The h Bar

0celóñe7

12:01 AM

these are allegedly the same gray

formatting is too hard

rob

@0celóñe7 Yeah, if you have two different oranges and two different grays no one is going to judge you for it.

0celóñe7

@rob the black is so close to the gray, that would be less noticeable than the light gray text

there's no good reason why it should be so light

I have to make some food though

Secret

12:15 AM

@DanielSank For that, I literally copy it line by line in the interpreter. That way, I get to chose which chunk of code to test

Still annoying to copy paste so many times though

Secret

0

Q: Help me to understand how time is relative!

I'm a bit confused about how time can be relative. Example: if a cosmic event happened that could be observed from earth, multiple times, because light from this event reached earth at different times because of timespace distortion due to a planets partial obstruction. Does it not just mean that...

spacetime

Kyle Kanos

1:55 AM

@ACuriousMind Thanks ACM. Outta curiosity, is it the same person who's been DV'ing me? Or are you unable to tell me or discern that?

Secret

2:06 AM

Expecting white dwarf merger soon

arxiv.org/abs/1708.05287

0celóñe7

soon?

like astrophysically soon?

Rumplestillskin

2:20 AM

Does any one have any experience with general relativity and incorporating non-gravitational forces in equations of motion?

Or even any idea on where to start?

Prathyush Poduval

@AHB Okay thanks!I hope google translate suffices for it :P

0celóñe7

@Rumplestillskin Yes to the first but no to the second

what exactly are you trying to do

Secret

It does not say when. 40 someting minutes period seemed long enough to not merge like e.g. next 5 years

Rumplestillskin

Just interested to read about non-grav forces in the general relativistic framework. I mean in newtonian gravity we express forces as linear superpositions. I am interested how this is achieved in GR @0celóñe7

Secret

@rob Python is so far ok to me as long it does not need to communicate with the bash shell and PBS pro, then is where it gets VERY ANNOYING

Rumplestillskin

2:30 AM

So as an concrete example: Compare the orbit of a satellite in the newtonian regime and relativistic regime subject to X, Y, Z non-gravitational forces. Or at least something to that effect. For the relativistic regime I imagine it is a modification to the geodesic equation to have a non-zero RHS? @0celóñe7

0celóñe7

@Rumplestillskin Yeah, but I doubt there's a general framework for such things

In some cases it's obvious I guess

Secret

If you are going to include non gravitational forces, are you talking about fictitious forces or those arise from other interactions like electromagnetism?

0celóñe7

it should also be a linear superposition

Rumplestillskin

a linear superposition? GR is fully non-linear so how could that work? @0celóñe7

@Secret when I say non-gravitational forces I mean those forces perturbing the acceleration of a satellite like solar radiation pressure etc.

0celóñe7

@Rumplestillskin you can add vectors and the RHS of the geodesic equation is a vector

Rumplestillskin

2:36 AM

@0celóñe7 have you seen this done any where before with a concrete example? I would like to see how they do it.

0celóñe7

No, but the standard reference for motion is De Felice and Clarke

they have information about extended modies/nongeodesic motion

maybe look there

Secret

arxiv.org/abs/0901.1606

hmm?

Rumplestillskin

@Secret haha I just began reading that document!!

@0celóñe7 okay I will have a look

Thanks!

Secret

Hmm... I wonder if trying to put in solar radiation pressure as part of the stress energy tensor will be a bit overkill

Rumplestillskin

Well I just used SRP as an example. Ideally I am interested in several non-gravitational forces and of course standard geodesic motion all being modelled in the framework of GR.

DanielSank

5:13 AM

I need a dummy's guide to voltage regulators.

@rob Yes "time to solution" is cited as a good reason to use Python to solve problems.

David Z

6:32 AM

@ACuriousMind my internet connection failed just after I posted :-(

it was going back and forth for a little while

apt45

9:15 AM

Hi, everyone! Do you know what is the general procedure to decompose a representation of a Lie Group into representations of some of its subgroups? For example, SU(4) contains SU(3)xU(1) and the 6-rep decomposes as $ 6 = 3_{2/3} + \bar{3}_{-2/3}$

user84215

10:03 AM

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