A solar gravitational lens will be humanity's most powerful telescope (2022)

Is there anything stopping you from putting 2+ satellites out "closer" but in the path of the lensed light, capturing the light simultaneously, and then resolving the image via async computation later? I think this is called interferometry and I know it's hard because you need _very_ precise timing, but I'm curious if that would be possible or not. (Maybe you can get the timing in sync with atomic clocks, or by sending a laser to both from a central point that lets them keep time with some very tight tolerance?)

Weird idea but I wonder if there are ways to take this from "crazy tech" to "hard tech".

> Is there anything stopping you from putting 2+ satellites out "closer" but in the path of the lensed light

The Sun. Literally.

Satellites have to be that far for the Einstein ring to be bigger than the apparent size of the solar disk.

Edit: to make it a bit more clear, the gravitational lens does not quite behave like a normal lens. Instead, you see the light from _behind_ the object. So if you're too close to the lensing object so that the Einstein ring is not larger than it, you'll just see a part of the object to be a bit more bright.

Also, the gravitational lens does not actually _focus_ the image, it distorts it into a band around the lensing object.

>to make it a bit more clear, the gravitational lens does not quite behave like a normal lens. Instead, you see the light from _behind_ the object.

Or to put it another way: A gravity lens bends space so that the light from behind an object curves around it while travelling straight.

"Normal" lenses bend light more strongly farther out towards the edges. Gravitational lensing is shaped differently.

The point is you aren't bending the light, no the light is travelling straight.

You are bending the dimension, the light travels straight through a bent dimension thus coming out curved.

I think that's mindblowing.

No, light doesn't travel in straight lines.

Stronger gravity around massive objects causes slow down of the part of a light wave closer to object, compared to outer part.

This difference in speed, caused by _interaction_ between the photon and gravitational field of the body, results in the bending of the light's trajectory.

Bending of spacetime is just a simplification of this process to model that easier.

from what I understand, slowing down would be true for a non-massless particle, but speed of light in vacuum is still the same around massive objects. What changes is the frequency of the light in this particular direction, and that "turns" it, probably because of self-diffraction?

Parts of photon cannot have different frequencies than whole photon. Both inner and outer parts of photon will make exact same number of fluctuations for the same period of time, but inner part will travel slightly smaller distance.

It's the same effect as in reflections, except that speed difference between air and solid objects is much much bigger, which results in sharp turning radius.

The speed of light is constant as measured from any observer. This has been verified experimentally to a very high precision and motivated the development of special and general relativity.

Otoh there is no requirement for a wave front to have the same frequency as when it started. A gradient in the gravitational field can cause a gradient in the gravitational redshift and thus "parts of photon" can very well have slightly different frequencies. If you recombine the paths and have the photon to interfere with itself, the interference pattern will capture the shape of such a wave function as affected by the distortion in the gravitational field.

IIRC this is the "standard" way of thinking about what's going on although marrying quantum mechanics and general relativity is still a work in progress.

If you buy into another theory that involves a variable speed of light, I'd love to hear more about what exact theory are you talking about since it seems to me that the burden of proof is on who makes the most extraordinary claims.