X-Message-Number: 1940
From: Ralph Merkle <>
Subject: Glass Transition Temperature Storage
Date: Wed, 10 Mar 1993 18:09:33 PST

Storage at or near the glass transition temperature should indeed
be able to reduce or eliminate the kinds of fracture damage
that occurs today with storage at the temperature of liquid
nitrogen.

However, the kind of fractures that occur in a glassy substance
should result in little or no loss of structural or ultrastructural
information.  As a consequence, if the objective is to provide
the highest possible probability of information theoretic survival,
then storage at or near the glass transition temperature offers little
if any benefit over storage at the temperature of liquid nitrogen.

Given the damage done by current suspension methods (and the likely
requirement for a mature nanotechnology to achieve a satisfactory cure),
the benefits of storage at the glass transition temperature are marginal.

If and when "fully reversible" (e.g., reversible using today's technology)
brain cryopreservation is achieved, storage near the glass transition
temperature might offer the potential benefit of a cure without the
need for a mature nanotechnology.

In the meantime, storage in liquid nitrogen is safe, simple, reliable, and
cheap.  Any competing proposal for storage near the glass transition
temperature must have these desirable properties for serious consideration,
and a relatively conservative stance should be taken towards its adoption.

   Cheers!
     Ralph C. Merkle

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