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/sci/ - Science & Math

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9194473 No.9194473 [Reply] [Original]

Can any physicist tell me what Gravity is?

>> No.9194513

lol no

>> No.9194571

>>9194473
curvature in space time
think about how a ball moves around in a blanket that has been pressed down in some area

>> No.9194582

Sure, it's simple. Gravity is the biggest anal fetishist out there. Whatever has a bottom part (an ass) he wants to fuck it. Thus everything that is not two dimensional and has an anus is attracted by Gravity's dick.

Hope I helped.

>> No.9194584

>>9194571

Space-time is a meme. How the fuck can empty space bend. It makes no sense and leads to all sorts of paradoxes. Show me a proof that extra dimensions exist within which space can bend. If you told me its some field that is bending, fine. Physicists are so arrogant, they think they can redefine any word to mean anything.

>> No.9194587

>>9194571
that analogy still uses gravity. what a shit analogy that relies on the very concept it tries to convey.
do you have a non-shit analogy?

>> No.9194602

>>9194584
>How the fuck can empty space bend
imagine you were a 2d creature living on the 2d surface of the earth.

you live in 2d, so the earth surface "bending" in 3 dimensions is a confusing and enraging concept for you, therefore you decide to vent your anger by shitposting about that "impossible" concept on a 2d nepalese geometry forum.

can you now imagine how silly your post must sound to a poster on 4d-chan?

>> No.9194628

>>9194584
yes because your definitons of space match the ones of mathematicians and physicists or even reality
:^)

>> No.9194631
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9194631

>>9194602
an important point to observe here is that the 2d anon can measure that his world has non-zero curvature by, for example, measuring the angles of a triangle.
so he doesnt have to assume any extra dimensions to prove that his 2d-space is curved

>> No.9194635

>>9194602

There is no fucking 2D. We live in exactly 4 dimensions, 3 of them spacial. Take your pop-sci string theory-tier bullshit and shove it. I bet if a Nobel prize winner told you that we live in an infinite dimensional universe (but the infinity -4 dimensions are just hidden, bro) and consciousness doesn't exist, and the color red is just a wavelength, you'd eat all that shit up.

>> No.9194638

>>9194635
>le angery retard
:)

>> No.9194641

>>9194628

Von Neumann was wrong with his hidden variables proof. Einstein made mathematical mistakes in his early theory. I've seen eminent physicists debate philosophy and they mostly didn't have a clue. You know all these theories came from the brain of a human trying to fit the empirical data with an explanation? I'll take my first-hand experience of the nature of reality over the musings of physicists until I see convincing evidence that I'm wrong.

>> No.9194801

A force Like electromagnetism but way weaker and stronger at greater scales.

>> No.9195133

>>9194638
holy shit this post made me spit out my milk xD

>> No.9195439
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9195439

>>9194584
How do you explain gravitational lens?

>> No.9195446

>>9194801
lol but what force?

>> No.9195451

>>9195439

You can accept that the equations governing relativity are true without accepting the space-curvature mumbo-jumbo.

>> No.9195527

>>9195451
To be fair, I have a hard time wrapping my head around spacetime curvature because it is very abstract, but it seems to be widely agreed upon by some of our top physicists. It's not as simple as the rubber sheet and ball analogy either because that only explains a two dimensional section of space. In reality, the rubber sheet would be in every degree possible, but that might be confusing when trying to explain an already confusing topic.

In the current book I am reading, Stephen Hawking states that the gravitational lens effect is "direct evidence that space and time are warped." This effect was first noticed in 1919 during a solar eclipse in Africa, "Light from a star passing near the Sun is deflected by the way the mass of the Sun curves spacetime."

I'm sure you are aware, there is no way to directly prove a theory true, only directly proving a theory false. Light bending around the Sun also leads me to the conclusion that there is some sort of curvature and the current explanation is still "true" to me.

>> No.9195585

Graviton(s) nigga

>> No.9195646
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9195646

if you have a spacetime manifold X, gravity is a connection that is locally a lie algebra valued 1-form with values in the poincare lie algebra, such that
[math] (E,\Omega):TX \rightarrow \mathfrak{iso}(d-1,1) [/math]
is a cartan connection on X

>> No.9195653

>>9194602
Im a physicist and you sound absolutely retarded for defending this

>> No.9195659

>>9194631
Wouldn't his protractor be all bendy though?

>> No.9197082

>>9194582
you know this really made me think
thanks

>> No.9197099

>>9195646
dude math jargon lmao
we're talking the nature of physical entities here not sperg descriptions of its behavior

>> No.9197154

>>9194473
It is actually a game of densities.

>> No.9197261

>>9194602
>Imagine you are an 2d creature

Why we don´t go ahead and imagine I am God, thus Christianity is totally right?

>> No.9197278
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9197278

>>9197154

https://m.youtube.com/watch?v=PqKmb7SSpTE

>> No.9197548

>>9197261
https://www.youtube.com/watch?v=N0WjV6MmCyM
Let Carl Sagan enlighten you.

>> No.9197819

>>9194473
Gravity is mediated by bosons.
Gravity is a field.
Gravity is spacetime curvature.

pick one

>> No.9197826
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9197826

>>9197819
what if i pick 3.14...because fields are spherical. see what i did there? welcome to math buddy.

>> No.9197832

>>9197548
Posting Youtube links should be instaban on 4chan.

>> No.9198391
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9198391

>>9197099
>asks what gravity is
>receives the current best explanation of gravity known to us
>get out of here with that math shit

if you just want to get high and have philosophical discussions about whatever stupid metaphysical shit neil degrasse tyson is talking about today then go back to >>>/lit/ or wherever you're from, you'll probably get something more meaningful to you there

retard

>> No.9198432

>>9194571
Has anyone observed this spacetime thing bending? It's a nonsensical concept.

>> No.9198436

>>9195646
This is why mathfags will never be able to do physics.

>> No.9198465

>>9198391
I semi-agree with them that raw math isn't an acceptable answer.
But for them to outright reject it like that, whilst on the Science & Math board is a bit too much.

>> No.9198490

>>9198432
this >>9195439 is as good as it gets

>> No.9198493

>>9198391
explain what it means at least sperg

>> No.9198501

>>9198432
light takes the shortest path between two points (this follows from quantum mechanics)

if space wasnt curved anywhere, light would only go in straight lines.
therefore observing light doing in curves (through empty space) means that that empty space must have had curvature (otherwise the shortest distance would have been a straight line)

>> No.9198513

>>9194584
>How the fuck can empty space bend.
https://en.wikipedia.org/wiki/Frame-dragging

>> No.9198517

>>9197832
rub one off anon
curb your adhd for 5min
and enjoy the video

>> No.9199185

>>9197832
I agree if the YouTube video is shit. However, I don't post shit and you should check out the video.

>> No.9200175

>>9194473
We can tell you how it works to some degree no idea what it is though that's still an open problem in physics.

>> No.9200293

>>9194473
>mfw I realize the special relativity doesn't work in any capacity unless spacetime is curved
>mfw special relativity is just a meme version of general relativity
>mfw all special relativistic effects can be explained by simple coordinate transformations
>mfw equivalence principle has the non-dimensional-bending fags BTFO instantly

>mfw I have no face

captcha: gravity buttfags

>> No.9201445

>>9194473
das dat yummy shit you pour into yo fried chicken white boi

>> No.9201550

Objects on earth are negativley charged and the earth is positive charged, therefore there's an electromagnetic field because electrons

>> No.9201561

>>9198465
>>9198391
I don't reject the math you cucks my point is that the math is a model of the physical entities behavior, but it doesn't describe the entity itself. Although I suppose you're right in calling me out on metaphysics because that IS the point I'm arguing I suppose. Physics is using math to explain behavior of phenomena, but the nature of the phenomena itself is open to interpretation
if you don't realize this you should gas yourself

>> No.9201581
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9201581

>>9198391
To be fair, you have to have a very specific phenotype to study gravity in M-theory. The mathematical framework is extremely subtle, and without a solid grasp of compactification most of the extra dimensions will go over a typical student's head. There's also Witten's soothing monotone voice, which is deftly woven into all his presentations - his personal philosophy draws heavily from the anthropic principle, for instance. The fans understand this stuff; they have the intellectual capacity to truly appreciate the depths of ultraviolet divergences, to realize that they not just diverge- they evaluate to -1/12. As a consequence people who dislike M-theory truly ARE idiots- of course they wouldn't appreciate, for instance, the humour in Susskind's existencial catchphrase "If unitarity was a woman I'd fuck her" which itself is a cryptic reference to Juan Maldacena's paper on AdS/CFT I'm smirking right now just imagining one of those addlepated simpletons scratching their heads in confusion as they see no experimental evidence unfold itself in the latest papers on arXiv. What brainlets... how I pity them. And yes by the way, I DO have a Feynman tattoo. And no, you cannot see it. It's for the ladies' eyes only- And even they have to demonstrate that they're within 5 base pairs of my own genotype (preferably lower) beforehand.

>> No.9201597
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9201597

Black holes r real.. gravity is so strong it can't let light escape.. although light has no mass it has energy due to general relativity

>> No.9201613

>>9201597
Mass and energy are the same thing

>> No.9202117
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9202117

>>9201581

>> No.9202281

>>9201581
i'm sending this to witten

>> No.9202371

>>9198391

yeah, but none of that pretentious math is really required to provide a satisfactory description of gravity, if you don't believe me, ctrl-f "cartan connection" in any one of einstein's papers. Zero results, guarenteed. You can describe gravity satisfactorily with nothing more sophisticated than physical reasoning and ricci's tensor theory. If he really wanted to explain he could have (perhaps not though, as many mathematical physicists don't actually know much physics), but he gave a two sentence grad student answer which provides no one with anything, and is designed solely to impress upon the reader some notion of the poster's superiority. It is 'iamverysmart' posturing. God, grad students piss me off sometimes.

>> No.9202373

>>9194602
r e k t !

>> No.9202535
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9202535

>>9195646
>[math]\mathfrak{so}(d-1,1)[/math]
>[math]i[/math]
Did you do a Wick rotation or what? Because if you didn't that [math]i[/math] shouldn't be there and if you did it should just be [math]\mathfrak{so}(d+1)[/math].

>> No.9202572
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9202572

>>9202535
googled poincare lie algebra, result:
https://ncatlab.org/nlab/show/Poincar%C3%A9+Lie+algebra
>[math] \mathfrak{iso}(\mathbb{R}^{d-1,1}) \simeq \mathbb{R}^{d-1,1} \rtimes \mathfrak{so}^+(d-1,1) [/math]

i've never seen the notation before either, so this is probably beyond my level, but i would bet urs schreiber invented it for some of his work

>> No.9202578
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9202578

>>9202572
Poincare is just Lorentz plus boosts. Relativistically it's [math]SO(d,1)[/math] and Euclidean is [math]SO(d+1)[/math].
Probably just another convention where the connection is [math]\nabla = d + i\Gamma[/math] instead of [math]\nabla = d + \Gamma[/math].

>> No.9202639

>>9202572
>>9202578
iso just stands for isometry group

>> No.9202642

>>9202639
Translations aren't an isometry.

>> No.9202661

>>9202642
Do you dispute that the isometry group of Minkowski space is the Poincaré group?

>> No.9202681

>>9202661
Not all of its elements preserve the inner product so it's not an isometry by definition. It's just the symmetry of the classical Lagrangian.
Why do you think it's always the case that [math]Sp(d)[/math] double covers the Lorentz [math]SO(d)[/math] and never the full Poincare?

>> No.9202689

gravity = ~ 9.8m/s acceleration of nongasses without resistance in 90degree angle vector of level water reference

>> No.9202738

>>9194473
Gravity isn't real OP, the flat earth is simply hurtling up in space at 9.81 m/s2

>> No.9202763

>>9202681
So what do you think the isometry group of Minkowski space is?

>> No.9202764

>>9202763
Just the Lorentz group.

>> No.9202773

>>9202764
>https://en.wikipedia.org/wiki/Isometry_group
>"The isometry group of Minkowski space is the Poincaré group."

>> No.9202781
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9202781

>>9202773
Oh shit you're right. Thought isometry means inner product preserving instead of just metric preserving.

>> No.9203955

>>9201561
How do I know you're a brainlet?

>> No.9203977

>>9194473
the better question is what is what?