Journal zptdooda's Journal: Bayes and the universe 1
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Occasionally I consider how minute the probability of actually being here is. The only reason that we can make this observation at all is that being here is a necessary condition.
As the saying goes, âoethe universe is bigâ.
A couple of fairly recent stories PBS: cosmic expansion and Multiple Universes discuss the scale of time and space.
B----------------------------------E
On the time line, our universe started about 13B years ago (B). But things wonâ(TM)t reach steady state â" which is when the universe gets really boring - for trillion trillions of years (E). By steady state I mean the time of the last significant event, such as the last proton decay. All black holes would have evaporated. I know this ignores activity causing cosmic expansion pressure. The universe would largely be a spray of subatomic particles. Would there be anything else? Please let me know. Iâ(TM)m interested in knowing whether thereâ(TM)d be chunks or purely a spray.
Weâ(TM)re so close to the beginning of the universe that I consider us to still be in a stage of the big bang. For most of the universeâ(TM)s time, it will be a dark spray.
Now think of how wide a time slice of the above scale that any/all of us are available to observe this situation and divide by the total expected nonboring lifetime of the universe.
Categories of reasons for the preposterous unlikelihood of being here include:
- the six constants weâ(TM)ve heard so much about
- the tiny fraction of time that weâ(TM)re here to observe this
- the chance of any of us actually being born (that was a heck of a race each of us won to start our lives â" phew!)
The independent chance of me or you (in particular) observing the universe is to quote the cliché vanishingly small.
But it all comes down to Bayesâ(TM) Theorem. Thatâ(TM)s the sole reason I have for observing right now.
!RRR (Score:2)