Additional droguli videos (updated 6 Apr 2021)
Tim Taylor has made available superior videos on droguli with audio commentary
on this web page advertising his new book:
https://www.tim-taylor.com/selfrepbook/
Rise of the Self-Replicators: Early Visions of Machines, AI and Robots That Can
Reproduce and Evolve,
by Tim Taylor and Alan Dorin
Published by Springer, 31 July 2020, DOI: 10.1007/978-3-030-48234-3
Search down the page to the section headed:
Additional Materials
Films of Lionel Penrose's explorations of physical self-replication
This is followed immediately by two videos
Automatic Mechanical Self Replication (Part 1, 1958)
https://youtu.be/12HfFvjSAHc
Automatic Mechanical Self Replication (Part 2, 1961)
https://youtu.be/hQ6T_TY3JA4
In 1959, Lionel Penrose wrote in New Biology, "I had difficulty in finding a
suitable name for the activated complexes produced in [certain] experiments. On
showing one of them to Professor A. J. Ayer, I inquired whether it perhaps might
be a 'drogulus' ... He replied that it was undoubtedly a 'drogulus'."
It seems that in a radio broadcast some years earlier, Ayer, the philosopher,
had talked about a drogulus that was invisible, intangible, and had no effects,
in order to pour scorn on certain philosophical (theological?) theories.
So perhaps he was pleased to be able transfer the label from something utterly
useless to something of great interest.
Note added 21 Jul 2015
Some time after writing the above I tried another google search and found a
reference to this very short note:
L.S. Penrose, R. Penrose, "A self-reproducing analogue,", in
Nature 179(8 June 1957):1183
http://www.nature.com/nature/journal/v179/n4571/abs/1791183a0.html
The mechanism described in that paper is simpler than the mechanism I recall
being presented by Lionel Penrose in his lecture on droguli, which must have
been a few years later than 1957 (the year I arrived in Oxford as a mathematics
student, about two years before I switched to philosophy). The Nature note does
not include either "drogulus" or "droguli". An earlier version of this paper
attributed the later work to Lionel and Roger Penrose, because they jointly
authored the Nature note. However, another member of the family may have been
involved in the later work on droguli shown in the videos made available by
Rodney Brooks.
Energy stores
If some of the temporarily stable structures are also able to store energy that
they can release under conditions that are partly controlled by parts of those
structures then some complex persistent structures may begin to manipulate other
complex structures -- assembling and disassembling them.
For example, if a structure has two arms pressed together by an elastic
connector and a temporary gust of force moves the arms apart just as something
comes between them, then the two arms may come together so as to grip the new
object, forming a stable triad, in which elastic energy is stored, because the
two arms have not returned to their original distance apart: they are held apart
by a new strut.
In many such cases the energy required to undo the new structure may be greater
than the energy required to create it, because of asymmetries in the mechanism.
This is the basis of the common ratchet mechanism: the Penrose reproducing
droguli essentially made use of ratchets, and an external
(random) source of energy provided by someone shaking the tray.
In a subsequent state something new could come between the protruding ends of
the two arms.
If at the same time yet another object causes the strut to break or fold,
it will cease to hold the two arms apart, and they will come together and press
on the new object, and the force applied to that object could trigger some other
reaction, creating yet another new object, possibly more complex than the
preceding objects.
This very abstract scenario in which structured objects affected by random
forces interact so as to create new, more complex, relatively stable structured
objects may appear to violate the 2nd law of thermodynamics. But the violation
is not real because we are not describing a "closed" system.
Speaking loosely, we can say that external sources of energy produce
random changes, but the already formed structures constrain and direct the
consequences of those changes in non-random ways. In particular, new random
bursts of energy may suffice to cause previously built structures to overcome an
obstacle to bonding and forming a new more complex relatively stable structure.
Moreover if some of the stable chemical structures store energy that can be
released only in certain ways (e.g. the electrical energy of a laptop battery
can only be released under certain conditions, e.g. when a circuit is closed),
then chemical keys (catalysts) may in some circumstances trigger complex
constrained non-random processes, like the processes of formation of an embryo
from a fertilized egg, or the growth of a plant from a seed, triggered by
temperature, moisture and light.
Propagation of constraints across scales
Of course, what sorts of new large objects can be produced will depend on the
shapes and other physical properties of the original small components, and the
presence of non-uniform external forces that provide new (e.g. kinetic)
energy that can be stored (e.g. as potential, elastic or chemical energy).
The types of
shapes that can be assembled by applying forces to lego bricks and the types
that can be assembled from meccano components, including nuts, bolts, girders
with holes, angle-girders, plates, flanges, rods, cranks, wheels, string, clips,
etc. are very different, though both types are of unbounded complexity, in
principle.
The types that can be formed by assembling molecules will be even more varied
and will have far more complex potential behaviours fuelled by chemical energy
and controlled by molecular structures and their constrained relative movements.
Extending Tibor Ganti's analysis of requirements for life
The ideas presented here build on the work by
Tibor Ganti
(2003) on minimal conditions for life to form in something like a
chemical soup. See also Ganti's Chemoton theory:
http://en.wikipedia.org/wiki/Chemoton)
As I understand him Ganti was trying to identify a class of
minimal physical configurations,
consistent with what we know about the physical universe, that are
capable of supporting the key functions of life: self maintenance (including
holding parts together), growth, repair and reproduction.
In contrast, I am trying to identify the minimal physical
properties of a universe (or a planet!) in which life forms as diverse
and complex as those found on Earth (so far) can evolve by natural selection (or
even by some other means, including future types of laboratory synthesis). For
this we need to explain the possibility of an enormous variety of biological
phenomena, on many different scales, from microbes to elephants and blue whales,
with many different information-processing capabilities, in addition to those
required for storage of information in molecular structures that can control
subsequent chemical processes, such as assembly of new structures from old.
There's no need to limit the requirement to evolution on our planet. There may
be other parts of the universe in which very different, and even far more
complex forms of life have evolved, or could evolve, using the same basic
construction kit. (Compare the diversity of human languages implicitly supported
by the human genome.)
It follows that these conditions require not only the ability to support Ganti's
chemical configuration, but also the generative (combinatorial) power to support
arbitrarily(?) large and complex life forms, with arbitrarily complex
controlled, useful, behaviours.
Those two conditions are importantly different: specifying a structure for a
complex animal body, specifies a possible variety of processes in which parts
change their relations to each other and to things in the environment, but
leaves open which of those processes will occur, i.e. what sorts of movements it
will make in various situations. That requires additional information and
typically that information is not static, but can change with learning. So in
addition to the basic building blocks of organisms being able to support an
enormous variety of physical structures they also need to be capable of
representing (or encoding) an even larger variety of types of process in which
those physical structures interact with other things.
Furthermore, since the repertoire of processes for many organisms will not be
fixed, an additional repertoire of forms of representation for strategies or
patterns of alteration by learning or instantiation of generic patterns via
inheritance mechanisms will be needed. In some cases these will make use of
virtual machines, as argued in
http://www.cs.bham.ac.uk/research/projects/cogaff/misc/vm-functionalism.html
All of this implies that the mechanisms supplied by the physical universe need
to be able to support layers upon layers of complexity of structure, some of it
physical structure but probably a lot more of it "invisibly" representing or
encoding (in different ways) information about structures, processes, and both
physical and abstract machinery. The genius of pioneers such as Frege, Church,
Post, Turing and others in the recent past is that they were able to specify
abstract machines that were physically implementable, and which had relatively
simple structures but were capable of generating enormously varied structures
and processes, including everything we now find on the internet and much
besides.
But they all depended on the assembly of the machines and the lowest
level control functions to be determined by human designers (and later on
machines programmed by human designers, or machines programmed by machines
programmed .... by human designers).
In contrast the physical universe at the time of the formation of this planet
had the capability not only to combine components to provide all the physical
structures and all the information structures now found on this planet, but also
to do it entirely unaided, and without any plan or guidance from would-be users,
until evolution had produced animals that could take decisions about breeding
and genetic engineering.
One of the things we have learnt from AI research (and other kinds) is that it
is possible to specify a system whose combinatorial generative powers have the
ability to produce solutions to complex problems, but lack the ability to find
the solutions without using combinatorial search processes that are too time
consuming (or space consuming) to fit into the physical universe. So another
requirement was for the physical universe, at the time the earth formed, to have
the ability to evolve mechanisms that would constrain such searches, e.g. using
symmetry and other properties of search spaces, so as to allow a huge variety of
wonderful solutions to a huge variety of horrendously complex design problems to
be found, in a mere four and a half billion years on a medium sized planet"
I suspect nobody knows yet how the basic laws and materials of physics do that.
The meta-morphogenesis project may eventually provide answers.
It could turn out that any system that can meet Ganti's conditions can also meet
additional conditions for supporting arbitrarily complex life forms, but that's
not obvious: there could be a universe, or even a location in this universe,
where the types of materials available meet Ganti's conditions, but can support
only fairly simple life forms -- e.g. because they do not enable the
construction and maintenance of multi-cellular organisms with abilities to act
on large objects in the environment.
I am not aware of any intrinsic physical limit to possible lengths
of polymers, which provide one example of a form of chemical combination that
seems to support ever increasing size. There are probably many others, including
structures that are more heterogeneous than polymers. It seems intuitively that
the variety of ways in which chemical structures can combine to form larger
structures has no intrinsic upper bound.
Moreover, as the sizes of molecules increase so do their diversity of
composition, physical properties, and chemical properties. This suggests that
chemistry also provides a basis for arbitrarily rich and complex information
stores.
So there may be no limit to the sizes and complexity of behaviours of possible
organisms, apart from limits that come from problems of size, such as
gravitational collapse, and problems of communication across large distances,
required for coordination of an organism's behaviour, or lack of access to an
external supply of sufficient nutrients, or even problems of waste disposal for
a very large organism.
Comparison with Turing machinery
There is also no theoretical limit to the size of the symbol structure that can
grow on the tape of a turing machine. However the larger the structure the more
time will be required for interactions between parts added at different stages,
because of the linear nature of the tape.
In computers using the von Neumann architecture,
the use of bit patterns to store addresses of locations in a large memory can
make access and updates very fast, but the "word length" (number of bits in an
address) will limit the size of memory that each machine can handle, though
combining different memory structures (e.g. core memory and hard drives or
tapes) can allow limits to be overcome without redesigning the core machine, at
the cost of slowing things down.
In contrast,
the use of 3-D chemical structures in 3-D space to store information
seems to allow arbitrarily large information stores (until something like
gravitational collapse becomes a problem). Moreover if the molecules used can be
bent, twisted and folded, then it is possible for items added at different
stages to be brought close enough to each other to interact, possibly using
"bridging" molecules to link items.
There will still be constraints, however: a
newly added substructure cannot be brought close to two pre-existing structures
that are rigidly held very far apart for some reason. Nevertheless being
embedded in a 3-D geometric space rather than a linear space of concatenated bit
strings allows a rich variety of chemically constructed communication channels
that can be used in parallel, as illustrated by neural networks.
I suspect that we don't yet understand more than a tiny subset of the varieties
of chemical information processing used in life of earth. For now, all I am
trying to do is emphasise the variety of types and structures of information
stores and information-processing systems made possible in principle by
chemistry (which in turn depends on quantum physics). Natural selection on earth
may have made use of more aspects of chemical information processing than we
have so far discovered.
Possible further developments
This discussion is merely a very rough, abstract, partial answer to: how is it
possible for random processes to produce some large, complex objects with
complex behaviours, starting from very much smaller elements affected by
randomly varying forces. An important additional step is required before this
has any chance of becoming an explanation of the origins of complex living
organisms, namely the identification of physical structures that can encode
acquired information that can later be used, e.g. information about where things
are, information about how to do something or prevent something, information
about how to create a new instance of something, and so on.
Available evidence suggests that chemistry provides the required initial basis,
with sub-atomic components capable of being rearranged in different sorts of
molecules with different physical and chemical properties, including different
combinatorial properties.
Later on, forms of information storage and mechanisms for manipulating and using
the stored information come out of evolutionary processes based on that
chemistry.
Eventually this leads to evolution of chemistry-based mechanisms able to
construct neural systems. Over time (after further evolution) the resulting
brains get larger, more complex, supporting more varied types of
information-processing. Much later on brains become able to support virtual
machines in which virtual symbolic structures such as sentences, equations,
maps, abstract diagrams and many information structures that nobody understands
yet, come to be used. (Some requirements for virtual machinery are mentioned
briefly below.
Later still, machines produced by machines with brains instead use transistors,
wires, and other devices to build more and more complex information-processing
machines including physical machines that can support more and more complex
varieties of virtual machinery..
For more on virtual machinery including the causal powers of interacting
virtual machines, see
At present, very little is known about how brains support virtual machinery as
they clearly do while you think about what you read, plan a move in chess,
try to remember what you had for lunch yesterday, wonder why things
look a little blurred to you if you partially close your eyes, etc.....
This is a long term project. For now, I merely wanted to say that provided that
the system starts from components of the right sort, which have the ability to
be assembled in an enormously rich variety of ways, varying scales from
sub-microscopic to Giant Redwood trees, some of which have the ability to store
energy acquired from the environment then later release it, and some of which
have the ability to encode information that can later be used (through some
decoding, or interpreting, mechanism), then, in principle, random rearrangements
of those components, triggered by external or internal forces, could, from time
to time, produce entities with properties of biological organisms. So perhaps 4
billion years on an earth-sized planet is plenty of time for processes of
agglomeration constrained by previously built structures, to produce ecosystems
as diverse as those on earth.
This is totally different from the false claim that a tornado could assemble a
Boeing 747 from a junk-yard containing enough parts.
Some more detailed requirements for the process to get started are in
Tibor Ganti's book on how chemistry can support life
Ganti (2003).
Newtonian mechanics would not suffice
A universe made of Newtonian point-masses would not have the required
properties. I don't know whether Newton, or his contemporaries, understood
these inadequacies of the so-called Newtonian world view.
Newton was very interested in chemistry/alchemy, asked some deep questions and
formulated some interesting hypotheses, as reported in
http://www.chemistryexplained.com/Ne-Nu/Newton-Isaac.html
In particular, he wrote:
"Have not the small Particles of Bodies certain Powers, Virtues, or Forces by
which they act at a distance, not only upon the Rays of Light for reflecting,
refracting and inflecting them, but also upon one another for producing a great
part of the Phaenomena of Nature? For it's well know that Bodies act one upon
another by the Attractions of Gravity, Magnetism and Electricity; and these
Instances shew the Tenor and Course of Nature, and make it not improbable but
that there may be more attractive Powers than these. For Nature is very
consonant and conformable to her self."
(Quoted on various internet sites, e.g.
http://galileo.phys.virginia.edu/classes/252/atoms.html)
So Newton's thinking was not a long way from the ideas presented here!
A universe made of chemical components as diverse in their shapes and behaviours
as the chemistry on this planet can in principle support the assembly of larger
and larger structures with more and more complex and varied behaviours.
The work
of Ganti (2003) on how chemistry can
support life, at least in its simplest forms is very relevant here.
The chemical
properties of atoms make them very different from the components of meccano
sets, tinker toys and other construction kits.
With the appropriate components, blind external
forces could assemble very complex and interesting structures without violating
any physical laws.
The addition of abilities of some of those structures to
include information about how to produce copies of themselves allows designs to
compete with one another and natural selection processes can emerge where there
is competition for resources or space and relative success in the competition
depends on reproducible design features.
Competition is not essential for evolution
But competition is not necessary for evolution to occur.
Even in times, and places, of plenty
where competition is not needed, peaceful co-existence can lead to new alliances
allowing new achievements, e.g. better defences against extremes of temperature,
or storms. New forms of symbiosis may be the result in some cases. In that sense
natural selection can be opportunistic without being competitive.
Natural selection uses abstract dents and grooves in abstract design spaces that
constrain what happens and can be replicated. But it cannot work without a
"low-level" medium of the right sort, and chemical matter is the only known
candidate, for reasons spelled out by Ganti (and apparently nearly guessed by
Newton).
The importance of quantum mechanisms
Quantum mechanics plays a crucial role. Many years ago, the physicist Philip
Morrison gave a series of lectures on BBC TV. One of the points he made was
that the molecular stability required for genetic information to be preserved in
complex molecules for long periods of time in the life of an individual, and
across generations, despite a great deal of thermal buffeting, would be
impossible without the discreteness of quantum mechanics. Nothing in Newtonian
mechanics could explain that. Similar points had previously been made by
Schrödinger in his (1944), discussed in more
detail in the companion paper on construction kits.
I have produced a draft annotated collection of extracts from that book here:
http://www.cs.bham.ac.uk/research/projects/cogaff/misc/schrodinger-life.html
All I am doing is making the same point about many biological structures, not
just the genetic material. This includes structures encoding many different
forms of information required by individuals, at various stages in their
development and during performance of complex individual or collaborative or
competitive actions. Antibodies are another example.
Curiously, many writers attempt to make use of quantum indeterminacy in
explaining how minds can exist in a physical universe. In contrast, I am
emphasising the role of quantum determinacy, the stability of certain structures
that could not be stable in a Newtonian universe, as the basis for enduring
information stores needed for increasingly complex forms of life.
I think there is also something important about the fact that chemistry based
information structures can have both their geometrical relationships and their
physical shapes changed in ways that affect later uses of the information.
It may be the case, for example, that searching for ways of moving
already assembled but flexible structures encoding information
into new
configurations
that meet new requirements is possible in physically realisable time-scales,
whereas the corresponding search
in a space of bit patterns or symbolic structures
would require more than the
expected lifetime of the whole universe.
These processes seem to go beyond what Turing machines and current electronic
computer architectures can support. But that claim needs to be made
mathematically precise, in order to be interesting.
Requirements for rapidly changing virtual machine structures
There are additional requirements if biological mechanisms are to be able to
support rapid reorganisation of virtual machine structures. If you watch water
flowing rapidly over rocks from above, a flock of birds taking off or landing,
or if you listen to a performance of a five part fugue, your mental contents
will be changing in ways that require rapidly reorganised information
structures, that could not be achieved by rapidly rearranging the required
number of physical objects, e.g. parts of brains.
(There are many reasons, including energy required, path
planning required to avoid collisions, etc. etc.)
In the last half century, we have learnt many
techniques for achieving rapid reorganisation of complex structures in
virtual machinery implemented on computers.
The techniques include changing "addresses" of
information structures (replace address of structure A with address of structure
B, instead of moving the whole structure from one place to another, or creating
and destroying physical links). There are also "inheritance" mechanisms whereby
if reference to one complex structure is replaced by reference to another
complex structure, some of the references to parts of the original are
automatically (implicitly, but accessibly) replaced
by references to parts of the new one (e.g. the left
front wheel).
E.g. suppose I am told that instead of my car, your car is now in a garage whose
dimensions I know allow only one car, facing in one of two directions. Then I
don't need to be told also that the left front wheel of your car, but not the
left front wheel of my car is in the garage, and that your left front wheel is
either where my car's left front wheel was or where the right back wheel was,
relative to the structure of the garage, not the car.
The uses of virtual information processing machinery have made profound
differences in the last half century to what can be done using computers,
as summarised in
this
discussion of "virtual machine functionalism". Examples of such requirements
for human visual mechanisms can be found in this presentation:
http://www.cs.bham.ac.uk/research/projects/cogaff/talks/#talk88
Biological virtual machinery and quantum mechanisms???
A remaining open question is how biological virtual machines might be
implemented so as to be rapidly re-linked when required. I have no idea whether
mechanisms of quantum superposition could be relevant.
Large collections of
partial information structures ready to be linked rapidly into fully
instantiated (and changing) completed information structures may be of much more
profound importance than dead and alive cats. But that hypothesis needs to be
supported by a theory explaining how relevant superposed alternatives can come
to be created by learning processes.
In simple cases multi-stable dynamical systems with "winner takes all"
mechanisms could do that. But we need multi-stable generative systems, capable,
for example, of constructing a novel sentence, or a novel interpretation of a
complex picture never seen before (like
the "hidden dalmation"
picture), or switching between two interpretations as in the
necker cube or duck rabbit images below.
In the case of the cube it would be possible to explain the ambiguity and
flipping process by constructing an algebraic representation containing unknown
numerical values, where there are alternative sets of numbers that produce
coherent interpretations. But in the case of the duck-rabbit entirely different
sorts of semantic interpretations for complex parts are required (mouth, ears,
bill, eye), and -- even more interestingly -- one animal "faces left" while the
other "faces right" a very abstract and subtle kind of semantics, whose internal
representation (encoding) is far from obvious.
Similar problems arise for explanations of what the brain might be doing when
switching between interpretations of the well known
Old-woman/Young-woman picture). That sort of thing cannot be done simply by
switching interpretations of separate fragments of the image: it requires parts
of the image to be grouped in different ways for different interpretations, and
information about different 3-D parts in quite different 3-D relationships to be
assembled, as well as assignments of different biological roles to different
parts. (Compare the Johansson moving and stationary light videos.) Anyone who
wishes to invoke quantum indeterminacy of any sort has many questions to answer,
if the invocation is not just hand-waving.
In particular, the types of alternative interpretations of visual contents
discussed here don't seem to have anything to do with alternative solutions to
sets of equations relating numerical variables. So a pair of alternative states
can't be specified by setting up some mathematical description that is common to
the two states except for changes in the numbers used.
Some of examples of experienced ambiguity require switching between two
structures that are more like two parse trees than like two sets of solutions to
simultaneous equations.
An old example is the pair of interpretations of "He saw the man with the
telescope". In one interpretation "with the telescope" specifies which man, if
only one man in view had a telescope. In the other interpretation "with the
telescope" explains how it was possible to see a man (and perhaps recognise him,
or see what he was doing) by mentioning the use of a telescope to see him.
Likewise "Flying aeroplanes can be dangerous" is ambiguous between the dangers
of aeroplanes in flight, and the dangers of doing the flying.
Further examples of challenges and
possible types of solution can be found in
This is all still much too vague. Whether and how the idea can be made more
concrete with more explanatory power, is a long term question. Answers may
emerge from other strands in the Meta-Morphogenesis project.
http://www.cs.bham.ac.uk/research/projects/cogaff/misc/meta-morphogenesis.html
Suggestions and criticisms welcome!
Types of construction kit (Added 8 Nov 2014)
Extended 15 Nov 2014
I have met several people who, like me, believe that playing with meccano
construction kits for several years had a profound educational impact. There are
many other types of constructional toys that children can play with, including
plasticine, sand, mud, paper-scissors-glue-clips, lego blocks, tinkertoys,
fischertechnik, geomagnetic, and no doubt many more.
An important feature of many, though not all construction kits, is "generative
power": whatever has been assembled always permits additional parts to be added
(though in some cases it may be necessary first to partially disassemble before
extending). In some cases, e.g. plasticine, sand and mud, there is continuous
(or almost continuous) variety in what can be added or modified at any stage,
because existing portions can be continuously deformed in a variety of
ways -- prodding, squeezing, stretching, bending, twisting, etc, and because the
size, location, and orientation of a new part added allow a continuum of
possibilities.
For other sorts of kit the available extensions or modifications may all be
discrete (e.g. lego bricks), or a mixture of continuous and discrete, e.g.
meccano. In any case, features of the "minimal" components, i.e. the components
that come pre-manufactured, mathematically constrain the kinds of structures
that can be assembled, and if they are not all rigid structures, the types of
relative motion of parts (types of deformation) will also be mathematically
constrained by the degrees of freedom available after a new part has been added,
or two previously assembled structures are combined.
Some construction kits include motors, which may be driven by springs, elastic
materials, flywheels, batteries, mains electricity, heat (toy steam engines),
wind, and possibly others. In such cases, not only does the construction-kit
mathematically constrain the kinds of structures that
can be assembled, it also constrains the kinds of processes that can be produced by assembled constructions
with motors included, charged if necessary, and turned on.
Even more variety can be produced if the kit provides sensors and information
processing units (e.g. programmable computers) that can read sensor information
and transmit control information to the motors, or to groups of controllers
controlling motors. Understanding the combined consequences of the various sorts
of components, and in particular understanding what sorts of behaviours the
constructions can produce in different environments may require the resources of
mechanical and civil engineering, chemical engineering, electrical engineering,
and control engineering, the last of which subsumes a great deal of computer
science and artificial intelligence, at least in principle, although the
teaching of control engineering may focus on a narrow subset, in particular the
subset for which standard sorts of mathematics (calculus, differential
equations, linear algebra, probability theory, etc. are useful.
The development of computers and programming languages made available new sorts
of construction kits whose components included virtual machinery
(Sloman 2004/1978). (I suspect biological evolution did
something similar long before human engineering capabilities evolved, but the
details are very complex and hard to investigate. So researchers tend to focus
on brains instead.)
This document is concerned with the question: what sort of construction kit of
physical and chemical parts was available at the time the earth was formed, and
what was it about that kit that allowed the processes of natural selection to
produce the variety of life forms on this planet, from sub-cellular entities to
elephants, giant redwood trees, and giant fungi, which not only display an
extraordinarily rich variety of physical forms, but an even richer variety of
physical processes characteristic of the species, controlled by information
processing mechanisms that we have only just begun to understand.
Many researchers assume that all such processes can be replicated, or simulated
on a typical digital computer, possibly using a network of communicating
computers, an assumption that often goes with assumptions about the forms of
information processing used by biological mechanisms. This should be regarded as
an open question, until we have deep theories that explain how living things
work, and, in particular, how they process information.
Many scientists who have thought about such issues have come up with theories
that assume that all the states and processes in such systems can be represented
by collections of numbers and relations between the numbers, including algebraic
expressions and differential equations. A very influential example is the
excellent little book by Braitenberg:
Valentino Braitenberg, 1984,
Vehicles: Experiments in Synthetic Psychology,
The MIT Press,
Cambridge, MA.
Unfortunately many of the researchers who attempt such general theories assume
that all the states, processes, sensor contents, and motor signals that occur in
such systems can be adequately represented using collections of numerical values
of physical states, relations or processes. That would exclude information
structures formed using a grammar, parse trees, and networks whose nodes are
structures rather than scalar (numerical) values or sets of scalar values --
among other things that have been investigated by AI researchers, computer
scientists and software engineers in the last half century. It would probably
also exclude important types of chemical control mechanisms, and many sorts of
virtual machinery.
The sort of construction kit considered here needs to be able to explain how
some of the forms of information processing on the planet involve thinking about
and proving theorems about infinite structures, e.g. the natural number series,
the set of possible Turing Machines. This suggests that the construction kit
itself needs to have infinite generative power, a feature Chomsky (and others)
famously attributed to the grammars of human languages.
It is likely that physical limitations (e.g. gravity, speed at which
information can be propagated) will limit the physical complexity of the
integrated information processing systems our chemical construction kit can
support.
This document is not about explaining particular happenings, but explaining
possibilities, i.e. answering questions of the form: "How is X possible?" or
"How are things of type X possible?". This is a form of explanation that is not
widely recognised in philosophy of science. I discussed such explanations in
Chapter
2
of my 1978 book:
A creationist view
An example of the "creationist" scientific thinking to which this is a partial
response can be found in
http://www.icr.org/article/does-entropy-contradict-evolution/
Henry Morris, 1985. Does Entropy Contradict Evolution?. Acts & Facts. 14 (3).
(Not endorsed here, except as an illustration of
the arguments used.)
Of course, my discussion of possibly adequate physical conditions to serve as a
starting point for evolution as we have known it, could be seen as inviting
creationists to abandon arguments that natural selection needs divine guidance,
and instead adopt a quite different sort of creationist argument: namely, that
the provision of initial conditions capable of supporting natural selection,
such as the existence of chemical elements, needs divine guidance. I don't
expect coherent answers to come from any traditional theology for reasons
explained here:
http://www.cs.bham.ac.uk/research/projects/cogaff/misc/varieties-of-atheism.html
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ACKNOWLEDGEMENT
Some of the ideas here are loosely related to a conversation with Ron Chrisley
during the two years he spent working here, around twelve years ago, though he
can't be blamed for any mistakes I have made.
RELATED DOCUMENTS
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REFERENCES AND LINKS
(In no particular order. More to be added.)
-
Paul Davies,
The Fifth Miracle: The Search for the Origin and Meaning of Life,
Simon & Schuster, 1999,
-
Richard Dawkins
-
Terrence Deacon, 2011,
Incomplete Nature: How Mind Emerged from Matter,
W.W. Norton & Company. ISBN 978-0-393-04991-6
https://en.wikipedia.org/wiki/Terrence_Deacon
-
Peter Hoffmann (video lecture),
Life's Ratchet: How Molecular Machines Extract Order from Chaos,
November 19, 2012,
https://www.microsoft.com/en-us/research/video/lifes-ratchet-how-molecular-machines-extract-order-from-chaos/
-
Peter M Hoffmann, 2016,
How molecular motors extract order from chaos (a key issues review)
10 February 2016,
Reports on Progress in Physics,
Volume 79, Number 3,
IOP Publishing Ltd.
https://iopscience.iop.org/article/10.1088/0034-4885/79/3/032601/meta
-
Stuart Kauffman,
At home in the universe: The search for laws of complexity,
Penguin Books, 1995,
-
Alan Kay
-
Marvin Minsky
-
Seymour Papert
http://www.papert.org/articles/SituatingConstructionism.html
Situating Constructionism
By Seymour Papert and Idit Harel
-
Jean Piaget
-
Erwin Schrödinger,
What is life?, 1944, CUP, Cambridge,
Extracts annotated by A.Sloman can be found here
http://www.cs.bham.ac.uk/research/projects/cogaff/misc/schrodinger-life.html
-
[Sloman 1969]
Aaron Sloman (1969) How to derive "better" from "is".
In American Philosophical Quarterly 6:43-52,
http://www.cs.bham.ac.uk/research/projects/cogaff/62-80.html#1969-02
-
Alan Turing
-
.....
Installed: 29 Oct 2014
Last updated: (Deacon) 26 Oct 2018; (Ratchets) 7 Nov 2018; 28 Jul 2019
24 Jan 2016 (Mainly re-formatting, and linking to paper on construction kits)
13 Nov 2015
(more links to biology, construction kits and Schroedinger).
2 May 2015: Minor reformatting. 21 Jul 2015 (Added Nature reference)
18 Jan 2015 minor changes. Added link to
construction-kits.html
15 Nov 2014 (comparison with comet-based explanations, and Ganti's
ideas)
31 Oct 2014; 2 Nov 2014; 6 Nov (combinatorics discussed); 8 Nov,
11 Nov 2014;
Maintained by
Aaron Sloman
School of Computer Science
The University of Birmingham
