• mozz@mbin.grits.dev
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    5 months ago

    You’re confused, sir. Light from the sun is collimated, yes, i.e. parallel rays. The correct equation if you’re going to apply the inverse square law is:

    E = 850 watts / 149,597,971 km^2 * 149,597,871 km^2 = 849.998864 watts

    Same reason a signal mirror can reflect a flash as bright as the sun even miles away off a surface a few inches square.

    You can believe or not; I’ve explained it as clearly as I know how.

    • TropicalDingdong@lemmy.world
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      5 months ago

      149,597,971

      Where are you getting this number from? The number you need to be using is the distance from the earth to the ISS, 408,000 meters.

      Second, your formulation of the inverse square law is incorrect, in that you are missing the 4pi component, but in the grand scheme of distances we’re looking at, its negligible. It also looks like you may have gotten the order of operations wrong.

      Third

      149,597,971 km^2 * 149,597,871 km^2

      The hell even is it that you think you are representing by these numbers? What is it you think you are saying?

      fourth

      You can believe or not; I’ve explained it as clearly as I know how.

      I can provide sources for all my claims, and I’m pretty sure I got all my math correct, within a ROM. I can’t say the same for your work.

      • mozz@mbin.grits.dev
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        5 months ago

        Where are you getting this number from?

        I’m gonna leave the source of that and the other number and where the pi went as an exercise for the reader

          • mozz@mbin.grits.dev
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            5 months ago

            Will you bet me money on how signal mirrors work and how bright the flash is at a certain distance from the mirror?

            • TropicalDingdong@lemmy.world
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              5 months ago

              I will take a bet from you that the energy arriving at the ISS from a laser pointer you or I could purchase off Amazon, so consumer grade, is more than the energy that would arrive at the ISS from a concave mirror that would be used at a solar generating station.

              • mozz@mbin.grits.dev
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                5 months ago

                A perfectly flat mirror, exactly like one of the ones in the OP generating station picture. Both are aimed perfectly on target, and the mirror is reflecting light from the sun on a sunny day. With those caveats I’ll bet $1,000. I’m happy with any university physicist or physics professor to be the judge, or Randall Munroe, or make a proposal of some other person if neither of those are acceptable to you. A lower amount of money is also fine if you’re not comfortable with $1,000.

                • TropicalDingdong@lemmy.world
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                  5 months ago

                  I think the mirror should be a standard one from the Ivanpah Solar power facility. Wikipedia puts them at 7 meters in area. Wikipedia also puts it at 7.4 kWh/m2/day. I think those would be acceptable parameters for you? I think this fits in with the spirit of the bet because these would be the specific parameters taken from the mirrors mentioned in the meme.

                  Do you have any suggestions for me on parameters to constrain my shopping on Amazon for laser parameters? I said a laser I could purchase on Amazon, so I’m ok with sticking with them as a source. I can buy some pretty damn beefy lasers off Amazon. For example, I can buy a 2000 watt laser on prime right now. Do you want constraints here?

                  Also, $1000 is out of my price range. I can afford to lose $100. Are you ok with that?

                  • mozz@mbin.grits.dev
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                    5 months ago

                    Well but the actual mirrors would not work at all because of any number of reasons (among other reasons they can’t track fast enough or precisely enough to actually hit a satellite, and they’re going to have little imperfections in their flatness which will distort the reflected beam away from what the laws of optics say would happen for an idealized situation). The whole actually-shooting-down-satellites thing is clearly a joke; my point was more disagreeing with your description of how the laws work in the idealized situation.

                    Hmm… I am confident that optically, an idealized flat mirror will reflect a patch of sunbeam that’s more collimated than any human-produced laser at any price. I’m less sure about the actual Ivanpah mirrors but I would guess that they are flat enough to produce a beam that’s more collimated than a standard consumer laser. The thing is that that’s more or less impossible to test… we can ask a physicist about the physical laws, but my guess is that they would be as clueless as I am about how precisely flat the mirrors actually are and of course there’s a lot of wiggle room in how fancy a laser we want to say you can get.

                    We could ask one of those Youtubers like the ones I linked to if they want to fly a helicopter into the beam from one mirror at a great distance and do measurements of how much the beam had attenuated in practice, but that seems like a great setup to a “what could go wrong” disaster video in the making…