LHC restart

[Gfamily]

As has been reported this morning, the LHC is being restarted after its recent cycle of upgrades.

If people are interested, there's a dashboard showing the status of various components that looks pretty.

http://meltronx.com/index.html

Click on individual panels to view them full screen like this (NB - this one is real-time, so may become very boring at times)

[Cardinal Fang]

So CTRL-ALT-DEL won't suffice?

[shpalman]

So how long before it's confirmed that there's no supersymmetry in this energy range either? I reckon there'll be two or three tentative announcements of "new particles" which will evaporate before they reach a decent sigma though.

[Gfamily]

Proper science
http://meltronx.com/index.html

[nekomatic]

Good to see none of those 7.5 billion euros was wasted on UX design.

[Gfamily]

Good to see none of those 7.5 billion euros was wasted on UX design.

I guess it depends on who the U's are, and what they need.

[shpalman]

It was great when we found the Higgs wasn't it? Remember that?

“More data and a little bit more energy opens new opportunities,” said Bortoletto. She said scientists would be able to study the Higgs boson in more detail, and the work may also provide new insights into the mass of the W boson. Another fundamental particle, the W boson was at the heart of a sensation earlier this year when researchers at the Collider Detector at Fermilab in the US revealed their data suggested the particle has a far very slightly greater mass than predicted by the standard model.*

Well at least it's not "LHC collisions might produce dark-matter particles... The collider might also shed light on the more predominant “dark energy,”... the LHC may reveal extra dimensions of space... if these extra dimensions are configured in certain ways, the LHC could produce microscopic black holes... Supersymmetry could be discovered by the LHC..."

* - http://backreaction.blogspot.com/2022/0 ... model.html

science.abk1781-f1.jpg (70.68 KiB) Viewed 2010 times

[shpalman]

“If they don’t find anything, this field is dead”

The standard model describes everything scientists have seen at particle colliders so far. Yet it cannot be the ultimate theory of nature. It leaves out the force of gravity, and it doesn’t include mysterious, invisible dark matter, which appears to outweigh ordinary matter in the universe six to one.

The LHC was supposed to break that impasse... A decade ago many physicists envisioned quickly spotting marvels including new force-carrying particles or even mini–black holes. “One would drown in supersymmetric particles,” recalls Beate Heinemann, director of particle physics at the German laboratory DESY. Finding the Higgs would take longer, physicists predicted.

Instead, the Higgs appeared in a relatively speedy 3 years—in part because it is somewhat less massive than many physicists expected, about 133 times as heavy as a proton, which made it easier to produce. And 10 years after that monumental discovery, no other new particle has emerged. That dearth has undermined two of physicists’ cherished ideas. A notion called naturalness suggested the low mass of the Higgs more or less guaranteed the existence of new particles within the LHC’s grasp.

Spoiler: they weren't there, because "naturalness" is an aesthetic principle not a scientific theory.

All we have are

... small discrepancies between observations and standard model predictions—that physicists will explore in the LHC’s next 3-year run. For example, in 2017, physicists working with LHCb, one of four large particle detectors fed by the LHC, found that B mesons, particles that contain a heavy bottom quark, decay more often to an electron and a positron than to a particle called a muon and an antimuon. The standard model says the two rates should be the same, and the difference might be explained by the existence of exotic particles called leptoquarks, which could already be hiding undetected in the LHC’s output, Ellis says.

Similarly, experiments elsewhere suggest the muon might be very slightly more magnetic than the standard model predicts (Science, 9 April 2021, p. 113). That anomaly could be a hint of supersymmetric particles or leptoquarks, Ellis says.

or

... in August 2020, teams of physicists working with the LHC’s two biggest detectors, ATLAS and CMS, announced that both had spotted the Higgs decaying to a muon and an antimuon. If the rate of that hard-to-see decay varies from predictions, the deviation could point to new particles hiding in the vacuum, says Marcela Carena, a theorist at Fermi National Accelerator Laboratory.

[IvanV]

“If they don’t find anything, this field is dead”

I think this rather pithily expresses the issue that has been apparent for a long while.

Others are less sanguine about LHC experimenters’ chances. “They’re facing the desert and they don’t know how wide it is,” says Marvin Marshak...

I was rather intrigued the other day by someone looking at those "small discrepancies" currently under investigation, and asking a question I'd never thought about, because I'd never realised it was a question. And that is the quantum of charge for leptons vs the quantum of charge for baryons. Very convenient that they are precisely the same. Without it, atomic matter would be in crisis. But our present theories give so little relationship between leptons and baryons, that there seems to be no reason why they should come in the same quantum of charge. It is one of those things that just is, but lacks even the start of an explanation. And that was leading in to how convenient it would be if leptoquarks existed, and the various leptoquark hints in those hints of discrepancies. But, of course, there are many convenient things that could fix the longstanding holes in our theories, and they stubbornly refuse to appear.

[shpalman]

“If they don’t find anything, this field is dead”

I think this rather pithily expresses the issue that has been apparent for a long while.

Others are less sanguine about LHC experimenters’ chances. “They’re facing the desert and they don’t know how wide it is,” says Marvin Marshak...

I was rather intrigued the other day by someone looking at those "small discrepancies" currently under investigation, and asking a question I'd never thought about, because I'd never realised it was a question. And that is the quantum of charge for leptons vs the quantum of charge for baryons. Very convenient that they are precisely the same. Without it, atomic matter would be in crisis. But our present theories give so little relationship between leptons and baryons, that there seems to be no reason why they should come in the same quantum of charge. It is one of those things that just is, but lacks even the start of an explanation. And that was leading in to how convenient it would be if leptoquarks existed, and the various leptoquark hints in those hints of discrepancies. But, of course, there are many convenient things that could fix the longstanding holes in our theories, and they stubbornly refuse to appear.

It's especially interesting since baryons are made of quarks which have charges of either a third or two thirds the elementary charge (plus or minus depending on which quarks or antiquarks they are) so that they can add up to exactly zero or exactly one elementary charge, or whatever. Well, quarks behave as though they have these third-of-an-integer charges, you can't isolate them.

But there are two points of view. One would be to say there's no such thing as a coincidence so quarks and leptons must both originate from some deeper kind of particle. The other is to be anthropic about it, and point out that nothing so complicated as humans would have evolved in a universe in which atoms can't even exist, so obviously they do.

[IvanV]

But there are two points of view. One would be to say there's no such thing as a coincidence so quarks and leptons must both originate from some deeper kind of particle. The other is to be anthropic about it, and point out that nothing so complicated as humans would have evolved in a universe in which atoms can't even exist, so obviously they do.

Anthropic arguments are just religion more cleverly concealed.

When we sent out probes to explore the solar system, when we pointed the Hubble telescope around the universe, we kept on being amazed at all the kinds of complexity that exist just with our known laws of physics, that we didn't predict. It really is very difficult to say what will exist when you take some simple laws of physics and that's all you know, without any phenomena to observe and explain. So we really have absolutely no idea what kinds of phenomena of extraordinary complexity might exist with different laws of physics, or different physical constants within the same basic laws, or simply even a different course of events such as different collisions between large bodies in the formation of our solar system. It would probably be so different from our own experience we couldn't even imagine it.

The thing about coincidences, in general, is that there are so many other coincidences that didn't happen, it isn't surprising that lots of bizarre coincidences happen. The chance of winning the lottery is exceedingly small, but inevitably someone wins the lottery from time to time. But that's a different kind of coincidence from the charge of a lepton being exactly the same as the charge of a baryon. It isn't that they are nearly the same, like the visible size of the moon and the sun in the sky being nearly the same. It isn't like a lottery pick where 1 time in 14,000,000 the balls show the same number as the ticket you bought. They are exactly the same. There is something there that we don't understand.

[dyqik]

But there are two points of view. One would be to say there's no such thing as a coincidence so quarks and leptons must both originate from some deeper kind of particle. The other is to be anthropic about it, and point out that nothing so complicated as humans would have evolved in a universe in which atoms can't even exist, so obviously they do.

Anthropic arguments are just religion more cleverly concealed.

Anthropic arguments are just pointing out that for us to observe the universe, the universe must be capable of supporting life that can observe the universe.

For complex life capable of forming the concept of "universe" to evolve, there has to be stable local structures capable of evolving in time, i.e. that can store and process information. (There also has to be a concept of time for that processing to occur in, which implies conservation of energy). This requires that particles exist in a form that can be gathered into stable assemblies and configurations, i.e. that are not forced apart rapidly by electromagnetic charges.

People explore variations on our physical laws all the time. Most variations do not allow stable matter or other structures to form, and thus cannot store information.

[IvanV]

Anthropic arguments are just religion more cleverly concealed.

This statement is utterly wrong.

Anthropic arguments are just pointing out that for us to observe the universe, the universe must be capable of supporting life of the type that can observe the universe.

Let me be more precise what I meant. There is a variety of anthropic arguments. My sense is that they are either religion, or else vacuous. The "stronger" claims are religion, the "weaker" ones are vacuous. Vacuous in the sense of not actually taking us anywhere.

You seem to be suggesting that this particular (weak) formulation of the anthropic argument falls into a gap between religion and vacuity. It is formulated as an evident principle (which is what all anthropic arguments try to achieve, so as to conceal their religion, if they have any), and thus not religion. You have clearly chosen this to be weak, but have you avoided vacuousness?

I have two problems with this, and I would suggest either of them is sufficient to make it vacuous.

First, the term "observe" is not well defined. We do not reliably know how to recognise "observation". At least in a philosophical sense. That is related to our philosophical agonising over issues like consciousness and free will. But maybe you have in mind some particular physical notion of observation. For example, maybe some quantum mechanical wave function reduction type of thing - Schrodinger's Cat is only dead if it is observed to be dead. But I do not think that we have really got to the bottom of that. So I am not convinced that "observation" is a restriction.

Second, even if you can make precise what "observation" is, we have absolutely no idea what potential "observers" might exist in alternative courses of events for our own universe, let alone what might exist in alternatives with different laws of physics, or even what is the range of "alternatives" it is valid to consider.

So that's why it seems to me that this weak anthropic statement is probably vacuous.

[dyqik]

Anthropic arguments are just religion more cleverly concealed.

This statement is utterly wrong.

Anthropic arguments are just pointing out that for us to observe the universe, the universe must be capable of supporting life of the type that can observe the universe.

First, the term "observe" is not well defined. We do not reliably know how to recognise "observation". At least in a philosophical sense. That is related to our philosophical agonising over issues like consciousness and free will. But maybe you have in mind some particular physical notion of observation. For example, maybe some quantum mechanical wave function reduction type of thing - Schrodinger's Cat is only dead if it is observed to be dead. But I do not think that we have really got to the bottom of that. So I am not convinced that "observation" is a restriction.

Second, even if you can make precise what "observation" is, we have absolutely no idea what potential "observers" might exist in alternative courses of events for our own universe, let alone what might exist in alternatives with different laws of physics, or even what is the range of "alternatives" it is valid to consider.

You've snipped out the substantive part of my post which addresses this.

As such, I think your argument is vacuous.

[dyqik]

Oh, and the Schrodinger's cat argument is a red herring here. Quantum information theory still places the same requirements on the ability to form stable structures for supporting information, and the (lack of definition of) "observation" in quantum mechanics isn't the same kind of concept as the observation required in formulating the anthropic principle.

[shpalman]

Why the universe is just so
Craig J. Hogan
Rev. Mod. Phys. 72, 1149 – Published 1 October 2000

https://doi.org/10.1103/RevModPhys.72.1149

Some properties of the world are fixed by physics derived from mathematical symmetries, while others are selected from an ensemble of possibilities. Several successes and failures of “anthropic” reasoning in this context are reviewed in light of recent developments in astrobiology, cosmology, and unification physics. Specific issues raised include our space-time location (including the reason for the present age of the universe), the time scale of biological evolution, the tuning of global cosmological parameters, and the origin of the Large Numbers of astrophysics and the parameters of the standard model. Out of the 20 parameters of the standard model, the basic behavior and structures of the world (nucleons, nuclei, atoms, molecules, planets, stars, galaxies) depend mainly on five of them: m_e, m_u, m_d, α, and α_G (where
m_proton and α_QCD are taken as defined quantities). Three of these appear to be independent in the context of Grand Unified Theories (that is, not fixed by any known symmetry) and at the same time have values within a very narrow window which provides for stable nucleons and nuclei and abundant carbon. The conjecture is made that the two light quark masses and one coupling constant are ultimately determined even in the “final theory” by a choice from a large or continuous ensemble, and the prediction is offered that the correct unification scheme will not allow calculation of (m_d − m_u)/m_proton from first principles alone.

[dyqik]

The anthropic principle can only be formulated in, and applied to, a conceptual framework where there are observers and observations, anyway.

The same is true of "laws of physics", which are statements about observations, and require coarse-graining of experience into entities with observed behaviors that can be abstracted into generalized rules.

[IvanV]

This statement is utterly wrong.

Anthropic arguments are just pointing out that for us to observe the universe, the universe must be capable of supporting life of the type that can observe the universe.

First, the term "observe" is not well defined. We do not reliably know how to recognise "observation". At least in a philosophical sense. That is related to our philosophical agonising over issues like consciousness and free will. But maybe you have in mind some particular physical notion of observation. For example, maybe some quantum mechanical wave function reduction type of thing - Schrodinger's Cat is only dead if it is observed to be dead. But I do not think that we have really got to the bottom of that. So I am not convinced that "observation" is a restriction.

Second, even if you can make precise what "observation" is, we have absolutely no idea what potential "observers" might exist in alternative courses of events for our own universe, let alone what might exist in alternatives with different laws of physics, or even what is the range of "alternatives" it is valid to consider.

You've snipped out the substantive part of my post which addresses this.

I thought I was addressing it. Let me point out more specifically how my two objections relate to what you wrote. As I said, I think either of my two objections suffice, but I mention both.

For complex life capable of forming the concept of "universe" to evolve,

This phrase relates to my first objection. I think it is the only place where you address it.

Your anthropic concept was based on "observe". You are assuming here, it would appear, that "observe" require complex life. I do not think that is clear. We need a precise definition of "observe" for these purposes, and I do not think we have one. It is far from clear to me that complex life is needed. Suppose earth has the only complex life in the universe. What does that mean for the first 10bn years of our universe? The earth was far from inevitable, as far as we can tell.

...there has to be stable local structures capable of evolving in time, i.e. that can store and process information. (There also has to be a concept of time for that processing to occur in, which implies conservation of energy). This requires that particles exist in a form that can be gathered into stable assemblies and configurations, i.e. that are not forced apart rapidly by electromagnetic charges.

Now we move to my second objection. I would suggest that these arguments are based on assumption that the only kinds of stable structures are analogous to the kinds of things we already know about, the kinds of particles and atoms we know about. The last sentence appears to reveal that assumption. As I mentioned previously, as we explored the solar system and the universe, we kept on finding stuff we never anticipated. And that's with the laws of physics we are familiar with. So I really don't have much confidence in the ability of physics to predict stuff beyond sufficiently close analogy with their known experience.

People explore variations on our physical laws all the time. Most variations do not allow stable matter or other structures to form, and thus cannot store information.

So we make a small adjustment to the known laws or constants and known matter falls apart. There could be totally different kinds of stable, information-storing structures with different laws of physics, things beyond analogy with what we know about in our present universe, arrangements we wouldn't even call matter. You do try and predict my objection by saying "other structures". I don't think we know how to reliably exclude such possibilities far beyond our present imaginings. And this is only my second objection of the two.

Anthropic arguments are also used not only in relation to alternative laws of physics, they are also used in relation to alternative courses of events within our present laws of physics. For example, had the moon been a rather different size, it would have had a major effect on the potential for evolution of life as we know it on the earth. Even within our present laws of physics, we really have very little idea whether complex life is common in our universe, or unique to Earth. Whether our chemistry is the only kind of complex life, or if there could be quite different complex life that could evolve with a rather different chemistry in different conditions. Such is our very limited ability to work out what possibilities might exist within a set of laws of physics, that we have great difficulty doing it even with the laws of physics we know, where we have some data to go on. As for alternative laws of physics where we have no data to go on, well you'd have to be remarkably confident with our ability to understand the full range of their potential implications to say that you can really exclude everything. We really don't understand well enough how physics works to do that.

[shpalman]

First, the term "observe" is not well defined. We do not reliably know how to recognise "observation". At least in a philosophical sense. That is related to our philosophical agonising over issues like consciousness and free will. But maybe you have in mind some particular physical notion of observation. For example, maybe some quantum mechanical wave function reduction type of thing - Schrodinger's Cat is only dead if it is observed to be dead. But I do not think that we have really got to the bottom of that. So I am not convinced that "observation" is a restriction.

Second, even if you can make precise what "observation" is, we have absolutely no idea what potential "observers" might exist in alternative courses of events for our own universe, let alone what might exist in alternatives with different laws of physics, or even what is the range of "alternatives" it is valid to consider.

You've snipped out the substantive part of my post which addresses this.

I thought I was addressing it. Let me point out more specifically how my two objections relate to what you wrote. As I said, I think either of my two objections suffice, but I mention both.

For complex life capable of forming the concept of "universe" to evolve,

This phrase relates to my first objection. I think it is the only place where you address it.

Your anthropic concept was based on "observe". You are assuming here, it would appear, that "observe" require complex life. I do not think that is clear. We need a precise definition of "observe" for these purposes, and I do not think we have one. It is far from clear to me that complex life is needed. Suppose earth has the only complex life in the universe. What does that mean for the first 10bn years of our universe?

As far as we know, there weren't any theoretical physicists during that time. This isn't about quantum mechanical observation, this is about there being something complicated enough in the universe to be able to contemplate the nature of the universe.

[shpalman]

...there has to be stable local structures capable of evolving in time, i.e. that can store and process information. (There also has to be a concept of time for that processing to occur in, which implies conservation of energy). This requires that particles exist in a form that can be gathered into stable assemblies and configurations, i.e. that are not forced apart rapidly by electromagnetic charges.

Now we move to my second objection. I would suggest that these arguments are based on assumption that the only kinds of stable structures are analogous to the kinds of things we already know about, the kinds of particles and atoms we know about. The last sentence appears to reveal that assumption. As I mentioned previously, as we explored the solar system and the universe, we kept on finding stuff we never anticipated. And that's with the laws of physics we are familiar with. So I really don't have much confidence in the ability of physics to predict stuff beyond sufficiently close analogy with their known experience.

Particle physicists predict all sorts of extra families of particles, which we then fail to find at CERN.

[shpalman]

So we make a small adjustment to the known laws or constants and known matter falls apart. There could be totally different kinds of stable, information-storing structures with different laws of physics, things beyond analogy with what we know about in our present universe, arrangements we wouldn't even call matter. You do try and predict my objection by saying "other structures". I don't think we know how to reliably exclude such possibilities far beyond our present imaginings. And this is only my second objection of the two.

There could be, but in this universe there isn't.

Anthropic arguments are also used not only in relation to alternative laws of physics, they are also used in relation to alternative courses of events within our present laws of physics. For example, had the moon been a rather different size, it would have had a major effect on the potential for evolution of life as we know it on the earth. Even within our present laws of physics, we really have very little idea whether complex life is common in our universe, or unique to Earth. Whether our chemistry is the only kind of complex life, or if there could be quite different complex life that could evolve with a rather different chemistry in different conditions. Such is our very limited ability to work out what possibilities might exist within a set of laws of physics, that we have great difficulty doing it even with the laws of physics we know, where we have some data to go on. As for alternative laws of physics where we have no data to go on, well you'd have to be remarkably confident with our ability to understand the full range of their potential implications to say that you can really exclude everything. We really don't understand well enough how physics works to do that.

This wasn't originally about whether other universes would work, in the sense of being able to eventually give rise to something complicated enough to contemplate the nature of the universe it was in, but why we happen to be in such a universe which works, and it's obvious that we couldn't be in one which didn't.

[IvanV]

Particle physicists predict all sorts of extra families of particles, which we then fail to find at CERN.

Indeed they do. But perhaps in alternative laws of physics there are other organisations of energy which are not within the range of concepts that are what we would currently think of as a "particles". Indeed, there seems to be an awful lot of organised energy within our own universe we cannot identify, and perhaps it lies outside that range too. That might explain why particle physicists don't find it because they are looking for what they conceive of as particles. We really have no idea.

[IvanV]

As far as we know, there weren't any theoretical physicists during that time. This isn't about quantum mechanical observation, this is about there being something complicated enough in the universe to be able to contemplate the nature of the universe.

I didn't think that was the nature of anthropic argument you had in mind when you first brought it up. Nor, as far as I could see, did it seem to be what dyqik had in mind when he defined favoured anthropic principle.

[IvanV]

This wasn't originally about whether other universes would work, in the sense of being able to eventually give rise to something complicated enough to contemplate the nature of the universe it was in, but why we happen to be in such a universe which works, and it's obvious that we couldn't be in one which didn't.

Why do we happen to be in this universe? Just because we are. Because the particular history just happened to arise, from the huge number of alternatives, that happened to lead to that, and it is consistent with the known laws of physics. Why did those people over there win the lottery? Just because they did. Because the particular history just happened to arise, from the huge number of alternatives, that happened to lead to that, and it is consistent with the known laws of physics. I don't think there is any conclusion from such observations that acts as a constraint on anything we might be looking for, such as leptoquarks, which does not already lie in the known laws of physics, to try and get a better understanding of those laws, and explain the 98% of the organised energy in the universe we don't yet understand. That's why I call these observations vacuous. They tell us nothing that is not already encapsulated in the known laws of physics.

We obviously couldn't be in a universe with even slightly different conditions, let alone different constants or different laws. Who knows what might be there, both in principle and in practice? What does it matter for anything?

Any stronger kind of claim, that goes "Because us, therefore..." is religion. Or at least, I haven't seen a stronger claim of that nature that I didn't think was religion.

[dyqik]

As far as we know, there weren't any theoretical physicists during that time. This isn't about quantum mechanical observation, this is about there being something complicated enough in the universe to be able to contemplate the nature of the universe.

I didn't think that was the nature of anthropic argument you had in mind when you first brought it up. Nor, as far as I could see, did it seem to be what dyqik had in mind when he defined favoured anthropic principle.

The weak anthropic principle states (in a phrasing relevant here) is that we shouldn't be surprised that observations show a universe that is compatible with the existence of observers, or slightly more strongly, that we observe a universe compatible with the existence of us.

The "laws of physics" are statements about past observations that predict future observations, and so they necessarily require observations and observers, and a flow of time in the experience of the observers.

As an aside, I suspect that much of the difficulty with quantum measurement stems from the problem that we can only make laws of physics about observations on subsets of the universe, and reason about abstractions of the universe that divide it into experiment and observer.