No No No. The demo is a model of how the force of gravity can be considered in terms of spacetime curvature.
Nobody is saying that gravity does not exist. Gravity is the effect of spacetime curvature. GR provides a geometric explanation of what actually underlies the force of gravity.
Which is it? Is gravity a force? Or some geometric curvature of space-time? Do you really believe that there is a thing that exists out in space that is being warped by objects. In order for this whole idea of space-time to make any logical sense there would have to be some evidence that this fabric actually exists. There is none. So why is it even taken seriously? Has the whole essence of scientific research been reduced to beliefs and unquestioning acceptance of what we are told is true?
There is no direct evidence in the existance of this space-time fabric.
No it is a classroom model used for explanatory purposes. In the same way I can model the solar system with a bowling ball, an orange and some grapes nobody is claiming this is "proof" of the structure of the solar system!!!
Making a model of the solar system is taking those things that are observable (the planets and the sun) and replacing them with other objects so as to show the relationship of where these objects are located and their relative sizes to each other. You are taking what is already a know physical object and replacing it with a different known physical object for the purposes of demonstration.
Now when it comes to this space-time fabric being represented as an elastic sheet, how does that elastic sheet compare to the real space-time fabric? What is similar between them? Their shape? The fact that the elastic sheet has to be secured at the edges in order to support the mass?
If you want to make a great demo of this space-time thing, then take that elastic sheet and stretch it out and then pass a mass over the sheet and show that the presence of mass can warp this sheet without even coming in contact with it. That would be a start in the right direction in showing some evidence of this fabric that exists in outer space.
In the all of the demos of this space fabric, the mass is placed on the elastic sheet by a human, and gravity pulls it down.
This whole belief that there is some cosmic fabric that exists in space is bordering on an almost religious belief. Where is the hard cold science that provides any shred of evidence in the physical existance of this cosmic fabric?
The demo proves nothing and is not intended to prove anything.
Evidence for GR comes in the form of gravitational lensing, GPS satellite time differences etc. etc. etc.
Predicted calculated results that have been experimentally verified. Repeatedly.
What was even your point in bringing this demo up in the first place? What has it done for this discussion? What were you trying to add to this subject?
Look, I am not trying come across as someone who is antagonistic toward you, I have just heard so many people discuss this cosmic fabric as though it is a real thing and I am in the wrong for not not believing in this Great fabric in the sky.
Evidence for GR comes in the form of gravitational lensing, GPS satellite time differences etc. etc. etc.
Evidence for GR? I have been asking for evidence that space is a physical thing, and this is what you are giving as evidence.
We can discuss GR at a latter time, but lets get back to the basic question. Is there any evidence that space is a physical thing.
The concept of space is what holds all of your statements and demos of space-time and the such together. If space is not a real physical thing where does that leave GR and SR? So there must be some direct evidence in the idea that space is a real physical thing.
Once it has been established that space is a real physical thing and not just an assumption, then we can discuss all of those things that are supposed to be made from it.
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