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@0celo7 Pretty
 
:(
 
1:06 AM
@DanielSank Don't leave out "paradox" and "twin".
 
@DanielSank Question: does the uncertainty principle respect the twin paradox?
 
1:23 AM
@0celo7 I want to edit that so bad.
 
@DanielSank Can an uncertainty principle-dark matter reaction be responsible for how the EM drive works?
 
@0celo7 It hurts.
 
@DanielSank How is the uncertainty principle manifested in string theory?
 
 
1 hour later…
2:47 AM
@NeuroFuzzy Sadly quality is not measured by votes and fools are fooled by pretty pictures. I still maintain that your answer does not even begin to address OPs concerns.
@KyleOman Linux Mint 17 is pretty stable & based on Ubuntu, so you get all the benefits & none of the kinks
 
yesterday, by Kyle Kanos
> Our test campaign can not confirm or refute the claims of the EMDrive but intends to independently assess possible side-effects in the measurements methods used so far
Look around that message for a brief discussion of that "news"
Perhaps ignore @0celo7's talk of watermelons :P
 
vzn
what about:
> Our measurements reveal thrusts as expected from previous claims after carefully studying thermal and electromagnetic interferences.
 
@vzn They, like others beforehand, found that even after shutting off the power supply, the thrust continued.
 
vzn
> Claims his findings could revolutionise space travel with increased speed (dailymail)
 
That's a key sign of a false positive
 
vzn
3:10 AM
have you read the whole article? apparently its behind a paywall :(
@KyleKanos so they are asserting its an "artifact"? some kind of measurement error? this is hard to follow
 
Well (a) it's a conference proceeding and (b) it's not needed because it is bunk work
 
vzn
think that this is a circuitous way to attempt to prove a "false positive"...
are you saying they think they "replicated a false positive"? (whatever that means)
 
@vzn What it seems they're doing is ignoring that aspect as a systematic error and attributing some fantastic & unknown mechanism to producing an otherwise impossible thrust
@vzn That is precisely what they've done
 
vzn
do you think they are making invalid claims or not?
 
Completely invalid claims
 
vzn
3:13 AM
strange, building invalid claims on invalid claims, reminds me of cold fusion somewhat...
 
@ACuriousMind lol what
 
vzn
supposedly the original studies are done by NASA though?
 
my roommate just asked me if I play LoL
 
The researchers from Dresden don't make any strong claims - they just say they've measured the same "thrust", but can not exclude e.g. feedback from the power supply lines or other causes for it.
 
@vzn IMO, it's funding hype. Claim some preposterous thing is real, get boat loads of public interest and the financial support follows (same thing happened with global warming research)
 
vzn
3:15 AM
but surely they attempted to/ went to significant effort to isolate spurious causes.
 
@vzn I thought the original was Chinese, but some guys associated with NASA made a claim about it working too.
 
@0celo7 I linked a chat massage which goes to Kyle talking about the EM drive interspersed with you discussing, among other things, watermelons. :P
 
@KyleKanos was visiting someone in his office
 
@0celo7 Nice
@vzn Meh, claim you tried hard but ignore the fact that you either know what happened or didn't actually try, then collect money regardless
 
3:16 AM
@0celo7 Your roommate? Are you at college already?
 
@ACuriousMind ::looks around::
no
there's a magical thing called telephone
 
And email..don't forget that magical thing
 
Alright, stupid question :D
 
@ACuriousMind No such thing as a stupid question
 
vzn
ok, found a thorough debunking link posted by Kyle, but it seems like there would be at least mild incentive to definitively disprove these false claims via some setup...
 
3:22 AM
@KyleKanos wrong
anything with "question, uncertainty principle, twin paradox, dark energy, dark matter, EM drive"
 
@vzn So basically, someone who does not have a vested interest in funding from EMDrive fanaticism would need to test it and show that it's bunk
 
@ACuriousMind why are you up
 
@0celo7 Actually, those are legitimate questions, we just see them far too often
 
Heisenberg should have been shot for developing his principle...that whole Nazi business is forgivable
 
@0celo7 Why should I not?
 
3:31 AM
::checks Steam::
omg
ARE YOU READING STRAUMANN
 
lol, no, I'm reading lattice stuff for the exam on Friday
 
huh my roommate likes Skyrim. I think this will be alright.
 
@KyleKanos ~shrug~ it's a clear demonstration of the phenomenon and gives a good reference. I'm not spending much time on a 0 vote 0 answer 1 sentence question.
 
@ACuriousMind Straumann does salad stuff
Skyrim mod fails have me depressed
 
@0celo7 But not lattice QFT stuff, does he?
 
3:33 AM
@ACuriousMind uh, you'll have to read the book for that
Might be in there somewhere
 
@NeuroFuzzy It's a clear demonstration of light echoes. Sadly, the question was not actually about light echoes. At best, it's a so-so "answer"
Actually, it's a so-so demonstration of LEs. It shows a single image and provides no information as to what it is or how/why it works, only a reference
 
@KyleKanos So what IS it about? A beam, not a pulse of a light? That is, "why is fog grey"?
 
It's asking if light travelling through a cloud, perpendicular to LOS, is visible
Light echoes require specific geometries to be matched, so it's actually a somewhat rare event
We see clouds adjacent to stars that are being illuminated by the star (perpendicular fashion), so OP wants to know how we can see those clouds
Your answer says, "I'm going to ignore what you said, show you a flashy image, and gain 330 rep in the process"
More a statement of the lack of knowledge of the general public, since they're not knowledgeable enough to know what OP is asking and how you've entirely avoided answering it.
 
That seems like it's assuming way too much.
Ray emitted from supernova. Ray scattered off of cloud. Ray reaches a telescope providing an at-later-date record of where the supernova light had reached. Ray of light detected while passing through the cloud. That's what the OP's question was about.
 
Who says it's a SN?
He wants to know why light shined through a cloud is not visible
That's is precisely analogous to a star brightening an adjacent cloud
 
3:45 AM
...and is also demonstrated by a supernova. I really don't see what the problem is.
 
And dude has +19/-1 on the question, so not even sure we you're mentioning the state "0 vote 0 answer" when you answered it
@NeuroFuzzy The problem is you've not actually answered OPs concerns
 
I was*
We're arguing over a slightly different interpretation of the question and I don't think that's worth either of our times...
 
FWIW, this is answer actually addresses OPs concerns:
5
A: Why can't we see light travelling from point A to B?

WBTIf some of the light is reflected off the dust at such an angle that it is diverted to reach the observer, the observer will see that light. However, those specific photons reaching the observer will not reach B (unless they are reflected there by the observer). Similarly, unless the observer is...

 
FWIW, I completely agree with this comment:
I'm not sure whether this is a question about light echoes, or a fundamental misunderstanding of what it means to see something. — Lightness Races in Orbit 18 hours ago
...and I'm completely unsure why that question has gathered so many upvotes.
 
@ACuriousMind < this
 
3:48 AM
@ACuriousMind Fancy animations + HNQ effect
It's actually a tough question astronomy students may not understand correctly the first time they sit down to think about it
 
lol, Oblivion dialogue
 
The phrase "to see the light while it travels" in the question lets me suspect that OP doesn't actually understand what "seeing" is, and that the fact that there are light echos and whatnot in astronomy is actually wholly unrelated to what OP wanted to ask, regardless of how well they are explained or not.
 
@KyleKanos upvoted. If I can give a great relevant reference which plausibly answers the question, or let a question sink into oblivion, I'll do the former!
 
"Anvil is in an uproar, the chapel was attacked." "NO!!!" "Sure." "Bye."
 
@0celo7 What, you expect people to retain their emotional state for longer than a few seconds?
 
3:53 AM
"By what right do you disturb me?"
I can literally delete you from the game
 
 
4 hours later…
8:05 AM
Hello
 
user54412
@Danu Hey now.
 
user54412
(Actually it's kinda true, which makes me sad)
 
user54412
Also, cosmology as done by all the working cosmologists I know is barely more GR than Minkowski space -- often it's purely Newtonian in fact :P
 
Well you don't use GR when it's not necessary
 
8:50 AM
@ChrisWhite Haha, yup... I like GR so much, I hate that nobody really needs it ;)
 
9:33 AM
@obe : the physics isn't outdated. Don't be so quick to dismiss Einstein out of hand. Read the digital papers instead. Then when some textbook paints a totally different picture whilst appealing to Einstein's authority, put your thinking cap on.
 
9:44 AM
@JohnDuffield you see that's the whole problem, educators and textbook writers do all the thinking :)
and they justify it by claiming that it makes learning "easier."
 
10:33 AM
@skill patrol : there does seem to be some kind of issue wherein textbook authors somehow "stray from the science" and students never read the original material. Then they grow up and write textbooks.
 
@JohnDuffield Indeed, and the "thinking cap" gets lost along the way.
The "original material" is distilled and refined to the point that even the original author can't recognise it @JohnDuffield as Einstein once said to Lorentz about special relativity.
 
 
1 hour later…
11:46 AM
bluh
Doing Jacobi elliptic function
What have I done to deserve this
 
-4
Q: Is momentum an invariant?

user12262Is the value of momentum an invariant?, specificly for instance the momentum value $\mathbf p_{\text{lab}}[~\Lambda^0~]$ of a $\Lambda^0$ baryon (drifting from the (actual) interaction point of a collider experiment towards the beam pipe wall) with respect to suitable(1) constituents of the "lab"...

This is so ridiculous
user37496: "If I measure the speed of a particle in the lab and then write down in my notebook the value" ... as real-number multiple of $c$ ... "an observer in a different inertial frame reads [...] the same" -- Correct. Real numbers are presumed unambiguous; they can be copied; +1. "(although [...])" -- Their graph structure (or topology) should remain distinctive enough. "context that led you" -- Foremost this: "speed itself is a coordinate system dependent concept"; then that. — user12262 2 days ago
He must just be trolling. The topology of $\mathbb{R}$? lol!
Or this is just a really poor confused person :(
 
The topology of R can be several things!
Physicists just tend to use the canonical topology
 
(that, too, is besides the point... lol)
 
assume they are confused until proven otherwise
 
Have you seen their other posts?
 
12:01 PM
not yet
 
Enjoy the (extremely boring, pedantic) ride
@skillpatrol I don't think Einstein had a particularly good understanding of GR by today's standards.
 
Well it was a pretty new thing
He died when GR got really interesting
 
He also thought he'd proven gravitational waves don't exist in 1936.
 
Another data point for "physicists don't know what a proof is".
 
Also he wrote a paper on wormholes
The thing Duffield hates so much
He wrote the first paper on wormholes, even, I believe
Hey @ACuriousMind
 
12:10 PM
@ACuriousMind He probably was not naive enough to claim a rigorous mathematical proof :P But a physics-proof is good enough... If it's correct!
 
are the associated bundles of the standard model just like
C^4
Or is it C^2
Or something else
Also is that the so called Dirac Bundle
 
How is C^2 a bundle?
Do you mean are the vector spaces C^2 or C^4?
 
Well the fiber
 
Well, for Dirac fermions, it's C^4, and for Weyl fermion/handed particles, it's C^2
 
Thanks
I was wondering because books are very shy about mentionning C^4 for spinors
 
12:12 PM
But since the Weyl parts of massive fermions don't decouple, it's a bit difficult to decide what one should "really" use.
 
But for the weak interaction it's not applied to both, no?
 
Yeah, the weak interaction acts only on the left-handed part
 
Would the bundle be something like (M, C^4, pi, SL(2,C) x a bunch of gauge groups)
For instance would a quark be (M, C^4, pi, SL(2,C) x SU(3) x SU(2) x U(1) )
 
No, I think not
 
Hm
What would it be
 
12:14 PM
why do you have $\pi$ in there?
 
The $\mathrm{SU}(2)$ of the weak interaction does not act on the two d.o.f. of the Weyl fermion
 
The projection
 
hahaha okay
I've never seen anyone write out the projection explicitly
 
(M, C^2, pi, SL(2,C) x SU(3) x SU(2) x U(1) ) then maybe?
Although left and right are still coupled
 
@Slereah No, the space the combined gauge group acts on is far larger than C^2
 
12:15 PM
Hm
I dunno
 
Although the Weyl fermion may be a two-component vector, these are not the two components the weak interaction acts on
 
I've seen a pretty good book on gauge theory topology on Physics Overflow
I should get it
 
Link?
 
Btw, do you read french? If so, I'd recommend reading Grothendieck's memoir
 
12:16 PM
Every component of the Weyl fermion is, in turn, a C^2 vector if it transforms in the fundamental of SU(2)
 
Nakahara is terrible :P I distrust anything that mentions it :P
 
Oh
What's a good one then
 
And if it transforms under various gauge groups, you get things like "It has components which are components which are components", if you want to write it out explicitly
 
I only have Steenrod on fiber bundle
 
(which I fear you want ;P)
 
12:17 PM
So.. you thought about getting Nakahara? ah lol
 
But it's just math
 
It's for physicists, that's why it sucks
Maybe you'll like it if you're not into pure math
Also note that Nakahara is available online legally IIRC
 
Well I want it for physics :p
I'll probably get a paper version if it's not $200
 
I think learning mathematics from physicists is a grave error
Learn it from the mathematicians, maybe talk with the physicists later to see their tricks :P
Just get volume 1 of Kobayashi & Nomizu hahaha
real shit :P
Anyways, you won't get anything like the Standard Model in there :P
 
Well as said, I got Steenrod already
"The Topology of fiber bundles"
 
12:21 PM
Steenrod is kinda old, isn't it?
...so is K&N, though
 
Steenrod from the Eilenberg-Steenrod axioms!
Yeah, that's kinda old
 
Steenrod from the times of Chern!
I'll have a look at it after I finish this Bredon book
(...after I finish this Vinberg book)
 
Is there any good recent book on all this fiber hulaballoo?
 
Do you read German?
 
I can, I just can't understand it
I once read a Greek-Latin version of Arithmetica, by Diophantes, despite reading neither languages
It was still somewhat informative
That is the nice thing about math
 
12:25 PM
Somehow, there are two books particularly focusing on this stuff which are supposed to be good, and they're both only available in German...
 
Kudos to Diophantes for using the first mathematical symbols
 
Helga Baum - Eichfeldtheorie is good
It goes up to the Yang-Mills equations I think
Furthermore I know of:
Sontz - Principal bundles (2 volumes)
Husemoller - Fibre bundles
^(looks really awesome too)
And I just found out I can complete my Bourbaki collection :D Springer books for free is the best thing that happened to me since... Not really, but it's pretty nice :P
 
Ugh Bourbaki
 
@Danu As far as i know, there is only one rigorous meaning of the word proof...and (sadly) physicists usually do not prove anything
 
I'd rather reread the Principia Mathematica than Bourbaki
 
12:38 PM
@Slereah It's like comparing peaches and cabbages...
 
@yuggib Peaches are good, cabbage is awful. I have no problem in comparing that ;)
 
Well yes
exactly
I mean Russell's Principia, not Newton's
 
@Danu I would have known that four years ago when I bought the entire bourbaki collection on paper...
 
@yuggib Hahaha, really? That's kind of a waste of money eh!
 
@Slereah yes I know ;-P
@Danu T__T
 
12:41 PM
Russell is still pretty awful really
My god that notation
He had that weird idea of foregoing parenthesis and use a weird dot system
 
Why do you think Bourbaki is so bad, @Slereah?
 
It is very dry
 
Do you think all mathematics books are very dry? Or just these?
 
Bourbaki in particular
 
@Slereah I do not agree... théorie des ensembles is a very nice book (even if it uses the Hilbert quantifier $\tau$ that is not very common nowadays)
and very clear
@ACuriousMind :-D they're also both (parts of) a vegetable
 
1:26 PM
Phew, did a big answer
I rarely do~
Hey ocelot
 
@ACuriousMind cabbage is awesome
 
can you make cabbage alcohol
 
@Slereah hey
Skyrim still broken
@Slereah probably
just stick a cabbage in a jar for a few few years, see what happens
 
"I have fermented cabbage to alcohol. The largest problem with cabbage is its very small amount of sugar and its reaking smell when cooked down to a higher sugar level. If it is boiled for a long time it can be concentrated to the point that makes it worth while. "
"The ending result was stilled in a pot still. I had to run it a couple of time to get the cabbage flavor down to a level I could tolerate. "
:D
 
@0celo7 get sauerkraut?
 
1:36 PM
@KyleKanos sauerkraut, on the other hand, is nasty
 
I disagree, it's delicious
 
demon!
 
Sauerkraut is a form of cabbage I can tolerate.
 
Sauerkraut is just about the worst part of German cuisine
 
You are quite a sour kraut
 
1:39 PM
and I have to clean the f key again
I know exactly where the goop is but I can't reach it
 
Just, hi!
 
Hello
 
@ACuriousMind Since you love indices so much, you should read Section 13.2 in Wald...the spinorial Riemann tensor has eight of them.
 
Oh god yes
It's the best section
Know what else has a lot of indices?
 
ur mum
 
1:42 PM
"Fields" by Warren
De Witt has a book chock full of 'em, too, I forget which
 
885 pages
wtf
people have too much time
 
It ain't bad
I love him because he writes out spinor indices
 
Probably started as lecture notes
 
A lot of books did
 
@ACuriousMind $$R_{AA'BB'CC'}{}^{DD'}=\Psi_{ABC}{}^D\bar\epsilon_{A'B'}\bar\epsilon_{C'}{}^{D'‌​}+\Phi_{A'B'C}{}^{D}\epsilon_{AB}\bar\epsilon_{C'}{}^{D'}+\Lambda (\epsilon_{AC}\epsilon_B{}^D+\epsilon_{BC}\epsilon_A{}^D)\bar\epsilon_{A'B'}\bar‌​{\epsilon}_{C'}{}^{D'}+\mathrm{c.c.}$$
 
1:49 PM
heheh
Good old spinor GR
 
@0celo7 Ew.
 
Tho it's not as awful as Penrose-Newman GR
 
@Slereah even Wald is like "fuck that, cf. their paper"
 
@0celo7 That is pretty ugly
 
That's a common thing
because fuck that
Pre-internet, that must have been pretty frustratin
Imagine having to go to the library and order all those papers everytime you found some bibliography
Just gotta wait a few weeks!
 
JiK
1:52 PM
Yeah but back then they also had things like job opportunities.
 
Tell me about it
Cold war was a good time to be a physicist
 
The sad state of affairs (NSFW, I don't know why she's even naked)
I need Skyrim halp
 
As this song informs you :
How nice to be a physicist in 1947,

To hold finance in less esteem than Molotov does Bevan,

To shun the importuning men with treasure who would lend it,

To think of money only when you wonder how to spend it
Research is long,

And time is short

Fill the shelves with new equipment,

Order it by carload shipment
heheh
The actual song
Toward the thesis drive the student,

Physics was his choice imprudent,
Too true ;w;
 
 
1 hour later…
3:14 PM
Wise words indeed, @yuggib ;)
 
Real world applications tend to have time dependant hamiltonians, thouh
unless you want to find the wavefunction of the universe
 
The problem in that sentence is "real world"
And who doesn't want to find the wavefunction of the universe?
Or, rather, the wavefunctional.
 
(also curved spacetime applications are not time independant!)
A functional is just a function!
 
Yes, the terminology is annoying.
 
(Rel A ∧ (A ∘ ◡A) ⊆ I )
Same thing
 
3:45 PM
but you don't measure it as non-zero, and the simple logic says half of zero is zero is a new low: rejecting/intentionally misrepresenting observations simply because it doesn't fit with ones expectations
 
@ACuriousMind @ACuriousMind $\mathrm{Real World Application}$ is an operator $R$ such that $R:\mathrm{GDP}\mapsto\mathrm{GDP}+\epsilon$ for some $\epsilon> 0$.
@ACuriousMind I don't; that would probably break something.
 
@0celo7 I think most of what I'll probably ever do lies in the $\epsilon\to 0$ regime ;)
@0celo7 That's no reason for a scientist to refrain from doing something.
 
@ACuriousMind Are engineers scientists?
 
@0celo7 Usually
 
3:54 PM
The experiment is who dies at the hand of the death ray
 
^^
Time to add LoZ music to Oblivion.
 
@Kyle Kanos : no it isn't a new low. I'm not misrepresenting observations. The coordinate speed of light is zero. Einstein would have called it the speed of light. Next time you see something moving faster than light be sure to tell the guys in Stockholm.
 
Er, the observations say v>0. You're saying v=0 because c=0 because you want it to
 
Coordinate speed of light is zero? Define coordinate speed.
 
4:11 PM
@0celo7 : no. Go and look it up. @Kyle Kanos : no, I'm saying c=0 because a black hole is black. The vertical light beam can't get out because at the EH the speed of light is zero. Please don't tell me you think it's can't get out because space is falling inwards.
 
I'm saying that the spin of a black hole was measured as being more than 0 so insisting it is zero is flat-out idiotic.
It's turning a blind eye to reality.
I don't care what you believe when it comes to theories, but when you start actively rejecting experiments/observations because it conflicts with your theory, I think you should refrain from calling yourself a scientist because that really isn't science
 
I don't understand what all this talk about coordinate speed is for. Light can't leave a black hole because no light-like geodesic starting at the EH points outward. This is a completely coordinate-free statement. That the coordinate speed in any particular coordinate system should carry any significance at all is not obvious.
 
So E=MC2, which means that energy is equal to mass times the square root of the speed of light. Is it really necessary to add the words when the equation says the same thing?
(even though the words are wrong)
 
4:29 PM
@ACuriousMind Correct.
@JohnDuffield By definition, a black hole is a region of the spacetime manifold which lies outside of the past of null infinity.
Coordinate speed has nothing to do with it.
 
Well if the spacetime is asymptotically flat
 
Yes
 
@ACuriousMind ;-) unluckily sometimes you cannot follow that advice...
 
I need a lantern mod for Oblivion
This game is way to dark
 
BTW, @0celo7, are you aware of Nehrim?
 
4:32 PM
wat is this
@ACuriousMind explain yourself
what is this
 
in before ocelot disappears for 10 months due to immersion in TES
 
@0celo7 The work of crazy Germans with too much time - they created an entirely new game in the engine of Oblivion
New landscape, new story, new experience system, new things...everything
 
Well those Germans!
 
But will they be able to replicate Oblivion's colossal disappointment, though
 
Well let me beat vanilla Oblivion first.
 
4:35 PM
@Slereah Nothing can come close to that :P
 
what's so bad about it
I'm playing it right now
 
It's not a bad game
But it pales in comparaison to Morrowind
 
If you played Morrowind, and expected a successor to that, then it just was not what you were looking for.
 
Morrowind is shit
I don't want to go on 3 minute walks
 
Damn kids
Back in my days we didn't need no fast travel!
 
4:38 PM
I don't mind that
 
Except in Fallout, Baldur's Gate and Arcanum
Of course
 
but fuck me the running speed is so god damn slow
 
you have a running skill tho
it gets better
 
I don't want it to get better
the game is maga boring
 
them's fighting words
 
4:40 PM
the only problem I have with Skyrim are the female models
and the other 50 things I modded
Morrowind on the other hand
the running speed needs to be fixed
 
I enjoyed fast travelling in TES3, but when I discovered that there's like a billion hidden caves, I stopped using it
 
there's fast travel in Morrowind?
@ACuriousMind is the game in German?
 
There's a caravan system of some sort
 
@0celo7 silk strider, mages guild teleporter, and some spells
 
You can go from city to city with them
 
4:42 PM
@0celo7 It's available in German and English
 
@ACuriousMind doesn't count
German games sound wrong
 
I do miss teleporation spells in Skyrim
Also levitation
 
mods
looks cool
@ACuriousMind do you have to disable all mods to do a total conversion?
 
@0celo7 Yes
I think their installer even tells you to provide a fresh install of the game or something like that.
 
hmm, Oblivion isn't heavily modded
Just a UI, script extender, face and body mods.
Skyrim, on the other hand...
My roommate wants me to show him how to mod Skyrim XD
 

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