[107835] in Cypherpunks
Re: CDR: A digital way to filter... (fwd)
daemon@ATHENA.MIT.EDU (Bill Stewart)
Mon Jan 25 05:20:22 1999
Date: Mon, 25 Jan 1999 01:05:03 -0800
To: Jim Choate <ravage@einstein.ssz.com>, cypherpunks@einstein.ssz.com
From: Bill Stewart <bill.stewart@pobox.com>
In-Reply-To: <199901242352.RAA02199@einstein.ssz.com>
Reply-To: Bill Stewart <bill.stewart@pobox.com>
At 05:52 PM 1/24/99 -0600, Jim Choate wrote:
>It's linear in the sense that it takes me n steps to determine if n is
>prime.
Yeah, which is exponential in the length of the number,
which is what matters here.
>So, how many primes registers will we need for 2^1024? ....
>2^1024/ln(1^1024)=2.533E305
>
>How long to count at 1M/s pulse rate:
>1.714E302 s, 5.44E294 yrs.
>
>Whis comes out to 10E305.4 registers each 1024 bits in length. So the total
>number of bits taken up by the registers are:
>
>(10E305.4)(1024)=2.572E308 (ie a 2 with 308 places till the decimal)
...
>Hard? Yes. Expensive? Yes. Can we do it today? Probably not. Is it doable?
>Yes.
Your later message quotes some things from Schneier's table of
how big big numbers are - let's look at a few more.
Atoms in Universe excluding dark matter - 10**77 (2**265)
so assuming one atom per bit, you're about 230 orders of magnitude short,
and even if you get a bit denser, say one bit per quark,
you're still way off.
Now, you *might* consider it doable if you accept the
many-worlds interpretation of quantum physics,
so if you can convince enough other universes to buy in to the deal,
maybe you could pull it off :-)
Thanks!
Bill
Bill Stewart, bill.stewart@pobox.com
PGP Fingerprint D454 E202 CBC8 40BF 3C85 B884 0ABE 4639
