What is the fabric of space made of

[brainstorm]

But an inherently dynamic view of the universe puts these kinds of things back together as a single action of separation - symmetry breaking. Energy spreads out to expand spacetime, and the growth of spacetime cools energy (spreads it about). Two faces of the same coin.

But cooling doesn't mean disappearance. It just means an increase in the ratio of time to energy.

Again, you then need an ontology of development that makes this an actual change in state, rather than an apparent tautology, a simple circularity. It certainly sounds circular to say that photons are spreading the spacetime they are in, and spacetime is spreading the photons it contains. Which is why a notion like vagueness becomes essential because you do get back actual change - a change from a vague potential to a crisply dichotomised outcome.

Yes, I am also interested in the relationship between EM waves and space fabric itself, but this is because I see spacetime as nothing more than energetic relations between material objects. So spacetime seems to be nothing more than energy mitigated by gravitational attraction. When the energy is expressed as momentum of massive bodies, this is more obvious than when you're looking at EM waves themselves flattening out, because if they eventually fail to reach a target, how did they create spacetime? I believe the answer may lie in the way a rocket in space generates thrust without pushing against except what it is emitting. Stars may generate space by pushing against the photons they emit - but I have heard counterarguments against this too.

The rest of your post sounded like pure buzz. I'm not saying that that's all it is. Just the way you throw all those words and concepts out like that without explicating concrete reasoning for any of gives it the appearance of buzz. You may not have the patience and care to break individual concepts down into detailed reasoning/logic.

 

[apeiron]

But cooling doesn't mean disappearance. It just means an increase in the ratio of time to energy.

Something does disappear - or more correctly, gets minimised. And that is the general entropic gradient. The heat disappears into the production of the space leaving a heat death.

You seem to want to say that energy cannot be destroyed, so it must get transformed into something (like material in the form of black holes). Yet the citations I provided show how ultimately (in the universe as we now observe it) black holes will be embedded in a spacetime fabric so cold they must evaporate - radiate away that localised energy. So eventually, all radiation becomes part of the flat fabric. The blackbody radiation of event horizons in a de sitter spacetime.

this is more obvious than when you're looking at EM waves themselves flattening out, because if they eventually fail to reach a target, how did they create spacetime?

That is the point of the Lineweaver/Davies work - the beautiful idea of holographic bounds. The event horizons of spacetime are the "target" that gets reached by radiation.

I believe the answer may lie in the way a rocket in space generates thrust without pushing against except what it is emitting. Stars may generate space by pushing against the photons they emit - but I have heard counterarguments against this too.

OK, we are back to Newtonian viewpoints which are simply going to lead you in false directions. The idea of back-reaction may have some uses, but not in the way you are suggesting here.

Certainly, even if there was some contribution by stars in the fashion you imagine, it would have to be a vanishingly small component of the cosmic action. If all the entropy contained in all the stars was immediately converted to CMB radiation, it would add only 1 per cent to the universe's total.

This is why reading http://www.mso.anu.edu.au/~charley/papers/LineweaverChap_6.pdf would be good. It addresses these basic questions.

The rest of your post sounded like pure buzz. I'm not saying that that's all it is. Just the way you throw all those words and concepts out like that without explicating concrete reasoning for any of gives it the appearance of buzz. You may not have the patience and care to break individual concepts down into detailed reasoning/logic.

From my point of view, I show quite a bit of patience breaking down both what I think, and what also other people think .

Davies and Lineweaver are both very clear communicators. So perhaps you will suffer less buzz if you just read them.

 

[brainstorm]

Something does disappear - or more correctly, gets minimised. And that is the general entropic gradient. The heat disappears into the production of the space leaving a heat death.

And by "production of space" do you mean something other than increasing distance between surrounding objects? If not, wouldn't the increase in distance translate into a propulsion? E.g. if a car on a long carpet would stay in place and use its wheels to bunch up the carpet behind it and just assume that the carpet could be floating on a liquid, then as the bunched folds of the carpet expanded, the car would be propelled forward along with the part of the carpet it was sitting on. So the expansion of the folds in the carpet could be seen as entropy but also as propulsion at the same time. So if the dissipation of EM waves results in increasing distance between the point of emission and the destination, has energy been lost or converted into distance/space?

You seem to want to say that energy cannot be destroyed, so it must get transformed into something (like material in the form of black holes). Yet the citations I provided show how ultimately (in the universe as we now observe it) black holes will be embedded in a spacetime fabric so cold they must evaporate - radiate away that localised energy. So eventually, all radiation becomes part of the flat fabric. The blackbody radiation of event horizons in a de sitter spacetime.

Ok, so if black holes evaporate into radiation, then their mass eventually gets converted into spatial expansion - if the idea of EM waves expanding into distance/space is correct. Still, the distance/space between particles and waves is only relevant as long as these are gravitationally connected. What happens to the energy of distance/space when the objects it separates have evaporated into pure energy? Can it really just vanish or mustn't it transfer to the spatial relations among other objects/particles?

My guess would be the cold-matter of the universe would eventually begin converging once radiation-production has ceased. I am guessing Hawking radiation would not be enough to maintain positive expansion. In that case, the remaining black holes would begin accelerating toward each other due to their gravity and the amount of energy they generated en route to each other would correlate with the amount of distance between them, which would theoretically convert that distance/space back into radiation, no? Possibly such a convergence would result in a big-bang as all the black holes would approach C together in mutual orbit.

OK, we are back to Newtonian viewpoints which are simply going to lead you in false directions. The idea of back-reaction may have some uses, but not in the way you are suggesting here.

Ironically, the idea that EM radiation becomes space/distance is like an Einsteinian "spacetime fabric" way of explaining propulsion. It's just that the source of the energy doesn't "go anywhere" except away from its surroundings, right?

[/quote]Certainly, even if there was some contribution by stars in the fashion you imagine, it would have to be a vanishingly small component of the cosmic action. If all the entropy contained in all the stars was immediately converted to CMB radiation, it would add only 1 per cent to the universe's total.[/quote]
So what is the rest?

From my point of view, I show quite a bit of patience breaking down both what I think, and what also other people think .

Thank you for your gracious patience :)

 

[apeiron]

Ok, so if black holes evaporate into radiation, then their mass eventually gets converted into spatial expansion - if the idea of EM waves expanding into distance/space is correct. Still, the distance/space between particles and waves is only relevant as long as these are gravitationally connected. What happens to the energy of distance/space when the objects it separates have evaporated into pure energy? Can it really just vanish or mustn't it transfer to the spatial relations among other objects/particles?

No, the cites I provided explain that in a realm of pure radiation - a relativistic gas - the photons span event horizons. Now this does start to look like a virtual sizzle of interaction. All we have left is the self-interaction of the vacuum. But it continues to have a pressure, it continues to expand, it continues to have the same essential dissipative structure.

My guess would be the cold-matter of the universe would eventually begin converging once radiation-production has ceased. I am guessing Hawking radiation would not be enough to maintain positive expansion. In that case, the remaining black holes would begin accelerating toward each other due to their gravity and the amount of energy they generated en route to each other would correlate with the amount of distance between them, which would theoretically convert that distance/space back into radiation, no? Possibly such a convergence would result in a big-bang as all the black holes would approach C together in mutual orbit.

A recollapse is possible but the current evidence suggests not only is there enough material in various forms to keep the universe expanding in unbroken inertial fashion, but there is a weak dark energy acceleration on top of things.

But yes, a recollapse would mean a reconcentration that made things hot again. Or hot, small and once more vague, I would say.

Ironically, the idea that EM radiation becomes space/distance is like an Einsteinian "spacetime fabric" way of explaining propulsion. It's just that the source of the energy doesn't "go anywhere" except away from its surroundings, right?

I am suggesting it goes into its surroundings, into creating its surroundings.

So what is the rest?

The papers explain this. It is the CMB. When the big bang cooled sufficiently, anti-matter and matter could condense out. But almost all of it immediately annihilated to create the spreading/cooling CMB. A tiny fraction of matter remained. Which will eventually get swept up into black holes and radiated away too.

 

[brainstorm]

All we have left is the self-interaction of the vacuum. But it continues to have a pressure, it continues to expand, it continues to have the same essential dissipative structure.

Dissipative in what sense? That decreasing pressure draws particles/energy from higher pressure surroundings?

I am suggesting it goes into its surroundings, into creating its surroundings.

By "surroundings," I meant energetic matter and EM waves. What did you mean?

When the big bang cooled sufficiently, anti-matter and matter could condense out. But almost all of it immediately annihilated to create the spreading/cooling CMB. A tiny fraction of matter remained. Which will eventually get swept up into black holes and radiated away too.

So most of the energy of the initial big bang went into expansionary motion then? Would you agree that spatial separation between matter is a form of potential energy? Or do you think potential energy simply dissipates as objects move into ever weaker orbits in a gravitational field?

 

[apeiron]

So most of the energy of the initial big bang went into expansionary motion then? Would you agree that spatial separation between matter is a form of potential energy? Or do you think potential energy simply dissipates as objects move into ever weaker orbits in a gravitational field?

Of course matter is a temporary added complication to the basic picture. I am talking about the basic picture - which is just a bath of radiation spanning event horizons in comoving volumes. Or rather, that is what Davies and Lineweaver are talking about.

So there would be no localised gravitational potentials as the CMB is so evenly spread.

 

[brainstorm]

Of course matter is a temporary added complication to the basic picture. I am talking about the basic picture - which is just a bath of radiation spanning event horizons in comoving volumes. Or rather, that is what Davies and Lineweaver are talking about.

So there would be no localised gravitational potentials as the CMB is so evenly spread.

I'm confused. As far as I know there is no existence of "space" except as separation between points of matter despite their gravitational attraction for each other. Even massless energy is supposed to trace the contours of spacetime as defined by gravitational field topography. What defines the event horizons and comoving volumes except energized matter? If massless energy itself can stake off gravitational topography, how does that occur? How can photons exert gravitation without mass?

 

[Dmitry67]

If massless energy itself can stake off gravitational topography, how does that occur? How can photons exert gravitation without mass?

Again, Mass is not a source of gravity
Stress energy tensor is.

 

[robheus]

What are thoughts "made of"?

Space is merely a concept to differentiate different locations of objects in three dimensions.

In the theory of relativity space should be thought of a space-time and space-time itself does not have independend existence from matter/energy.

So, you could say that space-time is the mode of existence of matter/energy.

Space-time is not "made" of something else, yet space-time is never completely empty of matter/energy.

So, physical space is not just abstract mathetamatical geometry, where there is space-time there is matter/energy and vice versa.

 

[brainstorm]

So, physical space is not just abstract mathetamatical geometry, where there is space-time there is matter/energy and vice versa.

Good post. I think you could look at space as the vacuum inside a closed, de-pressurized container. The walls of the container are impelled to collapse into each other except the tensile strength prevents them from doing so. However, since there is no container-wall around the Earth, sun, galaxies, etc., the force pulling objects and particles apart has to be dynamic energy, from the big bang or just their motion relative to each other or however you describe it. Gravity is interesting, though, in that it relaxes as things move farther away from each other, so the "vacuum" elasticity relaxes as distances increase. So as gravity approaches zero, it seems like space could simply transcend gravitational relations, but how could gravitational attraction between two objects ever reach absolute zero? If it can't, then how could space-time ever exist in the absence of matter-energy?

 

[planck]

First of all, I'm glad that this thread is still alive and kickin!

What are thoughts "made of"?

You can quantify a thought. I would think that a synapse is fired and from there (or maybe a little before that) you could trace the path of that physical process within the brain. I think the argument could be made that the energy involved in a thought is tangible.

Space has to be tangible too.

Space-time is not "made" of something else, yet space-time is never completely empty of matter/energy.

Then why is it curved. That's the real question that I have. If space and time are intertwined, then there has to be something that links it. A "velcro" perhaps.

I'm tellin ya, space is something.

 

[GeorgCantor]

First of all, I'm glad that this thread is still alive and kickin!



You can quantify a thought. I would think that a synapse is fired and from there (or maybe a little before that) you could trace the path of that physical process within the brain. I think the argument could be made that the energy involved in a thought is tangible.

Energy is not a thought and a thought is not energy.

Either thoughts aren't real or energy isn't real. You could believe that thoughts are emergent but nothing could stop you from believing, for instance, that God is emergent from the configuartion of galaxies in the observable part of the universe.

 

[nismaratwork]

Thoughts are the result of the transmission of energy in the form of electrical impulses and neruotransmitters. It is not a matter of one synapse, but many. If you think that a thought cannot be quantified, you'll have to explain that to EEG rigs that allow people to type on a screen. Our technology isn't at the "mind reading" stage, but that doesn't mean that such would be impossible. That is a completely different issue from what constitutes spacetime.

GeorgCantor: Your either or is misleading, I assume for the purposes of introducing religion... again.

 

[robheus]

Space has to be tangible too.



Then why is it curved. That's the real question that I have. If space and time are intertwined, then there has to be something that links it. A "velcro" perhaps.

I'm tellin ya, space is something.

It's matter/energy that connects space and time.

 

[nismaratwork]

It's matter/energy that connects space and time.

That seems unlikely; energy exists within spacetime, not as some connective tissue between two 3 and +1 dimensions.

 

[GeorgCantor]

GeorgCantor: Your either or is misleading, I assume for the purposes of introducing religion... again.

I believe it's not. And it has nothing to do with religion.

Thoughts are the result of the transmission of energy in the form of electrical impulses and neruotransmitters. It is not a matter of one synapse, but many. If you think that a thought cannot be quantified, you'll have to explain that to EEG rigs that allow people to type on a screen.

Who/what is typing on the screen?

You are making it sound like it's something so simple when in fact it's the most mind-bending occurence in nature.

Either we don't have freewill and consequently thoughts are illusion, or we have freewill but matter is an illusion. One could assume emergent phenomena but it will not be satisfying to everyone.

 

[planck]

Here's some food for thought. Imagine it's T=0. At this time, existence is non-existent. But the theory is that a great explosion occurred that introduced existence. If we want to take the cosmological route, we can speculate that the hole where existence was introduced came from somewhere (parallel universe planes touching each other ?). Now, take into account that there is a theory that our gravity is leaking constantly. Where's it going? But more importantly, where's it coming from? Are there holes and fissures in our spacetime where things are coming and going? Could space itself be "leaking?" It's already stretching.

 

[alt]

Here's some food for thought. Imagine it's T=0. At this time, existence is non-existent. But the theory is that a great explosion occurred that introduced existence. If we want to take the cosmological route, we can speculate that the hole where existence was introduced came from somewhere (parallel universe planes touching each other ?).

But if there was somewhere from where existence was introduced, wasn't THAT somewhere, itself existence ?

 

[alt]

Who/what is typing on the screen?

Interesting question. Who formed that thought ? And who thought to form THAT thought ? Sounds like an infinite regress .. or emergent phenomena (whatever that means).

 

[robheus]

Here's some food for thought. Imagine it's T=0. At this time, existence is non-existent. But the theory is that a great explosion occurred that introduced existence. If we want to take the cosmological route, we can speculate that the hole where existence was introduced came from somewhere (parallel universe planes touching each other ?). Now, take into account that there is a theory that our gravity is leaking constantly. Where's it going? But more importantly, where's it coming from? Are there holes and fissures in our spacetime where things are coming and going? Could space itself be "leaking?" It's already stretching.

You are running into deep problems with this kind of propositions. A time at which time began can by definition not exist since when you referring to "begin" you already assume time to exist, so this means time can not be said to have begun at all.

 

[robheus]

But if there was somewhere from where existence was introduced, wasn't THAT somewhere, itself existence ?

right.

It's a meaningless thought to think that "existence" somehow "began".

Even though you can gramatically express such grandiloque internally contradicting statements, they have no semantical meaning.

 

[Noja888]

My Brother and I have a saying I think he said it first - not sure if we stole it from somewhere...

"Space is Time demonstrated - Time is Space demonstrated" - I would propose time as we observe it did not begin until space began. Both seem interconnected and I am guessing the true mechanism of space and time are on a higher tier level of existence. If you can travel light speed, time stops for you relative to everything else. Is that 'catching up with time' as space-time information 'moves' at the speed of light you are now moving at the same speed? Time will affect you less because you caught up to its motion. Its motion is not linear like the 3 spatial dimension motion we are familiar with but motion in the time direction. Loosely speaking here of course - I am not a PHD!

 

[Boy@n]

Very interesting posts. I'm missing two things though.

First, an answer to already made (and repeated) question, how can mass curve space-time if it's just mathematical geometry and not something physical?

Second, none mentioned background radiation - even if space has no physical property per-se it's still far from being absolutely empty, since there is background radiation in whole Universe plus quantum fluctuatins also present in all of space.


If you let me (a non-scientist) to do a bit of pondering and questioning...

Could it be that the more massive stellar objects the more intensite become quantum fluctuations around these objects, so that virtual particles popping in and out of existence somehow affect path of light waves by curving it which then makes it look as if space is curved but in truth it isn't?

Another thought, if a black hole curves space-time onto itself, might a 'huge' enough black hole 'suck' all of space, actually whole Universe, into itself - into ultimate singularity (following by another Big-Bang)?

What if beyond horizons of observable Universe there already are such critically super-massive black holes pulling 'our' Universe appart, thus making it appear as if it expands by itself? (Which would also dismiss the lacking mass/energy needed to explain accelerated expansion of Universe.)

I guess that via cosmological island theory one might visualize that there are many such 'special' black holes in every Universe, which affect one another by making some Universes expand and others collapse, and role if this being constantly changing.

 

[Dmitry67]

First, an answer to already made (and repeated) question, how can mass curve space-time if it's just mathematical geometry and not something physical?

There is no clear difference between 'mathematical' and 'physical' in fundamental physics.
There is even a claim ( http://en.wikipedia.org/wiki/Mathematical_universe_hypothesis ) that in TOE there should be absolutely no difference.

Could it be that the more massive stellar objects the more intensite become quantum fluctuations around these objects, so that virtual particles popping in and out of existence somehow affect path of light waves by curving it which then makes it look as if space is curved but in truth it isn't?

No, light is slowed down (not curved) by virtual particles, but this effect is about 10^-33

Another thought, if a black hole curves space-time onto itself, might a 'huge' enough black hole 'suck' all of space, actually whole Universe, into itself - into ultimate singularity (following by another Big-Bang)?

No, radius of BH is proportional to its mass

What if beyond horizons of observable Universe there already are such critically super-massive black holes pulling 'our' Universe appart, thus making it appear as if it expands by itself? (Which would also dismiss the lacking mass/energy needed to explain accelerated expansion of Universe.)

It does not agree with the observational data

 

[Boy@n]

Thanks for your answers. Just one more quick question. If there are two "currents" (well, there are more, but let's say there are just two), in one where quantum activity is higher than in another, and if light travels in between these two currents, wouldn't on one side of light traveling path, with higher quantum activity, happen a "faster" effect of slowed light, than on the other side, so, make the light traveling path curve? (I am visualizing currents in water, where this would be the case, but probably not with light, just had to ask.)

 

[brainstorm]

Thanks for your answers. Just one more quick question. If there are two "currents" (well, there are more, but let's say there are just two), in one where quantum activity is higher than in another, and if light travels in between these two currents, wouldn't on one side of light traveling path, with higher quantum activity, happen a "faster" effect of slowed light, than on the other side, so, make the light traveling path curve? (I am visualizing currents in water, where this would be the case, but probably not with light, just had to ask.)

This is something I've been wondering about too, except I've been thinking about it in terms of wavelength/frequency. If two beams of different frequencies interact in a certain way, could a tension form between their tendency to travel forward in a straight line and another tendency to conform to the wavelength of the other beam it is in contact with? In other words, if a beam of yellow light runs parallel to one of red light, could the red light wavelength contract a bit when they come into contact and by doing so cause a contraction on one side of the beams so that they curve in the direction of the lower wavelength?

 

[Dmitry67]

Thanks for your answers. Just one more quick question. If there are two "currents" (well, there are more, but let's say there are just two), in one where quantum activity is higher than in another, and if light travels in between these two currents, wouldn't on one side of light traveling path, with higher quantum activity, happen a "faster" effect of slowed light, than on the other side, so, make the light traveling path curve? (I am visualizing currents in water, where this would be the case, but probably not with light, just had to ask.)

You should check this:
http://en.wikipedia.org/wiki/Scharnhorst_effect

The Scharnhorst effect is a hypothetical phenomenon in which light signals travel faster than c between two closely-spaced conducting plates than in a normal vacuum
The effect, however, is predicted to be minuscule. A photon traveling between two plates that are 1 micrometer apart would increase the photon's speed by only about one part in 10^-36. This change in light's speed is too small to be detected with current technology, which prevents the Scharnhorst effect from being tested at this time.