Engines of Creation

By: Eric Drexler

Chapter 1: Engines of Construction

Creation involves the manipulation of matter and hence atoms.
To date, our techniques have been through “bulk technology”: the imprecise manipulation of
mass numbers of atoms. “Molecular technology,” or “nanotechnology,” is a bottom-up approach
in which atoms are precisely joined.
Proteins can literally function as microscopic machines (i.e.—flagellum engines, actin-myosin
crossbridges, etc.).
Designing proteins to perform a given function is extremely difficult given the complexity of the
protein folding process.
The ability to design proteins would be a first step towards useful nanotechnology.
Proteins are not ideal for nanomachines since they are fragile and do not function at temperature
extremes.
Each generation of nanomachines will give engineers new capabilities and will allow them to
build even better nanomachines. More generally, technology empowers the development of more
advanced technology.
Microfibers are the first use for nanotechnology. They are simple, repeated polymers. Complete
structures will require another level of complexity.
Protein machines are like enzymes in that they can precisely join or split two molecules. They
are also like ribosomes in that they are programmable. However, protein machines will not be
restricted to manipulating amino acids only and will be able to make structures out of metals.
Second-generation nanomachines (some will be Universal Assemblers) will be synthetic instead
of protein-based and will be able to perform the same functions as their predecessors, but better
and under a wider range of conditions.
The Uncertainty Principle does not make atomic manipulation impossible. Indeed, it has almost
no effect. Anyway, the existence of ribosomes shows that molecular machines are possible.
Thermal vibrations pose more of a threat to proper molecular machine function than the
Uncertainty Principle does, but the barrier is still overcome—DNA polymerases assemble
proteins and correct most of the thermally induced errors. Man made nanomachines could have
their own proofreading systems.
Radiation breaks bonds between atoms, damaging larger structures. Life has adapted to this with
repair mechanisms. Nanomachines, while less vulnerable to radiation hits thanks to their small
size, will have to have such repair mechanisms as well.
Evolution has failed to produce assemblers because the DNA/RNA/ribosome system is suited to
making proteins only. Assemblers are simply too much of a leap to evolve naturally.
“Improved molecular machinery should no more surprise us than alloy steel being ten times
stronger than bone, or copper wires transmitting signals a million times faster than nerves.”
Assemblers will allow bottom-up construction of computer chips, allowing for 3D chips without
any flaws that hinder computing. Current methods only allow for 2D chips with molecule-sized
flaws.
Computers can be either mechanical or electrical. The first mechanical computer was invented in
the mid-1800’s by Charles Babbage. Large-scale mechanical computers are impractical because
of slow speeds, but microscopic mechanical computers with components a few atoms across

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could function faster than electronic computers since the components could be placed much
closer together.
Disassemblers could take apart objects, atom by atom, and record their structure for replication.
Genetic technology is the first step towards synthetic nanotechnology.
Each advance shall enable the next.
The advancement of technology is inevitable and can be barred only by worldwide destruction or
worldwide regulation.
Molecular machines will represent a technological revolution on par with the advent of nuclear
weapons or the discovery of antibiotics. Life will be profoundly affected.

Chapter 2: The Principles of Change

Understanding the principles of change will help us to understand the potential for good and evil
presented by nanotechnology.
Evolution is fueled by selection and random variation (mutation). Evolution occurs in living
organisms and in molecules (proteins and RNA).
Geologists and archaeologists the world over have clearly observed that species of specific types
are found in specific layers of Earth, and that each layer’s age can be ascertained. Furthermore,
the layers always occur in the same order, indisputably indicating that different types of life
predominated on Earth during different stages of our planet’s history.
Drexler agrees with Kurzweil that technology and intelligence have effectively enhanced the rate
of evolution by thousands fold.
Technology also evolves incrementally. Most advancement results from evolution rather than
revolution. In rare instances, innovation occurs entirely by accident.
Selection also occurs in the workplace, factory and free market. Evolution is everywhere.
Technology gives humans the edge over the natural world because our intelligence allows us to
enhance our abilities far faster than nature can evolve (in most circumstances).
Progress cannot be stopped.
The human mind is the information repository for technological innovation just as the cell
nucleus is the information repository for biological evolution.
Memes are attitudes and beliefs held by people. Most are selfish, but protective. A common
meme is the tendency to reject risky new ideas in favor of older, tested ideas. This has both
advantages and disadvantages.
The principles of change will shape the development of nanotechnology.

Chapter 3: Predicting and Projecting

The development of technology needs to be controlled to ensure public safety.
On December 30th, 1959, Dr. Richard Feynman gave his speech “There’s plenty of room at the
bottom” to the American Physical Society. His speech was based around three major ideas: first,
manipulating atoms individually to build molecules did not violate the laws of physics, second,
the technology to do so would eventually arrive as our ability to make smaller and smaller
generations of robots improved, and third, the arrival of such technology is inevitable.
While Feynman and others correctly predict that nanomachines will emerge, Drexler resists the
idea of setting a timetable for the development of the technology. As has been seen with past
technologies, “The nuances of detail and competitive advantage that select winning technologies
make the technology race complex and its path unpredictable.”

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The first functioning assemblers will be a breakthrough that might occur very suddenly after
years of quiet development.
Depending on how we handle the technology, the human race could be led to destruction or
abundance.

Chapter 4: Engines of Abundance

March 27th 1981: NASA scientist predicts that self-replicating machines will exist within 20
years. Drexler cites this as an example of how an expert can be sure of something’s invention,
but not of the exact date of invention.
Advances in automation will naturally lead to replicating machines.
Large machines make smaller machines already. The process at all levels will become
increasingly automated until machines do all of this themselves.
Replicators that build nanomachines will be complex and themselves with be comprised of
successive nanomachines that perform different construction functions.
Assemblers are mechanical ribosomes that can be programmed to build any type of molecule.
They use mechanical arms to manipulate atoms and get their instructions from a synthetic “strip”
of DNA-like material.
Drexler describes a nanomachine assembler as being very similar to a ribosome.
Nanomachine manipulator arms would move millions of times a second. Drexler cites the
quickened pace of appendage movement as animals decrease in size and the fast pace of enzyme
function as proofs.
Drexler approximates the number of atoms needed for an assembler to be less than a billion. At
one million operations per second, the assembler could make a copy of itself in 15 minutes—the
same time for a bacterium to divide.
Replicators would grow exponentially in number but would be constrained by available
resources.
Heat becomes an issue as assembler speed increases and it serves as a limiting factor.
Molecular assemblers could build simple, constituent parts that would then be put together with
larger devices similar to those already in existence.
Drexler’s idea of how assemblers would make a rocket engine:
-A large vat is filled with assemblers suspended in liquid.
-A nanocomputer with the stored instructions is inserted into the center of the vat.
-The nanocomputer has junctures where assemblers can join to it and download its instructions.
-Nearby assemblers join the nanocomputer and in turn join themselves to other assemblers via
arms until an assembler “scaffolding” of the rocket engine is formed.
-The fluid is exchanged to remove excess assemblers and to pump in a metal- and energy-rich
solution.
-The assemblers activate, using the solution both as a construction material and as fuel for their
own functions.
-The assemblers are surrounded by channels through which the solution flows, delivering needed
materials and removing excess heat. The flow is powered by flagellar motions of specialized
assembler arms.
-The resulting engine is extremely strong and light, seamless, and uses no nanotechnology for its
functioning.

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Future technology could incorporate assemblers into the functioning of machines. Vascular
systems could allow nanobots to circulate throughout machines, repairing them or changing their
shapes to suit changing requirements.
Teams of trillions of biological assemblers can build complex objects like the human brain, or
massive objects like whales. It is no stretch to imagine them building rocket engines or
computers.
Disassemblers will break down raw materials into individual atoms for assembler use.
Nanotech manufacturing could be done extremely quickly, cheaply, efficiently, and cleanly.
The technology represents the ability to make almost anything from almost anything else for
virtually nothing in cost.

Chapter 5: Thinking Machines

The expert systems of Drexler’s day succeeded in only narrow endeavors.
The argument that computers cannot be made intelligent because it hasn’t been done yet is
fallacious. Steam engines did not fly, but they demonstrated mechanical principles later used in
airplanes. Prehistoric worms did not think, yet our brains use neurons like theirs.
Drexler makes an argument for the possibility of making A.I. smarter than humans: Our primate
ancestors evolved into more intelligent species without even willing it. Modern human scientists,
however, have the advantage of being able to direct technology, which is capable of improving
upon itself far faster than biological evolution.
Psychobiologists have found no evidence supporting the theory that the human brain contains
some irreproducible substance that imparts the ability to think and hence restricts intelligence to
the domain of human beings.
Some have claimed that machines cannot ever be truly intelligent. Alan Turing is a British
mathematician who convincingly argued that “intelligence” is judged by the quality of a person’s
speech, and that machine intelligence should be gauged in the same manner. Thus, he devised the
Turing Test. The computer must be able to convincingly carry on a conversation with a human
judge to pass.
The argument that machines cannot be self-aware is moot since there is no objective measure of
self-awareness.
1Technical A.I. and Social A.I.
Drexler talks about the beginnings of genetic algorithms back in 1986.
A properly programmed computer can outperform humans at complex tasks.
Using information from experts and good programming, a computer may generate and test
millions of potential solutions to a given problem and find the best one. The simultaneous
calculations involved would be impossible for even a large group of humans working together. In
this way, computers augment human problem solving capabilities, specifically in the realm of
engineering.
Improved simulation programs are just as important as improved algorithms and heuristics.
Drexler believes that computer-aided design will speed the rise of nanomachines [yeah, along
with everything else].
Advanced A.I. will emerge step-by-step. [J. Storrs Hall agrees and explains further.]
Any nation that arrests the development of A.I. will only put itself at a disadvantage as other
states continue research. Only a world government would be capable of stopping its
development, and even then, the efforts might fail as computer cost performance (divorced from
A.I. programming) would still improve and underground groups would thus eventually gain the

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ability to make A.I.
Drexler believes that A.I. must be carefully developed to ensure the public good.
Drexler recognizes that A.I. will require a vast improvement to our understanding of the human
mind, and he consequently refuses to set a date for the emergence of A.I.
Though Drexler agrees with Kurzweil that broad A.I. (not exclusive to only one application) will
come from reverse-engineering the human brain, he seems to break with Kurzweil in that he
believes an even less exact copy of the brain needs to be made [not totally clear what Drexler
thinks].
Drexler agrees with Kurzweil that the advent of A.I. will speed overall technological
advancement.
The human brain does a huge number of things at once, but very slowly [parallel processing?].
Computers can only do one thing at once, but with great speed.
The superior transmission speeds possible with electronic circuitry suggest that A.I.’s would be
able to think far faster than synapse-based humans.
Drexler suggests making a computer brain with a structure basically the same as a humans and
with nanomachines present to alter the interneural connections to mimic human brain synapse
paring and formation.
Due to the superior efficiency of machines, a computer “brain” with the same number of neurons
as a human counterpart would fit into a cubic centimeter.
Heat dissipation would be the biggest impairment of A.I. abilities. [Does not consider Kurzweil’s
reversible computing scheme?]
Assemblers will be able to precisely construct materials, leaving less room for error and
obviating the need for many experiments.
An A.I. or team of A.I.’s commanding nanomachines and assemblers could totally replace all
human scientists and engineers. All progress and new developments would be handed over to the
A.I.’s.
Drexler agrees with Kurzweil that the rate of progress has been exponentially increasing on the
cosmic scale. He also foresees the Singularity–an abrupt change to existence caused by
exponentially increasing machine abilities.
The machines will make all human labor unnecessary.

Chapter 6: The World Beyond Earth

Drexler believes that it is humanity’s fate to colonize space [like Kurzweil and also a logical
belief].
The general public became disillusioned at the prospects of space colonization after the missions
of the 20th century revealed our solar system to be devoid of life outside of the Earth.
Drexler argues that spaceflight is expensive because spacecraft are not manufactured or used in
quantity and are seldom reused, resulting in a failure to capitalize upon economies of scale.
Drexler predicts the emergence of mobile telephones capable of using satellites for worldwide
communication.
Drexler predicts that the weightless environment of space will be advantageous for certain
industrial applications and will thus spur companies to build facilities in space. The overall
increase in activity will make spaceflight cheaper and more common.
In deep space, rockets are burdensome. Solar sails and careful exploitation of gravitational forces
could move spacecraft throughout our solar system in all directions.
A light sail would be kilometers wide and made of reflective material thinner than a soap bubble.

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Such large and delicate structures would be easily damaged during transport from the surface of
the Earth, so it would make sense to build them in space. The ability to build them will require a
much improved knowledge of space fabrication techniques.
Solar sails will be extremely cheap to operate.
Mining asteroids in our solar system will provide trillions of dollars in revenue and a steady
source of elements rare on Earth. Mining other planets, however, will be harder.
Space stations could be utopias and could allow humanity to expand beyond the Earth [would be
kind of depressing for most people to live on a small, isolated space station, no matter how nice
it was made].
Drexler believes that A.I. and nanotech will allow spacecraft to be built quickly and cheaply,
accelerating our colonization of space.
Nanotechnology will enable designed objects to have very advanced properties. Drexler does an
interesting description of an advanced space suit.
A.I., assemblers, and advanced space capabilities will revolutionize industry.
-Automation provided by A.I. and nanomachines will reduce human labor costs and human
involvement in general to a bare minimum.
-Capital will also be minimized since assemblers are self-replicating and can build copies of
themselves as needed to perform other purposes. A small investment in capital in the form of a
single A.I. commanding a single assembler could spawn an enormous factory in just a few hours
or days.
-Materials costs will be drastically reduced since raw materials could be converted to useful ones
by nanomachines. Dirt and air could provide the elements for most projects.
-Energy costs would dive since assemblers would be able to produce highly efficient solar panels
for almost no cost. They would also be able to break down physical sources of energy to convert
chemical to free energy.
-Assembler-based manufacturing facilities could be very small, or if very large, could be put in
space or underground, so land costs are low.
-Waste would not be produced since assemblers are 100% efficient in terms of matter use.
-Drexler envisions underground tunnels built by cheap digging machines that could be used to
transport goods without disturbing anyone. But assembler facilities in every town would
themselves make distribution networks less necessary [though some products would certainly
require specialized manufacture facilities].
-Governments with assemblers will have less of a reason to tax.
Drexler envisions massive space stations the size of entire continents with natural landscapes like
those seen on Earth.

Chapter 7: Engines of Healing

The ill, aged and injured all share a similar feature: misarranged atoms. Nanotechnology will
give us the ability to rearrange atoms into whatever stable pattern we wish, therefore radically
improving our abilities to control our own health.
Drexler correctly predicts the increases in emphasis on designing drugs that work at the
molecular level (agonists and antagonists).
Proteins (molecular machines) in the right environment will work whether they are part of a
functioning cell or not.
Nature draws no line between the living and the nonliving (viruses).

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Drexler mirror’s Kurzweil’s point that the complexity and beauty of human beings is
undiminished by the fact that we are composed of organic machines. We are greater than the sum
of our parts.
Assembler built nanomachines will repair cells in the future.
Disassemblers will allow doctors to catalog every part of each type of human cell, creating
biological blueprints that can be used to repair old cells or to create new ones.
Drugs and surgeries can only encourage cells to repair themselves. Nanotechnology will allow
direct control.
Nature already demonstrates that the basic principles required for medical nanotechnology are
sound:
-White blood cells travel through tissues and viruses enter cells, proving that it is possible to
move through the body and access the internal machinery of cells.
-Receptors and antibodies show that recognition of specific cells is possible.
-Digestive enzymes disassemble select types of molecules.
-Replicating cells show that generation of new cells is possible if components are constructed
one at a time.
-The T4 phage shows that reassembly is possible for some types of molecules.
Natural systems show us the lower bounds of what is possible.
Medical nanobots will be able to enter cells, examine their structures, compare their structures to
what is known of healthy tissue, and repair the structures accordingly.
Medical nanobots would be the size of viruses or bacteria, but thanks to their engineered nature,
would be more compact and functionally efficient.
The first of such nanobots would be specialized for only one function each, like recognizing and
correcting a certain type of enzyme deficiency or one form of DNA damage, but, with the aid of
technical A.I., the nanobot abilities would expand.
Incredibly small computers will be in each nanomachine to direct its functions.
Cellular replication machines can reproduce a mammalian cell in just a few hours while
themselves taking up little volume. This shows that nanomachines can work rapidly in repairing
cells.
Biological nanomachines do not overheat cells while they function, so there is no reason to
believe it would be different with synthetic nanomachines [but what if they are engaging in
intensive activity like repairing an entire body?]
A device that compares the same regions of multiple strands of DNA at once to check for errors
would itself have an error rate inversely proportional to the number of strands used.
A medical nanobot could be such a device and could correct DNA mutations in that manner.
Nanobots will incorporate several different computers tasked for different purposes and in
control of different manipulators.
Advanced medical nanotechnology will provide a guaranteed cure for cancer in every cell.
Medical nanobots will be able to track down and destroy pathogens and cancer cells, dissolve
arterial plaques, repair damaged DNA, and excise portions of viral DNA inserted into the host’s
genome.
Potential aneurysms could be detected and repaired.
Moderate neural damage resulting from stroke could be repaired by restoring blood circulation.
Though nerve tissue could be regrown, unique neural patterns holding memories and skills could
not be regenerated without knowledge of their structures. This is the limit to tissue repair.

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Brain biochemical abnormalities could be corrected with nanotechnology, curing some mental
disorders, but most mental disorders have cognitive rather than biochemical sources.
Drexler holds the mind to be something beyond technological alteration. [remains to be seen]
Drexler talks about biostasis. In a multi-step procedure, different types of nanomachines enter
cells to first stabilize cell structures and then replace water with preservative fluid. Some cellular
damage invariably occurs, making cell repair nanobots an integral part of the resuscitation
procedure, which is essentially the preservative procedure in reverse. Structure is preserved
while function is suspended.
Biostasis could be used to preserve injured people until adequate medical treatment is available,
for long-distance spaceflights [speed of light time effect as a counter?], or to preserve dying
people for a future time when medical science has a cure for their condition.
Since medical nanobots will be able to reconstruct tissue, understanding diseases will no longer
be important to health [might be detrimental to medical research].
Aging is natural, but so was smallpox.
Improvements in sanitation and drugs have increased human longevity by reducing bacterial
illness [along with better nutrition], but the basic limits on human lifespan [Hayflick limit?] have
been unchanged.
Drexler cites the 1986 rise in aging research and predicts that such efforts may yield substantial
increases in human lifespan over the next 10-20 years [wrong].
Since aging is just the result of damaged cell machinery and since medical nanobots can repair
cell machines, medical nanobots will be the cure for the aging process and will indeed allow it to
be reversed.
Drexler, like Kurzweil, stresses the need for people to live to a certain point of technological
advancement to live indefinitely.

Chapter 8: Long Life in an Open World

Advances have allowed us to cheat early death but not to extend minimum lifespan.
The argument that “since nature can’t extend life indefinitely, neither can we” is flawed because
it assumes that we cannot devise better ways to repair cells. In fact, we can.
Better biological self-repair mechanisms are possible, but are rare since the process requires a
large investment of cellular energy. Nature mostly selects for animals with short lifespans and
fast breeding cycles.
But DNA damage is only part of aging. Death seems to be programmed into organisms. A gene
that helps the youthful organism but is detrimental in old age will replicate well since most
animals never live to old age anyway.
Dr. Leonard Hayflick discovered that cells stop reproducing after a certain number of divisions,
meaning that the cell fails to make a replacement for itself before it dies. He named this
phenomenon “the Hayflick Limit.” Its implications are that the body will die, cell by cell, after a
certain age. Hayflick speculates that the limit prevents cancerous tumors from dividing
excessively in early animals, protecting them.
Nanomachines could be used to clean up pollution:
-Rearrangement of atoms to convert toxic substances into harmless ones.
-Disassembly of radioactive wastes into microscopic particles and then embedment in the Earth.
-Housing of radioactive wastes in self-repairing sealed storage units.
Nanomachines could extract CO2 from the atmosphere, and through deep “roots” could return
the carbon back into the empty oil fields if desired.

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Robots will reshape the contours of the Earth to repair mining damage.
Other robots will eat litter.
Others will adjust vegetation to restore lost ecosystems.
Mechanical “roots” under the soil will extract harmful chemicals and pesticides to protect the
environment.
Genetics technology could also be used to revive extinct species.
Increased space capabilities granted by advances in nanotech engineering will make us more able
to defend against asteroid impact.
Medical nanotechnology will allow people to live longer, thus increasing the population. But
simultaneously, industrial nanotechnology will allow us to meet our material needs without
polluting the atmosphere, allowing the Earth to support more humans without increased strain.
Spaceflight will allow people to leave the Earth for space stations or other planets if the former
became too crowded.
Eventually, the material resources of our solar system would prove finite. Drexler provides no
direct solution to this and merely says that the people of the future will have to figure out a way
to deal with it. [Kurzweil, by contrast, believes in faster-than-light travel and a concomitant
expansion into the infinite reaches of space by the 22nd century.]
Longevity will not lead to cultural stagnation as old people dominate society for two reasons:
-Spaceflight will allow younger people to move out as they wish to establish their own homes.
New ideas could be tested and proven to work for all.
-Nanomachines will allow eternal life and youth, meaning that the very old will not be mentally
rigid thanks to diminished brain mass like the ones today.
The opportunity to live indefinitely and to escape the ravages of old age may make people more
averse to warfare since death would be a more cruel fate.
But this unwillingness to fight may prove disadvantageous as well: People might be unwilling to
stand up to oppressive regimes or to wage small wars that may avert larger, more destructive
wars.
People who lived indefinitely could behave in one of two ways: hedonistically or stoically. In the
latter case, people would be willing to endure great hardships because, thanks to their long lives,
they would be sure that they would bear the fruits of their labors in later centuries.
Drexler believes that longevity will make people more hopeful and willing to improve their
condition and their world since all will have the opportunity to live in that better world, even if it
is decades or centuries away.
Drexler believes that full medical “rejuvenation” will be possible in the 2050’s.

Chapter 9: A Door to the Future

Reversible biostasis techniques need not exist for a person to successfully “hibernate” into the
distant future—future medical technologies will make it possible to repair damage caused by
current freezing processes.
The brain is the only organ that must be preserved.
Alteration of protein function and quantity is the basis of memory and personality as well as all
other physiological adaptation.
Changes to neurons cause morphological changes.
Resuscitation requires cell repair machines, but biostasis is already available.
Biostasis has existed for decades. Specimens for electron microscopy are fixed using
glutaraldehyde, which is a short molecule that binds proteins at either end, holding them in place.

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The chemical is pumped into blood vessels and diffuses into cells.
Afterwards, other preservative chemicals are injected to do a more thorough job.
According to Drexler, chemically fixed specimens show a preservation of molecule machinery.
The next step in the process is the displace water and to solidly pack molecules inside and
around the cells. “Cryoprotectants” such as propylene glycol, ethylene glycol, and dimethyl
sulfoxide do this and also protect the cells from lysing damage that occurs at freezing
temperatures.
Solidification without freezing is called vitrification. At cold temperatures, the aforementioned
molecules basically become a solid “glass” that does not flow and keeps cell machinery firmly in
place. [But can this whole process be done fast enough after a person dies to prevent brain
damage?]
Embryos are preserved with vitrification.
Robert Ettinger first proposed the idea of cryonics in 1962, and his book gave birth to the
movement.
Drexler claims that freezing usually does not lyse cells and that the damage is usually more
subtle and reversible. He points to the successful and spontaneous revival of frozen embryos.
[The effort to freeze organs to extend viability for implantation would come to nothing,
unbeknownst to Drexler.]
Drexler believes that the public has been misled about cryonics.
Resuscitation will occur in the reverse order of biostasis; patients frozen later with more
advanced techniques will be revived first while later advances in technology will allow earlier
people to be reanimated.
A series of different nanomachines with different functions restores health to a preserved person.
Drexler denies the immortality is possible, but radical life extension is.
More people will choose biostasis as the technology for revival comes closer and the public
becomes more aware of it. Costs will drop as well.
Drexler makes the following comparison:
Why do people not preserve themselves cryonically? Because the technology to revive them
does not yet exist. But why will the same people save money for the college educations of their
children? There is also no guarantee that the child will go to college. The parents realize that the
child will mature, but at the same time they do not see that technology will mature.
People doubt the promise of cryonics because it sounds too incredible, but they fail to see that
the 20th century alone has seen incredible advances that many at the beginning would have never
predicted.
One factor explaining the public’s failure to use cryonics is the high cost.
Resuscitation of preserved people is likely because automated systems will be able to do it at no
cost and the people of the future will be wealthy and have time to do such things. Many will also
have loved ones in cryostasis, and might also empathize with non-family members frozen as
well.

Chapter 10: The Limits to Growth

Gravity is a curvature of space-time.
Machines that extract energy from the gravity forces generated by things being dropped into a
black hole would be 50% efficient—extremely good.
Naturally occurring wormholes are fleeting and unstable.

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A single substance fills the Universe; variations in its expression create all matter, energy, time,
and all other forces.
Drexler doubts that our understanding of Physics will experience the same upheavals it did from
1890-1930. While there are certainly new things to be discovered, our knowledge during the first
part of that earlier period was grossly incomplete. [Perhaps at odds with Kurzweil.]
Nanotechnology will not be affected by new developments in Physics since the cutting edge of
the science deals with extreme environments and highly exotic, unstable particles.
Nanotechnology cannot convert atoms of one type into another. The forces holding the nucleus
together are too strong.
Remember that nuclei strongly repel one another.
Some limits seem clear. The strongest material known—carbyne—will disintegrate under normal
pressures at 4000° C. [What about carbon nanotubules?]
Drexler believes that the natural laws of Physics will eventually limit our technology
permanently, so that at some point, further advancement will be impossible.
Entropy is disorder. Disorder grows as energy is consumed. Since no transference of energy is
ever 100% efficient, some amount is lost as unusable waste—usually in the form of heat.
Entropy will eventually win and prove the ultimate limit on humanity. [Kurzweil disagrees.]
Drexler goes to pains to explain how the entropy of the Universe can increase while it can stay
the same or decrease in a closed system like the Earth.
The Earth’s ability to radiate heat into space will be a limit upon industry.
Spaceships will need surfaces to radiate heat into space.
Nanotechnology has the potential to eliminate all of our resource dependencies.
Space holds all of the resources we could conceivably need.
In 1798, Malthus observed that animal populations increased exponentially but food supplies
only increased linearly. Mathematically, any exponential growth will eventually outpace any
linear growth, leading to an eventual end to the population growth. While Malthus and others
failed to anticipate improvements in agriculture that improved our ability to sustain population
growth, the basic concept that exponential human population growth is ultimately unsustainable
is still sound.
Even with cheap spaceflight, humans will only be able to expand at the speed of light. This
would provide a cubic rate of growth support, which would still be inadequate for feeding an
exponentially growing population. Even space will have its limits.
Drexler believes that since it is natural for all types of Earthly life to spread out to their limits, so
it shall be for intelligent alien life. And since the conditions needed for intelligent life have
existed in other star systems for millions of years before the Earth existed, it is quite probable
that advanced alien life has already evolved and spread across many parts of the Universe.
Drexler wonders whether these aliens would impose a limit upon human growth.
But advanced aliens, aware of the limits imposed by entropy, would certainly make every effort
to conserve resources. Yet everywhere, we see wasted starlight and unorganized dust clouds.
Drexler wonders whether alien life exists, given these realities. [Agrees with Kurzweil.]
Whether aliens exist or not, we should not let them affect our plans if we are uncertain.
Drexler rails against futurists who fail to account for coming technological breakthroughs and
against their negative effects on public opinion.
Warnings of bogus limits discredit the very real notion of limits.
[Drexler clearly believes there may be limits to technology, which contrasts with Kurzweil]

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Chapter 11: Engines of Destruction
Changes to society:
-Assemblers will eliminate the need for international trade
-People will live indefinitely
-Almost all work will be done by nanomachines and A.I.
-A.I. will become much smarter than humans
People will still find purpose in life. How does a runner regard cars or a painter regard cameras?
Synthetic plants with leaves no more efficient than 1980’s solar panels would out-compete
normal plants.
Gray goo scenario.
In a practical sense, nanotech manufacturing could allow countries to build up huge stockpiles of
conventional weapons that their normal industrial base would never have allowed them to create.
A.I. systems designed for battlefield strategy would give their side an edge over enemy forces
commanded by humans.
A state that makes the assembler breakthrough could, if it so desired, accumulate enough military
power in a matter of days to dominate the world. [Hall’s technology “race” analogy.]
If it focused on using its assemblers to build more advanced technology, a state could quickly
gain a huge technological lead over others.
Uncontrolled replicators could destroy the Earth cheaper, easier, and more completely than
atomic weapons.
Nanomachines will allow states to consolidate control over their populaces.
-Omnipresent surveillance of movements and speech could be created
-People could be tranquilized, lobotomized, or otherwise “altered” to conform
With advanced technology, a state could discard all of its citizens and still function.
Genocide would be easy.
An oppressive state must not take the lead in the coming breakthroughs.
Redundancy can bring exponential increases in safety. For instance, say a bridge requires 5
supporting cables to stay up, each cable is designed to last an average of one year, and it takes a
day to replace one cable. A bridge with 6 cables will last an average of 10 years before an
accident involving the simultaneous failure of 2 or more cables occurs. A bridge with ten cables
will last about 10 million years, and a bridge with 15 cables will have a lifespan greater than the
Earth’s.
To ensure true redundancy, different designs and techniques must be used parallel with one
another to complete the same task. This holds true specifically for computers.
Computers can more reliably perform functions when several run in parallel, using different
programs meant to complete the same task. The different results are compared to determine the
most likely answer.
Making systems more reliable increases their cost, bulk, and slowness. But nanotechnology will
simultaneously allow technology to shrink and become more efficient and faster, counteracting
the former effect and allowing us to create technology that is far more reliable than current.
A.I. systems will have room for design diversity and redundancy, making reliability possible.
Drexler proposes that A.I. minds, like human minds, would be composed of different parts that
perform different, discrete functions (sentience would be an emergent property), and that
redundancy could be achieved by making multiples of each part to give a diversity of
interpretations on data.
Drexler thinks that nanotechnology is the only possible counter to uncontrolled assemblers.

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Just as the biological immune system is more complex than a bacterium, the world nanotech
immune system must be more complicated than self-replicating assemblers. This poses a
challenge since a window of time might exist between the advent of the first assemblers and the
creation of an immune system made possible by more advanced technology.
We must have tactics for containing nanotechnology until we learn to control it:
-Make nanotech facilities very secure so no nanomachines can escape
-Make nanomachines in space facilities
-Nanomachines can only reproduce a fixed number of times before dying, like cells
-Nanomachines require rare sources of food or exotic environments that can only exist in the
laboratory
-Make nanomachines with redundant copies of their “DNA” and with strong self-repair
mechanisms to reduce the possibility of mutation
-Program nanomachines to stop working long before any mutations affecting function could
likely accumulate
-Program nanomachines with very precise codes so that a “mutation” is unlikely to produce any
advantageous change and will instead cause the machine to shut down (here is where biological
organisms have an advantage)
To prevent the theft of nanomachines and the independent development of nanomachines by
irresponsible parties, nanomachines in very safe forms should be made available to the public
[But doesn’t Kurzweil say that any nanomachine can be altered to a self-replicating form?]
Limited assemblers are nanomachines programmed to make specific things or to perform
specific duties. Reprogramming them would require special equipment.
One entity will not be able to dominate nanotechnology forever.
Drexler proposes the creation of a worldwide “shield” system meant to block rogue assembler
attack. Government agencies could maintain the lead in defensive technology by putting
insurmountable resources into simulations and planning to devise the best defenses.
Again, the human body shows us that it is possible for a system to defend itself against
replicating invaders.
A.I. designers will give an exponentially large lead in defensive engineering.
So long as the leading institution responsibly uses its technology for good and not evil, the world
will be safe.
It is critical that the U.S. or a responsible transnational agency maintain the lead in technology.

Chapter 12: Strategies and Survival

Global suppression of nanotechnology and A.I. is impossible.
If democracies suspend their research out of fear, dictatorships and deranged groups will take the
lead.
Democracies must recognize this and cannot waste time debating the issue among themselves
while other forces pursue the research.
Advancements in A.I. and nanotech will be incremental, so there will be no clear dividing line on
what constitutes “too much.” Also, since the technologies will impart economic, medical and
military advantages, countries will be unwilling to relinquish them.
Monitoring the technology will prove extremely difficult since nanotech manufacturing facilities
could be relatively small. The same cannot be said for nuclear technology.
Pressure from alert activists will be essential to ensuring public safety.

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The democracies of the world, being the most technologically advanced, will surely develop
nanotech and A.I. first, provided they don’t stop research out of fear. The development process
must be transparent and nonmilitary, or other countries may feel threatened by the impending
breakthroughs and might attack preemptively.
Because the coming breakthroughs in technology themselves empower accelerating
advancement and exponential increases in capabilities, the differences between advanced and
less advanced countries will increase. Whereas today a difference in military technology of even
20 years can still create a situation of military parity, in the future, a lag of even one day might be
fatal. Keeping a military balance will prove increasingly difficult.
International cooperation between adversaries may be the only solution. All developed countries
would work together and share all developments simultaneously.
The use of nanotechnology must be controlled by trustworthy, democratic institutions to gain the
faith of excluded world powers.
Active shields could be built to defend against nanomachines of all sides, and programmed not to
take orders from anyone. The cycle of the arms race could be weakened.
Inspections of shield systems could be allowed to assure all nations of the true nature of the
shields.
Traditional arms control strategies cannot work for nanotech and A.I.
[But all of this hinges on the idea that nanomachines and military A.I.’s would be under the
control of paranoid, emotional, nationalistic human beings. By the time this technology is
available, Strong A.I.’s may have already superceded humans and may be controlling all of the
technology. There is no reason to assume A.I.’s of different national origins would have any
animosity towards one another, nor would they suffer from human faults. Furthermore, I find it
impossible to believe that human beings could ever handle abusing the sort of destructive power
advanced nanotechnology and military A.I. would impart. Even democracies would not trust
each other.]

Chapter 13: Finding the Facts

Society needs better ways to understand technology.
The coming advances pose potentially catastrophic threats.
The general public is unable to intelligently make decisions regarding the development or use of
new technologies.
The government cannot be trusted to handle the new technologies without citizen oversight.
Experts need to inform the public.
Today, vocal scientists usually whore themselves out to different sides of each debate. The public
sees the affiliations to the different interests, and all scientists are discredited as a result.
Scientific journals today are the courts of science in which fact is established through ordered
discourse.
Drexler proposes creating a scientific fact forum that discusses pressing science issues of the day.
Rounds of refereed arguments occur, with a panel of scientist judges scoring each side. Members
of the forum would be chosen fairly and carefully.
The fact forum will make no direct policy recommendations. Its proceedings instead would be
used by the public and the politicians to design policies.
Dr. Arthur Kantrowitz first originated the idea of a public court of scientific inquiry during the
space race when the findings of his expert committee—that the Moon expeditions could have
been completed cheaper and without big rockets by using small rockets to move components into

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space and then assembling the components into a ship—were accepted yet ignored without
explanation. Powerful members of government had vested interests in building a new generation
of big rockets.
Kantrowitz’s idea was never implemented, despite promises to the contrary by Presidents.
The science panel would be used to reach agreements on facts and to determine what was unclear
and needed further research. The panels could meet over the course of several weeks.

Chapter 14: The Network of Knowledge

As technology progresses, the rate of new discoveries will increase, and normal institutions will
not be able to process the new information for the public.
Drexler states the need for the storage of science texts in computer format for ease of searching
and research.
In 1945, Vannevar Bush proposed a “memex” device which stored microfilms and allowed a
person to scan through them and see relationships between different subjects.
Drexler accurately describes the modern Internet and the principles of hypertext, and also
forecasts that music and movies may one day be stored and shared over the Internet just as
commonly as scientific documents.
Drexler describes modern Internet search engines.
Drexler understands how the Internet will create a valuable new forum for public and scientific
discourse, allowing people to exchange and obtain information more quickly and easily.
Drexler foresees the problem of junk on the Internet and of sorting reputable from disreputable
sources.
Drexler understands the value of the Internet in speeding the spread of knowledge and allowing
debate, but he strikes out on a few small assumptions. For one thing, most people still use the
Internet solely for stupid or utilitarian purposes, and there are no well-known forums for
professional debate. Royalties are also rarely paid to contributors.
Drexler understands how the Internet will benefit consumers and improve the economy.
The Internet might be used for evil if the government started using it to track people.
Drexler predicts that the worldwide Internet might not arrive before the assembler and A.I.
breakthroughs!
Drexler correctly predicts that, by 1996, the computer and communication costs will fall low
enough to permit average people to get on the Internet.
The printing press cut the costs of books by a hundred fold, making mass literacy, mass
education, and accelerated technology growth possible.
The Internet will allow people to have access to more information and to get access faster.

Chapter 15: Worlds Enough, and Time

The quest for utopia has consistently led humans to destruction and evil.
A free world is the best option for ensuring happiness and peace.
Technology will lead to decentralization and a shrinkage of government.
Assemblers and A.I. will make complex products without complex organizations that use people
as cogs.
Nanotechnology and Daily Life
-Housecleaning and air purification can be automated and continuous

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-Food of all types will be created without killing animals. The animal rights movement can thus
be expected to strengthen. [What about environmentalism? If people don’t need to grow plants in
nature anymore, won’t there be a movement to dismantle farms and let it return to nature?]
-Drexler joins with Kurzweil in predicting virtual reality for entertainment purposes (tactile
sensations provided by a special suit, direct projections of images onto retinas)
Other Science Fiction Dreams
-Sharing of thoughts and emotions between people through electromagnetic signals
-Extreme alteration of the human form
-Time travel in the form of cryonic biostasis
Technology will promise wealth, freedom and living space in excess of anything anyone knows
today.
Immortality is impossible, but indefinite life is possible.
Drexler reiterates the need for sound and open management of developing technologies.
Drexler, like Kurzweil and Fukuyama, foresees an increase in Luddite activity
Public education is key to properly guiding the growth of technology.

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