Ex-chem is the kind of cheerleader who pretends to instruct me by saying:
I invite you to consider the motion of the moon round the Earth, and the planets round the sun, and the sun round the Milky Way galaxy. Who is to say that any of these is at rest, while the others are in motion around it?...There are no grounds for preferring any of these to the others.
So I respond to his suggestion by posting this:
Posted 15 April 2018 - 01:53 PM
Some people mistake Galileo's "parable of the ship" as a argument that relative motion cannot be detected, but that's hardly the case. He noted that in a windowless cabin below deck you would not be able to sensibly detect lack of motion from uniform motion, sure. But he was also quick to point out that once the sailor went up on deck, felt the wind blowing, saw the sails billowed, and saw points on the shoreline in motion relative to him, he would know he was moving.
Galileo is celebrated for muttering "and yet it [the earth] moves," on his way out of the inquisition chamber after being forced to renounce copernican theory. He knew motion when he saw (i.e., could credibly deduce) it. If you're on a train and want to know if you've left the station while you were sleeping, just look out the window. Nothing complicated about that, eh?
When I hit a ball with a baseball bat, I have plenty of "evidence," both sensory and logical, which tells me I don't suddenly start moving away from the ball while it remains motionless.
Once again, I would assert that anyone who actually believes otherwise is mentally unbalanced.
What does he have to say then? Absolutely nothing, whether good, bad, or indifferent.
Another cheerleader, who called me a "crank," had already asked me:
While on that train, if it's moving smoothly at some constant speed, what experiment could you do to conclude you were "really" moving and someone standing on the ground was "really" not moving?
He too offered no further response.
Galileo's relativity principle would seem to imply that there is no way to determine an absolute speed for a given object. But speed is not motion.
The proposition that if you can't know an absolute speed, then you can't know which of two objects is moving relative to the other is obviously completely illogical and unfounded, yet it seems to be widely believed amongst relativists. That's what they've been taught to say, so they give it no further thought, apparently. They just repeat it, like a parrot. Even in SR, non-inertial motion is deemed to be absolute (which means that you can tell the accelerated object is moving). You can easily say that even without EVER knowing any absolute speed.
Before SR, and to this day, scientists assert, with innumerable good reasons, that, relatively speaking, the earth revolves around the "sun" (solar barycenter) NOT vice versa and not that "we can't know." After the Michelson-Morley experiment, nobody, and I do mean NOBODY who was rational, said: "Well, OK, then. This experiment proves that the earth is absolutely motionless after all. We have hitherto been mistaken." Granted, flat-earthers and relativists might still try to make that claim, but.....
Relativists then actually try to amplify this fallacious reasoning. They may start by saying that "we can't know" if the earth orbits the moon or vice versa. But in order for their theory to "correspond to reality" they need to go beyond that. So "we can't know" which one is correct, then gets turned into the ridiculous proposition that "both views are correct."
Ex-chem doesn't give a single thought to that before asserting that the simple heliocentric "fact" is "unknowable." He's a cheerleader; he aint no playa.
Edited by Moronium, 13 June 2018 - 01:47 PM.