I think everyone is right here.
It's just that I think people are misunderstanding the law of conservation of linear momentum. This law is just an observation of what happens, and fortunately makes for easier calculations.
You could say that the rocket is pushing against it's own exhaust, and it just so happens that linear momentum is conserved. Even if it would not be conserved and some of it were 'lost' somehow in the transfer, we could still move around in space, although we would have to throw away more 'shoes' then we do now.
Conservation of linear momentum is directly related to Newton's third law, and IMO it is better to explain it as Dr.A did then through conservation of LM simply because such an explanation can lead down a slippery slope of misunderstanding what that law really is.
(I'm feeling I'm not explaining myself well. Hopefully Dr.A will be able to explain this much more briefly and concisely)
AbE I'll add a precision:
Saying ''linear momentum must be conserved'' is very misleading as an answer because it doesn't have to be conserved. We do observe that it is conserved, but this is because when the two exert a force on each other, it is equal and this entails that linear momentum will be conserved.
SO we move through space because one force provoques another, and because they turn out to be equal, linear momentum happens to be conserved.
Edited by slevesque, : No reason given.
Edited by slevesque, : No reason given.
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