Happy New Year to all.
On Mon, 13 Dec 1999, Fred Chen wrote:
> Jacques M. Mallah wrote:
> > The Doomsday argument still works. The uncertainty is not which
> > "universe" you're in; as you say, if both universes exist and you know
> > that, there's no Doomsday argument. But the thing is, you don't know
> > that. Suppose there are N "universes" that all exist. Some X of them
> > have 10^11 people, (N-X) have 10^14, but you don't know what fraction X/N
> > is.
>
> Generally, and conservatively, this is true. For AUH, however, N>>1
> and population size is allowed to vary freely among the universes, so we
> would expect many, many more universes with populations maximally
> exceeding the current population, i.e., as large as possible within constraints
> of cosmic evolution.
That's not true. The population size distribution is determined
by the effective probability distribution for the various histories that
could happen. We don't know what that distribution is.
> > If your number is 5*10^10, this suggests X/N is large: Doomsday.
>
> X/N is not known, as you said. What I understand you to mean is that
> for N=1, 10^11seems far more likely than 10^14, according to the
> Doomsday argument. But the most likely number of people should be 5*10^10,
> in this case.
Your last line doesn't make sense. You are not likely to be the
last person ever born! You are probably around the middle of the pack,
which is the point.
> (Now, the current world population growth rate is ~5 people every 2 seconds.
> So each moment we find ourselves in a less and less likely position in the
> history of the human race.)
Again, the above make no sense.
In general, in a period of exponential growth, would would expect
that growth to reverse within a time constant or so. Of course, we do
have some additional information that modifies that in this case.
- - - - - - -
Jacques Mallah (jqm1584.domain.name.hidden)
Physicist / Many Worlder / Devil's Advocate
"I know what no one else knows" - 'Runaway Train', Soul Asylum
My URL:
http://pages.nyu.edu/~jqm1584/
Received on Sun Jan 02 2000 - 14:39:46 PST