strong force generates pressures of unimaginable intensity — 100 billion trillion trillion pascals, or about 10 times the pressure at the heart of a neutron star. Farther out from the center, the pressure falls and eventually turns inward, as it must for the proton not to blow itself apart.
This is inside each of us, 100 billion billion billion times
As humanity continues to peel back the layers of reality, I sure feel more and more like maybe this indeed is a simulation.
Here, see this and relax:
On the bright side, finding out that we are all in a simulation would at least provide the answer to the perennial question about the meaning of life, dohohoho.
I'm "positive" this will be a great read.
I'm glued-on to my computer screen!
> “It’s a tour de force,” said Cédric Lorcé
I see what he did there.