Re: Solo Brain: was[nanotech] the core issue

From: Anders Sandberg (
Date: Mon Apr 03 2000 - 17:48:30 MDT

"Eliezer S. Yudkowsky" <> writes:

> Anders Sandberg wrote:
> >
> > When I was younger I actually thought the road to posthumanity was
> > removing the brain, keeping it alive and connecting it to intelligence
> > amplification and telepresence systems. This was largely based on the
> > erroneous idea that the brain itself doesn't age, so this would also
> > be immortality. Then I read Hans Moravec and became an uploader... :-)
> Uploading isn't enough, either. Do you think the mind doesn't age?

The mind certainly ages too, but not in the directly entropic manner
as a biological brain does - losing receptors, accumulating junk
proteins, possibly going Parkinsonian and so on.
> I would be astonished to find that an unmodified human mind could last a
> mere thousand years (subjective) before crystallizing into senility,
> overloading memory space, losing associational mechanisms, or just plain
> falling apart at the seams.

The real problem here is the plasticity-stability dilemma of memory
(incidentally very close to my research area - what a coincidence!
:-). If you have a plastic brain it will learn well and adapt over
time, but old information will be lost - after long enough time you
will not be you. If it becomes less plastic (as our brains are
currently apparently doing) it will eventually become overloaded or
static and stop working well.

It is not obvious how mental plasticity is changed psychologically and
biologically; there is definitely a biological component uploading can
fairly easily fix (and then you can set your own baseline plasticity),
but the psychological aspect is less understood. Most likely there are
mental requirements for indefinite lifespans, and they might be quite
strict. Just being uploaded is not enough for immortality, that is
likely sure.

There is really no way of avoiding eventual "death forward" since even
if you keep your mind flexible and healthy it will have to change over
time and will eventually have become so different that little of the
original remains.

If your "memory/self size" does not grow you will eventually get
caught in a loop or have to forget stuff to survive (not necessarily
everything, you could always keep an unchanging core and change
everything else). If you grow, then the original self will eventually
become arbitrarily small compared to the rest of you. The slowest rate
that does not lead to recurrence in the long run is logarithmical in
subjective time (imagine a counter counting up).

Anders Sandberg                                      Towards Ascension!                  
GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y

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