h a l f b a k e r yNaturally, seismology provides the answer.
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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.
2.6 seconds to the moon & back
https://www.google....eid=chrome&ie=UTF-8
and we already have some mirrors there [Skewed, Nov 24 2018]
70-104 minutes to Jupiter & back
https://www.google.....0....0.iz7R0JtM6RE
that'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.KaEVeVNRQ8g
it's all about resolution [Skewed, Nov 24 2018]
Lagrangian point
https://en.wikipedi...ki/Lagrangian_point
Basic 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]
[link]
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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!
+ |
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I was rather counting on most cats and criminals staying home
in cloudy weather. |
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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 |
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Well, if anything important happens, we may find out. |
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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. |
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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." |
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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) |
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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. |
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//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. |
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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) |
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// advanced race with sufficiently advanced interfering telescopes // |
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// anything important that may have ever happened on Earth // |
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Widely known not to exist. |
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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). |
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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. |
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The originality of this idea trumps the, uh... technical
obstacles. [+] |
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So, you're saying there are technical obstacles? |
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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. |
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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. |
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No prob, just write a nice note to: "U.S. Government,
Department of big money giveaway programs, Washington,
D.C." |
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Give 'em 6 to 8 weeks, they get pretty busy this time of
year. |
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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. |
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Ah, but that's the cunning part - you see, it's a _really big_
mirror. |
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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. |
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It's a pity the moon isn't really far enough away, as we've
already got mirrors up there. |
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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).. |
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If you've adequate RBM & RBM-delivery
technology (presumably among [docs] //technical
obstacles// along with resolution issues) of course. |
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Where do we put the other 5 mirrors for complete global
coverage? |
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At the Lagrangian points, of course. <link> |
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Is travel time there & back sufficient to be persaudably
useful for the purpose envisioned? |
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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? |
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There is a small problem of the atmosphere and
clouds in the way... |
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Has anyone contacted the Lagrangian government? They
could get a bit tetchy. |
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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 |
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I tole them Martians, get a bent coat hanger and the
hatch just pops out, but do they listen? |
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No, but it's not their fault ... it's the thin atmosphere, sound doesn't propagate well. |
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//you can't see anything smallish on the moon even with
the
Hubble telescope,// |
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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. |
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^ As the moon is monochrome they only have to use b&w film, a major cost saver. |
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