A rocket is preparing for journey from Earth to Alpha Centauri. The Earth and Alpha Centauri systems are at rest with each other and have syncronized their clocks to time t=0.(adsbygoogle = window.adsbygoogle || []).push({});

________E__________________________________________________A (distance: 4 ly)

________R

Rocket speed is known to be 0.8c. From EA frame, we calculate that the journey will take 5 years. The A clock will show 5 years and rocket's clock 3 years when the rocket arrives (1).

Rocket starts its engines and accelerates quickly to 0.8 c.

______<-E____________________________<-A (distance: 2.4 ly)

________R

From rocket's perspective, the travel will take 3 years. A's clock will advance only 1.8 years => to be consistent with (1), A's clock has to show 3.2 years after the rocket has started its engines.

Ok so far, but now the rocket driver has second thoughts and stops. We are again in situation

________E__________________________________________________A (distance: 4 ly)

R

A's clock seems to show t=0 again.

Needless to say, the rocket can accelerate and stop again any number of times. From R's perspective, during acceleration A's clock advances 3.2 years; during braking, the A's clock gets back the same 3.2 years.

Say, a great lottery is drawn in Alpha Centauri at t=1 years. Its winner will get financically very independent, possibly happy too. During every rocket acceleration, the lottery is drawn; during every braking, time is reversed. Of course the rocket cannot directly observe this, but in principle,

this is really happening.

When accelerating and braking back and forth, will the same person/alien will every time? Will the lottery numbers be the same? If yes, should we believe in destiny? If not, do the several winners each continue their lives somewhere in the timespace?

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# Alpha Centauri lottery

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