Biomedical Engineering Reference
In-Depth Information
than anything else, especially taking into ac-
count that computers back then were 30 or more
tonne giants and were little more than devices
for rapidly performing mathematical operations.
How could we get a machine to produce a copy
of itself? A command from a human programmer
to “Reproduce!” would be out of the question, as
the machine could only respond “I cannot self-
reproduce because I don't know who I am”. This
approach would be as absurd as if a man gave
his partner a series of bottles and glass flasks
and told her to have a child. In von Neumann's
opinion, any human programmer proposing to
create a dynasty of machines would have to take
the following three simple actions:
of programming its genes, which, in the case of a
human baby, will decide whether it has blonde or
brown hair and whether it will be of an excitable
or calm temperament. In short, DNA and RNA
together carry out all the tasks that the first von
Neumann machine has to perform to create the
second machine of the dynasty. And, therefore,
if we decide to build self-reproductive machines,
there is important biological evidence that von
Neumann came across the right procedure to do
so a long time ago.
But, one might wonder, why would anyone
want to build computers that make copies of them-
selves? The procedure could at best be bothersome.
Suppose that someone went to bed after having
spent the evening working at his computer and,
when he woke up the next day found that there
were two computers instead of one. What would
these regenerating computers be useful for? The
answer is that they will be used at remote sites to
perform difficult and dangerous tasks that people
cannot do easily. Consequently, we have to con-
sider at length the possible location of such places.
What is it that is holding back human biological
development? Why, over thirty-five years after
man first set foot on the moon, is there still no
permanent lunar colony? Over three quarters of a
century have passed since man first managed to
fly and most human beings are still obliged to live
on the surface of the Earth. Why? The astronomer
Tipler (1980), from the University of California
in Berkeley, answered this question very clearly
when stated that it was the delay in computer not
rocket technology that was preventing the human
race from exploring the Galaxy. It is in space, not
on Earth, where the super intelligent self-repro-
ducing machines will pay off, and it is in space
where the long-term future of humanity lies. It is
fascinating to consider how Tipler and others who
have studied the far-off future consider how von
Neumann machines will make it possible, firstly
to colonise the solar system of planets and then the
Milky Way with over 150,000 million suns.
1.
Give the machine a full description of it-
self.
2.
Give the machine a second description of
itself, which would be a machine that has
already received the first description.
3.
Finally, order the machine to create another
machine that is an exact copy of the machine
in the second description and order the first
machine to copy and pass on this final order
to the second machine.
The most remarkable thing about this logical
procedure is that, apart from being simpler than
it may appear, it was von Neumann's view of how
living creatures reproduce. A few years after his
conference, his ideas were confirmed when the
biologists Crick and Watson (1953 (a) and (b))
found the key to genetic code and discovered
the secret of organic reproduction. It was es-
sentially the same as the sequence for machine
reproduction that von Neumann had proposed.
In living beings, deoxyribonucleic acid (DNA)
plays the role of the first machine. The DNA gives
instructions to ribonucleic acid (RNA) to build
proteins; RNA is like DNA's “assistant”. Whereas
the RNA performs the boring task of building
proteins for its parent organisms and offspring,
the DNA plays the brilliant and imaginative role
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