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/sci/ - Science & Math

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8328797 No.8328797 [Reply] [Original]

What is the actual mechanism by which mass distorts space-time geometry?

>> No.8328798

>>8328797
Gravity

>> No.8328800

>>8328797
metric, curvature, and stress-energy tensors

>> No.8328803

>>8328800

But these things only describe the how the changes in geometry are related to mass and energy. What is the actual mechanism by which this happens?

Given a massive particle sitting in space-time how does it effect the surrounding space-time and distort its geometry?

>> No.8328815

>>8328803
if you find out you will become really famous :^)

>> No.8328818

>>8328815

So we don't know yet?

>> No.8328825

>>8328818
nope. and btw, it's not mass that distorts space-time, it's energy. in the case of mass, it contains so much energy that the distortion becomes very noticeable (aka gravity). a massless object with momentum would generate gravity because of the kinetic energy

>> No.8328850

>>8328797
>What is the actual mechanism by which mass distorts space-time geometry?
mass-energy is simply a distortion in space-time, not the cause of it.

>> No.8328853

>>8328797
There is no mechanism, that's just the way it is. Energy is curvature.

>> No.8328854

>>8328853

Really? All the energy and particles in the cosmos are little distortions in the space-time?

>> No.8328857

>>8328854
Yes.

>> No.8328859

>>8328857
can you explain how we know this

>> No.8328862

>>8328859
https://en.wikipedia.org/wiki/History_of_general_relativity

>> No.8329054

>>8328797
I read a biography on Einstein recently.
If I recall correctly, he was trying to find a unified field theory, where elementary particles and forces are manifestations of a single field.

In this case, by analogy, mass would be a property of a field (like space time for example), such that the distortion of -the field produces what we perceive as particles in the high density centre and gravitational "wells" at the low density periphery; particles would appear to interact with each other by gravitation because the distortions in distortions of the field act like constructive and destructive interference.

Matter and anti-matter annihilation would result in the unravelling of the distortions of field into two infinitesimally small, and thus massless, distortions (perceived as photons).

>> No.8329059

>>8328797
It's something like a gearbox, one connected to a shaft that's connected to a wheel that spinst really fast.

>> No.8329075

>>8328797
Space is curved. If a particle physicist tries to tell you about """gravitons""", stab him in the nuts.

>> No.8329080

>>8328825
>object
>massless

>> No.8329086

>>8329080
what is light

>> No.8329788

>>8328797
https://www.youtube.com/watch?v=MO0r930Sn_8

>> No.8329800

>>8328825
So if we have a really powerful photon(mass energy equivalent of the moon) bouncing between two mirrors we could make 'artificial' gravity?

>> No.8329801

>>8329788
The question is "what", not "why"

>> No.8329805

>>8329801
No difference in this case.

>> No.8329811

>>8329805
As Feynman says in that video, you need a "what" before a "why". We don't have the what.

>> No.8329812
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8329812

You're ansking a why question and it will just lead to other why questions.

The einstein equations are
G=k·T
where G is the Einstien tensor, T is the (model specific) energy/pressure density tensor and k is some constant. G is basically the second derivative of the metric tensor g, what whatever.

If T is such and such, then G is such and such. The question "How does it affect" spacetime is moot, given that they are just related by an equality sign.

Consider
a=(1/m)·F
where a is acceleration, m is mall and F is force. Now "How does force affect acceleration"? Just like so.

You could take a reductionist perspective and say: Well the deeper theory is quantum mechanics, and F=ma is just an emergent law that's just some mean values of some wave functions, and that's the how.
(A similar line of thought will work for gravity too, except we don't have a good theory of quantum gravitiy yet.)

But is that an explanation of how? You'll just look at the defining equations and quantum mechanics, say
d(psi)/dt = k·H psi
(Schrödinger equation)
and ask "how does the fundamental model/the Hamiltonian operator H change the wave function psi in time?". Well, like so.

>> No.8329815

>>8329811
I don't know what you're talking about. Please be more specific.

The OP asked "how does matter bend spacetime?". That sort of question is exactly what Feynman addresses.

>> No.8329817

>>8329812
>d(psi)/dt = k·H psi
absolutely disgusting, chemists fuck off pls

>> No.8329819

>>8329815
He's asking for an identification of the physical mechanism by which gravity interacts with matter. WHAT is it. Then you can describe how it happens

>> No.8329821

>>8329819
And the answer is "we don't know".

>> No.8329822

>>8329821
Great

>> No.8329831

>>8329819
Fundamental laws don't have mechanisms. If they did then those mechanisms would work according to fundamental laws and the law being explained would not be fundamental.

>> No.8329834

>>8329831
This.

>> No.8329837

>>8329831
gravity is not a fundamental "law"

>> No.8329843

>>8328803
>What is the actual mechanism by which this happens?
It's postulated. There's nothing deeper than that, other than quantum gravity and stuff.

>> No.8329869

>>8329834
This.

>> No.8329873

>post yfw gravitons are real

>> No.8329875

>>8329873
>physics
>>>/x/

>> No.8329876
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8329876

>>8329873

>> No.8329881

>>8329876
>implying statistical approximations aren't real actual things