New Physics!

[Kerbart]

One thing to consider is what you want to achieve with the diagram. To me it seems like a great "cheat sheet" for physics students, or a laminated companion to a book about particle physics. If the intention is to make an infographic about the standard model, this approach is a bit more challenging. The golden rule that I apply for charts is “if it needs explaining it's not a good chart,” and if you want to put the bar even higher: “if it takes more than half a second to see what the chart is about it's not a great chart.” That sounds incredibly hard, but Minard's famous chart of Napoleon's Russia campaign shows it's not impossible.

 

For an info-graphic for the general audience (me?) I'd consider something like this (please consider it as an example, not a guide like "how to make it"):

• What are the particles. What does the grouping mean?
• Lifespan - perhaps depicted on three of four parallel timelines (one for each family) - and a short caption why lifespan is important
• Size (if there's a relation to lifespan perhaps the two combined in a scatter plot
• Interactions

And then maybe at the bottom of the poster your "handy dandy here's it all in one graph" diagram, which would now be a lot easier to read when loaded up on the previous knowledge.

[NFUN]

11 minutes ago, sevenperforce said:

Having zero near one end but not quite at one end allows me to conveniently fudge the edge of the graph to add an infinity term, so that I can readily incorporate the electron and the up quark. Otherwise they would be off the chart by a factor of three.

 

Edited April 9, 2021 by NFUN

[sevenperforce]

10 minutes ago, Kerbart said:

One thing to consider is what you want to achieve with the diagram. To me it seems like a great "cheat sheet" for physics students, or a laminated companion to a book about particle physics. If the intention is to make an infographic about the standard model, this approach is a bit more challenging. The golden rule that I apply for charts is “if it needs explaining it's not a good chart,” and if you want to put the bar even higher: “if it takes more than half a second to see what the chart is about it's not a great chart.” That sounds incredibly hard, but Minard's famous chart of Napoleon's Russia campaign shows it's not impossible.

 

For an info-graphic for the general audience (me?) I'd consider something like this (please consider it as an example, not a guide like "how to make it"):

• What are the particles. What does the grouping mean?
• Lifespan - perhaps depicted on three of four parallel timelines (one for each family) - and a short caption why lifespan is important
• Size (if there's a relation to lifespan perhaps the two combined in a scatter plot
• Interactions

And then maybe at the bottom of the poster your "handy dandy here's it all in one graph" diagram, which would now be a lot easier to read when loaded up on the previous knowledge.

I want to replace the current diagram on the Wikipedia page for the standard model, which is hopelessly useless.

[SOXBLOX]

2 hours ago, sevenperforce said:

Which lines are difficult to see? I'm not asking to be snarky; I'm asking because I don't know. I've been making it myself so it's hard to figure out what the "right" version would look like.

Oh, no, that's fine, I understand! I was thinking the decay/oscillation lines, and the charge borders around the particles. Maybe if they were wider? 

Once you get it nailed down, you should sell it in poster form! Winchell Chung, from AR, sells his starmaps. I think some internet company prints them.

[kerbiloid]

6 hours ago, Kerbart said:

E=mc² without java-esque contortions

Algolesque or basicesque. No such operation in Java, but a circumflex in Basic, derived from vertical arrow in Algol.

 

***

Currently we have a clear understanding of most processes in the Universe.

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

[MKI]

22 hours ago, Kerbart said:

Not to mention the invention of superscript, making it possible to typeset E=mc² without java-esque contortions. But I digress.

I'm too used to using text-editors rather than rich-text-editors with all the fancy bells and whistles ;D

[sevenperforce]

Tagging @K^2 in this because his physics-fu may be sufficiently advanced from mine that he'll have the answer.......but anyone else is also more than welcome to chime in.

I've been working on updating the above infographic and it's coming along quite well (here's a nice picture of the progress):

Spoiler

I was trying to look up the neutrino oscillation frequency, thinking it could be a good analogue for particle lifetime. However, I couldn't find any mention of oscillation frequency or period anywhere. What I did find, on Wikipedia, were sine-wave probability distributions given with an x-axis in units of distance over energy, since the oscillation wavelength depends on particle energy.  (since neutrinos have a range of energies when they are detected): 

I also found another page which provided example conversions between neutrino energy and neutrino velocity. Obviously, velocity impacts distance traveled, which would impact the wavelength. So I wondered what the relationship was like. Did more energetic neutrinos have a faster oscillation period or a slower oscillation period? I did the math, and it appeared to indicate that more energetic neutrinos had longer oscillation periods. A 10 eV neutrino would have an oscillation period of about 3.6e-10 s, a 1 keV neutrino would have an oscillation period of about 3.6e-8 s, a 1 MeV neutrino would have an oscillation period of about 3.6e-5 s, and so forth. This seemed odd. Usually, more massive particles tend to decay/oscillate faster...though I thought that perhaps this was only applicable to rest mass, not relativistic mass.

However, then I realized that just as with the Frisch-Smith experiment that confirmed time dilation and special relativity, I would need to calculate the period in proper time, not coordinate time. So I solved for the Lorentz factor for each of the example neutrinos and divided. To my surprise, I got the exact same period for each: 5.01e-12 seconds.

Did I just discover a constant neutrino oscillation frequency?? I looked rather frantically at a bunch of different research and couldn't find anything that talked about neutrino oscillation frequency/period. That would seem to be a pretty straightforward bit of information, but I couldn't find it listed anywhere.

Help!

[Kerbart]

1 hour ago, MKI said:

I'm too used to using text-editors rather than rich-text-editors with all the fancy bells and whistles ;D

You were able to find the quote button. It's not that much different

Edited April 9, 2021 by Kerbart

[K^2]

@sevenperforce I'm pretty sure you're looking at bounds on neutrino oscillation frequency based on bounds on neutrino mass. If we knew the exact oscillation frequencies, we'd know masses of all the neutrinos, which would be big news.

As for the topic at hand, Higgs boson was basically the final nail into the coffin of any hopes that standard model is "nice and simple." Having just the U(1)xSU(2)xSU(3) symmetries with a boson field for each would be a sort of thing that I can look at and think this might be all there is, with just some oddities like the neutrino handedness and broken electroweak symmetry to be explained. With Higgs being confirmed to be the cause of the electroweak symmetry breaking, it's clear that there is no simple pattern to this representation, and if tomorrow they announce that they've found another field that interacts with SU(2)xSU(3) part, or a new SU(4) symmetry, or even one that doesn't fit the unitary group pattern, I'm not going to be surprised. The fact that we're finding out about it indirectly via anomalous magnetic moment measurements is just par for the course. Wake me up when there's a good candidate correction to standard model that fits new observations or if anybody comes up with something better.

[SOXBLOX]

You know, I can't help but think that these problems are to today's physicists as Mercury's orbital precession was to those of the 20th century.

[Jacke]

16 hours ago, SOXBLOX said:

You know, I can't help but think that these problems are to today's physicists as Mercury's orbital precession was to those of the 20th century.

You mean 19th Century, as General Relativity provided the needed correction to predict Mercury's precession accurately.

[wumpus]

1 hour ago, Jacke said:

You mean 19th Century, as General Relativity provided the needed correction to predict Mercury's precession accurately.

Nearly all the work directed at that involved looking for another planet inside Mercury.  Einstein's motivation was to extend his Theory of Relativity (then only Special Relativity) to show that the laws of physics held in accelerated fields of reference, instead of just at arbitrary fixed velocity.  Explaining Mercury precession just helped justify acceptance of a pretty extreme theory.

[SOXBLOX]

3 hours ago, Jacke said:

You mean 19th Century...

Nah, I mean 20th. Special Relativity was formulated in ... 1907? *checks Wikipedia* ... Oh, 1905. Still 20th century.

[NFUN]

special relativity has nothing to do with the precession of mercury

[K^2]

On 4/9/2021 at 6:16 PM, SOXBLOX said:

You know, I can't help but think that these problems are to today's physicists as Mercury's orbital precession was to those of the 20th century.

Sort of? I mean, we obviously can't know for sure until we figure out the problem. It can always be a case of, "Scientists discovered one more particle. The Standard Model now matches all experimental evidence perfectly." But if I was placing bets, I would definitely put money on things being way more complicated again.

That said, the level of fines at which you have to split hairs has definitely gone up a notch. A new theory wouldn't just have to explain the discrepancies. It would have to explain why we're getting such good results in many other experiments. Why is the anomalous magnetic moment of electron so darn close? It's not as simple as the case with Newtonian forces being just, "We never measured them precisely enough." We do have measurements that are precise enough in conditions where the match between experiment and theory is extraordinary. And then we have exceptions, which are few, but oh so annoying.

Another thing to highlight is that GR doesn't just invalidate all of classical mechanics. Conservation of energy and momentum are still there. You have to be careful with them in warped space-time, but the concepts are most definitely there. The difference is that we used to think that Newton's Laws are fundamental and conservation laws are a consequence. And now we know the conservation laws to be far more fundamental, being consequences of symmetries of space-time and fields within it. And because of the conservation laws and action, Newton's Laws fall out naturally as a good estimate to average dynamics. It's entirely possible that next major upset in physics will bring with it another paradigm shift, and maybe we'll find that symmetries are just approximate as consequence of something else, or whatever. But the fact that local symmetries are connected to local conservation laws is here to stay, and that means that we can't have something that's just completely new physics, it really has to be something that builds on top of what we have now. Not that this has ever been any different in practice. Just that now we have way more reason to expect this to persist.

Finally, there are some principles in physics that never change just because they aren't really physics. Allegedly, Einstein claimed that the one part of physics he'd be most surprised about ever changing would be thermodynamics. And I can't disagree. The basic principles were invented when people thought heat was a fluid. And entropy was just a funny consequence of the equations - a quantity that happened to be convenient to define to do math with. In that sense. But the underlying math is solid. We have substituted new concepts for what all the individual parts mean as our understanding grew, first with classical statistical mechanics, and then with quantum mechanics and condensed matter physics. But the math's just math. That isn't going anywhere. And so thermodynamics still works. We just know that heat is measure of internal energy of a system and entropy is a measure of disorder in that system in a way. All new physics, new understanding, but same thermodynamics.

I expect same of Quantum Mechanics. People always say that it's the one that looks the wonkiest, but that's just at the level of interpretation. Most of quantum theory is actually just math. Interpretations might change, we might get new underlying physics, completely new understanding of what a wave function is. But the math is still going to be the same. So we'll still have Quantum Field Theory of whatever's going to be the next big thing.

And this is the sort of thing in which I think we're in different place than early 20th century physicists. Everyone back then knew that change was coming. Experiment after experiment crashed against accepted notions. But what nobody had any idea of is how much of physics was about to change and what was to remain the same. We now have a bit of hindsight to work with, and I'm feeling much more comfortable about certain areas of fundamental physics enduring even if we have to throw Standard Model and much of General Relativity into the garbage bin.

4 hours ago, NFUN said:

special relativity has nothing to do with the precession of mercury

Fair warning, this is me just being in maximum pedantic mode, but I wouldn't phrase it like that. Special Relativity is a special case of General Relativity, so it certainly has a few things to do with precession of Mercury. But yes, SR is not sufficient to explain precession. General Relativity and Schwarzschild solution of Einstein Field Equations for vacuum are necessary to adequately describe motion of Mercury. And yeah, that came about a bit later. Specifically, Schwarzschild's work was only published in 1916.

[NFUN]

special relativity has nothing to do with the precession of mercury*

 

*for certain values of nothing

[SOXBLOX]

13 hours ago, K^2 said:

But yes, SR is not sufficient to explain precession. General Relativity......

Oops. I stand corrected. I guess I misread the Wikipedia article.

[JoeSchmuckatelli]

21 hours ago, SOXBLOX said:

I misread the Wikipedia article.

Something I do on a regular basis! 

[sevenperforce]

On 4/9/2021 at 7:12 PM, K^2 said:

@sevenperforce I'm pretty sure you're looking at bounds on neutrino oscillation frequency based on bounds on neutrino mass. If we knew the exact oscillation frequencies, we'd know masses of all the neutrinos, which would be big news.

Well, the energy-to-mass relationship is definitely dependent on neutrino mass. That's basic. But it's the graph above, giving the oscillation frequency in units of distance/energy, which seems to be the key. If the oscillation likelihood is observably sinusoidal with respect to distance/energy, then that means there is an underlying oscillation frequency which is sinusoidal with respect to proper time, independent of particle energy.

That seems like it would be a big deal. But it's not stated explicitly anywhere. 

[K^2]

2 hours ago, sevenperforce said:

Well, the energy-to-mass relationship is definitely dependent on neutrino mass. That's basic. But it's the graph above, giving the oscillation frequency in units of distance/energy, which seems to be the key. If the oscillation likelihood is observably sinusoidal with respect to distance/energy, then that means there is an underlying oscillation frequency which is sinusoidal with respect to proper time, independent of particle energy.

That seems like it would be a big deal. But it's not stated explicitly anywhere. 

Well, yeah. But that's absolutely obvious to anyone who works in particle physics. I mean, it took me a moment to even figure out what you are finding surprising about this.

Think about it this way. Lets suppose that neutrino oscillation frequency actually depended on neutrino energy. That would imply that in neutrino's rest frame its oscillation frequency changes depending on how fast the neutrino's rest frame is moving relative to some reference frame. Id est, you'd be measuring the absolute speed of neutrino.

The fact that physical quantities cannot depend on energy of a particle other than by Lorentz factor is fundamental result of Special Relativity and gets knocked into your head when you study particle physics within the first few lectures. This is your basic assumption that you get used to applying without even thinking, because it goes for absolutely everything. Frequencies, decay times, etc.

In fact, the reason flavor oscillations were a big deal is precisely because of that. The part people rarely add, because it's obvious to everyone in the trade, is that if the oscillations are being measured at all, some amount of time passes in neutrino proper frame. You can't have oscillations if you don't have proper time. And you can't have proper time if you are moving at light speed. So yes, observing oscillations means neutrinos have mass, and if you could measure that frequency precisely at different energies, you'll know the exact mass of neutrinos. Even if we didn't have all the rest of Standard Model, simply knowing the Lorentz factor gives you energy-to-mass ratio, so you'll know precise mass of neutrinos. This is just goes-without-saying kind of thing in particle physics.

[sevenperforce]

22 minutes ago, K^2 said:

The fact that physical quantities cannot depend on energy of a particle other than by Lorentz factor is fundamental result of Special Relativity and gets knocked into your head when you study particle physics within the first few lectures. This is your basic assumption that you get used to applying without even thinking, because it goes for absolutely everything. Frequencies, decay times, etc.

In fact, the reason flavor oscillations were a big deal is precisely because of that. The part people rarely add, because it's obvious to everyone in the trade, is that if the oscillations are being measured at all, some amount of time passes in neutrino proper frame. You can't have oscillations if you don't have proper time. And you can't have proper time if you are moving at light speed.

Ooooooooh there it is. That's the bit I was missing.

I wondered why flavor oscillation required mass but I didn't connect that anything which requires the passage of time cannot happen to something massless.

So if we measure a sinusoidal neutrino oscillation wavelength of ~1067 km/GeV, then we have a relationship between neutrino mass and neutrino oscillation rate. If the mass is on the order of 0.2eV/c², then the proper time oscillation period is on the order of 5.02e-12 s. 

I suppose that at these energies, there are huge problems with trying to even design an experiment to determine the proper time oscillation rate. 

While I have you -- I've gotten conflicting statements on whether the three flavors of neutrinos are their own antiparticles or not. What's the current state of our knowledge here?

[K^2]

52 minutes ago, sevenperforce said:

While I have you -- I've gotten conflicting statements on whether the three flavors of neutrinos are their own antiparticles or not. What's the current state of our knowledge here?

In the way particles are usually interpreted in Standard Model, a particle has to be massless to be its own antiparticle. There's also the fact that neutrinos come with predominant handedness, and that strongly suggests that neutrinos and antineutrinos are distinct. (Otherwise, we'd expect equal distributions by CPT.) So there is strong indication that they probably aren't their own antiparticles. If we find an experiment that strongly suggests they are, we'd have some explaining to do.

To put it in classical terms, it'd be a bit like discovering that Saturn came from outside the Solar System. We'd have to do a lot of new research to figure out how the heck did that get past us, and come up with entirely new models for early Solar System formation, but it wouldn't change our understanding of gravity and orbital mechanics.

[MKI]

2 hours ago, K^2 said:

To put it in classical terms, it'd be a bit like discovering that Saturn came from outside the Solar System. We'd have to do a lot of new research to figure out how the heck did that get past us, and come up with entirely new models for early Solar System formation, but it wouldn't change our understanding of gravity and orbital mechanics.

Or it was aliens 

 

I watched a youtube video that got me closer to a "ooohh" moment for how these new findings impact our current understanding. So I feel less "lost" on the topic. 

[HebaruSan]

On 4/11/2021 at 5:49 PM, SOXBLOX said:

Oops. I stand corrected. I guess I misread the Wikipedia article.

If it's any consolation, the switch from SR to GR gives the "twentieth century" point you were originally defending 11 more years of breathing space.

[Gargamel]

Sixty symbols just did a pretty good video on this. 

At least good enough for me to get a better idea of how the expirement works, and how they came to their findings.     Part of me wonders though, since they’re using some of the same equipment in both excitements, if there is some instrumentation problems leading to these results.