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Two galaxies aligned in a way where their gravity acts as a compound lens

(phys.org)
268 points wglb | 2 comments | 16 Nov 24 16:48 UTC | HN request time: 0.653s | source
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bparsons ◴[16 Nov 24 20:12 UTC] No.42158887[source]▶
If the lens curved light back toward us, could we see earth several million years ago?
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1. wizzwizz4 ◴[16 Nov 24 20:17 UTC] No.42158948[source]▶
Technically? But the image would be very very very small, so we'd need a detector bigger than the solar system (guesstimate) to see it. That's to see it: I can't imagine what it would take to resolve the image. The tricks in this paper are a start.
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2. westurner ◴[16 Nov 24 20:50 UTC] No.42159195[source]▶
To zoom into a reflection on a lens or a water droplet?

From "Hear the sounds of Earth's magnetic field from 41,000 years ago" (2024) https://news.ycombinator.com/item?id=42010159 :

> [ Redshift, Doppler effect, ]

> to recall Earth's magnetic field from 41,000 years ago with such a method would presumably require a reflection (41,000/2 = 20,500) light years away

To see Earth in a reflection, though

Age of the Earth: https://en.wikipedia.org/wiki/Age_of_Earth :

> 4.54 × 10^9 years ± 1%

"J1721+8842: The first Einstein zig-zag lens" (2024) https://arxiv.org/abs/2411.04177v1

What is the distance to the centroid of the (possibly vortical ?) lens effect from Earth in light years?

/? J1721+8842 distance from Earth in light years

- https://www.iflscience.com/first-known-double-gravitational-... :

> The first lens is relatively close to the source, with a distance estimated at 10.2 billion light-years. What happens is that the quasar’s light is magnified and multiplied by this massive galaxy. Two of the images are deflected in the opposite direction as they reach the second lens, another massive galaxy. The path of the light is a zig-zag between the quasar, the first lens, and then the second one, which is just 2.3 billion light-years away

So, given a simplistic model with no relative motion between earth and the presumed constant location lens:

  Earth formation: 4.54b years ago
  2.3b * 2 = 4.6b years ago 
  10.2b * 2 = 20.4b years ago
Does it matter that our models of the solar systems typically omit that the sun is traveling through the universe (with the planets swirling now coplanarly and trailing behind), and would the relative motion of a black hole at the edge of our solar system change the paths between here and a distant reflector over time?

"The helical model - our solar system is a vortex" https://youtube.com/watch?v=0jHsq36_NTU