4 ms·

Interesting, it should be theoretically possible to use gravitational lensing to view a past version of earth, no?

by victor9000 4y ago

beckingz 4y ago
You would probably need a telescope larger than earth to do this.
- Spare_account 4y ago
  Using interferometery of orbiting observatories (potentially on solar orbits, to leverage the entire diameter of the solar system), this is conceivably possible
  - tomjakubowski 4y ago
    Having just visited Mt. Wilson, and learning about CHARA, this idea sounds fantastic.
mortehu 4y ago
Is there anything we can do deliberately to use gravitational lensing other than aiming a telescope at a part of the sky where this is happening by random chance?
- lasc4r 4y ago
  Other than deliberately pointing a telescope at massive objects, I'd say no.
- ckw 4y ago
  Video discussing the use of the sun as a gravitational lens to image exoplanets: https://youtu.be/NQFqDKRAROI https://youtu.be/NQFqDKRAROI
holoduke 4y ago
Would there be fotons of walking dinosaur still floating around into our direction after making a complete u turn somewhere?
- gfodor 4y ago
  Milky Way core is approx 25k ly away so you’d see earth 50k years ago. Sorry no Dinos.
cvoss 4y ago
You would need a gravitational lens so powerful it not only bent light, but made the light perform a complete slingshot around it so that it would be aimed back at Earth. The nearest such object is the Milky Way's black hole, and there's no way we'd be able to resolve Earth in an image coming from a) that far away and b) that close to the galactic core where so much other stuff is in the way. But could a photon make such a journey? Yes. But you'd never be able to recognize it against everything else.
- cvoss 4y ago
  To correct myself, because I didn't actually bother to check first, there are actually black holes or probable black holes closer than the center of the galaxy. Like, a lot closer. [1] And we've seen a lensing effect from at least one of them. And moreover that one happens to be isolated from other material. [2] [1] https://en.m.wikipedia.org/wiki/List_of_nearest_known_black_holes https://en.m.wikipedia.org/wiki/List_of_nearest_known_black_... [2] https://en.m.wikipedia.org/wiki/OGLE-2011-BLG-0462 https://en.m.wikipedia.org/wiki/OGLE-2011-BLG-0462
- m463 4y ago
  wait until we launch the next telescope... er graviscope
- mgdlbp 4y ago
  Fermi problem: How many photons do? Have you or I ever seen one?

Interesting, it should be theoretically possible to use gravitational lensing to view a past version of earth, no?

beckingz 4y ago

You would probably need a telescope larger than earth to do this.

Spare_account 4y ago
Using interferometery of orbiting observatories (potentially on solar orbits, to leverage the entire diameter of the solar system), this is conceivably possible
- tomjakubowski 4y ago
  Having just visited Mt. Wilson, and learning about CHARA, this idea sounds fantastic.

mortehu 4y ago

Is there anything we can do deliberately to use gravitational lensing other than aiming a telescope at a part of the sky where this is happening by random chance?

lasc4r 4y ago
Other than deliberately pointing a telescope at massive objects, I'd say no.
ckw 4y ago
Video discussing the use of the sun as a gravitational lens to image exoplanets: https://youtu.be/NQFqDKRAROI https://youtu.be/NQFqDKRAROI

holoduke 4y ago

Would there be fotons of walking dinosaur still floating around into our direction after making a complete u turn somewhere?

gfodor 4y ago
Milky Way core is approx 25k ly away so you’d see earth 50k years ago. Sorry no Dinos.

cvoss 4y ago

You would need a gravitational lens so powerful it not only bent light, but made the light perform a complete slingshot around it so that it would be aimed back at Earth. The nearest such object is the Milky Way's black hole, and there's no way we'd be able to resolve Earth in an image coming from a) that far away and b) that close to the galactic core where so much other stuff is in the way. But could a photon make such a journey? Yes. But you'd never be able to recognize it against everything else.

cvoss 4y ago
To correct myself, because I didn't actually bother to check first, there are actually black holes or probable black holes closer than the center of the galaxy. Like, a lot closer. [1] And we've seen a lensing effect from at least one of them. And moreover that one happens to be isolated from other material. [2] [1] https://en.m.wikipedia.org/wiki/List_of_nearest_known_black_holes https://en.m.wikipedia.org/wiki/List_of_nearest_known_black_... [2] https://en.m.wikipedia.org/wiki/OGLE-2011-BLG-0462 https://en.m.wikipedia.org/wiki/OGLE-2011-BLG-0462
m463 4y ago
wait until we launch the next telescope... er graviscope
mgdlbp 4y ago
Fermi problem: How many photons do? Have you or I ever seen one?