Talk:Ember/@comment-28666529-20171121062933/@comment-28666529-20171122214403

Well if we want to get technical the sun isn't exactly like an laser. Although it's distance from us makes it similar because we only see photons traveling in parallel when they reach us. However it starts out more like a light bulb.

If you think of a light bulb, the photons flying off will go in all different directions. The electromagnetic waves are considered "incoherent" and the light intensity drops off by the inverse-square law. Basically that means that if you measure one square inch of light at a certain distance, then at double that distance the intensity would be 1/4, (over 2 inch by 2 inch square). At 3 times the distance the intensity would be 1/9th. (over a 3 x 3 inch square). And so on.

However with a laser all the photons have been aligned to travel in the same direction. The electromagnetic waves are considered "coherent". So if you shine a well focused laser through a vacume you get almost exactly the same intensity at 10 feet as you get at 10 miles.

For a laser the main reason it does lose intensity is from the atmosphere. However it does not obey the inverse square law so it maintain most of the intensity for miles.