# The Naked Scientists Forum

### Author Topic: Is distance an absolute invariant?  (Read 16311 times)

#### Thebox

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##### Re: Is distance an absolute invariant?
« Reply #200 on: 10/02/2016 19:51:53 »
I think if the observer spun  with an orbiting object there would be no contraction.

#### timey

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##### Re: Is distance an absolute invariant?
« Reply #201 on: 10/02/2016 20:01:48 »
imperceptibly

If the speed is a constant 3 mph, and the observer is relatively stationary, all the carriages will look the same length to the observer. If the train accelerates, there will be a variation length of the carriages, they will get ''shorter'' the faster the acceleration the more carriages going past at a faster rate.

No box, read the post again.  Changes in the gravitational field, change the 'rate' of time.  (Look up NIST ground level general relativity experiments 2010). This is synonymous to counting as a means of timing an event, one, one thousand, two, one thousand, etc, at a faster, or slower rate, ie: speaking the words faster or slower.  Do you get it?  Therefore a constant speed will take a longer or shorter amount of 'time' to cover the same unit of distance.

This having nothing to do with an acceleration of speed, and my question to Alan is:
How do the effects of special relativity have an effect on the general relativity observations of the observer?

#### Space Flow

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##### Re: Is distance an absolute invariant?
« Reply #202 on: 10/02/2016 21:25:13 »
Surely the special relativity effects only apply to the accelerated reference frame?
Timey, SR does not in any way address or describe any accelerated frame.
SR is only about constant relative speed between observers. It is a good way of describing relativistic time dilation and length contraction "principles" but does not actually apply to any known real situation in the Universe.
That is the reason that Einstein kept on working on and finally brought out GR as a way of applying the concepts that SR introduced to real world scenarios.

#### Ethos_

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##### Re: Is distance an absolute invariant?
« Reply #203 on: 10/02/2016 21:30:03 »

I understood length contraction in the first place, a meaningless parlour trick, relative to the object, the object does not contract it just appears to contract to the observation.
OK, now that we can agree in part, we should examine how we can determine whether or not the object actually shrinks as it appears to. One thing we should also agree upon Mr. Box, is all the evidence we have to consider this question comes to us through observation and mathematical constructs.

You believe, if I'm not mistaken, that the object doesn't actually shrink, it only appears to shrink. What observational evidence or mathematical evidence do we have to support that conclusion?

Bare in mind, I'm not attacking you with this question, I am only presenting you with a thought experiment for us to think about.

#### Thebox

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##### Re: Is distance an absolute invariant?
« Reply #204 on: 10/02/2016 21:36:01 »
.  Changes in the gravitational field, change the 'rate' of time.

Change the rate of time of what?

#### timey

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##### Re: Is distance an absolute invariant?
« Reply #205 on: 10/02/2016 21:38:49 »
.  Changes in the gravitational field, change the 'rate' of time.

Change the rate of time of what?

LOL!

#### Thebox

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##### Re: Is distance an absolute invariant?
« Reply #206 on: 10/02/2016 21:38:54 »

I understood length contraction in the first place, a meaningless parlour trick, relative to the object, the object does not contract it just appears to contract to the observation.
OK, now that we can agree in part, we should examine how we can determine whether or not the object actually shrinks as it appears to. One thing we should also agree upon Mr. Box, is all the evidence we have to consider this question comes to us through observation and mathematical constructs.

You believe, if I'm not mistaken, that the object doesn't actually shrink, it only appears to shrink. What observational evidence or mathematical evidence do we have to support that conclusion?

Bare in mind, I'm not attacking you with this question, I am only presenting you with a thought experiment for us to think about.

We have the evidence that if the actual object shrunk in length, that would be compression of the mass, it would then expand in height, applied force is needed for compression, space offers no resistance to motion.
i,e cars contract in length when they hit  a wall fast

i.e for something to contract the rear would have to be travelling faster than the front

Or vice versus and the front would have to slow down

« Last Edit: 10/02/2016 21:47:39 by Thebox »

#### Ethos_

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##### Re: Is distance an absolute invariant?
« Reply #207 on: 10/02/2016 21:47:28 »

We have the evidence that if the actual object shrunk in length, that would be compression of the mass, it would then expand in height, applied force is needed for compression, space offers no resistance to motion.

I understand your point Mr. Box and that would be the logical assumption. But remember, reality is not always logical and we need to look for evidence other than just logical assumption.

Leaving this question for a moment, how about time dilation. Can we agree that time dilation actually takes place? Taking into consideration that our GPS system must account for this factor to accurately map our earth and account for the time differences.

#### Space Flow

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##### Re: Is distance an absolute invariant?
« Reply #208 on: 10/02/2016 21:49:38 »
I think if the observer spun  with an orbiting object there would be no contraction.

Thebox, your eyes when you turn with the satellite are describing a circle that has a radius, circumference and speed. Those qualities when compared with the satellite's radius, circumference and speed, are not the same.
Whenever there is an observed difference in speed there will be an observed difference in time and length.
Whether you want to call that real or just illusionary is at this stage up to you. But the effect is there and it is measurable.
Maybe the reason you have not understood what we are saying so far is this "observation".
You see and I think you are finally taking the first steps to understanding, "Relativity" is about what is observed and measured from one reference frame to another. It does not claim that any change can ever be seen to one's own frame. No matter what you believe is causing those observations to be what they are, if you don't acknowledge them and make corrections for them, then two different frames could never coherently communicate.

Having said all that I better add for precision's sake that in your picture there are two effects in play and they are working against each other to give you the observations that you will measure and have to correct for.
One is the difference in observed speed and the other is the difference in the speed of the flowing spacetime, due to the inverse square law and the satellite being further from the centre of the system (Gravity).
Change the rate of time of what?
Not of what.
Change of rate of time. (See that character after the word time? That is a full stop.)

#### Thebox

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##### Re: Is distance an absolute invariant?
« Reply #209 on: 10/02/2016 21:52:09 »

We have the evidence that if the actual object shrunk in length, that would be compression of the mass, it would then expand in height, applied force is needed for compression, space offers no resistance to motion.

I understand your point Mr. Box and that would be the logical assumption. But remember, reality is not always logical and we need to look for evidence other than just logical assumption.

Leaving this question for a moment, how about time dilation. Can we agree that time dilation actually takes place? Taking into consideration that our GPS system must account for this factor to accurately map our earth and account for the time differences.

I can agree that there is a dilation of the timing mechanism synchronisation to gravity of mass that is situated in a timeless 5th dimension of space-time.

Taking into consideration that anything after 0 is history  and all mass including the satellites are travelling through simultaneous time that is timeless.

#### Thebox

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##### Re: Is distance an absolute invariant?
« Reply #210 on: 10/02/2016 21:54:50 »

Not of what.
Change of rate of time. (See that character after the word time? That is a full stop.)

Yes! change of time of what?

#### timey

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##### Re: Is distance an absolute invariant?
« Reply #211 on: 10/02/2016 21:57:07 »
Surely the special relativity effects only apply to the accelerated reference frame?
Timey, SR does not in any way address or describe any accelerated frame.
SR is only about constant relative speed between observers. It is a good way of describing relativistic time dilation and length contraction "principles" but does not actually apply to any known real situation in the Universe.
That is the reason that Einstein kept on working on and finally brought out GR as a way of applying the concepts that SR introduced to real world scenarios.

OK, I'm following you.  But... what I am trying to understand is 'how' the maths from the concepts of SR: ie: length contraction for the observer, and distance contraction, plus velocity related time dilation for the accelerated frame, mesh with the general relativity time dilation considerations and the stretching of spacetime.  They appear to be entwined indistinguishably within the GR field equations amongst some very complex geometrical considerations.  I'd like to understand.

#### Space Flow

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##### Re: Is distance an absolute invariant?
« Reply #212 on: 10/02/2016 21:59:31 »
We have the evidence that if the actual object shrunk in length, that would be compression of the mass, it would then expand in height, applied force is needed for compression, space offers no resistance to motion.
i,e cars contract in length when they hit  a wall fast

i.e for something to contract the rear would have to be travelling faster than the front
Here you are making the classic mistake of visualising the length contraction as something that matter might do within the space it occupies, therefore occupying less space.
That is not the effect we observe or describe.
It is the contraction of the spacetime itself. Matter just keeps occupying the same amount of space it always has. It appears to contract because the space it occupies appears to contract.
Remember to focus on the word "Appears".
It is always how something behaves relatively when viewed from a reference frame other than its own.

#### Thebox

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##### Re: Is distance an absolute invariant?
« Reply #213 on: 10/02/2016 22:00:53 »
We have the evidence that if the actual object shrunk in length, that would be compression of the mass, it would then expand in height, applied force is needed for compression, space offers no resistance to motion.
i,e cars contract in length when they hit  a wall fast

i.e for something to contract the rear would have to be travelling faster than the front
Here you are making the classic mistake of visualising the length contraction as something that matter might do within the space it occupies, therefore occupying less space.
That is not the effect we observe or describe.
It is the contraction of the spacetime itself. Matter just keeps occupying the same amount of space it always has. It appears to contract because the space it occupies appears to contract.
Remember to focus on the word "Appears".
It is always how something behaves relatively when viewed from a reference frame other than its own.

You have not read what Ethos asked.  quote ethos - ''You believe, if I'm not mistaken, that the object doesn't actually shrink, it only appears to shrink. What observational evidence or mathematical evidence do we have to support that conclusion?''

#### Space Flow

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##### Re: Is distance an absolute invariant?
« Reply #214 on: 10/02/2016 22:02:07 »
Yes! change of time of what?

Hang on I did answer the question.
Quote from: Thebox on Today at 08:36:01
Change the rate of time of what?
Not of what.
Change of rate of time. (See that character after the word time? That is a full stop.)

#### Thebox

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##### Re: Is distance an absolute invariant?
« Reply #215 on: 10/02/2016 22:04:26 »
Yes! change of time of what?

Hang on I did answer the question.
Quote from: Thebox on Today at 08:36:01
Change the rate of time of what?
Not of what.
Change of rate of time. (See that character after the word time? That is a full stop.)

that is an incompleteness answer, I may have to quote Gobel.

Are you sure the answer is not  - a change in the rate of time of the caesium atom?

and should time not be timing or synchronisation?

a change in the rate of synchronisation of the caesium atom relative to a gravitational field
« Last Edit: 10/02/2016 22:07:06 by Thebox »

#### Space Flow

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##### Re: Is distance an absolute invariant?
« Reply #216 on: 10/02/2016 22:06:38 »
Is that not what you keep asking for?
As far as anyone else's understanding if I address them I will do so by quoting them.

#### Thebox

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##### Re: Is distance an absolute invariant?
« Reply #217 on: 10/02/2016 22:09:02 »
Is that not what you keep asking for?
As far as anyone else's understanding if I address them I will do so by quoting them.

Yes I understand, But Ethos asked me a question about an actual object and asked how we could disprove the actual object shrank, which I answered.  You read it wrong and presumed I was saying an object shrunk .

#### Space Flow

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##### Re: Is distance an absolute invariant?
« Reply #218 on: 10/02/2016 22:13:07 »
that is an incompleteness answer, I may have to quote Gobel.

Are you sure the answer is not  - a change in the rate of time of the caesium atom?

and should time not say timing or synchronisation?
As you may have noticed and are obviously choosing to ignore the fact, I did not mention caesium atom or any matter based anything neither did I mention timing or synchronisation.
If that was what I meant, than that is what I would have said.
I am answering your direct question with a direct and complete answer and would appreciate it if you did not try to assume I ever mean anything other than what I say. I have a wife who has that kind of thing more than adequately covered.

#### Space Flow

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##### Re: Is distance an absolute invariant?
« Reply #219 on: 10/02/2016 22:19:22 »
Is that not what you keep asking for?
As far as anyone else's understanding if I address them I will do so by quoting them.

Yes I understand, But Ethos asked me a question about an actual object and asked how we could disprove the actual object shrank, which I answered.  You read it wrong and presumed I was saying an object shrunk .
If I took an answer of yours to someone else out of context, I apologize.
I am concentrating on you and the subject matter of this post.
Therefore any reference to contraction I took to be a reference to contraction as described by relativity.
I will check out what others have said at a more leisurely time and address any issues I perceive in their comments then. Right now it's about you.

#### Ethos_

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##### Re: Is distance an absolute invariant?
« Reply #220 on: 10/02/2016 22:21:54 »

I can agree that there is a dilation of the timing mechanism synchronisation to gravity of mass that is situated in a timeless 5th dimension of space-time.

As I understand your terminology, you're saying you agree that there is a time dilation of the timing device relative to the observer.

I'm going to bow out for a while, things are getting a little too congested with so many interested parties weighing in. One thought before I go however:

If the pace of time on that time dilated clock records a slowing down,  can't one also visualize the compression of length due to Lorentz contraction?

And the reason for that connection comes from how science views space and time. The current understanding regarding these two identities is; They can not be totally separated one from the other. It's the reason you'll see the term "space/time" spoken of so often. Today, science views space/time as more or less a single entity.

More on this later.......................................Ethos

« Last Edit: 10/02/2016 22:30:55 by Ethos_ »

#### Thebox

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##### Re: Is distance an absolute invariant?
« Reply #221 on: 10/02/2016 22:22:58 »
that is an incompleteness answer, I may have to quote Gobel.

Are you sure the answer is not  - a change in the rate of time of the caesium atom?

and should time not say timing or synchronisation?
As you may have noticed and are obviously choosing to ignore the fact, I did not mention caesium atom or any matter based anything neither did I mention timing or synchronisation.
If that was what I meant, than that is what I would have said.
I am answering your direct question with a direct and complete answer and would appreciate it if you did not try to assume I ever mean anything other than what I say. I have a wife who has that kind of thing more than adequately covered.

Lol good answer , but you know and I know very well what we refer to when talking time dilation, and relative motion to a gravitational field.

I will rephrase, how do you know that there is a change in time?

By what method ?

A change in the rate of synchronisation of the caesium atom relative to a gravitational field, notice I have no need to mention time or even consider time with this one statement?

I would have to consider timing and timing synchronisation for sure, But I  am certain anything after 0 is history, and I  can not alter the rate of 0 with any thought experiment.

#### Thebox

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##### Re: Is distance an absolute invariant?
« Reply #222 on: 10/02/2016 22:33:59 »

I can agree that there is a dilation of the timing mechanism synchronisation to gravity of mass that is situated in a timeless 5th dimension of space-time.

As I understand your terminology, you're saying you agree that there is a time dilation of the timing device relative to the observer.

I'm going to bow out for a while, things are getting a little too congested with so many interested parties weighing in. One thought before I go however:

If the pace of time on that time dilated clock records a slowing down,  can't one also visualize the compression of length due to Lorentz contraction. And the reason for that connection comes from how science views space and time. The current understanding regarding these two identities is; They can not be totally separated one from the other. It's the reason you'll see the term "space/time" spoken of so often. Today, science views space/time as more or less a single entity.

More on this later.......................................Ethos

Thank you for the conversation, and yes one  has to compare length contraction with time dilation, and yes the way science view space-time is weird imo, I observe people sort of have two views, some people seem to explain it as light, and others explain it as minkowski space-time, the interwoven manifold, but people miss the fact that space-time meaning the space between masses, is a virtual representation of time and for vector use.

The actual time in space is not existing until the space is occupied by something that needs, a need for time. i.e us

Consider this, the past , the now, the future all move with the earth and leave no trace of history in the path behind it.

#### timey

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##### Re: Is distance an absolute invariant?
« Reply #223 on: 10/02/2016 22:36:18 »
I would have to consider timing and timing synchronisation for sure, But I  am certain anything after 0 is history, and I  can not alter the rate of 0 with any thought experiment.

Box, you are talking about the here and now.  You cannot measure the here and now.

Space Flow... I also like the wife comment (chuckle)
« Last Edit: 10/02/2016 22:42:17 by timey »

#### Thebox

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##### Re: Is distance an absolute invariant?
« Reply #224 on: 10/02/2016 22:38:29 »
Box, you are talking about the here and now.  You cannot measure the here and now.

Space Flow... I also like the wife comment (chuckle)

So you must agree that any effect of a measurement can not affect the here and now?

You can not measure the future either, you can only record the past .

#### The Naked Scientists Forum

##### Re: Is distance an absolute invariant?
« Reply #224 on: 10/02/2016 22:38:29 »