Is the speed of light always 299 792 458 m / s

[Dale]

Yes this is true…
But on the other hand, our reality begins (or end, - if you prefer) where the photons reality begin. From the perspective of the photon there can (mathematically) not exist distances, time, and I guess even not space, - it must be nothing.
To be extreme “reality” as a whole includes nothing and everything between nothing and everything, depending on space-time 'perspective'
It is at least attempting to talk about “different space-time realities” – because "they" can be so diffrent, - but is as you point out also not perfect to do so, - because "these" are not clear separated but rather “one” reality - ("separated" by time, - at least photons, neutrinos etc. seems to be) and as you see now I contradict what I Just wrote. .

This is so self contradictory that it doesn't even rise to the level of philosophy, let alone science.

We can measure a photon existence, and the speed of it, - but seen from the photons own perspective, it doesn’t exist (in space and time) because by the speed c, space-time doesn’t exist.

https://www.physicsforums.com/showthread.php?t=511170

As I see it, I cannot see any direct experiment is possible, to reveal that.
As I wrote; only logical indirect conclusion.
How can A prove to B that his definition of one meter is "correct" (meaning universal).
The problem is A is still in top of the skyscraper and B in the cellar.
Where must the comparison take place?
I simply have no idea, and don’t think such experiments are done already.
Should I be wrong I would like to hear about it.

Here I post, for reference, a relevant answer for comparing clocks from our previous conversation. With a small amount of thought you should be able to turn those into methods for comparing distances instead.

http://74.86.200.109/showpost.php?p=3783933&postcount=151

The result you get, as I have said many times, depends on the method of comparison, and GR can correctly predict the result for each method.

 

[Bjarne]

This is so self contradictory that it doesn't even rise to the level of philosophy, let alone science.

It was intended. There was no conclusion, - it should not make sense.

https://www.physicsforums.com/showthread.php?t=511170

Which mean a mathematical "reality" contradict logical rational thinking, - and doesn’t make logical sense (?). I can only agree to that.

Here I post, for reference, a relevant answer for comparing clocks from our previous conversation. With a small amount of thought you should be able to turn those into methods for comparing distances instead.
https://www.physicsforums.com/showthread.php?t=511170... (copy past)...>>
Sure, I can see at least 4 ways to compare two distant clocks:
A) Broadcast a reference signal, measure the frequency of the signal locally at each clock
B) Take a reference clock, physically transport it from one clock to the other and measure the rate of the reference locally at each clock
C) Agree on a standard physics experiment as a reference, perform it locally at each clock and measure the time for the experiment
D) Agree on an astronomical reference and measure the time for the astronomical reference locally

The beauty of GR is that it is a single law of physics which explains A, B, C, and D all together

I have read it long ago.
These experiments are already (more or less) done, and with reference to the context of this thread to my opinion only “indirect scientific evidence”.
I don’t think this is enough to finally determinate, whether the definition of 1 meter is universal or not? – What do you think?

The result you get, as I have said many times, depends on the method of comparison, and GR can correctly predict the result for each method.

Right
But what about the question; is the definition of 1 meter (based on the current definition of 1 second) universal or not? – Or must the definition be “floating” and only true when it is be based on a relative local stretching or contracting “second” ? – What exactly do you think.

 

[HomogenousCow]

This thread is very lacking in any quantitative discussion, and most of it is talk of meta-physical ideas such as "reality" and what not.

 

[Drakkith]

But what about the question; is the definition of 1 meter (based on the current definition of 1 second) universal or not? – Or must the definition be “floating” and only true when it is be based on a relative local stretching or contracting “second” ? – What exactly do you think.

I think every time you measure a meter it will be the same length. An objects physical dimensions may change from the point of view of your frame of reference due to relativistic factors, but you will never measure a meter as being different.

 

[Bjarne]

This thread is very lacking in any quantitative discussion, and most of it is talk of meta-physical ideas such as "reality" and what not.

The right brain sees the forest, but not the (quantitative) trees (it is not important), - the left brain see the trees very detailed, but not the forest. The confused brain that try to see the forest cannot because there are too many (quantitative) trees.

 

[Bjarne]

I think every time you measure a meter it will be the same length. An objects physical dimensions may change from the point of view of your frame of reference due to relativistic factors, but you will never measure a meter as being different.

Yes this is what seems to be at least very logical, (based on holistic thinking).

 

[Vanadium 50]

This thread is very lacking in any quantitative discussion, and most of it is talk of meta-physical ideas such as "reality" and what not.

Exactly. And every time it starts going in the direction of science, one of the members here pushes it back.

Thread closed.