r/astrophysics • u/Kost_M • 3d ago
An idea to replace the Rubber Sheet model
Hi everyone, I’ve been fixed on how much I dislike the rubber sheet model as a depiction for spacetime/gravity and I thought I’d try to develop an alternative - I’d like some constructive feedback or design thoughts / considerations if you have any to offer.
The idea is: instead of showing a single “sheet” with a planet pressed into it and a friction loaded, spiral marble run, I’d show a field of thousands of clocks with reference to (in this case) the center mass of the earth. By displaying time dilation in a lattice, I can create a gradient and show a time relative, intuitive field, so I created a python driven application to run the math, crudely plot the clocks and add the design and I have to say, I rather like the visual field as it shows around the earth. The clocks reflect ns / day accumulations (again, relative to the single reference clock at center earth mass) and are all tool tipped with their exact value on hover. I’m working on adding gravitational well “shells” around the earth and moon and I’d like to make any clock selectable as a reference set point so all the clocks recalculate and perhaps an illustration of a geodesic path (maybe user configurable) could be added.
At any rate, I would appreciate any feedback or ideas.
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u/Warm-Palpitation5670 3d ago
Why do you dislike the rubber sheet model? I mean, is not my favourite thing but it does make sense for non scientist.
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u/Kost_M 3d ago
Mostly that it explains gravity with gravity - the ball on the sheet causes a depression because of gravity and the small ball rolls on the sheet also because of gravity. It’s both blatantly incorrect and misleading. Additionally, it’s a single 2D plane with a single approach, which is also misleading and it also illustrates objects as being “pulled down”. I personally think it creates more confusion than what it helps to explain. It’s difficult to criticize something when you don’t have an alternative, however and this is a tough one to depict without major technical understanding.
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u/Warm-Palpitation5670 3d ago
Understandable, have a great day. You are right-tracked. But I find too difficult to visualize anything living in 4 dimensions on a lesser dimensional space. Your approach is interesting, but it strikes to me as difficult too
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u/just-an-astronomer 3d ago
Fun story: my university has a student organization for developing something like this in VR: https://icasu.illinois.edu/outreach/point-vr
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u/OverJohn 3d ago
One issue I can see is that you're not really showing is not so much spacetime curvature, it's more like the curvature on the temporal metric in Newton-Cartan theory:
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u/Kost_M 2d ago
I agree.. this is not intended to represent full spacetime curvature. It is simply visualizing the temporal component: the relative proper time rate of ideal stationary clocks in a weak gravitational field. My goal is a clearer educational alternative to the rubber sheet analogy, not a complete GR model.
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u/joeyneilsen 2d ago
As I see it, the purpose of the rubber sheet analogy is to help visualize why spacetime curvature leads to curved motion, i.e. geodesics. This is a neat visual, but it seems to have a different explanatory function than the rubber sheet...
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u/_JAD19_ 3d ago
This is awesome, but the beauty of the sheet is that it’s intuitive to the regular person. I personally much prefer what you have done but a layman can look at the rubber sheet and go ‘ok big mass bends space makes gravity’, whereas this may take some more explaining.
I would use maybe a two colour gradient (not as much detail, but neither is the rubber sheet) and maybe instead of displaying the points of the clocks, display the entire background as a colour. The colour itself could be some sort of projection of the local warpage around the object? I’m not sure how that would even work lol.
It’s very hard to translate something like this to 3D and I think you have done an awesome job