Google Arthur C Clarke's "A Slight Case of Sunstroke". I think that Clarke's idea has been analyzed in the scientific literature, as well. I see several problems: 1. It's difficult enough to point a mirror (or a laser) a few hundred feet and keep it on target. An analogous problem is keeping high-powered binoculars focused on a target -- it's basically impossible without a tripod, at least. 2. How can you tell if _your_ beam is hitting the target? 3. Atmospheric problems. Modern telescopes use lasers to test the atmosphere & correct using 'adaptic optics'. That's a bit expensive for every single person to have with their mirror. 4. Various refractive & diffractive effects. Since these mirrors aren't lasers, they have a multitude of wavelengths, so your 'focus' 'point' would be a pretty big volume. Volume grows cubically, while surface area grows quadratically, so your spaceship might be able to 'hide' in plain sight. 5. Cosine atmosphere problem. The further you are from the closest point on the Earth's surface, the more atmosphere you have to go through. This would remove most of the UV, at least. 6. The laser ignition project that the U.S. has spent billions on already may be shut down due to lack of results. And they're only trying to hit a target right here in California! At 02:07 AM 7/17/2013, Simon Plouffe wrote:
Hello,
I was thinking at how we could procuce energy in a simple way, like having solar ovens with mirrors and such devices. This lead me to Archimedes and the way he used to 'toast' roman warships from the Syracuse citadel, apparently that idea was somewhat validated once, they found a way to toast a pile of plywood resembling a roman ship with plates of metals used at the time.
Anyhow which lead me to think : what about today ?, suppose we would hypothetically having the same kind of threat but from space : an alien warship threatening to zap humans from existence.
What about doing the same thing ? Billion of people using mirrors directly aimed at (more or less precisely) at this alien ship : what would happen ?
More precisely, what would be the effect in energy having let's say 100 miilion mirrors aimed at one point in space toward one of those things, would it do the same thing ? Is this feasible, we would have one shot at it.
This may sound naive, well is it ?
Can someone calculate what output of energy this represent ?
Best regards, Simon PLOUFFFE