• harmbugler@piefed.social
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    1 day ago

    You can already do this with the light bent around black holes, it’s just a bit hard to make out the image… make sure you wipe down your black hole with a damp cloth, you don’t want a smudgey black hole

  • Natanox@discuss.tchncs.de
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    2 days ago

    But only after 10 years. You couldn’t see anything that wasn’t visible from the viewpoint of the mirror beforehand, as from earth’s point of view the mirror isn’t there yet. And if you’re there anyway… you can just look at Earth with the craft that’s on the position of the mirror already.

    • Beacon@fedia.io
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      2 days ago

      That’s why we need to find a natural mirror somewhere already out there, so we can see into our past. Something like a planet made of pure mercury, or an arrangement of blackholes doing gravitational lensing that bends our light back to us, or whatever. We’d also need instruments vastly superior than what we currently have in order to get any useful information out of seeing our own light bounced back to us from so far away

      … But still! the idea that it’s at least hypothetically possible to actually see our own past is very exciting!

      • Klear@quokk.au
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        2 days ago

        Just look in any mirror. What you see is also you in the past.

        • Optional@lemmy.world
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          2 days ago

          “‘That’s a picture of me when I was younger.’ Yeah, no shit. Every picture of you is a picture of you when you were younger.”

          -Mitch Hedberg

          • Beacon@fedia.io
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            2 days ago

            He didn’t curse in that line. In fact he didn’t curse much generally. I don’t have any objection to curse words, it just doesn’t sound like his voice when you add curse words in.

            Fuck shit ass titties. I just had to get that out after talking about not cursing

        • Sprawl@lemmy.world
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          1 day ago

          True true. Heck it takes some 100-150ms for your brain to register what your eyes have seen.

      • kernelle@lemmy.dbzer0.com
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        2 days ago

        I’m assuming the inverse square law would hinder us from seeing anything useful. But now I’m imagining scientists being ecstatic about discovering a foreign signal, only to realise its us from the past

        • MotoAsh@piefed.social
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          2 days ago

          That’s highly unlikely basically because of the inverse square law. Even tightly focused beams dissipate quite effectively over light-hours, let alone light years. We’d be lucky to catch a single photon from our past selves over any significant distance.

          For reference, look up how weak the signal is even just coming back from the moon when people try to hit the retroreflectors with lasers. Or how crazy weak the signals are when they reach Voyager.

      • ameancow@lemmy.world
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        1 day ago

        … But still! the idea that it’s at least hypothetically possible to actually see our own past is very exciting!

        We… we have tools for seeing our past. We have extensive records of imagery from as far back as we have orbital satellites. You can go on Google Earth right now and look at older maps.

        I mean, I get why it would be cool to see a reflection from the past, but literally every reflection you see is from the past. At a certain distance from your reflective or distorting surface, you’re going to need major image processing to make out a clear image of the planet, so again, at that point it’s far easier to just look at recorded images or videos.

        There is a much cooler idea though that you can exploit from this principle: you can use a star or other dense object in space to work like a light-lens, we could build this now but it would be a very expensive and long-term project, because we would need to send a series probes out past the distance that Voyager 1 has already traveled over 40 years. We would also need to know ahead of time what our target is so we place the probes in the right place, placing the sun between the probes and the target at just the right distance.

        If you take the distorted light from around the edges of the Sun and reconstruct it, you can theoretically see details of continents and other surface features of Earth-sized planets in entire other solar systems, which would be fantastic.

        • Beacon@fedia.io
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          1 day ago

          it’s far easier to just look at recorded images or videos.

          You’re missing the idea of why this is cool. Recorded images only go back a couple hundred years

      • Natanox@discuss.tchncs.de
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        2 days ago

        No, the light would be reflected as soon as the mirror is set up. If the mirror is set up 10 lightyears away it would take 10 years for you to see it and whatever it reflects. There already is light on the way to the position of the mirror before you set it up.

  • this@sh.itjust.works
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    1 day ago

    If you did this quickly with a warp drive or whatever, you would still need at least ten years to see the results, so you could only see as far back as when you put the mirror up at the most.

    • EddoWagt@feddit.nl
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      20 hours ago

      No, you can see 20 years into the past, but only in 10 years. If you managed to will it into existence now, the light that left us 10 years ago would arrive at the mirror now and start heading back. That light would hit earth 10 years from now, so in 2035 we’d be able to see 2015

  • 🇰 🌀 🇱 🇦 🇳 🇦 🇰 🇮 @pawb.social
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    1 day ago

    It’d actually be cool as fuck if we could make some kind of Paycheck-style time machine that lets you see into the past by simply looking at light reflected off other celestial objects.

    It could theoretically work looking backwards, but not forwards as it was used in the film. Of course, it’d have to have insane resolution for it to be like a video of what happened on the planet and not just a dot of light.

    • blackbrook@mander.xyz
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      1 day ago

      Isn’t the butt end, the end you normally look through? I’d think the end facing the stars would be the front end.

  • Steve Dice@sh.itjust.works
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    1 day ago

    Yeah, but it’d take us strictly longer than N years to place a mirror N light years away form Earth, so kinda useless.

    • Sprawl@lemmy.world
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      1 day ago

      We just need to point our telescopes towards the phantom zone where Zod and his buddies can reflect the light back.

  • Zwrt@lemmy.sdf.org
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    1 day ago

    Big brother called, you weren’t supposed to leak this hack.

    If only they did work into the future then they could have stopped you from spilling the beans.

  • brvslvrnst@lemmy.ml
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    2 days ago

    It would be neat to record the mirror as it was going.

    Ignoring physics of moving a mirror near the SoL, having a recording of it would both be cool to watch and would help confirm on a macro level the effects of speed-related dilation.

    • Echo Dot@feddit.uk
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      1 day ago

      No that’s not how light works. It’s not 20 years either direction otherwise you could use your bathroom mirror to see into the future

    • Sprawl@lemmy.world
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      1 day ago

      No you always see into the past.

      Light cannot travel back in time. The reflection you’d see in the mirror is the light that left the Earth 20 years ago.

      • Bennyboybumberchums@lemmy.world
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        1 day ago

        The mirror always looks back… (insert annoying spooky laugh)

        But, just to be less of a Halloween spookster. The mirror is placed in a rather exotic location in space, and between the mirror and the Earth is… wait for it… youre going to hate this lol… a naturally occurring closed timelike curve! See, I told you youd hate it lol.