If you are in space and time, how can you define an upper limit or a lower limit in the aquarium? You cannot, as goes and begs the answer. Without a magnetic pole, there is no north or south directionality.

If this be the case, then ''gravitational wells'' can be seen the other way around... in effect, a well not going down the way, but rather something moving up the way. There is no math describing a thing going down in spacetime to something that is moving upwards/

I prefer to see black holes, mind you, as a well, whilst a normal ripple, pr disturbance, or even to call it a distortion of spacetime nothing more than a wall a thing moves into, mush like we can travel land until we reach a bump. If the gravitation is strong-enough, then we hit a mountain... or a hill manifested by some disturbance in space and time.

You're referring to the rubber sheet analogy? Well, it is just an analogy, after all.

Ok. A slight variation on the same analogy? Things go up?

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The Leif Ericson Cruiser

Yes.... but no...

What goes up in space and time?

Define "up." Are you talking "up" in terms of a "hill" instead of "hole in the ground/depression" rubber sheet analogy?

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I say there is an invisible elf in my backyard. How do you prove that I am wrong?

Disclaimer: Avatar is not an official NASA image and does not imply any specific interplanetary or interstellar capability.

The Leif Ericson Cruiser

Quite right!

In spacetime, you can look down, and it is variably ''up''. Look up, and it is ''down.'' Nothing defines direction in spacetime.

North and South are arbitrary designations in rotational polar orientation. Magnetic fields just let us locate them more easily.

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If you could map a direction in space and time, then we could have a ''bottom'' in this place... however, thee is no bottom. In fact, space and time is isotropic in nature considering directionality.

Tell that to the few around here who seem to think so.

Around where, and who said so?

As for up/down, like everything else about space, they're relative. To an Earthling, Jupiter is "up" even if it's currently on the other side of the planet, because up is oriented from the center of the Earth. To a Jovian, Earth is "up". On the other foot, the person from the first example could just as easily say Jupiter was "down" to them, because they were orienting using their own body instead of the planet, so whatever their feet point towards is "down". And in half a day, when their head was pointing towards Jupiter, they'd call it "up".

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
Illuminati's Razor-The most complicatedly evil answer is usually the most correct answer. - Fazor
"Every book is a children's book if the kid can read." - Mitch Hedberg
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

as for wrinkles in space such as black holes and other bends in the sheet, I think 'in' and 'out' might be more useful then up and down. Yes it is still reletive, but the point of referance is the one you are dealing with at the moment, no reason to get all cosmic about some kind universal referance frame.

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I believe Occams Ghost started this thread because of the reaction he got when he started talking about gravitational "walls" and "barriers" in this thread.

Putting everything together, it looks to me like Occams Ghost prefers his upside-down version of the rubber sheet analogy, and is upset that people are pointing out to him that the conventional version goes the other way and that his version just causes confusion.

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Whenever I picture the rubber sheet analogy in my head- it is utterly different than the rubber sheet analogy. If that makes sense.

Although it can be described as a "well" it is more dimensional than that (if THAT makes sense...) and when I picture it it looks (very hard to describe this part) like a warped well wrapped around the body.

It behaves as a well does- but in any direction. As demonstrated by 3 D bodies in space and even by black holes.

But that doesn't reflect the reality of gravity wells. You have to climb against gravity-- up --to get out of one. You can fall into one-- down.

You can't fall up a hill.

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
Illuminati's Razor-The most complicatedly evil answer is usually the most correct answer. - Fazor
"Every book is a children's book if the kid can read." - Mitch Hedberg
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

Wrong... you can fall into a well, but actually turn up in the correct way... so now how does your arguement hold?

What?

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
Illuminati's Razor-The most complicatedly evil answer is usually the most correct answer. - Fazor
"Every book is a children's book if the kid can read." - Mitch Hedberg
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort

Occams Ghost, aren't you just trying to take the rubber sheet analogy too far? It's an analogy, nothing more. There is no suggestion that gravity really is a depression (or a hill), it's just a way to visualize things in two dimensions to make it simpler to understand. If it doesn't help or confuses, then just forget it. The reality of gravitational theory is much more complex, with tensors and hard maths and stuff. I certainly struggle as soon as I get beyond the pop science.

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Spike
:)

Down is a relative term, it is used relative to the mass with the most gravitational pull on you at the present time. Of course, you could say that the teaspoon that you accidentaly knocked of the table flew up to hit the floor, but that might get you quite a few wierd looks...

Up and down is therefore not without meaning in space, it is just not common to use them when not in close proximity to a massive object... In and out or towards and away would probably be more common when to far away from the object to feel any significant gravitational pull.

By the way, by changing the analogy to a mountain instead of a well, you are not changing the directions involved, it takes energy to climb a mountain, and falling off it releases that energy. So really, moving towards a massive object is less like climbing a mountain than going down the well...

Well. Depending on where you want to be at a spesific time, and what you wish to face, you may want to jump in a well, that might be the correct path, but into the well will always be down, or it's not really a well at all...

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Imagine a black hole... if you enter one, you will appear at a different time in the universe... but what way do you appear? It's like the strange analogy of moving through the earth... if you pass it's center, do you remain with your feet facing australia? No, is the answer, because the force of gravity would keep you at the center... however... in a black hole, you may fall into one, inexorably be sucked by a wormhole threaded with exotic matter, and end up totally the correct way, in a different part of the universe... so a well is really something that you aren't going down, but is a potential tunnel for you to appear in whatever way you had left. But again... there is no up or down. I take no biased opinion either to the rubber sheet.

In fact... the equivalance principle prooves that up and down are irrelevant.

I disagree, in a gravity well up or down (or in and out, same thing, different terms) are VERY important. Going toward the source of the gravity, or away, are quite different things. Ask any pilot, forgetting up or down is a bad thing to do. Now in empty space, yes they are equivalent, but to call them irrelevant is like calling gravity irrelevant because it doesn't happen in empty space.

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