The h Bar

2:01 PM

@0celo7 An hour really isn't that bad. That's actually kinda the average time one spends on an homework exercise here, I think - if it is easy ;)

@bolbteppa Ah, so you decided the spherical harmonics are SO(3) rather than SU(2), after all? Minor nitpick: You should write what the range of the functions on X

Sofia

@ACuriousMind good morning! You woke up now?

ACuriousMind

@Sofia It's the nature of debate that one has to be confrontational. I'm not bothered by that. :)

And I've been awake for a bit, but yeah, you could say I got up about now.

Sofia

@ACuriousMind you know, you use words too sophisticated for me. In fact I notice that all of you do. I am no more at the Institute, I am for a couple of years at home because of family problems. But I don't remember my teachers and friends speak in the way I see you do. It's probably the way of the new generation.

@ACuriousMind confrontial = a bit aggressive , do I guess correctly ?

ACuriousMind

@Sofia Yes, a bit aggressive fits

And I think the difference is that people tend to write more sophisticated than they would speak, because they have time to think about their words

If your main experience with English is spoken, then it's no wonder you rarely encountered these words

@DanielSank Oh god, wouldn't that just lead to endless fighting?

Sofia

2:25 PM

@MarkMitchison you say There is only a "crisis" if you accept realism. So most people prefer not to. "Crisis solved". No, Mark, I am ready to abandon anything, realism, whatever you'd say. But these entanglements are in clash with the basic rules of our logic.

ManishEarth

@Sofia btw, try to be more attentive in reviews :)

physics.stackexchange.com/review/suggested-edits/74202

ACuriousMind

@Sofia You really should look into epistemology (the philosophy of knowledge). What you call logic is indeed a specific philosophical viewpoint called realism. It's not logic, but one specific logical system out of several.

Sofia

@ACuriousMind my dear one, wait a bit, ManishEarth is displeased with something, I need to see what's the problem.

@ManishEarth yes, what displeases you? please be more clear.

ManishEarth

@Sofia that edit totally rewrote the answer and changed it from an answer to a comment

Sofia

@ManishEarth Aaaa! And what should we do in this case? The edit was very interesting. I would gladly retain the edit.

ManishEarth

2:31 PM

@Sofia reject it

It made the answer worse, went off topic, and was a complete rewrite

Sofia

@ManishEarth some other idea? Reject an interesting thing?

ManishEarth

Um, that's an edit

ACuriousMind

Your heart is too soft for the internet, really :D

ManishEarth

Look at the content that was removed

Kyle Kanos

Just compare the amount of red to the amount of green

Sofia

2:33 PM

@ACuriousMind (this is why the people around me, love me)

ManishEarth

There was a pretty clear answer, and it was replaced completely

Also I don't see much interesting about it :p

Sofia

@ACuriousMind aye! In fact I didn't understand to whom you said that has a soft heart. If is wasn't to me I'd delete my reply.

ACuriousMind

@Sofia You! Just because you think something is an interesting story, that doesn't mean it's a valid edit or answer. In fact, that edit is totally invalid because it replaces an accepted objective answer with a personal story.

It's like me editing one of your answers to tell everyone about that time I saw the double-slit experiment.

Sofia

@ACuriousMind , @ManishEarth , you tell me what to do with that edit. How to preserve it.

ManishEarth

You don't

Kyle Kanos

2:39 PM

Why would you want to preserve it?

Sofia

@ManishEarth I understand that you deleted the answer. So, what was done cannot be undone. But, in the future, we have to find ways to preserve interesting items. And the fact that you doesn't find it interesting, has no implication on me. I am also a user here.

ManishEarth

@Sofia I didn't delete the answer

That was an edit

ACuriousMind

But we aren't here to collect things that users find interesting!

ManishEarth

Also that

ACuriousMind

We're here to collect physics answers to physics questions.

Kyle Kanos

2:41 PM

@Sofia It wasn't an answer, it was a suggested edit

Sofia

@ACuriousMind ayyyye! Then I'd place a suitable question.

and retain the answer.

Kyle Kanos

It should be a separate answer

ACuriousMind

But the edit contains no interesting physics. It's just "you need a closed circuit" phrased differently

Sofia

@ACuriousMind and it was a perfectly physics question - current of high voltage.

ManishEarth

@Sofia yo ufail to realize two things here:

It may be interesting, but it removed existing good content.

Also, it was mostly anecdotal and less physicsy

ACuriousMind

2:44 PM

Also, no one cares if the writer saw some birds being fried at legoland because they touched each other (what's up with that, anyway?!)

ManishEarth

lol

Sofia

@ACuriousMind ah, you! how to convert from joules to ergs is more interesting> Isn't it?

ACuriousMind

No, it isn't, but it's a physics question

A very bad one, but a physics question

ManishEarth

You're conflating edits with answers and questions

Edits are held to different standards

Also that question would be closed

Sofia

@ACuriousMind what you say! By whose judgement it's aphysics question, more than one on a closed or open circuit?

ACuriousMind

2:46 PM

@Sofia We aren't saying the closed circuit isn't physics, but the stuff that was attempted to edit in wasn't physics

Oh

Sofia

@ACuriousMind where did you learn about closed and open circuits? Not in a course of physics?

ACuriousMind

You do realize that *this* was the text you are calling "interesting", right?
"Good question. When birds sit or stand on wires the wires energy or electricity doesn't flew to their bodies which is called an open circuit. If two birds hold hands and sit on the wire, they both create a closed circuit. That's when electricity flows through the two birds with make them not alive. I have seen this before I entered legoland at San Diego. Hoped this answered a really good question!"

And *this* is the text that was to be deleted:
"You will not get a shock unless you complete the circuit to ground. This is why power lines can be worked on while live, from a helicopter: [Helicopter Power Line Maintenance](http://www.youtube.com/watch?v=chpOgJwqBXU)"

Danu

@JerrySchirmer? ah, no ping :(

ACuriousMind

You approved replacing the latter text with the former.

Danu

If I'm not having a massive brainfart right now, there is a funny error in the dedication of your thesis: "...and whose help I am incapable of understating."

...this means they were completely useless, no?

Sofia

2:49 PM

@ACuriousMind an analogy: why does the paper on a book fall together with the book. I saw it when my cat pushed the book.

ACuriousMind

@Danu lol

@Sofia This isn't at all about the question, it's about the edit.

Danu

@ACuriousMind ...right?

ACuriousMind

@Danu Yeah, it's a totally passive-aggressive statement that they weren't any help at all :D

Sofia

@ACuriousMind then we speak of different things, but if you deal with 5 issues at once, how can you be focused? I spoke of retaining that edit in some way, to find a way to keep it.

Danu

@ACuriousMind Gotta love it

ACuriousMind

2:51 PM

@Sofia Yes, but you cannot just approve replacing another person's answer with it!

Kyle Kanos

@Danu That's not the way I read that

It reads To X and Y...whose help I am incapable of understating

oops

Sofia

@ACuriousMind I already suggested to place for an interesting edit, a suitable question.

ACuriousMind

@KyleKanos Hahahaha

Kyle Kanos

Man my reading is off lately :(

It means that their help was so great that he can't express in words how much of a help they were

Sofia

@ACuriousMind and if it seems so trivial to you the issue with the open or closed circuit, there is an electricity question that none of us was able to solve --- which is a shame for our site. So, would you give a hand of help?

ACuriousMind

2:54 PM

@Sofia Alright, but we don't have such a mechanism, regardless of whether that content was worth preserving or not (it wasn't). So if you go to the review queue to review such edits, you must be prepared to reject them regardless of what you think about the content.

Kyle Kanos

@ACuriousMind That should be mostly bold font

ACuriousMind

Because surely the author of the original answer doesn't deserve to have their answer deleted, right?

Danu

@KyleKanos right ;)

Kyle Kanos

Anyway...thanks for the pointer to his Thesis

Danu

@KyleKanos That'd be the case if he was incapable of over-stating their help

...but yeah, that's obviously the idea

Sofia

2:57 PM

@ACuriousMind We are far past this point. I don't argue with the law. I was just thinking how to retain something nice, some creative way.

Kyle Kanos

@Sofia Don't think about retaining "nice things"

Think about what the suggested edit is doing to the post

Sofia

@KyleKanos we are past this. I said already, I don't argue with the law.

ACuriousMind

I really don't see what's nice about a story of two birds being killed by electricity?! The physics content of this is just "You need a closed circuit to get shocked", which is already there in the original answer.

Danu

@ACuriousMind LOL. What's this discussion about?!

ACuriousMind

(I'm also not sure if it really works this way, I think not.)

@Danu physics.stackexchange.com/review/suggested-edits/74202

Kyle Kanos

3:00 PM

Australians are crazy: digitaltrends.com/cool-tech/…

ACuriousMind

I mean, birds usually have two feet on the voltage line without getting fried, why would two birds with four feet total on the same line suddenly get fried?

Danu

"I have seen this before I entered legoland at San Diego. " very insightful

also, birds don't have hands

ACuriousMind

@Danu Shhh, details!

Sofia

@ACuriousMind If you don't see what's nice, wait a bit, and I'll give you something (hopefully) nice, than vzn gave me, and I was very surprised.

ACuriousMind

@Danu Perhaps the author meant bird = girl? Isn't that an UK thing? :D

Danu

3:02 PM

@Sofia That edit was really bad

@ACuriousMind Heh, yeah

ACuriousMind

That makes the story even more horrible

Danu

Traumatized @ Legoland

(although San Diego is not in the UK)

Sofia

@ACuriousMind the Bohm guiding wave, i.e. guiding a particle, was implemented.

ACuriousMind

@Sofia: Don't change the topic. I said this particular edit is worthless. Not even Bohm's guiding wave is going to change that

(I also read the articles on that, and I'm not sure why everyone is amazed that a water droplet can follow a guiding wave on a surface)

Danu

@KyleKanos reading the intro to Jerry's thesis, I cannot help but recall the discussions recently had in this room on notation, hah

Sofia

3:05 PM

@ACuriousMind , what you may want from me more than what I said that I will respect the law?

Kyle Kanos

@ACuriousMind Because it proves Bohm right :D

ACuriousMind

@Sofia Well, I don't want you to do anything, but you said the edit was worth preserving, and I and the rest of the room disagreed.

Danu

@Sofia Maybe you just need to respect his authoritahhhh

(am kidding)

Sofia

@ACuriousMind , @KyleKanos it doesn't prove Bohm yet. But it leads us immediately to think that Bohm might have been right.

Danu

Any links I should read on this? I want to confirm my suspicion that it's nonsense :P

Mark Mitchison

3:08 PM

@Sofia What? It just proves that mathematical models of reality can predict physical phenomena. We've known that since Galileo.

Bohm's theory is already consistent with QM. These experiments change nothing.

Sofia

@ACuriousMind , when Glileo disrespected the church, did he consider that he had to respect an authority? Mind is free

ACuriousMind

@Sofia Why? I would never have doubted that things can follow actual guiding waves. I don't even doubt that Bohm's interpretation reproduces all of QM. I just don't see the point of using such a convoluted guiding wave theory when we can just do Hilbert spaces + Born rule.

Danu

@Sofia I was kiiiidding please dont take it seriously :P

This thesis by Jerry seems really nice :)

Sofia

@MarkMitchison , @ACuriousMind , Noooo! No! Bohm's interpretation is at odds with relativity.

ACuriousMind

In essence, I say there's nothing Bohm, or Everett, or other interpretations ever can be right about, because they have yet to show me a single actual experiment where they differ in their predictions

@Sofia Normal QM also is at odds with relativity. Relativistic QM is just a smoke-and-mirror trick of doing QFT without telling anyone.

Sofia

3:11 PM

@MarkMitchison , @ACuriousMind It's either relativity, or Bohm (at the quantum level, of course, not in the macro-world.

Mark Mitchison

@Sofia No it isn't. It's at odds with the philosophical principle of relativity. It's no more at odds with relativity than standard QM. And Bell extended the idea of beables to relativistic QFT without enormous problems.

@Sofia You are wrong. Although there exists a privileged frame in Bohmian mechanics, it is unobservable.

Sofia

@ACuriousMind *** I know*** a prediction in which Bohm and standard QM differ. I can't tell you at this time.

ACuriousMind

And yes, if you do it properly, you can, not surprisingly, build relativistic QFT-style theories with every interpretation. If you couldn't, people wouldn't defend them at all.

Mark Mitchison

Bohmian mechanics is operationally the same as QM by construction.

Kyle Kanos

@ACuriousMind Is that true?

The second sentence, I mean

Sofia

3:13 PM

@MarkMitchison Nooo! There IS a difference. But I can't tell you at this time.

Kyle Kanos

@Sofia Why not?

Mark Mitchison

@KyleKanos If you couldn't make an interpretation consistent with QFT then it's not an interpretation. It's a falsified scientific theory!

Sofia

@ACuriousMind , @MarkMitchison and there exist experiments, already done, that can tell us.

Mark Mitchison

@Sofia I'd be curious to see that.

Kyle Kanos

@MarkMitchison True. But I like playing Devil's Advocate with ACuriousMind about Bohmian mechanics

Sofia

3:15 PM

@KyleKanos why not what? I lost you.

Kyle Kanos

@Sofia Why can't you tell us?

Mark Mitchison

@Sofia If you click on the little arrow on the left of Kyle's comment, you can see what he is replying to.

ACuriousMind

@KyleKanos A bit hyperbole, but the Dirac equation is very ad hoc if you don't derive it from a QFT Lagrangian. I have never seen a satisfying derivation of it that doesn't use weird ideas like "square root of Klein Gordon", while it arises naturally from the kinetic term for 1/2 particles.

Danu

Am I the only one who thinks that Bohmian mechanics was explicitly designed to never disagree with 'standard QM'?

ACuriousMind

@Danu No

Mark Mitchison

3:16 PM

Look up a few lines, I said: Bohmian mechanics is operationally the same as QM by construction.

Danu

...because then you are certainly wrong @Sofia

@MarkMitchison Okay, good

Kyle Kanos

@Danu Well, I would say yes. It's designed as an alternative, so it must make the same predictions as 'standard' QM

Sofia

@KyleKanos it's in work, it's an article on which I work. And it requires an experiment that has to be done, similar to experiments done now. So, QM is likely to predict one thing Bohm another.

Mark Mitchison

@Danu However, I do not believe that people working on Bohmian mechanics now feel the same way.

Danu

@MarkMitchison But is this really a matter of opinion?

Mark Mitchison

3:17 PM

The point is to reproduce known experimental results while predicting differences in thus far inaccessible parameter regimes.

ACuriousMind

@Sofia Then show us. As a nice comment said: Physics is the search for fact. That which is asserted without evidence can be dismissed without evidence.

Danu

Did Bohm make comments on this?

@MarkMitchison Oh, okay

Sofia

@Danu don't be malicious with me.

Jimdalf the Grey

@ACuriousMind Do you have proof for that statement?

Mark Mitchison

@Danu Bohm wrote a whole book about it. He certainly wanted to make it a falsifiable theory.

Sofia

3:18 PM

@ACuriousMind patience!!!!!!!!!!!

Mark Mitchison

But I think modern Bohmians rather distanced themselves from Bohm's interpretation.

In particular, Bell's reformulation of Bohmian mechanics in terms of a guidance relation is probably a bit more satisfying than the quantum potential.

Depends on what you prefer I suppose.

ACuriousMind

@JimdalftheGrey I knew someone would ask that

Kyle Kanos

There's a faculty here at my University who specializes in Pilot Wave theory for quantum cosmology. His talks are rather interesting

Sofia

@MarkMitchison, @ACuriousMind, @Danu, @KyleKanos Bohm predicts trajectories. Standard QM forbids.

Jimdalf the Grey

@ACuriousMind Of course it had to be me

Mark Mitchison

3:21 PM

@Sofia So what?

This has nothing to do with experiments.

ACuriousMind

^that

Mark Mitchison

It's a matter of interpretation.

Sofia

@MarkMitchison , @ACuriousMind, @KyleKanos patience!!!!!!

Jimdalf the Grey

Let's wait

Mark Mitchison

I think everyone here understands Bohmian mechanics equally well. Unless you can produce an operational procedure for which the predicted outcome is different, then I don't believe there is a difference.

Jimdalf the Grey

3:22 PM

@Sofia are you currently in the process of procuring proof?

Kyle Kanos

But wasn't that the point of the excitement of that water-droplet experiment? That it showed the droplet followed a wave along a trajectory that (after some time) gave a decent representation of the probability distribution

@JimdalftheGrey That's what I'm getting out of her comments

ACuriousMind

@Sofia I have all the patience in the world, but you can't make assertions without substantiating them.

Danu

@MarkMitchison I think I understand almost 0 of Bohmian mechanics ^^ I never felt the need to study it

ACuriousMind

@KyleKanos Yes, but no-one ever doubted that following the guiding wave reproduces probability distributions because that is what Bohmian mechanics does!

Sofia

@JimdalftheGrey yes! But it requires a very delicate experiment. Such experiments are currently done, but of course, not with the purpose of what I need.

Jimdalf the Grey

3:24 PM

If Sofia is getting the proof and asks us to wait in the meantime, then saying one can't make assertions without substantiating them is pointless as Sofia is in the process of attempting to substantiate them. All you can do is wait

Sofia

@ACuriousMind patience!!!!!!!!!!!!!!!!!

Danu

@ACuriousMind on my diffgeo test I was asked to show that for some explicit example, the volume form on a submanifold was just given by the volume form of the bigger manifold, restricted to the embedded submanifold. Is this philosophy much more general? Yes, right?

@Sofia ...relaaaaax... :)

ACuriousMind

@KyleKanos: The issue is that, in quantum experiments, you cannot see the droplet, you only see the probability distribution. So the droplet experiment tells us nothing, because you also get the probability distribution from every other interpretation

Jimdalf the Grey

@Sofia but if you're simply waiting on an experiment that has yet to be completed, our patience has limits. We can wait an hour or a day. Any more than that and you might need to rethink making your assertions at this moment in time

Danu

@ACuriousMind I'm asking because of some statements in Jerry's thesis which seem to have the same idea

ACuriousMind

3:26 PM

@Danu Oooof. I would think so, but I'm always afraid of pathological cases

Sofia

@JimdalftheGrey much more than what you say. At least of the order of months.

ACuriousMind

@Danu: Of course, you need to take a submanifold that has a volume form, i.e. is at least orientable.

Sofia

@Danu who told you that I am not relaxed?

Danu

@ACuriousMind Yes, yes

@Sofia YOUR SHOUTING!!!!!!!!!! ;)

ACuriousMind

@Sofia The amount of exclamation marks seems to indicate otherwise ;)

Jimdalf the Grey

3:28 PM

@Sofia Yes, then saying "patience" is not warranted here.

Sofia

@Danu Who told you that I am shouting?

Danu

@Sofia Your exclamation marks.

englishclub.com/writing/punctuation-exclamation-mark.htm

"An exclamation mark usually shows strong feeling, such as surprise, anger or joy. Using an exclamation mark when writing is rather like shouting or raising your voice when speaking."

ACuriousMind

@Danu Then this sounds suspiciously like a cohomological statement, because the volume form can be seen as "just" a special element of the top cohomology.

Sofia

@JimdalftheGrey whatever I am saying is that Bohm's mechanics is a very serious thing, and we can't exclude the fact that one day we may pass from standard QM to Bohm.

ACuriousMind

I bet there's a nice algebraic way to see this ;)

Danu

3:31 PM

@ACuriousMind Jerry has similar statements on metrics, for what it's worth

ACuriousMind

@Danu Well, isn't the metric on a submanifold defined to be induced by the outer manifold?

(And the volume, now that I think of it)

Danu

Yeah, but it's not completely obvious that one can just 'skip' using the pullback

ACuriousMind

Ah

Danu

...I guess this always works though

I recall some statement to this effect in an appendix of Carroll

Sofia

@ACuriousMind , @JimdalftheGrey , @MarkMitchison and what I am also saying is that there were a physicist that didn't admit shut up and calculate, but offered a possible alternative, which, by the way, is very appealing. Though, only the experiment can say if it is correct.

ACuriousMind

3:36 PM

@Sofia Well, if you claim that Bohm makes different predictions from QM, then it becomes a new theory instead of an interpretation. Then, the shut up and calculate approach is very interested in seeing that prediction, and, even more, in seeing the experiment.

Jimdalf the Grey

@Sofia I'm not arguing with you nor do I care about this subject right now, I'm merely saying that asking for patience when you are not personally working towards providing the substantiation they are looking for is not the best of ideas. If you want to keep arguing with them over the issue, that's none of my concern

ACuriousMind

Shut up and calculate doesn't mean that you say "QM, as it is now, is the eternal truth". It means you don't care for words that don't make any difference in experiments.

Jimdalf the Grey

@ACuriousMind It also could mean you have a particularly distracted and chatty officemate.

3

ACuriousMind

@JimdalftheGrey lol

Jiminion

I'm kinda liking Bohm mechanics, especially cuz this guy does not....
http://motls.blogspot.com/2013/07/bohmian-mechanics-ludicrous-caricature.html

ACuriousMind

3:46 PM

@Jiminion Hah. That's not a reason to like or dislike anything in science, though.

Kyle Kanos

@ACuriousMind Eehhh. IDK about that

When it comes to competing theories, there really isn't any scientific reason to like or dislike one

So you have to depend on what others think/say about it to make your decision (if you want to make one)

ACuriousMind

@KyleKanos You've got a point there

Kyle Kanos

So why not take a contrarian position to someone you're not fond of?

Jiminion

@ACuriousMind That's not the ONLY reason.

Sofia

@JimdalftheGrey Yes, I am working on that, and I can even tell you that there are experiments of the type I need. My difficulty, when the article is ready, is that I have family problems and I can't take the bags and fly to the place where such things are done. So, for the moment I can't say more.

Jiminion

3:50 PM

take the bags = pack (I think) I like the way Sofia says things.

What is "The Event" ? (in 10 minutes)

Jimdalf the Grey

Chat event

every 2 weeks

we discuss important issues if anyone has any

Richard

Is there a topic?

Jimdalf the Grey

I don't know, I'm usually suspiciously absent during it

Richard

Sounds wise.

ACuriousMind

Mh, we haven't had any controversial meta post lately, have we?

Jimdalf the Grey

3:54 PM

we had the editing closed questions one

Richard

I actually have a few physics questions but I don't know how to frame them, or even whether they're just stupid.

Jimdalf the Grey

@ACuriousMind I believe it's your turn to field prospective questions

Kyle Kanos

@Richard Fee free to ask them

Jiminion

@Richard Remember, there are no stupid questions, except for the really stupid ones.

5

:)

Danu

@Richard Just ask in chat

ACuriousMind

3:57 PM

@JimdalftheGrey What? I think I'm already chatting enough here without also taking over chat session :D

Richard

They're about black holes. 1) Can you tear them apart? 2) Could you be inside one without noticing? (for example in the centre of a trinary system) 3) Must a black hole have a singularity?

I've had a quick look and the don't look dupey.

John Rennie

@Richard Have a look at ...

1

Q: Can a sufficiently large black hole be singularity-free?

This came to me after reading that a black-hole that has the mass of the observable universe will also have an event horizon that covers the observable universe. Since the definition of a black hole is that nothing can escape from it, does it actually require for it to have a single singularity ...

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