Warp speed space travel and GR:

[OnlyMe]

It might yet be a thing, Only. Maybe not in classical GR, but in a quantum theory of gravity. I recall AlphaNumeric saying something about spacetime being made out of gravitons:

I miss AlphaNumeric!

Yes, but he was talking a hybrid interpretation of GR and QM. There are no gravitons in GR... but if you think about it, if anything like a graviton is involved at a quantum level, then they are force carriers and GR and space-time describe the resulting gravitational field... Or the gravitons as force carriers make up the substance or quasi-substance of space-time. Either way gravitation winds fundamentally the result an exchange of momentum.., we normally refer to as force.

I tend to think it might not be a bad idea to explore the possibility that gravitation is a local inertial bias in the presence of mass. It would explain the equivalence principle, as more than just a similarity.

 

[brucep]

It might yet be a thing, Only. Maybe not in classical GR, but in a quantum theory of gravity. I recall AlphaNumeric saying something about spacetime being made out of gravitons:

It makes physics sense that space time is comprised of gravitons in a quantum theory of gravity. In GR the analog of the graviton is gravitational radiation, waves that propagate dynamically altering the space time curvature. In quantum gravity gravitational radiation is gravitons.

 

[The God]

OnlyMe,

Thank you for educating me on quote / unquote.

You raised an interesting point.

........ and without you providing any corrective interpretation/speculation, of your own about the work you criticize, it seems to me your response is more emotional than reasoned......

I would respectfully differ on this, it is not mandated that every criticism must accompany with an alternative.

 

[The God]

Hi God,

I thought your post was/is a very interesting critique of the paper. You raised a few issues that I'm sure many of us have pondered at some point. Below is Prof. Lewis's reply. If you have any more questions/comments, just ask. I can't guarantee you that all of them will be answered to your satisfaction (or be answered at all), but I'll make sure they get there.

Thank you Tashja and thank you Prof Lewis for being so candid.

 

[The God]

Paddoboy

Below is how good Prof Lewis responded to my post.

....So, some things – Francis et al – three of the authors where grad students at the time of writing. We spent a lot of time understanding the meaning of relativity for that paper, and there have been several follow up papers on the topic. The paper is not meant to be definitive (no science is) but the level is above popular science, so I guess I must apologise if the language grates a little....

Probably you missed to read this candid observation by Prof. before writing your post. But what intrigued me was the need for you to apologize to Prof on my behalf and earlier on behalf of Danshaven. Danshaven has shown in the later posts that he is quite capable of apologizing if required and I started with an apology.

In my opinion you have not made any further value addition in the said post on the issue at hand which would inspire any comment.

 

[paddoboy]

Probably you missed to read this candid observation by Prof. before writing your post. But what intrigued me was the need for you to apologize to Prof on my behalf and earlier on behalf of Danshaven. Danshaven has shown in the later posts that he is quite capable of apologizing if required and I started with an apology.

In my opinion you have not made any further value addition in the said post on the issue at hand which would inspire any comment.

No, I missed nothing and certainly not the rather facetious demeaning tone you addressed the Prof in.
And as noted by the Prof, there does appear to be some history there anyway which may explain.
IN your opinion re my contribution, that's your take on the situation but worth noting who did start this thread.
Dan apologised for his remarks and that's where it ends as far as I am concerned.

 

[sweetpea]

Mass and energy are used to determine what the geometry of space-time is, but they do not create space-time, as even a quasi-independent thing

Can you show me where I have said in my posts that mass and energy create space-time?
If your referring to the word 'effect' in my #70 post...

Why mass and energy effect spacetime is unknown

then just replace' effect' with the word affect or alter. I do get effect and affect mixed up.
You should know I meant alter spacetime as shown below( from #70)

In a geometrical theory about the manifold of space time, it is taken as a 'given' that mass and energy do alter spacetime. .

The only thing that we know with any certainty about GR and the space-time model of gravitation is that it accurately describes what we observe......., and that it doesn't say anything certain about why or how what we observe is as it is.

Do you recall what I said ( #59) about how both the geometrical spacetime manifold theory and the 'Force idea' are both just mathematical tools for predictive purposes.

To make predictions using the geometrical spacetime manifold theory, you just take it that mass and energy alter spacetime.
The same for making predictions with the Force idea, you accept there is a force.

 

[brucep]

Can you show me where I have said in my posts that mass and energy create space-time?
If your referring to the word 'effect' in my #70 post...
then just replace' effect' with the word affect or alter. I do get effect and affect mixed up.
You should know I meant alter spacetime as shown below( from #70)

Do you recall what I said ( #59) about how both the geometrical spacetime manifold theory and the 'Force idea' are both just mathematical tools for predictive purposes.

To make predictions using the geometrical spacetime manifold theory, you just take it that mass and energy alter spacetime.
The same for making predictions with the Force idea, you accept there is a force.

Only Me seems to think there's got to be a reason why phenomena is phenomena other than it's phenomena that exists in this universe. For the most part theoretical models describe phenomena and make predictions associated with it's function. I can't think of one scientific theory that claims it knows why any of this exists. Maybe someone else can?

 

[brucep]

You were right again, OnlyMe and also brucep gets an honorable mention. Exotic matter was actually discovered at the LHC in 2014. Thanks.

If you will all excuse me for a little while, I have a few hats and some raw crow I need to eat. Maybe a few dozen apology letters to Kip Thorne are also in order.

I was wrong; not the first time, by a long shot. I'm here to learn of course. Some of us have more to learn than others.

Exotic matter with respect to this thread was predicted by Hendrick Casimir in 1948 and empirically measured by Steven Lamoreaux in 1996. The energy density between the uncharged plates is < the energy density surrounding the uncharged plates. This is the exotic matter that the warp geometry, bubble, needs to hold the walls of the bubble from collapsing. Same for the wormhole. Negative energy. At this point that would be the only way we know how to make it happen. The warp and wormhole metrics are solutions to the EFE which describe how to modify the local spacetime given a source of negative energy to hold the modified spacetime from collapsing. When you review the potential for farming an adequate source of negative energy the prospects for an FTL warp don't look to good.

 

[OnlyMe]

Can you show me where I have said in my posts that mass and energy create space-time?

I appologise if it came across that I was taking your comment out of context. My intent was an interpretation in the
larger context of the earlier discussion. It seemed to me that you were speaking of space-time as a thing. That is why I reintroduced the Professor's comment.

BTW I don't have a problem any interpretation of what space-time is or isn't. A discussion would not be of much interest if there were not differing ideas. I was only attempting to clarify, my own thought, which is in line with the way I read the professor's comment.

... And then add that I do believe that from a wholistic view, there must be some force involved in gravitation. I don't believe the, no force is felt in free fall is a convincing argument... But that would get into a whole additional discussion.

 

[OnlyMe]

Only Me seems to think there's got to be a reason why phenomena is phenomena other than it's phenomena that exists in this universe.

Yes Bruce, I do believe that even when we are unable to clearly identify it, there is a cause for every phenomena we observe. Nothing is, just because it is!... Though I am sure that there are times that it is easier to just accept, what we don't yet fully understand.

Just because it may be easier, does not mean I have to.., just accept that things are just because....

 

[The God]

Yes Bruce, I do believe that even when we are unable to clearly identify it, there is a cause for every phenomena we observe. Nothing is, just because it is!... Though I am sure that there are times that it is easier to just accept, what we don't yet fully understand.

Just because it may be easier, does not mean I have to.., just accept that things are just because....

That explains your inclusion of word force with GR in last few posts despite the fact that its GR that is being discussed about.

You are absolutely right, there got to be some cause behind any phenomenon, thats how human intelligence is programmed to think, but the question is ability to find it out.

The human race does not know the cause behind its existence, it does not mean that there is no work on these lines, great amount of philosophical and great amount of scientific pursuit is there about various aspects of human existence, philosophy has an advantage, it can invoke my name sake but science does not have that.

And moreover on the topic, you are missing that both SR and GR have substantial shred of non-intuitiveness, that roughly translates in GR as .....Mass causes distortion in the geometry of spacetime and thats how Gravity...where is the need to invoke force ??? [I should add that non intuitive theories have scope for further improvement.]

 

[OnlyMe]

First, I am not attempting to present absolutes. And I am not trying to say anyone is wrong. All I can do is present, as best as I can, what I have come to believe. I don't know that Bruce is wrong where he and I differ in mostly interpretation. I don't know with any certainty that space-time is not as AlphaNumeric may have been implying in tashja's quote.., a thing. I am really on the fence and struggle trying to reconcile sometimes logical assumptions and conclusions that don't seem to be consistent with one another.... With that in mind.

That explains your inclusion of word force with GR in last few posts despite the fact that its GR that is being discussed about. ....

My intent was not to include the word force, within the context of GR. what I was and have been attempting to convey is that as a descriptive field theory, GR does not need to account for any fundamental underlying force, but that does not mean there is none. I tend at present to believe there is...

And moreover on the topic, you are missing that both SR and GR have substantial shred of non-intuitiveness, that roughly translates in GR as .....Mass causes distortion in the geometry of spacetime and thats how Gravity...where is the need to invoke force ??? [I should add that non intuitive theories have scope for further improvement.]

The above portion in bold, is an example of the difference in how one interprets the theory of GR.

The way the above is worded sounds to me like it assumes that space-time is a thing... If space-time is a thing then its shape alters the path of objects traveling through it. But since GR does not define how mass affects the shape of space-time, it becomes difficult to exclude some active fundamental force. Whether that force acts directly between two objects (not likely) and space-time is no more than a description of the resulting dynamics, or the force is one that an object exerts on space-time conditioning it in a manner that space-time then communicates to objects moving through it (not my best guess, but not inconsistent with what I have called a modern interpretation)..., or the force is more Machian and involves more than just the two objects, but affects how they interact kinetically, in a way consistent with the GR field description... Or maybe even something else.

Thanks Tashja, I was hoping you would do that.
Using a geometrical theory about the manifold of space and time means you don't have to invoke a force or fictional force to find the path (geodesic )of a particle. I was wondering, would a force have to be invoked to explain a path in what Prof: G. Lewis is saying about 'matter tells matter how to move'.

The statement in bold above is what I was responding to, and it would probably have been clearer if I had just said that in my opinion the answer is yes, even when a few posts later tashja posted a response from the professor indicating no force was required.., (within the context of GR at least). But then my contention all along has been that when the Professor said, "The mistake people make is to treat space-time as a thing and then make suppositions of what happens in relativity based on this.", it should be taken more literally. Notice in a repost below, of the extended quote I posted earlier, that the professor began, "The concept of space-time...", and I emphasize the word concept, not with the intent to distort the professor's intent, I cannot know that with certainty from a few words, but because it is a good representation of my own interpretation.

The concept of space-time is not banished – you just have to realise what it is – the mathematical medium that tells you how mass and energy influences mass and energy. Relativity tells you how to connect events with particles and photons, and this depends upon the mass and energy distribution around it.

The mistake people make is to treat space-time as a thing and then make suppositions of what happens in relativity based on this.

My intent was to point out that as Prof. Lewis described, but in my words here.., space-time and thus GR as a geometrical theory is only describing the field dynamics. .....

I personally don't believe that space-time itself causes things to move in any particular way. I believe that space-time is better thought of as a geometric field description of how an undetermined force of gravitation affects the motion of objects..., particles, rocks planets and yes even photons.

So my intent has not been to interject a force into GR and space-time, it has been to emphasize that I tend more toward an interpretation that what we understand as gravitation is fundamentally a force, the result of which can be at least locally well described by the mathematical medium of a GR field description we refer to as space-time.

I don't tend to think of space-time as a thing, but in the spirit of AlphaNumeric's past contributions and comment on the issue, I am not certain.

I am somewhere between where I began.., with GR and struggling to reconcile more recent hypothesis and theory about inertia originating in the context of QM, which from where I currently sit, must be reconciled, for the equivalence principle to be valid...

 

[The God]

I don't tend to think of space-time as a thing, but in the spirit of AlphaNumeric's past contributions and comment on the issue, I am not certain.

The point is that most of the time uncertainty comes from the fact that in the context we talk of spacetime but visualize space. Thats the key to removing uncertainty.

Did you ponder over, what is spacetime ? Or you just jumped the gun that it must be the space as influenced by matter over the time ? No it is not, Spacetime as envisaged by Einstein's relativity is not space + time, it is just the mathematical representation, a mathematical concept, a tool as stated by Prof Lewis, nothing to do with physical reality. The enormous confusion comes once we start seeing spacetime as space as influenced over the time. That balloon analogy, that fabric analogy, that Wheeler statement...they further compounded the problem although having some relevance in the context.

I am not aware of Alphanumeric Space discussion, even Prof talks of Quantum Vacuum as negative material, there is nothing wrong in associating any materialistic property with space per say, but not with spacetime.

Let me further probe, there is this gentleman Danshawen on the board, he is assiduously trying to get into detailed argument about time, he has stated in another thread that time is more grainier than what it appears. I fully agree that space and time may not be what they appear, they are not fundamental, we need to look further.

I will add, with due respect to all involved, the fabric concept of spacetime led to pursuit towards Loop Quantum Gravity by Dr Ashtekar and all, missed application from start as spacetime has no fabric, no reality, quantum spacetime is meaningless, (Quantum of space, yes) the theory is not getting completed even after lapse of 3 decades.

Another missed application is White Hole, Worm hole and entry to new universe...all missed applications of Relativity. General Relativity just provided the Geometrical path, a coordinate system, called spacetime, Einstein never meant it the way mathematicians are pushing.

 

[OnlyMe]

I am not aware of Alphanumeric Space discussion,

AlphaNumeric is a bright young theoretical physicist who a few years back was a moderator here. A search on the name for posts in Physics & Math should give you background if you were interested.

At present it does not seem that it would be productive to continue the discussion with you. You seem to jump to conclusions yourself. And your last post seems to have run on into almost a rant! Rather than discussion.

... My formal background long gone in the past now was focused primarily on GR. I did not like QM or where it seemed to be headed at the time and now regret to some extent that I did not pursue it a little further when it would have been easy. So yes I have pondered, what space-time is and continue to do so. From a somewhat less restricted frame now than in the past.

 

[The God]

At present it does not seem that it would be productive to continue the discussion with you. You seem to jump to conclusions yourself. And your last post seems to have run on into almost a rant! Rather than discussion.

I have not made any conclusion, I had expressed that visualization of spacetime as space causes uncertainty. Spacetime is a mathematical tool, a mathematical representation, it has nothing to do with real space as perceived by us. My post will appear as rant till you realize that space and spacetime has nothing in common except few alphabets.

 

[OnlyMe]

The following two quotes both read.., to me.., as conclusions......, and the apparent conclusions.., to me.., do not seem to be consistent with what I have been saying. That may not have been your intent, but it is the way they came across.

Did you ponder over, what is spacetime ? Or you just jumped the gun that it must be the space as influenced by matter over the time ?

I have not made any conclusion, I had expressed that visualization of spacetime as space causes uncertainty. Spacetime is a mathematical tool, a mathematical representation, it has nothing to do with real space as perceived by us. My post will appear as rant till you realize that space and spacetime has nothing in common except few alphabets.

Re-read my post #93 above and then explain how or why you turn to personalizing, your assumption about what you think I believe about space and space-time.

My own characterization of the last three paragraphs of your post #94 above, as slipping into a rant, was in retrospect inflammatory and not constructive discussion on my part. I don't generally spend a long time posting or editing what I post for more than misspelling or even missing words.

I thought I was being pretty clear that in the context of GR I was in agreement with Prof. Lewis' description, to the point that I reposted it several times for emphasis. I am no longer on the other hand, blind to some of the possible implications arising from quantum theory.

 

[danshawen]

The point is that most of the time uncertainty comes from the fact that in the context we talk of spacetime but visualize space. Thats the key to removing uncertainty.

Did you ponder over, what is spacetime ? Or you just jumped the gun that it must be the space as influenced by matter over the time ? No it is not, Spacetime as envisaged by Einstein's relativity is not space + time, it is just the mathematical representation, a mathematical concept, a tool as stated by Prof Lewis, nothing to do with physical reality. The enormous confusion comes once we start seeing spacetime as space as influenced over the time. That balloon analogy, that fabric analogy, that Wheeler statement...they further compounded the problem although having some relevance in the context.

I am not aware of Alphanumeric Space discussion, even Prof talks of Quantum Vacuum as negative material, there is nothing wrong in associating any materialistic property with space per say, but not with spacetime.

Let me further probe, there is this gentleman Danshawen on the board, he is assiduously trying to get into detailed argument about time, he has stated in another thread that time is more grainier than what it appears. I fully agree that space and time may not be what they appear, they are not fundamental, we need to look further.

I will add, with due respect to all involved, the fabric concept of spacetime led to pursuit towards Loop Quantum Gravity by Dr Ashtekar and all, missed application from start as spacetime has no fabric, no reality, quantum spacetime is meaningless, (Quantum of space, yes) the theory is not getting completed even after lapse of 3 decades.

Another missed application is White Hole, Worm hole and entry to new universe...all missed applications of Relativity. General Relativity just provided the Geometrical path, a coordinate system, called spacetime, Einstein never meant it the way mathematicians are pushing.

I don't believe anyone here or elsewhere has successfully argued against the idea that the granularity of time is much finer than what is needed to explain a limit if the speed of light in a vacuum for the propagation of matter or energy. A finer granularity than that is demanded both by Maxwell's equations (to explain faster than light changes in electric fields, but not necessarily magnetic fields, according to Quantum Quack), and also for quantum entanglement to work faster than light. Entanglement is also a candidate process for energy to become bound into matter.

The argument for two quantum fields instead of just one comes from relativity, theories of particle pair creation from photons, and a recognition that the lack of an aether wind suggests quantum fields must be both at rest, and moving at c simultaneously everywhere, in every direction, all at once. I believe these respective states are different enough to require two separate quantum field descriptions. This idea may also be implemented with some success as it has been in the Standard Model using bosons as force carriers. Even a quantum field that is at rest must be at rest with respect to something else. Since matter is not a candidate for that relation, it has to be a counterpart quantum field that moves. Forces come in pairs. Entanglement happens in pairs. Particles can be created from photons in pairs. Unpaired forces don't occur in nature. Why shouldn't quantum fields also occur in pairs? Relativity is another expression of this deep symmetry. I'm not talking about gauge symmetry, although it may be related.

A weird side effect of reasoning along these lines is that infinitely sub divisible time suggests that the only way for any event pair to be simultaneous in this universe is for the events to be quantum entangled or else be the same event viewed from different directions. Pair particle creation events are what I am talking about, not the relativity of simultanaety, which is too clumsy and also coarse a description of time to be of any importance other than a description of events that occur at rates much slower than c with respect to the quantum field that is stationary.

 

[OnlyMe]

I don't believe anyone here or elsewhere has successfully argued against the idea that the granularity of time is much finer than what is needed to explain a limit if the speed of light in a vacuum for the propagation of matter or energy. A finer granularity than that is demanded both by Maxwell's equations (to explain faster than light changes in electric fields, but not necessarily magnetic fields, according to Quantum Quack), and also for quantum entanglement to work faster than light. Entanglement is also a candidate process for energy to become bound into matter.

The argument for two quantum fields instead of just one comes from relativity, theories of particle pair creation from photons, and a recognition that the lack of an aether wind suggests quantum fields must be both at rest, and moving at c simultaneously everywhere, in every direction, all at once. I believe these respective states are different enough to require two separate quantum field descriptions. This idea may also be implemented with some success as it has been in the Standard Model using bosons as force carriers. Even a quantum field that is at rest must be at rest with respect to something else. Since matter is not a candidate for that relation, it has to be a counterpart quantum field that moves. Forces come in pairs. Entanglement happens in pairs. Particles can be created from photons in pairs. Unpaired forces don't occur in nature. Why shouldn't quantum fields also occur in pairs? Relativity is another expression of this deep symmetry. I'm not talking about gauge symmetry, although it may be related.

A weird side effect of reasoning along these lines is that infinitely sub divisible time suggests that the only way for any event pair to be simultaneous in this universe is for the events to be quantum entangled or else be the same event viewed from different directions. Pair particle creation events are what I am talking about, not the relativity of simultanaety, which is too clumsy and also coarse a description of time to be of any importance other than a description of events that occur at rates much slower than c with respect to the quantum field that is stationary.

Dan, where are you getting all of this? It sounds like it belongs on the fringe somewhere. You have a lot of pieces but they seem jumbled and jammed together.

 

[danshawen]

Dan, where are you getting all of this? It sounds like it belongs on the fringe somewhere. You have a lot of pieces but they seem jumbled and jammed together.

No doubt they do. Nevertheless, it was inspired right here. I came originally to get the buzz on the Higgs boson and bits and pieces started coming together.

The quantum foam interpretation of vacuum energy dictates that time is infinitely sub divisible simply because events not entangled are separated by propagation delays. All you need to do to verify this property is to construct a timeline for those events. Got it?

Now exotic matter and dark energy and the superforce are also in play. It's been an amazing year. If it weren't for you folk, I'd have nothing near as inspiring to ponder. Thanks to each and every one of you.