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ryanvb03
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I know the general theory as proposed by Einstein but how has it been proved beyond a reasonable doubt?
ryanvb03 said:I know the general theory as proposed by Einstein but how has it been proved beyond a reasonable doubt?
Actually, that wording is incorrect. It should be "how do we know space and time are just facets of a single entity called spacetime?"ryanvb03 said:IHow do we know space and time are related?
Fredrik said:Also, you don't prove a theory beyond reasonable doubt. All you can do is find out how accurate the theory's predictions are. This way you can prove beyond a reasonable doubt that a theory's predictions are much better than the predictions of some older theory.
phinds said:Actually, that wording is incorrect. It should be "how do we know space and time are just facets of a single entity called spacetime?"
That is, they are not "related" they are parts of a single thing.
bobc2 said:that would seem to imply a block universe (the universe is a 4-D space-time that is "all there at once" as a single entity).
bobc2 said:It has been emphasized over and over here that it is not possible to know that there is a single entity called space-time. Forum members have been given demerits for asserting this, and not long ago Vandam was removed from the forum for persisting in maintaining that the universe exists as a 4-dimensional entity.
PeterDonis said:I don't think it necessarily implies that.
PeterDonis said:But more importantly, since neither you nor anyone else has been able to state any experimental results that would be different on the block universe interpretation vs. another interpretation, the question of whether the block universe interpretation is correct is a philosophical question, not a scientific question.
I think you are making the mistake of assuming that "4D spacetime" is the same thing as, or implies, a "block universe". I've never fully understood what the "block universe" is supposed to be, but it seems to be more that just 4D spacetime; it seems to have some extra interpretation in terms of eternalism or determinism or something. I don't think anyone here would argue against the mathematical model of spacetime, without any "block" philosophy.bobc2 said:phinds, that would seem to imply a block universe (the universe is a 4-D space-time that is "all there at once" as a single entity). It has been emphasized over and over here that it is not possible to know that there is a single entity called space-time. Forum members have been given demerits for asserting this, and not long ago Vandam was removed from the forum for persisting in maintaining that the universe exists as a 4-dimensional entity.
phinds said:Actually, that wording is incorrect. It should be "how do we know space and time are just facets of a single entity called spacetime?"
That is, they are not "related" they are parts of a single thing.
bobc2 said:The statement was: ..."That is, they are not "related" they are parts of a single thing."
bobc2 said:in other posts I have presented a summary of a proof related by Paul Davies in his book, "About Time." Neither you nor anyone else has presented an argument that directly refutes that proof.
PeterDonis said:since neither you nor anyone else has been able to state any experimental results that would be different on the block universe interpretation vs. another interpretation, the question of whether the block universe interpretation is correct is a philosophical question, not a scientific question.
...
what people have been given "demerits" for is insisting that the question of whether the block universe interpretation is correct is a scientific question, without being able, as I said above, to give any way of resolving it by experiment. That doesn't mean it's a meaningless question, but it does mean there's no point in discussing it in a forum that's supposed to be for discussing scientific questions.
phinds said:Actually, that wording is incorrect. It should be "how do we know space and time are just facets of a single entity called spacetime?"
That is, they are not "related" they are parts of a single thing.
Maybe so; however I find Bob's reaction normal. Phinds made the strange claim that they (space and time) are not "related". However, the LT express just how those two things are related.PeterDonis said:Yes, and that's not the same as saying the block universe interpretation is true, which is what you [Bob] were claiming.[..]
harrylin said:Phinds made the strange claim that they (space and time) are not "related". However, the LT express just how those two things are related.
Maybe so, but that still smells like philosophy. For example the LT permit to calculate the time on a clock and the proper length of a ruler, which are certainly separate and very different things that no physicist will confound. Of course, endless philosophical discussions have been held and continue to be held about such things as the nature of space and time. I think that such things are counterproductive for the topic here, which is about the predictions of the theory.PeterDonis said:Not exactly. Here's how I read phinds' statement (he's welcome to correct me if I'm wrong): space and time aren't "related" because "related" implies that they are two separate things with a relationship between them. But the whole point of the math of LT's is that there is no one single unique way to split up spacetime into "space" and "time"; saying "space and time are related" implies that there is. It's better to say "space and time are parts of a single thing, spacetime".
But even the latter way of stating it can still be misleading. I would phrase it like this: "space" and "time" are observer-dependent ways of splitting up "spacetime". We feel an intuitive desire to do this splitting because our minds are structured to perceive "space" and "time" as two separate things. But our minds are also structured to assume that there is one, unique, absolute way to do the splitting, and there isn't. So in our physical theories, we don't treat the splitting as fundamental; the fundamental thing is spacetime, a single thing, not "space" and "time". We only put in the splitting if it helps to match up the theory with our observations, and when we do, we have to do it in a way that recognizes the observer-dependence of the splitting. Hence the math of LTs.
(Note, btw, that if you only deal with spacetime and geometric entities in spacetime, you never have to use LTs at all. You can express all of the physics without ever doing a Lorentz transformation.)
harrylin said:Maybe so, but that still smells like philosophy.
harrylin said:For example the LT permit to calculate the time on a clock and the proper length of a ruler
harrylin said:which are certainly separate and very different things that no physicist will confound.
harrylin said:endless philosophical discussions have been held and continue to be held about such things as the nature of space and time. I think that such things are counterproductive for the topic here.
PeterDonis said:Not exactly. Here's how I read phinds' statement (he's welcome to correct me if I'm wrong): space and time aren't "related" because "related" implies that they are two separate things with a relationship between them. But the whole point of the math of LT's is that there is no one single unique way to split up spacetime into "space" and "time"; saying "space and time are related" implies that there is. It's better to say "space and time are parts of a single thing, spacetime".
Thanks for the clarification! And most likely the OP used the words in a different way which is also correct. Hopefully Ryan is still on board...phinds said:Yes, that is exactly what I was saying (or at least intending to convey) and I do not see that as being at all a "philosophical" point of view but rather a purely scientific one.
Scientists have discovered through numerous experiments and observations that space and time are closely intertwined. Einstein's theory of relativity, specifically the theory of general relativity, explains how space and time are connected through the fabric of spacetime. In this theory, gravity is not a force between objects, but rather a curvature in the fabric of spacetime caused by the presence of massive objects.
The theory of relativity, proposed by Albert Einstein, states that the laws of physics are the same for all observers in any inertial frame of reference. This means that the speed of light is constant for all observers, regardless of their relative motion. The theory also explains how gravity is not a force between objects, but rather a result of the curvature of spacetime caused by massive objects. This shows the close relationship between space and time.
Yes, there have been several experiments that demonstrate the relationship between space and time. One of the most famous is the Hafele-Keating experiment, which showed that time is relative and can be affected by velocity. Another experiment, the Pound-Rebka experiment, demonstrated the effects of gravity on the passage of time. Both of these experiments support Einstein's theory of relativity and the connection between space and time.
Yes, there is ample evidence that supports the existence of spacetime. One of the most significant pieces of evidence is the observation of gravitational lensing, which is the bending of light by massive objects. This phenomenon can only be explained by the curvature of spacetime predicted by the theory of general relativity. Additionally, precise measurements of the orbits of Mercury and other planets in our solar system also support the idea of spacetime.
The concept of spacetime has greatly impacted our understanding of the universe. It has allowed scientists to explain and predict the behavior of objects in the universe, from the smallest particles to the largest galaxies. It has also led to the development of technologies such as GPS, which relies on the precise understanding of the relationship between space and time. Additionally, the concept of spacetime has opened up new avenues for research and exploration, such as the study of black holes and the search for gravitational waves.