So how do you propose we locate these points in space?
The Swing of a Pendulum
- Thread starter Motor Daddy
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So how do you propose we locate these points in space?
Motor Daddy
Valued Senior Member
That tells me nothing on how to locate a point in space. According to that drawing I can say I am at point 0,0,0 and if I drive 10 miles I will be at the absolute point of 10,0,0. If it takes an hour to get there then I had an absolute average speed of 10 mph. Which I dare say even you would agree is absurd.
So how do you find these 2 starting and stopping points in space?
No, not much. Go back to your initial scenario. You introduced a second car for no apparent reason, other that to create the illusion that the relative position of one car from the other has something to do with the meaning of absolute velocity. It doesn't. I am showing you how to disabuse yourself of that error.
Again: there is no absolute position in space. The difference in position from the two cars is a relative measurement. Even if the cars moved at exactly the same rate (impossible to achieve without welding them together, even then there is some wiggle in the joint) the relative velocity is simply zero.
The motion of the pendulum is dependent on two external forces: gravity, and the force of the tires against the pavement. These two forces add. The composite force is converted through the pendulum's frame and resolves into the harmonic motion of the bob. We can model the pendulum and solve for this (see the simulation I gave you for an example).
However, those forces are relative. The force of gravity is relative to the center of the earth (c.m.) and force due to traction is relative to the pavement at a particular moment in time.
From this and what I provided earlier, you now have a basis for understanding that there is no absolute motion in your scenario in the OP.
Motor Daddy
Valued Senior Member
Those are light seconds. The cube's walls are 1 light second in length, and the source remains at the center .5 light seconds from each receiver at all times as the cube travels in the absolute frame away from the center of the light sphere (which remains motionless in the absolute frame.)
I think I see what you are trying to say. Are you saying, that anytime a light sphere is emitted from a point, that point by definition and in actual fact is a fixed point in absolute space?
Motor Daddy
Valued Senior Member
Look at frame 2. The time is t=.65 seconds and the radius of the light sphere is according to the speed of light. But if you are the z receiver .5 light seconds away from the source in the cube frame, then you have problems, as it took .65 seconds for light to travel from the source at t=0 to the z receiver, which is only .5 light seconds in the cube frame. Uh OH!
Motor Daddy
Valued Senior Member
Exactly.
...and light travels away from that point in all directions at the same speed, so light is defining distance in the absolute frame as it travels away from that point..
Motor Daddy
Valued Senior Member
Objects also travel in the absolute frame at the same time,,and while the driver of that object may have had a few too many, light travel never lies!
Well good for me. I never got that this is what you were saying because it is really quite off base. I can see how you would come to believe that and hold on to it, I suppose. Unfortunately that belief is demonstrably false. Experiments (all of them) show that to be completely wrong. So I guess you are just going to believe what you want, the facts be damned.
Have a good one, it's getting to late for me...
Have a good one, it's getting to late for me...
I don't think I ever said there was .. or there wasn't. Indeed, it is difficult to see how there would be. Jame R said, however,
there are plenty of absolutes in spacetime - just not the ones you think there are
so it would be interesting to see what he means.
I meant simply this; eminent scientists spoke of spacetime as a reality for decades, then eminent scientists spoke of 'the myth of spacetime' and 'spacetime is a fairytale', etc. I have no great problem with this I was merely pointing it out because it kinda confirms my suspicion that all knowledge is provisional. And if you wanted to disccuss this issue further, the thread in physics and maths (or wherever it is) might be the place.
Weeds .. Ah, those despotic weeds ..
http://www.poemhunter.com/poem/the-despot/
No, but I am still suspended about absolute position ..
Still waiting with much interest to hear more about this, James R.