Posted: Jul 28, 2014 3:18 pm
Evolving wrote:Just to address any misconception that may have arisen from mentioning orbits (and to give me a chance to pontificate on physics again...):
Free fall is, as Shrunk pointed out, a technical term meaning that gravity is the only force affecting you (all other forces are of negligible strength). Any object in space that is not being impelled by some thrusting thing like a rocket or an ion drive is in free fall in this sense; it doesn't matter which trajectory it is on.
If you are in a spacecraft that is in free fall, and you take that spacecraft as your frame of reference, then there is no preferred direction within that frame, as there is while standing on the ground: you can float equally readily in any direction you like within that frame of reference and it will seem to you as if you have no weight.
A spacecraft on the way to the Moon is in free fall, and so are the people inside it. Consequently, those people will experience what seems to be weightlessness.
It was my conjecture (and Comfort seems to bear this out in his second post, in which he reports on the corrections he has received) that it was seeing footage like this that misled him into thinking that there is no gravity in space.
This is likely correct - and the exact reason NASA no longer refers to something being "weightless" or in "zero gravity" but instead uses the term "microgravity" - because there is still a small gravitational attraction between the astronaut and the spacecraft.
Of course, knowing this would require Comfort to keep up with modern scientific understanding and terminology - and his understanding of science has apparently congealed at a level circa 2,500 years ago.