[jsaldea12 (OP)]

Thank you Moderator Evan for being understanding.but permit me to post correct  different title, re- :"Why speed of light is constant at 186,000 miles/sec.,  forward, backward, sideward" It is like this: all space,  outer space and space on earth, is completely filled/occupied  by the frame of spacetime which is electromagnetic. That is why,  source of light, together with the orbit of earth of 100,000 miles per hour, such light travels at 186,000 miles/sec. forward, sideward, or backward. This is what Michelson-Morley , with the use of interferometer,  found out. Point the interferometer forward and the speed if light is 186,000 miles sec.., point the interferometer at the rear, and the speed of light is same 186000 mile/sec. Thus, the scientific community, including Dr. Einstein,  concluded, light is independent from source. But the  real explanation why the speed of light is constant is because  t the whole outer space is electro-magnetic medium. thus, wherever the source of light is, where ever its direction, it is always on the all encompassing electro-magnetic medium of spacetime. jsa 43.4.19. .

[alancalverd]

Spacetime is not "electromagnetic".

As Maxwell demonstrated, light does not need any medium to propagate.

The quantities μ₀ and ε₀, the "permeability and permittivity of free space" do not refer to the properties of a substance but are the constants required to make our measurement of the speed of light consistent with the rest of our measurement system - meters, seconds and kilograms. By giving them dimensions, we can calculate the properties of electromagnetic radiation in any real medium x in terms of a dimensionless "relative permeability" or "relative permittivity", μ_x ,  ε_x. 

[flummoxed]

. But the  real explanation why the speed of light is constant is because  t the whole outer space is electro-magnetic medium. thus, wherever the source of light is, where ever its direction, it is always on the all encompassing electro-magnetic medium of spacetime. jsa 43.4.19. .

You were doing alright till this part, are you talking about space time being all encompassing and able to transmit electromagnetic forces.

[jsaldea12 (OP)]

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The frame of spacetime  encompasses all  vacuum, outer space, space on earth, and even vacuum of atoms!! Vacuum does not mean it is nothing, it is completely filled/occupied by skein of spacetime. Without electro-magnetic property of spacetime  no transmission from radio station TV station,  and received by receiver radio, TVs. it appears like that. Jsa 3.4.19

[alancalverd]

Utter drivel. If there was any "skein of spacetme" the observed speed of light would vary with the direction of travel of the source or observer.

[Bored chemist]

his is what Michelson-Morley , with the use of interferometer,  found out.

Do you understand the significance of the M M experiment?
They did that experiment on Earth (obviously).
The Earth is spinning on its axis, orbiting a Sun which is, in turn orbiting the centre of the Milky Way. So it is continuously moving.
And yet the experiment detected no motion with respect to what you are calling "spacetime" and they called the Luminiferous  Ether.

Well, if you are on a moving spinning thing, an you don't detect movement WRT the ether, that's either because the ether is following you exactly or it doesn't exist.

Both common sense and other experiments rule out "the ether is following you exactly".
So the only option left is this ether (or spacetime if you want to use the wrong name) doesn't exist.

You are saying their experiment shows that you are right, but in fact it proves that you are wrong- it's just that you didn't understand it.

As I have said before, it would be better if you started by learning some science.

[jsaldea12 (OP)]

Skein is same with frame of spacetime. jsa