larry@JPL-VLSI.ARPA.UUCP (07/24/86)
I have to start with materialism. What we mean today when we say the word
may have a common core with its use in previous centuries, but the details
are vastly different. Today we recognize not only wind and wave, steam and
steel as physical realities, but also quanta and field effects (and virtual
particles!)--subjects that pre-modern physicists and engineers would
consider downright mystical. And that would have been exactly true--in
their time. But we can precisely define these things now, quantify them,
experiment with and measure them. An even more radical difference is that
information--pattern, form--is now a part of physics, "a metric as important
as time, space, charge, etc."
The ability to quantify and measure pattern and shape has profound implica-
tions for the study of formerly mystical topics such as intelligence. It
means we can develop conservation laws for information, without which you
can't construct an essential ingredient of mathematics, equations. I'm not
implying I know what they are in any detail; people with other qualifica-
tions than mine must provide that. But the shape of the research seems to
be clear; cybernetics and information theory provide the basis.
For instance, there are several links between information and energy.
Higher frequency radiation has more bits per unit time. Mutation is the
result of external energy pushing genes beyond the ability of their binding
energies to maintain a stable structure. The impressing of information on
media (diskettes, molecules, brains) requires energy which can be measured.
Organization of information in structures (indexed or random files,
percepts, concepts) has time/energy trade-offs for different kinds of
accesses.
In a way, the information content of an entity is more important than its
material content. A decade from now it's likely that none of our bodies
will contain EVEN A SINGLE ATOM now in them. Even bones are fluid in
biological organisms; only when we die does matter cease to flow into and
out of us. We are NOT matter, or even energy, in the Antique sense. We are
patterns, standing waves in four (or more) dimensions.
Maintaining these patterns within safe parameters, or learning new safe
parameters, requires that our very molecules input data, store it, process
it--often in a recursive or self-referential or time-dependent fashion--and
act. (RNA is an excellent model for an advanced computer, for instance.)
And we can be thought as a number of layers each with its unique informa-
tion needs: cells, tissue, organs, organisms, tribes.
One feature common to all intelligences, however rudimentary, is the ability
to create and manipulate analogs of the environment and of themselves.
Simulations are much cheaper and safer than experiments. This also gives a
clue as to how will impresses itself on the universe despite its immaterial
nature--because it isn't truly immaterial. Patterns are no more independent
of their matter/energy base than matter can exist without pattern. (That
is, the pattern of binding is what makes the difference between an atom and
a burst of radiant energy.) Because intelligence is a pattern of energy it
can affect matter and through triggering have effects enormously greater
than the triggering stimulus. A whim and a whistle can destroy a city--with
an avalanche.
The point of all this is that life and intelligence are no longer
supernatural--beyond the reach of formalism and experiment.
What is still a mystery to me is consciousness, but the understanding
doesn't seem beyond practical realization. It seems reasonable that con-
sciousness arises as a result of time-binding, recursion, and self-
reference. Perhaps multiple layers of vulnerability and adaptability are
important, too. (Our current robots and computers don't have any of these
and are thus poor candidates for models of intelligent mechanisms, much less
conscious ones. Thus I'd agree with one recent critic of some AI research.)
I can't agree that consciousness is an improper subject for scientific
study. Our inability to observe it directly (in a public as opposed to
subjective way) is shared by many other scientific fields. In fact the most
crucial subjects in the "hard" sciences must be studied indirectly: radia-
tion, atoms, viruses, etc. The difficulty of defining terms shouldn't be a
deterrent either. All developing research shares the same problem as the
underlying ideas change and solidify.
Some people object on emotional grounds. Many of them only succeed in
revealing their own limitations, not those of the rest of us. They are too
emotionally stunted to have the strength of humility; they must somehow be
above nature, superior. And too intellectually crippled to see the magic
and mystery in star-shine and bird flight, in ogive curve and infinitesimals
and the delicious simplicity of an algorithm.
Larry @ jpl-vlsi.arpajc@cdx39.UUCP (08/20/86)
[The following hasn't any obvious AI, but it's interesting enough to pass along. Commonsense reasoning at work. -- KIL] > The ability to quantify and measure ... has profound implications ... > > ... A decade from now it's likely that none of our bodies > will contain EVEN A SINGLE ATOM now in them. Even bones are fluid in > biological organisms; ... OK, let's do some BOTE (Back Of The Envelope) calculations. According to several bio and med texts I've read over the years, a good estimate of the half-life residency of an atom in the soft portions of a mammal's body is 1/2 year; in the bones it is around 2 years. The qualifications are quite obvious and irrelevant here; we are going for order-of-magnitude figures. For those not familiar with the term, "half-life residency" means the time to replace half the original atoms. This doesn't mean that you replace half your soft tissues in 6 months, and the other half in the next six months. What happens is exponential: in one year, 1/4 of the original are left; in 18 months, 1/8 are left, and so on. Ten years is about 5 half-lives for the bones, and 20 for the soft tissues. A human body masses about 50 Kg, give or take a factor of 2. The soft tissues are primarily water (75%) and COH2; we can treat it all as water for estimating the number of atoms. This is about (50Kg) * (1000 KG/g) / (16 g/mole) = 3000 moles, times 6*10^23 gives us about 2*10^26 atoms. The bones are a bit denser (with fewer atoms per gram); the rest is a bit less dense (with more atoms per gram), but it's about right. For order-of-magnitude estimates, we would have roughly 10^26 atoms in each kind of tissue. In 5 half-lives, we would divide this by 2^5 = 32 to get the number of original atoms, giving us about 7*10^25 atoms of the bones left. For the soft tissues, we divide by 2^20 = 4*10^6, giving us about 2 or 3 * 10^20 of the original atoms. Of course, although these are big numbers, they don't amount to much mass, especially for the soft tissues. But they are a lot more than a single atom, even if they are off by an order of magnitude.. Does anyone see any serious errors in these calculations? Remember that these are order-of magnitude estimates; quibbling with anything other than the first significant digit and the exponent is beside the point. The only likely source of error is in the half-life estimate, but the replacement would have to be much faster than a half-year to stand a chance of eliminating every atom in a year. In fact, with the exponential-decay at work here, it is easy to see that it would take about 80 half-lives (2*10^26 = 2^79) to replace the last atom with better than 50% probability. For 10 years, this would mean a half-life residency of about 6 weeks, which may be true for a mouse or a sparrow, but I've never seen any hint that human bodies might replace themselves nearly this fast. In fact, we can get a good upper bound on how fast our atoms could be replaced, as well as a good cross-check on the above rough calculations, by considering how much we eat. A normal human diet is roughly a single Kg of food a day. (The air breathed isn't relevant; very little of the oxygen ends up incorporated into tissues.) In 6 weeks, this would add up to about 50 Kg. So it would require using very nearly all the atoms in our food as replacement atoms to do the job required. This is clearly not feasible; it is almost exactly the upper bound, and the actual figure has to be lower. A factor of 4 lower would give us the above estimate for the soft tissues, which seems feasible. There's one more qualification, but it works in the other direction. The above calculations are based on the assumption that incoming atoms are all 'new'. For people in most urban settings, this is close enough to be treated as true. But consider someone whose sewage goes into a septic tank and whose garbage goes into a compost pile, and whose diet is based on produce of their garden, hen-house, etc. The diet of such people will contain many atoms that have been part of their bodies in previous cycles, especially the C and N atoms, but also many of the O and H atoms. Such people could retain a significantly larger fraction of original atoms after a decade. Please don't take this as a personal attack. I just couldn't resist the combination of the quoted lines, which seemed to be a clear invitation to do some numeric calculations. In fact, if someone has figures good to more places, I'd like to see them.