Understanding space-time curvature

[Fonceai]

It wasn't an insult.

I was being honest... I didn't want to waste space by explaining something that would just bore those in this thread who have an understanding already.

Speaking of insults, is the "shut up" and the provoking "I guess that means you don't really know" really necessary?

Seems to be showing an "unwillingness to be respectful".

Regardless, do you want me to explain how the forces apply because you don't know, or because you just want to find a way to insult me?

[Technosoul]

For one thing as I noted often before now, we are dealing with circular motion, the circle is the key design for such speculations. Gravity is not curved but is an effect. Planets are attracted towards stars but their speed is also a force factor. That is what causes the orbital effect I think. The speed of the planet or moon forces it away from the object (the sun or another larger object) but the attaction pulls it towards the object, so you get a fixed orbit that maintains a balance between those two factors.

In other words, circular orbits are not just about gravity but are also about speed.

Test. Toss a baseball, the more force used to make the ball go faster the further it will go before falling to the ground, the less power behind the ball the shorter the distance it can go before gravity claims it to become earth bound.

Does that test generate any understanding about the curve of gravity? For the baseball would curve upwards and then downwards when hit by a bat.

This idea no doubt lacks as a total explanation. We put things up into orbit and sometimes their orbital pathway will move them back towards earth and then they burn up on re-entry. To keep them in orbit we use booster rockets to give them more speed. Hmm? If my knowledge about that as a layman is correct?

Other factors would be distance and weight of the orbiting object.

Now about the canyon example. Going around the side of the canyon would seem to be easyer but you allowed a ledge for that purpose which eliminated the effort it would take to fight gravity on your way around the circular edge of the canyon, without that ledge the rolling ball would need lots of speed to make it around from point a to point b otherwise gravity would pull it down to the bottom of the canyon. But if the ball rolled downwards first it would gather enough speed to roll halfway up the other side with little effort, it would seem.

You can test that also in your lab.

But in both cases of the canyon illustration you got a solid mass of substance for the ball to roll around or up and down on. In space the planets do not have such solid canyon walls to roll (like baseballs) on.

A human can bend over without falling flat on his face and no speed in any direction aids that balance. And in fact the balance is aided mainly by our mind and thoughts. It is a conscious effort because if we fainted we would fall flat on our face (or back) because aware thinking keeps us upright.

But it would be rather metaphysical to suggest that planets stay in balanced orbits by conscious effort.

Another interesting things to concider, how is the earth and the sun simular as a gravity influence? The moon orbits the earth like the earth orbits the sun, and one of our spaceships could even orbit the moon. Now at first I thought perhaps that it is the spinning motion of earth around it's own axes that creates the gravity pull somehow. But does the sun spin on it's own axes, or the moon?

Does the presence of those objects cause space to curve around them like a halo around an image of the Virgin Mary? The Arua effect?

An aura of magnetic energy that redates from a planet or star which creates a field of attraction. The bigger the object the bigger the aura and the more influence it would have.

Like a spell that makes men attracted to the ladies if the "vibe" is right.
Which leads to a marrage where their lives evolve around each other "forever and ever". I tossed that in because gravity remains to be sort of a myterious essence that is not unlike "love". Let no one seperate the planets from the sun that have been married by those magical forces of attraction. Okay, that is a bit too poetic ( for the hardcore scientists ).

However space does not curve it is the pathways of the objects that speed around another object. But the arua would be curved if the planet or star is a a globe (circular design). We can image that idea on a foggy night when we see a lighted halo around the moon, caused by water drops of course, but it can give us an idea of what a arua looks like if we could see it with our naked eyes - hard for us to see invisable energy.

Anyway I have tossed together some ideas for concideration and potential elaborations, they are not all "related" to reach the same answer.

[gallo]

It wasn't an insult.

Yes it was.

I was being honest...

No you weren't.

I didn't want to waste space by explaining something that would just bore those in this thread who have an understanding already.

I understand. You don't know.

Speaking of insults, is the "shut up" and the provoking "I guess that means you don't really know" really necessary?

In response to your insult? Yes.

Seems to be showing an "unwillingness to be respectful".

I asked a question and you answered with an insult. Please grow up.

Regardless, do you want me to explain how the forces apply because you don't know, or because you just want to find a way to insult me?

Right. As I thought. You don't know.

[gallo]

I do not buy the straight path through curved space explanation - it is unclear.

Then you give it a try.

No matter how fast an object moves, if it is moving in a straight line (in uncurved space) it follows the same path.

Yes.

However, if you have two objects moving next to a large gravity well, the faster-moving of the two objects will be less affected by the gravity well - it will travel what appears to be a straighter course.

Actually, the acceleration of gravity is the same. Because the faster object is acted on by gravity for a shorter time, the path appears less curved to us.

If it were a straight path, the speed of the object would not affect its course, just how fast it goes through its course.

Right. And how long it is subject to the acceleration of gravity. A free falling object actually accelerates towards the gravity well. Thus, the shorter the time that gravity is able to accelerate the object, the less its path will be bent.

This is a pretty simple objection, and thus I am sure there is just something in the explanation that is confusing, rather than incorrect.

Like I said, the explanation was meant to be simple. It was an imperfect illustration of the concept.

[Captain Chaos]

That's true, but my explanation was not a comprehensive discussion of the relativistic theory of gravitation. Objects moving fast enough would not be caught in orbit. On the other hand, objects moving too slowly would spiral pretty quickly into the star. But that isn't all that relevant to the question and I was trying to keep it simple.

Of course, we could explain it the old way, by Newtonian gravity. A planet near a star is drawn towards the star. At the same time the planet moves sideways so that as it falls it misses the star. Thus it continues to fall around the object in an elipctical path.

Even with orbits, my inability to understand still applies.

If you move faster, you will rise to a higher orbit.

If they are moving in a straight line through curved space, moving faster would just move them faster in a straight line, and thus not change their orbit to higher level.


Whenever I try to get relativity, questions like this arise that I can never find comprehensible answers for. Even discussing them on physics sites has not resulted in an answer that works for me.

This could be a personal failing, of course :)

[Captain Chaos]

Right. And how long it is subject to the acceleration of gravity. A free falling object actually accelerates towards the gravity well. Thus, the shorter the time that gravity is able to accelerate the object, the less its path will be bent.

That makes since, from a Newtonian explanation.


But with the curved space explanation, the object is moving in a straight line. It is not a question of how long it is exposed to gravity. Gravity is curved space. It is simply moving in a straight line - a straight line should be the same, no matter what your speed.

The Newtonian explanation makes perfect sense to me, except that it does not actually explain what gravity is, just describes its effects. 'Course, the newtonian explanation is also demonstrably wrong, and Einstein's explanation has been repeated proven to produce accurate predections.

I still don't get the mechanisms involved though.

Like I said, the explanation was meant to be simple. It was an imperfect illustration of the concept.

I did not mean to refer to your explanation in particular. I meant to refer to the straight line through curved space explanations that I have read in a number of places.

[Captain Chaos]

Yes it was.

Honestly Gallo, you come off pretty rude quite often.

[gallo]

Whenever I try to get relativity, questions like this arise that I can never find comprehensible answers for. Even discussing them on physics sites has not resulted in an answer that works for me.

This could be a personal failing, of course :)

It could be. Or it could be that relativity is incomprehensible in and of itself. It just doesn't relate to the world around you and how you experience that world. The "straight line" and the "curved space" are just metaphors for things that don't lend themselves to expression in everyday terms.

If you think that relativity is bad, then try some quantum mechanics or superstring theory.

[Chris the Chees]

Gallo and Fonceai, if the pair of you can't discuss this topic without telling each other to 'shut up' and dropping other rather impolite remarks, I suggest you leave this thread. This is a site for debate, not for levelling insults and other worthless additions and responses you inaccurately consider appropriate or warranted.

In short, if you can't play nice then get out the sand pit.

[do not respond]

[Captain Chaos]

It could be. Or it could be that relativity is incomprehensible in and of itself. It just doesn't relate to the world around you and how you experience that world. The "straight line" and the "curved space" are just metaphors for things that don't lend themselves to expression in everyday terms.

If you think that relativity is bad, then try some quantum mechanics or superstring theory.

I am better with quantum explanations, especially the ones that say spacetime is granular. That view just makes a lot more sense to me, and provides a reasonable explanation for why time dilation occurs.

Of course, I still don't see any explanation for what gravity is, in quantum physics.

I mean, I realize gravity is included in all of the modern quantum theories, but boy is does it get complicated and subtle at that point.



I like how M brane theory calls for a multiverse, and explains gravity at the same time. It says gravity is a force that is weak locally, but strong because it extends beyond our brane.


And a total aside... brane is not a word in scrabble, and I think it should be added now.

[Autolykos]

Space-time is curved in the sense of distorted. The higher-orbit question has to do with the fact that the distortion follows a gradient.

"Classical" quantum theory states that electromagnetic energy has a certain granularity (i.e. is "quantized"). A quantum theory of gravity would thus state that what we understand as "gravity" -- the distortion of space-time -- has a certain granularity/quantization, too. To unify gravity with electromagnetism, all one would then have to do is prove that the two granularities are either: 1) the same, or 2) related by some function.

Interestingly enough, a quantum theory of gravity would make "anti-gravity" possible, in a way. Gravity would become a part of quantum state. A special phase of matter, the Bose-Einstein condensate, magnifies quantum states on the macroscale. It follows, then, that a certain Bose-Einstein condensate could be constructed such that it provides a local "negation" of Earth's gravity field.

- Rob

[Athena]

Not all moving objects get caught into an orbit.

If you move fast enough past a gravity well, your path will be perturbed, but you will not wind up in orbit.

Your speed will affect the degree to which your path will be perturbed.

This would not be the case if your were moving in a straight line through curved space.

I am not grasping the concepts. It is like trying to understanding the Christian bible or Islam Quran. Things fall from the sky and hit the earth, they do orbit it of fly past once caught in the gravity. I read the gravity of Venus helps pull some of this stuff away from earth, and other stuff is orbiting the sun and doesn't come close enough. But not everything is orbiting is it? And with all the gravity, what keeps the universe from being a black hole?