Re: [XPOST] A unique number for every "person" - can it be done?
From: Dave Rusin (rusin_at_vesuvius.math.niu.edu)
Date: 02/28/05
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Date: 27 Feb 2005 23:45:09 GMT
In article <GrrUd.286$q3.19856@news7.onvoy.net>,
gerard46 <gerard46@rrt.net> wrote:
>I once read somewhere that as of the dawn of our history (starting from
>40,000 years ago), that there were "only" a few millions of people who
>had lived (and that includes baby-deaths, as I recall). There was a
>graph showing the total living population of the earth, as well as the
>total of people who had lived, up to any point (year).
>
>If anyone knows of a website that shows this graph or a version of it,
>it would be nice to view again. There weren't that many (dead) people
>on earth. Of course, "many" is a subjective term, but not beyond
>grasping (understanding).
It is a consequence of exponential growth of population that the total
number who have ever lived will always be a fixed multiple of the
then-current population.
But certainly there is an upper bound to the number of humans who can
exist at once as long as human beings are disjoint subsets of the
universe's elementary particles. What does the universe consist of,
maybe 50 or more orders of magnitude more matter than a human being?
Then you could only have at most 10^50 humans at a time.
And how long will the universe last? It's already maybe 10^10 years old,
and although there are different proposed models for how it will end,
they all project an ending in less than 10^11 more years. Even if the
human lifespan is somehow reduced to mere seconds, that only allows
for a re-constituting of the matter of the universe into new humans
at most 10^7 times per year, so that there cannot be more than 10^18
generations of humans.
Combining these guesstimates puts an upper bound well short of 10^68
for the number of humans there will ever be, and the hypotheses necessary
to get anywhere close to that are frankly ridiculous. If every person
were assigned a 100-digit number there would never, ever be need to
have duplicate numbers.
Things are more interesting when numbers are also to be assigned to
groups of individuals. The power-set of the set of humans already
has cardinality larger than 2^(6 billion), and the kind of reasoning
above allows for say 2^(10^20) or 2^(10^50) subsets of all humans.
If we need to number them all, we will need IDs for them which will
obviously be billions or trillions or ... digits long, and that's
_assuming_ that an association of humans is uniquely determined by
its membership. (It could well be that Jack the Ripper, Mahatma Gandhi,
and my first great^5-grandson are the sole members of two or more
clubs, which then should have separate IDs.
Yours Sincerely,
265616025911851103824867590481468036207394504121788161910825597879541845282601946331090882441377
- Next message: Bryan Olson: "Re: Thou shalt have no other gods before the ANSI C standard"
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