Posted on Jun 26, 2015
CH (MAJ) William Beaver
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My kid asked me how far could I go and still be going up? I need to sharpen my physics skills. What is the answer to his question? Which way is up in outer space? Is there no 'up' and 'down?' Or is there just 'here'and 'there?' Or is it really 'now' and 'then?'
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Responses: 26
CPT Zachary Brooks
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Ender says: The enemy gate is down
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PVT Robert Gresham
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This is probably not the best scientific answer,  but, very simply, where there is no gravity, there is no up.

If you remember the old Star Trek series, and just about any other "outer-space" based sci-fi, you have to have a universal coordinate system that takes into account extra vectors, as opposed to a map or planetary globe which, for the most part only takes into account North-South and East-West.  In the case of an open area of space you would have to add at least a 3rd set of vectors which would represent, for lack of a better term, up-down.

It's very confusing, as soon as you leave the boundaries of a planet with gravity, but you can compare it to floating in blackness. If you don't know where you are, and have no way to map your progress, there is for all intents, no direction.

Basically, "Up", ends as soon as gravity ceases to be a factor. However, to map an area, a vector to cover the area "up-down" must be used. (Brains fully fried, now??)          
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SPC George Rudenko
SPC George Rudenko
9 y
Gravity exists everywherre.
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PVT Robert Gresham
PVT Robert Gresham
7 y
SPC George Rudenko, okay, true enough. I was trying to give a simplified answer to a very complicated question. Can you give a better one ?? I noticed you didn't leave ANY answer, just a little jab at mine. It's easy to pick apart an answer like this one, especially when the person answering didn't choose astrophysics as a major......BTW..."everywhere" only has one "r". Have a great day !!
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SSG Environmental Specialist
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7 y
SPC George Rudenko - No gravity on exist in matter, the larger the matter i.e. say a planet the more the pull of gravity. Most of space is void of matter. The sun in our solar system has a gravitational pull that reaches out for billions of miles but again a the pull on a person would be very insignificant.
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PVT Robert Gresham
PVT Robert Gresham
7 y
@SSG James Phillips, thank you for that explanation. As I said, I'm no expert on the subject, but I tried to add my ideas on the subject. As I said in the original post, I know it's it's not the best scientific answer. Your comment also helps me to understand the question a bit better. I appreciate it.
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1SG Vet Technician
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Classically, "Up" is away from the action of gravity, or in other words, the opposite direction of the pull the gravitational body. In our case, the opposite direction of the ground, the Earth. Taking that to the extreme, "Up" in space would be in a direction from the central core of our Solar System, the Milky Way. But this is such a great distance, that effectively from a single person's perspective in space, you could point in basically any direction and have "up".

One of the ways our body perceives "up" is by the gravitational pull on sensors in our inner ear. That is why we can feel "upside down" if we are head towards the ground, as anyone who has been in a rollover trainer well knows. In space, we lose this gravitational sense in our middle ear and lose the ability to determine "up". So in that sense, there is no "up" in space. Because of this, Astronauts will often refer to something relative to their position. "the red button above your head" will tell the astronaut to look "above" his head, regardless of his orientation in the spacecraft.

if there is artificial gravitational forces, such as created by spinning a space station, then the concept of up and down will return, but relative to the spin axis of the space station.
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