More power? How about more cowbell!

I've got a fever, and the only prescription is MORE LASERS!

WALOOB!
On so many levels it's nonsense...

"A good one has a tight enough beam to hit the moon"
Maybe if we were ouside the atmosphere.. Ok I haven't done the maths and I'm willing to be proved wrong, but it doesn't take much dust and cahnges of refractive index to move a beam by a few seconds of arc, not to mention how steady you can hold your aim.
Consider an Olympic archer aiming at the gold at 70m...

Even the effect of your heartbeat will be making the beam shift enough to miss the moon
Yeah, no need for maths... it's complete tosh.
Maybe if we all throw a brick at it?
Del

It's not that hard to hit the moon with a laser, just look into lunar laser ranging.

With that said, I'm still willing and ready to get behind the "we all throw a brick at it" strategy.

Isn't that what tripods are for? Just sayin'

I thought the tripods came from Mars. Jus' sayin'

Aw, come on. How many Olympic athletes are able to throw a brick so hard that it exceeds escape velocity?

Cuz the folks they were throwin' them at couldn't run like Usain Bolt?

Would these bricks be launched from a mortar?

or ?

Only if they are Limey bricks

It's about time someone started a War with the moon. It's getting a little too cocky up there.

They'll set the dragon on you !

"It's about time someone started a War with the moon."

Heck, we're already arse-deep in one with Mars - and no exit strategy!

Columbian bricks, more like.

The real trick would be focusing the beam in such a way as to prevent it from spreading out over the 238,900 miles it travels to get there.

Aw c'mon,
Shirley, a bean can with a nail hole in the bottom should do the trick
Del

Aw c'mon,Shirley,
YES, and dont call me Shirley (could not help myself)

For the laser, the beam is tight enough that it only spreads out with a diameter of about 7 km by the time it reaches the moon. For the other sources of light used, I can't get a solid figure of how much dispersion would occur over that much of a distance, though I've heard through the grapevine (aka no citation) that an IMAX laser pointing towards the sky can be seen from space.

No prob. We just send the lasers there.

Unfortunately, the beam disperses even further on the return trip back to earth, so it's hard to believe that it would be strong enough to put a hole in an automobile like this. Also, would you care to explain your hypothesis on how shining a laser at the sun increases time for enough to allow a car to rust out, and two mighty oak (maple? cider?) trees to fully grow?

I'm quite curious.

Not so fast, Louis.

"Powering this ______ would use up Earth's oil reserves in approximately two minutes ..."

Fair enough, I just didn't want to spoil it

Here's the full quote:

"Ok, let's mount a megawatt laser on every square meter of the surface of Asia. Powering this array of 50 trillion lasers would use up Earth's oil reserves in approximately two minutes, but for those two minutes, the Moon would look like this:

Obviously, this would never happen for more reasons than I'm willing to count (let's start with: "how do we get a megawatt laser to every person?), but it's still neat to think about.

Actually, I'm curious. The author of the post makes note of the larger factors that have to be ignored for this to happen, but what're some of the minute ones? Kind of wonder who can possibly come up with the most mundane detail missing that would stop this whole thing from carrying on

I marked it off-topic, two. Forgot to press the Off-Topic button. Sorry 'bout that.

The Moon is not a flat surface, a light shone in the center might reflect back, but further out on the curvature and it will be reflected towards Venus or anywhere but Earth.

Can you then explain the image in #12 (marked 'Target') where the moon is illuminated by the sun from stage right?

The Moon's surface is like a quasi-lambertian reflector (like a snowball), not a specular reflector (like a shiny, round Christmas ornament). The light gets scattered through tau steradians (2 pi steradians).

Ah, but what about reflection of impacting bricks?
Del

Don't look up!

Once the bricks were over the gravity col part-way between the earth and the moon, they would be beyond the point of no return. Any reflected brick would eventually fall back to the lunar surface inside its gravity well. Inelastic collisions and conservation of energy does the rest. The principle issue seems to be one of the bricks arriving at the escape velocity of the moon, and either burying themselves below the surface or fragmenting and not surviving the experience. Unless they were very well-made bricks - simple Fletton bricks might not be strong enough. The Jury is out on class A engineering bricks, as one might expect. Regardless, life forms on the lunar surface might be bricking it...

GA and thank you. I'm too old and my mind has lost the flexibility to dig through the math without a lot of work, but the examples are more than ample, in fact, they are shining examples.

I think this whole thing pretty well sums up how incredibly small we are and that for all of our supposedly massive amounts of energy we have used over the last 150 years on this planet from fossil fuels and everything else we literally cant hold a candle to the basic energy levels the sun dumps on the moon in just a period of several minutes.

on a Clear day or cloudy day? if it rains? how much particles in the air? most laser pointers are in the milliwatts, wouldn't most energy be dispersed before it reaches the moon?

This is pretend.

Just read the link, it describes the basic concepts. Also, yes, it's pretend :D

....So, i'm not getting a YAL-1 then?

oh! then depending on the amount of lasers

Is that what's left of your bowling ball? DAMN!!

Can't - Nanny won't let me.

Only those on the moon-side of earth try.

They already tried? CR4P!

I'm still waitin' on my 500-TW laser from ThinkGeek.

Glad I read the whole thread - I was going to ask:

a) how much fuel is needed to move the population of the "moon-dark" side of the earth to the moonlit side. (KRIS: where's that bl00dy population distribution formula you've been working on for the past 3 years. I've finally found a use for it!)

b) How are they going to get home when we've used up all the fuel?

c) how much fuel will be need to make 7 billion lasers? And how does this affect the effect (not that I know what the effect is, since Nanny won't let me look at pictures, well some pictures).

d) WHY?!?!? For Dog's sake, why?!?!?!

_{<sigh> And Savvy wonders why engagement on the site os falling...}

Due to a #1 comment, it resides on the back of the stove. Said comment left me feeling so, so...hurt _{might be fibbing*.....}

Going home ? No, that's when the lasers are turned and we solve world population problems !

_{* but I'm not saying which bit(s) are big fat fib}

a) We're assuming the time when the moon is most visible to the most amount of people.

"Since about 75% of the world's population lives between 0°E and 120°E, we should try this while the Moon is somewhere over the Arabian Sea.

We can try to illuminate either a new moon or a full moon. The new moon is darker, making it easier to see our lasers. But the new moon is a trickier target, because it's mostly visible during the day-washing out the effect.

Brightness aside, an ideal time would probably be 2:00 PM EST on December 27th, 2012, when a full moon will be high in the sky above Mumbai and Islamabad. At that point, the Moon will be visible to approximately five billion people-most of Asia, Europe, and Africa-about as many as can ever see it at one time."

b) On the offchance that we did in fact bring everyone to the same spot, the notion of bringing everyone back was already brought up. Spoiler alert: nothing good comes form it

c) Unreal amounts. At one point, the hypothetical scenerio takes a laser which only exists in a handful of areas and places one on every square meter of asia.

d) Just for fun, it's nice to muse over silly things sometimes. Also, dogs are terrible, cats are better.

e) Lists are better in 5's

a) Most isn't all. I do so abhor inexactitude in problem definition.

b) I've already said Nanny won't let me visit xkcd. If you're going to quote, then post it here.

c) Is the laser smaller than one square meter?

d) But cat backwards is tac. Dogs are lovely, just in a different way from cats.

e) No they're not

f) most definitely not

g) even seven's not good

h) This list is now twice the optimal length.

There's nothing inexact about the problem definition. It is completely specified as stated. Truly! Everyone can *aim* laser pointers at the Moon right where they are, without even getting out of bed. The problem statement does not require that the Moon even be visible, but only that you aim your laser pointer at the Moon. For some it means pointing the laser toward the ground, for others, at a more oblique angle; but all can aim and that is all that is being asked of them. The problem statement does not even require that you actually *fire* your laser, moreover, and so the answer to the question is clearly "No." What follows after that is where the inexactitude creeps in, because xkcd's answer is based on an assumption of what was being asked, rather than on what was literally, exactly being asked. It would seem, then, that inexactitude has its place, yes? It is the implicit filling-in of blanks that transforms the silly, literal, exact problem statement into an interesting problem statement, colloquially understood to be the Real Question Behind the Question. :-)

In English Roses' defense, she(?) can't actually see the article due to an oppressive nanny, which might be influencing her(?) responses

But yes, I agree with your eloquent explanation of what's going on here

So if I shoot europium because Kris is hiding behind him, I can't be held responsible for killing e because I was aiming at Kris?

Sorry, that argument just doesn't stand up, especially when talking about aiming a piddling laser beam at a s*dding great celestial body.

Get out there and pick up them tumbleweeds, they's makin' the place look untidy. Dang Texans!!

[Shouldn't you have a Lone Star under your avatar??]

You'ld get laughed out of town for missing something the size of my ego.

I wouldn't need a gun to hit your ego - the sharp edge of my tongue is sufficient...and no-one else would get hurt in the process (althoguh they would probably be afraid...very afraid!)

Anyhoo...I think the gun would be more usefully traded for a flamethrower...that way you couldn't put off my aim with your cute fluffy tail!

Sybil ?

Screw the flamethrower. I wanna see the Tongue Act.

Be still my palpitating Lone Star heart! Tumbleweeds!

Gotta go to Colorado for those. Dang! Gosh sakes! Don't you know anything about World Geometry?

<-- note sublime hint of aforementioned Act.

Tee heee - I also know how much the idea of tumbleweeds in Texas gets you going!

Move 'em up, ride 'em in, ride 'em in, cut 'em out.....c'mon Yeller(rose) up and at 'em!

is going to have to wait for the next time the CR4 minibus outing.

(I thought the hint was more ridiculous than sublime )

Blame sublimation!

Hey- watt about using those airborne lasers they're scrapping!

just billions of dead batteries.

Very entertaining!