Entropy in an open universe

John K Clark (johnkc@well.com)
Sat, 29 Nov 1997 09:21:26 -0800 (PST)


>>If Tipler is correct, and I think he probably is, then opening a
>>closed universe, even if it were possible, would be the last thing
>>life would want to do because only a closed universe offers the
>>possibility of immortality.

>Twink <neptune@mars.superlink.net>

Dyson says that life processes could continue indefinitely in a open universe,
but that's not good enough, I'm interested in consciousness and intelligence,
I don't care if digestion continues for eternity or not. Immortality means
experiencing an infinite amount of subjective time, and that means being
able to think an infinite number of thoughts and that doesn't seem like a
realistic possibility in a open universe. In an open universe everything
will keep getting colder and most things will get larger and weaker too.
Life will have to keep adapting to new conditions and it won't be easy.

The components of any machine, including a brain, must keep getting more
distant if it's going to work. The reason is that a heat engine in such a
universe will only be able to exploit very tiny differences in temperature
and that means it will be very inefficient. To get a usable energy output it
would need to be HUGE. With parts that far apart and the finite speed of
light the brain is going to slow way down.

There are more problems, all electromagnetic photons would be of VERY low
energy and so would have to have an enormous wavelength. A simple quarter
wavelength antenna for a billion mile photon, or a trillion light year one,
would need to be astronomical, and then some. A reflector to concentrate the
photons for energy use would be MUCH larger still. Also, in order to
establish reliable communication it's going to take more and more photons of
light to send one bit of information. It won't be easy for one part of a
brain to hit it's target a billion trillion light years away, almost zero
chance if you only send one photon. Also, each photon will be strongly and
increasingly redshifted, to compensate the sender must keep shorting the
wavelength of the photons he uses but this takes energy and you only have a
finite amount of it in a open universe.

Contrast this with a closed universe. Tipler thinks that the universe will be
able to perform an infinite, and not just astronomical, number of calculations
between now and the final singularity at the end of the Big Crunch. With this
much computer power it would be easy to emulate every human being who ever
lived and do it for an infinitely long subjective time. But isn't infinite
computation a fantasy? If the universe has a finite number of particles and
all of them are engaged in computation, isn't that a limit? Perhaps not.
The particles could be performing calculations at a faster and faster speed,
of course you'd need an unlimited supply of energy to do that, but that's
exactly what you'd have at The Big Crunch. Tipler thinks that life will be
able to engineer the Universe so that when it contracts to a mathematical
point, it will do so in a asymmetrical way, so one part of the sky will
always be hotter than another thus you can always run a heat engine.
All life on Earth also gets it's energy from a hot spot in the sky that we
call "the sun", the Omega point would also have a hot spot, but the
difference is it will keep getting hotter without limit, in other words
infinite energy.

You'd also need a way for the parts of the computer to communicate with the
other parts at a ever increasing speed, you can't move faster than light, so
the only way to do this is to make the distance between the parts shorter.
This is also exactly what you'd have at The Big Crunch.

And You'd need infinite memory. Tipler found a way that the Universe could
hold an infinite amount of information, he wants to store information as
standing waves and use the entire universe as a wave guide. As the universe
shrinks toward The Big Crunch the amount of time needed to access this
information is reduced too, but so is the amount of energy needed to store a
bit of information, because you need to keep making your information storing
photons at a shorter and shorter wavelength and that takes energy. If you
only have a finite amount of energy this would be a fatal problem, but if the
universe shrinks to a geometric point then the amount of gravitational sheer
energy in the Universe would diverge to infinity, and as I said if the
collapse is not symmetrical then the energy is usable.

There is a finite amount of time to the Big Crunch, but Tipler says that a
beam of light could circle the entire universe an infinite (and not just very
large) number of times before then, because the universe will keep getting
smaller without limit. In this way a finite amount of matter in a finite
amount of time could produce a infinite number of calculations and so
generate a infinite subjective time. To put it another way, the idea is to
trade energy for subjective time, we have infinite energy so we have infinite
subjective time.

As for Entropy, it's only a problem if it ever stops increasing as it would
in the heat death of an open universe, in a closed universe the Entropy never
stops increasing and the heat never stops increasing. Of course all of this
is irrelevant if the universe is open, and it's starting to look like it may
be, we should know in a few years. Tipler also made a number of testable
predictions, I'll get into that if you're interested.

John K Clark johnkc@well.com

Version: 2.6.i