Hi, I hope to make this accessible to as many people as possible.
Special Relativity tries to make the argument that a moving observer will measure light to travel at the same speed as a stationary one, and indeed that all reference frames are equal.
This replaced the concept of a reference frame provided by a fixed or entrained medium of space , an ‘aether’, there is evidence against the fixed type but none against the entrained variety.
The speed of light is measured at 299,792,458 meters a second on earth in a vacuum from the earth frame of reference.
If a pulse of light travels along a train track past a train moving in the same direction, we would expect the motion of the train to slow the speed light seem to be moving as measured by the train.
Special Relativity argues that there are 2 effects that take place to ensure the speed of light it still measured the same by the train passengers.
First is length contraction, this is where the train gets slightly shorter the faster it moves, and because there are no preferred frames of motion the world seems to shrink from the train passengers reference frame.
If the speed of light is measured by 2 sensors 1 meter apart with a clock to detect how long between the first and second sensor take to be triggered, then motion in the direction of the light will make the delay longer (light will seem slower) but the contraction of length as seen by earth reference will shrink the 1 meter separation to a smaller distance, this will compensate so the time it takes matches the Earths measure for the speed of light.
And there is a second way that Special Relativity tries to explain this, with time dilation.
That is the rate of time on the train slows the faster it moves, as such even if the light has further to travel when the train is moving with the light, it will measure the speed the same since all clocks on the train will run more slowly which would cause the the delay to be measured as less on the train than off.
Both of these effects would work together to increase the measured speed of light so it measures the same as a stationary viewer despite being seemingly slowed by the motion of the train.
Amazingly this whole thing falls apart if which we are measuring light moving with the train, we also try to measure light moving in the opposite direction.
Now the speed of light should be found to be higher because of the motion of the train adding to the velocity between the light and the train.
But here the length contraction makes it worse, the meter separation of the sensors shrinks causing the speeding light to be measured to be even faster, and as the clocks on the train are observed to slow, even less time passes between the light hitting the 2 sensors.
All these tricky that relativity only works in one direction, in the other direction it makes the difference even worse than it would be.
This proves that the speed if light can not be the same for all reference frames.
Special Relativity simply fails.
But there is more.
Time dilation can’t exist either.
Special Relativity holds that all frames of reference are equal, so time might to be moving very slowly when we look at a spaceship moving near the speed of light, but on that spaceship they would see us as moving very slowly.
This is always given from the point of view of a spaceship leaving earth.
But this fails to take into account the Doppler effect, this is the that changes the sound of a car horn or engine when it moves towards you .vs when it moves away.
If I was shooting an automatic gun at you in a car that was approaching you, you would find the bullets coming at a swifter rate than if I were stopped, and a slower rate if I were driving away.
That is because when I am getting nearer each bullet has less distance to get to you. And if I am driving away each bullet has a greater distance, which makes it seem that time has slowed down in my car.
Of course this is just an illusion, this type of illusive time dilation can be removed by calculation, or merely placing an observer to the side (communication orthogonal to motion) :
OB1 OB2-> OB3
While OB1 sees OB2 time rate as slower since OB1 is moving away and OB2 sees OB1’s time rate as being slower for the same reason, OB3 can see the time rate of OB-1 and OB2 without this distortion from Doppler time distortion.
The 3 observers can sync their clocks and it is easy for OB3 and OB2 to see which is experiencing the fastest and slowest time.
They can’t disagree like OB1 and OB2 because they are very close to each other, and could in an instant enter the same reference frame, if both saw the other as having time move more slowly then both sees the clock on the other as being behind their own even when in a moment they can enter the same frame they must agree on reality then.
Could seconds, minutes or years worth of frozen time suddenly unfold in an instant so their clocks match? This would be totally insane and unsupported.
Clearly OB2 and OB3 could agree on which experiences the fastest time rate, this would allow for a discovery of a preffered frame of reference where time moves fastest, but this is not allowed by Special Relativity.
That would be an aether (ether) model.
Indeed if OB2 was orbiting OB3 at near the speed of light, they would be precisely the same distance apart forever, Special Relativity would argue that each should see time on the other almost stop entirely, centuries could pass from the perspective of one observer while only seconds would have passed for the other, and both observers would consider that that they had experienced centuries while the other had not moved.
Clearly none of this could possibly happen, twin paradox indeed.
The world we like in sadly has more respect for the status quo than it has a love for the truth. Intellectual dishonesty and zealot are the name of the game.