[ExI] Radio talk on life extension/cosmism

[Anders Sandberg]

Actually, while the universe as a whole may be limitless, we are 
actually likely stuck in a finite patch.

The reason is the accelerating expansion. Even if we spread at light 
speed we could only reach 15 billion light years away ("the affectable 
universe" in Toby Ord's terminology). That is still 6.5 billion galaxies 
and much larger than the 300 million lightyears "end of greatness" 
homogenity scale (Laniakea is just 260 million and the Virgo cluster 
just 7 million lightyears).

The 46 billion lightyear radius of the currently observable universe is 
expanding with time, and will eventually reach 62 billion lightyears. 
But that is relative to Earth: were we to expand across the affectable 
universe we would add 15 billion lightyears in all directions - things 
that can be seen by the colonies, even though the information can never 
reach Earth.

Note that if you want to exchange an infinite number of signals from the 
frontier to your core you will be stuck in a gravitationally bound 
supercluster, a few million lightyears across.

So our future universe may be unbounded in time, but not in space.

(A lot of these measures need defining in a bit more detail, since we 
are dealing with expanding coordinate systems; I have used co-moving 
spatial coordinates here, since they are the most reasonable when you 
care about the material stuff inside the universe.)

On 2016-03-23 08:11, Dan TheBookMan wrote:
> On Mar 22, 2016, at 1:14 PM, BillK <pharos at gmail.com 
> <mailto:pharos at gmail.com>> wrote:
> Sort of linked.......   :)
>>
>> <https://briankoberlein.com/2016/03/22/beyond-the-universe/>
>>
>> Quote:
>> the known universe is about 93 billion light years in diameter. As
>> large as that is, it’s only the portion of the Universe we can
>> observe. The total Universe extends beyond our horizon. Just how far
>> it goes is an interesting question.
>>
>> There are indications that the Universe extends far beyond what we 
>> can observe.
>>
>> the short answer for the size of the Universe is that it’s huge.
>> Likely very, very, very huge. Possibly infinite.
>
> I still default to infinite. ;)
>
> Regards,
>
> Dan
> Sample my Kindle books via:
> http://author.to/DanUst
>
>
>
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-- 
Anders Sandberg
Future of Humanity Institute
Oxford Martin School
Oxford University

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