Gravitational Wells

[Ian]

I am a bit skeptical about Gravitational wells. If the sun has a gravtitational well, then the planets should have them too. If the planet's gravitational wells are connected together, shouldn't they somehow remain stationary? That's why I'm not sure whether or not the gravitational well theory is correct. If the theory about gravitational wells is incorrect what about gravitational fields? What makes up gravitational fields?

[Stimpson J. Cat]

Ian,

I am a bit skeptical about Gravitational wells. If the sun has a gravtitational well, then the planets should have them too. If the planet's gravitational wells are connected together, shouldn't they somehow remain stationary?

No. Why would you think so?

Dr. Stupid

[Ian]

That little comment "Dr. Stupid" wasn't very mature.

[slimshady2357]

Originally posted by Ian
That little comment "Dr. Stupid" wasn't very mature.

I doubt it was meant that way :)

How can he correct your opinion when you give no details?

Why do you think that "If the planet's gravitational wells are connected together, shouldn't they somehow remain stationary"?

If you explain why you think that is the case, Dr Stupid can give you a much better response, one that pinpoints (in his opinion) where your thinking has gone wrong.

This would not only be more informative to you, but also to the rest of us watching.

Adam

[Ian]

If space is like a big sheet of rubber or something that can have dents in it that make planets and other massive bodies sort of fall into them, then the sun's Gravitational Field could bend, or warp space and time around it. So shouldn't all the planets in the solar system have gravitational wells? Look what happens to the moon. Another theory is gravitational fields. One of those theorys can't entirely be correct. It looks as though those two theorys are competing with each other. Could someone explain how they are attempting to explain the same observations of the behavior of gravity? If they both are attempting to explain the same thing, then one is wrong. Both can't be right. Please reply.

[Brian the Snail]

Originally posted by slimshady2357


I doubt it was meant that way :)

How can he correct your opinion when you give no details?

Why do you think that "If the planet's gravitational wells are connected together, shouldn't they somehow remain stationary"?

If you explain why you think that is the case, Dr Stupid can give you a much better response, one that pinpoints (in his opinion) where your thinking has gone wrong.

This would not only be more informative to you, but also to the rest of us watching.

Adam

If I can butt in, I think it was a genuine mistake on Ian's part. I think he simply saw "Dr Stupid" at the end of the post, and thought that it was an insult directed at him. He doesn't realise that Stimpy signs off as "Dr Stupid" at the end of every post he makes.

Don't worry, Ian, no harm done. :)

[slimshady2357]

Originally posted by Brian the Snail


If I can butt in, I think it was a genuine mistake on Ian's part. I think he simply saw "Dr Stupid" at the end of the post, and thought that it was an insult directed at him. He doesn't realise that Stimpy signs off as "Dr Stupid" at the end of every post he makes.

Don't worry, Ian, no harm done. :)

Oh ya, sure, I never thought of that :)

I thought he was addressing Stimpy and saying his curt answer was immature.

But I see what you mean, perhaps he thought the 'Dr. Stupid' was directed at him.

Stimpy almost always signs off as Dr. Stupid, as you noted. :)

Adam

[Crossbow]

Ian:

OK, I will attempt to answer your question.

The sun generates a gravitational field, which in some contexts is described as a gravity well. And this gravity does cause variations in space-time as theorized by the General Theory of Relativity.

The same thing happens (but to a much lesser scale) with planets. And in fact, anything with mass will generate gravity and thus one of those gravity wells. But practically speaking, since the force of gravity is so weak, it takes a rather substantial amount of mass to generate any noticeable amount of gravity and a gravity well of any real influence.

OK so far?

Now then, since gravity is such a weak force, and since its magnitude drops off with the square of the distance between the objects in question, gravity will not be able to stop all motion, therefore there is no conflict between the motion of objects and the influence of gravity.

By the way, Stimpson J. Cat is a Ph. D. physicist and is very knowledgeable about matters of science and he signs all of his posts with 'Dr. Stupid' which is a reference to an episode of 'Ren & Stimpy'.)

I hope this helps!

[Dorman]

If space is like a big sheet of rubber or something that can have dents in it that make planets and other massive bodies sort of fall into them, then the sun's Gravitational Field could bend, or warp space and time around it. So shouldn't all the planets in the solar system have gravitational wells?


So they should.... Then ??
(Nothing forces these ``wells'' to be stationary. They will move with the planets. Perhaps this is the point of confusion.)



Look what happens to the moon.

I do not understand the connection with the moon :confused:



Another theory is gravitational fields. One of those theorys can't entirely be correct. It looks as though those two theorys are competing with each other. Could someone explain how they are attempting to explain the same observations of the behavior of gravity? If they both are attempting to explain the same thing, then one is wrong. Both can't be right. Please reply.

A gravitational field can be expressed in terms of a gravitational potential. A `gravitational well' is just the region where the gravitational potential has a local minimum.

So why do you think the gravitational fields and wells contradict each other ?

[Stimpson J. Cat]

Ian,

That little comment "Dr. Stupid" wasn't very mature.

As others have pointed out, I sign all my posts with "Dr. Stupid". It is a reference to Ren & Stimpy.

Anyway, the comment wasn't intended in a derogatory way. It is clear that something is wrong with your understanding of gravity. Your post does not reveal where the problem lies. There is therefore no way for me to address the problem, other than to try to explain gravitational theory from the ground up. As Slimshady suggested, I need to know why you think that gravitational wells should remain stationary before I can explain the flaw in your reasoning.

If space is like a big sheet of rubber or something that can have dents in it that make planets and other massive bodies sort of fall into them, then the sun's Gravitational Field could bend, or warp space and time around it. So shouldn't all the planets in the solar system have gravitational wells? Look what happens to the moon.

Yes, they do.

Another theory is gravitational fields. One of those theorys can't entirely be correct. It looks as though those two theorys are competing with each other. Could someone explain how they are attempting to explain the same observations of the behavior of gravity? If they both are attempting to explain the same thing, then one is wrong. Both can't be right. Please reply.

I think maybe what you are mixing up here is the old gravitational field conception from Newtonian mechanics, with the newer General Relativistic conception of gravity in terms of space-time curvature. In that sense, you are correct. The two theories cannot both be right. They are not both right. General relativity appears to be correct, and the Newtonian theory of gravitational fields is just very accurate under "normal" conditions, meaning velocities small compared to the speed of light, and gravitational fields which are very week compared to those near a black hole.

Crossbow,

One detail: I am a physicist, but not a nuclear physicist. My field of specialization is nonlinear dynamics and stochastic processes.


Dr. Stupid

[Crossbow]

Stimpy:

Thanks for the correction and I updated my above post accordingly.

By the way, do you work with Q-plasmas?

[Ian]

What happens to spacetime when the planet's and the sun's
gravitational wells move when the planets orbit the sun
and the sun orbits around the center of the milky way
in it's spiral arm? Does spacetime get distorted because
of these gravitational wells? If it does, then how does it
get distorted?

[The Don]

Gravitational wells are formed as distortions in the Spacetime continuum (the rubber sheet to which you refer) by any mass. Because masses have, well... mass, they will exert a force on other masses and subject them to accelleration which will in turn result in relativistic effects (the twins paradox describes these effects http://www.cix.co.uk/~antcom/tp.html).

Everything does this but the effects are tiny any so you only get measurable effects, distortions, when you get to large masses such as a star, black hole or indeed my mother in law.

What happens to spacetime when the planet's and the sun's
gravitational wells move when the planets orbit the sun
and the sun orbits around the center of the milky way
in it's spiral arm?

Spacetime gets distorted at those locations in spacetime

Does spacetime get distorted because
of these gravitational wells?

In a way, yes, it gets distorted because of the masses involved

If it does, then how does it get distorted?

It gets distorted by the masses involved

[Stimpson J. Cat]

Ian,

What happens to spacetime when the planet's and the sun's gravitational wells move when the planets orbit the sun and the sun orbits around the center of the milky way in it's spiral arm? Does spacetime get distorted because of these gravitational wells?

Yes, that is exactly what happens.

If it does, then how does it get distorted?

It gets distorted according to Einstein's equations of General Relativity. This is a set of partial differential equations which describe how the distortion in space-time caused by moving and accelerating masses, propagates through space.

These propagating distortions manifest as gravitational waves, which are far too weak to be detected under normal conditions, but which play a significant role in Cosmological models.


Dr. Stupid

[Ian]

What in mathametics do the variable that looks like a
hugh E in something like italics mean? And also, what
does the varible that looks like a huge skinny S mean?
Please reply.

[jj]

Originally posted by Ian
If space is like a big sheet of rubber or something that can have dents in it that make planets and other massive bodies sort of fall into them, then the sun's Gravitational Field could bend, or warp space and time around it. So shouldn't all the planets in the solar system have gravitational wells? Look what happens to the moon. Another theory is gravitational fields. One of those theorys can't entirely be correct. It looks as though those two theorys are competing with each other. Could someone explain how they are attempting to explain the same observations of the behavior of gravity? If they both are attempting to explain the same thing, then one is wrong. Both can't be right. Please reply.

Ian, even the pencil on your desk has a gravity well. Not a very big one, of course, but it has one.

Since mass can move, the gravity wells can move. Now, perhaps you can ask why inertia happens. :)

[jj]

Originally posted by Stimpson J. Cat
Ian,
One detail: I am a physicist, but not a nuclear physicist. My field of specialization is nonlinear dynamics and stochastic processes.
Dr. Stupid

You work on sadistic processes? Cool. I'll bet you could digest some of the coding stuff I've done in a few seconds, then. :)

Nonlinear dynamics? You mean the vocal tract?

[jj]

Originally posted by Ian
What in mathametics do the variable that looks like a
hugh E in something like italics mean? And also, what
does the varible that looks like a huge skinny S mean?
Please reply.

I believe you're talking about a capital Sigma, which is the operator expression for sumation, and the integral sign, which is the operator indicating integration.

I suspect you're going to need a good math book. In some other thread, I think I mentioned a good "History of Math" book. If you find that thread, and get the book, it may help this discussion enormously. You'll have to plow through it.

(Note, Ian, nobody said the math was simple... Sorry.)

[Dancing David]

And I thought I could drop a bucket into the gravity well and pull up some gravity, darn.

The cool thing about the distortion of space is that we can't percieve it directly, the rubber sheet does not become more inelastic as you strect it, so you can have the elephant of the galaxy walking on the sheet, the rhinos of the stars, the dogs and cats and hamsters of planets and the mice of moons and the insects of planetoids. They all create thier own proportionate dimple in the already streched fabric of space time.

SoWhat does cause inertia?

That is truely a great question, is it the vacuum energy and the virtual particles?

and

Why does the mass of objects increase as they approach the speed of light?

Thanks

[DanishDynamite]

Ian, welcome to the Science forum. :)

Just a small note: It is generally seen as good manners to reply directly (preferably with quotes) to the people responding to your questions.

Hope you have fun learning here. We have some very knowledgable posters cruising the forum.