Just a rambling...

You see, last semester I couldn't get my physics 121 teacher to buy Survivor's Bernoulli effect hovercraft idea. That was a little hard on me.

But, just now, I was talking to my physics 122 teacher about how you should be able to generate electricity by pumping water up a hill when the moon was up, then letting it turn your generators on the way down when the moon was down. I mean, shouldn't that sort of thing work? But he pointed out that there's a high tide both when the moon is directly overhead, as well as when the moon is on the opposite side of the earth, and then told me that he would think about it a little more.

It could be fun, just as a test of your persuasive argumentative skills (and maybe a little of your teacher's ability).

Anyway, that's not science fiction. That's real life science. Not that real life science doesn't have any place in our stories, but it's more fun to think up FTL drives and antimatter implosion powerplants. My favorite is an artificial gravitational singularity, with an energy topography that acts like a black hole on matter but then releases the energy as gravity across a cycliod inverted in a torus, producing polerized gravity (so matter is pushed away from one side and pulled towards the other). It works as an energy source, a drive system, and an artificial gravity system all in one .

That's the kind of thing I'm talking about. What happens at the speed of light, the impact of guaranteed minimum subsistence on an economy, the best way to accelerate a planet so as to escape a dying sun, tactical models for interplanetary warfare, you know, the really big questions.

Are we not the big wheels? Do we not seek to answer the big questions?

On the other hand, if we don't get feedback on our ideas early in the storytelling process, tragedy can result.

For instance, I read a story that centered around a nanomachine that was designed to create a sort of living dress on an infected individual. Now there were a number of interesting errors that the author made in talking about technology.

First, these dresses are woven from an ultrafine fiber optic plastic, with high light transmission properties. The author asserts that this would mean that the dress would be completely transparent unless an opaque pigment was used. This is not true. The property of light transmission is important in a fiber optic material, but just as important is the index of refraction and thus the degree of total internal reflection. An ultrafine fiber optic material, if woven into a fabric, would be purest white, not transparent (on the other hand, it would be possible to make it marginally tranparent by getting it wet, al la wet tee shirt, but that might not be possible if the fiber was also water repellent).

Secondly, the dress so woven was described as bulky and hot. If the weave was dense enough to be bulky and hot, then not even a dousing with water or other liquid would produce transparency (even granted that the fiber wasn't water repellent). More importantly, it would have to be a fairly heavy fabric. Optical fibers tend to be smooth and round, which would tend to reduce their water absorbency and insulation value, both important factors in making a fabric 'hot' or stuffy. Ultrafine optical fibers should be very flexible, so such a fabric would more likely be silky unless it was very heavy.

Okay, this is really an extension of the second point. Or a conclusion. See, the dress so composed is described as being very heavy, so I'm sort of confirming the story on this point rather than anything else. But the material for the fiber is supposed to be drawn from carbon, hydrogen, oxygen, and nitrogen present in the air. Also, the nanomachines responsible are supposed to be able to make an entire dress in a single night, and repair damage to the dress faster than a trained seamstress can cut the dress apart. Just making the dress from air would require a significant energy input, and repairing the dress while a person is trying to cut it apart would have to take even more energy. There is no plausible mechanism that explains where this energy is coming from.

The manufacture of the fibers is easy enough to believe, but weaving them into a dress? That would be an quantum leap in nanorobotic control and intelligence. Not to mention the instantaneous detection and repair of damage. But the design of the nanomachines is described by 'experts' in the story as unimaginative and clumsy. That would be my third point, that this totally miraculous advance is the main point of the story, and is characterized as a simpleminded 'adaptation' of an existing nanomachine that manufactured optical fibers (presumably in a straight line).

Forth, because the author is under the mistaken impression that the fabric would be transparent, the nanomachines also manufacture an interference pigment. This wouldn't be so hard, it's more plausible than any of the rest of the story. But the color of the pigment is described as a 'dull, putrid, gray green'. Interference pigments are invariably iridescent in quality and reflect pure colors. It is possible to produce a 'gray green' by mixing interference pigments, but it is impossible to produce a 'dull, putrid' color at all. Believe me, I've fooled with the stuff. Getting a 'gray green' takes about four or five pigments while a brillient iridescent green takes only one pigment.

Fifth, the protagonist comes up with a plan to embarrass a bunch of people wearing these dresses by exposing them to a color of light that will neutralize the interference pigment and turn the dresses totally transparent. Now of course, even without the pigment, the dresses would be white, not transparent (and if they were as heavy as described, not even a dousing would make them even partially, let alone totally transparent). But the main point is, filtering light to 'exclude' a color only works on selective reflection pigments, interference colors produce color by interference, so filtering light doesn't neutralize them. Even in the case of a normal pigment, filtering light can make it appear black, but not transparent.

Number five may seem like a small quibble, but it's not. The prank was the major climactic action of the story, just as the dress was the major premise. And both were completely scientifically impossible, even by my standards (namely, nothing is to be excluded from possibility until it is proven impossible). I mean, the filtered light thing wouldn't have worked if any of the known laws of physics held. By comparison, the dress making nanomachines were only improbable.

So what am I saying? Just that talking about science that we want to use can save us from this sort of embarressment (this story that I mentioned was actually published in a magazine with national circulation, so it'll follow the author forever). And on the more positive side, talking about ideas on the forum can spark our creativity even as it acts as a safeguard against total idiocy. So it's good in lots of ways

Also, bacteria are difficult to program. Can you imagine encoding the manufacturing instructions for a microchip of today's complexity in DNA? I suppose it might be possible to create a sort of "DNA compiler" and program bacteria in a sort of bacteria assembly language, but can you imagine debugging your software that way?

And of course, perfecting the little buggers would cost more money and take more time than programming a nanorobotic arm. In the end, even if bacteria can perform all the functions required for moleculer manufacturing, a machine would be a more practical solution.

I can see bacteria used effectively in chemical synthesis and medical applications, but there is a dry side that needs a machine. And in fact, once we perfect a robotic arm capable of molecular posistioning (and thus, self-replication), it may be easier to build specialised nanobots for medical purposes.

I think that there is a basic flaw in the way that this Robert guy views nanomachine design. He seems to think in terms of seperation of components rather than in terms of the machine as a whole.

Anyway, in my view bacteria would be very bad at manufacturing, because they'd have to:
1) Know how
2) Work in absolute tandem with millions of other bacteria
3) Be able to deposite substances with atomic precision.

Crap, I think my high school education is showing through. How DO bacteria move stuff about and into place precisely, for tasks such as the repair of a membrane, or even DNA? If they can do that, I suppose they have the precision required for molecular manufacturing. But then do they have the necessary external awareness?

It's times like these that I wish I'd quit school much earlier than I did. All those worksheets in Biology class, and they never bothered to tell me anything that really mattered.

Anyway, my questions are largely rhetorical. I know where to find the answers; I'll just have to work it into my reading.

The bacteria do not have to think, they only have to respond to environmental variables in a manner that is dictated by their organic structure. One simple way of controlling them is to use a 'find and replace' approach. You develop a couple of types of bacteria that are willing to exchange one type of molocule (say, a jello molecule) in exchange for another molocule (like a diamondic fullerine) and make a shape out of the jello. Let the bacteria at it, and in a jiffy they replace all the jello with a diamondic fullerine matrix. Cool, eh? Now that's just a very simple example.

Anyway, as for how bacteria function, they do it using a variety of organic molecules that 'fit' together in complex ways, self assembling in some cases, controled by complex feedback loops in others. When bacteria function as a group, they relate to each other by environment rather than by plan. Take the case of slime molds. All the bacteria in a slime mold are indistinguishable, and there is no method of communication. They simply respond by order of environmental factors on each cell, but the 'mold' as a whole appears to exhibit the characteristics that we associate with more complex forms of life.

So you see, there really is no problem with knowledge, coordination, or precision. The first is a naive concept to apply to machines anyway, the second is a demonstrated capability of bacteria, and the last is an essential function of survival for bacteria.

Which isn't to say that bacteria are just naturally going to do what we want. That's where the engineering comes into play.

Bacteria can be used for a lot of things already, though. Already they can be used to manufacture most naturally occurring organic substances. They are also useful for gathering certain other molecules and even sorting them. For instance, the process of manufacturing fullerines at present relies on crude 'scattershot' methods that manufacture some of the desired chemical, but also a fair amount of other material. Bacteria could be designed to sort out the desired molecule, ingest it, then 'swarm' to an chemical cue and deposit or exchange it.

It (the bacteria) seems like a jolly good idea, and we seem to be in agreement that mechanical nanomachines will exist eventually.

There are limitations to the control scheme you describe that make bacteria inappropriate for some applications.

For example, have you ever heard the slogan "matter will become software"? The idea is to sell a "nanobox" that should, given the materials, be able to make anything that fits within it. So, you could download the instructions to make a cell phone, put in a few sheets of material, and in a few minutes out would pop a cell phone. Bacteria are unsuitable for this application because they aren't reprogrammable.

Another is precision fabrication, such as making a computational device. Bacteria could build the semiconductor, but they could not (using environmental control) lay the impurities in the right places, using the minimum amount of dopant atoms per gate. If the pattern could be laid for the bacteria to exchange proper materials, then the proper materials could be laid in the first place.

In fact, one major hurdle is the sheer amount of data such an untertaking would require.

I'm going to admit that I have not read extensively on this subject. Most of my conceptions of nanofabrication come from http://www.zyvex.com/nano, an area which (inexplicably) is not linked from their main site.

It's always dangerous to talk of what bacteria can't do, because they have been discovered to do almost anything that one can imagine nanomachines doing. There are bacteria that could conceivably live and work inside your car's engine, although persuading them to do anything useful has not yet been seriously contemplated. Bacteria can produce complex patterns by relational dynamics, which can be determined by both genetic and exogenic design. In fact, they can do anything that nanomachines can do, because they are nanomachines. How do you think that anyone ever came up with the idea of nanomachines except by seeing what bacteria can do?

Anyway, it's never likely to be effective to program the macrostructure into the nanomachines. We already have fabrication techiques (including three dimensional printing, a hot bio-tech item) to set the macro- and micro-structure of elements, and using micromachines to handle the microstructure and millistructure is only a matter of developing cheaper micromachine replication (which will probably be achieved by a combination of macro- and nano- machinery, ie. a very precise, multiple head 3D printer could 'sketch' a large number of micromachines, which would then be 'fleshed out' by nanomachines. Then, to build a larger object, you would have a larger, less precise, single head 3D printer that would 'sketch' out a design, which would then be converted to a 'trace' by nanomachines, then the 'trace' would be worked on by micromachines to become a 'draft', then the nanos would finish it.

As complicated as that may seem, it's really quite simple to 'hand' tasks between the various scales.

Just as an added note, medical technology is the one area that nanobots (in the sense of being entirely inorganic compositions that have central programmable processors) are likely to dominate. I'd sure feel more comfortable with nanobots that don't have a bacteria genesis if it came down to injecting me with a population of tiny bugs But for other areas, where cost is a significant factor, bacteria and virus-like machines (one thing that bacteria could be very good at is manufacturing virus-like machines, and if a suitable 'port' existed for ejecting such a device could be created (which shouldn't be hard, similar ports exist that allow bacteria to ingest material), then bacteria could be given the ability to 'make' tools for themselves or for a different population.

Anyway, the continuum that engineered bacteria represents may stretch much farther than was supposed possible even a few years ago. Bacteria have been discovered doing all kinds of things in all kinds of conditions. They have been discovered with several different types of metabolic engines and manipulating (with characteristic molecular precision) most known elements. And they have the potential to make nanotechnology dead 'ard and even deader cheap.

But for your purposes, it makes no real difference. Engineered microbes are a type of nanotechnology, and always have been recognized as such. In practical use, there is no ready distinction between engineered microbes and scratch engineered nanomachines, since all nanomachines are and for a long time to come will be inspired and informed by microbes.

As for a two way brain interface, did you hear about the blind guy that now has an artificial eye? They implanted the optical area of his brain with micro electrodes, and now he can see (sort of, the resolution is apparently really crappy, but their planning to push it up by several orders of magnitude) for the first time since birth. They also can plug him into any adapted video feed, so it's like having a moniter built right onto his brain.

There has been a lot of prosthetics work on the other side, too. They now have a variety of ways to 'train' a system of electrodes to interpret nervous system functions, and some work has even been done with monitering the brain, although 'mind' reading is still out of reach. Still, with what is known now, it is possible to put all the i/o functions inside a person's cranium. Virtual mouse, display, audio, keyboard, even things like visual scanning and aural sampling should (repeat should) be possible, along with similar functions for all the other senses.

You'd prefer injection with bots to buggers? I wouldn't care. Your body disposes of unwanted organic material, so it all ends up out the tubes anyway.

That's really cool, the eye. In this case, I don't want the receiver of the implant to have to mess with something as elaborate as electrodes implanted throughout the brain. Nor do I want to have external ports or anything messy like that. I think I've settled on a small interface in the spinal cord, near the base of the brain stem, that would be built by nanomachines and controlled by radio.

As for "reading" and "writing", for my purposes there's no need to interpret a person's abstract cognition (no letter dictation), but is more sensory and unconscious-desire based, things you say are possible even now. As for writing, I need not actually store anything in the brain, I merely nead a way to send it signals, and the mind will store them if it sees fit.

The main difficulty in a spinal cord interface, as I see it, is persuading the brain to send signals in that direction that it doesn't ordinarily send. But that's really dependent on how the brain computes, which is unknown enough at this point that I think I'm safe.

The main hurdle for 'designer' bugs was that we'd have to test endless numbers of 'engineered' proteins and solve their structures, previously a difficult art form. Now, with the advent of computers cabable of 'solving' protein folding, we can just create 'engineered' proteins willy nilly.

I wouldn't want them in my body for a couple of reasons. Number one, it would be really irresponsible to create a baterial strain that was invisible to the human immune system, so we won't even consider that. Which means that the bacteria would be operating in the most hostile of environments, with my body constantly trying to kill them off. Number two, the body is a very molecularly complex environment, and there's a good chance that 'engineered' bacteria would have just as much trouble with their control systems as scratch built 'nanobots'. Number three, some or most 'engineered' proteins are likely to be toxic or carcinogenic in one way or another, since they would be more chemically complex and active than the molecules used in 'nanobots'. And number four, I think that if someone's going to inject me with some kind of bugs and charge me ten thousand dollars, they might as well be the most expensive little bugs available

Anyway, to get visual input, you need to get the signal into the optical pathway, so the spinal cord wouldn't work. You could use nanotubual fullerine compounds to reach the optical nerve or optical centers in the brain, though. I'm not sure, but I think that the guy the implanted was congenitally blind or something, or that his optical nerve was damaged. Same goes for voice input, it doesn't go through the spinal cord either. Output could be subvocalizations, which should be easier for a computer to learn to process than even ordinary voice recognition. The implant would just send a stream of data describing what your tongue was up too. On the other hand, they've developed a system for quadraplegics that uses a 'visual mouse', where an electrode attached to the skull can tell what part of a screen the person is looking at (this worked by flashing different portions of the screen at different frequencies, and determining which frequency they were actually looking at). It would be difficult to adapt that system to a display that was input directly into the neural path already, but not impossible by any means. That technology is already several years old. It may be possible to shrink the response time to the point that a person could 'type' on a virtual keyboard inside their heads faster than an expert typist (on a normal keyboard, of course).

As for communication with hardware outside your head, I think that I would choose an optical port, possibly secured to a titanium bone implant. A radio link has...vunerabilities to many common types of interferance, and is not so easy to shield. Light energy, particularly infrared, is very safe and can handle a high bandwidth of communication.

But some form of spinal cord implant could work, at least for output and tactile or proprioceptive input. But visual input would be hard. Have you ever tried to 'watch' TV by tuning a radio to the 'picture' band of the station you wanted to 'watch'? I can tell you that it just doesn't work. Vision is one of our most sophisicated senses, and I don't think that most people (or even any) could learn to accept other sensory input and interpret it as detailed visual encoding. The problem goes the other way, too. Have you ever tried to 'listen' to a sound by looking at it's wave form?

The neuron-machine interface is a fascinating topic. We have the technology now to stimulate neurons with probes responding to signals that generated from other neurons. Given that, it is really only a matter of time before medical science finds fixes for various spinal, brain or Peripheral NS injuries and the consequent loss of functionality. There's already a machine that gives limited perception of light and dark to previously sighted people by direct stimulation of the visual cortex.

As for nanomachines, I predict this technology will be used for things like clearing up clogged arteries and repairing stroke damage (or at least clearing out the dead cells so that healing is faster) in the very near future. I give it 10 years before we're in the testing phase, at most. Another targeted use might be in attacking certain types of cancers and/or as a supplement to the immune system.

I'm hoping one day to be able to photosynthesize. I wouldn't mind having a green tinge and "bushy" hair if it meant I didn't have to worry about what to eat. And, I could produce my own oxygen from my own C02. Think of the endless joy of respiration!

Other uses for engineered bacteria that are here or on the horizon: Environmental cleanup. They already have oil-eating bacteria. If they can eat oil, they could be made to eat plastic. That means we could set them loose in landfills and eliminate the worst of the non-biodegradable stuff. The problem is containment. Wouldn't want to have plastic eating bacteria loose in the average home. My preferred solution to this is temperature sensativity. You create bacteria that can only operate in environments in excess of 120 degrees Celsius (or maybe higher). Then, you coat the land fill with them, and raise the temperature to the critical level. As they work, they generate more heat until the fuel is all used up, then they die.

Another alternative is making them light sensitive or, like the Jurassic Park lyseine contingency, make them lacking in a rarely occuring nutrient (e.g., not lyseine) and then when you want them to die, you take away that nutrient so they can't reproduce.

A more far fetched notion is reduction of atomic waste through use of genetically engineered organisms. Basically, this limited alchemy. You are removing electrons from matter through a digestion process -- the electron transport chain. What we need is a way to do the same with protons and neutrons. If we could figure that out, we could turn all our uranium into lead and all our lead into gold.

But yes, obviously it would be foolish to ignore or disregard containment and cleanup issues, or to rely on a single "foolproof" failsafe system. One thing that would be a nice counterpart to artificial enzyme dependancy is specific engineered toxicity, making the organism susceptable to an artificial toxin specific to the engineered organism. If the toxin were boidegradable and nontoxic to natural organisms, then it could be used liberally in the event of a spill, but leave no residue itself. And since the bacteria wouldn't normally encounter it, they would have no "advantage lever" to cause them to become resistent, particularly if the engineered suscepability were tied to some improved aspect of their metabolism or cellular structure.

Also, in a slightly more exotic direction, I was thinking about using a field effect generated from a point fixed to the cranium, and targeted towards the brain so that nothing would be physically impacting inside the dura mater itself. I think that the inherent benfits that approach offers in terms of safety and ease of repair make it worth pursuing despite the fact that we don't yet have a feasible technology for carrying it out. Also, such a system need not be implanted at all, it could be worn like a headset (unless it were important to have the sensor/feild emitters inside the cranium, which is possible). Thus there need be no implant at all, the interface would be free and could be built into third party appliances. On the other hand, if security and concealment were high priority, then an implant might be favored even if it offerred no other significant advantages.

I think that's sort of an interesting thought. How about an implanted 'key' or identifier/signal conduit that would allow people access to different devices or applications on the same device? So would there be some people that had illegal 'master keys' that could mimic the signal processing functions of other keys? And what would that involve? I would think that you would need to actually physically examine the original device if there were any kind of advanced crytography involved in making the keys truely unique and difficult to forge. So to steal someone's identity you would need to physically meet them and figure out how to examine their implant without giving yourself away.

Interrogating, or getting some examples of the encryption of the implant, would be easy, but that wouldn't help against a really advanced encryption. Besides, you could probably pull that off without ever meeting the person. You would need some kind of physical scan that could resolve the micro/nano structure of the device, without activating it or causing interference with its operation (since the implantee would probably notice if his implant started outputting into his aural or visual centers). So how long would that take? An hour? Maybe a day?

Anyway, can you "stimulate" nuerons with a pulse of light? If I know you (not that I do), the answer is yea.

To get back to an older portion of the discussion, your take on an interface located on the spinal cord seems backwards to me. The usefulness (and plausibillity) of such an interface depends on the nuerocomputational model, and our abillity to decipher and imitate it. The work in this field, from what I've read, is still extremely theoretical. Thus for the present, I should be safe taking liberties.

There shouldn't be any problem on the upstream with such an interface. There is no doubt that the connections exist; it's a matter of pursuading the brain to "forward" the signal to the appropriate places, which depends on the nature of the brain's computational model.

Downstream, though, is more difficult. The brain does not ordinarily send most signals to the spinal cord, since there has hitherto been no reason for them to leave the brain. And if we're not putting anything in the brain itself, there's nothing in there to initiate a signal headed in that direction. It may be possible to pursuade the brain to do it through training and other such adaptive methods.

I don't think a field effect solution is viable, simply because that way you can't "read" from the inside the brain. In order to determine the origin of internal emissions, you would need a coherent signal for comparison.

That, and projecting the field with accuracy would be extremely complex to implement, especially if you wish to influence two areas at different depths on the same Z axis at once.

About securing your "intellectual property" (:P). The trouble with encryption is that for any device to interpret your signals correctly, it must also have the key. This might be overcome be requiring the implantee to authorize all transmissions of the key, and set up a notification system that would tell you when something tried to get your key without asking for it legitimately. Interception of the signal would be prevented (or made extremely difficult) by sending it encrypted with a decryption program that would require a unique device ID to perform the decryption. Anything that failed to provide a correct ID would cause the program destroy itself.

As for an imaging technology capable of resolving the nanostructure, is there any technology, developing or theoretical, that has that potential? The only one I can think of off-hand is antiproton imaging, but such a system would be room-sized (there's no way to collapse it; you need detectors on all sides) and could be too destructive for circuitry. If a circuit is constructed to use the minimum of dopant atoms per gate, the annihilation of one of them would kill the circuit.

Anyway, not that an interface tapping into the spine is impossible, just that there are difficulties because of the nature of what the spinal cord is designed to do and not do. Our spinal cords do not carry visual or auditory information, the two input paths that most of us find most useful for working with a computer. Nor is proprioception well understood, and much, if not most, of the information that the spinal cord delivers to the brain is proprioceptive. We don't understand how it works, or even if there is a consistent model for it. Also, a malfunction in the area of the spinal cord may well be fatal or at least crippling, whereas the brain itself is very resistent to such damage (this is why all practical technological advance in neural interfaces has concentrated on the brain itself so far). So I have three objections, theoretical, because the spinal cord is poorly suited by it's fundamental nature, practical, because the spinal cord is more delicate and less (forgive me) dispensable than the part of the brain we consider, and historical, because there are brain implanted interfaces and plans for developing them, while there are no such existing devices for the spinal cord.

That doesn't mean that the spinal cord can't be used for an interface point, it just means that anyone that is well versed in the state of the art with regard to neural interfaces would be skeptical of a story in which you say that the interface should be in the spine. It seems unworkable to anyone that is expert in the actual technology (not that I'm an expert).

Field effects could work for some things, in fact, they are already very useful for finding out what is going on inside the brain (although I don't know that you would want to say right off that an MRI can fit in an implant on the back of your skull). Sending useful information back into the brain, now that is hard. I don't know how to do it. The main benefit is one of safety and ease of use, because nothing actually need be implanted for such a system to work. That would be such a large benefit that there will probably be some work done in that direction, even though we do not yet know that it can work. The main problem is that sending information back into the brain may require...well, it is a difficult problem.

See, currently, we have discovered that you can encrypt something using one number that is very difficult to decrypt without using two other numbers that are mathmatically implied by the first number. You can thus 'lock' your code with one key, and you need a different key to 'unlock' the message. You give everyone the 'locking' key, and keep the 'unlocking' key to yourself. Because the system is based on natural number factorization, and the larger the prime number factors are the more difficult it is to factorize, and there is an infinite supply of ever higher prime numbers, the system can be made arbitrarilly hard to crack. So we already have a suitable coding system. Anyone can code a message so that only the intended recipient can read it, unless someone wants to spend years and years factorizing some million digit number into two thousand digit primes. But as always, additional safeguards are possible. Though there is no way to guard against someone copying the original program an indefinite number of times and then using the copies to get as many tries as they wanted at the decryption code. I would prefer a second level of true random signal addition, or even a 'misdirection' cypher, so that even when the message was technically decrypted you wouldn't know what part was the message. But both of those ideas have the disadvantage relative to the factorization system, because they are both 'single key', in that if you know how to encrypt, then you know how to decrypt.

Right now there are a couple of ways to scan a nanostructure, non of which could be used on a person without their knowledge. But who knows. Perhaps if you let a dose of nanobots loose in their body, with the ability to record what they 'saw' then you could extract them and get a good scan. That might work, unless they had a 'nanotrap' to tell them if anyone was trying that, a part of the implant that nanos could get into but couldn't get out of. In any case, I think that it might well be a 'race' that the encrypters would always have the upper hand in, as has ever been true. It is always harder to crack a code than to devise it (at least, the codes that we see in history, but then, perhaps only the 'good' codes ever got used a lot ).

Anyway, there is probably some advantage that you want to get from using a spinal cord interface that I'm not aware of. I just can't imagine what it might be.

On another subject altogether, why is it that flying antigravity boots and harnesses are both very common in fiction, but a handgrip isn't?

The main problem is that they undermine the chief advantage of a man on foot, which is stealth. On the other hand, if they could push the output up to 40 mph, then it wouldn't matter that much. That would be fast enough to obviate the disadvantage of being noisy by putting the user in another class of mobility altogether.

I'm willing to bet that if you built the tibia control mechanism and pedial lever out of composites, you could bring the empty weight of the device down to about that of a normal combat boot. Then the only overhead would be fuel (well, and you would need a mechanism to fold the pedial lever into a inactive position, but I can think of a couple of ways to do that). And if you extended the tibial control up to the knee, I'll bet that speeds of over 60 mph should be theoretically attainable (of course, then there's the question of whether anyone would really want to risk going that fast on foot ).

quote:

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Since the beginning of time, man has yearned to destroy the Sun!

I shall do the next best thing...

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Today was a sunny, only moderately chilly day.

And I was thinking, as I talked to Masdibar, about how nice it would be if the sun weren't quite so bright.

Of course, I've never found much support among the apparently heliotropic human race for the idea that the sun should be blotted out, but my musings were turned to Al Gore and the envisioned fate of the Earth as the greenhouse effect led to Global Warming...

And I thought, "Hmmm. I can solve Global Warming and my own problems at the same time. A ton or so of finely powdered aluminum released into medium orbit around the Earth would produce a significant decrease in Earth's insolation. Less light, less heat, and a beautiful silvery bow in the sky at night, these are all the marks of a truly great plan. The payload could be built for less than a $100,000.00, and that's a small price to save the world from global catastrophe. Boosting the thing into orbit would be the hard part, but not harder than anything else we've ever done, a ton or two is a very reasonable payload for good sized life vehicles...."

And I mentioned this to Masdibar. Of course, we discussed it, and all. Later in the day, it began to seem like a silly waste of money, we already have the moon for lighting up the night sky, the sun's only really hot for a few hours in the day (and we really should be napping then anyway), and there's not really a Global Warming problem. If anything, the planet's too cold.

But what if? What if Global Warming was a real problem? What if we decided that we didn't want to take a nap in the middle of the day? What if we decided to save trillions of energy dollars a year by having a brighter night sky? Sure, it raises the spector of people trying to stay up for 20 hours a day, but after they all succumb to sleep deprivation induced pychosis (shouldn't joke about that, it happened to my sister one time) they'll probably calm down and be sensible.

Could my dream of blotting out the sun recieve the glory and admiration that I think it deserves? Might I be the hero that saves the Earth? Can even the idiocy of Al Gore be put to good use?

The Star Trek writers guide (TOS) used to have something rather good in it. It pointed out that people today don't say, as they start a car, 'Ha! I have turned the key, causing the starter motor to rotate the camshaft and an ignition spark to enter the cylinder chamber. Now I will depress the accelerator causing the carboretter to change the air intake mix.' No, they just do it.

A writer needs to have an inkling of the way something works, to be consistent. There's no point in saying 'This machine dissolves matter into it's component elements.' and then removing steel from the resulting pile.

My favourite answer to this was from one of ST's designers. When asked 'How does the warp drive work?' He responded 'Very well, thank you!'.

Science Fiction fans are, by and large, pedants. Worse, they are knowledgeable pedants. It's probably best not to go into too much detail - you risk getting badly caught out.

Regards

Know everything, and say as little as you can get away with. Because knowing nothing and blabbing about it bites hard.