New details on silicon, subatomic particles and possible ‘fifth force’

https://www.nist.gov/news-events/news/2021/09/groundbreaking-technique-yields-important-new-details-silicon-subatomic

by geox • 5 years ago

318 179 5 years ago

dexwiz• 5 years ago

If this came from almost any other group it would be an easy write off. But NIST really does have some of the best analytical chemists and physicists around.

fennecfoxen2• 5 years ago

Headline is misleading. The "new details" are of the sort "if there is a fifth force, you won't find it over here."

The scientists’ results improve constraints on the strength of a potential fifth force by tenfold over a length scale between 0.02 nanometers (nm, billionths of a meter) and 10 nm, giving fifth-force hunters a narrowed range over which to look.

This is not surprising and it would be possible believe this sort of a thing from a variety of qualified groups.

lilyball• 5 years ago

I’m not sure what’s misleading about it. “If this force exists, you’ll find it in this range” seems to be a valuable detail to know when searching for this force.

It feels to me like this is very similar to the trend of only caring about positive experiment results and thinking negative experiment results aren't interesting. But they are! Negative results are useful and give us information! And are often crucial contributions toward positive results from later experiments.

retbull• 5 years ago

From what I read in this article they didn't prove that the force exists at all they actually showed that it wasn't present in several areas. This helps other people who are doing experiments in the area by cutting down on the range of sizes they need to look in for it but it doesn't provide evidence for its existence.

analog31• 5 years ago

Indeed, and in addition, their research programs focus on improving the science and technology behind making measurements. So they have the best metrologists around too.

wolverine876• 5 years ago

That's impossible. I've learned that only super-wealthy capitalists can accomplish anything.

LeegleechN• 5 years ago

The headline is misleading. The work tightened the range of possible strengths of a fifth force by a factor of 10. In other words it ruled out the existence of a fifth force within a wide range of parameters that were previously open.

kibwen• 5 years ago

Note that the original article's headline is "Groundbreaking Technique Yields Important New Details on Silicon, Subatomic Particles and Possible ‘Fifth Force’" (which is too long for HN), which makes it clear that the focus is on the technique. It's the abbreviated HN title that sort of makes it sound as though the focus is on the force.

criticaltinker• 5 years ago

It seems like the title length constraint on HN is a bit too limiting and often results in these types of clarifying comments.

Couldn’t we expect more accurate and higher quality titles by relaxing the length constraint? I’m sure it’s been discussed before here, but I’m struggling to think of downsides from such a change.

RedShift1• 5 years ago

Is this fifth force something that could disappear with more precise measurements of the known 4 forces?

garmaine• 5 years ago

There is nothing to disappear. There isn’t a fifth force to within experimental precision. TFA is about an increase in that experimental precision which further reduces the possibility (or at least the magnitude) of any yet undiscovered “fifth force.”

Out_of_Characte• 5 years ago

The fifth force is already a hypothetical. More precise measurements would make the hypothetical force weaker and weaker.

vikingerik• 5 years ago

Good point. The details are "constraints on a fifth force if one exists", NOT behavior that indicates it does or might.

whimsicalism3• 5 years ago

If anything, it can be viewed as evidence that this fifth force does not exist - as we can rule out more possibilities.

Raineer• 5 years ago

As a Boulderite and a huge fan of NIST, I am bummed out that the misleading headline does come from NIST itself and not an overzealous contributor.

Exciting results, all the same.

blondin• 5 years ago

wait, how is what they wrote misleading?

prutschman• 5 years ago

It's not literally false, but I got an inaccurate impression based on the headline. To me it implied a positive discovery of evidence rather than a ruling-out.

If they'd said "determined new constraints on a hypothetical 5th force" or something I would have gotten a correct impression.

potatoman222• 5 years ago

I've always wondered why there has to be a discrete number of forces, rather than it being a spectrum describing types of interactions.

macksd• 5 years ago

There may not have to be, as far as we know. From the Wikipedia page[1]:

Many theoretical physicists believe these fundamental forces to be related and to become unified into a single force at very high energies on a minuscule scale, the Planck scale, but particle accelerators cannot produce the enormous energies required to experimentally probe this. Devising a common theoretical framework that would explain the relation between the forces in a single theory is perhaps the greatest goal of today's theoretical physicists. The weak and electromagnetic forces have already been unified with the electroweak theory of Sheldon Glashow, Abdus Salam, and Steven Weinberg for which they received the 1979 Nobel Prize in physics. Some physicists seek to unite the electroweak and strong fields within what is called a Grand Unified Theory (GUT). An even bigger challenge is to find a way to quantize the gravitational field, resulting in a theory of quantum gravity (QG) which would unite gravity in a common theoretical framework with the other three forces. Some theories, notably string theory, seek both QG and GUT within one framework, unifying all four fundamental interactions along with mass generation within a theory of everything (ToE).

[1] https://en.wikipedia.org/wiki/Fundamental_interaction

akamoonknight• 5 years ago

Another related thing I've wondered is if, similar to how the possible electroweak force un-unified into the electromagnetic force and the weak force, is there a scenario where the electromagnetic force (or the weak force) un-unifies into some other sub force ? So I guess like the reverse of the GUT.

at_a_remove2• 5 years ago

Forces are mediated by fields (or particles, depends on your interpretation). If you want 4.5 forces, what does that .5 look like?

Essentially, each force does describe a type of interaction. So what does one-third of a type look like?

klodolph• 5 years ago

We used to think that electricity and magnetism were different types of interaction, but it turns out that they are more coherently described as a single “electromagnetic” force.

The same may be true of other seemingly different forces: https://en.wikipedia.org/wiki/Grand_Unified_Theory

malwarebytess• 5 years ago

Maybe something like fractional dimension in fractals. lol

cybernautique7• 5 years ago

I'm not very knowledgeable of physics, but my intuition is that a fractional type should just be a type that falls between the characteristics of two integer types. So if A is the electromagnetic force and B is the strong nuclear force, A.5 should be some interaction that exhibits characteristics of both, is fully described by neither, yet exhibits no properties which can't be typified by some combination of the integer endpoints.

Of course that raises the question of "shouldn't A.5 then just be considered its own type?" at which point I suppose we'd have to refer to how these "types" are constructed, which seems more like a mathematical/computational (ontological?) question than a purely physics question. Then, I suppose, the question further resolves to: which assumption makes our equations easier to work with?

Please correct me if I'm entirely off-base.

roywiggins4• 5 years ago

The known forces, other than gravity, are mediated by specific particles that have characteristic masses and other properties.

https://en.m.wikipedia.org/wiki/Gauge_boson

(there might be a graviton, too)

With a Grand Unification Theory, they might turn out to be one force with several aspects (eg electroweak force), but that's not really a continuum.

maxerickson2• 5 years ago

Is "particle" the correct model, or is it just very useful?

civilized2• 5 years ago

I've always wondered why there has to be a discrete number of elements, rather than it being a spectrum describing different types of materials.

themodelplumber• 5 years ago

I always wondered, why stick with spectra rather than an ever-expanding set of infinite-dimensional workspaces, mental models, and metaphor...?

cjfd• 5 years ago

I think if there is a spectrum in interactions between the two forces joined by this spectrum would be considered one force. Of course, there is a history of forces that once appeared to be distinct turning out not to be distinct but one and the same force instead. There is a line of thinking that speculates that all four known forces are to be joined in one.

mensetmanusman2• 5 years ago

Good question. Consider the interesting fact that there are discrete energy levels instead of a continuum of energies for an electron in an orbital. This was a profound discovery at the time because it does seem like things should be more analogue than digital :)

potatoman222• 5 years ago

Neat. Can the energy levels described by a probability distribution?

sroussey2• 5 years ago

Actual title:

Groundbreaking Technique Yields Important New Details on Silicon, Subatomic Particles and Possible ‘Fifth Force’

sroussey2• 5 years ago

“A vastly improved understanding of the crystal structure of silicon, the ‘universal’ substrate or foundation material on which everything is built, will be crucial in understanding the nature of components operating near the point at which the accuracy of measurements is limited by quantum effects,” said NIST senior project scientist Michael Huber.

monocasa3• 5 years ago

Each neutron in an atomic nucleus is made up of three elementary particles called quarks.

Well and tons and tons of virtual particles popping in and out of existance. Only a little over 1% the mass of a neutron is the three quarks normally listed.

tomrod• 5 years ago

I love that our fundamental reality is built on virtual particles. Physics rocks!

JackFr• 5 years ago

I love that our mental model of reality is built on virtual particles. Metaphysics rocks!

hongsy• 5 years ago

Only a little over 1% the mass of a neutron is the three quarks normally listed.

Do you have a source for this?

monocasa3• 5 years ago

You can add up the mass of one up quark (2.2MeV) and two down quarks (4.7MeV each) and compare that to the mass of a neutron (939.565MeV)

blobster• 5 years ago

https://www.newscientist.com/article/dn16095-its-confirmed-m...

cwillu2• 5 years ago

https://profmattstrassler.com/articles-and-posts/particle-ph... has a very good explanation.

amerine3• 5 years ago

Are virtual particles a real thing or just a description of the underlying system?

monocasa3• 5 years ago

Just as real as the concepts of particles at all. They're just really likely to recombine because they form in pairs of opposite charges and will attract and annihilate. Hawking radiation is adding another force with a gradient (extremely strong gravity near an event horizon) that'll absorb one of the particles of the pair, and then the other flies off into space as the real, bona fide particle it always was.

Fordec• 5 years ago

Virtual particles are the universes equivalent of local variables inside a function. Parameters go in, results come out, but what stays in that local context still existed even if they didn't have global scope.

tux3• 5 years ago

While they are real, the name is a little misleading. Virtual particles are not quite the same kind of disturbance in a field as full-blown, bona-fide, certified particles.

They're two different kind of object that come out of the equations, and they happily interract or turn into each other sometimes.

But Virtual Particle doesn't mean they're not real, and also doesn't mean they're particles :)

Disclaimer: I'm ignorant, and this is my summary of Matt Strassler off the top of my head. Mistakes are mine.

Source: https://profmattstrassler.com/2011/10/10/virtual-particles-n...

kamaal• 5 years ago

>Only a little over 1% the mass of a neutron is the three quarks normally listed.

Pardon my layman ignorance. When the particles pop in and out of existence, how does mass manage to remain the same? Or does mass keep changing and is not fixed quantity but rather a range?

And what do come out of, and where do they go?

scotty797• 5 years ago

The mass of the 99% comes from (kinetic?) energy that quarks have as the come together to from a neutron. This system has some energy like a rope moved by standing wave. Standing wave is a sum of waves traveling back and forth and sometimes adding up and sometimes cancelling each other into nothing.

Gluons pop up out of nothing to carry this energy that struggling bound quarks have and add up into nothing passing their energy back to quarks.

If you pump in even more energy into this system (for example by smashing something into it) even something like new quark-antiquark pair can pop up into existence and one of the original quarks might fly off away with one of the new particles to form a separate meson. The other particle from the created pair stays and changes the identity of three quark particle so it's no longer a neutron but some other three quark particle.

scotty797• 5 years ago

But the quarks give it it's identity. That's why they say it's made up from them, I assume.

rossjudson• 5 years ago

It's love, right? I saw the movie.

tiborsaas• 5 years ago

It's a confusing force. When two particles interact via love they possess this fore which always equate to 1LUV. Tragedy is that it's unstable and one always has more than the other, 50:50 split is rarely seen. It's even possible that during an interaction one can have all the love and the other none and they still bind together in a way.

loloquwowndueo• 5 years ago

Fifth force? So … water, fire, earth, air and what else??? :)

aemreunal• 5 years ago

...and love.

Cats_In_Love2• 5 years ago

Nice.

KyleBrandt• 5 years ago

Pardon the comment noise, but I can't help but highlight that "Fifth Force of Nature" is an excellent name for a band.

niccl• 5 years ago

Quintessence. That's what it means:

  '(In Ancient and Medieval philosophy) ether, the fifth and highest essence or element after earth air, water and fire, which was thought to be the constituent matter of the heavenly bodies and latent in all things. [C15 via French from Medieval Latin 'quinta essentia' the fifth essence]

From Collins English Dictionary

kordlessagain5• 5 years ago

Aether

scotty797• 5 years ago

stupidity

I always treated stupidity as a fifth element that can bring great and surprising tragedies to humanity.

Cats_In_Love2• 5 years ago

I understand the interest in a fifth force is to explain the dark matter/dark energy anomaly discovered by the astronomer Vera Rubin. The orbital velocities of stars at increasing radii (radiuses?) from the center can't be accounted for by the current understanding of gravity and visible matter.

kazinator2• 5 years ago

Pardon my following likely idiotic statement from a layperson, but the surprising matter of the charge distribution within the neutron suggests that the nuclear "weak force" is actually just electrostatic force. So that is to say, if the neutron is slightly negative near the surface, what if that's the entire basis of the force that makes neutrons able to bind protons in the atom nucleus. We would expect this to be a kind of dipole whose field drops off rapidly with distance.

LegitShady• 5 years ago

https://en.wikipedia.org/wiki/Electroweak_interaction

thayne2• 5 years ago

First of all, the nucleus is held together by the strong nuclear force, not the weak nuclear force (the weak force causes certain kinds of decay, such as a neutron to decay into a proton and electron).

Secondly, as soon as you have multiple protons, the repulsion from the positive charges will be much, much greater than any dipole attraction.

Finally, physicists have done a lot of really precise measurements with subatomic particles, and I don't think a dipole interaction like that would match the observed results.

kazinator2• 5 years ago

Right! The strong nuclear force is over two orders of magnitude stronger than electromagnetism, so it cannot be caused by it.

It has to be, in order overcome the vehement repulsion among the protons.

betterunix24• 5 years ago

Actually the relationship between the weak nuclear force and the electromagnetic force is well understood. It would have to be related, given that the weak interaction is the cause of beta decay, which results in a neutron becoming a proton (which has a positive electromagnetic charge) and the creation of an electron (which has a negative charge). The force carrying particles of the weak force can also have electromagnetic charge, further demonstrating the connection between the two phenomena.

You can reason about all the forces being related in some way. For example, beta decay happens in free neutrons, but does not happen in a helium-4 nucleus; there should be a connection with the strong nuclear force that explains this. In some sense the fact that we can observe or measure an interaction implies that it must be related to other forces, since our ability to make an observation is itself dependent on such connections (in the end you need some electromagnetic effect that your eyes can perceive).

Yaggo• 5 years ago

In school, 25 years ago, I was taught the "circling balls" atomic model and for me physics seemed kind of boring and very stable field of science, like we already knew almost everything.

Nowadays, thanks to superb youtube channels[1], I've learnt that we are rather in the beginning of the journey of solving the mystery of universum, and the reality is much more exciting than those boring "circling balls"; actually there are no balls at all but just "fields" (which of course is also just a mental model).

[1] E.g. https://www.youtube.com/user/TheScienceAsylum

hutzlibu2• 5 years ago

To me it seemed as well, that my physics teachers mindset was unchanged and frozen to the classical deterministic physic mindset of prequantum discoveries. It was actually believed in 18xx), that theoretical physics was allmost solved.

But somehow this very wrong idea prevailed and made it to my school as well.

codeulike• 5 years ago

It's deliberate, you get taught different models of the atom etc the deeper you get into physics/chemistry. In that way you also learn about models and the scientific method and how the advances have been made.

In the same way that Newtonian physics is still useful for a lot of stuff, the circling balls model of the atom can still be useful in some areas

chii2• 5 years ago

a good way to teach these physics to students is to lead them through the ages by teaching the old models, then let them find out in experiments those models' incorrectness, and then teach them the new discovered models that more correctly predicts reality, and continue.

You can do this with the atom, you can do with with Newtonian physics (and teach relativity as a result). You can do with classical physics of matter, then teach the double slit experiments, and then teach quantum mechanics as follow ups etc .

naasking• 5 years ago

classical deterministic physic mindset of prequantum discoveries

This model can extend into the quantum realm as well if approached correctly, like with Bohmian mechanics.

slightwinder• 5 years ago

In school, 25 years ago, I was taught the "circling balls" atomic model and for me physics seemed kind of boring and very stable field of science, like we already knew almost everything.

School-level of physics is pretty stable. There wasn't anything radical new in decades. Most things pupils learn is around 100-300 years old, because everything else is too complicated for them and mostly unnecessary. Even physics I learned at university took several years till it reached more modern levels.

scotty797• 5 years ago

I hate the circling ball model because it gives so many people completely wrong intuitions about what is actually happening in the world of particles.

After that kind of education people tend to imagine particles as little balls traveling through space and bouncing and occasionally doing something magical that normal balls don't do (like not having a radius or interacting with itself).

While what actually happens (according to better models) is that paricle is a nebulous object that evolves moving and reshaping and when we interact with it with it our measurement devices we reshape it and get results as if there was at given point in time some mass with some charge and spin and whatever at some region of space with some momentum and energy limited to some range. And to guess what will be similarily vague result of the next interaction with that object we in many cases can't draw a line and say "the ball flew throug there". And the lines we draw when we can, represent the motion of the whole fuzzy cloud that actually is the particle as it evolves in space.

I think we should start teaching model of the atom starting from the orbitals and treat classical model of the atom only slightly better than "raisin model" of the atom because what it gets right it gets right only because wave function evolution equations in some very specific cases simplify to classical equations of motion and we learned them first by observing macroscopic objets that are that special cases of motion.

The image of p orbital should suffice to explain to people why the circular model is wrong.

phreeza2• 5 years ago

The circling ball/shell model is extremely useful and intuitive for high school chemistry though, so changing one without the other probably will cause more harm than good. I am a physicist and to be perfectly honest when I have to understand some kind of chemistry, my mind still uses the shell model.

edumucelli• 5 years ago

It makes me wonder that infinite things are still "hidden" from our understanding. As the silicon is widely used on our modern society we have spent enough time studying its properties. What about other materials, there is potentially an "universe" on everything and that is incredible.

pharke• 5 years ago

“Generally, if there’s a force carrier, the length scale over which it acts is inversely proportional to its mass,”

How does this apply to gravity, if at all?

svenpeter• 5 years ago

It’s been a while since my last physics lectures so this might be wrong, but the way i understand it:

We don’t have a good model of quantum gravity yet but our best guess is that the force carrier of gravity might be a particle called graviton. This hypothetical particle has no mass and therefore the length scale of gravity would be infinite. This matches the Newtonian and the general relativity model of gravity.

This is different from the source of gravity which would be the (gravitational) mass of an object (or more accurately the components of the stress energy tensor which describe the density and flux of energy but that’s also the point where I have to start with the hand waving because my knowledge becomes very fuzzy there)

It’s also true for the electromagnetic interaction: the force carrier here is the photon which is also massless and the length scale is also infinite here.

betterunix24• 5 years ago

That is the big question in physics today! There is the hypothetical "graviton" which, as you should expect, has zero mass. There are theoretical problems due to the poorly understood interaction of general relativity and quantum mechanics -- if you could resolve those problems you would have a "theory of everything."

kordlessagain5• 5 years ago

See http://ayuba.fr/mach_effect/estes_park/ssi_estes_park_procee...

New details on silicon, subatomic particles and possible ‘fifth force’

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