What is the difference between a preferred state of rest and a preferred state of velocity?

[Simplico]

As current theories are leading to a logical cul-de-sac, I just think it would be a good idea to go back to the start and try to look at things from a different perspective. Starting with the question of what everything is moving relative to.  The current idea is an inertial frame of reference, previously it was the stationary earth, and for a while the fixed stars. An inertial frame of reference is considered to be a place where the laws of physics are at their simplest. But if we don't know what the laws of physics are, how can we tell when they are at their simplest? It could well be in a hundred years time people will smile at the ideas we have about what bodies move relative to. I suppose I should have made this more clear in my post, but my point is as we do not understand the universe down the path we have been on, maybe we should look for another path.

The theory of SR. I didn't make a good job of it, but I was going to point out that ideas of what bodies are moving relative to have changed over the centuries. Newton was one of the greatest scientists of all time, but he had the idea that you could use the 'fixed stars' as a reference point for motion. The idea of a fixed velocity has it's merits, but also leads to logical inconsistencies (division by zero) and objects that have mass but no size (black holes).

[swansont]

8 minutes ago, Simplico said:

As current theories are leading to a logical cul-de-sac,

They are? 

8 minutes ago, Simplico said:

I just think it would be a good idea to go back to the start and try to look at things from a different perspective. Starting with the question of what everything is moving relative to.  The current idea is an inertial frame of reference, previously it was the stationary earth, and for a while the fixed stars. An inertial frame of reference is considered to be a place where the laws of physics are at their simplest. But if we don't know what the laws of physics are, how can we tell when they are at their simplest?

We do know what some (most) of the laws of physics are. The ones that are readily testable, especially.

8 minutes ago, Simplico said:

It could well be in a hundred years time people will smile at the ideas we have about what bodies move relative to. I suppose I should have made this more clear in my post, but my point is as we do not understand the universe down the path we have been on, maybe we should look for another path.

Asserted without evidence. 

 

[Strange]

11 minutes ago, Simplico said:

As current theories are leading to a logical cul-de-sac

Are they? Can you provide some evidence of this?

12 minutes ago, Simplico said:

Starting with the question of what everything is moving relative to. 

People have looked (and continue to look) for evidence of an absolute reference or, more generally, violations of Lorentz invariance. So far, no evidence supports this idea.

11 minutes ago, Simplico said:

An inertial frame of reference is considered to be a place where the laws of physics are at their simplest.

Citation needed.

12 minutes ago, Simplico said:

Newton was one of the greatest scientists of all time, but he had the idea that you could use the 'fixed stars' as a reference point for motion.

And indeed you can. But you can use anything else (and I'm sure Newton knew that).

14 minutes ago, Simplico said:

The idea of a fixed velocity has it's merits, but also leads to logical inconsistencies (division by zero)

Huh?

14 minutes ago, Simplico said:

and objects that have mass but no size (black holes).

Black holes have size. The only ones we know about are pretty big.

[studiot]

30 minutes ago, Simplico said:

As current theories are leading to a logical cul-de-sac, I just think it would be a good idea to go back to the start and try to look at things from a different perspective. Starting with the question of what everything is moving relative to.  The current idea is an inertial frame of reference, previously it was the stationary earth, and for a while the fixed stars. An inertial frame of reference is considered to be a place where the laws of physics are at their simplest. But if we don't know what the laws of physics are, how can we tell when they are at their simplest? It could well be in a hundred years time people will smile at the ideas we have about what bodies move relative to. I suppose I should have made this more clear in my post, but my point is as we do not understand the universe down the path we have been on, maybe we should look for another path.

The theory of SR. I didn't make a good job of it, but I was going to point out that ideas of what bodies are moving relative to have changed over the centuries. Newton was one of the greatest scientists of all time, but he had the idea that you could use the 'fixed stars' as a reference point for motion. The idea of a fixed velocity has it's merits, but also leads to logical inconsistencies (division by zero) and objects that have mass but no size (black holes).

If these assertions of yours come from your studies, you have been seriously mislead.

 

In particular concerning relativity, you can use anything you like as a reference point.

So yes you could use the 'fixed stars'.

But the point of relativity is that you will obtain a different answer if you refer to a different reference point.

Newton knew this, although the credit for first stating this in a form we can recognise is given to Galileo by modern reference to Galilean relativity.

Einstein added something extra with special relativity, giving special status to the speed of light.

 

Actually the history of relativity goes back at least 5000 years to the ancient civilizations of the Nile and the fertile crescent. 
But it was a very different concept then.

Even in Galileo's day there was no modern concept of velocity or even speed.
They simply had no means to measure speed in anything other than comparative terms.
But comparison is a form of relativity.
So they knew that a dog can run faster than a man, but had no means to put numbers to it by measurement.

We can discuss the development of relativity from the earliest times if you like.

 

 

Edited May 24, 2018 by studiot

[beecee]

14 minutes ago, Simplico said:

The theory of SR. I didn't make a good job of it, but I was going to point out that ideas of what bodies are moving relative to have changed over the centuries. Newton was one of the greatest scientists of all time, but he had the idea that you could use the 'fixed stars' as a reference point for motion. The idea of a fixed velocity has it's merits, but also leads to logical inconsistencies (division by zero) and objects that have mass but no size (black holes).

Total rubbish. We have plenty of evidence for SR, and really, the actual merits of science and particularly cosmology, is that it is able to change based on new observational data, and as our technologies improve and advance. We are able to make some outstanding observations and formulate models on the universe, up to at least 10-43 seconds after the BB event. Science has educated humanity and pushed into near oblivion the need for any magical spaghetti monster. The few stragglers and gullible left that still align to the book of myths are brainwashed beyond redemption, and no amount of science and logical answers will ever turn them. Thank Christ though that they are a dying breed.

[StringJunky]

43 minutes ago, beecee said:

Total rubbish. We have plenty of evidence for SR, and really, the actual merits of science and particularly cosmology, is that it is able to change based on new observational data, and as our technologies improve and advance. We are able to make some outstanding observations and formulate models on the universe, up to at least 10-43 seconds after the BB event. Science has educated humanity and pushed into near oblivion the need for any magical spaghetti monster. The few stragglers and gullible left that still align to the book of myths are brainwashed beyond redemption, and no amount of science and logical answers will ever turn them. Thank Christ though that they are a dying breed.

I think the "few" are actually many in the US :

https://en.wikipedia.org/wiki/Level_of_support_for_evolution#/media/File:Views_on_Evolution.svg

Edited May 24, 2018 by StringJunky

[Eise]

13 hours ago, Simplico said:

The concept of the earth being flat is very useful for measuring or calculating short distances. It just doesn't represent reality.

It does represent reality. Just not precisely. But there is no reason for house builders to account for the earth's real form. Every representation of reality leaves something out.

But I already said that frames of reference do not exist at all in reality. A frame of reference is like a coordinate system you use to make calculations. There are no coordinate systems in nature. But if the calculations are correct (e.g. you can predict the outcome of experiments with it), then you are methodologically justified to use them. And there is a very simple definition of what inertial frames are: all objects that stand still in relation to each other and no force works on any of these objects are said to belong to the same frame of reference. But there is no 'natural inertial frame', let alone one that is absolutely at rest. And as told you by several others here, light always moves with the same speed in any inertial frame, so it is no substitute for any 'preferred state of rest'.

Further you underestimate how fundamental special relativity is. Any theory in physics that claims to be universal, must be consistent with special relativity, i.e. its laws of nature must be Lorentz-invariant. To give an example: the first formulations of quantum mechanics were not Lorentz-invariant. Dirac however did the job of formulating QM in a Lorentz-invariant way. But two predictions rolled out of it: that electrons have spin, and that they have anti-particles. Both were confirmed empirically.

So in summary: you can derive special relativity without referring to inertial frames (relative velocities between objects suffice); and special relativity belongs to the bones of all physics, and is also tested to the bones. So what is the 'cul de sac' you are talking about??

 

[YaDinghus]

On 5/25/2018 at 12:37 AM, StringJunky said:

I think the "few" are actually many in the US :

https://en.wikipedia.org/wiki/Level_of_support_for_evolution#/media/File:Views_on_Evolution.svg

Odd. It seems that the percentage of people saying "No" or "Not sure" in Germany are pretty close to the representation of the AfD, Germany's most successful right-wing party, in the Bundestag. Coinkidoinky?

 

As far as I know, GR makes a fundamental distinction between inertial systems (no net force) and accelerating systems (net force). On earth, it's not easy to observe inertial systems, with all the friction going on, plus we're running around on a spinning, tilted, tumbling mudball on a slightly eccentric orbit around our parent gigantic fireball, which makes the achievements of science all the more awesome!

[koti]

On 25.05.2018 at 12:37 AM, StringJunky said:

I think the "few" are actually many in the US :

https://en.wikipedia.org/wiki/Level_of_support_for_evolution#/media/File:Views_on_Evolution.svg

This is graph is horrible. If this wasn’t in Relativity I’d opt for us to launch a country with Phi the king, Janus, swansont, Mordred, Arete, CharonY and a few others the brains and TenOz and Dimreepr keeping guard. I’d be making flashlights ofcourse as they would be essential ofcourse. But this is in Realativity so I won’t. 

[mistermack]

What I struggle with isn't the concept that the laws of special relativity work equally well in all inertial frames. What allows that to happen is the fact that time passes at a different rate in every inertial frame. i.e. every observer MEASURES the speed of light at a fixed value, because every inertial observer has time passing at a different rate. 

What niggles at me though, is that, if every observer experiences time at a different rate, then time passes faster for some, and slower for others. There must be a top limit, and a bottom limit, for the rate of time. I get the bottom limit is for any inertial frame travelling at a steady rate of c. Time stops altogether, and matter cannot reach that speed. 

But what is the top limit for time. In what frame does a stationary clock tick the fastest? Is there a frame where a clock can tick infinitely fast, or is there a limit? And if there is a limit, there must be a preferred frame, where a clock ticks at it's max.

Is it that it's impossible to identify that frame, or is it that it doesn't exist?

On a slightly different note, people are starting to use the rest frame of the cosmic microwave background radiation as a preferred frame, since someone actually got a fix on it. https://physics.stackexchange.com/questions/25928/is-the-cmb-rest-frame-special-where-does-it-come-from   

 

 

[swansont]

1 hour ago, mistermack said:

 But what is the top limit for time. In what frame does a stationary clock tick the fastest? Is there a frame where a clock can tick infinitely fast, or is there a limit? And if there is a limit, there must be a preferred frame, where a clock ticks at it's max.

In its own frame. Moving clocks run slow relative to that. 

Quote

Is it that it's impossible to identify that frame, or is it that it doesn't exist?

It's always relative. Every observer see their own clock as running fastest

Quote

On a slightly different note, people are starting to use the rest frame of the cosmic microwave background radiation as a preferred frame, since someone actually got a fix on it. https://physics.stackexchange.com/questions/25928/is-the-cmb-rest-frame-special-where-does-it-come-from   

There's a difference between a preferred frame meaning an absolute frame, i.e. one you can identify because physics works correctly in that frame, vs. preferred as in it's convenient using that as a reference. The earth, for example, is a convenient frame for many problems, but it is not an absolute frame.

[mistermack]

1 hour ago, swansont said:

In its own frame. Moving clocks run slow relative to that. 

It's always relative. Every observer see their own clock as running fastest

There's a difference between a preferred frame meaning an absolute frame, i.e. one you can identify because physics works correctly in that frame, vs. preferred as in it's convenient using that as a reference. The earth, for example, is a convenient frame for many problems, but it is not an absolute frame.

That's the accepted working version, and there's nothing wrong with it. What I'm getting at is the reality, lurking behind the relativity.

Apologies for the copy and paste, but this from the wikipedia page on the twin paradox covers what I was getting at : 

https://en.wikipedia.org/wiki/Twin_paradox#No_twin_paradox_in_an_absolute_frame_of_reference     

"

No twin paradox in an absolute frame of reference[edit]

Einstein's conclusion of an actual difference in registered clock times (or aging) between reunited parties caused Paul Langevin to posit an actual, albeit experimentally undetectable, absolute frame of reference:

In 1911, Langevin wrote: "A uniform translation in the aether has no experimental sense. But because of this it should not be concluded, as has sometimes happened prematurely, that the concept of aether must be abandoned, that the aether is non-existent and inaccessible to experiment. Only a uniform velocity relative to it cannot be detected, but any change of velocity .. has an absolute sense."^[32]

In 1913, Henri Poincaré posthumous Last Essays were published and there he had restated his position: "Today some physicists want to adopt a new convention. It is not that they are constrained to do so; they consider this new convention more convenient; that is all. And those who are not of this opinion can legitimately retain the old one."."^[33]

In the relativity of Poincaré and Hendrik Lorentz, which assumes an absolute (though experimentally indiscernable) frame of reference, no twin paradox arises due to the fact that clock slowing (along with length contraction and velocity) is regarded as an actuality, hence the actual time differential between the reunited clocks.

That interpretation of relativity, which John A. Wheeler calls "ether theory B (length contraction plus time contraction)", did not gain as much traction as Einstein's, which simply disregarded any deeper reality behind the symmetrical measurements across inertial frames. There is no physical test which distinguishes one interpretation from the other.^[34]

More recently (in 2005), Robert B. Laughlin (Physics Nobel Laureate, Stanford University), wrote about the nature of space:

"It is ironic that Einstein's most creative work, the general theory of relativity, should boil down to conceptualizing space as a medium when his original premise [in special relativity] was that no such medium existed . . . The word 'ether' has extremely negative connotations in theoretical physics because of its past association with opposition to relativity. This is unfortunate because, stripped of these connotations, it rather nicely captures the way most physicists actually think about the vacuum. . . . Relativity actually says nothing about the existence or nonexistence of matter pervading the universe, only that any such matter must have relativistic symmetry." (i.e., as measured)."^[35]

A. P. French writes, in Special Relativity:

"Note, though, that we are appealing to the reality of A's acceleration, and to the observability of the inertial forces associated with it. Would such effects as the twin paradox exist if the framework of fixed stars and distant galaxies were not there? Most physicists would say no. Our ultimate definition of an inertial frame may indeed be that it is a frame having zero acceleration with respect to the matter of the universe at large.")."^[36]

[Strange]

1 hour ago, mistermack said:

That's the accepted working version, and there's nothing wrong with it. What I'm getting at is the reality, lurking behind the relativity.

That is the reality (or as close as science ever gets).

1 hour ago, mistermack said:

Apologies for the copy and paste, but this from the wikipedia page on the twin paradox covers what I was getting at :

That covers quite a range of views. Do you have any specific comments on it.

[mistermack]

14 minutes ago, Strange said:

That is the reality (or as close as science ever gets).

That covers quite a range of views. Do you have any specific comments on it.

When I mentioned reality, I was referring to this bit " That interpretation of relativity, which John A. Wheeler calls "ether theory B (length contraction plus time contraction)", did not gain as much traction as Einstein's, which simply disregarded any deeper reality behind the symmetrical measurements across inertial frames. There is no physical test which distinguishes one interpretation from the other.^[34]    

 The quote says it better than I could.  The point is, if there was a "real" inertial frame, it would be indistinguishable from all others. But what about the total energy of the universe? Is it real or relative? If you take the total energy of the Earth, it depends on what inertial frame you choose. There is only one, which gives the absolute minimum value, and that's the one in which the Earth is stationary.

If you scale that up to the Universe, surely there must be an equivalent frame, in which the total energy of the Universe is the minimum. 

That must be a frame in which the Universe can be considered at rest, as a whole. Any other frame is adding enormous kinetic energy to the universe.

[studiot]

42 minutes ago, mistermack said:

That must be a frame in which the Universe can be considered at rest, as a whole. Any other frame is adding enormous kinetic energy to the universe.

 

This is ill founded.

 

The universe is not 'in motion' nor yet 'at rest'.

Where do you think the universe might be going to or have come from, or alternatively staying put at?

[mistermack]

15 minutes ago, studiot said:

 

This is ill founded.

 

The universe is not 'in motion' nor yet 'at rest'.

Where do you think the universe might be going to or have come from, or alternatively staying put at?

If all inertial frames are valid, then the universe must surely be all of those things ?

[studiot]

But it is not itself moving as a whole.

 

Moving in this case means translating (as a whole) not that different parts of it are in motion relative to each other.

Inerterial frames are abstract objects. It is a matter of opinion whether you count them as part of the universe or not.

[Markus Hanke]

16 hours ago, mistermack said:

What allows that to happen is the fact that time passes at a different rate in every inertial frame.

That is not actually the right way to look at it. Time passes at exactly the same rate (1 second per second) in all reference frames, including non-inertial ones. The only thing that changes is the relationship between frames in spacetime - and that is what time dilation and length contraction are: a relationship between frames. They are not local phenomena, but global ones.

16 hours ago, mistermack said:

In what frame does a stationary clock tick the fastest?

The longest possible amount of proper time between two events is always traced out by a geodesic in that spacetime. In other words - a locally inertial frame in free fall.

[mistermack]

I think that the point being made in the wikipedia article that I pasted was that relativity certainly works in all frames, but that doesn't eliminate the possibility of one frame representing a deeper reality. It's just that there is no way of identifying that frame. They are saying that while there is no ether that matter travels through, there is no reason to suppose that space time has no substance, and it's looking more and more likely that it has. It's just that it can't be observed or detected in any way. Unless you adhere to the river model which models gravity as a flow of space time. 

If space time does move about in gravitational fields, then there could be no universal preferred frame, but a free falling object in a gravitational field, that's moving at the escape velocity of that field (in the opposite direction of escape), is motionless in the local preferred frame. The closest you could get to nailing down a universal preferred frame would be to take the entire universe, and compare your motion to that. Maybe that's what the CMBR gives, something independent of local conditions.

Edited June 11, 2018 by mistermack

[Markus Hanke]

1 minute ago, mistermack said:

It's just that it can't be observed or detected in any way.

If it cannot be observed or detected, then it has no impact whatsoever on the laws of physics - meaning it is irrelevant to physics as a discipline. Its existence or non-existence thus becomes mere speculation.

4 minutes ago, mistermack said:

If space time does move about in gravitational fields

This does not make any sense as a concept, because gravity is a geometric property of spacetime.

[mistermack]

1 minute ago, Markus Hanke said:

If it cannot be observed or detected, then it has no impact whatsoever on the laws of physics - meaning it is irrelevant to physics as a discipline. Its existence or non-existence thus becomes mere speculation.

Yes of course. Whether that's the permanent case or not remains to be seen.

[swansont]

16 minutes ago, mistermack said:

I think that the point being made in the wikipedia article that I pasted was that relativity certainly works in all frames, but that doesn't eliminate the possibility of one frame representing a deeper reality. It's just that there is no way of identifying that frame.

Which means there's no way to tell if you are in that frame. 

How is that different from saying the frame doesn't exist? It's like saying unicorns exist, but they are not only invisible, there is no way to interact with them, in any way.

16 minutes ago, mistermack said:

They are saying that while there is no ether that matter travels through, there is no reason to suppose that space time has no substance, and it's looking more and more likely that it has. It's just that it can't be observed or detected in any way.

So it might as well not exist.

If you want to argue that it still does, despite no evidence or possibility of getting evidence, then it becomes (at best) a philosophical argument.

[mistermack]

7 minutes ago, swansont said:

So it might as well not exist.

If you want to argue that it still does, despite no evidence or possibility of getting evidence, then it becomes (at best) a philosophical argument.

OK, but I'm in good company. This again from Robert Laughlin : 

More recently (in 2005), Robert B. Laughlin (Physics Nobel Laureate, Stanford University), wrote about the nature of space:

"It is ironic that Einstein's most creative work, the general theory of relativity, should boil down to conceptualizing space as a medium when his original premise [in special relativity] was that no such medium existed . . . The word 'ether' has extremely negative connotations in theoretical physics because of its past association with opposition to relativity. This is unfortunate because, stripped of these connotations, it rather nicely captures the way most physicists actually think about the vacuum. . . . Relativity actually says nothing about the existence or nonexistence of matter pervading the universe, only that any such matter must have relativistic symmetry." (i.e., as measured)."^[35]

Of course it's speculation. What's wrong with that? If nobody speculated, everything would stop dead. It's hopefully relevant to the topic of the thread.

 

[J.C.MacSwell]

19 minutes ago, swansont said:

Which means there's no way to tell if you are in that frame. 

How is that different from saying the frame doesn't exist? It's like saying unicorns exist, but they are not only invisible, there is no way to interact with them, in any way.

So it might as well not exist.

If you want to argue that it still does, despite no evidence or possibility of getting evidence, then it becomes (at best) a philosophical argument.

Surely if you do not know for certain something does or does not exist, claiming that it doesn't is not on the same standing as claiming you don't know, or claiming that the possibility has not been eliminated.

Edited June 11, 2018 by J.C.MacSwell

[swansont]

37 minutes ago, J.C.MacSwell said:

Surely if you do not know for certain something does or does not exist, claiming that it doesn't is not on the same standing as claiming you don't know, or claiming that the possibility has not been eliminated.

It's more than not knowing, though. There is no way, even in principle, to test to see if it exists. It's not that there is no evidence, it's that there can be no evidence. It has zero impact on physics.

 

43 minutes ago, mistermack said:

OK, but I'm in good company. This again from Robert Laughlin : 

More recently (in 2005), Robert B. Laughlin (Physics Nobel Laureate, Stanford University), wrote about the nature of space:

"It is ironic that Einstein's most creative work, the general theory of relativity, should boil down to conceptualizing space as a medium when his original premise [in special relativity] was that no such medium existed . . . The word 'ether' has extremely negative connotations in theoretical physics because of its past association with opposition to relativity. This is unfortunate because, stripped of these connotations, it rather nicely captures the way most physicists actually think about the vacuum. . . . Relativity actually says nothing about the existence or nonexistence of matter pervading the universe, only that any such matter must have relativistic symmetry." (i.e., as measured)."^[35]

Of course it's speculation. What's wrong with that? If nobody speculated, everything would stop dead. It's hopefully relevant to the topic of the thread.

 

These are not the same arguments. Relativistic symmetry = no preferred frame. You are talking about a frame, and Laughlin is talking about matter.

Your very mention of "deeper reality" points toward metaphysics, not physics.