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1:15 AM
I don't mean to be annoying, but this question now has four answers that all seem to me to answer a different question. One answers the question in the title, one discusses the Bohmian/orthodox mix, one is about time evolution, and the newest is about why we don't have a probability distribution in QM.
And I am still unjustified in saying it is not clear what is being asked?
1:29 AM
@ACuriousMind You are (were), on my view, not (never) unjustified in saying that. Having said that, I see that the question has been edited since I first read it but I suspect that my view will not change upon reading the edited version.
1 hour later…
2:41 AM
9 hours ago, by ACuriousMind
But some mathematician named Breast should definitely invent some expansions, math courses always need some terminology to giggle about.
reminds me of the timeless notorious tale of Polly Nomial... (which reminds me of the recent commotion over 50shades at the theaters...)
3:15 AM
@ACuriousMind Not sure what physics.stackexchange.com/questions/166014/… is asking.
@0celo7 Oh, that's just 12262
They've been around for a bit, and have a very idiosyncratic view on relativity
TIL there are infamous users besides Ray Kay.
I gave up when they introduced nonstandard notation.
They are somehow convinced that relativity should be recast in terms of set of events and distance geometry, as far as I can tell
@ACuriousMind i.e. causal structure? Or something else...?
@0celo7 Mh, not exactly
3:19 AM
Causal structure is all about the topology of sets.
I guess distance is not topology.
They reject the notion that spacetime is a manifold, and want to take as structure only that which can be measured
@ACuriousMind But with a metric manifolds are measurable.
@0celo7 No, empirically measured
And GR manifolds are metrizable.
As in, I have a set of observers that whizz around in space and tell me the proper time between events, and nothing more
At least, that's what I think the idea behind this is
3:21 AM
Lol, there's a quote in Weinberg that I have to find!
He talks about this
Basically, they don't like the idea of a metric and such, and want to work with just a structureless set of events and the invariant intervals between them, I think.
"Adding up these subdistances gives the proper distance $$d_\text{prop}(t)=\int_0^{r_1}\sqrt{g_{rr}}\,dr=R(t)\int_0^{r_1}\frac{dr}{\sqrt‌​{1-kr^2}}$$Obviously, no one is going to organize this sort of cosmic conspiracy, so the proper distance is not very relevant to observational cosmology."
Nice squareroot there :D
Idk what's up with that
What's the "cosmic conspiracy" he's talking about?
3:26 AM
Works in Texpaste
You have to line up a bunch of observers and have them shine lights as soon as they get the signal, without lag.
They have to somehow sync all the times and figure out the distance
And they have to be infinitesimally close.
That...sounds very much like what I think 12262's masterplan is
I can imagine him as the NASA director...
But I'm not really sure, I never had the patience to read what this distance geometry is about, because, although the Wiki article claims it is "immediately relevant" to many things, I've never seen it anywhere else.
3:29 AM
I imagine those "reasons of moderation" are a combination of "non-mainstream" and "unclear what is being asked".
@ACuriousMind It should be pointed out though that spacelike geodesics are possible.
@0celo7 Yeah, read that
Geodesics are stationary points, not extrema.
Not that anyone cares about them.
@0celo7 They've also been known to insist that not only is their choice of language better than everybody else's, but that it is so much better that everybody else is simply wrong.
Or at least that's how I've read it.
A: How to measure the curvature of the space-time?

user12262Following Synge's description of a "five-point curvature detector" 1 and its generalization (e.g. as indicated in [2]), the curvature of five participants ($A$, $B$, $N$, $P$, $Q$) who were and remained (chrono-geometrically) rigid to each other (i.e. finding constant ping duration ratios) is mea...

Oh my god...
lol, don't go down that rabbit hole
3:33 AM
@ACuriousMind Well, he has sources.
Yeah, it's not really crackpottery because this distance geometry and the Cayley-Menger determinants and whatnot are actually things people have thought about
And you can (probably) recast some of relativity in that language
It's just so utterly tedious and unenlightening that I don't see the point at all
@ACuriousMind As you know, my knowledge of analysis is rudimentary. I thought the metric defines our notion of distance. How could you possibly get rid of it?
@0celo7 It's measured :P
And how does one get field equations?
There are always these participants and observers and chronometers and ugly matrices
@0celo7 No idea
I would guess they do not accept the idea of the field equations at all
3:37 AM
I was about to call you a QFT pleb, then I realized no serious relativist would know the answer either.
I think it's kind of an extreme view that only permits you to talk about things you could actually, physically measure
I'm not sure if I hope or fear that they, one day, turn to quantum theory
Hmm...can we actually measure the curvature tensor? Perhaps via geodesic deviation.
@0celo7 But what are you measuring? Distances!
@ACuriousMind You're in serious trouble if they start trying to measure a topological field theory :D
Wait they don't need a metric
You are inferring something about the field/curvature/whatever from the measurement, but all that you really measure is a distance
3:40 AM
My god...they have a point.
Although Zee said in his gravity book that the metric defines our clocks and rulers.
Yeah, it's kinda difficult to argue with that position
@ACuriousMind Since they have to measure with light, any $(n+0)$-dimensional field theory is safe, right?
(Un)fortunately, it's also kinda difficult to argue for anything with that position
@ACuriousMind Or convert to string theory! Dare them to measure the Planck length.
@0celo7 As I said, I have no idea how this reductionist view would approach any kind of quantum theory, or even statistical mechanics.
3:44 AM
12262: Let's measure the circumference of a string! :: Measuring device has quantum wobbles :: 12262: More mass! :: Measuring device turns into a black hole ::
Quantum wobbles = uncertainty principle or something.
@0celo7 If you have an idea for measuring the circumference of a string, I think some theorists would like a word with you.
If you want to measure on the order of the Planck length, your measuring device will turn into a black hole. Or something like that.
I'm gonna go check that calculation in Zee.
Seems legit. It argues from the uncertainty principle and uses the speed of light and the mass of the measuring device to bound the uncertainty in length.
I'm always a bit sceptic when someone waves their hands and says "uncertainty principle"
@ACuriousMind Want me to reproduce it?
But that's not to say such arguments are always wrong
@0celo7 Nah, not now, but thanks
I'm gonna go to bed
3:51 AM
I'm sceptical about $$\hat x(t)-\hat x(0)=\frac{\hat p}{M}t$$
where M is the mass of the device
Momentum isn't defined that way in QM.
12 hours later…
3:27 PM
@ACuriousMind Haha, classic
Let me reproduce a nice quote from one of my problem sets in MQM
@Qmechanic @Danu What is the "length" of a curve in spacetime that goes from timelike to spacelike?
What do you even mean by that
what do you mean by a curve
I don't know.
0celo7: "@MBN [An arbitrary curve can ... switch from timelike to spacelike.] True." -- So: Do we agree that the "Wikipedia prescription: the sign in the square root is chosen once for a given curve" does not provide a general and satisfactory definition of "arc length"? Then I'd be surprised/shocked if others had not arrived at this conclusion before. Thus I ask: Is there an established name and notation for the particular "solution to the problem" I described? (Else let's use what I made up.) — user12262 6 mins ago
"As a rigorous alternative of the (frequently but not convincingly) in-
voked argument of the uncertainty relation to infer the existence of a
nonvanishing zero-point energy for H, show (without solving explicitly
the Schr¨odinger equation) that the energy of the system is bounded be-
low by a positive constant"
Well that's important
usually a curve would be a map $\gamma: I\subset \mathbb{R}\to M$ with $\gamma(0)=A$ and $\gamma(1)=B$ for instance, if it's a curve between two spacetime events $A$ and $B$
It is obvious that such a thing does not 'change'
@ACuriousMind @Danu I can imagine Shankar waving his hands around "Could there be a zero-point energy? Is such a thing even possible? Yes it is."
@Danu I know what a curve is...
3:32 PM
The only thing I could imagine is a family of curves $\gamma_\lambda$ between $A_\lambda$ and $B_\lambda$ such that for certain $\lambda\in I$ the curve is timelike while, for other $\lambda$, it is spacelike
But there's nothing stopping it from crossing the lightcone
(Assuming it is not physical.)
@0celo7 You appear to be confused nonetheless
look, a curve is fixed
Q: Given the Wikipedia notion of "arc length", how is its manifestly real "signed variant" to be called and denoted?

user12262I am dissatisfied with the presentation (not to say "definition") of "arc length", in its "Generalization to (pseudo-)Riemannian manifolds", as given in Wikipedia. (Who isn't?. But I'll sketch it here as a starting point anyways.) Namely: [arc] length of curve $\gamma$ as $$\ell[~\gamma~] :...

He probably confused me. @ACuriousMind mind warned me about this one.
Perhaps he means a curve that is in certain parts spacelike and in others timelik
That's what I just said...
3:34 PM
I wouldn't say that the curve is changing then though
It changes from timelike to spacelike at some spacetime point.
That's not changing imo
it's more like certain sections of it are spacelike/timelike
@Danu We have different definitions of "change".
If it changes from timelike to spacelike, it obviously changes...
this question
okay let's not be rude
@0celo7 That's abusing the word 'change'
I'm not being rude!
Lol how
3:36 PM
no I was lol
Look the curve is a fixed thing
it does not change
I agree.
Its properties change.
The only thing that changes is the parameter as one moves along the curve
No they don't either, at all
And the tangent vector.
The properties are not the same everywhere. They don't change
The properties are a function of the parameter.
3:37 PM
this is imprecise
and leads to confusion as in this case
The properties of the curve are always completely known and fixed. This precludes proper usage of the word 'change'
No. There must be some language barrier.
Obviously, as one varies the parameter within $I$, the domain of definition, one gets to different parts of the curve where its tangent vector may be either space- or timelike
This is not the curve 'changing', it's just the curve not being boring :P
The sign is just there for the signature
Yes, but what happens if part of the curve is spacelike and part is timelike?
@Danu I explained that in my answer.
Your answer is fine
@0celo7 What about it?
How do we measure the length?
Write two integrals? One for each part?
3:44 PM
The usual definition holds for any path
@Danu This needs to be resolved. Let $\gamma(t):[0,1]\rightarrow M$ be a curve. For $t\in[0,\tfrac{1}{2})$, the tangent vector is timelike. For $t\in(\tfrac{1}{2},1]$ the tangent vector is spacelike. It is perfectly reasonable (English-wise) to say that the curve changes from timelike to spacelike at curve parameter $t=\frac{1}{2}$.
@Danu But $\sqrt{-g(\dot\gamma,\dot\gamma)}$ is imaginary for spacelike curves.
I think that's inaccurate use of language, but I understand what you're saying, yes
@Danu What is inaccurate about it?
Change is defined as becoming different.
I think it's more accurate to say that the properties of the curve at different points are generally not equal
@Danu You just defined change!!!
3:48 PM
Yeah, that's exactly the problem, it doesn't become anything. It's a curve, it's already defined, fixed.
You're just varying the parameter along the curve
You're not changing anything about the curve
As you move along the curve, the properties at your current position are different than they used to be at your past position.
But whatever, I can understand you just fine
that's not a good way to put it
I think you see my point, let's leave it at that
This is why space is 3d and everyone needs to treat time as slices of 3d space and not manifolds :D
I think the reason why this issue is typically not discussed in GR books is because one typically only discusses geodesics
@KyleKanos You numerical people...
3:50 PM
which don't do this type of stuff
@KyleKanos <3 hahahahaha
@Danu: BTW I cleaned up my end of the conversation from yesterday. don't think it's necessary to keep that around :/
@KyleKanos Okay, thanks for letting me know
Shall I leave the chat link?
If you want to. I don't think it's needed
lucky buy much
"It's kind of hard to fathom spending that kind of money on a sweater, but these are the times we live in," Vince Lombardi Jr., Vince's son, told the Asheville Citizen-Times earlier this week. "Whoever gets it I hope treasures it."
@KyleKanos I agree
@0celo7 anyways, in things like 'the distance between two points' these things do not happen
that's the take-home message
because the generalization of a straight line is of course a geodesic
So the question is not well-defined is what you're saying?
3:57 PM
I'm saying you can have curves that are partially time- and partially spacelike
but they will not represent distances between points in the manifold
@Danu OP asked how to define the arc length of such a curve.
Not distances between points on the manifold.
I'm not sure if it can be properly done
I mean, it's clear that piecewise computation should work, but it will give strange results
But maybe that's not a problem
I'm just thinking whether it's possible to get some kind of pathological situation where you cannot do it piecewise
Idk, some uncountably infinitely-many-times-switching curve
whatever, can't come up with anything on the fly :P
4:15 PM
This is a comment for the many-worlds' lovers. I deleted my answer because it won't help, and I am sick with this. (see continuation)
@Danu Hehe..."frequently but not convincingly" perfectly describes my feelings about these arguments :D
How does one determine the eigenvalues of a differential operator, i.e. the Laplacian? Zeidler just states that the eigenvalues of $\Delta$ on the unit circle are $\lambda_n=n^2$ where $n=0,1,2,...$
The collapse cannot be solved by many worlds, because it is not known what causes it. It is not sure that the decoherence at the contact with the macroscopic apparatus, produces the collapse - see entanglements where we have more than 1 apparatus, and we can't even say at which time are the worlds generated. But it won't help, because who wants those worlds at any price would argue endlessly, and invent new and new ad-hoc arguments. So, pleasant journey in other worlds.
@Sofia The fellow you argued with on that answer does not visit chat
@ACuriousMind my dear one, probably you are right. I placed my comment here because many people visit here, just for being sure.
@ACuriousMind I placed comments also at the respective site. It's on my tongue to say to all those science fictioners, "learn some physics" (the answer that von Neumann gave John Nash when the latter came with some QM proposals).
4:28 PM
@Sofia: While I am not defending (or attacking) MWI, your phrasing is a bit weird - MWI denies that collapse happens, but instead has only decoherence, so you attacking MWI for not explaining collapse sounds strange.
I think your argument is one that is commonly brought against MWI, phrased differently - the mechanism of creating worlds is not explained, many inaccessible but existing worlds are wasteful by Occam's razor, and how "we" end up in any particular world is similarily mysterious at first.
@ACuriousMind I'll answer you later. I jumped from my chair so angry I grew, and I have to calm down.
I am now picturing Sofia as She-Hulk (though she was a permanent green Hulk & not transformable like her cousin Bruce Banner)
@ACuriousMind Ah, yes! But when can be created that worlds? If we have two entangled particles (the photon/spin singlet), three entangled (GHZ), when do the worlds appear? And how can we get entangled worlds? Two, three, four, as many as we wish, entangled worlds. What a splendor!
4:44 PM
Yeah, that phrasing is better. Though I must say, of all things I get upset about, quantum interpretations are not one of them
@KyleKanos Aaaa! She was a lawyer. I like it. Thanks!
@ACuriousMind I wanted to tell you but I changed my mind in the last moment. After our long talk a couple of days ago (it touched mainly the collapse) I somehow began to hope that Bohm's interpretation would triumph. I believe that there is some truth in it. It seems to me that the thing can be checked experimentally, but I can't begin to work on that proposal for the moment. And I will need Alain Aspect's help. Hmmm! I have a good friend in France, but she is a biophysicist, not QM.
@KyleKanos and @ACuriousMind weren't you who told me about Lutheranism? What was the 1st name of Luther (the German one)?
5:01 PM
@Sofia Martin
@Sofia Martin Luther
Not to be confused with Martin Luther King Jr
It is confusing, not matter what you do
There are a few differences
Like race/ethnicity, language of choice, century of life
Sure, but two historical figures where one's name is a subset of the other's name is still going to confuse people.
I think the Dalai Lama is more confusing. Because there's been like 14 of them with the same name
At least with the Papacy, each has had a different name (including the Roman numeral following repeated names)
5:06 PM
@KyleKanos I think that the Dalai Lama is supposed to be always the same person, just reincarnated
So it's confusing for everyone else, but inside the system, it makes perfect sense
This is also true
(the reincarnation aspect, I don't think it's that confusing)
Unrelated: Could one of the experimental physicists take a look at this question and find out whether it is on-topic and/or has enough information to be answered?
Having done some (minor) experimental work in undergrad (working with Raman spectroscopy), it does appear on topic. Whether it has enough information to be answered, I cannot say.
@ACuriousMind , @KyleKanos reincarnated, yes, they believe in this. Did you see the movie "7 years in Tibet" (with Brad Pitt)?
I have not seen that movie @Sofia
5:20 PM
7yrs, great movie, based on real story :)
there is another movie that covers that topic, "little buddha"
keanu reeves/ bertolucci director.
@vzn I saw "Little Buddha", very beautiful. I like to learn about traditions, religions, culture of different nations. It teaches a lot of interesting things.
sof re extending bohm, try looking into the recent work of Bush cited in my last question, great stuff. think it pts the way fwd, very promising.
@ACuriousMind Is there a chemistry site in SE?
@Sofia there is
@KyleKanos can we migrate the question to there?
5:25 PM
A full list of StackExchange sites can be found here: stackexchange.com/sites#questionsperday
@Sofia You have to do Moderator Attention flagging to do so, but yes you can
What question do you want to migrate?
@KyleKanos the one, the Curious Mind asked about. Just a bit, I'll tell you the site.
The one about Xray diffraction & mobility?
@KyleKanos it's this.
I'm not convinced that an experimental physicist can't answer this
Mobility is a physics phenomenon in semiconductors (i.e., solid state physics)
@KyleKanos Are you softened by his "kind regards"? (I am joking.)
@KyleKanos Aaaa! I see. Well, but do we have solid-physics experts here?
5:30 PM
I am not, but I see no reason why this would be sent over to Chemistry.SE
@KyleKanos the question is whether we can help him.
I know. But I do not believe that Chemistry is the right place for that question
@KyleKanos I didn't see in our site many solid-state questions.
@KyleKanos I understand.
And over 600 questions with the tag
So there are no shortage of solid state questions
@KyleKanos what you say! I probably didn't pay attention.
@KyleKanos anyway, I didn't vote for migration, or homework, or so.
@KyleKanos let's hope that he will find an answer.
5:34 PM
I should hope not on a VTC for homework!
@KyleKanos I placed no vote, I 1st asked you.
@vzn can you tell me again the address of the post you indicated about Bohm?
5:48 PM
@ACuriousMind The German is strong in this one!
@vzn Thanks a lot. Very interesting indeed. I understand that it illustrates some simulation of Bohm's mechanics. Great! I'll read it attentively.
@sofia :) glad you like it, its way cool stuff, very cutting edge, so far not widely known, some wont like it, others will, think its defn the birth of an entirely new paradigm answering decades old questions in a dramatic, sound, near revolutionary way...
6:21 PM
@vzn I agree that the bouncing droplets are nice. But they can only reproduce single-particle quantum mechanics
Multi-particle quantum mechanics is where all the truly difficult conceptual issues arise.
(In my opinion)
So I'm definitely waiting to see what they can do with multiple droplets. But note that there is no way that they can reproduce entangled statistics with two droplets sharing the same fluid. This is already ruled out by Bell's theorem.
@Mark fully concede its a very nascent/ embryonic theory at this pt. as any serious student of sci history is aware, theories do not arrive on the doorstep full-fledged. think it will take literally decades to work out the specifics. agree these are near "toy" theories at this point. but intuition plays a role. the near eerie, uncanny explanatory power cannot be denied by anyone who looks at them closely. it seems a general theoretical answer to the notorious "spooky action at a distance..."
@vzn No, that is exactly my point. It cannot be an explanation for "spooky action at a distance".
It just can't
This was ruled out by Bell over 30 years ago
MM everyone has a lot of instincts on this. some authors have worked out the basics of the objections.
bell had a lot of great insight. but lets face its now decades old.
But it seems to me that experiments which falsify the hydrodynamic explanation have already been performed fairly convincingly and conclusively.
am personally a huge "fan" of bell.
the experiments have some narrow loopholes.
6:29 PM
@vzn It is a mathematical theorem. Forget about Bell the person. Unless you believe that mathematics goes mouldy over time, then I do not understand what you mean.
these "small openings" are enough to drive an entirely new theory through.
agreed it is mathematics. there is new mathematics that shows a way.
@vzn Ah, so you're going for the loopholes. OK I see what you mean.
the loopholes are quite subtle but exist.
Q: What are the main issues that are preventing a human mission to Mars?

SuperCiociaIs it just because it'd be very expensive? Or are there serious problems that need to be dealt with, studied and solved? If so, what are they?

Off-topic and migrate to Space Exploration?
but its interesting to note that all new theories can regarded as walking through "small/ subtle loopholes" (in prior theories). taking a very kuhnian pov.
bells analysis is "correct" in the context of its assertions.
eg the difference between einsteinian relativity & newtonian physics only exists in "extreme edge cases".
6:32 PM
Right, but those are all the assertions for a nice theory with out any weirdness. If you relax them then you might not have spooky action, but you have something else equally philosophically repugnant.
@Qmechanic I would say definitely off-topic.
so a lot of initial/ healthy skepticism is entirely warranted. do not deny that.
agreed the theory is esp going to be difficult to advance past the simple cases already studied. (if possible) it will require amazing math insight eg on the level of what von neumann did for axiomatizing QM. possibly even more.
Yeah. But the point is, I'm not even really excited about this as an explanation, because it will make things even more confusing if it is true. It doesn't really "resolve" the philosophical issues, they are always going to be there. Obviously if there were experimental evidence I would be enormously excited. But also daunted by the prospect of a theory that is even more confusing than QM.
@vzn That is not a "Kuhnian" point of view at all. Kuhn regarded Newtonian and Einsteinian physics as incommensurate. Although Newtonian physics is the (mathematical) limit of general and special relativity, their concepts of space and time are remarkably different.
QM is quite confusing to begin with. maybe a lot of that confusion is our conceptual model. ie "interpretations".
I guess I'm just trying to say, don't get your hopes up about a general theoretical answer to the notorious "spooky action at a distance..."
6:35 PM
am not a total expert on Kuhn but afaik newtonian to einsteinian physics is a classic Kuhnian shift.
@vzn Yes. What I am saying is that this new theory must be at least as confusing as QM. This was the insight of Bell.
MM my hopes are (justifiably) quite high :) but also have to be very patient on the very ambitious long term goals. its a research program, not a full fledged theory yet.
bell/ bohm work can be seen as valuable stepping stones.
@vzn Yes, he regarded them as incommensurate. He certainly would not have thought that they were only different in extreme edge cases. They have incommensurate notions of space, time and simultaneity.
Kuhn was not an expert on physics :)
"incommensurate" is not really a scientific term. it sounds like a philosophical term.
physicists will naturally understand my "edge case" assertions. its a widely accepted/ acknowledged concept in physics.
@vzn I guess @innisfree is saying that your viewpoint should not be attributed to Kuhn.
Since he would not agree, whether or not he was right or understood physics.
6:39 PM
kuhn is not alive to join our conversation :|
same with bell/ bohm.
From an operationalist viewpoint, however, you are correct about the "loophole" interpretation of scientific progress. But then there is also often an associated conceptual shift.
afaik nobody has made the "official list" of kuhnian shifts, not even kuhn himself.
its all a shift. conceptual etc., it can take decades for these shifts to fully play out. they are like massive waves.
let me dig up a ref for you MM, you may not like it, but it attempts to directly address the spooky action at distance issue "inherent" in fluid mechanics.
am just a messenger here guys so ofc feel free to shoot indiscriminately :p
my feeling is that simulations have massive potential to highly advance this area, but nobody else has noticed/ realized that yet.
Yeah please do. I generally am interested in foundational issues, I am sure I will like it.
ok cool.
I am just confused to death; it seems too hard to make progress without experimental input, so I'd rather spend my time thinking about physical models and systems which probably do exist!
6:46 PM
what happened to that natural skepticism? :p
Like $\neq$ believe
there is both awesome experimental/ theoretical work in this area, agreed it will not advance without a masterful fusion.
like all big/ TRUE theories.
I mean quantum experiments!
Just demonstrating that a macroscopic hydrodynamic analogue can reproduce Bell correlations given some loopholes does not constitute any progress at all./
You have to actually do an experiment with an electron
6:48 PM
"frustation" is a natural part of the research process early on. think of the frustration of the QM pioneers.
same with atomic model. etc.
Yeah but they could do experiments
In fact, lots of the experiments had already been done.
e.g. spectral series
black-body etc.
can expand on their basic explanation sometime. but arguably spooky action at a distance is a basic feature of classical wave systems combined with a probabilistic measuring rule of wave amplitude (borns rule).
no question its counterintuitive to current understandings.
lets note that almost no bell experiments have been done with electrons/ particles. its almost all photons.
admittedly there are some rare particle experiments.
@vzn I'll take care that this article be known to my acquaintances, and I'll ask them to handle it further. It is an important article and has to be well studied. I'll stay with it, probably on the week-end.
@vzn again, thank you a lot.
:) thx guys its all foreign/ alien/ terra incognita right now, its a long term project, rome wasnt built in a day :)
encourage/ invite further discussion in another chat room.
intermittent contributions just fine.
you gentlemen/ lady are all super sharp & its a pleasure to converse on these arcane/ abstract topics with those who have serious bkg/ interest etc.
@vzn I thought that Kuhn was an expert on physics. For example his book on the early history of quantum mechanics is somewhat technical, too.
6:57 PM
imho kuhn is brilliant but more coming from humanities than science. hes an expert science historian which is quite different than a scientist.... he has been seriously challenged by some scientists, imho quite credibly so.
for example, this is a subtle but key point, kuhn did not seem to believe in "true" theories. or one theory as being "more accurate" or a "truer picture" than another.
he didnt seem to acknowledge how new theories "mesh perfectly" in some sense with prior ones.
I know he's mostly known for his more philosophical work, but now that I checked, he apparently did get a PhD in physics from Harvard.
wow! way cool! news to me learn something new everyday :)
kuhnian theories are just another paradigm, subject to revisions/ clarifications :)
@vzn he was a philosopher and historian of science. i don't think you've grasped his ideas. he understood that e.g. that the mathematical low-energy limit of general relativity is newtonian gravity. he argued that they didn't "mesh" because they didn't share commensurable concepts or vocabulary. a newtonian and an einsteinian don't, for example, have a shared concept of space or time.r
am not an expert on the details of his philosophy...
ofc they mesh.
physicists are neither newtonian or einsteinian, they are both. after the paradigm shift. during the paradigm shift, there is a conflict. but the conflict is eventually resolved as no actual conflict.
they don't, though, do they? to a newtonian space is an "arena" in which things happen. in relativity, it's a rather different picture, isn't it?
7:06 PM
because both pictures are "correct" based on the context. what paradigm shifts do is clarify contexts so to speak.
How big a difference does gpa make in grad school applications? If I have a cgpa of about 3.83-3.85 (my current cgpa, on a 4.0 scale), will I stand a significantly lower chance of getting accepted than someone with a 3.9-ish cgpa?
agreed that some of my own statements about kuhn are my own embellishments/ extrapolations/ interpretations. am not a literalist in that way.
I'm kind of seriously freaking out about my gpa so I was wondering.
AH there is a heisenberg uncertainty measurement there :p
AH try this ref for some analysis/ insight
in toy models of QM, yesterday, by vzn
its called the "excellent sheep" critique by Deresiewicz
I see, thanks
7:11 PM
kuhn probably didn't believe in "true" theories (does any philosophy of science?), but he does discuss theory confirmation towards the end of structures. he did believe it possible that one theory could be said to be more probable than another (though he thought it was problematic in practice).

i'm surprised you've chosen that criticism. e.g. popper certainly didn't believe in true theories or that one theory could be said to be "truer" than another.
@MarkMitchison : Could you then please do me a favor and vote-to-close-as-off-topic, so that it enters the review system?
physicists are keenly interested in the truths of nature. scientists in the same way. dont know another word for it. its a concept that humanities critics seem surprisingly wobbly/ weak on.
the universe has (eternal) truths associated with it. that is a fundamental precept of science/ scientific method etc.
whose scientific method! there is no neutral, null method. can't you see that you're invoking particular ideas about the philosophy of science just by saying that?
are we now questioning the scientific method in a physics room no less? not sure can continue this conversation :p (irony by you?)
there is no universally agreed upon scientific method. the dominant method of science - popper's falsificationism - doesn't meet your desiderata. it has no concept of "eternal truths" or a single true theory, or even the idea that one theory is "truer" than another. it rejects theory confirmation.
7:19 PM
← see kuhnian shifts even in eg math. probably unconventional. not sure exactly how kuhn regarded math.
uh, not following/ familiar how popperian falsification "rejects theory confirmation". this is getting a bit abstract/ philosophical for me...
popper wanted to build a philosophy of science on deductive reasoning only. theories could be rejected, but never confirmed or even considered "probable" or likely to be true.
the scientific method hinges on repeatability/ reproducability which inherently invokes something like "eternal truths" (btw a redundant phrase)
have heard the basics of popper but think he (like kuhn) was "off" in some ways.
popper/ kuhn ideas mostly seem to mesh. to me popperian falsifiability is a key component of paradigm shifts.
you must be joking?
(skimming popper wikipedia entry) to me its a bit of a philosophical technicality to say that theories cant be proven "true".
"there is no universally agreed on scientific method"... this is philosophical hairsplitting. a basic method has existed for thousands of years. there is some experimental science by the greeks although admittedly they were weak on "scientific method" from a philosophical pov.
no, it is not a technicality. it was one of popper's important insights. out of interest, what exactly do you mean when you say "the scientific method"?
7:29 PM
ofc popper might not be familiar with it, apparently (unlike Kuhn phd physics) and maybe like other humanities "science critics" never having personally engaged with it, only hearing 2ndhand accounts :p
anyway my arguments are reflected by other eminent thinkers.
might dig up a citation sometime.
popper wasn't particularly concerned by the practice of science, you are right. he wanted to build a logically robust, normative idea of science. kuhn, on the other hand, wanted to understand and describe how science was practised.
anyway, what exactly do you mean when you say "the scientific method"?
scientific method dictionary.com
(this reminds me from long ago when a defense attorney asked me what my definition of "murder" is. some other story...) :p
did you realize its in the dictionary? :p
can it include inductive reasoning?
anyway re "other eminent thinkers" try pinker vs the humanists, he makes a better case on this that me, admit some affinity for his "arguments" (and it is indeed an "argument" going on)
so are you now trying to trap me like a modern socrates? admittedly induction is a massive problem to philosophy but used every day in science :)
the dominant idea about science - and what most people consider the scientific method - does not use induction. if it was a bear trap, you are in it.
7:42 PM
ouch, aieee
speaking of "problem of induction", you might be interested in field of automated thm proving
7:57 PM
spking of "caught in bear traps," seems, philosophers sometimes twist themselves into intellectual knots/ pretzels....
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