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It will be 0.35 of a mile, plus 3 ft.
Seany's post about a laser his friend bought prompted this question.http://www.thenakedscientists.com/forum/index.php?topic=13568.0Assuming this device really does have a range of 50 miles and was shone horizontally from the waist (say 3ft above the ground), at what altitude would the beam be 50 miles away?
Quote from: turnipsock on 28/03/2008 11:45:40It will be 0.35 of a mile, plus 3 ft.How did you work this out? 
The circumference of the earth is 360x60=21,600 miles.
The direct effect of gravity is pretty small but the effect of the refraction is significant. If the earth's atmosphere weree replaced by SO2 which has a slightly greater refractive index, the curvature due to refraction would be roughly the same as the curvature of the earth and light would go right round (ignoring any mountains).
Anyone reading this will wonder what the hell we're talking about. They won't realise a post has been deleted. Well, they will now because I've mentioned it. But they won't know what it said.