2007-12-31 13:05:31 · 2 answers · asked by Ethereal 5 in Science & Mathematics ➔ Physics
Far enough that people have been arrested for shining a laser pointer on aircraft in flight, from the ground.
In practical terms, it is as far as you can see, with appropriate lighting conditions, what you are pointing at to know if the laser pointer is on target or not.
2007-12-31 13:26:20 · answer #1 · answered by Charles M 6 · 1⤊ 1⤋
Lasers are simply in-phase light, which is made of photons. A photon will travel at the speed of light until it collides with something.
So, when you shoot a laser pointer into the sky, some of the photons make it out of the Earth's atmosphere and will continue traveling forever.
However, since the laser isn't perfect, the photons probably came out headed in very slightly different directions. So, even though the beam technically exists 1000 miles away, it is so spread out that it is probably undetectable.
2007-12-31 21:11:35 · answer #2 · answered by lithiumdeuteride 7 · 0⤊ 2⤋