From: Jim choate <ravage@bga.com>
Date: Thu, 31 Mar 94 05:54:56 PST
To: hfinney@shell.portal.com (Hal)
Subject: Re: Bekenstein Bound (was: Crypto and new computing strategies)
In-Reply-To: <199403310605.WAA22633@jobe.shell.portal.com>
Message-ID: <199403311354.AA01893@zoom.bga.com>
MIME-Version: 1.0
Content-Type: text


> 
> The Deutsch paper I quoted before was where I first heard of the Bekenstein
> Bound which Eric Hughes mentioned.  According to Deutsch:
> 
> "If the theory of the thermodynamics of black holes is trustworthy, no
> system enclosed by a surface with an appropriately defined area A can have
> more than a finite number
> 
>         N(A) = exp(A c^3 / 4 hbar G)
> 
> of distinguishable accessible states (hbar is the Planck reduced constant,
> G is the gravitational constant, and c is the speed of light.)"
> 
> The reference he gives is:
> 
> Bekenstein, J.D. 1981 Phys Rev D v23, p287
> 
> For those with calculators,  c is approximately 3.00*10^10 cm/s, G is
> 6.67*10^-8 cm^3/g s^2, and hbar is 1.05*10^-27 g cm^2/s.  N comes out
> to be pretty darn big by our standards!
> 
> Hal
> 
> 
The problem I see with this is that there is no connection between a black holes
mass and surface area (it doesn't have one). In reference to the 'A' in the    
above, is it the event horizon? A funny thing about black holes is that as the
mass increases the event horizon gets larger not smaller (ie gravitational
contraction).