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Yes! Problem being that if we launched the mirror a light-year away, it would take more than a year to get there, and once we got the telescope set up, it woul
by klyrs 4y ago
Yes! Problem being that if we launched the mirror a light-year away, it would take more than a year to get there, and once we got the telescope set up, it would only show us a year in the (relatively speaking) past. Send it a million light years away, it would take more than a million years to get there, and our million-year-distant descendents would only see a million years in their past. So we wouldn't see into our past... it would be cheaper to just launch a camera into space with a long buffer of tape.
However, black holes are known to curve space-time and I've often wondered if we could find a sequence of black holes in a configuration that would bend the earth's light back on itself... theory being that if we had good enough resolution we might actually be able to see our deep past. I have no optimism that we could resolve organisms though -- just finding the sun, and seeing what it looked like in the past would be an incredible feat.
- yreg 4y agoWe should pop up a mirror facing away from Earth as a service for anyone who wants to look at their past. Hopefully someone else did that for us, just need to find it. It's a common courtesy.
- klyrs 4y agoBe the change you want to see in the galaxy...
- gfodor 4y agoThis is kind of a fascinating idea - wouldn’t it be kind of an amazing “public service” to just deploy a large reflective perfect sphere into space at the galactic restful reference frame?
- macintux 4y agoUpdate: April Fools joke that won’t die. Mea culpa. Reminds me of the Dr. Who episodes recovered via Arecibo. https://dailypop.wordpress.com/2011/11/01/lost-doctor-who-episodes-found-in-deep-space/ https://dailypop.wordpress.com/2011/11/01/lost-doctor-who-ep...
- yreg 4y agoDid they actually recover any lost episode this way? Do we know which one(s)?
- macintux 4y agoNow that I look more closely it was an April Fools joke. Whoops. See the small note at the end: > I just realized that this story was hosted on a blogger’s site, not the Beeb… and it was loaded on Wednesday, 1 April 2009… well done. You got me over two years later.
- yreg 4y agoI thought it looked suspicious, but didn't notice it's a joke either. And there are multiple articles retelling it.
- vikingerik 4y agoStated more succinctly: Any mirror we launch couldn't catch up with any light emitted from before the mirror launched. So we couldn't see our past that way. We could do it only with a reflector/bender that already existed in the light cone future from when the light was emitted.
- 7373737373 4y agoI'm not sure where I've seen this described, but apparently a single black hole already reflects light back toward the observer, through a series of concentric rings, where each inner ring reflects light that has gone one more time around the black hole Edit: https://www.quantamagazine.org/black-holes-ring-of-light-could-encrypt-its-inner-secrets-20220908/ https://www.quantamagazine.org/black-holes-ring-of-light-cou... > Photons that make a single U-turn around a black hole and then zip toward Earth would appear to us as a single ring of light. Photons that make two U-turns around the hole appear as a fainter, thinner subring within the first ring. And photons that make three U-turns appear as a subring within that subring, and so on, creating nested rings, each fainter and thinner than the last. > Light from the inner subrings has made more orbits and was therefore captured before the light from outer subrings, resulting in a series of time-delayed snapshots of the surrounding universe. “Together, the set of subrings are akin to the frames of a movie, capturing the history of the visible universe as seen from the black hole,”
- klyrs 4y agoIt does... but I'm guessing those rings of navelgazing, as it were, would be infinitesimally thin. Further out, there is less distortion and perhaps a hope of figuring out what one is looking at. Edit: a ring??? Mind blown. I guess it makes sense, the light doesn't have a preferred direction to travel around the hole... still, that's wild. It's like how photoreflectors throw light back where they came, but instead of internal reflections of a sphere... yup, mind blown
- swsdsailor 4y agoThis is an absolutely incredible notion! Given the vastness of space, I wonder if it might happen!
- sjducb 4y agoYou might get better resolution than you think. Using the sun as a gravitational lens you could image the exoplanets at alpha centuri with meter resolution. If you're using a black hole as the lens then you might be able to image organisms at sub millimetre resolution from thousands of light years away.