Re: int128_t
Re: int128_t
- Subject: Re: int128_t
- From: Rick Mann <email@hidden>
- Date: Fri, 17 Oct 2008 09:34:55 -0700
On Oct 17, 2008, at 07:42:10, Sherm Pendley wrote:
The availability of 128-bit chips will not magically expand the
world economy by thousands of orders of magnitude. Using 128-bit
ints at that point will be a matter of convenience, not of necessity.
Not exactly analogous, but: The following observation was made about
ZFS (which uses 128-bit ints for everything) (http://en.wikipedia.org/wiki/ZFS#Capacity
):
Project leader Bonwick said, "Populating 128-bit file systems would
exceed the quantum limits of earth-based storage. You couldn't fill a
128-bit storage pool without boiling the oceans."[2] Later he clarified:
Although we'd all like Moore's Law to continue forever, quantum
mechanics imposes some fundamental limits on the computation rate
and information capacity of any physical device. In particular, it
has been shown that 1 kilogram of matter confined to 1 litre of
space can perform at most 1051 operations per second on at most 1031
bits of information.[10] A fully populated 128-bit storage pool
would contain 2128 blocks = 2137 bytes = 2140 bits; therefore the
minimum mass required to hold the bits would be (2140 bits) / (1031
bits/kg) = 136 billion kg. To operate at the 1031 bits/kg limit,
however, the entire mass of the computer must be in the form of pure
energy. By E=mc², the rest energy of 136 billion kg is 1.2x1028 J.
The mass of the oceans is about 1.4x1021 kg. It takes about 4,000 J
to raise the temperature of 1 kg of water by 1 degree Celsius, and
thus about 400,000 J to heat 1 kg of water from freezing to boiling.
The latent heat of vaporization adds another 2 million J/kg. Thus
the energy required to boil the oceans is about 2.4x106 J/kg *
1.4x1021 kg = 3.4x1027 J. Thus, fully populating a 128-bit storage
pool would, literally, require more energy than boiling the oceans.
[11]
--
Rick
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