[ExI] Breakthrough Starshot - To The Stars!

Rafal Smigrodzki rafal.smigrodzki at gmail.com
Tue Apr 26 06:37:30 UTC 2016


On Mon, Apr 25, 2016 at 8:13 AM, Anders Sandberg <anders at aleph.se> wrote:


> Hmm. If you want to achieve velocity V and accelerate during a boost at
> acceleration a, you will need time V/a. During this time it will move over
> a distance (1/2)at^2 = (1/2)V^2/a. The starshot aims at something like
> 60,000 km/s using 2 minutes of 500,000 N/kg acceleration. So it will move
> 3,600,000 km during those two minutes.
>
> A diffraction limited beam will have an angle given by lambda/pi w, where
> w is the radius at the beam  waist. Assuming an optical beam with
> wavelength around 500 nm and a kilometre-sized "launchpad", the angle
> becomes on the order of 1.6*10^-10 radians. The Rayleigh length is l = pi
> w^2/lambda = 6.28e12 meters, and the radius scales as w*sqrt(1+(d/l)^2).
> With for the above numbers become 1000.00016 m. In short, there is not any
> serious dispersion to worry about.
>

### It appears that my intuitions were incorrect and thank you for doing
the math.

This is good: We don't need multiple launch lasers to colonize other stars,
so we'll get there sooner.

Rafał
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