The Best of Creative Computing Volume 2 (published 1977)
Communication Across The Universe (constructing intelligible pictograms)
One other carrier of information might exist in the form of the faster than
light tachyons.
***
with naturally occurring interstellar debris increases dramatically with
increasing speed, so it is not clear how well high speed spacecraft could
survive prolonged interstellar voyages.
Electromagnetic signals, or signals employing gravitational waves and neutrinos
all travel at the speed of light. At that speed a message can reach the nearest
stars in a matter of years, the center of our Galaxy in thirty thousand years,
and the nearest galaxies in some millions of years. Two way conversations would
have to be correspondingly slow. Just now electromagnetic waves may look like
the best bet because we do not yet know how to receive or transmit gravitational
waves, and the transmission and reception of neutrinos is discouragingly
inefficient. But all that may change.
One other carrier of information might exist in the form of the faster than
light tachyons. Tachyons are hypothetical particles which may very well not
exist at all. We just don't yet know. However, if they do exist, they would be
priority choice for urgent messages. They could be transmitted at such high
speeds that two-way conversation might be practical in some instances. Tachyons,
if they can be generated, would take advantage of a loophole in the laws of
relativity. Einstein's special theory states that no particles can be
accelerated up to or beyond the speed of light. However, it does not state that
particles can't be generated directly at these high velocities. Just as two
colliding photons can give rise to a pair of particles such as an electron and a
positron or a proton and an antiproton, both travelling at velocities well below
the speed of light, so also we can imagine two photons colliding and giving rise
to a pair of tachyons. We do not yet know how to detect these entities, but as
long as we remain uncertain about their existence, we will be ignorant of what
might well be the most promising channel for interstellar and intergalactic
messages.
***
We now turn to the language to be used. Two ideas have been widely discussed in
this context. The first involves pictograms - simple pictures that might be
easily understood. The second concerns artificial languages that are self
explanatory.
This second approach is particularly interesting. The most extensively
developed language of this kind is Lincos developed by the mathematician Hans
Freduenthal at the University of Utrecht. In essence, he starts out with a list
of symbols representing one dot, two dots, three dots, .=1, ..=2, ...=3, and so
on. He then lists examples of addition. Essentially
1 + 1 = 2
1 + 2 = 3
2 + 1 = 3
1 + 1 + 1 =3
and so on. This defines not only mathematical relations, but also the concept
of equality that is a common part of our social thinking. Symbols like < and >
are similarly defined by lists of numerical examples and eventually work their
way into such concepts as greatness, prominence, and so on.
In principle such a language can go on to physics, for instance, by listing the
relative masses of all atoms and nuclei known to be stable. Every advanced
civilization will know the values of these masses which bear a nearly – but
not quite - integer relationship.
And once the elements are defined a further listing can show elementary chemical
reactions and structures including those that are fundamental to our existence -
metabolic processes and genetic structure. Beyond this stage a message can
become encyclopedic. For, it is really the fundamental structure of the
language that is most difficult to establish. Once that is accomplished, more
sophisticated concepts can readily be added in any quantity.
The problem of constructing intelligible pictograms is somewhat different. Such
pictures consist of light and dark squares arrayed very much like a television
picture. There are mn elements - where m and n both are prime numbers. With
this choice of prime numbers there are only two ways that a rectangular array -
picture - can be obtained: a picture with n rows and m columns, or one with m
rows and n columns. If m = n the picture is square and unique except for a
left-to-right, up-down ambiguity.
Proponents of pictograms often do include some elementary arithmetic and
chemical concepts in their pictures, but they rapidly go on to show more
sophisticated ideas, a picture of man or a sketch of the solar system.
Whether such pictures are intuitively obvious is not really clear. Our own
intuition is so
***
The first reception of extraterrestrial messages no doubt will involve great
difficulties and major technical advances. However, once this initial barrier
is overcome a whole new social era could begin.
***
strongly conditioned that such messages are likely to be quite fundamentally
prejudiced to the extent of being incomprehensible to an alien civilization.
Ultimately the pictograms should be subject to exactly the same need for logical
development as any other language, and I imagine a properly designed
interstellar message is likely to contain both a preliminary developmental
chapter that defines the language, as well as a message that may be partly in
the form of words, and partly illustrated by pictograms.
***
The final question to be considered here is whom to address. Or whom to expect
to transmit.
If we believe that life can only exist on planets, then we might first transmit
messages to the nearest known planetary systems or search for messages emanating
from these nearest neighbors. Such messages might consist of individual symbols
(letters, numbers) each transmitted for a period lasting anywhere from seconds
to hours.
On the other hand if, as Frank Drake has pointed out, some forms of life could
exist on a neutron star where temperatures are far higher than on Earth,
metabolic rates could be speeded up a million-fold. Such a civilization might
then transmit messages at a rate of a million symbols a second. The problems of
transmitting and receiving at these speeds would not necessarily be more
difficult for us, but we would have to be aware of the great range of
possibilities. Not only would we have to worry about the language to use, the
contents to be transmitted and the means of transmitting, we even would have
uncertainties about how "fast to talk."
The first reception of extraterrestrial messages no doubt will involve great
difficulties and major technical advances. However, once this initial barrier
is overcome a whole new social era could begin.
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