
Originally Posted by
smalcat
I am a bit reluctant to post, as I have not read the complete thread.
Of relativity, clocks and problems:
So it all started with Galileo, he first thought of relativity. It kind of goes like this: I am on a ship that relative towards the shore travel at certain speed lets say 5knots in one direction, and there is another ship that goes in the opposite direction also with the speed 5 knots. Both ships are on the same line (ie they will crash).
Galileo claimed, that if you are standing on the first ship, you can consider yourself standing still and the other ship crashing into you with the speed of 10 knots. Interestingly someone on the second ship can claim he is standing still and it is you who crashed into them with 10knots. Both are considered right in their claims, the observation systems are different.
Most people today accept this relativity and even take it for granted and even trivial.
There is one problem though. No matter how fast we move compared to a source of light, the speed of the light is the same. This we measure. There was no good theory that would explain that until the (special) theory of relativity.
So its not that we have observed some clocks to be slower than others, its that we have observed that light has the same speed, even if we are traveling with aprox 0.1% of the speed of light (30km/s) towards the source of the light. I would be extremely interested if anyone would try to explain why that is without using theory of relativity.
Some other random thoughts:
- each object (ie earth) has geostationary orbit, it is dependent on the objects mass and rotation, but until the mass of the satellite is comparably small not on the mass of its satellite
- if moon (moon is not in geostationary orbit) was switched with an apple there would be a change. Moon-Earth system circles around barycenter some 5000km from the center of Earth (= 1000km bellow surface), Apple-Earth system would circle almost at the exact centre of the earth. This difference of 5000km is rather small compared to the earth moon distance.