141–150 of 274 posts
So, how is a tiny smartphone-sized probe supposed to transmit data back to Earth from 4.37ly away?
Why don't we focus and reflect the sun's rays instead? Or even combine this and the traditional rocket method by putting the emitters in space to catch the sun and push these tiny craft after they've been shot from the Earth by the zillions in a single satellite. That way we deal with two big problems at once: generating laser energy sufficient for escape velocity, and focusing lasers through an atmosphere layer. Bet…
Apparently you can't collimate sunlight because it's not a point source. But I've been unable to find an explanation as to exactly why which I can understand, because this aspect of optics is deeply unintuitive, but the magic phrase to search for is 'conservation of éntendue'. If you find one, let me know.
Earlier quoted context omitted.
> Oddly the most practical use for this is as an interstellar weapon. I completely don't advocate this, but the 9-year-old-boy part of my brain thinks it'd be pretty awesome to announce our presence to the universe by attacking a star system.
One of the explanations of why we are not seeing evidence of ETs is that everybody is hiding and afraid they might get bombed by their neighbors; that's because bombing your neighbors is orders of magnitude easier to do than visiting them -- you don't need to solve the problem of decelerating on the other end for one thing.
So the whole thing should weigh in the order of several grams, yet it should be able to deflect 100GW of incoming radiation near perfectly (otherwise it will instantly vaporize) while maintaining structural integrity under the acceleration of 60,000g for two minutes? And whatever laser sources we're using must track this smartphone-sized object during these two minutes across several million kilometers. Perfectly. (I…
If the laser is tune-able, you could slowly increase the output-frequency based on how fast you expect the target to be moving at the time the light hits. This would counteract the Doppler effect and supply a consistent frequency to the target.
Earlier quoted context omitted.
Yep. "Use a material with better than 99.999% reflectivity. Usually, highly reflective surfaces are dielectric mirrors, which are composed of ‘sandwiches’ of material, with each layer reflecting back a modest fraction of the total. Each layer needs to be at least a quarter of a wavelength thick. The weight can be reduced by using a monolayer with high reflectivity at the correct wavelength. Based on recent research,…
IIRC, Robert Forward was writing about sails using dielectric mirrors with holes in them back in the 80's.
So the whole thing should weigh in the order of several grams, yet it should be able to deflect 100GW of incoming radiation near perfectly (otherwise it will instantly vaporize) while maintaining structural integrity under the acceleration of 60,000g for two minutes? And whatever laser sources we're using must track this smartphone-sized object during these two minutes across several million kilometers. Perfectly. (I…
And where does the reflected laser light go? Back to earth if it's reflected 180 degree. And how does a device weighing a few grams emit a signal capable of detection back on earth? The Voyager probes are over half a light-day from earth but they have rather large antennas.