Isn't this supposed to be a debate forum?

[jonjacson]

I asked about alternative formulations of quantum mechanics not using the Hilbert space and I got a mixture personal attacks and a blocked thread.

Is this normal?

I created this thread and got blocked:

https://www.physicsforums.com/threa...-hilbert-space-for-quantum-mechanics.1003389/

According to all the people who answered in that thread the Hilbert space is the only way to compute in quantum mechanics. It is like this Hilbert space is a religion.

Come on guys, I am sure you all know in Classical Mechanics you have Newton laws using forces and accelerations but you also have alternative formulations like the Euler Lagrange equations, or the Hamilton formulation.

Just in case you didn't know I copy and paste:

Hamiltonian mechanics is a mathematically sophisticated formulation of classical mechanics. Historically, it contributed to the formulation of statistical mechanics and quantum mechanics. Hamiltonian mechanics was first formulated by William Rowan Hamilton in 1833, starting from Lagrangian mechanics, a previous reformulation of classical mechanics introduced by Joseph Louis Lagrange in 1788. Like Lagrangian mechanics, Hamiltonian mechanics is equivalent to Newton's laws of motion in the framework of classical mechanics.

So it is possible to have several mathematical formulations of the very same discipline, that means my question was more than appropiate, or in other words, blocking that thread was innapropiate from my point of view.

Continue attacking people that makes proper questions and probably you will end up here alone.

 

[mcastillo356]

Don't get angry, please. I not know the context. I'm just trying to calm you down.

 

[Kolmo]

I was curious had you posted again. In my post on the thread I listed three other formalisms if you are interested. I think from the phrasing of your OP to others it sounded like you were trying to propose a new formalism.

 

[f95toli]

No, it is not primarily a debate forum.
The forums main goal is to teach people "established" physics, i.e. results available in textbooks or in articles published in scientific journals.
Sometimes there is of course disagreement when in comes to how to understand these results which can result in (long) discussions. However, I suspect this is not what you mean by "debate".

This forum is not a good place to discuss personal theories and/or ideas which can not be supported by results from the literature.

 

[Ibix]

To answer the question in your thread title: it is a discussion forum, not an unrestricted debate forum.

I'd say that what happened in that thread is that you defined the conversation as "a game" where "Hilbert space...[is] not allowed". Unfortunately that runs smack into a wall: any alternate formulation of QM is a Hilbert space in disguise, so disallowed by your formulation of the question, and any theory that is not equivalent to a Hilbert space is a non-mainstream theory, so disallowed by forum rules (unless you can provide a specific valid reference, which you didn't do). That will be why you got the responses you did and why the thread was closed.

What did you want to ask about with your thread? If you wanted to know about alternate formulations of QM, Kolmo listed a few. You could do some research and/or start a new thread asking for some references or asking specific questions about them. If you wanted to discuss alternative theories you would need to provide a valid reference. If you wanted to do alternate theory development then this isn't the place.

 

[jonjacson]

I was curious had you posted again. In my post on the thread I listed three other formalisms if you are interested. I think from the phrasing of your OP to others it sounded like you were trying to propose a new formalism.

Yeah I was looking for that. Thank you very much.

No, I didn't propose anything, just wanted to know solid, well accepted and respected official formalisms.

 

[Kolmo]

Yeah I was looking for that. Thank you very much.

No, I didn't propose anything, just wanted to know solid, well accepted and respected official formalisms.

Note they are listed in order of decreasing use across subfields. By far the most important one to learn is the Path Integral formulation. The second is only used in more mathematical treatments of physics and the third is only used in some areas of quantum information.

 

[atyy]

Note they are listed in order of decreasing use across subfields. By far the most important one to learn is the Path Integral formulation. The second is only used in more mathematical treatments of physics and the third is only used in some areas of quantum information.

But as you said on the other thread, those are equivalent to the Hilbert space formalism, so the Hilbert space formalism cannot be disallowed.

 

[atyy]

Like Lagrangian mechanics, Hamiltonian mechanics is equivalent to Newton's laws of motion in the framework of classical mechanics.

That's why your question was nonsensical. If formalisms are equivalent, you cannot say that one of them is disallowed if their equivalent formalisms are allowed.

 

[Kolmo]

I think "disallowed" was just an unfortunate phrasing of "if you were not using it". The OP was really just asking "what are the other formalisms" in a confused way.

 

[Milsomonk]

I think the title of your thread "Do we really need the Hilbert space for QM?" was a reasonable question and this was the question I chose to answer in my response. Indeed I think you were advised of a number of other approaches to QM that may be the answer you were looking for. I'm not entirely convinced that my own suggestion of the geometric algebra approach could be described as a Hilbert space in disguise but perhaps that is a subject for another thread.

I would agree that the rest of your initial post, ("lets play this game", "disallowed") perhaps unintentionally muddied the waters of the question you were quite reasonably trying to ask.

 

[weirdoguy]

personal attacks

attacking people

Um, where? I see 0 (zero) attacks. But, yes, I do agree that purpose of your thread was a little bit misunderstood.

 

[DaveE]

I think part of the problem was that your question was nearly impossible to answer. Similar to asking "What if there was another universe with different physical laws, what would it be like?" The answer could be anything. It may have been more appropriate in the Science Fiction Forum. I'm sure that's not what you intended, but that's how it appears to a bunch of physicists.

 

[Nugatory]

@Justice Hunter I presume that this complaint was partially motivated by the closing of this thread?

Relativity is one of the most fascinating and elegant ideas that humanity has ever come up with, and just about everyone who has put in the effort required to understand and appreciate it is glad that they did. It's up to you whether you want to try it for yourself... but if you do, a necessary first step is listening when people who have already been there tell you that you're on the wrong track.

 

[Ibix]

you can describe physics without math, let alone the actually math that's currently used.

You can describe physics (edit: kind of, anyway) without maths, but you can't do physics without maths.

geodesics [...] are just lines connecting points together on a geometry

Even interpreting "on a geometry" as meaning "on a manifold", that description misses out an awful lot. The correct definition is that a geodesic is a path that parallel transports its own tangent vector.

you can literally make any language to describe any mathematical abstraction.

Sure. Now see if you can write ##G^{\mu\nu}=\frac{8\pi G}{c^4}T^{\mu\nu}## in English (or other natural language of your choice) in the twelve characters it took me to write it in maths. For extra credit, use your natural language version to make quantitative predictions of something. When you've done that, then you can say that you don't need maths to do science and expect me to keep a straight face.

the typical response from the ego-strokers is that your question was "stupid" or that "it doesn't make sense."

jonjacson's question was just badly phrased, I think. Yours this afternoon was based on a quotation that was nothing more than a catastrophic misunderstanding of relativity, and you wouldn't listen when we kept pointing out that the whole basis of the thread was nonsense. You aren't obliged to listen to us, of course, but it makes me wonder what purpose you thought asking questions would serve if you were only going to listen to answers that didn't point out the problems with what you asked.

 

[Vanadium 50]

Well, Mr. Hunter, we have on the one hand one group of people who have studied a subject, in some cases for years. On the other we have someone who has not even studied the subject but thinks the first group is wrong.

Who has the problem with ego?

 

[fresh_42]

Anyway...so the typical response from the ego-strokers is that your question was "stupid" or that "it doesn't make sense."

This is only an abbreviation. But you are right. Maybe we should take the time and respond in the extended version:

"Your question reveals that an appropriate answer would require holding several lectures in several fields, beginning on a very elementary level. Unfortunately, this isn't something we could provide, despite our continuous efforts to teach and help students."

We can talk about a theory of everything, but we cannot do it with more than a handful of people and in a language, all others won't understand. Any other form would only be small talk and very likely nonsense.

 

[PeterDonis]

it is possible to have several mathematical formulations of the very same discipline

Yes, it is possible. But "possible" is not the same as "guaranteed". Nor is it the same as "known".

We know multiple formulations of Newtonian mechanics are possible because we know the formulations. Nobody knows a formulation of QM that doesn't involve Hilbert spaces. So asking what such a formulation would be like is pointless, since we don't have one to go look at. As I said in the thread, if you don't like that, then go invent a non-Hilbert space formulation of QM, the way Hamilton invented his different formulation of Newtonian mechanics.

 

[PeterDonis]

They are allowed to insult you personally

If you think someone else pointing out where you are wrong, or where what you are saying doesn't make sense, is an insult, you need to adjust your attitude. We are not responding to you personally. We are responding to the statements you make in your posts, which are about physics, not about you.

 

[PeterDonis]

I'm not entirely convinced that my own suggestion of the geometric algebra approach could be described as a Hilbert space in disguise

Geometric algebra is not just a different formulation of quantum mechanics; it's a different formulation of all of physics (or at least it claims to be). So it's not really comparable to the different formulations of QM alone, or QM/QFT. It's more comparable to, say, spin foams or loop quantum gravity, which are attempts to encompass all of physics, not just QM.

 

[Justice Hunter]

You can describe physics (edit: kind of, anyway) without maths, but you can't do physics without maths.

And the OP's question wasn't whether you can do physics without math...it's whether there is a formalism that exists that doesn't use Hilbert Space.

Like I said in my response, you can describe QM with any language...and what's variable is the approximation of that description. You can describe QM by saying "It's particles acting like waves bro" and you can make predictions based on that information...how accurate those predictions are is going to be based on how well the description is formalized. Math is no different, and approximates QM to the best of current human knowledge...doesn't mean a BETTER or even DIFFERENT formalism doesn't exist out there.

Great example, Fine Tuning and Renormalization. Do you really think this is going to fly forever? Of course not, someone is going to come along, with some other model that better describes nature so that you don't have to put "off by 120 orders of magnitude" in fine print on your observables.

 

[PeterDonis]

the OP's question wasn't whether you can do physics without math

Which is irrelevant since the one who made that claim and is getting pushback about it is you, not the OP of this thread.

You can describe QM by saying "It's particles acting like waves bro" and you can make predictions based on that information...how accurate those predictions are is going to be based on how well the description is formalized.

Um, "formalized" means "math". "Particles acting like waves bro" doesn't predict anything.

 

[Justice Hunter]

"Particles acting like waves bro" doesn't predict anything.

Okay you tell me "Particles act like waves bro"

I can say Prediction: "Okay bro then sticking a particle through a double slit will produce an interference pattern, just like other waves."

So yea, you can predict things in languages that aren't math...how accurate is the prediction is based on the level to which it's formalized. QM predictions are accurate to with 10^12 decimal places, not so much using English but that all depends on how well you describe it. You describe it well enough, you can get more and more accurate predictions.

That's what...thought experiments are for...such a novel idea right?

 

[PeterDonis]

I can say Prediction: "Okay bro then sticking a particle through a double slit will produce an interference pattern, just like other waves."

But a particle going through a double slit does not produce an interference pattern. It produces a single dot on the detector screen. So your prediction is wrong.

 

[Nugatory]

You can describe QM by saying "It's particles acting like waves bro"

Yes, if we're talking to our little bro and want to mislead him. But the only people who would consider that a description of QM are people who have no idea what QM is. To be fair, they'd be in good company - there are a lot of bad popularizations out there.

Quantum mechanics does not (as least for me - tastes vary) have the same compelling beauty and elegance as relativity. Nonetheless, my comment above ("just about everyone who has put in the effort required to understand and appreciate it is glad that they did. It's up to you whether you want to try it for yourself... but if you do, a necessary first step is listening when people who have already been there tell you that you're on the wrong track.") applies to quantum mechanics as well. If you're starting with the idea that it's particles acting like waves, you're taking a wrong turn that many physicists took at the beginning of the last century, but recognized and abandoned a few decades later. What do you have to lose by listening to people who have already been through it?

 

[Justice Hunter]

But a particle going through a double slit does not produce an interference pattern. It produces a single dot on the detector screen. So your prediction is wrong.

Then, instead of saying "a particle", you say "a stream of particles" and now that sentence is more formalized, and you make a more accurate prediction, because a stream of particles will create an interference pattern.

"Okay bro then a stream of particles through a double slit will produce an interference pattern, just like other waves."

Now you have a "more accurate prediction" by replacing a term with a better term, proving the point...Such a sentence could have been a mathematical sentence, and the same thing happens. The better the formalization, the more accurate the predictions and that's science in a nutshell...

How do you think cavemen made predictions? They didn't fuss and fight with each other over General Relativity and QM in order to understand the trajectory of a spear or rub a couple rocks together. Over time, with better formalization they begin to know more and more about the world to better and better accuracy...

 

[Ibix]

And the OP's question wasn't whether you can do physics without math.

I was replying to you, not the OP. You quoted someone (unattributed, although it looks like vanhees71's writing) as saying that you can't do physics without maths, then described this as "silly" because you can describe physics without maths. I was pointing out that doing and describing are rather different things.

You can describe QM by saying "It's particles acting like waves bro"

Not if you want to do anything useful with it, as your last few posts exchanged with PeterDonis have rather nicely illustrated.

Math is no different, and approximates QM to the best of current human knowledge...doesn't mean a BETTER or even DIFFERENT formalism doesn't exist out there.

You'll notice that, even when there are different formalisms for something, all of them are mathematical formalisms. We don't do that just for fun or to make a barrier to entry. It's genuinely the case that maths is the only tool we have that allows us to make clear, precise, testable predictions. If you want to claim otherwise the burden is on you to produce an example of such a model.

Great example, Fine Tuning and Renormalization. Do you really think this is going to fly forever? Of course not, someone is going to come along, with some other model that better describes nature so that you don't have to put "off by 120 orders of magnitude" in fine print on your observables.

And do you really think that the better model will be non-mathematical? How will it predict the numbers on our instrument scales?

How do you think cavemen made predictions?

Largely by blaming anything they didn't understand on the gods, I believe.

Over time, with better formalization they begin to know more and more about the world to better and better accuracy...

So, you want to try to understand quantum mechanics using the intellectual tools available to cavemen? Or you think you can only understand something if you start with "Zog bang rock together, make spark" and work your way up from there? Why not just use the tools that are known to work?

 

[PeterDonis]

"Okay bro then a stream of particles through a double slit will produce an interference pattern, just like other waves."

Which is still wrong, because the interference pattern is not continuous, like a pattern caused by waves is; it still resolves into little dots, one for each particle. And if you slow down the source so it only emits one particle at a time, each particle makes a little dot, and over time the dots build up the interference pattern.

How do you think cavemen made predictions?

Physics is not just about "making predictions". It's about making quantitative, testable, accurate predictions. Cavemen's predictions were (sometimes) testable, but not quantitative, and very often wrong (as the comment by @Ibix illustrates). That's why they never got systematized the way physics is, and why they never led to the kind of technological advances that physics has produced.

 

[Justice Hunter]

Yes, if we're talking to our little bro and want to mislead him. But the only people who would consider that a description of QM are people who have no idea what QM is. To be fair, they'd be in good company - there are a lot of bad popularizations out there.

Quantum mechanics does not (as least for me - tastes vary) have the same compelling beauty and elegance as relativity. Nonetheless, my comment above ("just about everyone who has put in the effort required to understand and appreciate it is glad that they did. It's up to you whether you want to try it for yourself... but if you do, a necessary first step is listening when people who have already been there tell you that you're on the wrong track.") applies to quantum mechanics as well. If you're starting with the idea that it's particles acting like waves, you're taking a wrong turn that many physicists took at the beginning of the last century, but recognized and abandoned a few decades later. What do you have to lose by listening to people who have already been through it?

If the conjecture on the thought experiment in my thread was actually addressed, I definitely wouldn't have minded discussing that and being wrong, but the responses to my thread was everything but attacking the conjecture...and instead was merely stating the obvious of what was already known about relativity before subsequently being deemed a heretic and thread closed...

I'm not going to talk about my thread, it's already closed, and I'm not derailing this one. This thread is about how "science advisors" know a lot about science, but know very little about advising. You might as well close the forum to anybody who isn't a science advisor because you censor any question that isn't a specific question, which nobody really knows what kind of questions you guys will actually discuss...but I'm inclined to open up another thread right now on all the problems with the standard model just to rub those problems back in your faces...because yes those questions are the questions that people actually care about, and are the obstacles the standard model faces, and to censor them would be the ultimate "proving me right" about the overall censorship program going on here in this forum.

 

[etotheipi]

"Zog bang rock together, make spark"

Don't know why that made me laugh so much. That's how I feel, like, 65% of the time doing physics.

 

[Ibix]

This thread is about how "science advisors" know a lot about science, but know very little about advising.

Interestingly, the OP actually agreed (in post #6) that he had got useful help from one of the advisors you are talking about, despite asking a question in a way that mislead the rest of those who responded.

Don't know why that made me laugh so much. That's how I feel, like, 65% of the time doing physics.

Yeah, but on the rare occasions that you're banging two bits of chalk together and Peter suggests you try flints, you listen...

 

[Nugatory]

and instead was merely stating the obvious of what was already known about relativity

And what else would you expect from a forum whose purpose is:

Our mission is to provide a place for people (whether students, professional scientists, or others interested in science) to learn and discuss science as it is currently generally understood and practiced by the professional scientific community.

 

[Justice Hunter]

Yeah, but on the rare occasions that you're banging two bits of chalk together and Peter suggests you try flints, you listen...

Yes. You must obey everything Peter says as gospel because he knows all things and is god.

Believing someone for no reason other then their position or authority on a subject is no better then believing in a priest who preaches religion.

Should OP take your word for it that there is no other formalism of Quantum Mechanics? Then low and behold 10 years later someone comes up with another, better formalism on Quantum Mechanics.

Think you'd fit in well with the folks who couldn't stand the thought of heliocentric world view, and refuse to believe Earth can't POSSIBLY be anything other then center of the Solar System. Any other view is heresy and must be burnt at the stake, and be silenced.

Again this isn't about how much science you know, this is about how you advise, respond to questions and silence them without actually analyzing the question really. I mean can you even prove that there is no other models or ways to describe* QM that don't use Hilbert Space?

 

[fresh_42]

Yes. You must obey everything Peter says as gospel because he know all things and is god.

Nobody has to. It is everybody's own choice to take the opportunity to learn something, or not.

Believing someone for no reason other then their position or authority on a subject is no better then believing in a priest who preaches religion.

That would be stupid indeed. The fact is, that one can deliver evidence whilst the other one can not. It is the evidence, not the person people are expected to believe in.

Should OP take your word for it that there is no other formalism of Quantum Mechanics? Then low and behold 10 years later someone comes up with another, better formalism on Quantum Mechanics.

Here you confuse present, past, and future. Nobody claimed that there won't be such a model any time in the future, only that none is known as of now.

Think you'd fit in well with the folks who couldn't stand the thought of heliocentric world view, and refuse to believe Earth can't POSSIBLY be anything other then center of the Solar System. Any other view is heresy and must be burnt at the stake, and be silenced.

Well, the folks with the heliocentric worldview have had the better arguments. Problem is, you have none, hence your comparison is purely rhetorical, which by the way breaches our rules, too, since it is an ad hominem argument. The last exit of all who fight a lost cause.

Again this isn't about how much science you know, this is about how you advise, respond to questions and silence them without actually analyzing the question really.

See my post #18.

I mean can you even prove that there is no other models or ways to describe* QM that don't use Hilbert Space?

See above.

 

[Dale]

Any other view is heresy and must be burnt at the stake

This is silly. You are actually comparing the “injustice” done to you in having a thread closed with tying someone alive to a pole and lighting a fire under them until they die from burns and from inhaling superheated air. As though people, if offered a choice between having a thread closed and being burned to death, might have some indecision. This comparison is ludicrous.