My understanding of Space, Time and spacetime

[halix]

My understanding of Space, Time and "spacetime"

In thinking about time I have developed the (easy) realization that whenever we indicate a duration we are comparing two spatial changes. I believe it was Einstein himself who pronounced words the effect of time being inexorably tied to space and not having an autonomous existence. This I interpret not in the sense that spacetime is a single entity and certainly not a fourth dimension, or a flow but rather that time is a local property of space.
By that I mean to say that the rate at which natural phenomena (atomic clocks ticking, cells dividing...) occur must ultimately be tied to spatial effects only.
It follows that everything that has been observed to give rise to time dilation must be inducing distortions in the three dimensional space. The effects of gravitation and the equivalent inertial acceleration are in all likelihood themselves, the manifestations of these distortions.

What are your thoughts? What the counter arguments?

 

[Bill_K]

halix, It often happens that a student new to physics finds special relativity difficult to understand, and has a "revelation" that the theory is wrong, and believes he has developed an insight that 100 years of physicists have unaccountably overlooked. You'll probably have the same opinion of quantum mechanics when you come to it. You'll have more success if you just try to learn physics at first, and not expect to revolutionize it.

 

[ghwellsjr]

There is no spatial distortion in Special Relativity and yet there is time dilation. The only distortion is in your thinking. You need to straighten out your thinking and learn about relativity, instead of promoting your personal, private, theory about relativity. It's against the rules here and will likely get you banned if you persist.

I strongly suggest that you do a lot of reading on this forum until you can learn about relativity, especially Special Relativity, which really is so much easier to understand than General Relativity, since you like easy.

 

[Spacie]

...time is a local property of space.

By that I mean to say that the rate at which natural phenomena (atomic clocks ticking, cells dividing...) occur must ultimately be tied to spatial effects only.
It follows that everything that has been observed to give rise to time dilation must be inducing distortions in the three dimensional space. The effects of gravitation and the equivalent inertial acceleration are in all likelihood themselves, the manifestations of these distortions.

What are your thoughts? What the counter arguments?

halix, I agree with you. I think the objections you have received so far is because you're not using the "right" terminology to express your ideas.

The Lorentz ether theory is experimentally indistinguishable from special relativity. Ether or not, there is a structure to space, the distortions in which GR "computes". These distortions manifest as time dilation or length contraction, because the physical processes take place in space. In my view, you're saying the same thing as GR. However, SR and GR treat space as "empty" without clarifying what it is exactly that is being distorted, nor the exact physical mechanism of how these distortions appear. Current ether theories do not give it either, but somehow they "make more sense", maybe because they do not treat space as "empty".

 

[ghwellsjr]

Spacie, in LET there is no distortion of space, just like in SR. Halix said that all time dilation is caused by a distortion of space. How do you see your comments as agreeing with halix?

 

[harrylin]

In thinking about time I have developed the (easy) realization that whenever we indicate a duration we are comparing two spatial changes.
[..]
What are your thoughts? What the counter arguments?

While you are sitting still, look at your watch. After a while, look again. The difference between those reading is the time interval (duration) of that while. What "spatial changes" are you talking about?

 

[yoron]

It doesn't really matter how one define it, as long as we agree on that it is radiation (and gravity) that defines SpaceTime. You can make it a 'whole thing' and use radiation as your proof of a 'time dilation' and Lorentz contraction, assuming a propagation. Or you can assume that SpaceTime is something defined from locality, using the same radiation as the reason why we all see it as a whole 'frame of reference', relative us observing it.

And as Lorentz contraction indeed will redefine your 'distance' with relative motion you have a certain point there. But what about your neighbors definition? Which one is true? All of them?

 

[Spacie]

Spacie, in LET there is no distortion of space, just like in SR. Halix said that all time dilation is caused by a distortion of space. How do you see your comments as agreeing with halix?

Yes, there is, and it's called time dilation and length contraction. Or do you think that when the length of, say a rod, contracts, the space it is in is unaffected? I rather think that the space in which the rod is contracts and this affects the rod that's in it.

While you are sitting still, look at your watch. After a while, look again. The difference between those reading is the time interval (duration) of that while. What "spatial changes" are you talking about?

harrylin, if nothing changes in a closed system, can you tell whether time passes for it? Your ticking clock is a change in itself. It takes energy to tick. Time is a byproduct of energy transformation. Energy transformation is a physical process that takes place in space. If space is distorted, it will affect this process, perhaps in a such a way that, judged from another RF, the time it would take to complete this process appears different.

See, ghwellsjr ? that's how I agree with halix

 

[DrGreg]

harrylin, if nothing changes in a closed system, can you tell whether time passes for it? Your ticking clock is a change in itself. It takes energy to tick. Time is a byproduct of energy transformation.

Hmm, does that mean if I put two clocks in a box, time will pass twice as fast as a box with one clock in it?

 

[Spacie]

Hmm, does that mean if I put two clocks in a box, time will pass twice as fast as a box with one clock in it?

Of course, not. A strange question, especially coming from a PF Contributor and Science Advisor. Clocks or not, the passage of time is realized only through a change of any sort. For something to change, energy must transform. No change = no time. So, in regard to the original question, time dilation can be understood as the result of a distortion of space such that the physical process, with which time is measured (usually, an atomic clock, but it could be anything) is affected.

 

[yoron]

Heh :)

And if I wind the clocks counterclockwise?
Will time go backward?

But yeah, I've also wondered about Lorentz contractions. It's weird, like everything was some 'flat surface' able to compress with motion and gravity but only in one direction, the one you're traveling, or where gravity directs you. But maybe that is all that is needed? Could one make such an assumption, to look at what would be the minimum demand for 'shrinking a distance'?

Simplistic again I'm afraid, but what I'm thinking of is this way Nature seems do as little as needed, and no more. As if you could put a Lorentz contraction it that category too?
==

Ouch Halix, missed that reply, don't take it so seriously.
He just wanted you to read up on it.

 

[harrylin]

[..]
harrylin, if nothing changes in a closed system, can you tell whether time passes for it? Your ticking clock is a change in itself. It takes energy to tick. Time is a byproduct of energy transformation. Energy transformation is a physical process that takes place in space. If space is distorted, it will affect this process, perhaps in a such a way that, judged from another RF, the time it would take to complete this process appears different. [..]

Ah yes, change (physical change) is usually spatial change. However, I wonder if this is necessarily always so. Hmm... I was thinking of radioactive decay, but that also involves a spatial change. So, there may be something to it.
Meanwhile the OP already left this thread...

 

[ghwellsjr]

Spacie, in LET there is no distortion of space, just like in SR. Halix said that all time dilation is caused by a distortion of space. How do you see your comments as agreeing with halix?

Yes, there is, and it's called time dilation and length contraction. Or do you think that when the length of, say a rod, contracts, the space it is in is unaffected? I rather think that the space in which the rod is contracts and this affects the rod that's in it.
...
See, ghwellsjr ? that's how I agree with halix

No, the space that contains a rod that has experienced a change in its length as a result of having been accelerated is not the slightest bit distorted or changed in any way. Light still travels through that region of space identically to the way it did before there was a rod there. We're not talking about water which is distorted by objects moving through it. There is never a measurable or detectable ether wind and there would be if what you and halix are saying were true. These ideas are not part of Special Relativity and anyone who believes them needs to have their thinking straightened out.

 

[Phrak]

Hmm, does that mean if I put two clocks in a box, time will pass twice as fast as a box with one clock in it?

Of course, not. A strange question, especially coming from a PF Contributor and Science Advisor. Clocks or not, the passage of time is realized only through a change of any sort. For something to change, energy must transform. No change = no time. So, in regard to the original question, time dilation can be understood as the result of a distortion of space such that the physical process, with which time is measured (usually, an atomic clock, but it could be anything) is affected.

I don't get it. Do you mean that time doesn't pass without a clock in the box?

 

[TrickyDicky]

I don't get it. Do you mean that time doesn't pass without a clock in the box?

Yeah, but it would have to be a wall clock.
Come on, are you seriously asking that?

 

[TrickyDicky]

No, the space that contains a rod that has experienced a change in its length as a result of having been accelerated is not the slightest bit distorted or changed in any way. Light still travels through that region of space identically to the way it did before there was a rod there. We're not talking about water which is distorted by objects moving through it. There is never a measurable or detectable ether wind and there would be if what you and halix are saying were true. These ideas are not part of Special Relativity and anyone who believes them needs to have their thinking straightened out.

Ether wind, what are you talking about? Nobody has mentioned that except for you.
Have you ever heard of mass-energy distorting light paths? General relativity has been around for almost a century but you seem not to have notice it.
What Halix and Spacie are saying is just a non-standard terminology account of some GR concepts like gravitational time dialtion.

 

[nitsuj]

Ether wind, what are you talking about? Nobody has mentioned that except for you.

yea that caught my eye too, sounds funny.

ghwellsjr "There is never a measurable or detectable ether wind and there would be if what you and halix are saying were true."

What's ether wind?

 

[TrickyDicky]

yea that caught my eye too, sounds funny.

ghwellsjr "There is never a measurable or detectable ether wind and there would be if what you and halix are saying were true."

What's ether wind?

Ether wind refers to the luminiferous ether theory of 19th century that was totally surpassed by Eintein theory, but I don't think it applies to anything the OP claimed, he was talking about gravity and time dilation in somewhat naive and popular terms, nothing radical as the posts of ghwellsjr and Bill_K would have us believe.

 

[ghwellsjr]

Ether wind, what are you talking about? Nobody has mentioned that except for you.
Have you ever heard of mass-energy distorting light paths? General relativity has been around for almost a century but you seem not to have notice it.
What Halix and Spacie are saying is just a non-standard terminology account of some GR concepts like gravitational time dialtion.

In defense of the OP, Spacie brought up ether in post #4 and said he thinks "current ether theories" "make more sense". I was disagreeing with him by saying that if a moving rod distorted his ether space, it would modify the light propagating through it in a detectable way which doesn't happen.

There are a lot of people who don't understand Special Relativity but think they understand General Relativity and I think this is because the time dilation caused by gravity is not reciprocal and so they can accept that without any problem but they have a very difficult time understanding how two observers in relative motion can each claim that the other is experiencing time dilation. As a result, they want to find a way to make all time dilation be like it is under gravity so that the confusing aspects of Special Relativity can be explained away. That's why I tell these people that they need to learn Special Relativity first (and because it is so much easier).

In any case, promoting false ideas about Special Relativity is not allowed on this forum and so I point it out whenever I see it. You will notice that the OP did not present himself as a learner but rather as a promoter of his personal idea. These people tend to ask for comments on their ideas in order to legitimatize their posts but it is nothing more than an attempt to entrap people who understand SR into a long drawn out process, supposedly to help the "learner", by first having to understand the nonsense they are promoting and then to pursade them of their errors, which they never accept, until the "learner" finally gets banned and the thread locked.

 

[TrickyDicky]

In defense of the OP, Spacie brought up ether in post #4 and said he thinks "current ether theories" "make more sense".

Spacie brought up LET that has little to do with the ether wind you talked about, in fact LET tried to explain away any "ether wind" which was totally discarded by the Michelson-Morley experiment.
I won't even comment on the rest of your rant.

 

[ghwellsjr]

Spacie brought up LET that has little to do with the ether wind you talked about, in fact LET tried to explain away any "ether wind" which was totally discarded by the Michelson-Morley experiment.
I won't even comment on the rest of your rant.

Did you think that I was defending or promoting ether wind or ether?

 

[TrickyDicky]

Did you think that I was defending or promoting ether wind or ether?

Promote what you wish, if possible without prejudging people.

 

[Spacie]

No, the space that contains a rod that has experienced a change in its length as a result of having been accelerated is not the slightest bit distorted or changed in any way. Light still travels through that region of space identically to the way it did before there was a rod there.

And why would light traveling through that region not do it identically to the way it did before there was a rod there? The invariance of the speed of light applies to the rod as well as to any other observer.

We're not talking about water which is distorted by objects moving through it. There is never a measurable or detectable ether wind and there would be if what you and halix are saying were true. These ideas are not part of Special Relativity and anyone who believes them needs to have their thinking straightened out.

As TrickyDicky has already pointed out, LET does not have "ether wind". Ether wind is probably the most unfortunate idea that has ever hit physics. Thankgod we're long past it and there is no need to bring it up, ever. However, there is a structure to space, which relativity, both special and general, speak of. It seems more natural to interpret relativistic phenomena from the position of the structure of space, as Halix offered. I don't see how this contradicts relativity.

 

[ghwellsjr]

No, the space that contains a rod that has experienced a change in its length as a result of having been accelerated is not the slightest bit distorted or changed in any way. Light still travels through that region of space identically to the way it did before there was a rod there.

And why would light traveling through that region not do it identically to the way it did before there was a rod there? The invariance of the speed of light applies to the rod as well as to any other observer.

You agreed with halix that "all time dilation is caused by a distortion of space" and then you said:

"do you think that when the length of, say a rod, contracts, the space it is in is unaffected? I rather think that the space in which the rod is contracts and this affects the rod that's in it."​

It sounded to me like you were stating that when a rod moves at a high rate of speed and contracts, that it causes a distortion in space (or the other way around). I disagreed and said there is no distortion of space and if there were, it would cause a measurable disturbance in the way light would travel through it.

Now the question is: what do you mean by a distortion of space?

We're not talking about water which is distorted by objects moving through it. There is never a measurable or detectable ether wind and there would be if what you and halix are saying were true. These ideas are not part of Special Relativity and anyone who believes them needs to have their thinking straightened out.

As TrickyDicky has already pointed out, LET does not have "ether wind". Ether wind is probably the most unfortunate idea that has ever hit physics. Thankgod we're long past it and there is no need to bring it up, ever. However, there is a structure to space, which relativity, both special and general, speak of. It seems more natural to interpret relativistic phenomena from the position of the structure of space, as Halix offered. I don't see how this contradicts relativity.

How in the world did anyone think I was arguing in favor of an "ether wind"?

If you want to defend what Halix offered, maybe you should explain what he offered because he never talked about a structure of space, only a distortion of space. In Special Relativity there is no distortion of space. Time dilation and length contraction have nothing to do with a distortion of space.

 

[pervect]

With the original poster storming off - or at least claiming to (I'm not quite sure why, I didn't read it that carefully, but it seemed rather hasty), perhaps it's time to start a new thread. One with less drama. Or attempts at drama.

 

[ghwellsjr]

We don't need another thread entitled, "My understanding..." that deviates from standard theory.

 

[Spacie]

You agreed with halix that "all time dilation is caused by a distortion of space" and then you said:

"do you think that when the length of, say a rod, contracts, the space it is in is unaffected? I rather think that the space in which the rod is contracts and this affects the rod that's in it."​

It sounded to me like you were stating that when a rod moves at a high rate of speed and contracts, that it causes a distortion in space (or the other way around).

I disagreed and said there is no distortion of space and if there were, it would cause a measurable disturbance in the way light would travel through it.

Now the question is: what do you mean by a distortion of space?

If you want to defend what Halix offered, maybe you should explain what he offered because he never talked about a structure of space, only a distortion of space. In Special Relativity there is no distortion of space. Time dilation and length contraction have nothing to do with a distortion of space.

The invariant speed of light servers as a "yardstick" with which you measure both time and distance (or length) in relativity. It logically requires to have length contraction and time dilation in order to be the same for all observers.

Distortion implies structure. You cannot distort something that was not "structured" to begin with, however you care to define it. See? Distortion is not possible without a "structure" or some "order".

Length contraction is the other side of time dilation, since our yardstick is the speed of light (length per time). They both imply the distortion of space due to the movement of the observer through it.

 

[ghwellsjr]

Distortion implies structure. You cannot distort something that was not "structured" to begin with, however you care to define it. See? Distortion is not possible without a "structure" or some "order".

Is this distortion in any way related to what happens to light under the influence of gravity as explained by General Relativity?

Is this structure or order in any way related to the "current theories of ether" you spoke of earlier?

 

[Spacie]

Is this distortion in any way related to what happens to light under the influence of gravity as explained by General Relativity?

Light does not get influenced by gravity. The structure of space gets influenced by gravity. The light just follows the null geodesic.

Is this structure or order in any way related to the "current theories of ether" you spoke of earlier?

No, this structure or order is implied in "empty space" through which light propagates at a constant speed.

Why, it sounds to me as if I speak to an Inquisitor hundreds years back.

 

[ghwellsjr]

Is this distortion in any way related to what happens to light under the influence of gravity as explained by General Relativity?

Light does not get influenced by gravity. The structure of space gets influenced by gravity. The light just follows the null geodesic.

Well, since my phraseology has prevented you from answering the question, I'll let TrickyDicky present the issue to you:

Have you ever heard of mass-energy distorting light paths? General relativity has been around for almost a century but you seem not to have notice it.
What Halix and Spacie are saying is just a non-standard terminology account of some GR concepts like gravitational time dialtion.

Has TrickyDicky correctly characterized your position?

 

[Spacie]

It sounded to me like you were stating that when a rod moves at a high rate of speed and contracts, that it causes a distortion in space (or the other way around). I disagreed and said there is no distortion of space and if there were, it would cause a measurable disturbance in the way light would travel through it.

But THERE IS a distortion of space (due to the motion of the observer). If there were none, the speed of light he would measure would vary in accordance with his speed. But the experiment shows that the speed of light propagating through empty space is a constant for all observers, regardless of their speed. This can happen only if 1. speed of light in empty space is a property of space itself, which makes it "a law of nature" and a constant. 2. space gets distorted by matter moving through it (it contracts in the direction of the movement with all objects contained in it contracting accordingly). To me it seems that it is you and not me or Halix who lacks true understanding and therefore is in danger of falling into heresy and sin against relativity.

 

[yoron]

Just a point. I find it meaningless to define 'time', even though I'm interested in it too. It's like a 'time dilation'. You have to fulfill a lot of prerequisites to prove it. I like to look at it as a 'clock' instead. And that 'clock' is, to my eyes, 'c'.

Anyway, you get a perfect harmony between what people experience locally, in any motion, relative what their neighbors expect them to experience as defined from their 'frame of reference'. And as 'gravity' dilates 'clocks', relative the observer, in much the same way as Einstein expected a uniform constant acceleration to do it?

And that helps me define what I call a 'frame of reference' too, I use the 'clocks', and where they will differ, for that. That we won't notice those differences doesn't mean that they aren't there. And from that definition I expect a Plank length to be the appropriate distance for any 'frame of reference' relative another. Although there are many other definitions of what 'frames of reference' should be seen as.

That makes 'c' as a constant slightly different to me, also a Plank time.
==

Eh, I do like to try to define time, but then I stumble away from relativity into Smolins world, strings and 'foams', and geometry.. Dar* In Einsteins definitions 'time' is a aspect of SpaceTime, and there it seems as pure geometry to me :)

 

[harrylin]

But THERE IS a distortion of space (due to the motion of the observer). If there were none, the speed of light he would measure would vary in accordance with his speed. But the experiment shows that the speed of light propagating through empty space is a constant for all observers, regardless of their speed. This can happen only if 1. speed of light in empty space is a property of space itself, which makes it "a law of nature" and a constant. 2. space gets distorted by matter moving through it (it contracts in the direction of the movement with all objects contained in it contracting accordingly). [..]

That's a misunderstanding, in fact the speed of light in SR situations can only be the same without distortion of space. The only model that works is one in which accelerating objects contract (or try to contract) in space - and measurements of distances in space with such objects and clocks are similarly affected. If you think that instead, "space" itself contracts with them, then you're in for Bell's Spaceship paradox (see the description in http://en.wikipedia.org/wiki/Bell's_spaceship_paradox).

 

[Spacie]

That's a misunderstanding, in fact the speed of light in SR situations can only be the same without distortion of space. The only model that works is one in which accelerating objects contract (or try to contract) in space - and measurements of distances in space with such objects and clocks are similarly affected. If you think that instead, "space" itself contracts with them, then you're in for Bell's Spaceship paradox (see the description in [PLAIN]http://en.wikipedia.org/wiki/Bell%27s_spaceship_paradox[/URL]).

Thank you for your reference to Bell's Spaceship paradox. I see no paradox. The string should not break. That is because length contraction, first of all, affects the space and, by extension, everything it contains. In computer graphics it's called scaling and is considered elementary. Less graphically or geometrically-inclined people tend to focus on objects in space, which they tend to view as independent from space they are in, which may lead them to "get the wrong answer at first". The right answer is that the string will not break and that is because everything in that frame contracts, starting with space and ending with the string in it.

So, I'm afraid that the misunderstanding in this case is all yours. Please read on length contraction in http://en.wikipedia.org/wiki/Length_contraction

Length contraction was originally postulated to explain the negative outcome of the Michelson-Morley experiment, which in fact confirmed the invariance of the speed of light for all observers, regardless of their speed (yes, I am aware of the original interpretation of their experiment). This idea later on evolved to what is known today as Lorentz transformation that is at core of SR.

 

[harrylin]

Thank you for your reference to Bell's Spaceship paradox. I see no paradox. The string should not break. That is because length contraction, first of all, affects the space and, by extension, everything it contains. In computer graphics it's called scaling and is considered elementary. Less graphically or geometrically-inclined people tend to focus on objects in space, which they tend to view as independent from space they are in, which may lead them to "get the wrong answer at first". The right answer is that the string will not break and that is because everything in that frame contracts, starting with space and ending with the string in it. [..] Please read on length contraction [..]

Then you are aware that your idea does not fit with the consensus of how SR works.
Your assumption leads to a claim that is inconsistent, as different ways to solve the same problem lead to the contrary conclusion to what you state. However, that's a different topic on its own, to be discussed (and likely it already has) in a separate thread. And gwellsjr already sketched another, similar objection. In short, the way SR works doesn't match a space that is distorted by moving bodies. And I wrote a full paper in a mainstream physics journal on SR length contraction; you can read from me.

PS: You may also want to start the topic "Why is space not deformed by Lorentz contraction?".

Harald

 

[Spacie]

Then you are aware that your idea does not fit with the consensus of how SR works.
Your assumption leads to a claim that is inconsistent, as different ways to solve the same problem lead to the contrary conclusion to what you state. However, that's a different topic on its own, to be discussed (and likely it already has) in a separate thread. And gwellsjr already sketched another, similar objection. In short, the way SR works doesn't match a space that is distorted by moving bodies. And I wrote a full paper in a mainstream physics journal on SR length contraction; you can read from me.

PS: You may also want to start the topic "Why is space not deformed by Lorentz contraction?".

Harald

Why there should be the consensus on how SR works? The important thing is that my way of looking at things does not contradict the theory, helps me to understand it better, does not lead to false paradoxes or "a wrong answer at first".

What is the claim that is inconsistent, and inconsistent with what? And what is the contrary conclusion to what I state?

You seem more flexible on a neighboring thread:

The same thing can be "explained" in many ways, and it depends on your thinking which one you find most satisfying.

Some people like a more mathematical explanation (it's because of the invariance of c that lengths and times are measured differently at different speeds) or a more physical explanation (it's because speed affects the measurements of lengths and times in the right way that c is invariant). So what one person regards to be a consequence, another person will regard as cause - it's more of an interplay of phenomena that are consistent with each other.

Speed affects the measurements of lengths, you say. All the relevant lengths of all objects at once. It seems more logical and consistent to say that the space the objects are contained in is contracted, which affects all objects in it.

 

[A.T.]

It seems more logical and consistent to say that the space the objects are contained in is contracted, which affects all objects in it.

To me it seems more logical to say that space expands for moving objects, so the moving objects occupy less space, and therefore are measured contracted. This is more consistent with rotating reference frames, where space is non-Eculidean (more space around the circumference than 2*PI*R).

 

[Spacie]

To me it seems more logical to say that space expands for moving objects, so the moving objects occupy less space, and therefore are measured contracted. This is more consistent with rotating reference frames, where space is non-Eculidean (more space around the circumference than 2*PI*R).

Yeah but with your logic the string in Bell's Spaceship paradox will certainly break, no?

 

[Spacie]

I found this quote by HallsofIvy, who is PF Mentor with 31,611 posts:

One very fundamental distinction between Lorentz and Einstein was that Lorentz's theory only allowed for the contraction of physical objects in the direction of motion- which he saw as a "real" contraction caused by the increased magnetic pull of protons and electrons in that direction. Einstein's theory requires a contraction of the space between physical objects as well.

 

[harrylin]

[..]The important thing is that my way of looking at things does not contradict the theory, helps me to understand it better, does not lead to false paradoxes or "a wrong answer at first".
What is the claim that is inconsistent, and inconsistent with what? And what is the contrary conclusion to what I state? [..]

Your answer happens to be what Bell described as the "wrong answer at first" about his Spaceship example; and Wikipedia currently summarizes the consensus about it, which is that Bell was right on this, the string will be stressed and thus it can break.

I think that it's a very sensible rule of Physics Forums to not hijack a topic; as the topic of this thread is very general, I will respect that rule and not elaborate more on that inside this thread.
If you start a thread on the topic of space distortion, keep in mind the rule against "Overly Speculative Posts".

Harald

 

[harrylin]

I found this quote by HallsofIvy, who is PF Mentor with 31,611 posts:

I do not think that he meant it in the same way as you do (it's clearly again about another subject). On a side note of this side note, his argument still looks mistaken to me. It's a fact that even PF Mentors can make mistakes.

 

[A.T.]

To me it seems more logical to say that space expands for moving objects, so the moving objects occupy less space, and therefore are measured contracted. This is more consistent with rotating reference frames, where space is non-Eculidean (more space around the circumference than 2*PI*R).

Yeah but with your logic the string in Bell's Spaceship paradox will certainly break, no?

Yes, of course. Just like a rigid disc would break, if you spun it fast (Ehrenfest paradox).

 

[harrylin]

I do not think that he meant it in the same way as you do (it's clearly again about another subject). On a side note of this side note, his argument still looks mistaken to me. It's a fact that even PF Mentors can make mistakes.

PS. Spacie: you can ask HallsofIvy if he implied, as you do, that he disagrees with the standard solution of Bell's spaceship paradox. I bet that he does not; and I think that he's not even allowed, according to the rules.

 

[Spacie]

PS. Spacie: you can ask HallsofIvy if he implied, as you do, that he disagrees with the standard solution of Bell's spaceship paradox. I bet that he does not; and I think that he's not even allowed, according to the rules.

harrylin, frankly, I do not care for Bell's spaceship paradox, as I rarely care for these mental exercises. When someone makes an actual test of it, then I will be all ears. Until then, as far as Bell's spaceship paradox is concerned, I side with the consensus at CERN that Bell discovered in their informal discussions in canteen, and that was that the string should not break. Bell thought otherwise? Oh well... Let the actual experiment decide.

As far as SR, my understanding is the same as HallsofIvy, namely, that space does contract together with objects in it. That's the issue here. He expressed his opinion very clearly. Yours is different. Let us agree to disagree.

But what does empirical evidence say? Is there any?

 

[pervect]

Just a note: the published peer reviewed papers to date do NOT agree with the "informal coffee table consensus" reported by Bell. Bell's remarks about a consensus are also secondhand, i.e. hearsay.

Note however that not everyone who agrees with Bell's result agrees with his remarks about the implications of how to teach relativity.

So you're free to think what you want, but do realize that the mainstream position is that the string will break.

 

[A.T.]

I do not care for Bell's spaceship paradox, as I rarely care for these mental exercises. When someone makes an actual test of it, then I will be all ears.

You are confusing two different questions here:
- Will the string break in reality?
- Does SR predict that it will break?
The later can be answered without any tests, and the answer is yes.

Think of it this way: In the initial rest frame all the atoms in the string and the fields that hold them together are contracting, so they cannot fill the constant distance between the rockets anymore.

In more intuitive terms you can replace the string with a chain, and consider the individual chain links as elements, which are all contracting as the chain accelerates:

At some point they cannot contract further, without breaking.

 

[Spacie]

Thank you pervect for the info. I'll keep in mind that I my opinion on this paradox differs from both Bell and mainstream. As for alleged hearsay about CERN informal consensus, Bell tells it firsthand in his own words in his How to teach special relativity.Thank you for the picture, A.T. To me it does not look right. If anything, the length contraction should push the atoms closer together, rather than drive them apart by shrinking them in the same points in space. Besides, on the picture the overall length stays the same as before "contraction", only atoms shrink. Where is contraction of the object?

 

[John232]

A lot of people take the easy way out and determine time is completely imaginary after hearing about relativity, but it still is a noun which makes it a person place or thing. Funny, how velocity isn't seen as being half part imaginary when learning d/t makes up its only parts, but then again velocity is a more concrete concept that we can view.

I think it is easier to see how real it is by explaining relativity with velocity. Say you had a magic car that could only be seen to travel at one constant speed. Well, if you are traveling quickly in the opposite direction how could it perform this "magic". Velocity is only distance and time, so then it would have to alter the time and distance you measure it's velocity with to achieve this goal.

Time can become literally a dimension. If space was a page on a flip book, then time would be the direction the pages flip on top the previous pages. Then the amount of time you expereince could be interpreted as how quickly the pages flip or how fast you move in that direction.(although, "fast" implies higher dimensional time, please insert more dimensions, lol). Then spacetime dilation can be seen as only space contraction in hyperspace if traveling in the "time direction" didn't require time. Then again gravity wells in GR still require gravity for balls to fall in warps in rubber sheets...

 

[A.T.]

Thank you for the picture, A.T. To me it does not look right. If anything, the length contraction should push the atoms closer together, rather than drive them apart by shrinking

"Contraction" itself doesn't mean "pushing" or "moving them closer". It means scaling them along one dimension, and that includes the fields that cause the bonding between them, and effectively determine the size of atoms. So if they were free to move closer together, the contracted field would move them closer together. But they cannot reduce their overall length in this scenario.

Besides, on the picture the overall length stays the same as before "contraction",

Yes. That's the scenario in Bells spaceship paradox. The distance between the rockets spanned by the chain is constant in the initial rest frame of the rockets.

Where is contraction of the object?

Which object? The chain links are individual objects which must contract according to SR. The chain as a whole cannot contract in this scenario, because the rockets keep a constant distance in their initial rest frame.

That's the given scenario. If you think the chain won't break, then try to draw a picture of the chain moving at 0.99c in the initial rest frame, when the chain links are contracted even more than in the second picture. And keep in mind that the rockets still have the same distance in that frame.

 

[A.T.]

Then again gravity wells in GR still require gravity for balls to fall in warps in rubber sheets...

No they don't. That is just a very popular, but completely wrong analogy of how GR works. There are many threads here discussing this misleading visualization.