"I see a clock, but I cannot envision the clockmaker. The human mind is unable to conceive of the four dimensions, so how can it conceive of a God, before whom a thousand years and a thousand dimensions are as one?" -Albert Einstein
It would have revealed a lower layer of higher understanding.
No one has been able to calculate the mass of a quark:
"Nobody has seriously calculated theoretically a quark mass from first principles. So there is no issue of agreement with experiment. They are parameters in experimental fits, but sometimes remarkably consistent across a broad range of experiments-- and the QCD/EW calculations using them as inputs. If someone pretends to know their origin, he/she is bluffing."
> apart from the fact that dark matter predictions have been contradicted by increasingly sensitive experiments over and over and over
My impression is that many physicists would disagree with this characterization entirely, and that they're eagerly working to constrain what it is or isn't. Ruling out big classes of phenomena that could be responsible for the things we observe isn't "contradicting" the predictions in the sense implied.
Particle physicist here. I've worked on direct detection DM experiments in the past, and personally know some folks who work on the LZ experiment. That direct detection experiments, such as LZ, have not detected a signal does not contradict any predictions.
Indeed, relevant to what an experiment like LZ might see, there really isn't much in the way of "predictions" which can be "contradicted." What we have at this point are mechanisms to calculate the interaction rate _given at least one free parameter_. If we were to detect a non-zero rate, then we would "know" the free parameter of a single-parameter theory underlying that calculation. If we were to continue to detect a non-zero rate, then we would try to do so using different materials, and look at the time dependence of the rate (or, really, the dependence of the rate on the Earth's direction of travel in our local galaxy). That would help us choose between different theories, pin down the free parameters, and confirm that what we're seeing is consistent with "heavy stuff just sitting out in the universe."
But, from a particle physics perspective, right now there are no predictions to contradict - just an opportunity to detect something.
I'd normally agree with you, but in the particular case of dark matter particles something still smells fishy. The theories that the predicted cross-sections are based on are just too flexible and numerous. I'm not sure how much we gain from ruling out yet more. What if there are in fact no weakly interacting particles? At what point do we decide that enough has been ruled out to start looking elsewhere? Like plasma dynamics or something (please don't shoot me if this is too silly to even contemplate).
Reprioritization of direct experimental searches for dark matter is already happening. WIMPs are by no means being abandoned, but because we are closing in on the neutrino fog background (which is mentioned in another comment), it's been recognized that to myopically cling to the same kind of experiment which dominated the 2000s and 2010s is not a strategic move (both from the "we expect to see something" and the "responsible use of tax dollars" perspectives).
For example: axions, an alternative DM candidate mentioned in another comment, have seen a significant growth in attention in recent years, and the usual detector technology for axion searches is currently being refined and scaled up, from benchtop-scale, dedicated experiments to lab-scale, wide searches.
At the same time, different groups which have developed past WIMP detectors are merging to collaborate on the larger, next-generation detectors. And there is R&D and prototyping happening to create detectors which, although looking for WIMPs, are sensitive in entirely different mass ranges than those of yesteryear.
That's just how particle physics research works. You build a detector that is designed to detect things with specific properties. You run the detector. Did you find the thing? If so, great, if not, well, that's the way the cookie crumbles. Either way you write a paper and you build the next detector.
The Higgs boson has numerous experiments exclude numerous mass ranges excluded before it was finally found.
> At what point do we decide that enough has been ruled out to start looking elsewhere?
"We" don't make that decision. The various institutions who pay for these things decide, one by one, that they're going to fund some thing that sounds more promising instead.
It does kinda suck that there's something there in the universe that is perniciously difficult to see--in fact, that's how it's defined--but that is so important in the way the universe works that we can't simply ignore it. But this is the universe we're given, so this is the universe we'll run experiments on.
I think the point is the model though - if a system's behavior can be modeled/described classically, it's a bit silly to to call it a "quantum" system in the same way that it's reductive to say Biology is just applied particle physics. Sure, but that's not a very useful level of abstraction.
If you want to understand the transition between a fundamental theory and its effective description in some limiting regime, you need to be able to describe a system in the limiting regime using the fundamental theory. It's not "silly" to talk about an atom having a gravitational field even if it's unmeasurably small (currently).
Lol, so you've got a working theory to bridge the quantum and classical worlds? That is, you've figured out how to make general relativity and quantum mechanics emerge from a more fundamental theory? Somebody get this person a Nobel!
We're at the phase where we know the world is quantum, but we also simply don't have the ability to bridge that set of observable phenomena to what we know about macroscopic things. That's what makes this exercise "silly".
No need to be sarcastic. We are trying to develop ideas and have a conversation
We are not trying to prove who is right and who is wrong
Regardless of whatever the mainstream agreement in physics might be regarding a preferred model for reality, everyone experiences reality directly, without any need for science or math. And they can express those experiences and ideas in their own way
If you don’t agree with someone else’s ideas, please just explain why politely, and also maybe even try to understand their point of view. What would things look like if they were actually right? How might theirs be a good idea?
I'm not trying to be mean, it just struck me as kind of a funny position.
"If you want to understand the transition between a fundamental theory and its effective description in some limiting regime, you need to be able to describe a system in the limiting regime using the fundamental theory"
Like, that's well and good, but in general we just can't do that without hand-waving, period. This is true all over the place (biology/physics, psychology/neuroscience/physics). It's sort of true, but not in a useful way.
What does that even mean, and how is it a response to my point that choosing an appropriate level of abstraction for the problem at hand is a good idea?
> in general we just can't [describe a system in the limiting regime using the fundamental theory] without hand-waving, period...It's sort of true, but not in a useful way.
And I am saying that it in fact can be done, and has been done, in physics and math in a very non-hand-waving way. One can show rigorously when a certain abstractions is accurate.
Well... sure, but I think you're still almost purposely missing the point. Take this example - can we prove that a system of differential equations emerges in a meaningful way from discrete systems? Yes, obviously. That's a far cry from the OP's "if you think about it, all things are quantum", which is where this thread started and what I'm talking about.
It also illustrates the actual point pretty well - when you have a good set of differential equations that describe observed phenomena, that higher level of abstraction gives MORE insight into the processes at play, even when we know that it emerges from something more fundamental. Only when that model is a poor approximation do we need to appeal to the more fundamental regime (or when that fundamental regime is what we're studying).
If you think that fact that levels of abstraction give insight is a rebuttal to the OP, you don't under what he's doing. Understanding how the fundamental theory reduces to the abstraction (1) allows you to precisely know the limits of the abstraction and (2) allows you to port knowledge you have about one side to the other.
Like, this comment of your is a great example of the sort of confusion that arises when you don't understand the non-relativistic limit:
> Lol, so you've got a working theory to bridge the quantum and classical worlds? That is, you've figured out how to make general relativity and quantum mechanics emerge from a more fundamental theory?
You're confusing the quantum-classical transition with the quantum-gravity to classical-gravity transition. (People understood the relativistic-Galilean transition before they understood the QFT-classical-field-theoy transition.)
I teach people who thought this way, and later decided to enter a career that requires basic data analysis literacy. They struggle with things like order of operations, which is incredibly frustrating. Teaching math up to the high school/introductory college level is about building foundational skills that can be applied in different directions. Will they need to apply trig identities? Probably not, but the process of getting there in high school is good for their minds and foundational abilities.
So yes, I'd personally say we should expect people to "keep up in math".
That's not necessarily true. If Dark Energy is a property of the vacuum state of space and it's a force acting opposite of gravity, then the further apart those objects become then the more those objects will accelerate from one another. That's what leads to an accelerated expansion of the universe.
That doesn't change the fact that gravity can overcome Dark Energy. To wit, the Andromeda and Milky Way galaxies are on a collision course. Yes, Dark Energy is working to drive those galaxies apart, but gravity is winning and the closer those galaxies get to each other then the strong gravity is going to become.
Gravity gets stronger as the distance between objects decreases, Dark Energy gets stronger as the distance between objects increases. That is if Dark Energy is a property of spacetime. Since we don't know what Dark Energy is we can't say for certain, but it appears to be a property of spacetime and if that's the case then this statement is true.
The cyclist hate is really demoralizing sometimes. Like, I'm out here trying to enjoy life and be healthy and people think it's funny to joke about murdering me.
I have no hate towards them, what I said what tongue in cheeck. After relying on two wheels (motorbike mainly) for about 10 years, I get the cyclists viewpoint. It's certainly not cool to joke about murdering anyone, cyclist or not.
It's just that ... they do tend to flaunt the rules here in Brussels. It's partly clear why (losing momentum on a bicycle sucks) but also extremely stupid to throw yourself (and your two kids on the back) in front of 2000KG of metal moving at speed, expect that metal so accommodate you (something no sane motorbiker will do) and if not start screaming and punching the metal.
I get annoyed at cyclists who ride irresponsibly too - I also live in a place where people HATE cyclists beyond any and all reason, and in general I think we're all being failed by our infrastructure first and foremost.
You didn't joke about killing cyclists, but that's where the culture is where I'm from, so I'm touchy about it.
I've long believed that riding a bike should require a license and that cycling laws need to be part of getting licenses for both the cyclist and drivers. Part of the problem is, most people don't actually know the laws for operating a bicycle, including most cyclists. I know this is an unpopular opinion.
It's exactly that. The problems that exist with cyclists and people riding steps does not exist with people riding motorbikes for which you need a license.
I love that attitude - we have a safety issue, so let's victim blame and ignore the infrastructure issues, poorly trained HEAVY MACHINERY OPERATORS, safety-hostile vehicle design, and generally enormous subsidies for using cars everywhere.
It also leads to restrictions on walking "for safety". For instance, note attempts in Ireland to make it illegal to walk at night without high visibility gear.
Cars ruined cycling. The only way to avoid cars is to use a car yourself. The problem is then you need to do pointless supplementary exercise lest you become an incapable blob like they are. Driving to the gym it is then.
Maybe this is just me, but combining exercise with commute has never been practical for me. I still cycle to work, but I don't do it for exercise, only because it happens to be the fastest method in my present circumstances.
But still using it as an example, on my way to work I take the easiest, least hilly route to avoid any sweating as possible. On the way back, I take the most downhill route possible because I still want to wear the same pieces of clothing (say, a jacket) without having to wash it daily. In short, I don't go all out. Result - I don't lose weight at all nor has my physical fitness improved much.
Versus if I engaged in "pointless supplementary exercise", I do go all out, and after 30 minutes I'm all drenched in sweat.
My present circumstances don't allow it, but I imagine if I could drive the same distance to work, I would save about 30-60 minutes which I could in theory use to engage in an all-out workout.
I saw a funny presentation where Doug Bates said something like: "This kind of evaluation opens the door to do many strange and unspeakable things in R... for some reason Hadley Wickham is very excited about this."
In Dyalog APL you can set the index origin with ⎕IO←0 (or 1) and there are many ways in which this can bite you. In Lua, and I think Fortran, you can specify the range of array indices manually.
Is anyone aware of a YouTube or tutorial series that goes deep into the graphics stacks for Julia? I can make some plots, but I feel like I'm missing the deeper understanding of what's going on that I have with R base graphics.
The presentations and workshops about Makie.jl from the last few JuliaCons are pretty good. All recordings from JuliaCon are available at the official Julia youtube channel.
