Which is exactly why people still work on things like Bohmian Mechanics/Pilot Wave theory[0, 1].

[0]https://en.wikipedia.org/wiki/De_Broglie%E2%80%93Bohm_theory [1]https://en.wikipedia.org/wiki/Pilot_wave

There's a lot of really strange stuff going on with QM and ST, even tho Brian Greene works primarily on ST he did somewhat coined the concept of the "giant leap" that to some extent theoretical physics has run off way too far from anything that can be proven using experimentation.

>Physics has been stuck on this problem for almost a century now. Philosophy won't help.

Philosophy does help, infact it might be the only thing that would help in it's essence philosophy is about how you approach and solve problems, and more importantly how you think about them. It might need be that we do need a major philosophical change in the world of theoretical physics and start thinking about QM and the universe in general in completely different matter.

There is a lot of natural bias that pushes your thinking into a very predictable path and this plagues theoretical physics just like any other field if not more. The bleeding edge of theoretical physics, especially in the past 60-70 years has really shifted towards almost the metaphysical regardless of how much elegant math there is behind it.

What is this idea that making the math prettier or more elegant is not important? That's like saying a new algorithm isn't important; new math or models make problems potentially tractable that aren't now.

All of our math is an attempt to represent things or ideas. The most important thing I learned in my physics education was how to read math as a metaphor for putting together things I understand into a picture of a thing I don't understand. But I don't think anyone serious thinks that their math is "true", such an assertion just makes no sense. The point of it is to find new ways to approach the evidence to see if it gives some different metaphor that wasn't obvious before.

I don't know enough modern physics to have an opinion on whether this is the case for cosmology or string theory, but I do know that in recent history just formulating a problem slightly differently can suddenly make the solution fit in the same framework as a known simpler problem. Not unlike things I read all the time about algorithm research at all, right?

Teaching and understanding models is predicated highly on metaphor, it's much easier to explain for instance that MRI works via a quantum effect that has the same math as a harmonic oscillator than it is to just... dive in. The model isn't the universe, but humans live by metaphor and so the model is important.

Which is perhaps not the point you were trying to make; I don't know enough modern physics to know whether a critique of these new areas as purely fantastical is justified, but it's also pretty fantastical to think of a particle in a box as if it were like a weight on a spring. Who am I to say that something about this approach can't make a currently intractable, approximate, or computational impossible problem solvable with time?

The danger with math is that it can prove its own truths based on its own internal rules, so there's a temptation to believe that whatever you can describe mathematically describes something that actually exists in the real world. But until you've tested it experimentally, you don't know whether you're describing a total fantasy world, like The Lord of the Rings, or something actually real, but boring, like an apple. Just because you've proven with mathematical certainly the existence of hobbits doesn't mean you'll actually find any.

> The danger with math is that it can prove its own truths based on its own internal rules...

Actually, there's a theorem about that ;) Godel's Incompleteness theorem.

I would describe the problem more like: The new model matches the old model in almost everything (because we've observed a lot). But the math works out quite nicely if itty bitty particles behave this way when exploded at super high temperatures. We have a hard time watching those particles explode, so it's not really tested. Either way it works out, it's not really going to matter for anyone who doesn't explode tiny particles.

Given that GP was discussing publicly, on a technical internet forum, the relationship between mathematical provability and truth/existence, don't you think it likely that GP was aware of Gödel's Incompleteness theorem? My concern is that the "actually", and the smiley face, seems, to me, very patronizing. I really don't mean to be attacking you for a small point of etiquette, and I also acknowledge that the main purpose of this thread (the nature of reality) is a bit more important, but I do make this point sincerely. This is something I find a real problem when discussing things with software engineers. I personally hate the feeling of being patronized in public, or of someone replying in public with the implication that I was not aware of something which I am perfectly well aware of. I'm not claiming that the GP is an expert on the Incompleteness Theorem, and I'm certainly not, but that "actually", and the smiley, sound and look awful. We should assume that others are competent and knowledgable on the subjects they talk about until given evidence to the contrary.

I believe you've misconstrued d13's intended meaning. In short, what they said is something can be mathematically consistent without being physically realistic. GIT is not really pertinent here.

Gabriel's Horn is probably more appropriate: https://en.wikipedia.org/wiki/Gabriel's_Horn

I'm skeptical that theoretical physicists disagree. If anyone would be aware of these dangers, I would imagine it to be them; these are incredibly smart people! I only even got an undergraduate physics degree and this stuff was all quite obvious. Which isn't to say that arguing about which metaphors are likely to bear conceptual fruit isn't worthwhile, but even with much more physics education than most I would never deign to enter such a debate myself. The people doing the work definitely know what they're doing and I definitely don't, so to presume otherwise is weird to me.

I worry that it is the pop sci presentation of physics that non-physicists look at and think wrongly that the actual people carrying out the work are blinded by training bias (which is true for anyone, but I think far less true for experts in the field than otherwise) when in fact it's just the authors of pop sci articles and books who are ignorant of the difference between metaphor and reality. These are people who are paid to figure out how to think differently about their questions, they're not just following conventions and calculating pi to more decimal points.

Is an encryption algorithm "real"? Is the process used in proving a theorem "real"? Is the way that we model an atom "real"? No, of course not; they're all ways to represent an idea/observation through metaphor by breaking down a problem to make it look more like problems we already know how to solve. And if you just decide to approach the metaphor for understanding that idea differently, you can get massively more tractable problems.

As an example, a friend of mine in undergrad was studying crystalline domains in metals and wanted to find a way to understand better the relative misorientations of neighboring crystals in three dimensions. The metaphor as written strongly suggests that the right approach is some manner of statistical approach with a random variable representing orientation that can then be statistically analyzed to provide a misorientation distribution, but the problem is generally intractable in 3 dimensions whereas in 2 dimensions it's fairly straightforward math that way.

He instead decided to represent the crystallites in four or maybe five dimensions, which by so doing he was able to show that the math looks the same as that used for adding angular momentum using Clebsch-Gordon coefficients derived from quantum mechanical spin coupling. And found that by so doing he could turn a statistical problem into one with a closed-form solution that was quicker and easier to calculate in more sophisticated cases. With apologies if I'm explaining it wrong, this one never was quite comprehensible for me, he was far better at math.

Does he then think that crystallite orientation is literally quantum mechanical spin? Of course not. Does the math produce a testably distinguishable result? No, of course not; it should be the same result. But is it likely some future scientist with greater understanding of quantum spin coupling might be able to conceptualize the system more deeply? Definitely! This example is hardly unique.

So my point is that representation and metaphor matters, even if it's not a testably different result. To say that it doesn't matter to me seems to be saying that the current model itself is real, when it's not either! There's no fundamental reason to favor one over the other if the results predicted are the same, other than personal preference, ease of manipulation, or ease of conveying the model/metaphor to future students.

By encouraging different metaphors for the same system, you enable future scientists to be taught those alternative approaches so that they have a bigger toolbox to approaching some yet unknown future problem. We're just humans, and everyone looks at things a bit differently; none of us with a clear picture of what's really "real". Much like how there are a half dozen different approaches for quickly sorting a list, some are more intuitive or powerful or quick to execute than others.

Incredible smart people have a tendency to fall in love with there ideas and the beauty of the created concepts. Im pretty sure that physics as a field has the same problem with architectural astronauts as software engineering has.

Im not criticizing hard working mathematicians and physicists like your friend- the solution he found sounds rather elegant, and the results are testable. And you are right about having no dogmas when it comes to approaching the riddles of tomorrow- and yet, if all work you do is untestable- you are not a scientist.

There are people whose job it is to make pretty math, they are called "mathematicians" ;-) So much of early physics, be it thermodynamics, electromagnetics, classical mechanics, is genuinely beautiful and elegant. I can see why quantum physicists would strive for that ideal as well. But at the end of the day I agree that physics should favor creating testable predictive models over developing untestable, elegant ones.

I'm sure most theoretical physicists would call themselves mathematicians. I don't agree physics should favour creating testable predictive models, because who are we to say what's testable in the future? Take the theory of relativity, for example. Would you have stopped Einstein et al from researching it, just because it wasn't testable at the time?

In my opinion, physics is and has always been about answering the big questions, the how's, the why's of our existence. That new technology sometimes comes out of it is a bonus, not the ultimate goal.

If that is so then why don't we just accept the religious answers to these big questions? Some supernatural entity is in the control of everything that's the answer and we are done. The goal of any science should be to answer questions such that those answers can help us solve the problem humanity faces and not just make us feel proud sitting in our chairs that we know answers.

I think you are generalising my comment quite a bit, it was just a reaction to the poster above.

We are never "done", that's kind of the point I was trying to convey. I completely agree that we should use science to help us deal with our current problems. Once we understand more about our world and ourselves, we will automatically get better at solving them. I'm just against the whole short-term, instant results way of thinking.

Although difficult to test, there were features that were in theory testable! AFAIK this is currently not true with ST

I didn't say that math is not important, but you can also dig yourself into a hole with it, there are quite a few competing theories all of which have a strong mathematical basis because you develop the math to explain your model of reality especially when you cannot gain sufficient evidence from experimentation.

The overall point was which I might not have expressed fully is that there is in my opinion too much bias in the field of theoretical physics, and to paraphrase Brian Greene again we took a giant leap and probably skipped a few steps and no one seems to want to look back and see if we missed something.

I think one of my favorite quotes that somewhat describes this view is by Rudolf Peierls: “In recent years the debate on these ideas has reopened, and there are some who question what they call ‘the Copenhagen interpretation’ of quantum mechanics’ - as if there existed more than one possible interpretation of quantum mechanics.”

And I think that this view is antithetical to the advancement of current physics, and sadly this bias is instituted even unintentionally in most new physics students especially those who take physics as part of their degree in CompSci/Engineering.

I totally get your point, that getting stuck in a framework can make it harder to get out of said framework, but I also have every reason to think that the experts in the field (which may well include you) are aware of this trap and spend a huge amount of time trying to get out of it.

But I'd also expect that people making new theories be intimately familiar with the current ones, right? It would be silly to expect someone to come up with hamiltonian mechanics for the first time without having ever been exposed to newtonian mechanics, even though both give the same answers to every problem. Yeah, thinking outside the box is always super hard, but you have to at least deeply understand the box before you can know enough to replace it. I definitely don't understand this particular box, but I feel it's reasonable to assume that those that do are trying their darndest to escape it -- if for no other reason than fame if successful.

It might but we've been generating many imaginary solutions without a lot of take-home benefit for a while now. ST has had an extraordinary run given how useless it's been, especially since it's sucked up money and time that might have been better spent on real science.

Actually, many people believe that math is "true", and in many cases they believe that math is more real than the physical universe. The position is called Platonism, in its older form, though Kant has his own spin on the idea.

But there are many incompatible mathematical systems, and only at most one of them could describe the actual universe.

As I understand ST, by choosing particular parameters you can make it predict (more or less) anything. If so, what does it mean for it to have made a prediction?

Very insightful comment, thanks for sharing!

I personally think pilot-wave theory is about to make a serious comeback in this coming decade. It certainly explains the exact same phenomena but it doesn't resort to any spooky stuff except action-at-a-distance. I'd rather embrace nonlocality than the crazy many-worlds stuff. We are just used to locality, why does it have to be an axiom? Seems like it could just as well be a result of the law of large numbers, same as any other macro effects in QM. That is, there is just a very high correlation that results in locality. Same as not being able to pass through a wall, or schrodinger's cat not appearing in the macro world.

I do too, i just find the concept considerably more elegant, and to my own feeble mind considerably more intuitive. The Pilot Wave theory has also been getting some experimental support recently [0], and while it's still fairly early, it still beats string theory. All the work in nonlocality also helps in my opinion the Pilot Wave theory to become relevant again, we have too many experimental data for use to disregard it and none of the other solutions that incorporate nonlocality seem as elegant to me. I too think that the universe is most likely deterministic, and has strong realism which saves us from having to deal with the observer concept in QM especially some of the weirder interpretations of it[1].

P.S. If anyone is interested in PWT one of the best materials I've seen is a series of lectures by Mike Towler of Cambridge University[2]. It's probably one of the better constructed lectures I've seen of QM in general, it hits the very rare sweet spot of being actually informative without falling into the realm of popular science while not requiring PHD level physics to follow (infact depending on the country you went to high school if you did cover QM in year 10-12 it's almost everything you need).

[0]https://www.quantamagazine.org/20160517-pilot-wave-theory-ga...

[1]https://en.wikipedia.org/wiki/Von_Neumann%E2%80%93Wigner_int...

[2]http://www.tcm.phy.cam.ac.uk/~mdt26/PWT/lectures/bohm1.pdf (change the url from bohm1 to bohm8 to get all the slides)

You should be careful with the language. Pilot Wave Theory gives rise to the quantum formalism. Anything predicted by standard quantum mechanics is a prediction of PWT.

Of course, the PWT viewpoint may suggest new ideas and understandings; it is, after all, what led Bell to his inequality and thus spawned all of the entanglement uses including quantum cryptography. But it gets reincorporated into standard quantum mechanics.

None of that really matters. People reject PWT because they want to reject it. There have never been any good reasons. It is an extremely simple theory that answers the questions.

If it gets accepted in the future, it will only be because of a new generation being more willing to embrace it.

At first the physicists said it was impossible and then when it was obvious that it was possible, they said it was too trivial. This is a hallmark of reason being used to justify an already decided on outcome.

It is also not in conflict with string theory. One could imagine string theory actually having strings that evolve. This would be the spirit of PWT applied to that realm.

I'm curious what language would that be? I didn't thought i made any strong statements.

Yes in it's essence PWT doesn't conflict with the concept of strings (nothing really does), I'm not so sure that I doesn't conflict with the leading "complete" string theories out there today.

"getting strong experimental support" makes it sound like it is experimentally distinguishable from standard quantum mechanics.

Can there ever be an experiment which proves which interpretation of QM is correct? I have heard that there isn't but I find that so weird. Don't they have any difference in their predictions at all?

GRW (spontaneous collapse of the wavefunction) is a different theory and theoretically experiments could get good enough to prove it wrong.

But most interpretations have the same statistical predictions as standard QM. The standard Copenhagen setup can be argued to not actually be a theory (the split between quantum and classical in a fundamental theory is an absurdity since the classical is made up of quantum ), but assuming that an interpretation is clear enough to be called a theory and has the same statistical framework as standard quantum mechanics, then experiments will not distinguish them.

The different interpretations, however, may lead to different insights for extending the theory. And in that game, one may pull ahead of the other. For example PWT inspired Bell's results. PWT can also explain the impact of the topology of configuration space convincingly since the configuration is a fundamental part of the theory. It leads to many insights that the others just have to assume.

GRW with a flash ontology has a relativistic version with no foliations. So that's cool.

Ah, i see now, well that wasn't my intention at all.

IMHO, PWT can be proved with two slits experiment and FTL electrons: they will behave like particles, because their wave will be unable to interfere with itself.

PS.

To clarify, if double slit will be put in a medium where speed of light is much slower, then there will be a speed, when electron with that speed will stop behaving like wave. This point will be depended on speed of electron, speed of light in medium, and distance between slits.

Is that even possible to construct? won't any dielectric media interfere with the wave/particle duality regardless if the speed of light is slower or faster than the speed of the electron in it?

Yep, it will be hard to conduct.

IMHO, it still possible to adjust slit experiment in such way, that slight increase in speed will break interference, i.e. at speed X electron will behave like wave, but at speed X+1 electron will behave like normal particle.

> I'd rather embrace nonlocality than the crazy many-worlds stuff.

Why do you describe many-worlds as 'crazy'?

Edit: to whoever down-voted me, this was a serious question.

What does it mean if particular probability for x vs y is an irrational number? Can you really have a number of universe forks counted in something that isn't integers?

If you don't really have independent universe forks but something physically continous, what mechanism makes us seem to only observe a single independent branch at all times?

Given the assumption of quantum foam (from the uncertainty principle) at the Planck length + relativity (the Planck length isn't constant like the speed of light, every observer measures it differently relative to others), how many universe branches are really created every picosecond in every Planck length (volume) across the visible universe?

IANA physicist, but my layman's understanding was that under many-worlds the universe doesn't actually fork. Rather, the superposition of states observed in things like the double-slit experiment applies to all particles all the time, including the ones in our brains. When we observe a system undergo an apparent collapse of the wave-function, what's actually happening is that we/our brains have become entangled with that system, so each of our brains' states becomes correlated to one of the system's states. To a consciousness generated by one of those brain states, it appears that the system under observation has undergone a collapse; however, the result of that collapse appears different to each such brain state.

At least, that's what I took away from this:

http://www.askamathematician.com/2010/10/q-copenhagen-or-man...

and this:

http://www.askamathematician.com/2011/11/q-according-to-the-...

Wow. At some point this theory just becomes so complex it will collapse like the wave functions it talks about...

Seriously, to my also-completely-laymen mind this seems adding epicycles to me.

Nonlocality means there may be interactions between particles across space. That seems reasonable because what we intuitively think of as space and time may just be strong correlations. Causality etc.

But if at every moment you literally have an infinite amount of worlds branching off, then that's vastly bigger than one world in which interactions can be nonlocal. It violates everything from Occam's Razor to practicality.

The question of why time is non reversible can be answered by saying that entropy of a system grows with time, which is a consequence of simple statistics. But with many-worlds you have branching in the forward time direction? Can you explain anything about it?

> if at every moment you literally have an infinite amount of worlds branching off

As I said in my reply to Natanael_L, I was given to understood that the idea of worlds branching off was a misapprehension of the many-worlds interpretation. But I'm prepared to be corrected.

> I personally think pilot-wave theory is about to make a serious comeback in this coming decade.

Which is a shame, because John Bell of Bell's theorem was already a fan back in the 60s. He correctly labelled non-locality as the fundamental problem of QM, where other interpretations just let them gloss over this difficulty by labeling such questions "non-physical".

But realistically, I think information-theoretic formalizations of QM will simply gain more popularity in rather than something like de Broglie-Bohm. There's simply too much anti-realism sentiment in the physics community for it to gain much traction.

Yeah that and pilot wave has some elegancy to it that finds simmetry at so many other scales. So in other words as long as them will all be interchangeable and unverified, I'll fanboi for pilot wave.

> Philosophy does help, infact it might be the only thing that would help in it's essence philosophy is about how you approach and solve problems, and more importantly how you think about them.

I'm genuinely curious to know how you think any post Frege philosophy helps. At best philosophy can help prevent research/effort being expended in plausible non-sense; but certainly not in the sense of providing a positive result or foundation for one (which is to my understanding what those doing ST are ultimately seeking).

I'll also take the time here to gripe about post-wittgenstein philosophy which went willy-nilly with formal constructions and basically managed to ignore PI entirely (or otherwise remain mum about it) as well as the his remarks on the foundations of mathematics which set up a lot of problematic for the later.

> but certainly not in the sense of providing a positive result or foundation for one

I don't think philosophy strives to provide positive results. That is left to science. But philosophical ideas can help direct science, and that is a great contribution.

> post Frege philosophy

Post Frege? Even if you only value analytic philosophers, and mostly for their contributions to mathematical logic, I think you should at least acknowledge Russel, Kripke, Putnam and possibly others, if only for their immense contributions to computer science.

Let's not forget Quine.

> in it's essence philosophy is about how you approach and solve problems, and more importantly how you think about them

This. This is what helps.

> how you think any post Frege philosophy helps

If it doesn't then that explains precisely why we need more new philosophy to make the breakthrough.

Physics can never be about a specific philosophy until it works. Without a working philosophy, we're stuck, which is pretty much where we are right now. We need to keep thinking, and we are, so it's really only a matter of time.

If you really dig into what they're talking about, it presents potential avenues for "solutions" to issues from why physical laws are what they are to how consciousness and free will would be possible. It's a lot more than just angels-on-head-of-pin stuff, and goes far beyond Smolin's previous critiques of string theory.

If a philosophy is making positive statements it's an obvious sham - the best you can do with a meta logic is define the limits of what can be expressed within a logic (postive and negative as related to this world) it cannot have anything to do with producing results.

But it can. Philosophy can clear the brush between two competing paths. If we take path A, that leads to X, Y, Z, whereas if we take path B, that leads to J, K, L. Philosophy has done nothing to say whether reality is more A-like, or more B-like, but in delineating and making clear the consequences of an A-like world vs a B-like world, it has done a significant service in producing physical results. When experimentalists show an inkling of a tiny sliver of 'K', we know can collapse with logical certainty around the B-like world.

Trudging down those paths prior to experimental evidence is of very real value and is not disconnected from the physics itself.

Philosophy is not correctly defined as the generation of logic. If the philosophy you learned is defined in connection with logic then it can be term deteriorated philosophy. The proof is that if we had learned philosophy correctly we also form our own eye of wisdom to see what is in the truth but no one can verify what is true through logic alone as you cannot verify your axioms without external referents. The reason is that truths can only be verified through problems. This all means we can't see the world through thinking, but through the problems.

If anyone post-Frege can define the term philosophy correctly, then it will be helpful to physicists. If not, then not.

It's impossible for someone to teach something that they don't know, have never learned, or learned from someone who doesn't really know.

Why does a precise definition of the discipline matter? AFAIK, there is no such definition of what constitutes physics or even mathematics. Those disciplines are usually "defined" by whatever it is that the people associated with them choose to study. Physics is as physicist does; philosophy is as philosoper does.

Good question. It shows that this is the snit we've gotten ourselves into: philosophy=formal systems. Physics must be based on a formal system, therefore we must have an advancement in formal systems to help physics. There is no advancement, yadda yadda.

The "good" parts of philosophy are the mushy parts. And when you've created a formal system that's self-consistent yet offers no value, you're going to have to step outside formal systems for a while.

That's gotta be a painful leap for a lot of folks who believe that math is the ultimate reality.

I wouldn't equate philosophy with formal systems, philosophy is more about what a formal system is, what formalisms actually mean, and deciding when they are important tools for knowledge, and when they are not.

I'm a regular here and genuinely confused as to why this post was downvoted. What am I missing?

>The bleeding edge of theoretical physics, especially in the past 60-70 years has really shifted towards almost the metaphysical regardless of how much elegant math there is behind it.

Which is a major problem, given the truism that theory is under-determined by experimental evidence! If given any simple theory of physics I can construct a more complicated theory that makes the same predictions, then we desperately need to confine ourselves to theories that do make unique predictions, lest we be generating ever-more-complicated versions of theories we already had.

That's like saying "we need to confine ourselves to business plans that make money." Everyone understands and agrees on the importance of this as an ultimate goal but nobody knows the path to get there -- the hard work is in trying and rejecting promising paths until you find one that works.

Right. So there's room for developing hypotheses that we don't yet know how to test. Because some branch might be testable, or some new technology might become available. Just as with business plans and profit. But at some point, someone should maybe call bullshit. Kuhn etc have explored criteria. One of them, as I recall, is asymptotically increasing complexity.

The focus hasn't been on developing more complicated theories, but instead on developing less complicated theories. This provides additional explanatory power, and provides a mental model in which we can ponder thought experiments that may yield further insights.

For instance, many-worlds is actually conceptually and formally simpler than Copenhagen.

I'm curious to know your opinion. Suppose an individual appeared who said they knew the reality of gravity and how to design an apparatus to verify it. How would s/he be treated?

The quantum gravity community alone has a whole plethora of competing, mutually contradicting theories even within subgroups like string theory. Well-known and respected physicists make their careers off of proposals like:

  - Two time dimensions [1]
  - Reality is actually a discrete, combinatorial graph [2]
  - We live in a Euclidean space virtual machine on a 
    general relativistic virtual machine on a Euclidean actual machine [3]
  - Reality is a souped up version of liquid helium, 
    and of course dark energy is just surface tension [4]

I took a bit of license with these descriptions, but when this stuff doesn't get you written off as a crackpot (as long as you've got an actually theory going on and can explain it to others), what will?

[1]: http://physics.usc.edu/~bars/twoTph.htm [2]: https://en.wikipedia.org/wiki/Loop_quantum_gravity [3]: https://en.wikipedia.org/wiki/Euclidean_quantum_gravity [4]: https://en.wikipedia.org/wiki/Superfluid_vacuum_theory

Outlandish but testable claims are treated well by the Physics community. Take the recent example of the EmDrive[1], which has gotten a few replication studies. Nothing conclusive yet, but it hasn't been dismissed out of hand by everyone.

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

Are you from the physics community? The EmDrive wasn't viewed well at all, it's viewed as completely baloney. None of the early experiments afaik was none with sufficient experimental rigor to reveal anything surprising. All this while making an absolutely huge claim. The average physicist (I'm not one) wouldn't want to waste any more time with it than with the 2nd-law-violating "free energy" claim of the week.

Getting replication experiments is "well" for a crackpot claim. Having the average physicist accept it would be a bit too much -- the point was that the claim was testable and thus not universally rejected.

You say they're treated well, but the EmDrive was specifically sponsored by NASA, which means you're not answering the same question as what I asked, but changing it by presupposing that I asked how such a person would be treated if they were already institutionally sponsored.

First, I can't possibly answer the question you asked, because you asked for the opinion of someone else. Second, if you had read into the second paragraph of the link, you would see that the EmDrive is not institutionally sponsored nor developed by NASA. Third, offering analogous evidence is not the same thing as changing the question.

Actually, it was institutionally sponsored, because the very work to peer review it was done by labs directly sponsored by NASA.

If the initial work were not peer reviewed, you would not be holding it up as an example of something successful.

Therefore, it's NASA's sponsorship of the peer review which is a necessary and direct cause of you calling it successful here.

So my initial assessment of what you said stands. You're saying the physics community is receptive because NASA sponsored an attempts to verify it. That proves nothing about the receptivity of the physics community nor of even NASA. But I don't expect this to be something you can easily agree with. After all, you're proving my point.

It isn't very clear what you think should happen here.

A fairly outlandish invention was developed outside the mainstream physics community. The community saw it and made the effort to test it. This is good, right?

If not, then what should happen?

> After all, you're proving my point.

Which is what exactly?

That you have gotten something really important really wrong which you are not yet able to be aware of.

Can you be more specific?

Of course I can. I have been. Now if you want to know something more specific, you need a more specific question which you can make by using things I've said.

EmDrive has not been "sponsored" by NASA. The researches at their Eagleworks labs built a prototype and tested it, but that's not quite the same thing.

Thanks for the backup. We lobsters gotta stick together!

Would we be here talking about the EmDrive as anything like a possible breakthrough which was well received if it were not for that NASA-sponsored work?

I think so. NASA has done relatively little with it so far.

It's not like they've given it their stamp of approval. Eagleworks is NASA, but as I understand it, they are on a pretty loose leash, and it's their business to investigate somewhat-crackpot ideas.

Bohmian mechanics is fundamentally incompatible with quantum field theory. QFT is the best theory we have today (standard model).

Why do you say that? There are adaptations that have creation and annihilation of particles in Bohmian mechanics: http://arxiv.org/abs/quant-ph/0303156

The main issue is that QFT does not generate a mathematically well-defined evolution of the wave function, but there are promising directions on that front as well: http://arxiv.org/abs/1506.00497

Basically, they treat the Hamiltonian as a whole instead of a perturbation and use a domain for it that has the probabilities flowing from one area to another appropriately to the different particle sectors.

There is also work on dealing with relativity which is a separate issue. While there are solutions, mainly centering on finding a natural foliation, the tension with relativity has not really been resolved, a tension which exists regardless of interpretation.

> While there are solutions, mainly centering on finding a natural foliation, the tension with relativity has not really been resolved, a tension which exists regardless of interpretation.

Exactly, John Bell had it right 50 years ago: non-locality is the problem of QM that needs to be solved, and other interpretations let you simply gloss over the problem without really addressing it. The recent work for finding a natural foliation present in any formalism with a wave function, including Bohmian mechanics, proves every QM shares this problem (or if you think one doesn't, then none of them do for the exact same reasons).

> This is Smolin, making his usual, and valid, criticisms of modern physics. Smolin's basic complaint is that there is no experimental evidence for string theory.

Uhmm, he’s working on quantum gravity too. Just a different approach. The same applies to loop quantum gravity.

> A practical implication is that it doesn't lead to any technology.

Who cares? It’s science not engineering.

> Smolin also doesn't like many-worlds, because it talks about unreachable regions. This he considers too speculative. There's a basic problem in quantum mechanics, which leads to Schroedinger's Cat, the Copenhagen Interpretation, and, in the end, many-worlds.

The string landscape [1] and the many-worlds interpretation [2] are two completely different things. The string landscape indicates that string theory may never be able to make any predictions. Some physicist try to use many universe in combination with the antropic principle to “solve” this problem. But I’m pretty sure this is a very small minority.

The many-worlds interpretation of quantum mechanics is just that, an interpretation. It doesn’t make any measurable difference from any other interpretation. And the Copenhagen interpretation doesn’t lead to many-worlds, they are just two different interpretations of the same theory.

> Physics has been stuck on this problem for almost a century now.

At this time I wouldn’t call it a “problem” of physics. If all predictions are the same it’s just a matter of taste which interpretation you prefer. To bring it into the realm of physics you would need to come up with some kind of theory of the measurement process that actually makes testable predictions.

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

[2] https://en.wikipedia.org/wiki/Many-worlds_interpretation

It's not a matter of taste. Philosophy is about which questions you ask.

More specifically, it's about what kind of questions are considered worth asking. You can track the changes through history, and philosophy often leads politics and art as much as it does science.

Philosophy looks like the most abstract and possibly trivial pastime, but in fact it's incredibly powerful and influential, because it literally makes some world views thinkable and others unthinkable.

The different interpretations of QM are trying to ask different questions about reality. The fact that they're empirically indistinguishable suggests that either they're literally irrelevant - because they all give the same answer - or that no one knows how to ask a more insightful question yet.

If a more insightful question exists, it may come from some completely unexpected direction.

Physics has had a century to think about the problem, and hasn't gotten any closer to a definitive solution.

That suggests either more time is needed and we just haven't got there yet. Or perhaps the real explanation is literally unthinkable within the world view we have today.

> Uhmm, he’s working on quantum gravity too. Just a different approach. The same applies to loop quantum gravity.

String theory isn't a quantum theory of gravity in the same way that loop quantum gravity (LQG) is, LQG is background independent. String theory assumes there is a flat background spacetime already present and perturbatively builds off of that. LQG doesn't make this assumption and tries to create spacetime from scratch.

LQG did make some testable predictions, as has string theory in recent years. One was regarding the smallest units of area and volume that might have been seen in light scattering in cosmic ray or gamma-ray burst experiments[1]. Another suggesting evaporating black holes could be used to probe LQG [2]. String theory proposed supersymmetry, where each fundamental particle had a supersymmetric partner. Electron => selectron, quark => squark, etc. But none of these proposals have panned out as yet. Thus far supersymmetry has not been found and LQG has not been able to recover general relativity in a classical limit.

> The many-worlds interpretation of quantum mechanics is just that, an interpretation. It doesn’t make any measurable difference from any other interpretation.

In the last couple years, many-worlds researchers have come up with some potentially measurable consequences [3].

[1] https://www.edge.org/conversation/lee_smolin-loop-quantum-gr...

[2] http://dx.doi.org/10.1103/PhysRevLett.107.251301

[3] http://journals.aps.org/prx/abstract/10.1103/PhysRevX.4.0410...

Just reading the abstract to [3], I do not see any claims that they have tested any unique predictions of many worlds. Rather they have used this model to recover some known results.

It's not science without an experiment.

> Physics has been stuck on this problem for almost a century now. Philosophy won't help.

It sure seems to be an epistemology problem which puts it squarely in the realm of philosophy, not physics.

Yeah, many of the 'popular' discussions of Quantum Mechanics that show up here on HN do often diverge well into philosophical directions and away from hard science.

It's true that science and philosophy did come from a common discipline (my undergrad uni originally had a Natural Philosophy dept that only became a physics department somewhere between 100-150 yrs ago).

Though I thought one of the physics professors when I was in grad school said it best : "Physics is philosophy with integrals".

I agree but I think there are important philosophic[1] questions raised by quantum mechanics and, to a lesser extent, special relativity. One hundred years ago the founders of the new physics had the same questions but could not resolve them to everyone's satisfaction. One of the founders of modern physics (I forget who) said (I am paraphrasing) that all the different views on the "meaning" of the new physics amounted to where you want to hide the contradictions. The Copenhagen "interpretation" was not a definitive win but a truce.

These brilliant men argued for a decade and could not resolve it so they decided to bury the questions. It was not unreasonable in that context to accept that they did not know the answers but the theories work so let's use it and see where it leads. I am sure the hope was that the answers to the philosophic questions would become clear as our understanding of the new physics grew. There was a lot of work to do aside from the philosophic questions. Fast forward 100 years and here we are, the philosophic questions are still unanswered, and the Copenhagen interpretation has hardened into dogma banning any discussion of fundamental questions in physics. I have respect for Smolin for at least trying to re-raise these important questions.

[1] I am of the view that philosophy is distinct from physics in that it studies the nature of reality and knowledge, thus it applies to ALL fields not just physics. WHAT do we know and HOW we know is the more (or the most) fundamental science. The physicists are throwing out the baby with the bath water when they reject philosophy en masse instead of rejecting bad philosophy.

I like your quote at the end so much that I tried to find a stronger citation for it. The only thing I could come up with was a 12 year old comment of yours from Slashdot: https://science.slashdot.org/comments.pl?sid=115306&cid=9766... :)

Haha, thanks for that blast from the past!

The quote was by Zlatko Tesanovic, a brilliant and witty theorist who sadly passed away a few years ago. Here's a link to a page of some of his other quotes, as recorded by his students. IIRC he said the integrals quote when I was the TA for his statistical mechanics and thermodynamics class.

http://blog.danallan.com/notes/2012/parting-shots/

thank you for the link, and I'm sorry to hear of his passing.

"Physics is philosophy with integrals." -- Well, too bad for physics... But where to look for guidance? Philosophy tries to answer questions that do not have answers; theology studies that which does not exist. What a waste of time. Even Einstein, how many years did he spend trying to understand the meaning of these philosophical "integrals", to no avail? Even his mind was powerless trying to come up with an interpretation of the quantum mechanical theory that would make sense. Should we accept this as an indication that there are limits to our ability to understand, just as there are limits to what we can achieve physically?

"Should we accept this as an indication that there are limits to our ability to understand, just as there are limits to what we can achieve physically?"

That's a quintessential philosophical question.

> What a waste of time.

A philosophical assertion about what should be valued, if ever there was one.

World-over, the degree conferred for significant contribution through original work in Science (and Engineering) has principally been Doctor of Philosophy. I doubt if it will ever change.

I love that quote.

  > It sure seems to be an epistemology problem which puts it
  > squarely in the realm of philosophy, not physics.

It's absolutely a physical issue, not a purely philosophical one. Under the Copenhagen interpretation, the probability densities which drop out of Quantum Mechanics reflect some sort of objective physical reality, as in Schroedinger's Cat. The alternative to this is the so-called "hidden variables" theories [1], which posit that those densities reflect variability in some kind of hidden extra state in quantum-mechanical systems of which we are currently ignorant. The very real Bell's inequality experiments [2] are an example of the physical quality of this dichotomy.

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

[2] https://en.wikipedia.org/wiki/Bell_test_experiments

Maybe, but sadly philosophy doesn't have a good track record when it comes to actually solving problems.

It may be that my memory does not serve me well, but I think I got an impression from the history of the philosophy that once there is a field of philosophy that actually starts solving problems, it very fast changes its name to something else than philosophy. For example[1], Newton's 1687 Mathematical Principles of Natural Philosophy later became classified as a book of physics.

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

That's my thinking too. When trying to define what philosophy is, I have settled on this: Philosophy is the reasoning about poorly defined things, using similarly fuzzy steps. This is not a value judgement.

Once we get a better grip on an area, then, finding more proper definitions for its concepts, we branch it off as a subject of its own.

And there. You are doing philosophy.

Yes, I would say so.

It seems more like the usage of the word 'philosophy' has gradually shifted to mean something very narrow, when at times it could have been used as a synonym for 'science'.

My favorite definition: Philosophy is the practice of looking into questions without clear-cut answers.

Philosophers disagree a lot in their specific definitions, but most definitions assume it is the study of the broadest and most general questions, like what is truth, what is reality, what is the good, and so on.

Also, any particular field you study has philosophical assumptions, like about the reliability of sense data. The reason modern science is so fabulously successful is the philosophers who established it got rid of the supernaturalist assumptions of previous science, and added the assumption that reality is mathematically describable.

What Smolin and Unger are saying is that the particular philosophical assumptions behind string theory and a lot of related physics are mistaken. This would seem to be at least possible.

> Philosophy is the practice of looking into questions without clear-cut answers.

Indeed, or the practice of asking questions about the nature of questions, ie. what questions are meaningful, well-formed, yield knowledge, etc. in any given subject.

When you understand the nature of the questions in a particular subject, then you're no longer practicing philosophy, you're gathering knowledge of that subject, ie. math, physics, chemistry, etc.

Indeed, see PhD

So basically philosophy as an incubator for new scientific field startups? I like that notion.

Yeah, I like it too :-) Philosophy has surely delivered unicorns: Mathematics, Physics, Biology, Chemistry, Computer Science! The question is, can Philosophy deliver another one?

Economics too! i.e. the "worldly philosophers".

You mean the field famous for predicting six of the last five recessions?

You mean the field that predicted the last 80 of 8 recessions.

Yes, while mostly also referring to the period immediately prior to the Global Financial Crisis as the "Great Moderation".

But they don't even have the .com domain...

That was profoundly disheartening.

That happened just once, though (as far as I know). "Natural philosophy" was a catch-all term for anything that involved the study of nature, before everything was formalized into categories such as physics and biology, and we decided "science" was a better, snappier term for it.

The word "scientist" was only invented in 1834. The scientist who coined it, William Whewell, also thought up "phycisist" and a whole bunch of other modern terms. [1] Interestingly enough, "naturalist" still survives as a legit term, as does "natural history".

[1] http://etymonline.com/index.php?allowed_in_frame=0&search=Wh...

There's an interesting back and forth with Boltzmann and Mach that touches on this:

> Boltzmann's kinetic theory of gases seemed to presuppose the reality of atoms and molecules, but almost all German philosophers and many scientists like Ernst Mach and the physical chemist Wilhelm Ostwald disbelieved their existence. During the 1890s Boltzmann attempted to formulate a compromise position which would allow both atomists and anti-atomists to do physics without arguing over atoms. His solution was to use Hertz's theory that atoms were Bilder, that is, models or pictures. Atomists could think the pictures were the real atoms while the anti-atomists could think of the pictures as representing a useful but unreal model, but this did not fully satisfy either group. Furthermore, Ostwald and many defenders of "pure thermodynamics" were trying hard to refute the kinetic theory of gases and statistical mechanics because of Boltzmann's assumptions about atoms and molecules and especially statistical interpretation of the second law of thermodynamics.

> Around the turn of the century, Boltzmann's science was being threatened by another philosophical objection. Some physicists, including Mach's student, Gustav Jaumann, interpreted Hertz to mean that all electromagnetic behavior is continuous, as if there were no atoms and molecules, and likewise as if all physical behavior were ultimately electromagnetic. This movement around 1900 deeply depressed Boltzmann since it could mean the end of his kinetic theory and statistical interpretation of the second law of thermodynamics.

> After Mach's resignation in Vienna in 1901, Boltzmann returned there and decided to become a philosopher himself to refute philosophical objections to his physics, but he soon became discouraged again. In 1904 at a physics conference in St. Louis most physicists seemed to reject atoms and he was not even invited to the physics section. Rather, he was stuck in a section called "applied mathematics", he violently attacked philosophy, especially on allegedly Darwinian grounds but actually in terms of Lamarck's theory of the inheritance of acquired characteristics that people inherited bad philosophy from the past and that it was hard for scientists to overcome such inheritance.

> In 1905 Boltzmann corresponded extensively with the Austro-German philosopher Franz Brentano with the hope of gaining a better mastery of philosophy, apparently, so that he could better refute its relevancy in science, but he became discouraged about this approach as well.

https://en.wikipedia.org/wiki/Ludwig_Boltzmann#Philosophy

> The reason Aristotle didn't get anywhere in the Metaphysics was partly that he set off with contradictory aims: to explore the most abstract ideas, guided by the assumption that they were useless. He was like an explorer looking for a territory to the north of him, starting with the assumption that it was located to the south.

> And since his work became the map used by generations of future explorers, he sent them off in the wrong direction as well.

http://paulgraham.com/philosophy.html

I have a lot of respect for PG, but boy, is he off track on that.

Aristotle was highly specific and highly empirical. His ethics, for instance, is an elaborate study of the various ways individual go right or wrong in their decisions. His politics was based on extensive studies of the constitutions and political histories of nearly a hundred Greek states. And of course there was his biology, based on empirical studies of over a hundred different animal species.

And as for his physics, according to this astounding article by Carlo Rovelli (yes, that Carlo Rovelli), his physics is accurate for the phenomena he was studying. Rovelli even converts his ideas into equations.

https://arxiv.org/pdf/1312.4057v2.pdf

> For example[1], Newton's 1687 Mathematical Principles of Natural Philosophy later became classified as a book of physics.

That is a good example. I was trying to think of others since then. That was 500 years ago or so. What are some more recent ones for physics?

I imagine if logic is considered part of philosophy, perhaps boolean and propositional logic had a hand in helping computing...

Then if ecology or sociology is considered I can see how philosophical ideas about class, society, environment would be incorporated into practical fields or be used to start societal transformations (Marxism perhaps?).

But I can't think much for physics recently? I have read and seen known physicists dable in and use philosphy to explain what they accomplished or observed. Bohr, for example, was fond of Kierkegaard. It would be good to have examples of philosophers who changed the course of physics.

It's surprisingly recent, but much of our modern understanding of what the scientific method is comes from Karl Popper:

https://en.wikipedia.org/wiki/History_of_scientific_method#P...

Except for being the origin of physics, astronomy, medicine and other fields? "Philosophy" is a wide spectrum of which only a very small part is concerned with problems so abstract that we cannot expect a solution to them.

Exactly, when philosophy actually started solving a problem it became another discipline.

So what's left in philosophy is the stuff that no one has gotten very far in solving in 3K years. Why is life worth living? What is a good life? What is the best beer?

Philosophy & beer:

http://www.youtube.com/watch?v=l9SqQNgDrgg

Only in the same way that a patent troll invented using cookies to keep a shopping cart. Philosophy expounded enough ideas both good and terrible that they where the first ones to say X. However, plenty of scociety's who never heard of X did the same thing. If anything science is the antithesis of philosophy as it does not care about abstractions only observations.

Philosophy is the epitome of scientific navel-gazing. Don't get me wrong, gazing at one's navel is an important thing to do – sometimes – but this continual attempt to backwards-justify all sciences as flowing out of philosophy are overblown.

Astronomy and medicine are two very obvious examples. Primitive cultures didn't need philosophical underpinnings to notice and record the patterns in the sky or to figure out which plants helped with fevers or how to set broken bones. Philosophy might have helped science in places with structural issues, but it's reaching too far to say that nothing would be around without philosophy.

And calling philosophy navel-gazing is navel-gazing.

The philosophy of information is a great example of where it's incredibly important [1]. I seriously, seriously doubt that information theory would have come about without many of the philosophical underpinnings that came before it. It's not just about structure.

[1] http://plato.stanford.edu/entries/information/

edit: interestingly enough, some of the posts in your blog would be considered "philosophy". ;)

I would suggest you study more non western history. People did a lot of what we think of as science and math with very different underpinnings. Without a basis for comparison you can't separate what is actually important from an accident of history.

PS: The two most widely used and useful parts of math where completely unknown to the anchent Greeks. Aribic numerals are the first example of useful information theory after writing.

I understand what you mean, but calling it an accident of history is a pretty strong minimization of what amounts to applied philosophy towards genuine innovation.

When I talk about information theory, I'm talking more about the more generalized forms of it (Shannon, etc), not necessarily something that could generally be described as 'information' in a more classical definition. Specifically, https://en.wikipedia.org/wiki/A_Mathematical_Theory_of_Commu....

(this is a subject I'm actively learning over time, so please correct me if I'm wrong!)

If you consider morse code was 100 years old at that point, there had already been a lot of very practical work under that heading. With earlier effort focused on designing and cracking encryption systems.

Shannon was more an outgrowth of having already abstracted information and looking for ways to encode that for transmission. I don't want to downplay the value, but in historical context it's very different from how you learn about such things after the fact.

Fair enough - I completely agree.

> And calling philosophy navel-gazing is navel-gazing.

It is, and as I said sometimes doing that is _good_ despite the derogatory connotations of calling it as such.

There's a point I'm trying to make which is not coming across, and I'm not sure I'll be able to.

Computer science is really just applied philosophy.

Most of Computer Science isn't science in the sense meant by describing physics as a science. Most of what is science in computing is simply applied physics and applied mathematics.

That doesn't make it any less worthy of study of course.

This reminds me of the old adage about the drunk looking for his keys under the lamp post because "that's where the light is". If the solution in physics requires a revolution in philosophy then that is where we must look.

But it might help identify what the problems to solve actually are. What are we seeking, what are we trying to explain?

"How we go about robust scientific methodology" is a problem solved by philosophy.

Maybe because much of what started as the goals and methods of "philosophy" were later appropriated and redefined as "science"?

They are both human endeavors to better get at and understand the truth about ourselves, the universe, reality, etc. Philosophy often extends further into realms such as art, morality & ethics, dignity, aesthetics, the role of society, and human nature. Philosophy even takes a meta-view of science, asking how we are justified to even claim to know something to be true at all (epistemology). And for the most part, these questions are answered in terms of and in concert with our scientific understanding.

Moreover, evidence-based science itself is to some degree an outgrowth of Descartes' "method of doubt" and rationalism, then the empiricist philosophical movement, and on and on. It's no wonder that throughout history often the leading scientists/mathematicians and the leading philosophers were the same people.

Concepts such as natural rights, liberty, free will, social justice, etc. all originated in philosophical works, and have indeed "solved problems" by influencing people who are say, in the process of forming secular governments after a political revolution. You can draw a fairly straight line from Plato to Descartes to Hobbes to Locke to the Constitution. When we talk about a "bill of rights" -- where is this concept of a natural human "right" even from? Philosophical theories such as utilitarianism, the meaning of good vs. evil, are used every day in our legal system, economics, politics, and foreign policy.

Moreover, often a breakthrough in science or development in society may have very practical consequences which FORCE people to face unavoidable philosophical questions. Should scientists be legally permitted to clone humans? Should a Tesla kill its own driver to avoid plowing through kids crossing the street? Should there be a minimum wage? Should pharmaceutical companies make life-saving drugs free? When should abortion or infanticide be permitted?

These questions must be answered reasonably-- I'd much rather have them discussed through the lens of rational philosophical discussion rather than religious or purely emotional "go with the gut".

So philosophy has served as an on-ramp to science. But among its benefits, it also helps us move from the descriptive study of the universe to the prescriptive-- to paraphrase the great philosopher Dr. Ian Malcolm-- there's a benefit to moving from the scientific question of if we could to consider the philosophical one of if we should.

Just like there's a "God of the gap"-- a notion that a need for God pushed back as our scientific knowledge expands, so it seems there is a "philosophy of the gap"-- some people seem to redefine "philosophy" to mean useless mental spaghetti that goes nowhere. Do you judge science by the same criteria? Does every "failed" experiment constitute a failure of science?

Given its usefulness, especially as an alternative to religious methods where "science" doesn't offer a clear answer about how people and societies "should" behave, I think damning philosophy too hard is kind of unfair.

Bullshit. How do you think your computer functions? You don't get high level programming languages without philosophy. Where do you think natural sciences came from?

>Where do you think natural sciences came from?

Alchemy. But that's no reason to still respect alchemists.

Alchemy is a good example. Alchemists dabbled in chemisty but they also took for granted that chemistry has deep symbolic and semantic meaning. Figure it out and chemistry will crack.

It turned out to not be the case, time after time.

There's no inherent meaning in how substances interact. There are laws, they're consistent but devoid of any meaning, on human level.

That's why I'm deeply scetical towards any New Age-style ideas.

The body of results from alchemy resulted in the narrow, useful part of it becoming formalized as chemistry. The body of results from string theory (or many worlds interpretations) is non-existent.

How long was alchemy a serious field of study? Thousands of years, right? String theory is 75 years old.

I still respect Isaac Newton, even tho he was an Alchemist and searched for Atlantis... https://en.wikipedia.org/wiki/Isaac_Newton%27s_occult_studie...

If you understand alchemy you have all the reasons to respect them

I think of philosophers as basically being 1000 Shakespearean monkeys. The world would be better served by 1000 scientists.

What are we talking about with "philosophy"? And what is "physics"? Are physicists featureless spheres unable to be "philosophers"? https://www.edge.org/conversation/a-philosophy-of-physics

What "philosophers" are we talking about here? Lakatos? Chomsky? Newton? Logicians? Or do we have some composite postmodern blowhard in mind? (Like any industry's products, philosophy's product quality varies with factors like producer. So specifics are important.)

There's a bias in physics culture against philosophy. (It's no doubt elsewhere too, but very apparent in physics.) But fortunately, there's many exceptions who like to take a step back and think about what they're doing.

Peeling back a level, science is a belief system based on observations. What is a valid observation - if I say I saw it once that is not valid, if I say look in this place or way and you can see it too, well, that is. But what if I say "look in this place and way and you will see this kind of thing once out of a billion trials, and all the other things that are seen are not real"? Science admits that view, and I would not disagree but I am aware that this is a choice - a philosophical view that I have adopted as part of the assumptions that I make to use the belief system that we currently call science. This system is different from the versions of science that were in use 100 years ago, and is changing now with the rejection of intervalism (p=0.05). So bring in 1000 scientists and let them do some philosophy, because to do anything that's what they have to do.

Science is not a belief system, it's a method of verifying beliefs and turning them into knowledge.

Is the practice of science fixed? Do scientists use, unwaveringly, the methods of their predecessors? Why do the methods and practices of science vary over time?

I fail to see the relevance of any of your questions to the topic at hand, so rather than playing the Socratic method, how about you just lay out your argument.

Methods vary in philosophy, in science they improve.

I can hear the pattering of tiny feet on the heads of pins....

Not if the scientists are working on string theory. I'd rather have philosophers 100:1 in that case.

Thank you for explaining your philosophy of science.

Shorter version with nothing lost: "Thank you for explaining your science."

> The world would be better served by 1000 scientists.

Why?

"The world would be better served" carries a lot of cultural baggage.

> It sure seems to be an epistemology problem which puts it squarely in the realm of philosophy, not physics.

Sounds like a good idea and would like to see, for example, a philosophy professor from some university one day publish a paper in arxiv and turn the world of physics upside down with it. It would be like "... because of these logical inconsistencies ... x, y, z quantum mechanics is actually governed by hidden variables, q.e.d"

I just don't see it in practice though. I think it only seems as if philosophy is deeply entwined with and ready to be exploited to help physics, but it is only because physicists were marginally interested in it and offered some philosophical explanations after the equations and experiments have been proven. I think most of those were mostly for curiosity's sake and were rather secondary to their main achievements.

> It would be like "... because of these logical inconsistencies ... x, y, z quantum mechanics is actually governed by hidden variables, q.e.d"

They already do this. Many philosophers of science pursue realist interpretations of QM though, like de Broglie-Bohm, and so they aren't published very widely. The measurement problem is the serious stumbling block for anti-realist interpretations, and why many such philosophers are realists. The measurement problem just doesn't trouble practicing physicists.

You have to be very careful about which multiverse theory you refer to. There is a Many-worlds interpretation of quantum mechanics which don't lead to any different physics. It's fundamentally untestable and doesn't matter. So far you can't derive new measurable consequences (to my knowledge) of this, and there's no physics that really hinges on it. If you don't like this interpretation, you can pick some other one until you're happy and shut up and calculate with the schroedinger or dirac equation which has been verified stupidly well with experiment.

Multiverse theories in general may say that the universes interact. They may have differing coupling constants. You know you might try to come up with some new physics but your new physics hinges on these things existing... and that's fine... that's how new things are discovered, but we're at a point where SUSY is taken as a given and multiverses are taken as a given and theorists have this really much more convenient model of the universe that they're starting from and making unmeasurable conclusions and it just seems so removed from reality! That's the issue.

> Smolin's basic complaint is that there is no experimental evidence for string theory.

The issue wasn't that there was no evidence but that there weren't any predictions that would be testable in our lifetimes.

Superstring theory did make a testable prediction though: Supersymmetry. But the LHC didn't find any evidence. [1]

[1] http://arstechnica.com/science/2015/12/first-high-energy-lhc...

Modern academic philosophy won't help because it's dominated by certain false ideas.

The problem with physics today is rationalism - constructing theories with only partial reference to experimental data. Some fields, like psychology, have the opposite problem - empiricism - where they accumulate countless statistical correlations but fail to integrate them into consistent theories.

I suggest anyone who's seriously interested in a solution to these issues to listen to the following, then look up Leonard Peikoff and David Harriman's other writings on the subject.

https://campus.aynrand.org/campus-courses/understanding-obje...

> The problem with physics today is rationalism - constructing theories with only partial reference to experimental data. Some fields, like psychology, have the opposite problem - empiricism - where they accumulate countless statistical correlations but fail to integrate them into consistent theories.

"Rationalism" is still serving us very well in pretty much every other field of physics except unification theories. We're still coming up with great new theoretical models based on working with the laws we have, sometimes driven by the need to explain existing experimental results and sometimes to look for new places to do fruitful experiments. There's a much better balance between the two for physics as a whole than you're making it out to be.

I'm not sure how wrapping in Ayn Rand's theories with all their politics is going to streamline physics.

I think then, that by IsaacL's definition, those other parts of physics where theory and experiment are well balanced don't suffer from (excess) "rationalism", which he seems to define as a reliance on theory without experiment.

> Modern academic philosophy won't help because it's dominated by certain false ideas.

Care to tell us what they are?

Check out his URL's domain name, then make the usual assumptions.

> make the usual assumptions

I have no idea what this is supposed to mean or imply in this context, but it seems to be a classic HN response asking people to judge a book by it's cover instead of its contents/arguments, which is even less helpful.

Objectivism is basically built on a bunch of strange axioms, and to a large part completely denies that they're arbitrarily chosen axioms instead of hard facts. They treat logic built on other axioms as inherently wrong.

The nice thing about a book cover is that it tells you which book is inside, saving you the trouble of having to read it every time.

It's sometimes reasonable to judge books by their covers.

I'm offering the opportunity to try to convert me to objectivism. :-)

It's hard to summarise. Read "Introduction to Objectivist Epistemology" which contains the fundamentals of a theory of knowledge, specifically a theory of the nature of concepts. That's the part which is relevant for this discussion and is also the foundation for everything else.

Ultimately you have to read Rand rather than read about her, as so many of her critics enjoy a somewhat loose relationship with reality. For example, the comment in this thread about "randian evangelism" on HN. I've encountered two other Objectivists on HN, whereas every week we have multiple hundred-comment threads on how fantastic an idea universal basic income is. That's pretty ineffective evangelism.

There's enough randian evangelism on this forum without inviting more.

Interesting. I suppose I haven't been here enough to see it.

Would like to read the book to know more. While the criticisms of "we're wrong headed to try this" might be valid, I don't know if anyone really has a better idea of what would be the "right headed" direction to go in.

If string theory shows 10^500 possible universes, then what if tomorrow we come up with a way to identify which universe we're in? Would we still discard string theory just because it wasn't developed with an empirical footing and start over, or would we begin to examine its other consequences?

That string theory is pretty much just a theory at this point is, I think, not a strong enough argument to not pursue its mathematics. Especially since the theoretical effort has apparently yielded interesting mathematical tools for other areas. If that contribution is discounted, then it pretty much becomes an argument about funding.

Secondly, I'm not sure why time needs to be any less 'real' if it happens to be emergent. The expression "it all adds up to normality" has some power to it. If you think about our current notion of time which holds that a photon crosses all points along its path "at the same time", but that isn't true of the electron or proton, what could we even mean by "time is real"?

I think philosophy can definitely help here. One philosophical answer to this problem is that physics or the physical world are just an ideas / models in our minds (I think it's obviously true but most people disagree). As long as a model is consistent with our perceptions (experiments), it's correct (correct up to this moment).

That's basically the whole point of the scientific method and that's how it evolved during the Renaissance when we went from philosophers and logic to scientists and experimental data. Few scientists have the delusion that our theories are anything but crude aproximations of the real world, each requiring extensive caveats and each with its own domain, outside of which they're useless (i.e. Newtonian mechanics is useless for high velocities and relativity is useless at the quantum level).

In my opinion Copenhagen is just as much philosophy as many-worlds, but I think many-worlds is at least more elegant.

But macroscopic decoherence (and therefore many worlds) is straightforwardly predicted by the Schrodinger equation. How is this philosophy?

Only one world of many is experimentally verifiable.

The problem is that we need a convincing mechanism to explain how the irreversibility implied by the Copenhagen interpretation arises, which to my knowledge no one has come up with yet.

What we understand so far is:

* the measurement process can be described as an entanglement of a quantum system with a large external system, followed by a dephasing of the wave function that is caused by the huge number of degrees of freedom in the external system.

* this dephasing decouples the individual terms of the wave function of the system that is being measured, thereby effectively suppressing any further quantum effects in those measured states. This is what we call a transition from a quantum state to a "classical" state.

* the measurement process itself is not a discrete event: We can perform continuous weak measurements on a system's state, which will only partially collapse the wave function (there have been many experiments done on this e.g. by Serge Haroche's group and more recently with superconducting systems as well).

* this whole process is completely reversible and can be described by the Schrödinger equation.

Now, if we want to introduce irreversibility into this picture (which is required for the Copenhagen interpretation), we need a mechanism for it to arise. To my knowledge, no one has come up with a good theory for this, as it would require to modify the Schrödinger equation in a way that subtly depends on the characteristics of the system being measured and the measurement system. This mechanism would need to contain a variable A that would account for the size of the measurement system, as we need to preserve reversibility when the measurement system is small (i.e. has a small number of degrees of freedom), while destroying it when the measurement system is macroscopic.

I'm honestly a bit surprised that no one makes this argument in favor of the many-worlds interpretation of quantum mechanics, as it's the only theory which accounts for all experimental evidence while not forcing us to invent a mechanism that "eliminates" the many realities that we don't want to accept, while in fact they arise naturally out of the theory. I think that many people just don't want to accept that the universe could work this way, even if it's the simplest and most straightforward explanation.

> I'm honestly a bit surprised that no one makes this argument in favor of the many-worlds interpretation of quantum mechanics, as it's the only theory which accounts for all experimental evidence while not forcing us to invent a mechanism that "eliminates" the many realities that we don't want to accept, while in fact they arise naturally out of the theory.

I think you're projecting the existence of these worlds. Certainly you could view the equations that way, or you could view the particles as fundamentally real and obeying a non-classical law of motion, as in de Broglie-Bohm, which was actually the first the interpretation to correctly account for measurement.

Math is not reality, sometimes it happens to describe reality, sometimes it doesn't, that makes math useful in doing science, but math is not science unless experimentally verified.

You can't say that the Schrodinger equation hasn't been experimentally verified. The problem is that we can only practically test it on microscopic objects, which means that people can introduce ad hoc mechanisms like waveform collapse to say it doesn't apply for macroscopic objects.

That's a very odd way of going about things. We can't actually observe galaxies over long enough timescales to be sure that gravity applies to them but their appearance is consistent with the existence of gravity so we don't even both to consider the possibility that there might be some separate force causing them to look that way.

> You can't say that the Schrodinger equation hasn't been experimentally verified.

I didn't. I said math doesn't always predict reality, sometimes it's just interesting math. Some maths are also physics, some maths are just maths and have no bearing on physics.

> Math is not reality, sometimes it happens to describe reality, sometimes it doesn't

Conjecture. It seems self-evident that our reality reflects the structure of basic discrete mathematics, ie. if there are two apples, eating one leaves 1 apple. No amount of rationalization will refute this fact. The fact is, the basic structure of our world is mathematical in some way.

It's not conjecture, it's a fact; you're describing a case where it does match reality, that doesn't contradict what I said. There are plenty of maths that are self consistent but don't match anything in reality. Just because someone can come up with some self consistent math doesn't mean that math predicts anything in the real world. To further clarify

> The fact is, the basic structure of our world is mathematical in some way.

Yes, but that doesn't imply the inverse, that all maths are reflections of reality. Reality can be described by maths, but not all maths describe reality. Or to further simplify, physics is the subset of maths that describe reality, which necessarily implies that not all maths do.

It is conjecture, because the most parsimonious position is a form of Platonism, of which the mathematics describing our world is but one structure in the mathematical universe.

Even if you wanted to subscribe to some form of mathematical naturalism, that still doesn't support your point that math that doesn't appear to have a natural analogue, doesn't physically exist. We thought this of many prior mathematical abstractions, like complex numbers and non-euclidean geometry, and they are both now indispendensible tools for describing reality as we know it.

You didn't address a single point I made, repeating yourself is not a valid form of argument. You are effectively claiming that all maths are physics, if you don't see the absurdity of that claim, which you continue to ignore, I can't help you. Beyond that, you're arguing with a stawman

> hat still doesn't support your point that math that doesn't appear to have a natural analogue,

I never made that point, and if you think I have, you've failed to understand the point actually being made.

What is the physical analog of the square root of -1? If all math is physics, then what physics does that predict? Maths are a language invented by humans, some of those language describe physics, some don't, that's not a conjecture, that's a fact.

> You didn't address a single point I made, repeating yourself is not a valid form of argument.

You didn't make any points, you merely repeated the dogma that there exist maths that have no physical analogue, which I already addressed in my first post. I merely provided more context on the philosophy of mathematics so you can read up on why your position is problematic at best.

> You are effectively claiming that all maths are physics

No I didn't. I pointed out the least problematic and most accepted position on that question, which refutes your claim that your position on mathematics is obviously the only valid position.

Your question about the sqrt(-1) is perfectly exemplary of the elementary misunderstanding of what your position entails. Abstractions don't exist a vacuum. I can just as easily ask you of the physical analogue of the number 1.

It's a meaningless question. Mathematics is an abstraction describing structure, and many things share the structure of the number 1. The structure of the sqrt(-1) appears in many places, like in wave mechanics.

The fact that you conflate maths with the particular syntax we use is another elementary misunderstanding. A grammar also has a structure, and we use that to represent the structure of mathematical objects, but math is not about syntax.

Finally, on the matter of absurdity, I suggest you reread my previous post. While you amazingly seem to think it's devoid of content, I can assure you that I point to two primary philosophies of mathematics, one which disagrees and one which sort of agrees with you, but still doesn't support your claims. It's up to you if you actually want to learn what mathematical truth is really about.

> > You are effectively claiming that all maths are physics

> No I didn't.

Great, then you agree with me, all math isn't physics, and there's nothing more to talk about.

Here's what you don't seem to grok.. from your own original rebuttal...

> The fact is, the basic structure of our world is mathematical in some way.

I agree, I've never once disagreed with that position, you simply failed to understand the point being made and that you're continuing to try and argue it is just... boring now.

> Great, then you agree with me, all math isn't physics, and there's nothing more to talk about.

No I don't. I'm disagreeing that your position is self-evident as you've claimed, and you've still failed to recognize that.

Oh I recognize it, that's called sarcasm, perhaps you've heard of it.

> Physics has been stuck on this problem for almost a century now. Philosophy won't help.

This "problem" is exactly a metaphysical one, so only philosophy can help. And there are plenty of interpretations that don't suffer from these problems too, like de Broglie-Bohm.

In a historical sense, things are only called philosophy until they become a science. Not so much in modern times, but certainly during the early years of philosophy.

Correct me if I'm wrong, but isn't the multiverse different than the many-worlds interpretation of QM? The multiverse talks about multiple big bangs and universes as bubbles.

Are the energies involved really unattainable? Can some sort of collider not reach them?

The Planck scale, where quantum gravity should have directly observable consequences, is ~10^18 GeV. The world's most powerful collider to date, the LHC, reaches a collision energy of ~10^4 GeV, not far from the theoretical maximum attainable by a ring of its size [1].

If you wanted to scale up the LHC by an energy factor 10^14, you would have to deal with the energy loss caused by synchrotron radiation (charged particles going around a ring are constantly accelerating, so constantly emitting electromagnetic radiation) which is ~E^4/R per turn [2]. To keep the same energy loss as at the LHC and pay an electricity bill which is only 10^14 times larger, you would therefore need to grow the radius R by a factor ~ 10^14^4 = 10^56.

The LHC radius is 4.5 km, so let's go with R = 10^56 km. That's 10^43 light years. For comparison, the radius of the observable universe is ~10^10 light years.

[1] http://www.physics.princeton.edu/~mcdonald/examples/lep.pdf

[2] https://arxiv.org/abs/1504.01627

[3] https://en.wikipedia.org/wiki/Observable_universe#Size

A linear collider would not be long enough. A circular collider would need either unattainable magnetic fields to curve the trajectories of the particles or itself have curvature that is small enough (i.e. have a radius similar to that of Earth's orbit around the Sun).

So yes, it is really unattainable.

Cosmic rays bombarding the atmosphere do attain such energies, but they are not controllable in a fashion that would permit most collider experiments.

All our manipulation of particle trajectories use electromagnetic forces.

If we were to be able to come up with the technology to manipulate the strong force, would that open up possibilities for alternative colliders?

One problem that I can see is that the strong force might be stronger (strength of 1 vs 1/137 of the electromagnetic force) but the acting range of the force is much smaller (diameter of a medium sized nucleus). The electromagnetic force has a far superior range (technically infinite, but the power drops off depending on the distance)

Arm chair physicist here... I would love your knowledge on the general idea.

Could something be built in space?

Theoretically, yes. If you set up billions (maybe even trillions) of powered electromagnets in a stable, very precise orbit around the sun and injected particles into the loop. However, this is hugely impractical and the sources of error would be huge. Electromagnet misalignments (with the error compounding over stellar distances), stray asteroids and comets, cosmic rays, etc would all effect the particle beam.

How much money are you willing to spend? ;-)

One way is to probe them indirectly. For example, string cosmology makes testable predictions (verifiable by observation, e.g. of the CMB). Conceivably, evidence could be found of something that happened in the early universe that is most easily explained within the string theory.

If memory serves, I believe a collider with a diameter the size of a galaxy would be needed to accurately test string theory. This isn't to say that we won't come up with some alternative method of producing high energies though.