What is the "surface gravity" of the universe ?

[killium]

Another thread here got me thinking about that. Once it was asked what was the gravity in the center of the earth and the answer was 0 because all the matter would be pulling on you in every direction, canceling the overall effect.<br /><br />What about the universe ? If we are at the edge of the universe, ALL the universe would be pulling me in one direction so i would feel gravity. I think to find the surface gravity i need to know my distance to the center, maybe this is killer cause there is no center ? <br /><br />Any ideas ? <div class="Discussion_UserSignature"> </div>

 

[siarad]

You can't feel gravity except by going against it. Therefore it should be easier to travel in one direction than another if off-centre.<br />Then again... <br />Copied from <br />I'll never get the hang of this science thingy. So the speed of gravity has been measured & it's in the opposite direction from it's force. Please please how is this? is it clawing it's way through space thus pushing back against any object? like a cars wheel does against the road. If so of what are it's claws made?

 

[igorsboss]

Just as there is no center to the Universe, neither is there an edge. Since there is no edge, there is no surface upon which to create the surface gravitational effect that you envision.<br /><br />Hate to break it to ya, but the question is nonsensical. Sorry.<br />

 

[killium]

If you're not moving and you are in a gravity field that would make you move, you ARE going against gravity thus, you feel it. <div class="Discussion_UserSignature"> </div>

 

[killium]

I agree with you that my question is a bit, well, twisted ! It has no sense if there is no center nor edges but, what if ? <div class="Discussion_UserSignature"> </div>

 

[siarad]

No, it's an very good question & I understand exactly what you're saying but it's against, well sort of, modern science so don't hold your breath for an answer. Modern science says gravity is equal in all directions & you've every right to question that with a well thought out topic.

 

[siarad]

Astronauts have left the Earth & travelled around the Moon & back without feeling gravity, remaining weightless during the journey, despite accelerating on entering Moon orbit & slowing on exit. Only the landers felt gravity. Look up sling-shotting.

 

[heyscottie]

But siriad:<br /><br />Acceleration is indistiguishable from gravity. If I'm in a closed box, there is no experiment I can do to tell if I am accelerating at 9.8 m/s^2 in space far from any gravitational forces or sitting still on the surface of the earth.<br /><br />In any case, I'm not sure what your point is.<br /><br />The original question is indeed an interesting one.<br /><br />IF we (1) assume there is a center and an edge of the universe<br /><br />AND IF we (2) assume that matter is distributed uniformly at any given distance from the center of the universe<br /><br />AND IF we (3) assume we are not at the hypothetical center of the universe<br /><br />AND IF we (4) assume that we have incredibly sensitive equipment that can detect micro acceleration and can subtract local gravity gradients out<br /><br />THEN it is possible we could detect some gravity gradient pointing us toward the center of the universe.<br /><br />Of course, since there is no center or edge, and even if there was, there is no way to build such equipment, this is really a nonsensical answer. Not that that stopped me.

 

[siarad]

<blockquote><font class="small">In reply to:</font><hr /><p>Acceleration is indistiguishable from gravity. If I'm in a closed box, there is no experiment I can do to tell if I am accelerating at 9.8 m/s^2 in space far from any gravitational forces or sitting still on the surface of the earth.<p><hr /></p></p></blockquote><br />My point is, the astronauts were free-falling therefore despite accelerating, decellerating & reversing direction were entirely unaware of it, because they weren't <b>opposing</b> gravity. Therefore the Universe has no surface unless a point of oposition is formed.

 

[igorsboss]

I do not agree that gravity is the same in all directions.<br /><br />Our acceleration due to gravity is calculated using a volume integral, over the entire universe, of the vector acceleration due to gravity for each infinitesimal part of the universe. It just happens that the Earth's proximity dominates this integral for anyone living on Earth's surface.<br /><br />Matter is not distributed uniformly everywhere. For example, there is a direction, called the great attractor, towards which our galaxy is currently accelerating.