3 ms·
Spacetime is just 4D array: [x,y,z;t]. "Bending of spacetime" means that you need to apply a shader to this array. If you want to talk about physics of the pro
by goohle 5y ago
Spacetime is just 4D array: [x,y,z;t]. "Bending of spacetime" means that you need to apply a shader to this array.
If you want to talk about physics of the process, then you need to pick up a physical medium first, not an array of measurements.
- jcun4128 5y agoI don't get in many depictions they show this planet/ball over a grid that's deforming downwards. I can understand how another mass would want to "fall" into that but is it actually that shape (has up/down) or it some kind of sphere. I also believe with regard to mass clumping, gravity is strongest near the surface of the Earth vs. inside where you could say it's equal/0 except the oblique part.
- ben_w 5y agoThe rubber sheet analogy is criticised for this exact reason. Here’s a different visualisation that starts with what’s wrong with the rubber sheet: https://youtu.be/wrwgIjBUYVc https://youtu.be/wrwgIjBUYVc
- jcun4128 5y agoOh yeah I can see the 3D sinking inwards that's a neat video haven't seen that slicing idea before
- leephillips 5y agoThat’s the best visualization of gravitation I’ve ever seen. Well done. I recommend it to anyone who’s been misled by the ubiquitous rubber sheet picture.
- SavantIdiot 5y agoThat's a great video. 7:50 is the important twist for me, and 10:25 really drives it home. I'll never forget that video now and it explains so much. THere's still one "flaw" with this video: explaining that the grid "moves" is a little confusing. It doesn't move per-se, it .. evolves? ... over time. That's weird. I keep wanting to think the curves are static, but from t0->tn the grid pinches up. Yes, that's why they call it spacetime, but I have to stop and reset myself because how can the grid keep pinching up indefinitely but it doesn't it is just a concept. That is a stumbling block. 35 years after my last physics class...lol.
- pomian 5y agoThat's an amazing little video. thanks for posting. (Maybe that should go on to the main page, at some point)
- rdtsc 5y agoGreat video. Another one I like is "Why Gravity is NOT a Force" from Veritasium https://www.youtube.com/watch?v=XRr1kaXKBsU https://www.youtube.com/watch?v=XRr1kaXKBsU
- drran 5y agoIt uses gravity force to demonstrate that gravity force is not a force. ;-)
- akomtu 5y agoThat's clever. I'd suggest an improvement. When a sat has initial speed, show its small local reference frame, so we'd see that it always moves forward in its own reference frame, but the frame happens to be pulled to Earth.