The making of telescopes is constantly improving, to the point where, in a few decades or so, we'll be able to build really super-duper big ones. The making of mirrors is also presumably improving, likewise.
Once these two technologies have advanced far enough, what we should obviously do is to put a really big mirror somewhere out around the orbit of Jupiter. We might want to put a few, in fact.
Then, when your cat goes missing or there's an armed robbery, all you need to do is point the Really Big Telescope at the Really Big Mirror, and you'll be able to watch what actually happened about an hour and half ago. That should allow you to either see where your cat went (assuming you want it back) or watch the armed robbers arriving at the scene of the crime.-- MaxwellBuchanan, Nov 19 2018 2.6 seconds to the moon & back https://www.google....eid=chrome&ie=UTF-8and we already have some mirrors there [Skewed, Nov 24 2018] 70-104 minutes to Jupiter & back https://www.google.....0....0.iz7R0JtM6REthat's a reasonably workable lead-time [Skewed, Nov 24 2018] why you can't see anything small on the moon even with the Hubble telescope https://www.google.....0....0.KaEVeVNRQ8git's all about resolution [Skewed, Nov 24 2018] Lagrangian point https://en.wikipedi...ki/Lagrangian_pointBasic orbital mechanics. [8th of 7, Nov 24 2018] Stubby Hubbles https://en.wikipedi...pe_donation_to_NASA [bs0u0155, Nov 28 2018] Synthetic Aperture https://en.wikipedi.../Aperture_synthesis [bs0u0155, Nov 28 2018] Wouldn't a cloudy day require some extra strength penetration rays? I was going to post an idea for chromium plating the moon, but I doubt that even the Chinese will have much money left after they've built this ridiculous mirror. Damn you Max! +-- xenzag, Nov 19 2018 I was rather counting on most cats and criminals staying home in cloudy weather.-- MaxwellBuchanan, Nov 19 2018 so I've often wondered if in some galactopedia of some advanced race with sufficiently advanced interfering telescopes there's footage of anything important that may have ever happened on Earth-- theircompetitor, Nov 19 2018 Well, if anything important happens, we may find out.-- MaxwellBuchanan, Nov 19 2018 There is of course truth in the idea as verified by my favourite genius De Selby who was able to prove by total logic that an array of mirrors could show time reaching backwards.
This is an extract of a page on the great man from Irishphilosophy: "Another theory of de Selby’s was that mirrors held the secret to eternity. His starting point was the reflection that, “[i]f a man stands before a mirror and sees in it his reflection, what he sees is not a true reproduction of himself but a picture of himself when he was a younger man” (O’Brien, TTP.5). This is due to light travelling at a fixed speed – thus the image must be of a (very slightly) younger man. de Selby claimed that by utilising this insight and creating a huge array of parallel mirrors, he succeeded in seeing his own face as a boy of twelve."-- xenzag, Nov 20 2018 Thanks for mentioning de Selby's insight. Now I'll have an explanation for my wife when I see a younger man in the mirror than what she describes about me! Clearly she isn't using a mirror. I'll point her in the general direction of Jupiter (as long as there is not planetary alignment)-- tumblewit, Nov 20 2018 Some years ago, I thought about posting a more ambitious version of this for the purposes of historical research. I think The Big Hairy Entropy Monster got in the way.-- pertinax, Nov 20 2018 //you're better off with a shortlist of cats// Well, that won't be a problem. The odds of any one person losing more than a few cats at one time are quite small.-- MaxwellBuchanan, Nov 20 2018 However, those odds are non-zero, and depending on locality it is not impossible for all the cats to disappear nearly simultaneously (depending on how quickly it's possible to reload)
// advanced race with sufficiently advanced interfering telescopes //
Widely known to exist.
// anything important that may have ever happened on Earth //
Widely known not to exist.
You will need several telescopes, placed at widely spaced points around the orbit, due to your planet's rotation and inclination. Even then, spotting a straying cat during the Antarctic winter may be challenging (as there are ample opportunities for dropping the corpse into a crevasse, or stuffing it under a snowdrift).-- 8th of 7, Nov 20 2018 Seems like the distant mirror ought to be concave so that it is actually part of an enormous telescope. I'm a little rusty on the optics of reflecting telescopes to know if that is feasible without having to also have other incredibly huge mirrors that have to move around to select the target of the telescope.-- scad mientist, Nov 20 2018 The originality of this idea trumps the, uh... technical obstacles. [+]-- doctorremulac3, Nov 23 2018 So, you're saying there are technical obstacles?-- MaxwellBuchanan, Nov 23 2018 Nothing a big government grant couldn't solve. Or at least create a feasibility study for. Or at least get a tax increase through Congress to fund.-- doctorremulac3, Nov 23 2018 That sounds great! I was planning to fund this one myself, but if you Americans are willing to stump up the cash, that'd mean I can afford to re-glaze the north-east pineapple house in time for Christmas. Magic.-- MaxwellBuchanan, Nov 23 2018 No prob, just write a nice note to: "U.S. Government, Department of big money giveaway programs, Washington, D.C."
Give 'em 6 to 8 weeks, they get pretty busy this time of year.-- doctorremulac3, Nov 23 2018 This idea will work extremely well once we have invented a way of sending the signal to point the mirror to Jupiter at a speed greater than the speed of the light emited from the cat/armed robbers.-- bhumphrys, Nov 24 2018 Ah, but that's the cunning part - you see, it's a _really big_ mirror.
As far as I can tell, the only fundamental problem will be that law-enforcement officers will waste hours arguing about why the crime scene is reversed left-to-right but not top-to- bottom.-- MaxwellBuchanan, Nov 24 2018 It's a pity the moon isn't really far enough away, as we've already got mirrors up there.-- Skewed, Nov 24 2018 As long as you're aware of the crime in time to catch the return image (& it occurred on the Jupiter facing side of the planet of course) this actually sounds workable (if only for literary purposes)..
If you've adequate RBM & RBM-delivery technology (presumably among [docs] //technical obstacles// along with resolution issues) of course.
Where do we put the other 5 mirrors for complete global coverage?-- Skewed, Nov 24 2018 At the Lagrangian points, of course. <link>-- 8th of 7, Nov 24 2018 Is travel time there & back sufficient to be persaudably useful for the purpose envisioned?
L5 & L4 look (like they might be) good? but L3 is obscured by the sun yes? while L1 & L2 don't look to be much further off than the moon?-- Skewed, Nov 24 2018 There is a small problem of the atmosphere and clouds in the way...-- RayfordSteele, Nov 25 2018 //the Lagrangian points
Has anyone contacted the Lagrangian government? They could get a bit tetchy.
It might be best to examine the mirrors on Phobos and Deimos, to see how effective they are. How many Tripods get returned to their drivers,etc
I tole them Martians, get a bent coat hanger and the hatch just pops out, but do they listen?-- not_morrison_rm, Nov 25 2018 No, but it's not their fault ... it's the thin atmosphere, sound doesn't propagate well.-- 8th of 7, Nov 25 2018 //you can't see anything smallish on the moon even with the Hubble telescope,//
pffft. Don't believe any of that. NASA were given a couple of extra Hubbles that the NRO had sitting around <link>. One Hubble and they're right about the resolution, but the good thing about the moon is that it's super easy to image in terms of light and stability. So, a little optical interferometry <link> and synthetic aperture stuff and the landing sites would be pretty trivial to image with 3.-- bs0u0155, Nov 28 2018 ^ As the moon is monochrome they only have to use b&w film, a major cost saver.-- not_morrison_rm, Nov 28 2018 random, halfbakery