Jump to content

# Space is what time looks like

## Recommended Posts

Oh. I thought gravity was a property of mass.

Mass, or really energy-momentum of 'stuff', acts as a source of gravity. Gravity itself - according to general relativity - is the local geometry of space-time.

• Replies 101
• Created
• Last Reply

#### Popular Days

Mass, or really energy-momentum of 'stuff', acts as a source of gravity. Gravity itself - according to general relativity - is the local geometry of space-time.

As a consequence, doesn't that mean that "stuff" acts as a source of Spacetime?

##### Share on other sites

As a consequence, doesn't that mean that "stuff" acts as a source of Spacetime?

Yes, but of course I have been very slack by using the word 'stuff'.

##### Share on other sites

As a consequence, doesn't that mean that "stuff" acts as a source of Spacetime?

I don't think it acts as the source of space-time, but it does affect the geometry of space-time.

##### Share on other sites

Sorry - source of the local curvature and so gravity yes.... I have no idea what source of space-time means.

##### Share on other sites

Sorry - source of the local curvature and so gravity yes.... I have no idea what source of space-time means.

You said it:

Mass, or really energy-momentum of 'stuff', acts as a source of gravity. Gravity itself - according to general relativity - is the local geometry of space-time.

Or maybe I am putting words in your mouth and you wanted to say:

"Mass is the source of the local curvature of space-time."

Edited by michel123456
##### Share on other sites

"Mass is the source of the local curvature of space-time."

Essentially this is correct.

##### Share on other sites

Essentially this is correct.

If it is correct, and if you know that essentially Space-time is made up of no "stuff" at all, why did you feel uncomfortable with the statement

(...) "stuff" acts as a source of Spacetime?

Instead of feeling uncomfortable maybe you should ask yourself more questions, like : how is that possible??

Edited by michel123456
##### Share on other sites

I don't quite follow your questions here...

'Stuff' - matter and non-gravitational fields - act as a source of gravity through the energy-momentum tensor.

##### Share on other sites

What I say is that (maybe) "stuff" is not what we observe as being "stuff". Because if "stuff" is the source of space-time around it it means that in fact "stuff" "is" (or was*) also the space-time all around it .

*because we are talking about space-time and not about space only.

##### Share on other sites

I don't know what one means be the source of space-time in a mathematical sense.

##### Share on other sites

Generally a "source" is something whose presence implies some nonzero field. A field is defined on a manifold whose dimensionality is already determined. I.e. space and time already exist, they are not fields, and nothing acts as a "source" of them. Energy-momentum acts as a source of (Einsteinian) curvature. Zero energy-momentum does not imply no spacetime, it implies flat spacetime.

Hopefully that clears up any confusion, but experience tells me it probably won't .

Edited by elfmotat
##### Share on other sites

What I say is that (maybe) "stuff" is not what we observe as being "stuff". Because if "stuff" is the source of space-time around it it means that in fact "stuff" "is" (or was*) also the space-time all around it .

*because we are talking about space-time and not about space only.

No one is saying that "stuff" is the source of space-time. Maybe it is better to think of space-time as a sort of background that "stuff" exists in. (And which can be affected by the stuff in it.)

(Although I think "background" might have some specific connotations as a technical term in physics.)

##### Share on other sites

(Although I think "background" might have some specific connotations as a technical term in physics.)

Yes, typically when one speaks of a "background" they are referring to a specific spacetime geometry. You could, for example, do field theory on top of a Schwarzschild background spacetime.

##### Share on other sites

If you actually have a model that show that 'space is an emergent principle of time', then why didn't you say so ? Lets see it please.

It's a 3-torus model with these interdependencies:

• gravity emerges from matter over time and propogates through space
• space emerges from time when under the influence of gravity

Matter and time are charged and exchange poles, the process including, time stopping at the torus extremeties

The largest "supervoid" so far found is about 1.8 billion light years across. Also, voids are not empty, they just contain slightly less matter than other areas. So your suggestions is not really testable.

You're right. I took a forced shot. I realize now you might only need a cubic inch.

The idea is that time, free of the influence of gravity, would achieve a maximum tempo (without the diversions of gravity wells time would achieve the equivalent of laminar flow) and movement, energy, and time would effectively stop.

It might take a formula to point to a path to testing. I'm working on it. I have a lead.

Black holes are as relevant as all gravitational sources, and keep the convo out of the quantum.

I'll be at a Q&A on Friday with Dr. Jared Kofron invloved with Project 8 and the University of Washington's first cyclotron radiation emission spectrometer that has observed radiation emitted by a single orbiting electron. Let me know if you think of questions I should ask or that you'd like to have asked for yourself.

##### Share on other sites

It's a 3-torus model with these interdependencies:

• gravity emerges from matter over time and propogates through space
• space emerges from time when under the influence of gravity
Matter and time are charged and exchange poles, the process including, time stopping at the torus extremeties

Great, but can you give us some more details - like the actual mathematical theory, or at least some some of the aspect.

By 3-torus you mean SxSxS?

##### Share on other sites

No one is saying that "stuff" is the source of space-time. Maybe it is better to think of space-time as a sort of background that "stuff" exists in. (And which can be affected by the stuff in it.)

(Although I think "background" might have some specific connotations as a technical term in physics.)

That is the traditional way. Newtonian.Einsteinian.

No one is saying that "stuff" is the source of space-time

I did.

##### Share on other sites

I did.

The it is up to you to make sense of this. Such an understanding is outside of general relatiivty and standard field theory - both classical and quantum.

##### Share on other sites

I have already made sense of this. A long time ago. But who listens?

The it is up to you to make sense of this. Such an understanding is outside of general relatiivty and standard field theory - both classical and quantum.

Outside yes, like in Set Theory.

##### Share on other sites

I have already made sense of this. A long time ago. But who listens?

I mean you will need a mathematical theory that show that we really can think of matter (or fields) as being the source of space-time.

Outside yes, like in Set Theory.

General relativity and field theory are based on space-time already 'existing'. A theory that has space-time as something emerging is going to be different to these existing theories - or mathematical frameworks.

I am not saying that it is impossible to create some theory - it is an interesting question and I think linked to some things in NCG and so on.

##### Share on other sites

I mean you will need a mathematical theory that show that we really can think of matter (or fields) as being the source of space-time.

General relativity and field theory are based on space-time already 'existing'. A theory that has space-time as something emerging is going to be different to these existing theories - or mathematical frameworks.

I am not saying that it is impossible to create some theory - it is an interesting question and I think linked to some things in NCG and so on.

You have the skills and the knowledge.

I believe the mathematical pieces of the puzzle are already there.

Simply take the concept that space (and the gravitational field) is the residual effect of the past of a particle.

Part 1

You would have a particle collapsing on itself, that is to say geometrically collapsing. The scale factor of the collapse would give you the value of C, or otherwise you could begin with value of C and deduce the scale factor (that would be less impressive but wathever). Because C is the value for observing the past (with C=null the particle would observe itself (its own life line only, that would be a universe of particles that cannot observe each other), with C=infinite the particle would observe the present (there would be no field, following the principle of the new theory). That would be the easy part.

You would obtain a particle and emergent Space-time.

You would also have resolved Ernst Mach question (IIRC) about the relativity of dimensions & measurements.

Part 2.

The difficult part would be to manage this ever collapsing gravitational particle in order to build something with its neighbor particle and end up with something that looks like our Universe. But this part is maybe for others. Part 1 would be already a great success. I think.

##### Share on other sites

I am not sure what a particle is without space-time, I am not sure what gravitational collapse of a particle means - with or without space-time.

The general accepted idea is as follows....

String theory, loop quantum gravity and so on all suggest that space-time at some level should be 'fuzzy' - that is described by a noncommutative geometry.

Keeping time as classical , it may be possible that the dynamics of some theory involving a noncommutative geometry - our quantum space - in some macroscopic classical limit give us space as we know it. This is plausable, but no theory has really been given yet.

However, this is would not be enough. If space comes as some classical limit then so should time - we like to treat space and time on equal footing. Now we are in trouble. We would like some theory on or of a noncommutative geometry to be such that the dynamics in some limit gives us space-time + general relativity (+ maybe small corrections). But we have to do this without time from the start. This is a big problem - we don't know how to do physics (so dynamics) without time!

##### Share on other sites

I am not sure what a particle is without space-time, I am not sure what gravitational collapse of a particle means - with or without space-time.

The general accepted idea is as follows....

String theory, loop quantum gravity and so on all suggest that space-time at some level should be 'fuzzy' - that is described by a noncommutative geometry.

Keeping time as classical , it may be possible that the dynamics of some theory involving a noncommutative geometry - our quantum space - in some macroscopic classical limit give us space as we know it. This is plausable, but no theory has really been given yet.

However, this is would not be enough. If space comes as some classical limit then so should time - we like to treat space and time on equal footing. Now we are in trouble. We would like some theory on or of a noncommutative geometry to be such that the dynamics in some limit gives us space-time + general relativity (+ maybe small corrections). But we have to do this without time from the start. This is a big problem - we don't know how to do physics (so dynamics) without time!

Mathematics are conceptually dynamical. If you use mathematics you must take time as already there. I don't think it is such a problem. If you think it differently what you are asking is to make time emerging from a static model (a model in which nothing happens). I think one can prove that it is an impossible task.

------------------------

The thing is to make space-time emergent.

-----------------------

Also I don't understand why you insist on noncommutativity. I suppose noncommutativity may come from observation, not especially from the whole geometry. IOW what we are observing & measuring may not be the whole picture.

Edited by michel123456
##### Share on other sites

Mathematics are conceptually dynamical.

Dynamical means that 'something changes' with respect to some paramaters - sometimes this can mean just 'time'. For example, just think about how to describe the position of a particle moving in 1d.

If you use mathematics you must take time as already there.

Why?

If you think it differently what you are asking is to make time emerging from a static model (a model in which nothing happens).

Like I said, no one is sure how to do physics without time. Doing so will require some new mathematical notions.

I think one can prove that it is an impossible task.

You maybe able to prove that it is impossible within a given framework - but for in total generality.

The thing is to make space-time emergent.

Meaning you want to see space and time as not being fundamental in a theory, but rather coming as a macrosopic limit and/or a classical limit or something similar. The point is that you do not want to start with space or time.

##### Share on other sites

Mathematics are conceptually dynamical. If you use mathematics you must take time as already there.

Is Pythagoras' theorem dynamical? Does it include time?

## Create an account or sign in to comment

You need to be a member in order to leave a comment

## Create an account

Sign up for a new account in our community. It's easy!

Register a new account

## Sign in

Already have an account? Sign in here.

Sign In Now

×

• #### Activity

• Leaderboard
×
• Create New...

## Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.