[ExI] Expansion of the Universe

[Anders Sandberg]

On 2012-12-29 10:19, BillK wrote:
> So much for humanity expanding throughout the universe.
> If humanity is ever able to reach another galaxy, we'll only get to
> the nearest few out of 200 billion galaxies.

Sure. Just 2e22 stars. And about a hundred times as much gas and dark 
matter.

According to our calculations (they are in my paper with Stuart 
Armstrong), what matters the most is expansion velocity, not how long we 
delay. Since the remote galaxies will be reached in billions of years 
anyway a delay of a million years does not matter much if it leads to a 
bit faster probes. This is also favors small and fast probes with few 
generations and high fan-out rather than big and slow ones that spread 
shorter distances.

An important question is what you want to use the mass for. If you want 
to turn it into hedonium and do not care about long-range communications 
you should try to get as much as possible. If you want a cohesive 
civilization you will not need much beyond a supercluster anyway, since 
the other superclusters will drift apart and lose causal contact with 
you. So hedonists might be more motivated to spread far and wide.

-- 
Anders Sandberg
Future of Humanity Institute
Oxford University