difference between free fall and zero gravity?

[Thabiguy]

It's a very non-traditional way of teaching and understanding the subject, and I don't see that it makes it any easier. It certainly doesn't make it easier from the point of view of understanding how Einstein came up with it, and IMO it doesn't make it clear what the difference is between classical mechanics and spacetime mechanics; this is an important distinction today because quantum mechanics uses SR, not GR.

I understand. It's a pity then that I have, possibly by chance, encountered that way frequently enough that it formed my way of understanding it. Now I've seen another perspective.

I keep saying the same thing, and you keep saying the same thing. Try again, but this time try to put it in terms everyone else will understand. In my opinion, while we've basically been patting ourselves on the backs about how smart we are, everyone else is getting very little from it. That's not what I'm interested in here.

That was not my intention. I have asked you for clarification on the points that I did not understand, and you have provided it. I now understand better what you had said, and the points that you now make seem valid. I don't see the need to repeat what I said; I believe it was valid from a viewpoint that may be irrelevant from the perspective of what you say now. And I really have nothing new to add or disagree about regarding your latest post.

All that remains is to thank you; you did expand my horizons, and I appreciate that you took your time to do that.

 

[Schneibster]

Well, you said acceleration need not be constant to be acceleration, and then cited rotational motion as an example. And I was going on the (wrong) idea that rotational motion is constant acceleration. I forgot about the fact that acceleration is a vector. Mea culpa.

Ah. Remember also that the frame of the person standing on the outer rim of the space station is also a valid frame, and is also an accelerated frame, and is further more a frame that is, from the point of view of an inertial observer outside a gravity field, both rotating and revolving. And consider what that observer sees, and that it is indistinguishable from gravity (the odd Coriolis effect aside).

Your mistake is a natural one. No stress.

 

[Schneibster]

All that remains is to thank you; you did expand my horizons, and I appreciate that you took your time to do that.

I was getting frustrated; but I'll tell you, I don't hear that every day, and that makes it worth it, and would have made more frustration worth it. Glad I gave you something to ponder.

 

[Schneibster]

Where did you learn this stuff?

I read a lot, and I already had an EE, so the math, while somewhat daunting, isn't beyond me, although I can't claim by any means to be a real physicist.