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Can we see an object twice at the exact same time at far distances? in c/askphysics
[–] [email protected] 1 points 3 hours ago

I wonder if such a situation could occur if we were in some huge medium where Cherenkov radiation could occur

Can we see an object twice at the exact same time at far distances? in c/askphysics
[–] [email protected] 2 points 16 hours ago

Hmmmm, I guess that the premise was probably wrong then, since the object necessarily has to have mass and travel slower than c (I mean, a massless object would be constrained the by c anyways). The gravitational lensing is a good addition! I have no idea how I forgot, but I remember a hs physics class where this came up for new telescope images

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Can we see an object twice at the exact same time at far distances? (discuss.tchncs.de)
 

If we look into a far off distance at an object travelling towards Earth, shouldn't we be able to see both the light from the object at some time t plus the light at some later time (t + delta t)?

Let's also assume that the object is traveling fast enough that it is discernable. This point might be moot, since I'm not sure if such a situation is possible. I know that Rayleigh's criterion could give us a lower bound for how far the images of the object has to be, though I'm not sure how complicated it would be to throw redshift into the mix.

This seems like one of those "Whoa this feels see weird causally but it's just a natural consequence of things we've observed thus has little repercussions as to what limitations physicists actually work around." Actually, I could see perhaps long exposure photos (or the telescope equivalent, if it exists) could run into issues.

My mnemonic for remembering trig values in c/[email protected]
[–] [email protected] 1 points 18 hours ago

I always just used my left hand with the thumb and pinky as the y and x axes respectively, then the in-between fingers just help me visualize which "point" is higher (we only have two options to choose from if they're not equal anyways)

I'm so confused by this simple PDE. Any ELI5 explanations? in c/[email protected]
[–] [email protected] 2 points 18 hours ago

Absolutely agree, lowk a programmer must've done it else I don't think I've met a mathmematician (or maybe, not crazy enough ones) that ever preferred redefining variables (esp in pedagogical material!!!!)

I'm so confused by this simple PDE. Any ELI5 explanations? in c/[email protected]
[–] [email protected] 1 points 18 hours ago* (last edited 18 hours ago)

What do you want to learn PDEs for? It's not my strong point, but I've heard high praise for Partial Differential Equations by Stanley J. Farlow. I found it useful in my undergrad, else I think I could have died in analytical mechanics