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If you are in an accelerating reference frame, then Newton’s laws still apply because the sum of all forces still equals mass X acceleration, you just have extra forces (such as the coriolis and centrifugal forces in the earths rotationally accelerating frame).

No, your mass approaches infinity as your velocity approaches the speed of light. In Newtons equations your mass stays constant as you accelerate, Newton is incorrect. Even at non relativistic speeds your mass increases as you accelerate, we just may not be able to measure it : )

But that wasn't precisely what you were stating was it? I think you were putting someone in a box (no other references) and stating for that observer Newton physics would work fine. I already agreed that would be correct. It only gets interesting when you get other objects in your frame of reference : )

Newton’s laws and Einstein’s predictions do not give the same result when gravitational fields are much larger than those on earth. Einstein’s theory of General Relativity is the most accurate gravitational theory we have because it works in all reference frames.

Correct. Newton was almost right and since his equations are a lot easier we use them.

The steady state example actually illustrates Einstein’s idea in SR that the laws of physics are the same in all non-accelerating reference frames. It so happens that Newtonian mechanics is usually sufficient in these reference frames.

What you really mean to say is at non relativistic speeds and/or large Gravity fields. You do know that you are being accelerated right now, don't you?

Are you even able to make a response without purposely insulting someone with your condescension?

If you are in an accelerating reference frame, then Newton’s laws still apply because the sum of all forces still equals mass X acceleration, you just have extra forces (such as the coriolis and centrifugal forces in the earths rotationally accelerating frame). No, your mass approaches infinity as your velocity approaches the speed of light. In Newtons equations your mass stays constant as you accelerate, Newton is incorrect. Even at non relativistic speeds your mass increases as you accelerate, we just may not be able to measure it : )

Ok well I wasn't including relativity in this, but yes if you are measuring objects moving relativistically then you will of course have the strange increases in mass, etc My intent in the explanation was to show that Newton's laws hold INSIDE, lets say, an airplane which is accelerating (not relativistically). The motion of objects in this frame abides by Newton's laws, but with additional fictitious forces.

The steady state example actually illustrates Einstein’s idea in SR that the laws of physics are the same in all non-accelerating reference frames. It so happens that Newtonian mechanics is usually sufficient in these reference frames. What you really mean to say is at non relativistic speeds and/or large Gravity fields. You do know that you are being accelerated right now, don't you?

I think we are looking at this from two different angles. The postulate of special relativity says that there is no experiment you can perform to indicate that you are moving if you are inside a constant velocity reference frame.

The earth is rotationally accelerating, which I mentioned earlier (centripitally accelerating as well). Newton's laws still apply on earth, you just have to include the fictitious forces and apply Newton's laws.