On 29.01.2012 23:06 Russell Standish said the following:
On Sat, Jan 28, 2012 at 09:41:27PM -0800, meekerdb wrote:
On 1/28/2012 3:42 PM, Russell Standish wrote:
On the other hand, if you just gave me the metallic platter from
the hard disk, and did not restrict in any way the technology
used to read and write the data, then in principle, the higher
the temperature, the more information is capable of being encoded
on the disk.


I don't think this is quite right. A higher temperature means that
there are more energy states available.  But the concept of
'temperature' implies that these are occupied in a random way
(according to the micro-canonical ensemble). For us to read and
write data requires that the act of reading or writing a bit moves
the distribution of states in phase space enough that it is
distinguishable from the random fluctuations due to temperature.
So if the medium is hotter, you need to use more energy to read
and write a bit.  This of course runs into the problems you note
below.

Hence the requirement that technology not be fixed. It is a
theoretician's answer :).

So in practice it is often colder systems that allow us to store
more data because then we can use small energy differences to
encode bits.

Absolutely! But at zero kelvin, the information storage capacity of
the device is precisely zero, so cooling only works to a certain
point.


I believe that you have mentioned once that information is negentropy. If yes, could you please comment on that? What negentropy would mean?

In general, I do not understand what does it mean that information at zero Kelvin is zero. Let us take a coin and cool it down. Do you mean that the text on the coin will disappear? Or you mean that no one device can read this text at zero Kelvin?

Evgenii

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