Chip Sengravy

If you pointed a laser into a clear sky, would it stop, or would it just carry on until it ended?

just a thought I had today

kingofturds

iTrader: (1)

It becomes so faint until it becomes invisible Got myself a green laser pen ,when its dark you can actually see the beam as a solid

Luminous

iTrader: (3)

If you point it up into the sky, then yes, the beam will end at some point for all practical purposes. The laser light you shine consists of particles/waves of light. Sooner or later these will all interact with atmostpheric particles and lose energy. They will cease to exist as green light when this happens.

It is possible that some of the light will reach space without crashing into anything from the atmostphere, hence why you can see normal lights from space. If the light continues into deep space, where there is nothing for it to crash into, it will exist for all of eternity.

This is how we are able to see history through a telescope. An event that took place many millions of years ago can give off a large explosion (lots of light). That event was so far from the earth that the light from the explosion is just reaching us today, so we can actually see how the universe was many millions of years ago.

Puff The Magic Wagon!

iTrader: (2)

Paradoxically, we can't see the Universe as it is now!! So it may be that 100 years after the light from the centre of the universe was created, a large black hole came and is swallowing the whole place up and following on.

We won't know for 100 years!

HankScorpio

Red laser pointer:
http://www.thinkgeek.com/gadgets/lights/74f0/

Green laser pointer:
http://www.thinkgeek.com/gadgets/lights/5a47/

Blue Laser pointer:
http://www.thinkgeek.com/gadgets/lights/896a/?cpg=36H

Check the prices.

Also, if you want a laugh, go to the t-shirt section and then look at some of the "action shots".

Luminous

iTrader: (3)

Oh yeah, its all screwed up really

So much fun when you really start thinking about it.

Edcase

They emit this proper powerful laser from greenwich observatory at night that basically marks the meantime line. It goes for as far as the eye can see