In the older days, people probably didn't realize that air exists. There still are people who think that air is like nothing, being some kind of gas that weighs nothing, has no pressure, and such. Yes; wind, wind is something. That's like fish who don't realize that there is water all around them. "Water? Where?".


One cube of space
Start with a cube of 1x1x1 meter, full of water.
Then take out all the water. Is the cube empty now?
No. Now there is air in it. It got in there while the water went out.
Now take out all the air.
While doing so, one will discover that the atmosphere we live in, is pressurized. The pressure is more than 1kg of force on each cm2, that's more than 10000kg on each of the 6 sides!
But we struggle and overcome, to in the end have a cube free of air.
Is the cube empty now?
It is a 'vacuum', a space without atoms.
Yes, but is the cube empty now?
Sound waves can't travel through this vacuum, because sound needs an atomic medium to travel through, such as: pressurized air, or a solid object.
But radio waves can still travel through this vacuum, so it seems logic that there still is some kind of non-atommic medium present. The force of gravity, whatever that may be, is also present in this vacuum.

The area of 1 cubic meter is still here. If we had removed everything, the area would be gone. Conclusion: a room doesn't disappear when all atoms are removed from it. Space doesn't start outside the Earth; it is everywhere. Atoms and such are probably structures that are made out of this space material and energy (energy... what is that?!).
Could vacuum space be kind of similar to air: a pressurized fluid?
Or is the fabric of space a structure that can be bent, but does not flow, similar to say gelatin pudding?


Atoms, Acceleration and Gravity, in space.
Imagine 1 tomato in a completely empty space. No stars, no dust, no light, nothing else other than that tomato. What is its speed? There is no way to tell, because speed is always relative to something else, but there is nothing else and it seems impossible to have a speed relative to space.
Now imagine a second tomato. It is not so far away, and the distance between them is changing. Both now have a speed, relative to the other. But who is moving?
A) tomato #1 is moving.
B) tomato #2 is moving.
C) both tomatos are moving.
D) non of them are moving.
How could D be true? It makes no sense.
Well; the only thing that seems clear is that the distance in between the two tomatos is changing, so maybe its only the space in between that is moving.

When you're inside a closed box, there is no way to tell if you are moving at a constant speed or not moving at all. You can't feel it, nor measure it with instruments.
What you can feel and measure is: acceleration. When you're inside that box and feel the force of acceleration; things have weight. Your instruments tell you there is an acceleration of 1G. What could be the case?
A) The box is standing on the surface of the Earth.
B) The box is in space and accelerating towards Mars.
C) The box is in space and de-accelerating near Mars.
All three could be true. There is no way to distinguish which is the case. One thing is sure: there is no difference between accelerating and de-accelerating. That's just the same thing in the opposite direction. But there may also be no difference between acceleration and gravity.
One more box example: you don't experience any acceleration? Don't conclude there is nothing going on. You may be orbiting around a planet, or falling down to it faster and faster.

It's weird how stuff (atom based bodies) travels through vacuum space, especially relative to what we are used to on the surface of the Earth; air-resistance and 1G gravity. Stuff resists against acceleration. "Inertia" What is that exactly? Stuff traveling though vacuum space at a constant speed is not slow down by 'space-resistance'. If there would be space-resistance, everything would accelerate down to a speed of zero, relative to the fabric of space and everything in it. But that is clearly not the case.


Light in Space.
The speed of sound in standard air is about 343 meters per second. That is pretty fast, but you know from experience that sound comming from far away takes longer to reach you than light. Lightning and thunder for example.
The speed of light in a vacuum goes a little bit faster: 299,792,458 meters per second!

But wait a second... The speed of sound is relative to the medium it is traveling through. To what do we measure the speed of light? Relative to the fabric of space seems impossible. Are we talking about relative to the position where the photon was created? How do we know what an absolute position and what an absolute distance of 299,792,458 meters is? And how do we know how long one second takes? Are distance and time absolute constants?

It seems that nothing can propagate faster than a photon. How does a photon move though? What structure does it have? It has a wave length, so I guess it either vibrates or rotates. If there is motion inside a photon, and its average speed is the speed of light, then parts of it go slower than light, and the other parts go faster than light, especially if the internal alternating motion is in the direction of travel.

One photon travels straight through space. Not like a wave on water or a sound wave in air. Though when light passes through a part of space were there's a lot of gravity, it's path can curve a bit. Gravity slows down light, that has been proven.

I can't go faster than light? Really? But I don't know what my speed is. Relative to what? If I had a rocket with an unlimited propulsion system and accelerate in one direction for 1000 years, and then stop the thrust, what is my speed then? I don't know now and I won't know then. My speed relative to what? Speed is relative, and can't be relative to space. If there is no 'eather', there can't be a speed limit. Right?

Space wind.
The Earth is spinning and traveling around our sun. One would except some kind of wind from the fabric of space, if the fabric of space is like a pressurized fluid or agelatin pudding.

What is true, from the illustration above:
A) Light coming from an incandescent lamp travels with equal speed in all directions, no matter what the speed of the lamp is, relative to other objects.
B) If the speed of the incandescent lamp relative to the fabric of space is not zero, light in different directions will travel with different speeds relative to the lamp, because light can only travel through space with the speed of light.
C) Both theorem are not entirely true.

If A is true, then... things would become weird. If the speed of light is always the same, relative to it's source, then the light from somebody walking away from me, is traveling away from me faster than the speed of light, and to me slower than the speed of light. This feels wrong.
If B is true, then light in space is not that different from sound in air, and measuring your speed relative to the fabric of space is possible. This feels right.
If C is true, then what?

The Michelson–Morley experiment was performed in 1887 by Albert Michelson and Edward Morley. It attempted to detect the relative motion of matter through the stationary luminiferous aether ("aether wind"). The negative results are generally considered to be the first strong evidence against the aether theory, and initiated a line of research that eventually led to special relativity, in which the stationary aether concept has no role.
Michelson–Morley type experiments have been repeated many times with steadily increasing sensitivity. These include experiments from 1902 to 1905, and a series of experiments in the 1920s. In addition, recent resonator experiments have confirmed the absence of any aether wind at the 10−17 level. Together with the Ives–Stilwell and Kennedy–Thorndike experiments, it forms one of the fundamental tests of special relativity theory. Read more about this on Wikipedia

So, however strange, theorem A appears to be true:
Light coming from an incandescent lamp travels with equal speed in all directions, relative to the lamp, no matter what the speed of the lamp is, relative to other objects. To make matters even stranger; the light from somebody walking away from me, is traveling away from me with the speed of light, and to also with the speed of light.

How can this be? Is our perception of distance and time wrong?




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To the observer it's like...
I must say that I don't really understand the theory of special relativity yet, but there is one element of it that may cause unnecessary confusion: "to the observer it is like...". A rather look at it from the perspective of a special observer, an 'entangled observer' that can see without a delay in information.
An other part that bugs me is: "as your speed increases, so does your mass". But there is no such thing as absolute speed, things don't have absolute speed. so it makes no sense to me yet. I should probably read some more about it.

Or does it only matter where the light starts to travel, no matter how fast the light source goes? As a photon is created, that position is its starting-point from where it will travel away with the speed of light.

As there is no way to tell what your speed is relative to the fabric of space, then how do you know what your absolute speed is? You don't. Speed is a measure of how fast the distance between two objects is changing. It is possible to feel and measure the forces of acceleration, but if your speed is constant, there is no way to tell what your speed is. And the forces of gravity... feel and measure exactly the same as acceleration. Are they the same?

What about two light sources that shine towards each other?
The speed of these beam's photons, is 2 times the speed of light, relative to the other beam's photons. Yes, but relative to their starting positions, they traveled with just 1 time speed of light.
If this is correct, doesn't that proof that the fabric of space is some kind of medium?


Vortex ring structures.
I think that energy, when applied in a certain way to space, will form atoms and such that we recognize as 'something', similar to how vortex rings in air can form under the right circumstances.
Energy I think has the ability to make a change in the condition of space, and a local change in space can cause energy its path to curve.

In air, it is impressive to see how long a vortex ring can stay intact, how far and fast this structure of air and energy can travel. This in a pressurized atmosphere of gasses that gives air-resistance. Energy traveling through the fabric of space may go on for ever, if there is no space-resistance.


Traveling faster than light.
If the fabric of space is not fixed, and it is possible to move one part of space relative to an other part of space, the it may be possible to travel way faster than light, without actually going faster than light. Then the question becomes; how fast can a part of space travel through space? And if there is a limit to that, one could make: a space within a space within a space within a space. If all these spaces would move in the same direction, and you'd be in the most inner space... Warp speed!
How much energy would that cost? If space indeed has no inertia, it will not resist against acceleration. But the creation of a large... warp field, will probably not come for free. Reminds me of creating an electromagnetic field, which costs power to create, but which also releases energy when returning to the normal state. Recycling warp field energy... not yet a topic of debate.



The speed of energy and time.
The speed of energy in vacuum space will probably be equal to the speed of light.
If there is an equal speed limit for light in all directions, that medium is apparently holding the same position.
The speed of time I think is equal to the speed of energy. And as the condition of space is altered, the speed of energy and thus the speed of time shall change. The speed of time can go faster or slower, relative to an other part of space, but the direction of time can probably not be reversed.
It has been proven that: the more gravity force is present in a part of space, the slower time goes there.


Gravity in space.
If the structure of space has some kind of pressure, that could explain why the universe is expanding. And if a great lot of atoms can together reduce the pressure of the surrounding space, then it may just be so that gravity is not atoms pulling of atoms, but instead: space pushing atoms together.

The limits of our imagination.
Most of what we experience in our personal virtual reality (in our brains), is just a tiny reflection of the truth. The ideas we have about: vacuum space, gravity, time, distance and such, may still be far from the optimal reflection.



Distance


Inertia


Entanglement



Wow; my head is spinning. I still don't know what space is.

Giesbert