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Offline TomInAustin

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Re: Perfect experiment
« Reply #20 on: April 25, 2018, 06:58:11 PM »
From a practical point of view, you're going to have a hard time performing the laser experiment at distances on the order of thousands of meters.

I don't know the perceived brightness of a 2W blue laser vs a 300mW green laser (although I suspect the green one is brighter) and whether you'll even be able to see it in daylight, but that's irrelevant. I don't think you'll be able to see much other than a big blob of light at the other end. Lasers typically have a beam divergence of about 0.5mrad to 1mrad. If you're going to shine it at a distance of 1000 meters, you're looking at anywhere between a 0.5m and 1m wide blob of light.

First, it needs to be done at night.  The beam is not visible at all in sunlight but very bright in the dark.  The blob at the end is fairly round and would show either a full circle or a cut off one if the curvature is there.   When a buddy of mine and I first got these stupid expensive toys, we shined then on a cylindrical water tower from various distances and checked what it looked like on the receiving end.   Curvature was not relevant as the tower is on a hill (as they are always on a high point).

I chose the lake as the venue since it should be flat if the earth is flat.  The problem would be a big enough target to catch the beam.
Do you have a citation for this sweeping generalisation?