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englebart wrote: “hair challenged”*
Harrumph  . I prefer the term "follicley-disadvantaged", thank you very much [sniff].
Software Zen: delete this;
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We need a "throwing up" emoji response...
Seriously, if my family were anything like that, I would have walked out years ago!
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.
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Greetings I learned some time ago from a source I now do not recall the astronauts aboard the Space Station do not experience micro-gravity or zero g in the expected sense In fact it was explained the force of Earth's gravity at that altitude is in fact just under .9 of the surface They are merely falling along w/ the station So it is no different than the "Vomit Comet" It would be nice if the popular press would explain it so Kind Regards - Cheerio
My sympathies to the SPAM moderator
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PaltryProgrammer wrote: It would be nice if the popular press would explain it so
You think the "journalists" working for the popular press are in a position to explain anything? That's cute.
I can't find the obligatory XKCD comic on that very topic...
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Relatively, the 'experienced' gravity is 'zero' - so your point is kinda silly. Yes, they are in Earth's gravity well, but 'zero gravity' is a good description of the perceived effect.
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I think “free fall” is the better term.
You need to make it to the lunar LaGrange points for a closer approximation of zero G. (You are still probably free falling around the earth, the moon, and the sun all at the same time, though. Orbits are tricky.)
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No you don't.
Any object in a ballistic trajectory. - a shell, a missile after it finishes its acceleration phase, a satellite (artificial or natural) is in "zero gravity" (neglecting atmospheric effects for the shell).
Having mass, they of course generate their own "gravitational" field, but that's another, much hairier story. In fact even the generalised TWO-body problem does not have an analytical solution in General Relativity; all solutions are calculated using numerical approaches.
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.
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“Side fall” then?
If they weren’t moving that fast, they would start falling. The kind of “free fall” that ends in a splat. (Or for earth, burn up in the atmosphere)
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You are asking the wrong question. From the POV of General Relativity, the question isn't "why things fall", but "what makes them stop when they hit the ground?"
A less facetious answer would be that an massive object "warps space-time" around it. The objects in orbit are moving along a path (I.e. both position and velocity) in that "warped space-time" that avoids intersection with the massive object.
(If you want a more quantative answer, study Physics to reach the level of confusion enjoyed by most physicists...  )
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.
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space station travels roughly 17,150 miles per hour. Orbiting earth once every 92 minutes. The astronauts float in "air" at that speed.
people in this thread can debate the gravity sh*t all they want, I think what I just posted is freaking cool AF.
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Yes, if the earth rotated at that speed people on the equator would be able to float above the ground.
“That which can be asserted without evidence, can be dismissed without evidence.”
― Christopher Hitchens
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How would "real" zero gravity be different from what the Space Station guys experience?
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Greetings According to Newton's law - Cheerio
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It isn't.
According to General Relativity's Principle of Equivalence, a local acceleration may be treated as a "gravitational" field, and vice versa.
No acceleration == no "gravitational" field.
(For those that claim that they are not being accelerated while sitting in a chair here on Earth, that is because powerful non-"gravitational" forces are acting in the opposite direction. In General Relavivity, it is not "why things fall" that requires explaining, but why they stop when they hit the ground...)
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.
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The old “elevator” thought experiment.
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Exactly.
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.
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You've said this twice
In General Relavivity, it is not "why things fall" that requires explaining, but why they stop when they hit the ground
I agree with you that "gravitation" is just one of many forces and the balancing of forces is what makes the magic of "zero gravity" (no effective forces in a singular direction), but isn't that because F = ma and not because E = mcc?
We stop when we hit the ground because the ground has reciprocating force (known as Normal force) against that which strikes - it has momentum which is conserved. Relativity comes into play in the conversion of kinetic energy into heat at the impact, but is it a factor in the fall?
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Were spacetime around mass-bearing objects not warped, all movement would be at constant velocity (speed + direction). It is only the warping of spacetime around mass-bearing objects that causes movement to appear accelerated to us.
Note that any object moving freely in warped spacetime does not feel any acceleration effects. This is true whether we perceive it as "falling" (and about to splatter on the ground), whether we perceive it as "in orbit", or whether we perceive it as moving at above "escape velocity".
What happens when an object hits the ground is that non-gravitational forces (electrostatic repulsion between atoms) start acting. It is then that the object will perceive acceleration, and part of its energy may be turned into other forms (usually heat).
Freedom is the freedom to say that two plus two make four. If that is granted, all else follows.
-- 6079 Smith W.
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> What happens when an object hits the ground is that non-gravitational forces (electrostatic repulsion between atoms) start acting. It is then that the object will perceive acceleration
Yes.
And since all mechanical and chemical interactions are ultimately due to the Electromagnetic Interaction, that's the only interaction the body can sense. The presence or absence of a Gravitational Field is irrelevant to the sensation of weight. "Weightiness" is entirely due to an unbalanced electrostatic repulsion.
(An equal-and-opposite vice-like compression doesn't provide any sense of self-weight or any up-down reference; it doesn't orient the vestibular system.)
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Depending on your frame of reference...? 
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According to Hitch Hikers Guide to the Galaxy: There is an art to flying, or rather a knack. The knack lies in learning how to throw yourself at the ground and miss. ... Clearly, it is this second part, the missing, that presents the difficulties.”
—The Guide[src]
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