1441: Turnabout

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1441: Turnabout

Postby Chris Dude70 » Fri Oct 31, 2014 5:54 am UTC

Image

Title Text: Whenever I miss a shot with a sci-fi weapon, I say 'Apollo retroreflector' really fast, just in case.


That shot came from, the moon!
No?
>.>
<.<

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Re: 1441: Turnabout

Postby bachaddict » Fri Oct 31, 2014 6:32 am UTC

When I read the title I thought 'Roundabout' and expected something like Traffic Lights.
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Re: 1441: Turnabout

Postby rhomboidal » Fri Oct 31, 2014 6:42 am UTC

I'll bet astrophysicists mumble "pew pew pew pew" every time they test the retroreflectors.

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That's no moon!

Postby Eternal Density » Fri Oct 31, 2014 7:05 am UTC

I am okay with this.
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Re: 1441: Turnabout

Postby Pfhorrest » Fri Oct 31, 2014 7:38 am UTC

It's a fair play.
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Re: 1441: Turnabout

Postby Sandor » Fri Oct 31, 2014 8:20 am UTC

The lightspeed round trip time to the moon and back is about 2.6 seconds. I was wondering if the two of them had time to say what they say.

From my count, the pair say 13 syllables in total in those 2.6 seconds, or 5 syllables/second, or 300 syllables/minute. From what I can gather, 300 syllables/minute is a fast talking rate (for a speech), so it's just about feasible.

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Re: 1441: Turnabout

Postby obfpen » Fri Oct 31, 2014 9:30 am UTC

Sandor wrote:The lightspeed round trip time to the moon and back is about 2.6 seconds. I was wondering if the two of them had time to say what they say.

Since they're using sci-fi weapons, who's to say they're on Earth*? Or using weapons that move at the speed of light? (Everyone knows you can jump out of the path of a phaser beam because they travel so slowly.)

* They're not called retroreflectors because they reflect light back to Earth, but because they're from the 60s and 70s. Ask a hipster.

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Re: 1441: Turnabout

Postby da Doctah » Fri Oct 31, 2014 9:56 am UTC

bachaddict wrote:When I read the title I thought 'Roundabout' and expected something like Traffic Lights.


I correctly read "Turnabout" and expected a reference to Thorne Smith.

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Re: 1441: Turnabout

Postby Klear » Fri Oct 31, 2014 10:02 am UTC

Works even better with a Portal Gun.

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Re: 1441: Turnabout

Postby schapel » Fri Oct 31, 2014 11:28 am UTC

rhomboidal wrote:I'll bet astrophysicists mumble "pew pew pew pew" every time they test the retroreflectors.

That and "I'm a-firin' ma lazar!"

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Re: 1441: Turnabout

Postby PinkShinyRose » Fri Oct 31, 2014 12:40 pm UTC

Klear wrote:Works even better with a Portal Gun.

Wait, can you fire portals through portals?

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Re: 1441: Turnabout

Postby mathmannix » Fri Oct 31, 2014 1:21 pm UTC

obfpen wrote:
Sandor wrote:The lightspeed round trip time to the moon and back is about 2.6 seconds. I was wondering if the two of them had time to say what they say.

Since they're using sci-fi weapons, who's to say they're on Earth?

That would be the person in the comic who fired the shot using them, when he said "Apollo". (If they're standing anywhere else than earth*, it would probably take much longer than 2.6 seconds to reflect light off earth's moon.)

* - or earth orbit (which would be about the same) or lunar orbit (which would be much less)
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Re: 1441: Turnabout

Postby cellocgw » Fri Oct 31, 2014 1:52 pm UTC

There's an ancient SF short story (my guess is 1950s) in which there's a laser-tag sort of game in which attacks are blocked by teammates with mirrors. They end up using their sports gear and strategy to destroy some other army with its own laser beams.

The tag line at the end of the story is the military report submitted, "Upon reflection, [other general's name] surrendered."

Found it: Bullard Reflects and it is by Malcolm Jameson from 1941 (thanks google +straightdope )
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Re: 1441: Turnabout

Postby rmsgrey » Fri Oct 31, 2014 2:19 pm UTC

Wasn't there a fairly early episode of Big Bang Theory where the guys did fire their death ray at the moon?

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Re: 1441: Turnabout

Postby Cloudster » Fri Oct 31, 2014 2:20 pm UTC

Definite LOL out of me, my wife did an 'Oookay' which is odd because she actually uses the retroreflectors on a regular basis. Our last APOLLO run, Tuesday night, she hit all five (three Apollo, two Lunakhod) but she said it was a bit of a struggle.

Since the APOLLO laser pulses at 20 hz, you'd have to be very fast with the 'pew-pew' sounds to sync properly.

(and the Big Bang Theory segment was done after their science adviser saw a talk by the head of the APOLLO program, Dr. Tom Murphy, UCSD)

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Re: 1441: Turnabout

Postby SpringLoaded12 » Fri Oct 31, 2014 2:22 pm UTC

PinkShinyRose wrote:
Klear wrote:Works even better with a Portal Gun.

Wait, can you fire portals through portals?

Nope, but moon rocks conduct portal energy or whatever.
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Re: 1441: Turnabout

Postby FrobozzWizard » Fri Oct 31, 2014 2:47 pm UTC

I really think one of those two guys should have been a black head or at least Black Hat Guy to emphasize the Spy vs Spy feel of this one.

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Re: 1441: Turnabout

Postby alanbbent » Fri Oct 31, 2014 3:16 pm UTC

PinkShinyRose wrote:
Klear wrote:Works even better with a Portal Gun.

Wait, can you fire portals through portals?


Not in Portal, but I've heard that this was possible in Narbacular Drop.

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Re: 1441: Turnabout

Postby david.windsor » Fri Oct 31, 2014 3:26 pm UTC

I thought retroreflect sent the light back along the same path... the angle of the beam in frame 3 and 5 should have matched.
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Re: 1441: Turnabout

Postby Invertin » Fri Oct 31, 2014 3:50 pm UTC

da Doctah wrote:
bachaddict wrote:When I read the title I thought 'Roundabout' and expected something like Traffic Lights.


I correctly read "Turnabout" and expected a reference to Thorne Smith.


I was expecting Ace Attorney, to be honest.

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Re: 1441: Turnabout

Postby ucim » Fri Oct 31, 2014 3:51 pm UTC

Cloudster wrote:Definite LOL out of me, my wife did an 'Oookay' which is odd because she actually uses the retroreflectors on a regular basis.
Yeah - didn't she say (in the movie) that getting one photon back out of a whole bunch of laser pulses is typical? (Enjoyed the film, btw)

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Re: 1441: Turnabout

Postby Biliboy » Fri Oct 31, 2014 5:29 pm UTC

cellocgw wrote:There's an ancient SF short story (my guess is 1950s) in which there's a laser-tag sort of game in which attacks are blocked by teammates with mirrors. They end up using their sports gear and strategy to destroy some other army with its own laser beams.

The tag line at the end of the story is the military report submitted, "Upon reflection, [other general's name] surrendered."

Found it: Bullard Reflects and it is by Malcolm Jameson from 1941 (thanks google +straightdope )



Does it count as a GOOMHR moment if I just read that story? Found an old anthology (A Treasury of Great Science Fiction edited by Anthony Boucher) that has that story in it just the other day.

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Re: 1441: Turnabout

Postby mikrit » Fri Oct 31, 2014 7:06 pm UTC

Sandor wrote:The lightspeed round trip time to the moon and back is about 2.6 seconds. I was wondering if the two of them had time to say what they say.

From my count, the pair say 13 syllables in total in those 2.6 seconds, or 5 syllables/second, or 300 syllables/minute. From what I can gather, 300 syllables/minute is a fast talking rate (for a speech), so it's just about feasible.

Never mind what's possible. In adventure comics, the hero always has time to say something witty.
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Re: 1441: Turnabout

Postby lgw » Fri Oct 31, 2014 8:12 pm UTC

The Earth rotates at nearly 2.8 megafurlongs/fortnight at the equator. In the 2.6 seconds it would take your shot to reflect off the moon, you'd have moved 6 furlongs (over a kilometer, for those using deprecated units), at the equator, or a fair portion of that at temperate latitudes.

Sorry, Randal, you goofed on the technical details on this one. (Not that I'd complain about it for any other webcomic, but XKCD sets a high bar).
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Re: 1441: Turnabout

Postby NoMouse » Fri Oct 31, 2014 8:16 pm UTC

Moon shot first!
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Re: 1441: Turnabout

Postby Klear » Fri Oct 31, 2014 8:39 pm UTC

NoMouse wrote:Moon shot first!


Stupid skycircle...

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Re: 1441: Turnabout

Postby xtifr » Fri Oct 31, 2014 8:58 pm UTC

mikrit wrote:
Sandor wrote:The lightspeed round trip time to the moon and back is about 2.6 seconds. I was wondering if the two of them had time to say what they say.

From my count, the pair say 13 syllables in total in those 2.6 seconds, or 5 syllables/second, or 300 syllables/minute. From what I can gather, 300 syllables/minute is a fast talking rate (for a speech), so it's just about feasible.

Never mind what's possible. In adventure comics, the hero always has time to say something witty.


That's because Talking is a Free Action.

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Re: 1441: Turnabout

Postby keithl » Fri Oct 31, 2014 11:22 pm UTC

lgw wrote:The Earth rotates at nearly 2.8 megafurlongs/fortnight at the equator. In the 2.6 seconds it would take your shot to reflect off the moon, you'd have moved 6 furlongs (over a kilometer, for those using deprecated units), at the equator, or a fair portion of that at temperate latitudes.

Collimation, reflector size, and atmospheric refraction issues aside ... the lunar retroreflectors were made by the Aerospace Systems Division of Bendix, which disappeared in a merger in 1983. Let's presume that the retroreflectors were not precisely "retro", 3 microradians off, exactly enough to bounce the magically collimated beam precisely into the back of "what?" guy. Perhaps the same ever-so-slightly inept optical engineer moved to Perkin Elmer after the merger, and designed the mirror-figuring system for Hubble.

Let's hope this hypothetical engineer is retired, and isn't working at Ball Aerospace on the mirror for the Webb.

We can presume that "floor" guy is an extremely fast thinker and figured all this out, since he developed nanoradian aiming skills (to hit a retroreflector 380,000,000 meters away with sub-meter accuracy) between his first and last shot.

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Re: 1441: Turnabout

Postby addams » Sat Nov 01, 2014 4:52 am UTC

david.windsor wrote:I thought retroreflect sent the light back along the same path... the angle of the beam in frame 3 and 5 should have matched.

It might have matched if he had retroreflective gear.
He says retroreflective, really fast.

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Re: 1441: Turnabout

Postby orthogon » Sat Nov 01, 2014 10:44 am UTC

obfpen wrote:* They're not called retroreflectors because they reflect light back to Earth, but because they're from the 60s and 70s. Ask a hipster.
I see, so it's a retro reflector as seen on the back of this Raleigh Chopper?
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Re: 1441: Turnabout

Postby addams » Sat Nov 01, 2014 3:20 pm UTC

Yes.

Real retro reflective gear is Amazing stuff.
Today, in the future, it can be tough, durable and rigid.
That stuff is on Road Ways.

Today, in the future, it can be tough, light and soft.
That stuff is on Moto riding gear, arm bands, the bottom of full short skirts.

That stuff is Great!
It takes very little light to make it stand out in a crowd.

And! It is, now, cheep.
In the US, I have seen retroreflective gear in the $ Store, for a dollar.
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Re: 1441: Turnabout

Postby Reecer6 » Sat Nov 01, 2014 10:03 pm UTC

Invertin wrote:I was expecting Ace Attorney, to be honest.


It's incredibly obvious he didn't shoot at a retroreflector on the moon, but on Apollo Justice. Clearly.

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Re: 1441: Turnabout

Postby clydwich » Sat Nov 01, 2014 11:16 pm UTC

The laser pistols that they use must have very focussed beams....
When I was studying Surveying, the faculty had a laser canon, for satellite surveying (shooting laser beams at the moon actually). They told us that even with the focussed laser light that they used, when they would shoot a laser pulse that had the dimensions of a garbage can, it would have spread to a form that they described as a "hockey puck" with the same thickness as the original pulse, but with a radius of about a kilometer.....

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Re: 1441: Turnabout

Postby Nyktos » Sun Nov 02, 2014 11:50 pm UTC

Reecer6 wrote:
Invertin wrote:I was expecting Ace Attorney, to be honest.


It's incredibly obvious he didn't shoot at a retroreflector on the moon, but on Apollo Justice. Clearly.
Apollo's an orphan. He was adopted by the Justice family, but his biological father was a Mr. Retroreflectors.

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Re: 1441: Turnabout

Postby gmalivuk » Mon Nov 03, 2014 3:00 pm UTC

david.windsor wrote:I thought retroreflect sent the light back along the same path... the angle of the beam in frame 3 and 5 should have matched.

It looks to be as close to the same angle as is possible in a hand-drawn stick-figure comic.

(It doesn't reflect on the same path, but on a parallel one.
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Re: 1441: Turnabout

Postby jpvlsmv » Mon Nov 03, 2014 3:37 pm UTC

cellocgw wrote:There's an ancient SF short story (my guess is 1950s) in which there's a laser-tag sort of game in which attacks are blocked by teammates with mirrors. They end up using their sports gear and strategy to destroy some other army with its own laser beams.

The tag line at the end of the story is the military report submitted, "Upon reflection, [other general's name] surrendered."

Found it: Bullard Reflects and it is by Malcolm Jameson from 1941 (thanks google +straightdope )

There's also Ildiran Jousting in Anderson's Saga of Seven Suns, where laser pikes and reflective armor are used. (A particularly skillful player will reflect an attacker's own beam against them)

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Re: 1441: Turnabout

Postby HES » Mon Nov 03, 2014 8:28 pm UTC

gmalivuk wrote:[It doesn't reflect on the same path, but on a parallel one.

How much will the earth have moved during the travel time?
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Re: 1441: Turnabout

Postby brenok » Mon Nov 03, 2014 8:34 pm UTC

HES wrote:
gmalivuk wrote:[It doesn't reflect on the same path, but on a parallel one.

How much will the earth have moved during the travel time?

That'd depend on the latitude. At the equator, about 1.14km

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Re: 1441: Turnabout

Postby Whizbang » Mon Nov 03, 2014 8:36 pm UTC

The reflector dish must be slightly angled, then.

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Re: 1441: Turnabout

Postby HES » Mon Nov 03, 2014 8:47 pm UTC

But the moon is moving too, so how does that affect it?
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