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Home > Interviews > Wil McCarthy - June 2003
Quantum dots, programmable matter, and wellstone Interview with Author Wil McCarthy - June 2003
By Rocky Rawstern
Editor Nanotechnology Now
I recently had the distinct pleasure to interview
one of my favorite authors, Wil McCarthy. Upon completing three of his
latest books - two sci-fi and one work of non-fiction - I realized that
many of our readers would probably enjoy his ponderings as much as I.
The questions for this interview stem from my own interest in
programmable matter, and the awe-inspiring possibilities raised by Wil
in his book HACKING MATTER. The side-bar contains a few quotes from HM.
Can
you give our readers a brief explanation of "artificial atoms" and
"quantum dots," and how they - when produced en mass - can create
"programmable matter"?
A quantum dot is a device
which traps electrons in a very small region of space, forcing them to
behave like tiny standing waves, just as they do in atoms. An
"artificial atom" is a cloud of electrons trapped in this way. Although
it has no nucleus of its own, the artificial atom behaves in many ways
like a real atom does. Producing large numbers of artificial atoms
inside a bulk material, such as a semiconductor, will alter its
properties dramatically so that, for example, it can be made to appear
and behave like a metal, or an insulator. The material's color,
transparency, reflectance, thermal and magnetic properties can also be
altered, in real time.
How do the quantum dots that you write about
differ from the nanocrystals with the same name, which are being used
as "optical beacons"?
"Quantum dot" is a word like
"switch," which describes a lot of different devices which look very
different but fundamentally do the same thing. These semiconductor
nanocrystals are a good way of trapping electrons, because chemists can
grow them very precisely. In a solution you may have moles(1) of this
stuff, really enormous numbers of particles, which are almost exactly
the same size and shape. People like them for their optical properties:
they drink in white light and emit a single bright color. They're
finding uses in biology to replace fluorescent dyes, and as optical
elements of lasers and such. It may be possible to create very, very
tiny lasers which could, for example, perform surgery inside a living
cell.
But that's only one type of quantum dot. You can also
trap huge numbers of electrons on the surface of a metallic particle,
where their properties will be rather different. Fullerenes and
nanotubes also hold great promise, but my favorite sort of quantum dot
uses electric fields to confine the electrons in a layered
semiconductor called a quantum well. This is a neat trick, because by
adjusting the voltage on a set of metal electrodes you can precisely
control the number of electrons trapped in the dot, which is equivalent
to changing the atomic number of the artificial atom. This is where the
term "programmable" comes in, because it's quite feasible to control
these properties with fairly simple microelectronics, to produce atoms
and materials which could not exist in nature.
How does your definition of "programmable matter" differ from that used by a cellular automatist?
A cellular automaton is a type of computer program which models a
region of programmable "cells" whose behavior is dependent on the
states of neighboring cells. This can be really useful for simulating
phenomena like fluid mechanics, and one advantage it has over
real-world testing is that the properties of a given cell -- its
virtual "substance" -- can be changed at a whim. The term "programmable
matter" is sometimes used to describe these simulations, but of course
this "matter" is symbolic and has no existence outside of a computer
screen. It's virtual programmable matter.
However, programmable solids based on electrostatic quantum dots are
possible, and to a very limited extent they exist right now, in
laboratories all over the world. This is not a virtual or theoretical
exercise -- the material properties of the solid really do change.
Do you foresee an integration of quantum dot
technology with molecular manufacturing, aka nanotechnology or
molecular nanotechnology (MNT)? Or are they too far divergent?
To exhibit atom-like behavior at room temperature, quantum dots need to
confine electrons in a region of 20 nanometers or less, so any useful
programmable material would really need to be assembled with nanometer
precision or better. So you do need some very sophisticated
manufacturing techniques, and MNT is a good candidate, along with "atom
optics" which can beam atoms onto a surface en masse, with incredible
precision. Programmable matter exists in the solid state, with no
moving parts except electrons and photons, whereas MNT is all about
tiny machinery, so yes, they're very different technologies which just
happen to exist on the same scale. But they could be very
complementary. Nanomachines which incorporate programmable atoms might
be among the most powerful and versatile devices we could ever create.
Integration with microtechnology, including J. Storrs Hall's "utility fog," is another strong possibility.
In
your opinion, why has there been so little press coverage of quantum
dots, aside from the medical (optical beacon) applications?
Good question! The implications of this field are enormous, and fairly
obvious to anyone who sits through even a cursory explanation, but
almost no one in the press is paying attention. A few science fiction
writers are following my lead today, moving in to explore this
technology in tentative ways, but the real-world stories are published
mainly in very technical journals, not glossy magazines or newspapers. WIRED has been fairly progressive in this area, and IEEE Spectrum has recently picked up the torch and seems to be running with it. But for Newsweek and Time it might take a while.
Can you give our readers a brief explanation of "wellstone"?
Well, I'm an engineer as well as a writer, and when I first started
hearing about quantum dots it struck me right away that programmable
matter was the ultimate application. So my busniess partner and I
started brainstorming, and we came up with a method for controlling
quantum dots inside a bulk solid. Basically, you put the quantum dots
on the surfaces of very small fibers, and then weave the fibers
together. That's wellstone, so called because it's made of quantum
wells and silicon, or stone. We filed a patent on the idea and have
already turned away two venture capitalists, because their money and
time horizons were too small. But our company, Galileo Systems, is
already doing aerospace research for the U.S. government, and we're
working our way toward research dollars in this area as well. The main
obstacle is the sheer amazingness of our claims; no matter how
carefully we phrase things, you can see these bureaucrats' jaws drop,
or their arms cross in disbelief. But little by little we're getting
there, as information becomes more widely available, less shockingly
novel.
What are some of the remaining significant technical hurdles that must be addressed prior to the creation of wellstone?
The greatest bottleneck is in manufacturing -- the tolerances are just
not achievable in three dimensions right now -- but there are
theoretical issues that need to be ironed out as well. Between the
realm of cells and atoms, nobody fully understands how materials
behave. There are lots of surprises in store, and our designs will
undoubtedly need to be tweaked along the way. But with determination,
we can probably build something close to a wellstone fiber within 10
years.
Since the publication of your book HACKING
MATTER have you heard of any research that indicates that your
speculations are still on track?
The worst thing anyone has said about HACKING MATTER
is that some of its speculations can't be proven at this time. Which is
true. This is a hallmark of any new field, including nanotechnology.
But programmable matter's underlying principles are on very solid
footing, and the physicists profiled in the book have weighed in their
cautious support. Some applications have yet to be demonstrated in the
lab, but there's nothing obviously wrong with them.
What inspired you to write the science fiction
novels THE WELLSTONE and THE COLLAPSIUM, and the novella ONCE UPON A
MATTER CRUSHED?
Do you have to ask? With this sort
of cool future technology at hand, completely unxplored by the field of
science fiction? I saw my chance to do something really new and
inventive, and jumped at it. It was only later that I began pursuing it
seriously as a scientific endeavor, and even that was mainly out of
frustration. If someone else had moved forward with the idea, I'd've
probably been content to watch from the sidelnes.
Technological hurdles aside, when/if science
reaches the point where wellstone (or some equivalent) is practical and
inexpensive to manufacture, what do you see as some of the "life style"
implications?
Read HACKING MATTER, or my
science fiction books on the subject. The implications touch on nearly
every aspect of our lives, from clothing to transportation to vehicles
to housing, and are just too huge to address in a space like this. The
programmable house, with its heat pumps and solar collectors, its
anywhere stovetops and moving, shape-changing windows, takes up a whole
chapter all by itself, and barely scratches the surface.
Where would you like to be in 2020, and what would you like to be doing?
Where would I like to be?
Looking out at the rings of Saturn from my private space yacht, sipping
bourbon from a squeeze bulb and playing footsie with my wife. I'll be
54 at the time, though, which may be too young for retirement,
especially if some of these anti-aging therapies start working out. So
maybe we'll push that one off to 2030. |
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"A
thin disc of wellstone inside the eye - or a contact lens on the eye's
surface - could photodarken to protect the retina against bright lights
(even extremely sudden ones). It could also act as a permanent "head-up
display," projecting pre-lensed holographic information onto the
retina. Piezoelectric wellstone in the ear could serve as both a
receiver and a generator of sound waves."
"This point bears repeating: the electrons trapped
in a quantum dot will arrange themselves as though they were part of an
atom, even though there's no atomic nucleus for them to surround. Which
atom they resemble depends on the number of excess electrons trapped
inside the dot. Amazing, right? If you're not amazed, go back and read
the last four paragraphs again. I'll wait."
"A wellstone TV might look less like a moving
picture and more like a window into a real, three-dimensional space.
You could paste these all over the inside of your house, making it look
(from the inside) as though you were living in Tahiti, or Antarctica,
or on the red-hot surface of the planet Mercury."
"If transparent wellstone were able to take on a
very low index of refraction, its optical characteristics would
resemble those of air or vacuum. This is true
invisibility, and it could result in aircraft that did not show up on
any electromagnetic scanners of any kind, including the human eye."
"If programmable matter can be made to work, not
only is it a powerful technology in is own right, providing
hypercomputers and dazzling optics and an unimaginable wealth of new
materials - it also has an "instant gratification" quality that
eliminates many of the inconveniences of today's world. New materials
can be invented and examined at any time, without the need to mine or
manufacture or calculate anything. New devices can simply be specified
and tried - eliminating the pesky steps of design iteration, parts and
materials acquisition, prototyping and production. Matter becomes
something akin to software - infinitely malleable and precisely
obedient. In the future, manufacturing may join mathematics and
software as an enterprise where true, literal perfection is not only
possible but easy and quick. This makes the technology of programmable
matter a huge enabler and catalyst for technology development in other
areas."
"Undoubtedly, there are hard physical limits on
what human beings can accomplish through the tweaking of matter's
building blocks. But I, for one, find it exciting and reassuring that
we're nowhere near these limits. In fact, we can't even guess where
they are. Until we hear differently, the major restriction is our own
feeble imagination."
"(But) with programmable matter at our command, we
may find it trivial to construct much lighter and more capable
spacecraft, even as we wallow in an energy glut of unprecedented
proportion. Effectively, we'd all be multibillionaires, with the
economic and industrial clout of entire twentieth-century nations at
our command."
"If programmable matter is indeed a practical goal,
there is scarcely a field of human endeavor that won't benefit in some
way." |
An occasional aerospace engineer, SF writer Wil McCarthy is currently a
contributing editor for Wired magazine and the science columnist for
the SciFi channel. His novels include the New York Times Notable BLOOM, Nebula Nominee THE COLLAPSIUM, and most recently, THE WELLSTONE. His nonfiction book, HACKING MATTER,
concerns the emerging science of programmable materials, and was a #4
bestseller on Amazon.com and a selection of the Library of Science Book
Club, the Science Fiction Book Club, and How To Media (aka Science News
Books). |
Wil McCarthy standing next to a Titan II Stage 2 rocket body. Click to enlarge. |
(1) 6.23 X 1023 molecules
Click on the image of the book or the title to see reviews, or to buy.
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