friday physics question
 

--this will surely be moved to parf--


If everyone aimed a laser pointer at the Moon at once, would it change color?

given values...... everyone = 80% of all humans in the hemisphere vewing the moon sharks are not involved


all laser pointers have a output of .005w and are red--


discuss-

I think the sunlight on the moon would be too bright but I know nothing really.

who said it was a full moon? ;) I think you conflate "Political" with "stupid" -- I can see how, but they are different.

now, your stupid question: if the moon has an additional color shifted light source will the reflected color shift?

yeah, if a politician promises more good and less bad, will some people believe it?

fixed it for you--

HA! I changed 'other question' to 'stupid question' when you did. :)

If just one person pointed a laser at the moon it would change color... Photons would make their way to the moon surface and there is now more red light on the moon.

I think your real question is not if, but how much i.e. Would the color change be discernible to the human eye.

No, but all the cats on earth would lose their minds.

widebody FTW!

1st, since half the planet is turned away at any given time, those people's lasers would impact the earth, generating huge earthquakes and sunamis. 12 hours later, the rest of the plant would be swamped. Only those living more than 100 miles inland or higher than 300 feet above MSL will be spared.

Red-neck, wrassling fest will be 24/7!

well...if you were to dissect this into a real physics problem, you'll have the following:

"If everyone aimed a laser pointer at the Moon at once, would it change color?"

1) the moon is only visible to 50% of the earth's surface at any one time
2) on that 50% of the surface, only 30% is land on average.
3) on that land portion, there'd a totally undeterminable number of human population. but if we assume a uniform distribution of human population of land (totally idiotic) across that land mass, we could at least have something. so 7bil population uniformly spread across perfectly spherical surface of earth. ~3.5billion can see the moon purely from line of sight, not taking into account surface toplogy, cloud cover, etc etc.

~3.5billion * 5mw laser pointers = 17.5 megawatt output. but this is only output, just the tip of the iceberg.

since the population is spread uniformly across the applicable surface, the laser that's shining directly perpendicular to the surface of the earth is going to be closer to the moon than the laser that's shining tangent to the surface of the earth. within the earth atmosphere, the laser light will be refracted and diminished related to the distance traveled. additionally, temperature, humidity, pollution particulate matter content will all contribute to rob the laser beam of its power.

even once the laser beam has exited the atmosphere, it still has to contend with space dust, although minutely. once it reaches the moon, once again, lunar atmosphere. once it reaches surface of the moon, how lunar rocks/dust reflect the laser beam will need to be taken account of. and again on the trip back to the earth, lunar atmo, space dust, earth atmo, and then finally perceived brightness on observer's retina.


there's a whole lot of data and number crunching to be had. but it's just easier to use an existing item as a base.
there are lunar observation reflectors are planted on the surface of the moon by apollo missions and by soviet missions too. according to wiki Lunar Laser Ranging experiment - Wikipedia, the free encyclopedia, "The reflected light is too weak to be seen with the human eye: out of 10^17 photons aimed at the reflector, only one will be received back on Earth every few seconds, even under good conditions."


so given a return ratio of 1/10^17, and an output power of 17.5megawatt, you will only get to see 0.00000000017 watts returned. so no....you won't see a diff hehe

My dad would call this a Rosebush Question. I used to drive him nuts when I was a kid with some of my questions, such as "If you dropped a bowling ball from an airplane and it landed next to a rosebush, would all the leaves fall off?"

I don't remember asking that particular question, but I do remember asking "If everyone on the planet dropped all their silverware on the floor at the same time, could you hear in on the moon?"

Seriously drove him nuts.

silverware/moon: no cause sound doesn't travel thru vacuum between Earth and Moon

I definitely asked one too many of those questions, one day. I think we were passing through Oklahoma and I asked him why the dirt was red.

"Because GOD made it that way!!!"

The car became very quiet after that...

That didn't occur to my five-year old mind.

My son has been asking crazy questions like this. Then, when I answer him as truthfully as I can, he asks his mother. :rolleyes:

let's try it

Dispersion would scatter the light before it could make the round trip visit and the sun's light would over power anything we could produce.

Dr. Evil:

Any ways, the key to this plan is the giant laser. It was invented by the noted Cambridge physicist Dr. Parsons. Therefore, we shall call it the Alan Parsons Project.

Don't think sorry's easily said
Don't try turning tables instead
You've taken lots of Chances before
But I ain't gonna give anymore
Don't ask me
That's how it goes
Cause part of me knows what you're thinkin'

Don't say words you're gonna regret
Don't let the fire rush to your head
I've heard the accusation before
And I ain't gonna take any more
Believe me
The sun in your Eyes

Chorus:
I am the eye in the sky
Looking at you
I can read your mind
I am the maker of rules
Dealing with fools
I can cheat you blind
And I don't need to see any more
To know that
I can read your mind, I can read your mind

Don't leave false illusions behind
Don't Cry cause I ain't changing my mind
So find another fool like before
Cause I ain't gonna live anymore believing
Some of the lies while all of the Signs are deceiving

I remember my oldest boy asking me why are there people of color. He was 4 at the time, we were in the car and I was driving him to daycare. I paused for a moment and responded: " well Nick, it just not only the color of skin, everyone may have different color eyes, some people have red hair, some blond. If everyone looked the same and thought the same, life would be boring. I think it was God's way of allowing us to get along and learn from each other". I thought to myself, this is a good answer.

My son replied: "oh, ok". "Dad, who's God??. I paused for a moment, the car became quiet. I replied " oh look, we are at your school". I will never forget that day.

LOL! laaaaaaaaaaaaaser!

If you aimed a laser at the moon, don't you need to caluculate the time it takes for the light to travel atthat distance and project where the moon would be at that time. You wouldn't aim the laser directly at the moon, would you?

Yes sound does not travel in a vaccum, however if a tree falls in the forest and no one is there, it doesn't make a sound either.

Sound doesn't travel in a vacuum. I don't know about a vaccum :p (sorry, I couldn't resist).
A better question would be
If a man speaks and his wife is not there to hear him, is he still wrong?

When my kids asked questions and I explained in detail, they lost interest and asked why I talked so much. :(

No.

The moon is only 1.2 light seconds away at most..

yes!!!

It all depends on the quality of the hallucinogens involved.

http://what-if.xkcd.com/13/

Are OP & I the only ones reading xkcd?

it took long enough