Gravity Emergent: Matter or Big Bang?

[wolram]

To my way of thinking gravity must have been there at a very early stage for black holes to form, The thing is I can not find a definitive answer to my question.
If gravity is a distortion of space time then matter must have come first, or were the distortions of space time a relic from the big bang?

 

[Arman777]

To my way of thinking gravity must have been there at a very early stage for black holes to form, The thing is I can not find a definitive answer to my question.
If gravity is a distortion of space time then matter must have come first, or were the distortions of space time a relic from the big bang?

Gravity is a law of physics. It was always been there.

You are asking I guess without matter how gravity works ?

 

[MathematicalPhysicist]

Gravity is a law of physics. It was always been there.

You are asking I guess without matter how gravity will works ?

It's not a testable question, unless there are immaterial beings like ghosts.

And that's metaphysics.

 

[MathematicalPhysicist]

I would say that gravity won't work without matter, it's intrinsic property of matter, specifically mass.

 

[Vanadium 50]

What a mess! This whole thread is in Humpty-Dumpty land!

That's not what "emergent" means. Emergent means that gravity is the result of some other physics. For example, in the now-discredited LeSage theory, gravity would be emergent.

 

[kimbyd]

To my way of thinking gravity must have been there at a very early stage for black holes to form, The thing is I can not find a definitive answer to my question.
If gravity is a distortion of space time then matter must have come first, or were the distortions of space time a relic from the big bang?

To add a bit to what Vanadium 50 said, gravity being "emergent" doesn't mean it wasn't always there. The terminology is used to describe theories where there's something fundamental going on that looks very different from curved space-time at a microscopic level, but that behavior ends up approximating curved space-time at a macroscopic level.

For example, imagine if space-time was divided into discrete points in time and space, and particles could only exist at individual points, but the presence of energy or momentum actually changes the number of points that are available, and the specific way that matter interacts with the number of points behaves like curved space-time.

The above idea is probably impossible (at least in its simplest formulation: an irregular grid of points implies that momentum wouldn't be conserved). But I think it illustrates the concept of emergent gravity well enough.

 

[wolram]

Thank you for your replies.

 

[JMz]

I would say that gravity won't work without matter, it's intrinsic property of matter, specifically mass.

More properly, gravity won't work without mass. But the mass can be in the form of photons. No ghosts, but it need not be matter.

 

[kimbyd]

More properly, gravity won't work without mass. But the mass can be in the form of photons. No ghosts, but it need not be matter.

Photons don't have mass.

Gravity interacts with energy, momentum, pressure, and twisting forces. For normal matter outside of exotic situations like neutron stars, the mass energy is so much greater than the other components that it dominates all of those other components.

Photons, by contrast, have as much energy as they have momentum (or pressure, in the situation of a photon gas).

 

[jbriggs444]

Photons don't have mass.

A photon has no mass. A collection of photons can have non-zero mass.

[Not that this is very relevant. Gravity (curved space-time) arises from the stress-energy tensor, not merely mass]

 

[PeterDonis]

Thread closed for moderation.

Edit: a very large thread hijack has been deleted and the thread will remain closed