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1441: Turnabout

Posted: Fri Oct 31, 2014 5:54 am UTC
by Chris Dude70
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?
>.>
<.<

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 6:32 am UTC
by bachaddict
When I read the title I thought 'Roundabout' and expected something like Traffic Lights.

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 6:42 am UTC
by rhomboidal
I'll bet astrophysicists mumble "pew pew pew pew" every time they test the retroreflectors.

That's no moon!

Posted: Fri Oct 31, 2014 7:05 am UTC
by Eternal Density
I am okay with this.

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 7:38 am UTC
by Pfhorrest
It's a fair play.

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 8:20 am UTC
by Sandor
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.

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 9:30 am UTC
by obfpen
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.

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 9:56 am UTC
by da Doctah
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.

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 10:02 am UTC
by Klear
Works even better with a Portal Gun.

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 11:28 am UTC
by schapel
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!"

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 12:40 pm UTC
by PinkShinyRose
Klear wrote:Works even better with a Portal Gun.

Wait, can you fire portals through portals?

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 1:21 pm UTC
by mathmannix
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)

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 1:52 pm UTC
by cellocgw
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 )

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 2:19 pm UTC
by rmsgrey
Wasn't there a fairly early episode of Big Bang Theory where the guys did fire their death ray at the moon?

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 2:20 pm UTC
by Cloudster
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)

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 2:22 pm UTC
by SpringLoaded12
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.
The white paint on portal-applicable walls is made from moon rocks.

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 2:47 pm UTC
by FrobozzWizard
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.

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 3:16 pm UTC
by alanbbent
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.

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 3:26 pm UTC
by david.windsor
I thought retroreflect sent the light back along the same path... the angle of the beam in frame 3 and 5 should have matched.

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 3:50 pm UTC
by Invertin
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.

The different kinds of nerd.

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 3:51 pm UTC
by ucim
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)

Jose

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 5:29 pm UTC
by Biliboy
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.

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 7:06 pm UTC
by mikrit
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.

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 8:12 pm UTC
by lgw
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).

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 8:16 pm UTC
by NoMouse
Moon shot first!

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 8:39 pm UTC
by Klear
NoMouse wrote:Moon shot first!


Stupid skycircle...

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 8:58 pm UTC
by xtifr
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.

(Warning: Link goes to TV Tropes, a site that may eat your brain, ruin your language, and cause hours to disappear before you notice.)

Re: 1441: Turnabout

Posted: Fri Oct 31, 2014 11:22 pm UTC
by keithl
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.

Re: 1441: Turnabout

Posted: Sat Nov 01, 2014 4:52 am UTC
by addams
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.

It's a game.
Adults need to play.

(shh) We put water in syringes and stalked one another, sometimes.
Don't Panic. We took the needles off.

Re: 1441: Turnabout

Posted: Sat Nov 01, 2014 10:44 am UTC
by orthogon
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?
Image

Re: 1441: Turnabout

Posted: Sat Nov 01, 2014 3:20 pm UTC
by addams
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.

Re: 1441: Turnabout

Posted: Sat Nov 01, 2014 10:03 pm UTC
by Reecer6
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.

Re: 1441: Turnabout

Posted: Sat Nov 01, 2014 11:16 pm UTC
by clydwich
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.....

Re: 1441: Turnabout

Posted: Sun Nov 02, 2014 11:50 pm UTC
by Nyktos
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.

Re: 1441: Turnabout

Posted: Mon Nov 03, 2014 3:00 pm UTC
by gmalivuk
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.

Re: 1441: Turnabout

Posted: Mon Nov 03, 2014 3:37 pm UTC
by jpvlsmv
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)

Re: 1441: Turnabout

Posted: Mon Nov 03, 2014 8:28 pm UTC
by HES
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?

Re: 1441: Turnabout

Posted: Mon Nov 03, 2014 8:34 pm UTC
by brenok
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

Re: 1441: Turnabout

Posted: Mon Nov 03, 2014 8:36 pm UTC
by Whizbang
The reflector dish must be slightly angled, then.

Re: 1441: Turnabout

Posted: Mon Nov 03, 2014 8:47 pm UTC
by HES
But the moon is moving too, so how does that affect it?