> Date: Sat, 2 Apr 1994 17:53 EST
> From: [email protected] (Marc Andreessen)
>
> John C. Mallery writes:
> > pdi://authority-name//4-digit-year/2-digit-month/2-digit-day/document-of-the-day-number.format.version
>
> Yeah, but what happens when the year 9999 arrives??? Huh? Huh?
>
> Cheekily,
> Marc
> Wrap around.
Four digits may not be enough, but it does seem likely
that we can use a fixed size field here. Let me explain.
I understand that one of the hottest topics in modern
cosmology today is the debate over just how much dark
matter is out there in the universe. What cosmologists want
to know is whether there is enough mass to eventually
reverse the current expansion of the universe ("enough"
being the layman's term for the needed amount. The
correct cosmologists's technical term for this amount is
"billions and billions").
[* And of course as well-informed readers will know,
current thinking in this field attributes the
measureable expansion of the universe to the initial
"Big Bang" ("grand explosion" in French, or "grosse
kaboum" in German) which is believed to have occured at
the birth of the universe. This expansion was first
identified by the famous astronomer William Hubble, who
is best know for his poor eyesight but who did at least
have a keen sense of colour perception. For example, he
was the first to identify the famous "Hubble Red Shift"
in the early part of this century while helping his
wife choose an outfit for a weekend outing. But I
digress... *]
Anyways, assuming there is sufficient mass to halt the
expansion of the universe the most likely scenario is that
the universe will eventually collapse back onto itself.
This obviously puts an outer limit on the amount of time we
need to allow for in the above URN scheme (and thus the
number of digits we need to accomodate). (Of course, it
also puts paid to any plans you might have had to arrange
a really effective long term backup strategy for your
site, but hey, who said systems administration would be
easy?)
Another possibility is that there is _not_ enough dark
matter to halt expansion of the universe. Here we would
probably be saved by the n'th law of Thermodynamics
("n'th" is used to indicate that I can't remember exactly
which one it is I mean here, so you have to figure it out
yourself). Basically, this law states that all closed
systems tend to entropy, which is a long-winded way of
telling us (so I'm told by all those really depressing
stories I keep reading in Discover magazine) that the
universe will eventually all end up spread out as a cold
and lifeless collection of widely spread out nothingness.
Brrrr...
Given this scenario, at some point there wouldn't be enough
energy left to power your machine, so there wouldn't be
any point in you actually storing any more URNs anyways.
Again, we don't know how long this would be yet, but since
we started with a finite amount of matter and it's
expanding (and cooling) at a finite rate, we've a finite
amount of time before you might as well unplug the machine
and go home.
Assuming we can calculate how long it takes to get
everything to cool down enough we can thus still put an
upper bound on the number of digits we need to allow for
(and I understand that now the superconducting
supercollider's been cancelled there are thousands of
out-of-work physicists who'd love to help with the
calculations on this in exchange for having their name on
the resulting paper. As the supercollider's budget showed,
these guys really love big numbers but I still think we're
talking a finite number of digits here).
The only possible wrinkle we can't rule out is if there is
_exactly_ enough dark matter out there to halt expansion
of the universe at some still useful point on the
thermodynamic power curve, but _not_ enough to cause
everything to collapse back down onto itself. I know this
sounds unlikely, but who'd have predicted the success of
MS-DOS ten years ago? Given this existance proof of a
capricious and vengeful God, we can't rule this third
possibility out.
Still, covering two out of the three possible bases in a
version 1.0 URN still seems better than any of the other
proposals we've got kicking around right now. Besides, I
think we'll be proposing something that would last a bit
longer than the address space used in the initial version
of IP. And if turns out that MS-DOS wasn't a one-off
mistake, we can plan on fixing our problem using the same
technique they come up with for IPng.
- peterd
-- ------------------------------------------------------------------------------ My proposal for funding the Internet is pretty simple. I vote we institute an "Information Superhighway" tax, the proceeds of which will be used to fund network infrastructure. The way this would work is simple - every time someone uses the words "Information Superhighway" or any of its derivatives we strike them with a sharp object and make them pay a $10 fee (of course, the sharp object is not actually needed to make this scheme work, it's just in there because it seems an appropriate thing to do...) ------------------------------------------------------------------------------