Physics special relativity?
The 2 postulates
1. The laws of physics are the same for all observers in uniform motion relative to one another (Galileo's principle of relativity),
2. The speed of light in a vacuum is the same for all observers, regardless of their relative motion or of the motion of the source of the light.
Can you explain what eeach of these mean in simpler terms for example what is the observer ? what does relative to mean?
what does in uniform motion mean? what does relative motion mean?
and please explain what each of the principles mean, i think i know what the second one means but i need someone to tell me in much simpler terms to be for sure thanks
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Postulate 1
Uniform motion = means that the motion is the same
Relative to each other = it is the same to all of us who are in the same room
So it means that if we're all in the same room, or in the same environment, then if we see a ball falling, we will all see it fall at the same speed.
Postulate 2
This means that the speed of light is constant.
For example, a car speed is not constant, because if you were driving your car at me at 30 mph, it is going 30 mph. But if i was also driving at 30 mph towards you, then when we pass each other, it would seem to me that you were moving 60 mph, but to someone standing on the street, we both are just moving 30 mph.
But the speed of light is different. Even if i was moving at speed of light at you, and you were moving at speed of light toward me, you and i, and the person on the street would see it at the speed of light and not double the speed of light.
If you on the platform at a station and I am on a train moving at constant speed then we are observers moving relative to each other with uniform speed.
The laws of physics will be/have to be the same in each of our frames of reference. Sometimes when you are on a train and there is one next to you it is not obvious, if you have just woken up, which of you is moving. Is it your train or the one next to you. You need to refer to another object in a different frame of reference. It is impossible to perform an experiment which will tell you if you are at "rest" or in a state of uniform motion.
One of the premises of the STR is that it is necessary for c to be constant in all frames of reference. A bullet fired from a moving gun has the velocity of the bullet added to the velocity of the gun relative to the ground. This is not true in STR. A spaceship with a torch at one end means that the light still travels at c relative to a "fixed" frame of reference.