Exploring Smoothness of Spacetime

[Dale]

It is physcical in what way?

Hi john 8,

Are you still using your definition that "physical" means "wave or particle"?

FYI WaveJumper, friend, et al. you may want to go back and see some of john's earlier posts, he seems to be avoiding the previous threads where he presented similar stuff. A lot of the trouble communicating with him is semantic, you have to define things clearly.

 

[WaveJumper]

Lets get back on track here.

Here is a statement that I made that you quoted in post 59

“There is no scientific reference or definition that states that space-time is a thing that exists as an entity. Please stop this science fiction fantasy. The field of science does not define space-time as a physical thing.”


Here is your response:





I asked for a scientific definition or reference that states that space-time exists as a physical entity. You have not provided any. Period!

Define "physical". Then define "Thing". Without these definitions, we are talking in different languages.

GR in the words of Wheeler:

“Spacetime tells matter how to move; matter tells spacetime how to curve.”

Spacetime can curve in the presence of immense gravity, why would it not be considered as much a thing as what you refer to as "Matter", which is nowhere being solid or absolute?

Does science define space-time as a physical entity? Y/N.

Science defines observations and experiments. Our current observations do not allow us to infer a coherent unified picture of the true nature of the classical(macro) and quantum scale.

I am not asking for your opinions on reality or discussions on T.O.E. Stop avoiding the question.

But reality(the state of existence of everything) is what you are inquiring about. A fundamental unified description of spacetime is actually Reality. You have only been asking about what reality is in this thread. No one knows, niemand weiss, никто не знает, comprendo?

Does science define space-time as a physical entity? Y/N. Just answer the question.

Science is silent(DOES NOT SAY) anything concrete about the true nature of spacetime(yet). Speculations and hypothesis about what fundamentally spacetime might be, are not a scientific definition of "spacetime". What you are looking for lies in the future.

After we have established what science says regarding space-time then we can move forward from there.

Space in qm is very diffrent from the picture of space in relativity and classical mechanics. For all intents and purposes, a good case can be made that spacelike separation does not exist, based on Bell's theorem.

The only hint we have from the purported canditate for unified theory points to spacetime not being fundamental:

"Is spacetime fundamental?
Note that there is a complication in the relationship between strings and spacetime. String theory does not predict that the Einstein equations are obeyed exactly. String theory adds an infinite series of corrections to the theory of gravity. Under normal circumstances, if we only look at distance scales much larger than a string, then these corrections are not measurable. But as the distance scale gets smaller, these corrections become larger until the Einstein equation no longer adequately describes the result.
In fact, when these correction terms become large, there is no spacetime geometry that is guaranteed to describe the result. The equations for determining the spacetime geometry become impossible to solve except under very strict symmetry conditions, such as unbroken supersymmetry, where the large correction terms can be made to vanish or cancel each other out.
This is a hint that perhaps spacetime geometry is not something fundamental in string theory, but something that emerges in the theory at large distance scales or weak coupling. This is an idea with enormous philosophical implications."

http://www.superstringtheory.com/blackh/blackh4.html

Science has established what space-time is.

Are you a time traveller holding a 3000 Mpix camera? Reference please of a unified picture of spacetime.


Suppose you were a time traveller coming from year 3112. Why would your frog view theory of the true nature of spacetime be considered complete? For all intents and purposes, this might be forever impossible.

 

[john 8]

Hi john 8,

Are you still using your definition that "physical" means "wave or particle"?

FYI WaveJumper, friend, et al. you may want to go back and see some of john's earlier posts, he seems to be avoiding the previous threads where he presented similar stuff. A lot of the trouble communicating with him is semantic, you have to define things clearly.

Alright. So what is the definition of physical according to you?

 

[john 8]

Define "physical". Then define "Thing". Without these definitions, we are talking in different languages..

I define "physical" and "thing" the same as any definition found in any standard dictionary.

Notice how no one has given a scientific definition of space-time that states space-time is a physical thing according to how science defines "physical" and "thing". STOP AVOIDING THE QUESTION AND JUST GIVE THE SCIENTIFIC EVIDENCE. Show the proof that space-time is a physical thing. Has anyone shown that space=time is a physical thing? NO. Stop giving your hopes and dreams and give scientific evidence. Space-time is physical in what way?

GR in the words of Wheeler:

“Spacetime tells matter how to move; matter tells spacetime how to curve.”

Spacetime can curve in the presence of immense gravity, why would it not be considered as much a thing as what you refer to as "Matter", which is nowhere being solid or absolute?..

Great! So what is space-time made of? Stop avoiding the question. I say space-time is not a physical thing. You say that it is, the burden of proof is on you to prove that it is. GO! What is your proof?

Science defines observations and experiments. Our current observations do not allow us to infer a coherent unified picture of the true nature of the classical(macro) and quantum scale.



But reality(the state of existence of everything) is what you are inquiring about. A fundamental unified description of spacetime is actually Reality. You have only been asking about what reality is in this thread. No one knows, niemand weiss, никто не знает, comprendo??..

Does this provide proof that space-time is a physical thing? NO. SO FAR NO EVIDENCE.

Science is silent(DOES NOT SAY) anything concrete about the true nature of spacetime(yet). Speculations and hypothesis about what fundamentally spacetime might be, are not a scientific definition of "spacetime". What you are looking for lies in the future.

So what you are saying is that you cannot provide any evidence that space-time is a physical thing. You say that space-time is a physical thing yet you cannot provide any scientific evidence to back up your claims. STOP THE DOUBLE TALK and just provide evidence that space-time is a physical thing.

Space in qm is very diffrent from the picture of space in relativity and classical mechanics. For all intents and purposes, a good case can be made that spacelike separation does not exist, based on Bell's theorem.

The only hint we have from the purported canditate for unified theory points to spacetime not being fundamental:

"Is spacetime fundamental?
Note that there is a complication in the relationship between strings and spacetime. String theory does not predict that the Einstein equations are obeyed exactly. String theory adds an infinite series of corrections to the theory of gravity. Under normal circumstances, if we only look at distance scales much larger than a string, then these corrections are not measurable. But as the distance scale gets smaller, these corrections become larger until the Einstein equation no longer adequately describes the result.
In fact, when these correction terms become large, there is no spacetime geometry that is guaranteed to describe the result. The equations for determining the spacetime geometry become impossible to solve except under very strict symmetry conditions, such as unbroken supersymmetry, where the large correction terms can be made to vanish or cancel each other out.
This is a hint that perhaps spacetime geometry is not something fundamental in string theory, but something that emerges in the theory at large distance scales or weak coupling. This is an idea with enormous philosophical implications."

http://www.superstringtheory.com/blackh/blackh4.html .

STILL NO SCIENTIFIC EVIDENCE TO BACK UP YOUR CLAIM THAT SPACE-TIME IS A PHYSICAL THING! Everyone take note that no evidence that space-time is a physical thing has been presented so far. Lots of run-a-round, but no science, NONE! Science, science, science, this is so easy, just provide scientific evidence. If you can not do this then I will have to assume that you are just making this whole thing up.

Are you a time traveller holding a 3000 Mpix camera? Reference please of a unified picture of spacetime.


Suppose you were a time traveller coming from year 3112. Why would your frog view theory of the true nature of spacetime be considered complete? For all intents and purposes, this might be forever impossible.

Forget this time traveler stuff, if space-time is a physical thing then it is physical now and now and now, show your evidence now.

THERE HAS NOT BEEN ONE PERSON ON THIS PLANET WHO HAS DESCRIBED SPACE-TIME AS A PHYSICAL THING IN SCIENTIFIC TERMS OR LAWS ACCORDING TO SCIENCE, THIS INCLUDES EINSTEIN. YOU NEED TO PROVIDE EVIDENCE TO THE CONTRARY IN ORDER TO PROVE YOUR POINT.

If you want to believe that space-time is a physical thing then just provide scientific evidence that backs up your claim. I am not asking for something unusual, just asking for evidence. Where is your evidence? Where is the science? So far nowhere to be seen.

Man up, follow the rules of this forum, or just admit that maybe there is no science that states space-time is a physical thing.

You, along with the others who believe space-time is a physical thing have been given ample opportunity to prove your point regarding space-time. Now is the time to blow me out of the water and provide your proof. I will drop this subject all together, in fact you will not hear from me again if anyone can provide scientific proof that space-time is a physical thing according to how science defines “physical” and “thing”.

I say that everything that exists and we can perceive with our senses is either a particle or a wave. If you disagree then please provide evidence to the contrary. Otherwise, if you think that space-time is a physical thing then provide evidence that it is a particle or a wave.

Space-time is physical in what way? Period.

 

[Dale]

I define "physical" and "thing" the same as any definition found in any standard dictionary.

Excellent, I am glad you have changed your mind. Then http://www.merriam-webster.com/dictionary/physical" definition 1a of "thing" is "a matter of concern". Since time and space are a matter of concern in every successful theory of physics then they are clearly physical things according to standard dictionary definitions.

 

[john 8]

Excellent, I am glad you have changed your mind. Then http://www.merriam-webster.com/dictionary/physical" definition 1a of "thing" is "a matter of concern". Since time and space are a matter of concern in every successful theory of physics then they are clearly physical things according to standard dictionary definitions.

So what is space-time made of? Do you want to say that space-time is a "of or relating to physics"? Is that an entity that exists?

"A matter of concern" is being influenced by a mass?

So what is it? Space-time is a "of or relating to physics" Is that a thing that is being influenced by a mass?

Space-time is "a matter of concern" Is that being distorted by a mass?

Come on! What is space-time made of?

 

[john 8]

Define "physical". Then define "Thing". Without these definitions, we are talking in different languages..

Physical as defined in any standard or scientific dictionary.

GR in the words of Wheeler:

“Spacetime tells matter how to move; matter tells spacetime how to curve.”

Spacetime can curve in the presence of immense gravity, why would it not be considered as much a thing as what you refer to as "Matter", which is nowhere being solid or absolute?..

So space-time is made of what?

Science defines observations and experiments. Our current observations do not allow us to infer a coherent unified picture of the true nature of the classical(macro) and quantum scale.



But reality(the state of existence of everything) is what you are inquiring about. A fundamental unified description of spacetime is actually Reality. You have only been asking about what reality is in this thread. No one knows, niemand weiss, никто не знает, comprendo?




Science is silent(DOES NOT SAY) anything concrete about the true nature of spacetime(yet). Speculations and hypothesis about what fundamentally spacetime might be, are not a scientific definition of "spacetime". What you are looking for lies in the future.?..

So science DOES NOT SAY anything concrete about the true nature of spacetime. Screw speculations. Science does not say space-time is a physical thing, yet you along with others believe that space-time is a thing. You now know that science does not agree with your assertions. Space-time is NOT a physical thing. PERIOD.

Space in qm is very diffrent from the picture of space in relativity and classical mechanics. For all intents and purposes, a good case can be made that spacelike separation does not exist, based on Bell's theorem.

The only hint we have from the purported canditate for unified theory points to spacetime not being fundamental:

"Is spacetime fundamental?
Note that there is a complication in the relationship between strings and spacetime. String theory does not predict that the Einstein equations are obeyed exactly. String theory adds an infinite series of corrections to the theory of gravity. Under normal circumstances, if we only look at distance scales much larger than a string, then these corrections are not measurable. But as the distance scale gets smaller, these corrections become larger until the Einstein equation no longer adequately describes the result.
In fact, when these correction terms become large, there is no spacetime geometry that is guaranteed to describe the result. The equations for determining the spacetime geometry become impossible to solve except under very strict symmetry conditions, such as unbroken supersymmetry, where the large correction terms can be made to vanish or cancel each other out.
This is a hint that perhaps spacetime geometry is not something fundamental in string theory, but something that emerges in the theory at large distance scales or weak coupling. This is an idea with enormous philosophical implications."

http://www.superstringtheory.com/blackh/blackh4.html





Are you a time traveller holding a 3000 Mpix camera? Reference please of a unified picture of spacetime.


Suppose you were a time traveller coming from year 3112. Why would your frog view theory of the true nature of spacetime be considered complete? For all intents and purposes, this might be forever impossible.

I asked for a scientific definition or reference that states space-time is a physical thing. You said that "Science is silent(DOES NOT SAY) anything concrete about the true nature of spacetime"

You are wrong! Science does say something concrete about space-time. The definitions that you found do not agree with what you want to believe so now you want to say science is silent. You can see that science does not recognize space-time as a physical thing.

Boo Hoo! Stop being religious and start being a scientist, physicist. Space-time is NOT A physical thing. Science says so.

LOOK AT THE EVIDENCE!

You cannot find any agreement in the scientific community to support your BELIEF.

 

[Fredrik]

I asked for a scientific definition or reference that states space-time is a physical thing. You said that "Science is silent(DOES NOT SAY) anything concrete about the true nature of spacetime"

You are wrong! Science does say something concrete about space-time. The definitions that you found do not agree with what you want to believe so now you want to say science is silent. You can see that science does not recognize space-time as a physical thing.

Boo Hoo! Stop being religious and start being a scientist, physicist. Space-time is NOT A physical thing. Science says so.

LOOK AT THE EVIDENCE!

You cannot find any agreement in the scientific community to support your BELIEF.

Not this again. John, we're really sick of this. At least I am. We have tried to explain these things to you many times, but you have ignored all the responses you got. This isn't going anywhere.

 

[jnorman]

back to the original question - i was under the impression that plank's constant indicated that spacetime was quantized. ie, spacetime is not subdividable beyond the plank length and plank time. is this incorrect, and why? thanks.

 

[Dmitry67]

back to the original question - i was under the impression that plank's constant indicated that spacetime was quantized. ie, spacetime is not subdividable beyond the plank length and plank time. is this incorrect, and why? thanks.

I was thinking that too :) But then people explained me that space is not made of "pixels": it is smooth, but distance is operator, so every time you calculate it, you get an integer value, while the coordinates can be real.

 

[Halcyon-on]

Is Spacetime Smooth?

Yes, they are (compact) smooth dimensions.

 

[Fredrik]

back to the original question - i was under the impression that plank's constant indicated that spacetime was quantized. ie, spacetime is not subdividable beyond the plank length and plank time. is this incorrect, and why? thanks.

It's certainly incorrect in general relativity, since that's a classical theory. Some version of the idea you're describing is likely to hold in a quantum theory of space and time, but we're not quite there yet.

 

[Dale]

Hi john8,

Do you agree or disagree with the statement that time is "a matter of concern of or relating to physics"?

So what is space-time made of?

Being made of something isn't part of the cited definitions of "physical" or "thing". If you would like to use a different definition that incorporates the requirement that "physical things" be "made of something" then please be explicit.

The rest of your post just follows from the fact that you seem to be using some super-secret personal definition that you don't wish to share. I have always been clear and forthright as to how I define any given term in our discussions. You, on the other hand, have been very evasive and hesitant with providing your definitions, so it is not a surprise that this semantic argument is going nowhere.

Physical as defined in any standard or scientific dictionary.

I am going to call "BS" on this. I have cited a standard dictionary definition of "physical thing" which clearly applies to space and time, and you have rejected it. Your definition obviously includes that a "physical thing" must be "made of" something, so stop hiding from the question and give us your definition.

 

[Bob_for_short]

Is Spacetime Smooth?

As a practising physicist, I will tell you - it completely depends on what you put in space and what boundary conditions you use.

 

[bebe7]

Excellent, I agree, it depends on the parameters/conditions. When a supermassive star collapses and creates a black hole, space and time will bend.

I know its a hypo but warpd drive is based on bending the fabric of space-time.

 

[strongstring]

Spacetime is definitely not 'smooth'. There is a feature known as quantum foam whereby quantum fluctuations in vacuums, matter and any other situation the space time might be in, afffects the texture of spacetime. The quantum fluctuations cause the spacetime fabric to be very 'rough the different energy levels cause it to spike and dip in areas. This is one of the factors that greatly improved the support of string physics, this is because point particles, (infinately small), can get stuck in the quantum foam, and answers for probability come up as infinty, which is nonsense. Strings however are too big to fit in these gaps and are unaffected.

Thanks
William Evans

 

[strongstring]

So what is space-time made of? Do you want to say that space-time is a "of or relating to physics"? Is that an entity that exists?

"A matter of concern" is being influenced by a mass?

So what is it? Space-time is a "of or relating to physics" Is that a thing that is being influenced by a mass?

Space-time is "a matter of concern" Is that being distorted by a mass?

Come on! What is space-time made of?

Because space time infllicts the force of gravity upon matter and energy, it is theorized to be made of gravitons, the messenger particle for gravity. another theory sugests that it is time itself, (which i really disagree on).

Thanks
William Evans

 

[Halcyon-on]

Spacetime is definitely not 'smooth'. There is a feature known as quantum foam whereby quantum fluctuations in vacuums, matter and any other situation the space time might be in, afffects the texture of spacetime. The quantum fluctuations cause the spacetime fabric to be very 'rough the different energy levels cause it to spike and dip in areas. This is one of the factors that greatly improved the support of string physics, this is because point particles, (infinately small), can get stuck in the quantum foam, and answers for probability come up as infinty, which is nonsense. Strings however are too big to fit in these gaps and are unaffected.

Thanks
William Evans

This is not physics! This is only a supposition, a conjecture not demonstrated by facts or experiment. The quantum foam is a definitely fascinating, but we are far from saying that "spacetime is definitely not smooth" because of the several incongruences of the theory.

 

[WaveJumper]

Physical as defined in any standard or scientific dictionary.

Space has properties and those properties belong to an object. They don't belong to a 'nothing'.

So space-time is made of what?

Just because no one has been able to find the "atoms" of space, doesn't mean that anything goes.

So science DOES NOT SAY anything concrete about the true nature of spacetime. Screw speculations. Science does not say space-time is a physical thing, yet you along with others believe that space-time is a thing. You now know that science does not agree with your assertions. Space-time is NOT a physical thing. PERIOD.

Science does not clearly state what 'physical' is, it's a matter of debate, but that's offtopic. Using your preconceived models of observing condensed energy as solid physical stuff and extrapolating it back to space is obviously not going to work. Space is definitely not a form of condensed energy, but its properties hint that it's definitely not a 'nothing'. BTW, no human has ever come across, or even been able to comprehend what 'Nothing' is. There is no nothing, the concept of Nothing is a misconception. Just because "nothing" works when you talk to your friends and children, doesn't mean that you can apply it in fundamental physics.

I asked for a scientific definition or reference that states space-time is a physical thing. You said that "Science is silent(DOES NOT SAY) anything concrete about the true nature of spacetime"

You are wrong! Science does say something concrete about space-time. The definitions that you found do not agree with what you want to believe so now you want to say science is silent. You can see that science does not recognize space-time as a physical thing.

Boo Hoo! Stop being religious and start being a scientist, physicist. Space-time is NOT A physical thing. Science says so.

LOOK AT THE EVIDENCE!

You cannot find any agreement in the scientific community to support your BELIEF.

Where is the evidence that "nothing" exists? What is nothing? Where am I supposed to find it or evidence of its existence?

 

[p764rds]

Space-time could not be smooth because it would need too much 'precision' to define the smallest metrics. At around the plank length the number of bits needed to define position (x,y,z and t) is around a few KB. But it would be a huge number of bits at near infinite smallness (eg Gbytes!). It is same problem as renormalization and cut off (infra red and ultra violet). - Probably around plank lengths at a guess.

Below a certain small length there is no possible action because its undefined. No actions as the length approaches zero - either at high or low energy because the length would be undefined. Its not that its outside space-time, its because any length below this cut-off is quite simply unknown or undefined. There can be no value associated with it.

 

[physical1]

There is no nothing, the concept of Nothing is a misconception. Just because "nothing" works when you talk to your friends and children, doesn't mean that you can apply it in fundamental physics.

Where is the evidence that "nothing" exists? What is nothing? Where am I supposed to find it or evidence of its existence?

Hahahaha. Yes the question of what is "nothing" is something programmers often ask.

http://c2.com/cgi/wiki?NothingIsAnything"

p.s. if there is "no nothing" then how do you define "no". No is just another word for nothing. Double none and double nuttin!

 

[WaveJumper]

Hahahaha. Yes the question of what is "nothing" is something programmers often ask.

http://c2.com/cgi/wiki?NothingIsAnything"

p.s. if there is "no nothing" then how do you define "no". No is just another word for nothing. Double none and double nuttin!

If Brukner-Zeilinger Information Interpretation is true(as i beleive), something and nothing are all the same - they are information. There are no paradoxes related to space(the disappearance of space under certain conditions, universe's boundery conditions, something out of nothing, entanglement and Bell's theorem, Zeno-like paradoxes related to whether space is continuous vs discrete, the finely tuned initial conditions, etc.). There are no time paradoxes either - the flow of time, the arrow of time, the abscence of universal now, backwards in time qausations, etc.) Hence i define "nothing" as a wrong mental image that's useful for contrasting something against a 'nothing'. It may have to do with death; if we were immortals, we'd hardly ever come up with the notion of nothing. If the Information interpretation is right, "no nothing" has the same fundamental 'content' as "nothing", just in a different sequence of bits.

 

[p764rds]

Hahahaha. Yes the question of what is "nothing" is something programmers often ask.

There is a physical 'nothing' which is where you 'cannot place an object' (Democritus et al) and where 'God lives' as someone told me yesterday.

But in our space-time the real 'nothing is a piece of undefined space-time.
Between 0.008 plank lengths and .007 plank lengths is nothing because its not defined - simple.

 

[Pythagorean]

I don't think anyone really knows, at this point. It hasn't been proved either way, but we do know that if it's quantized it must be a pretty fine-grained quantization. Reiner Hedrich, for one, has written a number of papers on the idea of quantum spacetime.

If quantum mechanics is universally true, then it's quantized. If quantum gravity turns out true, then spacetime must be quantized, so gravitons would mean quantum spacetime. As would chronons, if you believe in quantum time, but that's pretty speculative at this point.

Right now most (non-QM) models start with an assumption of smoothness, but hey--a HD TV looks pretty smooth from a distance, but we all know there are pixels when you look closely enough. I'd like to see it proved one way or the other; I'm very curious to find out which way it comes out.

--Mike from Shreveport

Thank you for this straight forward reply! I was surprised to see this thread still going.

I would just like to add (to make sure the more credible philosophical replies in this thread don't go ignored) that it's not necessary that one or the other be universally true. As Frederik and DrFaustus had replied originally, it could just be that these models are forever doomed to be limited to their 'appropriate places'.

I think you and I understand each other though and this reply is more tailored to the line of thinking I was experiencing at the time I asked the question. I've flirted many times with the idea of quantized time, but I'm hoping to get this whole quantized space business sorted out first!

 

[p764rds]

I've flirted many times with the idea of quantized time, but I'm hoping to get this whole quantized space business sorted out first!

Time must be granular for the same reason that space must be granular - the reason is, that the precision of the metrics (space an time) cannot be infinite.

You can view this as cut-off, capping, renormalization in QFT parlance.

Or, better, viewed in informational terms - the amount of data to needed to locate 1 Planck length in space-time is a few kilobits. There must be a limit that prevents it from being many giga bytes. Why? too much data would not be able to be processed in the required time. That limit will be one of the constants for this universe.

(Zeilinger work is heading in that direction)

 

[Halcyon-on]

Time must be granular for the same reason that space must be granular.

This is surely true in your own universe. But in the real universe the only think that we can state for sure is that the energy-momentum is quantized (granular), not the space-time.

 

[aussie_mike]

I worked with an electronics engineer who was completing his PhD in Physics, and he was of the opinion that space time is granular. Quantum physics and Planck constants seem to imply this. The clincher for me is that at the tiniest level a particle goes from point A to point B without traveling through the "space" between the two. Does not that define spacetime as granular?

 

[Dmitry67]

I also made a mistake assuming that minimal length implies that space is something like an array of pixels. But it is wrong analogy.

 

[jeff_kosela]

i didnt read many,... of the forums but an idea that came to mind is, on the level of quantum physics, understanding that matter is energy, i would say, no form, or build up of matter would affect super-symmetry, so in a... equation valuing these properties, id say space time,(or decay...) is constant.

 

[d9090]

If the action of Mass is quantized, then so must be the action of a "particle" with Mass on Space-Time, and the action of Space-Time on a "particle" with Mass.

Continuous Space-Time makes the mathematics easier; discrete Space-Time is closer to a "realistic" theory were the "action" known as Gravitation actually described.

But don't mind me: I'm a kook who swore off "point particles" and "ponderous matter" for Lent years ago.

d.

ps. the whole "no-thing" thing this is amusing. Surely no Marvel comic fan is getting sucked into that one! No-prizes really do exist! But then if you toss the basic idea of "reality" or "existence" you might expect a little confusion here and there. :-)

------
Emergence of Novelty: Bane of Reductionism
'As above' is not necessarily so 'below'.