Could someone explain to me why space/time must be curved. The few examples given in most books do not convince me of its necessity. My opinion is not fixed on this matter. I just need to understand it better first.
Here is what I see wrong withe the examples commonly given.
First a short story.
A long, long time ago, in a universe far far away, there was two planets.
The planet called De Sitter, and the plant Euclid. They share a common history and differ only in their view of the universe.
The planet De Sitter claimed that space was curved, and the shortest path between two points was a curve called a Geodesic line.
The planet Euclid claimed that only the yardstick used to measure space was curved, and the shortest distance between two points is a straight line.
Both have spacecraft that can travel at the speed of light. Planet De Sitter issues a challenge to a space race to decide this once and for all, the loser must stop space travel. Planet Euclid picks the course for the race. It is through a corridor of densely packed stars and planets. Planet De Sitter is pleased with the choice, as gravity and curved space is on their side.
Both ships can travel forward at the speed of light, but they are not the same design. The Euclid ships are equipped with powerful maneuvering thrusters all around. Their computer system uses relativity to calculate the gravitational pull in any direction on the ship, and the gravity is opposed by maneuvering thrusters so that the ship maintains a straight line through space.
The Euclidean ship wins the race hands down because the De Sitter ship must follow a curved, snake like course in the race.
End of story.
The yardstick we use to measure space is itself bent and distorted by gravity as shown by Einstein. But this is not proof that space/time is curved.
The Red Shift is evidence that the universe is expanding, but not proof that space/time is curved.
Let us look at the now famous balloon example, with a twist.
Place the balloon in a vacuum chamber and fill the balloon with hydrogen gas. As you decrease the air density around the balloon, it expands. Atoms within the balloon move away from each other as it tries to keep a uniform density within the balloon. Dots on the balloon will move away from each other also. Yet all this happens within a defined 3 dimensions plus time.
The greater density within our universe causes it to expand into the vacuum around it, while all the energy/matter within it seeks a uniform distribution, just like the gas within our balloon. We see everything moving away from us, even though we are not at the center.
The warping of space is RELATIVE to our frame of referance. If our frame of referance is a rubber yardstick that bends (light), then we percieve that space is bent also. But if we know how much our yardstick is bent, we can correct for it.
QUOTE (Aireal+Jul 13 2007, 01:01 PM)
The yardstick we use to measure space is itself bent and distorted by gravity as shown by Einstein. But this is not proof that space/time is curved.
The Red Shift is evidence that the universe is expanding, but not proof that space/time is curved.
You are of course right that there is no proof that space is curved. Which is why I often suggest the possibility that space may not be tangible at all. People rarely ever consider this possibility, because it would have egregious ramifications for not just Physics itself, but for the possible methods which we could ever use to travel to other stars. It would certainly throw out such things as warp and wormholes.
The Red Shift is evidence that the universe is expanding, but not proof that space/time is curved.
You are of course right that there is no proof that space is curved. Which is why I often suggest the possibility that space may not be tangible at all. People rarely ever consider this possibility, because it would have egregious ramifications for not just Physics itself, but for the possible methods which we could ever use to travel to other stars. It would certainly throw out such things as warp and wormholes.
The shortest distance between two points is a straight line. Energy flow always takes the path of least resistance. Even a curved path taken by light then would represent the path of least resistance, or in effect the straightest line possible between the two points.
I remember a talk on TV in the nineteen fifties by Einstein. In this talk he explained spacetime curvature as neccessary to explain the infinity of space. Instead of space being neverending in one direction his explanation was that a journey in one direction would eventually return you to the point of departure eliminating the incomprehensible concept of an infinite or neverending space.
Okay, I think there are two different concepts here.
One concept is whether the universe is bounded (i.e. is an expanding hypersphere like the balloon model) vs being only 3 dimensions which continue forever in all 3 directions.
The other concept is how gravity works. In regards to this, "curved" space is what we use to show on a 2D picture that space-time is more dense in areas of large mass. In actuality, the word "curved" is a misnomer because reality is not a 2D picture. Space is denser. The alternative to this theory is that space is immaterial (like Bryn mentioned), and that gravity is the result of something else.
One concept is whether the universe is bounded (i.e. is an expanding hypersphere like the balloon model) vs being only 3 dimensions which continue forever in all 3 directions.
The other concept is how gravity works. In regards to this, "curved" space is what we use to show on a 2D picture that space-time is more dense in areas of large mass. In actuality, the word "curved" is a misnomer because reality is not a 2D picture. Space is denser. The alternative to this theory is that space is immaterial (like Bryn mentioned), and that gravity is the result of something else.
Hello all
Mass slows down time in its vicinity. Time is part of the space-tome we all inhabit. The local curve of space time can be related to the the gradient between the "slower" time around mass to the "faster" time in open space.
This is just one of many explanations for the curvature of space.
Mass slows down time in its vicinity. Time is part of the space-tome we all inhabit. The local curve of space time can be related to the the gradient between the "slower" time around mass to the "faster" time in open space.
This is just one of many explanations for the curvature of space.
QUOTE (fizzeksman+Jul 13 2007, 04:40 PM)
eliminating the incomprehensible concept of an infinite or neverending space.
I don't think it's so incomprehensible.
I don't think it's so incomprehensible.
Nice to see so many responses on this subject, I have sent some time on it myself, which is why I asked the question.
Bryn Richards
I can find no proof that space/time is curved. The poor examples usually given are insufficient and lacking in logic. So I must consider the possibility that space/time is not curved. Regardless of the ramifications for Modern Physics.
Fizzeksman
I wish I had seen that show. I have read his work, but not ran across anything similar to in in them. Rather than explaining the infinity of space, it does the opposite. Thus curved space is not infinite, it only appears to be so. Personally, I have never had a problem comprehending infinite space, and have no need to confine it to a ball so I can comprehend it.
Latrosicarius
Yes there are two different concepts here, but they are linked, and both examples have been used to "prove" curved space/time.
So I had to address both of these "examples" in my question. The varying density of space, time, and mass dilation can all be explained without the concept of curved space/time. Doing so only returns us to the old concept that space is infinite in 3 dimensions, not a problem.
Montec
Like I told Latrosicarius, the time and mass dilation's can be accounted for without the concept of curved space/time, therefore they can not be proof of curved space/time if there are other methods that will work. The gravity waves described can account for all this. Curved space/time is just a replacement of the Aether for these gravity waves, and so far, no more provable.
The famous Lorentz contraction of matter and time was introduced to explain the null result of the Michelson - Morley experiment and later applied to relativity. Thus it can be applied to wave theories just as well. Here are Einstein's comments on it. "Lorentz and FitzGerald rescued the theory from this difficulty by assuming that the motion of the body relative to the Aether produces a contraction of the body in the direction of motion...also from the standpoint of the theory of relativity this solution of the difficulty was the right one." Einstein Relativity The Special and the General Theory
As relativity shows, a gravitational field and acceleration are the same, so a time/matter dilation will be seen depending on proximity to the center of mass. The time/matter dilation's can be explained by simple wave mechanics. That should come as no surprise as it was developed for the Aether model.
I do not wish to distract from the great achievement of relativity and special relativity. But I can take out curved space/time and replace it with an Aether concept and get the same results. Or even say that gravity waves do not need a medium of propagation and do away with both concepts.
So before I accept the concept of Curved Space/Time, I require some meager proof that it may be right. So far that proof has not been forthcoming.
Charles
Bryn Richards
I can find no proof that space/time is curved. The poor examples usually given are insufficient and lacking in logic. So I must consider the possibility that space/time is not curved. Regardless of the ramifications for Modern Physics.
Fizzeksman
I wish I had seen that show. I have read his work, but not ran across anything similar to in in them. Rather than explaining the infinity of space, it does the opposite. Thus curved space is not infinite, it only appears to be so. Personally, I have never had a problem comprehending infinite space, and have no need to confine it to a ball so I can comprehend it.
Latrosicarius
Yes there are two different concepts here, but they are linked, and both examples have been used to "prove" curved space/time.
So I had to address both of these "examples" in my question. The varying density of space, time, and mass dilation can all be explained without the concept of curved space/time. Doing so only returns us to the old concept that space is infinite in 3 dimensions, not a problem.
Montec
Like I told Latrosicarius, the time and mass dilation's can be accounted for without the concept of curved space/time, therefore they can not be proof of curved space/time if there are other methods that will work. The gravity waves described can account for all this. Curved space/time is just a replacement of the Aether for these gravity waves, and so far, no more provable.
The famous Lorentz contraction of matter and time was introduced to explain the null result of the Michelson - Morley experiment and later applied to relativity. Thus it can be applied to wave theories just as well. Here are Einstein's comments on it. "Lorentz and FitzGerald rescued the theory from this difficulty by assuming that the motion of the body relative to the Aether produces a contraction of the body in the direction of motion...also from the standpoint of the theory of relativity this solution of the difficulty was the right one." Einstein Relativity The Special and the General Theory
As relativity shows, a gravitational field and acceleration are the same, so a time/matter dilation will be seen depending on proximity to the center of mass. The time/matter dilation's can be explained by simple wave mechanics. That should come as no surprise as it was developed for the Aether model.
I do not wish to distract from the great achievement of relativity and special relativity. But I can take out curved space/time and replace it with an Aether concept and get the same results. Or even say that gravity waves do not need a medium of propagation and do away with both concepts.
So before I accept the concept of Curved Space/Time, I require some meager proof that it may be right. So far that proof has not been forthcoming.
Charles
QUOTE (Aireal+Jul 14 2007, 11:55 AM)
Bryn Richards
I can find no proof that space/time is curved. The poor examples usually given are insufficient and lacking in logic. So I must consider the possibility that space/time is not curved. Regardless of the ramifications for Modern Physics.
Wow, great, that's all I ever ask people to do
If only more people were capable of the same...
I can find no proof that space/time is curved. The poor examples usually given are insufficient and lacking in logic. So I must consider the possibility that space/time is not curved. Regardless of the ramifications for Modern Physics.
Wow, great, that's all I ever ask people to do
If only more people were capable of the same...
I think spacetime is curved because I believe that Gravity is the curvature of spacetime.
- Gizmo
- Gizmo
If spacetime is expanding our universe, that is, if we accept a closed spacetime, how fast does it do it? And does it follow our laws? If it does, shouldn't it create gravity phenomena at its forefront as it grows? Shouldn't we see signs of that. Now i know we can't measure gravity other than indirect but shouldn't it be possible to locate such effects? On the other hand. If one accept the big bang the universe expanded faster than light in the beginning, right? Are it still doing so or have it slowed down, if it has, i wonder why, as it didn't seem to follow any known laws before. And if it still does there are the infinite universe :)
Doesn't this prove closed spacetime ?
http://www.itwire.com.au/content/view/11350/1066/
" Einstein’s General Theory of Relativity is a theory that predicts gravitation is not due to an attractive force but instead is a consequence of the distortion of space and time (that is, the curvature of space-time), specifically by the mass-energy and momentum content of space-time. In other words, Einstein did not see, for example, the solar system’s planets being pulled in by the Sun. Instead, he saw them following the curvedness of space-time due to the distorting effects of the Sun’s mass."
http://www.itwire.com.au/content/view/11350/1066/
" Einstein’s General Theory of Relativity is a theory that predicts gravitation is not due to an attractive force but instead is a consequence of the distortion of space and time (that is, the curvature of space-time), specifically by the mass-energy and momentum content of space-time. In other words, Einstein did not see, for example, the solar system’s planets being pulled in by the Sun. Instead, he saw them following the curvedness of space-time due to the distorting effects of the Sun’s mass."
Yor on
Actually it kinda makes my point. Yes it is proof that space/time is curved. However, curved space/time was just a replacement for the Aether. Curved space/time can be replaced with a Aether, and get the same results in euclidean space. Both predict GEODETIC EFFECT, which is movement along a geodesic path through space. Both predict FRAME-DRAGGING, which is the amount the rotating Earth drags local, space/time or the Aether, take your pick.
So if two opposing theories can give the same result of an observation, there is no way to know which is true for sure. Space/time may be curved, and it may not be, you can prove it both ways.
Actually it kinda makes my point. Yes it is proof that space/time is curved. However, curved space/time was just a replacement for the Aether. Curved space/time can be replaced with a Aether, and get the same results in euclidean space. Both predict GEODETIC EFFECT, which is movement along a geodesic path through space. Both predict FRAME-DRAGGING, which is the amount the rotating Earth drags local, space/time or the Aether, take your pick.
So if two opposing theories can give the same result of an observation, there is no way to know which is true for sure. Space/time may be curved, and it may not be, you can prove it both ways.
QUOTE (yor_on+Jul 15 2007, 06:09 AM)
Doesn't this prove closed spacetime ?
http://www.itwire.com.au/content/view/11350/1066/
No it does not.
All they did was send some balls into space, and measured some minor changes in angle/alignment. This is not verification of the existence of a 'space-time'. It is verification that there was 'some effect' which influenced the balls.
I think this may turn into another time dilation GPS style thing
I'm just thoroughly not convinced by these experiments. They're always trying to measure some effect down to a high degree of accuracy, and I believe that they are not accounting for all external/internal influences.
You wanna prove space-time exists? - Give me some 'positive evidence' - Go open a bloody rip in space-time, or warp it for me, or show me a sodding wormhole!
Don't send some satellite into space to try and measure some minuscule differences which nobody can be certain aren't being caused by other phenomena.
http://www.itwire.com.au/content/view/11350/1066/
No it does not.
All they did was send some balls into space, and measured some minor changes in angle/alignment. This is not verification of the existence of a 'space-time'. It is verification that there was 'some effect' which influenced the balls.
I think this may turn into another time dilation GPS style thing
I'm just thoroughly not convinced by these experiments. They're always trying to measure some effect down to a high degree of accuracy, and I believe that they are not accounting for all external/internal influences.
You wanna prove space-time exists? - Give me some 'positive evidence' - Go open a bloody rip in space-time, or warp it for me, or show me a sodding wormhole!
Don't send some satellite into space to try and measure some minuscule differences which nobody can be certain aren't being caused by other phenomena.
let me see if i get this straight. In your aether theory this proof of a closed spacetime can only be a proof of " GEODETIC EFFECT, which is movement along a geodesic path through space. Both predict FRAME-DRAGGING, which is the amount the rotating Earth drags local, space/time or the Aether " So in that theory there are no closed spacetime at all? Or is it that you accept this as proof on a closed spacetime but that your theory also are supportive of those evidence?
Yor on
I am not sure on what path my theory should follow. Aether, a wave medium, or curved time/space, a wave medium. Both paths will give my theory the same results. So how do I choose?
I need some other proof, one direction or another, I just have not found it yet.
Bryn Richards
I have an Internet friend, some of his posts are on this forum, who may solve this. Mansouryar is a brilliant young man the press has called, "The next Einstein". He is not happy with that title, but jokes about it. He is a firm believer in curved space time. His work shows how to construct a wormhole, among other things. He was working on this before the whole stargate show thing by the way. His work may be the key to proving or disproving curved space/time. Here is a link to his site. http://www.mansouryar.com/
So I do have friends with very mainstream beliefs. We just don't let our theories get in the way of being friends. I wish him luck, and expect great things from this young man, regardless if his project works or not.
Charles
I am not sure on what path my theory should follow. Aether, a wave medium, or curved time/space, a wave medium. Both paths will give my theory the same results. So how do I choose?
I need some other proof, one direction or another, I just have not found it yet.
Bryn Richards
I have an Internet friend, some of his posts are on this forum, who may solve this. Mansouryar is a brilliant young man the press has called, "The next Einstein". He is not happy with that title, but jokes about it. He is a firm believer in curved space time. His work shows how to construct a wormhole, among other things. He was working on this before the whole stargate show thing by the way. His work may be the key to proving or disproving curved space/time. Here is a link to his site. http://www.mansouryar.com/
So I do have friends with very mainstream beliefs. We just don't let our theories get in the way of being friends. I wish him luck, and expect great things from this young man, regardless if his project works or not.
Charles
Good debate going on here...
QUOTE (Aireal+)
He is a firm believer in curved space time. His work shows how to construct a wormhole, among other things. He was working on this before the whole stargate show thing by the way. His work may be the key to proving or disproving curved space/time.
At the moment, it's all talk, no tangibility.
Yor on,
Bryn and Aireal are correct. Gravity Probe B proves that the mass of the Earth causes the same gravitational effects that General Relativity predicts. It does not mean that those effects are caused by "curved space-time".
Personally, I think that space probably does curve, but such a notion could never actually be proven, because it's not directly observable--only its effects are.
Bryn and Aireal are correct. Gravity Probe B proves that the mass of the Earth causes the same gravitational effects that General Relativity predicts. It does not mean that those effects are caused by "curved space-time".
Personally, I think that space probably does curve, but such a notion could never actually be proven, because it's not directly observable--only its effects are.
Yeah, that' my thought too :)
Btw: Aireal , that link you gave to Mansourya's work seems interesting :)
Btw: Aireal , that link you gave to Mansourya's work seems interesting :)
PhysOrg scientific forums are totally dedicated to science, physics, and technology. Besides topical forums such as nanotechnology, quantum physics, silicon and III-V technology, applied physics, materials, space and others, you can also join our news and publications discussions. We also provide an off-topic forum category. If you need specific help on a scientific problem or have a question related to physics or technology, visit the PhysOrg Forums. Here you’ll find experts from various fields online every day.
To quit out of "lo-fi" mode and return to the regular forums, please click here.