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> 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 fa

> 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.

Dalewyn 2y ago
>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.
- tbrownaw 2y ago
  "Normal" lenses bend light more strongly farther out towards the edges. Gravitational lensing is shaped differently.
  - Dalewyn 2y ago
    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.
    - oneshtein 2y ago
      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.
      - codesnik 2y ago
        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?
        oneshtein 2y ago
        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.
        ithkuil 2y ago
        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.
        oneshtein 2y ago
        LIGO/Virgo/KAGRA found that speed of light in vacuum is affected by gravitational waves. This is verified experimentally to very high precision (1.2E-20m). If merge of neutron stars 200 megaparsec away can affect propagation of light here, on Earth, then why it cannot affect it near to the star?
    - s1artibartfast 2y ago
      Obviously, you are correct. Gravity bends space, it doesn't bend vectors in space.
freeqaz 2y ago
But if the light is "warping" around the object then would you be able to grab the light from either side by intercepting it there? If you are at the X AU required for lending, but you sit at X/2 AU with some slight offset, you would be in the path of the light that would be traveling to X AU eventually. I understand if what I'm trying to describe is impossible, I just don't fully understand why. (Is it out of focus? Is the sun too big/bright?)
- HellzStormer 2y ago
  I'm no expert here. You mention "either side" as if the light came from both the left and the right. But I think the light would be coming along a circle all around the sun depending on exact position. So the trick here is that if you are at the focus point, you get all that light in a small area "for free". But if you try to catch the light on the way, you now need to catch eveywhere in a whole massive circle, which is basically impossible, so you only catch a minuscule amount of the light. And then have to deal with interferometry.
- cyberax 2y ago
  > But if the light is "warping" around the object then would you be able to grab the light from either side by intercepting it there? Certainly. But it won't be any more focused at that location. There's no real advantage compared to just building a regular phased antenna array.

Dalewyn 2y ago

>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.

tbrownaw 2y ago
"Normal" lenses bend light more strongly farther out towards the edges. Gravitational lensing is shaped differently.
- Dalewyn 2y ago
  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.
  - oneshtein 2y ago
    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.
    - codesnik 2y ago
      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?
      - oneshtein 2y ago
        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.
        ithkuil 2y ago
        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.
        oneshtein 2y ago
        LIGO/Virgo/KAGRA found that speed of light in vacuum is affected by gravitational waves. This is verified experimentally to very high precision (1.2E-20m). If merge of neutron stars 200 megaparsec away can affect propagation of light here, on Earth, then why it cannot affect it near to the star?
  - s1artibartfast 2y ago
    Obviously, you are correct. Gravity bends space, it doesn't bend vectors in space.

freeqaz 2y ago

But if the light is "warping" around the object then would you be able to grab the light from either side by intercepting it there? If you are at the X AU required for lending, but you sit at X/2 AU with some slight offset, you would be in the path of the light that would be traveling to X AU eventually. I understand if what I'm trying to describe is impossible, I just don't fully understand why. (Is it out of focus? Is the sun too big/bright?)

HellzStormer 2y ago
I'm no expert here. You mention "either side" as if the light came from both the left and the right. But I think the light would be coming along a circle all around the sun depending on exact position. So the trick here is that if you are at the focus point, you get all that light in a small area "for free". But if you try to catch the light on the way, you now need to catch eveywhere in a whole massive circle, which is basically impossible, so you only catch a minuscule amount of the light. And then have to deal with interferometry.
cyberax 2y ago
> But if the light is "warping" around the object then would you be able to grab the light from either side by intercepting it there? Certainly. But it won't be any more focused at that location. There's no real advantage compared to just building a regular phased antenna array.