George Levy wrote:
> In a message dated 09/14/2000 9:05:44 AM Pacific Daylight Time,
> smitra.domain.name.hidden writes:
>
> > Stewart, on the other hand, considers the RAC, whose clock accelerates
> > exponentially fast, with pulses separated by intervals of 1/2, 1/4, 1/8
...
> > seconds. So the RAC can cram an infinite number of computational steps
into
> a
> > single second.
>
> It may be impossible to construct such a machine in our universe, but can
we
> achieve the same results by slowing down the consciousness of the observer
> observing a conventional computer? In other words, each observer's clock
> cycle (assuming a computer model for the observer) would double in
duration
> in relation to the computer clock. Could there be such an observer in our
> universe? I suspect that there can't be because the construction of the
> observer's clock woud require smaller and smaller energy packets in the
> presence of constant background noise.
>
> George Levy
>
>
The observer also has to survive ``forever´´. This problem is investigated
in the context of eternal inflation models in the paper:
http://xxx.lanl.gov/abs/astro-ph/9909143
ABSTRACT:
``We discuss the large-scale structure of the universe in inflationary
cosmology and the implications that it may have for the long-term future of
civilizations. Although each civilization is doomed to perish, it may be
possible to transmit its accumulated knowledge to future civilizations. We
consider several scenarios of this sort. If the cosmological constant is
positive, it eventually dominates the universe and bubbles of inflationary
phase begin to nucleate at a constant rate. Thermalized regions inside these
inflating bubbles will give rise to new galaxies and civilizations. It is
possible in principle to send a message to one of them. It might even be
possible to send a device whose purpose is to recreate an approximation of
the original civilization in the new region. However, the message or device
will almost certainly be intercepted by black holes, which nucleate at a
much higher rate than inflating bubbles. Formation of new inflating regions
can also be triggered by gravitational collapse, but again the probability
is low, and the number of attempts required for a positive outcome is
enormous. The probability can be higher if the energy scale of inflation is
closer to the Planck scale, but a high energy scale produces a tight bound
on the amount of information that can be transmitted. One can try to avoid
quantum tunneling altogether, but this requires a violation of quantum
inequalities which constrain the magnitude of negative energy densities.
However, the limits of validity of quantum inequalities are not clear, and
future research may show that the required violation is in fact possible.
Therein lies the hope for the future of civilizations.´´
You can imagine that a device could be made such that the observer is
slowing down by a factor of two compared to the previous generation. So,
maybe the quantum inequalities are a manifestation of the limitations of the
universal Turing machine.
Saibal
Received on Thu Sep 14 2000 - 13:14:24 PDT