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Space Elevator An Impossible Dream?
bj8rn writes "Three months ago, the dreams of a space elevator finally seemed to be coming true after a successful test. An article in Nature, however, suggests that there's reason to be pessimistic. Ever since carbon nanotubes were discovered, many have been hoping that this discovery would turn the dream into reality. Pugno, however, argues that inevitable defects in the nanotubes mean that such a cable simply wouldn't be strong enough. Even if flawless nanotubes could be made for the space elevator, damage from micrometeorites and even erosion by oxygen atoms would render them weak. It would seem that sci-fi will never be anything other than what it is: a fiction."
What about using a thin layer of something (paint? plastic?) to protect against oxidation? Or would that add too much weight?
It would seem that sci-fi will never be anything other than what it is: a fiction.
Never? That's a very, very long time. I would never bet against never. Never always wins. (Especially if you believe in an infinite universe.)
Warp Drives do not yet exist!!!
Right after they're done perfecting the flying car.
The simple truth is that interstellar distances will not fit into the human imagination
- Douglas Adams
The technology is very young. Give it enough time and it MAY come to fruition. But in the end, it does seem very scifi.
Just have 2 stations. One on earth, one in orbit. In between the two would be nothing but space.
Have the station on earth "launch" the "elevator" and the station in space "catch" it.
Do I need to give any examples? Telescopes, electricity and magnetism, etc etc...
This tagline was transcoded to result in at least one smirk. If you experience failure to smirk, please consult your Gen
And people seem to forget that carbon nanotubes were fiction less than two decades ago.
Now, if you said "not within a decade", that I might believe.
But in my world (biochem, nanotech, biotech, pharmacom, medical genetics, proteomics) we totally change the world every five to ten years, finding our former understanding isn't a fraction of the actual reality, so I wouldn't be that pessimistic.
I'd be far more concerned with the terrorist threat potential to space elevators than to the component aspect.
-- Tigger warning: This post may contain tiggers! --
Paris in the year 2000 will be covered by two meter high horse crap.
Futurology is very risky business. Prophecies about the state of possible future technologies based on contemporary knowledge are usually not much worth, in best cases, and utmost crap in the worst ones.
If you refuse to edit incoherent rambling submissions, at least have the decency to refrain from posting them.
Reason #0 to be pessimistic: A "successful test" isn't a climbing robot. The climbing robot isn't the hard part of the problem. The hard part of the problem is the materials science.
Nor is it the sort of discoveries we've seen in the materials side of the equation; fibers measured in millimeters. That's not a prototype, it's just basic research. Interesting basic research, worthy basic research, and good basic research to be sure, but it's not a demonstration of practicality by any stretch of the imagination.
When someone builds a small footbridge out of these things, I'll be interested. When you can scale that to a mile-long suspension bridge that supports two lanes of traffic in each direction, I'll be optimistic.
We consider ourselves masters of our universe, however there is so much yet to learn.
It always amazes me how a spider can weave a thread which is so strong and flexible yet for all our mastery of the earth we cannot yet reproduce its properties.
I believe we will find a pathway to the stars, whether it is a single tether or an entire webbed tower I don't know but I am not ready to give up on mans' inginuity.
liqbase
Meteorites? Space junk? Other large flying objects? It would seem that a force field technology would be necessary in order for a space elevator to be viable without being knocked out of orbit or broken after a few months. That and the micro/macro defects in the tubes. What if the base detaches from the ground? Such a device's acceleration toward earth would be very difficult to stop with ordinary thruster motors.
Do not downmod posts "overrated" simply because you disagree with them.
I would agree with the poster, if he/she had ended that statement with ".. in the foreseeable future", but he/she didn't, and I think he/she will most likely be proven wrong. The Article however, I cannot disagree with. The article states "Carbon nano tubes cables wont hold up", which may or may not be accurate, but it doesn't make sweeping statements about the future like the poster does.
:)
Why is it that you preclude the possibility of finding substances stronger than nanotubes? Even if the laws of phsyics would state "you cant get stronger than a nanotube", I would still be sceptical. What we call the laws of physics, aren't really laws.. they are formulations and theories based on observation and experimentation, that have withstood rigorous testing and are generally accepted.
However, as our understanding of the universe grows, those laws might change too
- Tempestdata
I thought the whole point was to be constantly rebuilding the 'string' (ie running repair bots up and down the structure or finding other repairing methods). This doesn't prove that space elevators are impossible. It just means we'd need to make a few more tech advances.
Which is, of course, always the case. But the starry-eyed folk have always known they'd have to engineer some constant repairing mechanism. I just don't see how this is a big deal.
OK, the summary is ridiculous here. It assumes that because one method of making a space elevator might be impossible, that it can't be done, ever in any way.
There is so much that we don't know about the physical universe, that to even say we are beginning to understand what is possible is silly. Faster than light travel? Possible or not? As far as we have observed, not. Does that mean it's impossible? NO! We aren't even sure what time/space is, how can we say what is and isn't impossible? Is a space elevator impossible, just because this one method might be impractical? NO!
Somehow I wonder if the submitter was just trying to sound sensationalistic to make sure his story got accepted. And I just fell in his trap. Oh well. He did seem rather gleeful about the whole thing, though.
Qxe4
Humans can't fly
Humans can't survive going more than 100 MPH
Can't transplant a heart
Maybe just a simple plastic coating will protect it. Saying something can't be done should mean nothing to most people.
..........FULL STOP.
I wouldn't rush to conclude that the space elevator will never be realized. If it does take longer than initially anticipated, so be it. I would encourage LiftPort to continue its work; at the rate the space program moves (in fits and starts), perhaps a space elevator might eventually be a more economical way to lift material out of Earth's gravity well anyhow. I wouldn't want people fifty years in the future to look back and think, "Gee. The Shuttle has been scrapped. The CEV program didn't work out. IF only we had continued working on the Space Elevator, we would have an operating elevator at this time (rather than nothing at all)."
Regards, Robert Miller http://www.rocketscientists.ca/
Sorry for being slightly off topic, but as a non physicist, I've always wondered why the other seemingly obvious problems with such a device are never really considered problems. I am thinking of storm type winds blowing it off balance or making it resonate, the danger to aeroplanes, the disastrous consequences of breakage, etc. Why aren't these problems?
Even if it were possible to operate such a large collection of vacuum tubes with the small power supplies available for household electrical equipment, the glass fabrication process has too many flaws to enable mass production on such a scale. It would seem that the "personal computer" will never be anything other than what it is: a fiction.
I have discovered a truly remarkable
"Three hundred years ago, the dreams of a flying machine finally seemed to be coming true after a successful test. An article in Nature, however, suggests that there's reason to be pessimistic. Ever since Bernoulli's principle was discovered, many have been hoping that this discovery would turn the dream into reality. Pugno, however, argues that inevitable lack of pure steel means that such a machine simply wouldn't be strong enough. Even if flawless steel could be made for the flying machine, damage from wind and even erosion by sand would render it's wings weak. It would seem that sci-fi will never be anything other than what it is: a fiction."
if(!toilet_paper) roll.replace(new roll);
Certainly, sections will give way over time if left alone. I thought the very idea of starting a space elevator was first to get a small number of strands, from which more could be threaded up, using existing threads, until you had an appropriate ribbon.
Can the ribbon be built in a way that the failure of a set of threads doesn't automatically bring greater burden onto nearby threads, but instead allows for the failure to be detected and compensated for, perhaps with a second ribbon or else have the payload parachute back downward with minimal guidance by the ribbon?
Just the random guesses of a layman.
"As usual, with groundbreaking theories and inventions, we will deny it's possibility even after (if) we see it's work.
Do I need to give any examples?"
No, we all remember what it was like before color was invented. Imagine Judy Garland's chagrin in realizing she spent 6 months skipping along a red brick road. Of course, with the wonders of technicolor, they were able to disguise that fatal flaw.
And don't even get me started reminiscing about the time before gravity was invented.
What puzzles me is why there hasn't been a bigger push for creation of a Lunar Space Elevator. A lunar space elevator could be built with existing materials--though the launch costs would be significant. We'd learn a lot from this kind of practical project--and raw getting materials into orbit for a variety of purposes would get much less expensive.
Francis Bacon - Materialist-philosopher
What I think is interesting in this forum is the general upbeat attitude - that's what will make this even a possibility at some indeterminate time in the future. The basic assumption is that "sure, we can't do it now, but maybe someday. And what about *this* as an idea". Until that optimism dies, there is always a chance we'll find a way.
Materials science is *not* fully known, or even nearly so. One of the most simple compounds on this planet (H2O) has all sorts of weird and wonderful properties - new discoveries about it made the cover of "New Scientist" in the UK a few months ago. This is *water* we're talking about! It's not even organic chemistry! Who knows what a molybdenum/aluminium/carbon alloy made at *this* pressure and temperature might do...
I say let the dreamers dream, let the scientists work, and the science-fiction writers come up with challenges for the scientists. To say "never" is hubris of the highest order...
Simon
Physicists get Hadrons!
No. Really.
For the homework of one of my astrophysics classes, we calcuated that you could, if the cable was not the same thickness along it's entire length.
For steel cable, it had to be 162 (IIRC) times thicker at the point of highest tension than at the bottom. Minimum(no load).
Or something like that.
--
"I have also mastered pomposity, even if I do say so myself." -Kryten
so you make the elevator with self-healing nanotubes - a long machine really. big deal, so this just takes longer.
Why this obsession with a full blown "Space Elevator" when there is so much that can be done in the interim with tethers? Rotavators would require significantly less demanding materials and only require getting above atmosphere like SpaceShip One did recently. Then clamp on and ride the rest of the way to full orbital velocity (the tip would appear to hover briefly in sync with the Earth's rotation just above the atmosphere).
Letter To Iran
Folks, it's worth noting that tests to date have only been on the robot climbing systems themselves, using two inch wide composite fibreglass ribbons and not carbon nanotube ribbons. eg:
I expect that they'll eventually hit the 62GPa strength requirements for the metre-wide nanotube ribbons, but I'm not expecting that within the three years that Edwards is predicting.
Every time I see the idea brought up that X technology is either right around the corner, or will never happen, I take a step back and remember just how bad we humans are at seeing the future.
Remember when 2000 was going to be the year we had flying cars, moon bases and nuclear power in our homes? And how would someone making those same wild predictions have reacted to the idea of home computers? We vastly overestimated what we could do in one area, and underestimated the other. Whether this was predestined due to feasability, or whether it was a question of where we spent our research dollars, is a something I've always wondered...
Anyway, the way I've always looked at it, a new technology has several stages it must pass before we can make any assumptions about it. Each stage we get past (or get stuck at) gives us a better picture of what the future holds:
1. Does the proposed idea work within the laws of physics as we currently understand them? This is the level that perpetual motion will forever be stuck at (pardon the pun). This is also where any dreams of FTL travel and generated gravity go - they shall remain fictional unless physics opens up the possibility in in future. We can make no predictions here, other than sometimes saying "that will never work".
2. Does the technological advance require other advances first? Anything that requires fusion power, or any sort of "unobtainium" type materials, or advanced biotech, goes here. This is where the space elevator is currently stuck (another pun... ), since we can't yet produce the materials we need. Generally, anything in this category is possible, but may or may not transpire in the future - there's no way to predict either way.
3. Do we have the engineering know-how to make this work? This is often just a matter of time. Fusion power, reusable lauch vehicals and ion engines go here. I'd call this the "beta", since it's generally the stage where we are building prototypes and getting there in small steps, often with setbacks. It takes time and testing to advance out of this stage, just like in a software beta.
4. What are the practical, political, ethical, and other issues with this technology? See the hydrogen economy as an example of practical problems (ie, where do we get the energy we'd need) and human cloning as an example of an ethical problem (do we really want to do this with a human being?) Both are naturally political issues as well.
How well predictions work depends on where we are. We cannot predict the first category (except when something truely is impossible), we can rarely predict the second, we can sometimes project trends accurately enough in the third, and for the fourth one the question is often if we will, not when we can. Given where the space elevator is at the moment - a workable idea hinged on large quantities of unobtainium - I'd say we can neither predict when nor if it will happen.
Erotic is when you use a feather. Exotic is when you use the whole chicken.
This has already been addressed by Liftport, the company actually doing the work here:
I've discussed the article with a couple of CNT researchers, and they say that they're not convinced by the paper. My attitude is that we have to wait and see what really happens, because there's a lot about carbon nanotubes that we don't know yet.
Despite anyone's predictions, we won't know what the material will be like until it's made. There's a LOT of other work that needs to be done on SE development regardless of what the material winds up being. And in the "worst" case, you can still build a space elevator on the moon with near-term materials.
One thing to remember is that, even if bulk CNT were limited to 30 GPa, we could still build the space elevator. It would just become limited by finances. That's because, with a density of 1300kg/m^3 and a strength of 30GPa, the mass of a seed ribbon (using the same assumptions as in my November article - safety factor of 2, and 1,000kg capacity) would be roughly 3,440 tonnes (i.e., 3.44*10^6 kg), or roughly 170 rocket launches (using current medium-lift rockets) to loft it (i.e., ~80 times as massive as in the 2002 NIAC report). The expense and logistics of creating a seed ribbon at that point (assuming you're launching from Earth) becomes much more daunting, but not impossible.
and for people raising other concerns, which I see in several places here:
Breaking is a minor issue. Most of it would fall up. The base station doesn't support the elevator, it holds it down. The Earth's rotation keeps it up. People tend to forget the scale we're dealing with here. The bits that fall down would burn up, land as ash.
Space debris is well mapped. We can avoid it, for the most part. Small adjustments made from either end of the elevator can be used to shift the bulk of the thing. Remember, serious plans for it call for building it on a floating platform, which can move, and rockets can be used to adjust the space end of things.
Storms, well, like I said, we can move the thing. Also bear in mind that storms only affect the part of it in the lower atmosphere. Resonance is an issue which is being seriously considered, as well as induced current.
Any more problems you'd like to raise? Read the wikipedia article.
For Earth, perhaps. But for Mars and Luna, space elevators could still be built. In fact, a Lunar elevator could be built out of Kevlar, without the need for carbon nanotubes.
Bridges made out of metal? Preposterous!! Why, metal rusts when exposed to air and water. And what do you think rain is??? Won't work, I tell you! Impossible!
The current "visionaries" planning a space elevator are no different than the early flying machine designs of the enlightenment.
Da Vinci dreamed of flying. Tesla dreamed of flying without wings. All kinds of scientists dream of the future.
That doesn't meant that when the dreams come to fruition they have anything but a passing resembalance to past visions. A space elevator will probably not be constructed of carbon nanotubes, at least not of the variety we are currently playing with. Nor will it be "staffed" by climbing robots, at least not of the variety we can currently build.
I don't know anything about materials science, but I wouldn't be surprised to see us develop something that could be artifically strengthed via electromagnetism, or something else. Gotta keep it juiced up or something.
I believe the best way to characterize the article is, "Carbon nanotubes are most likely not sufficent for space elevator construction," rather than, "Space Elevator an Impossible Dream?"
The Space Elevator was an Impossible Dream before carbon nanotubes, too. That doesn't mean we give up looking for a suitable tether material, nor do we give up looking for elegant paths around the limitations in tether strength.
WhiteWolf666 an exBush supporter. All you new-school,compassionate,save the children Republicans can rot in hell
At last people might start realizing what a money dump this whole project is.
The defect problem is just one of many problems in manufacturing the CNT ribbon (eg it could take millions of years to grow a continuous ribbon, weaving them together is just not strong enough).
Common sense would dictate that we stop spending so much money on this project immediately. Carbon Nanotubes have many other applications on the cutting edge of technology, notably in nanoelectronics and sensors, that are much closer to fruition. Just as in the semiconductor industry, once these technologies mature we should see vast improvements in the growth process. Then we could turn to the space elevator problem, presumably with some defect-free growth process already in hand.
As it is we're just pouring money into a money pit of a dream impossible with today's technology. Typical of our government... missle defense anyone?
Oh well, lets just give up then. That's what inventors and scientists have always done, and thats how we got the technology-rich culture we have today.
Technoli
That's just lazy, take the stairs. ;)
Sci-fi will always be fiction eh?
Spaceflight, cloning, teleportation... all sci-fi.. none of that stuff has ever happened in reality.
There is nothing wrong with being pessemistic and pointing out flaws in a concept. In fact it is quite important.
But to say something will never work is silly.
It's basicly elevator - but more like real one. That sounds less fictious than super strong wire. And honestly something humanity - if wanted - can do even now.
All hope abandon ye who enter here.
Sheesh, what's wrong with these people?
If the current cable isn't strong enough, there are lots of possible solutions.
For example, the strength of the cable necessary is directly related to the mass of the earth.
One good sized metor at high enough velocity striking the earth, and we could build the elevator out of nylon rope.
Some other methods of reducing the mass of the earth are available here http://qntm.org/destroy
-- Should you believe authority without question?
How silly for people to think that Verne might not be smoking when he speculated that we'd land on the moon! What folly! And Clarke to think that there was a band of space where a MAN made object could stay directly above a location on earth. What a joke! And that the Earth isn't the center of the universe! And how about those fools who disagreed with the US patent office in the late 19th century when they tried to ban new patents because everything that would be invented had been! Of course we know everything. We are little gods, right? Burn anyone, everyone and anything that doesn't agree with our current understanding of the universe. Burn them I tell you!
The "Successful Experiment" was hype in so far as getting a Space Elevator built. It doesn't prove much, and it wasn't intended to. It was largely a PR exercise.
The FUD is basically saying "we don't know how to do it now, so it can't be done".
Both are silly, but the hype at least serves some legitimate purpose.
I think we've pushed this "anyone can grow up to be president" thing too far.
Is the space elevator an impossible dream? Well, duh! You are more likely to be able to beam up.
How ya like dat?
Since buckytubes can contain other atoms, if they are worried about erosion by oxygen atoms, couldn't they put some concentration of fluorine (or some other element) inside the tubes to keep electrons preferentially bound? I'm not sure about ozone, but O2 isn't going to grab an electron from a fluorine atom.
-- Thou hast strayed far from the path of the Avatar.
...just need to create self healing nano structures. Just like our bones repair themselves and adjust to impact.
:)
Seen the self replicating bots, the self reconstructing chair, I see nothing impossible in the elevator, just a few techical issues to solve.
You want to travel to the stars? Do it right: build an Orion and just be done with it. A single, or even a dozen, Orion launches would push us out further to the outer reaches of the solar system faster and more completely than the way we're currently heading: little squirts of machinery and technology at carefully planned moments. Bah!
what would happen if a commercial airliner, or flock of seagulls, were to run into the cables, or even worse, the actual elevator? would the plane split into five pieces or would the cables snap and bring the satellite down on dallas? animal rights activists would have a fit.
Current "nanotech" is mostly just fancy materials science and top-down bulk-tech chemistry (with the nano buzzword thrown in to make getting funding easier). Bottom-up active nanotech & molecular manufacturing will make space elevators, and ever more "impossible" inventions, possible.
Power to the Peaceful
When we better understand genetics and what it takes to build self-sustaining repair subsystems, we will be able to build sustainable structures that exist in our atmosphere and beyond it. It's the same with our space stations and our space vehicles. They have an expiration date that is inevitable based on chance encounter with destructive environmental agents. The Earth is a self repairing structure that has been alive for billions of years. The Moon has been up there quite a while, too, and it's connected to the Earth by gravity. If we find a way to ride that link, we may well have the elevator we need already there.
But as far as coping with environmental damage, we have the same issues on earth with just about every object we create. It wears out and it wears out pretty rapidly. Even we wear out, though our repair systems allow us to do quite a few amazing things over a long period of time before we die. If we really want renewable structures, then they will have to have a "nervous system" of sorts that perceives structural damage and a "repair system" of sorts that can restore damaged areas to original state.
This is not impossible. Our bodies are proof that it is possible. We just don't know how to do it yet. Likely because it's never been a big enough priority. When we start to use up all the easily accessible non-renewable material resources on the planet, we may start making breakthroughs in this area of recycling and repairing rather than discarding (a la "cars no longer go to the junkyard because it's too costly to waste all those materials, so instead we build cars that can repair themselves and last 3 times longer (at which point we'll probably call them "horses").
Never isn't quite now, but it's not far.
Patch the bad bits of nanotubes with duct tape. It's made from the fabric of space and time itself.
Task Mangler
Are they seriously suggesting there is no way to make a space elevator or just not this way? I would think you get work out most of these kinds of issues by engineering better materials and by using something more redundant. If one cable isn't strong enough in the face of defects could they use say four that would each support the corner of an elevator? Could they make cables that would diagnose their own injuries and repair themselves? Every weakness is something that can be addressed and fixed.
At what price learning? At what cost wisdom? The price is a man's peace of mind, and the cost is his life.
The proposals I've seen using nanotubes have had a tapered cable or ribbon. I certainly couldn't disprove it, but I'd be surprised to find that steel would actually work.
The enemies of Democracy are
If they're worried about corrosion, what about a nice dose of lightning?
n ing/faq.html
From this page:
http://www.ucar.edu/communications/infopack/light
This extract:
Just before it reaches ground, the step leader induces a huge electric potential (some 10 million volts), enough to bring up surges of positive charge from sharp objects or irregularities near the ground. Once the impulses meet--a few tens of meters above earth--the connection is established and the return stroke zips upward at a rate much faster than the stepped leader's descent. It is this return stroke that produces the visible flash as it heats surrounding air to 30,000 degrees C (54,000 degrees F), which in turn creates the shock wave we hear as thunder.
I claim using a space elevator as a power generator, assuming it lasts long enough to plug in an extension cord...
Bavarian Purity Law of Rice Krispie Squares: Rice Krispies, Marshmallows, Butter, Vanilla.
Get a lot of nanotubes in place, FAST, and then go back at leisure and put even more in place. Then go back and add some more.
In fact, why not have a tube-laying robot in place permanently, constantly laying out new 'tube, and another one that strips out the old (possibly micro-meteoritized) tubes after a sufficient number of new ones have been installed?
It is not about damage from ozone or micrometeorites, etc. It is about the frequency of atomic defects at the molecular level in carbon nanotubes.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
You're absolutely right. We don't need to shoot the moon (if you'll pardon the pun) to get a huge improvement on our current space launch systems. If the full-blown space elevator becomes possible later, great. But we don't have to bet our entire spacefaring future on something that is still basic research away from becoming a possibility.
Any sufficiently advanced technology is indistinguishable from a rigged demo
--Andy Finkel (J. Klass?)
The space elevator is a neat idea, but I think there are better alternatives. What about a long mag-lev track?
Hear me out. I think in the right location, we could build a several mile long magnetic-levitation track with the last mile slowly ascending. Given the right amount of propulsion, I think this a feasible idea. In other words think Six Flags Magic Mountain's Superman ride...
I know this would require a huge amount of money just to build, and a huge amount of power would be consumed, but I don't think it would cost more than the Space Elevator.
P.S. Why I haven't we built a space station that generates gravity with centrifugal force?
1) Carbon nanotubes have been around for at least 14 years.
2) They were never suited for this application.
3) Spider silk on the other hand...
I find that surprizing, but the problem would be the enormous weight of the thing - it would be impossible to deploy a steel cable, since it would be impractically heavy.
Oh well, what the hell...
You must read different sci-fi than I do. I feel that sci-fi's purpose is to explore what might happen in the future, to include the problems. The only sci-fi story I've read about the skytower is Ben Bova's Mercury, and the author makes it plain early in the book (hence I think no "spoiler warning" is required here for me to remark on it) that his view of the skytower is ... uh ... not 100% rosy.
Stories, whether written in litereature or in TV or movies, are the implementation mechanism by which society plays out an idea in its head before doing something to see whether it likes where it goes. For the collective consciousness to work properly, and for society to move forward in an informed way, it has to be free to explore both the positive and negatives.
Doing great, noble, historical things is not accomplished by a blind rush toward the first thing that the Guiness book of records says has never been tried, but rather by stretching for things that are, with due thought, within our technical grasp ... and socially proper. Nuclear weapons, for example, was arguably rushed through the approval process without due consideration for the social implications. Some might argue, and have argued, that a skytower might fall (so to speak) in the same category. SciFi is one of the most effective vehicles ever invented for exploring such questions.
Kent M Pitman
Philosopher, Technologist, Writer
But what if you sent it up in some kind of space elevator?
:^)
Oh, wait...
(Maybe if we built a giant badger...
Indeed, you are quite right that nanotubes have countless possible applications. These might (will) include highly efficient power transmission lines, more resilient and greatly strengthened materials, molecule-thin conductive sheets, neural interfaces, breaking moore's law by many magnitudes in processor development, and so on, but these possibilities are hardly exclusive. Such applications will immensely valuable in the future, and the various industries represented by that list are very much attuned to new developments. For example, a power transmission publication featured CNTs as its cover story just recently. ..As soon as big industry takes notice and demand increases, so will the quantity and quality of nanotube manufacture, and price will drop like a stone.
The tech is barely past a decade since its inception, so as you might imagine it is still in its infancy. Yet, there are actually quite a few groups working on manufacturing and marketing CNTs right at this very moment. In fact, the organization behind most of the recent space elevator press is Liftport. While looking to the skies, they are no starry-eyed optomists, and they recognize the great deal of work required to get to the level of materials technology capable of supporting the elevator.
As such, they are doing the R&D and capitalizing on the results. See this page for the beginning of what will soon be a booming industry.
I wouldn't worry about the small things like Oxygen and micrometorites and other debris. The real threat would be an electrical discharge between the Earth and the Solar system. Take all the energy going through an Aurora Borealis and let it go all at once through a lightning rod that goes from low in Earth's atmosphere to outside the ionosphere and BOOM!
7 earth-capacitor.htm for a graphic.
I was a big fan of a Space Elevator until I realized that we're a speck of dust floating around in a splasma globe with our Sun in the middle.
Check out http://www.thunderbolts.info/tpod/2004/arch/04092
IMarv
Trusting software vendors is no smarter than trus
... of the theoretical maximum strength of a material.
:)
Nearly perfect crystals (what TFA is whining about) have been known to fail catastrophically, and quickly for as long as people have associated the word 'brittle' with 'crystal'.
Now, many *amorpheous* covalent structures (eg: window glass - although it is often weak) can have both extreme strength - as strong as a perfect crystal, perfectly aligned - and extreme thoughness (robustness in the face of damage).
Extremely complicated - although not amorpheous, materials can also be as strong as their constituent carbon bonds, and can (not usually at the same time in nature though) be even more forgiving of damage. Most woods (particularly the softwoods we are surounded by) for example, will react to penetrations (like nails) by bending around the damage, and with the massive crosslinking, the column of fibres damaged is only weakened for a short distance near the damage.
This means that we only can be sure that the *largest* hole in the material will cause significant weakening as the others should not be right next to it and thus would be 'second and subsequent' links in an analagous chain, and thus of much lesser consequence. Amusingly, a hole wouldn't neccessarily even cause weakening proportionally to its fraction of the cross-sectional area of the material.
TFAuthor noticed that a single carbon tube is weakened after losing a Carbon, way weakened by two, and toast shortly after... then used his own 'secret recipe math' to 'prove' that big piles of nanotubes would be statistically likely to fail.
Without defining the *exact* nature of the cross-linking reinforcing the tubes you can make almost no statements about how forgiving the material is going to be of damage. The researchers quoted in TFA who are working with actual buckytubes, trying to actually build something, are correct to shrug off the TFA as being both theoretical, and wrong. They have more pressing problems (like getting past the 1 GPa point) than worrying about the theoretical maximal properties of layouts of tubes that they were not even *considered* using.
And, yes, it is freaking idiotic to say something technological is impossible, when the physics do not rule it out. It is merely *daft* to assume that something prohibited by current physics is impossible - but that is not the case here.
This isn't science, it's an ill-conceived editorial. Ignore this article and get back to work, my space monkey minions! Soon space will be ours!
Liberty you never use is liberty you lose.
Try this thought experiment. Assume a material that can support 2 feet of itself (wet spaghetti, perhaps). Make a two-fiber bundle 1 foot long. You now have a 1 foot cable capable of supporting the weight a 2 feet of fiber. Attach a single fiber 1 foot long to it. You now have a 2 foot cable capable of supporting the weight of 1 foot of fiber. Bundle two of these cables together. You now have a 2 foot cable capable of supporting 2 feet of fiber. Attach a foot of fiber. You now have a 3 foot cable capable of supporting 1 foot of fiber. Bundle two of these together and attach a foot of fiber. You now have a 4 foot cable capable of supporting a foot of fiber. Repeat until you reach the sky[2].
[1] Well, perhaps not any length. Eventually self-gravitation will cause your cable to collapse into a doughball.
[2] For a real skyhook the taper need not be this extreme as this for obvious reasons.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
No, steel isn't practical on Earth for logistical reasons. It is theoretically possible, however, and even practical on smaller planets.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
I'm always posting opinions *similar* to that around here, and I tell people in the nanotube community the same thing (reference 1 in the Nature blurb is one of my papers... that's a reference, I'm not the "never" guy). The point is not that a space elevator can't be built, but that people need to focus on more than just robotics. There are serious problems with trying to use carbon nanotubes as fishing line, let alone a space elevator. I'm really glad that someone realizes that defects may be an issue.
There are a ton of really excellent people who have worked on nanotube transistors. Many of them came through IBM, and it's no coincidence that IBM is way ahead of anyone else in developing nanotube electronics. They drove the academic research in that direction by training a bunch of people and getting them the experiance necessary to get a faculty position. I want to see a space elevator, and so I'm glad to see LiftPort finally opening a CNT research lab. If groups like Liftport assume academic researchers are going to do this research for them, they're going to be disappointed. Sure, it might happen eventually, but it may take a few decades more to get started. We need an honest assessment of what the problems are so that people will start talking about it and looking for solutions.
Hmmm Hmmm Hm Hm Hm Hm Hmmm Hmmm...
Oh no! It's SPACE ELEVATOR MUSIC!
Now I'll have that damn song in my head until I reach opbit.
We are barely there with current materials technology for a SSTO fully reusable rocket while we are orders of magnitude off on the Space Elevator. Don't you think that long before the space elevator material is in hand we will have strong, light composites for building a single-stage rocket with a very high fuel mass fraction?
The Space Elevator may be more energy efficient than the SSTO rocket, but being that the cost of energy is not the hangup and being that the SSTO benefits from the same materials technology that benefits the Space Elevator but sooner, I am saying SSTO is the way to go.
Yea, they can figure out how to make carbon nano-whatzits but they have completely forgotten about a technology called rubber which is commonly used to shield things from the elements. It's like they built a car but gave up because the engine was exposed.
or else!
Hey, some cat just showed up in my living room. What gives?
barack to the future?
The more you tell people like this it can't be done, the more likely they'll go out and do it.
It would seem that sci-fi will never be anything other than what it is: a fiction.
Top ten tech items inspired by science fiction:
http://www.michaelhanscom.com/eclecticism/2004/09It seems odd to so quickly dismiss an entire technology
based upon the problems of "wear and tear".
Ok, so we need nanotubes that repair themselves,
or replace themselves (after all if we have a robot climbing
the strand, we can surely have one that drags a new strand?)
And what about redundancy? Or different geometric configurations
of nanotubes?
The only "never" here that's clear, is that this guy
has "never" solved a problem.
------ The best brain training is now totally free : )
You haven't the faintest clue how astrodynamics works.
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....
Your solution is?
Perhaps they should have just asked you for the solution before sending up a space shuttle in a blaze of O-ring glory.
Build 2 elevators. When a strand starts going weak run up another strand at the other facility. Recycle the old strand.
Recovering that old strand is gonna be tricky though.
"Pugno, however, argues that inevitable defects in the nanotubes mean that such a cable simply wouldn't be strong enough. Even if flawless nanotubes could be made for the space elevator, damage from micrometeorites and even erosion by oxygen atoms would render them weak. It would seem that sci-fi will never be anything other than what it is: a fiction."
So nature cites a study and all of the sudden we can't have the Space Elevator even after a successful test because Pugno says so. Nature also cited studies that condemmed and rehabilitated cholesterol over and over ad nauseum. The word is still out on the space elevator being a viable technology as much as it is on cholesterol's health effects (if any) and nobody is going to scrap eggs, meat and space elevators just because of a bunch of theories and lab experiments (if any).
Oh and if the submitter put in "It would seem that sci-fi will never be anything other than what it is: a fiction" then he or she should get a ride on the space elevator with nothing much more on to wear than a space suit so they can get the "big picture" for once.
I'm glad to hear people are thinking pragmatically about this, but even the link you provided is trying to drum up "popular and political support for the Space Elevator".
Business. Numbers. Money. People. Computer World.
What is this? I haven't read TFA, but this sounds like bullshit to me.
"We've concluded that it can't be done with current technology, ergo it must be impossible"
That's how I'm reading it.
Specialization is for insects. -Heinlein
... that treats today's limitations as if they extend into the future indefinitely.
So far as I can see, all the objections mean is that a space elevator cannot be built with the technologies we currently have -- and all of them seem to be of an engineering bent, as opposed to some fundamental theoretical problem. Engineering problems tend to get solved over the long haul.
And even if the problems presented do turn out to be too difficult to construct an Earth-based space elevator, the technology could still be used on the Moon, which presents a much smaller challenge. I suspect that we already have the capabilities required to construct a lunar space elevator -- all that we lack is a permanent lunar base.
Ok ok, I've got it. Make an escalator instead. I'm sure you know whats good about escalators... (Insert obligatory Mitch Hedberg quote)
I will forever be a student.
All I can say is do a modicum of research before you make such stupid statements!
Are you saying you've never heard of rockets going to the moon? Handheld devices that could be used to talk to people thousands of miles away? And many others, all products of SciFi, long before they were a reality.
"Fact is a place Fiction's already been."
Take the 90-Day Challenge! http://rwmurker.bodybyvi.com/
1. Science fiction didn't postulate the concept of a space elevator, Russian scientist Yuri Kondratyuk did in the 1920s
2. Arthur C. Clarke, expanding on the work of Kondratyuk and other scientists, used the concept in his book "Fountains of Paradise" and postulated the use of a diamond-based filament material for use in the anchoring system
3. This guy in Italy comes out of left field denouncing a technology that has not emerged from its infancy (carbon nanotubes), and claims that they will never be strong enough?!?!
Yeah, using today's technology to make them he is probably correct, but technology never stands still and no one said that the anchor system HAD to be made of carbon nanotubes. It has to be made from a material that can withstand ALL of the stresses it will encounter in operation. Today, carbon nanotubes show the greatest promise, but they certainly aren't the end-all, be-all solution for the success of a space elevator. I can't believe Nature would publish this. Pugno is clearly just after publicity and trying to attack something that he just doesn't agree with. If he's going to shoot down carbon nanotubes, the least he could do is postulate a better solution. And how can he definitely say that it won't happen in his lifetime?!?! That's pretty naive and right up there with people saying that Mac OS X based computers couldn't be used for a supercomputing cluster, before 2003 when I helped build one.
Yes, our bodies and a cable stretching into space are different things, but we can learn important design lessons from what nature has done, not just in our bodies but everywhere. Nature is also an excellent structural and materials engineer. Look at trees and spider webs.
No, we can't just read an answer for the space elevator out of our DNA, but it is very clear to me that any solution would be self-healing and self-monitoring. That may very well come in the form of pods along the inside of the ribbon that dispatch nanomachines that can diagnose and repair structural defects.
Who can say what approach will be best. A more likely approach might be that we'll have an unrelated scientific breakthrough which will provide an economical way to get to space without an elevator and then we might never bother to make one.
But with a structure of that scope, you need a system that is relatively autonomous and can detect and repair things at the scale on which it was built. You need that, and that's what our bodies do. We can learn from that.
In other words, this is completely unverified. Even if it is verified, there may be engineering approaches that can deal with the problems.
It's a bit early to describe this as impossible and certainly not based on a single theoretical analysis.
Not that it's all that exciting if it is impossible, there are other approaches that may reduce the launch costs below what would be possible with a space elevator.
Tech Public Policy stuff
For some reason, the pessimistic tone of the story seems to impose limitations by giving up a dream, rather than actually saying that the thing is possible, but perhaps now how it's currently being tested or designed.
:)
Howard Hughes had plenty of failures before creating drastically different breeds of aircraft that enabled a lot of advancements even in space travel.
Einstein and many others developed the atomic bomb enabling tons of other advancements in science, regardless of moral issues here, the practice of the theories enabled more though of better uses for this energy.
Laser beams, once just a theory often scoffed at because of "the unrealisticly huge amount of energy" or "impoossibly clean optical surfaces" which would be required to focus such a beam even if it could be created to become anything more than a light show.
We already know elevators work, we already know that rockets work, and we already know that super conducting electromagentic engines work. What would prevent one, all, or none of these technologies from actually making *any* dream into a reality where they could be used, or used to influence future design and though?
Aside from bad laws concerning copyright, patents, and censorship, nothing should prevent a dream from becoming a practical idea, and ultimately a reality.
Damn, I got on a soapbox I guess.
--SuperBug
What if you could manufacture it in space? I'm thinking, a nuclear reactor generating heat for a furnace, mine an astoroid or the moon, or whatever. Don't build it up, build it down.
Of course, I have no idea how you would bring the cable back down to earth without it burning up...
Forget thrust, drag, lift and weight. Airplanes fly because of money.
Phantom (nee Infinium) meet LiftPort
So can a space elevator be made? "With the technology available today? Never," he says.
This quote sums up the paper. All that the guy is saying is that given today's technology, we can't do it. OF COURSE WE CANT DO IT WITH TODAY'S TECHNOLOGY. If we could, we would have done it. This is why really smart people are working on this. If you use this logic, 10 years ago you could have said, "With the technology available today, we'll never have internet connections faster than 28.8 kbps."
No Sigs!
It would seem that sci-fi will never be anything other than what it is: a fiction. "Only the Sith deal in absolutes."
Melt a nicle-iron meteor and let it drip down like taffee - except that in reality it would not want to drip down, since in space things tend to form nice spherical balls and always try to stay that way...
Oh well, what the hell...
Of course, the only reason anyone would built such a bridge is as a prototype demonstration to scare up investors. The potential ROI for a space elevator is pretty spectacular, not so much for a bridge... and buckytube isn't cheap.
//Information does not want to be free; it wants to breed.
Why not just teliport people into space like startrek? Matter transporters. *They* are the future. Invest today!
Let me preface by, I'm about to completly talk out of my ass on a subject I should not ever discuss because I haven't the slightest experience or education on the matter.
Why would it suck if it erodes?
Lets assume a space elevator cable can only last one year. Launch another tethered rocket! Weeee! It would still be cheaper than current space travel.
I fully expect a response explaining why I'm an idiot, but I would like to hear the explanation.
time is a perception of a being's consciousness
time is your 6th sense, the wierd ones are 7+
It is equally arrogant to think that we aren't. That is to say, "It is arrogant to think that we have an answer to that question."
In this case you have.
If there is anything of value on the moon, worth bringing back in quantity, it would seem to be the perfect place to start with a space elevator.
No atmosphere and less gravity, along with it's relative proximity to Earth makes it a good testbed for such an endevour.
However, the costs involved necessitate that there is something on the moon worth the effort - as a strictly R&D, proof-of-concept deal, even the Moon is too far away to build it just because "it is there".
This issue is a bit more complicated than you think.
In Soviet Russia, the cat dissapears YOU!
You are quite right in saying so, and it was entirely my intention to make that point. As I said, the industry has quite some time before growing beyond its infancy. However, the main point to be made is that people are attempting to be forward thinking and, indeed, pragmatic enough to realize that the requisite infrastructure for the elevator must be established. Only then may genuine progress be made towards making what today remains science fiction into reality.
As for current realities: many promising, potentially useful applications are developed every year.
You know.. I'm sure someone was saying similar about that cable to.
One was finally laid on the third(?) attempt.
Ya Know It.
Storm
Dammit! There goes my dream of hopping on the space elevator and punching the button for every floor ...
"My God...it's full of trolls!"
forget horseless carriages because they need work done on them every few thousand miles
:)
forget steel bridges, because they need maintenance every few months
forget voice recognition, because it's too complicated
i remember reading a story (sci-fi) which was talking about creating shields and using them for spaceships. in it, the best mathematicians on earth worked out that a longest-lasting shield would have a lifespan of 1 second, since it takes eponentially higher amounts of energy to maintain with time - and thus that no shield would ever be useful. meanwhile, some engineer thought of flickering the shield on and off like a flourescent light - and built a spaceship with a shield.
moral of this story - never underestimate ingenuity. (yes, stupidity too
Did you know that "FTW" ("for the win") is a direct translation of "Sieg Heil"?
Civil engineers simply build things stronger than they need to be. The safety margin allows a structure to absorb some damage from rust, rot, barges running into it and so on while remaining robust enough not to kill anyone.
Set up an elevator, and when micrometeorite damage reduces the safety margin too much, use it to haul up its replacement.
NT
I remember that I told you it seemed too strange for me that such group of higly educated individuals like the Slashdot posters, were taking this Space Elevator stuff so seriously...the flames received were inbelievable, even my post received a rating of 1 (ONE) while some sci-fi postings received 5 as 'Insightful' or 'Informative'..... It was like we'd talk about intergalactic travels as something something just around the corner, why were so pissed off by my skpeticism back then?
All we need is a material that is very much lighter than the vaccum. Then you attach boyancy pods along the entire cable and it will just float there...
000
001
011
010
110
111
101
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any infinity that is smaller, greater, or anything but equal to any other infinity is not true infinity.
Can't wait to fart in one of those things!
Social problems are fairly unsolvable. They would require political will, together with political competence, and if we compare the job-relevant skills/motivation of an average technician with an average politician, we get results saying loud and clear that technical problems, even of this magnitude, have far better chance to success. Even if we include MCSEs into the technicians set.
So feel free to deride, but remember your words two decades from now and then refuse to use nanotube filament materials and other goodies born from the undeserving dream of Kalidasa's Tower.
ZOMG!!11oneone!! one cable might wear out or wont be strong enough...
well use 3 for redundancy, make them segmented, assess these segments and replace them as needed.
this is like saying "break pads have a tendency to sheer away and wear out, we must find something else to stop cars"..
granted it's on a much larger scale, but we are still talking the same thing here.
VLC FOR MAC IS DYING! IF YOU DEVELOP, PLEASE SAVE IT!!
It was impossible for comets to glow by themselves, let alone in ultraviolet, but they do.
It was impossible for a 25cm remnant to remain from the object forming a 43km wide impact crater on Earth, but it did.
It was impossible for a flat channel 3000km long to form, but Valles Marineris exists on Mars, 10km deep and 90km wide and more. Carved by what? Hardly water, since roughly half of the carving was done uphill.
These are a few of the many impossible things which exist apparently for our collective puzzlement. Many.
Mr. Pugno seems to miss the fact that nobody has started up the spinerettes yet. Nanotube technology has only been around for about 10 years now and we still haven't gotten to the point of nanoassembled tubes, we're still using large scale deposition methods. The use of the term "never" in Pugno's analysis seems to imply a personal bias. Good scientific-method thinking doesn't, as far as I was trained, include the concept of never when you're talking about evolutions of existing technology. We might "never" have warp drive but it's only a matter of time until nanotubes, an existing technology, are spun up in practical sizes at strengths reaching 80%-90% of the theoretical maximum. Pugno seems to be spewing FUD which makes you wonder about his motivation.
"Secrecy is the Beginning of Tyranny" "No intelligent man has any respect for an unjust law" -Robert Heinlein
So, we've found a few flaws in our plan. I doubt that means that this will be scrapped forever. We're always developing new materials and new ways to apply them. Perhaps someone will come up with a nanotube which has a non-reactive sheathing that can resist oxygen erosion.
There are also other avenues to space. We haven't heard much about laser powered propulsion, but there are possibilities as civilian and military researchers develop new and more powerful lasers. It would be a nice swords-into-plowshares project if we could use some of the military's new weapons for an application like this.
Also, we don't necessarily need to be able to loft huge payloads at first. If we can send up small satellites or maybe even a small manned capsule repeatably and cheaply, it would be a good start. That is after all how we started with chemical rockets, so there's nothing wrong with starting small.
It's good to use your head, but not as a battering ram.
There is plenty we don't know and many breakthroughs left in the universe, but I think it's human arrogance to think we're capable of omnipotence.
You are thinking too small. We simply cannot grasp infinity with our small minds. (Much less a billion years) However, the universe (or at least our present universe) is not infinite in time either so I put this to you.
If we do not achieve "technological omnipotence" then we will simply cease to be.
This might be from now to 100,000 years when a meteor hits our planet or we get hit by a gamma ray burst and wipe us out.
If we are looking at a longer time frame... Say 10 to a 100 billion years we are faced with the prospect of the Sun dying which involves it turning into a red dwarf which will expand and consume the earth. Even if we move to Mars or Pluto this will not be good enough. We must make it to other systems.
But even then it is not good enough!
We must find a way to reverse the 2nd law of thermodynamics or else we will end up with Heat Death of the Universe in 10^1000000000 so billion years.
Of course some postulate will face a Big Crunch of the universe where everything falls into a single point. I don't think without some type of superior technology will we be able to survive such an incident either.
Yes... Most of us will not be around by then, but the universe has a suspect time limit (if may not of course), but if we (human race, machines, aliens, or whatever is around at that time) haven't achieved true control of the universe via technology we will simply cease to be.
So our choices are either we achieve this state of Technological Singularity or we accept that the human race is going to be dead and the universe will go on without us.
I'd rather take my chances (and a bit of hope) that we will be able to overcome our current technological limitations and achieve this in 100, 1000, or 100,000 years from now.
Every day we stay grounded on this planet is more one tick towards 0% survival rate of human race.
"I am the king of the Romans, and am superior to rules of grammar!"
-Sigismund, Holy Roman Emperor (1368-1437)
Interstellar travel and space elevators are anything but just around the corner. But we're geeks, and don't go telling us what we can and cannot dream! Unless you learn to duck!
... well let's put it this way: for every flying car we don't have today, we have a personal supercomputer no one thought we'd need.
In 1900 the mainstream scientific view was that we'd nailed all of the fundamentals and all we had left to do in physics was measure the details. Like a thunderbolt, Einstein struck - not to mention a veritable renaissance - and the idea looked like the despicable ignorance it was.
Predicting the future is
Whenever someone mutters "is science finished?" I yell a brick and I keep a clean conscience.
You're right, I think.
It's like saying that the Human Genome will never be decoded in less than 50 to 75 years.
That was probably true when the HuGo project started, given technologies available back then.
But because the biggest effort was done by public Universities, freely sharing result, tremendous advances were made, and with it incredible advance in sequencing technology.
In the end most of the work was done in 15 years, the last tiny bit being finished after 20 years.
According TFA, the main problem is that there's a gap between the theoretic maximal strains that can be sustained by a "perfect" strand of nanotube (~ 50% more than needed) and the strains that can be sustained by a ribbon produced with technology we could have in a near future ( 1/10th of what is needed).
Thus the discrepencies between the NASA experts (nanotube can make elevator possible) and TFA's autor (we cannot make perfect enough nanotube-based ribbons for a space elevator)
I think if the space elevator research is done by networks of openly colaborating universities "à la HuGo project", maybe advance in nanotube technology will be made faster. More money will be brought by investors in related industries (like how faster and newer sequencer were made during HuGo), and maybe will be able to develop "good enough for elevator" technologies in the near future, sooner than the pessimistic article.
"Sufficiently advanced satire is indistinguishable from reality." - [Tips: 1DrYakQDKCQ6y52z6QbnkxHXAocMZJE61o ]
With the newly reported developments in invisible cloaking, how do you know the cable isn't already deployed?
-- Gary Goldberg KA3ZYW 301/249-6501 AIM:OgGreeb Digital Marketing Inc., Bowie, MD
Does a giant elevator register omnipotence to you?
M /DRDOOM.htm
I think it would be arrogant to assume we won't ever be capable of this one thing. I hope we've grown out of the idea by the time it's possible, though. Seems a bit of a waste. Give it 5 years and it'll be converted into a giant version of Dr. Doom's Death Drop:
http://www.universal-excitement.com/ISLANDS/DRDOO
You're inaccurate at best in several places. Please tell me this is just stuff you picked up by reading the internet, and not the result of a formal mathematics education.
...} than there are positive even numbers {2, 4, 6, ...}. Consider the mapping from the evens to the naturals of f(x) = x. So 2 maps to 2, 4 to 4 and so on. Now, the natural numbers 1, 3, 5 and so on don't have corresponding evens. You would, at this point, say that there are more positive even numbers than natural numbers; the argument is the same as the one you made.
:)
It's called Cantor sets, there are more rational numbers than there are whole numbers.
First, the Cantor set is a fractal. You're thinking of Cantor's diagonal argument.
Also, there aren't more rational numbers than there are whole numbers; both are countably infinite. A bijection (one-to-one and onto mapping) can be established by considering rationals as ordered pairs of natural numbers and enumerating thusly. You're thinking of real numbers, which are not countably infinite.
For a really simple example (there are more formal ones out there) take the following series: [snip] As you can see, for every single integer there is a corresponding real number. This list is one-to-one but not onto, the list on the right will never have 1.2 in it's list, therefore there *must* be more real numbers than there are integers. In fact, it turns out that there are an infinatly greater amount of real numbers than there are integers.
Okay, now you've switched from rational to real numbers. But your example still proves nothing. The fact that the function you made up fails to be a bijection doesn't prove that no such bijection exists. By analogy:
There are more natural numbers {1, 2, 3,
You would, however, be wrong; there does exist a bijection from the evens to the naturals using the functions f(x) = x/2. So 2 maps to 1, 4 to 2 and so on. Every positive even number maps to one natural number, and vice versa.
To prove that two infinite sets do not have the same cardinality (that is, the same number of elements, though the concept is extended to include infinities), you can't just make up a bad mapping; you have to prove that no such mapping can possibly exist, like Cantor did.
Don't go to far with this though, I understand that Gregory Cantor went insane trying to find the next greater space
Not exactly; the unsolved problem that Cantor never found the solution to was the continuum hypothesis; he asked if there was a space with cardinality between that of the natural numbers (countably infinite) and that of the real numbers (the continuum). It turns out that there answer is independent of standard set theory; it works with it true, and it works with it false. But this is a pretty abstract question, and not as earth-shattering as the initial discovery that there are more reals than there are rational numbers.
Laws do not persuade just because they threaten. --Seneca
Maybe if we can find ways to increase the amount of carbon dioxide in the atmosphere, it will protect the cable from oxygen damage.
FTFA:
Edwards, who is president and founder of the Dallas-based company Carbon Designs, shrugs off the controversy, and says that with adequate funding he could make cables at or above the 62-GPa benchmark in just three years.
Well, hell, with adequate funding, I can promise you that I can capture, move, and place in earth orbit an asteroid with huge deposits of precious metals, ready for you to strip mine for sale on earth, and of course we can start in less than 3 years. Just give my council a call and he'll go over the necessary non-disclosures before we talk about how many zeros to include in that funding check.
Is it just my observation, or are there way too many stupid people in the world?
The cat who walks through walls.
duh, fud, space, no, yes tells me everything I need and more.
Nothing that big can be 100% reliable. At some point, it's going to break. And when it does, you'll have a 200-mile-long, nearly-unbreakable bandsaw blade whipping around the atmosphere and dragging along the ground.
Any cost savings for energy usage will be totally eaten up in liability-insurance premiums, or dwarfed by tort settlements, depending on whether it's before or after the inevitable happens.
I will grant you that things of this scale do not fit the paradigm of everyday items (aka "everyone owns a washing machine"). But to dismiss some of these items is just asking for trouble.
Compute the resonance frequency of a device 60,000 miles long.
Which mode would you like to excite? Things don't always fail at the first resonant frequency. Many/most do, which makes the others that much more spectacular (and unexpected, I might add).
What danger to airplanes? Are you envisioning something that's going to randomly and rapidly maraud across the surface of the Earth or something?
Of course not. Not until it snaps due to a flaw or an unforseen event. I'm not saying that there will be a plane flying around when the string goes pop (note, I said "when" not "if"). That chance is very, very remote - you know, like large-comet-impacting-Jupiter remote.
On the flip side of that argument, luckily, nobody has any reason to intentionally try and fly an airplane into such a structure. That's why planes never fly into buildi... oh, right.
For instance, what you probably think happens if there is a cut near the ground is the exact opposite of what happens, because your intuition is not set up for these kinds of problems.
So what happens when the fiber is severed in low earth orbit? There's a lot of money tied up in communications satellites, and the companies who own them would be pretty pissed off to lose them. Not to mention the public outcry if the loss of a major bird or two interupts their viewing of the World Series.
Even more interesting is what you're going to do with all the low earth orbit satellites. There are lots of them out there, and they'll be travelling at up to 7km/s relative the fiber (perpendicular to the strand axis, esp. for polar orbits). Not all of them are active (LAGEOS and similar passive reflectors come to mind), and will no be able to correct their orbits. No matter how thin the strand, eventually their paths will cross.
Your intuition is worthless. Nothing personal; mine is too. Having studied the topics involved I can say I understand some of this stuff intellectually, but I can't say I understand it in my gut. But I do know not to trust my gut in this domain.
(For what it's worth, similar concerns apply w.r.t. nanotechnology. Your intuition about how things work does not do very well at that scale. Our brains function at the in-between scale we all live and work in, and does not do well outside of that domain.)
Yes, when you deal with orbital dynamics, the x, y, and z we deal with on the ground doesn't apply anymore. In addition to the article, there is one other thing that will keep the space elevator from happening in the lifetime of my children: safety. I've mentioned it above, but this sort of thing is going to have to be safe. No, I take that back, it's going to have to have a proven failure rate of zero. Too many things can go wrong, and the publics tolerance for failure is so thin - well, it makes a carbon nanotube thickness seem large. I think the political hurdles are larger than the technological ones - and that's saying quite a lot.
Is it just my observation, or are there way too many stupid people in the world?
Yes, not only can you excite any mode but, energy dissipation is likely to be exceedingly low, meaning that oscillations can grow almost without bound even with a very small excitation. This is a significant problem but, one that has generally been off the radar screen for space elevator enthusiasts.
> Control of matter will be a no brainer. Dare I say even altering physics and our own realities.
The laws of physics control behaviour of matter and energy in the universe.
We are composed of matter and energy in the universe.
Ergo, the laws of physics control what we can even theoretically accomplish.
If the laws of physics don't happen to be in a configuration which allows them to change themselves, then tough luck for us---it will never be possible for us to change them. The laws of arithmetic can't be used to change themselves; maybe the laws of physics can't be used to change themselves either.
(That's assuming a purely-naturalistic universe, of course; assuming supernatural effects complicates matters.)
I believe what I believe and don't try to confuse me with facts!
> happens in human advancement will be short term.
Not necessarily - I can think of four scenarios offhand that would prevent that:
1) Extinction
Obvious.
2) Other permanent change
For example, if a cult released a retroviral pandemic that altered everyone's DNA to make people (and their offspring) incurious, then people wouldn't want to question or to do science. If the changes became fully-established through the entire population, only random mutation would knock us out of that rut, and that's by no means a guarantee.
3) Stable social structure
While we haven't yet come up with a society that's stable for millenia, that doesn't mean one doesn't exist, and that doesn't mean such a stable structure might not be anti-science.
4) Recurring pattern
It may be that there is a cyclic or otherwise recurring pattern in human behaviour. If we keep blasting ourselves back to the stone age every 5,000 years, there may be no accumulation of progress.
(That being said, I think it's most likely that serious science will still be done in 100, 1,000, and 10,000 years. And I'm wildly curious what it will show.)
Well, first of all that was about numbers (not ordinals), of which there is indeed an infinit number between 3 and 4. Now about those "geometries". Here's a simple example. Take a paper tape Lets say it's 1.1 some units long. Write 3 and the beginning and 4 1 unit away from 3. Now make Moebius strip, keep mooving another 1 unit and put 5. Now, where's 5 on this strip? :-)
There is a time and a place for mathematics to be deep and mysterious.
Ummm, or maybe we should not "angrily" discard the existance of some dimensions and geometries we (as "humans") know nothing about just yet?..
I disagree that If nothing else, then a bunch of attractive side effects; is a reasonable reason to pursue a goal that is epic in scope, to reap benefits that are achievable NOW. If it was funded, it would not be worth it, but people are still talking about it, why? Why not put continue research into personal flight devices which are easier to engineer and infitely more pratical? Ah, there's the truth of it! Advocates of the space elevator are communal fanboys* interested in a "new" scifi mind-game because there's not a lot of work involved in arguing future possibilities. The old scifi toys like jetpacks aren't in style anyone! Why? Most people are just plain tired of talking about 50's scifi given the demonstrated difficulties which trashed their childhood dreams. That space elevator though, VERY POSSIBLE! WHOO HOO because nobody is going to waste money on it and crush those dreams similarly for some time.
*Note:
This is not to say fanboys are bad, many fans are righteous advocates of good concepts, products, and ideals.
Often wrong but never in doubt.
I am Jack9.
Everyone knows me.
Can you provide some sort of reference for that? Everything I've heard (including an SEC-filed complaint) about the Moller flying car is that the guy (Moller) is considered a spectacular fraud, and makes his money off of investors.
I'd love to learn that some useful tech had actually come out of the program but I've been watching him for 20 years and haven't seen a hint of it - just breathless popular technology "news" articles.
"It is our blasphemy which has made us great, and will sustain us, and which the gods secretly admire in us." - Zelazny
This dream may still be possible Suggest you look at a Company called CTIC www.cleantechnano.com as they have produced 99.9999 as grown nano spheres that just might have the caracteristics far superion to SWNT to overcome your concerns You might want to attend or look into the U of C Nano Seminar July 16 th through 20 th where this breakthrough will be unveilede by Dr Sharnov
Never say never!!! I'd say they'll eventually arrive, even though we may have to overcome a few "obstacles." (Obstacles are those frightful little things you see when you take your eyes off your goals!!!)
Twenty years ago, the best guess for how the space elevator would be built involved some kind of massive cable constructed of artificial diamond molecules miles long. New discoveries have changed that perception, so now we believe that carbon nanotubes might be the material that makes the space elevator happen.
One that that is for sure, is that the quality control of nanotubes isn't yet as high as it needs to be. There are all kinds of conflicting claims from various suppliers as to the strength of the materials they produce. At the high end, nanotubes seem plenty strong even with occasional defects.
Any realistic design is going to allow for repair and maintenance, which is what is needed to counter these problems.
As far as the oxygen problem, only a very small portion of the overall cable is ever in the atmosphere. Regularly replacing that section of the cable probably won't be terribly expensive.
Micrometeorites are also a concern, but the designs I've seen take them into consideration.
The fact is, the potential profits for a space elevator are enormous, more than enough to fund the needed maintenence work and continued development of advanced materials.
-All that is gold does not glitter - Tolkien
www.ra
The study talked about one flaw in a trillion atoms. Imagine the following, steel
wires glued together with fairly weak glue, with a random gap in each wire every
60000 miles. The bulk cable is still going to be quite strong, the glue along each
wire while weaker than steel can easily move the load from wire to wire. I suspect
a carbon nanotube composite will be no different. Infrequent defects will be
irrelevant because at any given location only one of billions of tubes is effected.
Remember this one when patent prior art comes up...
Wear on the ribbon can be dealt with by slowly changing out the ribbon. Have a roller
on the outer space end that slowly takes up ribbon, and a ribbon construction facility
on the ground slowly putting out new ribbon.
This article from doing actual measurements found a highest strength of 63 GPa:
P DFs/science-9.pdf
n s/16.MSE%20A334demczyk.pdf
1 /5502/283
Strength and Breaking Mechanism of Multiwalled Carbon Nanotubes Under Tensile Load.
SCIENCE, VOL 287, p. 637-640, 28 JANUARY 2000
http://bucky-central.mech.northwestern.edu/Ruoffs
This report showed actual measured tensile strengths up to 150 GPa:
Direct mechanical measurement of the tensile strength and elastic modulus of multiwalled carbon nanotubes.
B.G. Demczyk et al.
Materials Science and Engineering A334 (2002), 174, 173-178.
http://www.glue.umd.edu/~cumings/PDF%20Publicatio
Both of these studies were done on multiwalled tubes since they are larger and it's easier to make attachments with them.
In the earlier study in Science, the authors from SEM imaging noted that it was actually the outer single-walled nanotube that broke first therefore it was carrying the load. This would make sense from the way the attachments were formed which could only form a bond with the outer surface of the multiwalled tube. Therefore the numbers quoted were for the strength of this outer single-walled nanotube using as thickness only that of this single-walled nanotube.
However, in the later study in Materials Science and Engineering, the authors believed the attachments were made to all the layers of the multi-layered nanotube, which would explain their higher measured strength.
The prevailing theory is that the range of strengths is due to the number of imperfections in the nanotubes. So we should be able to look at the nanotubes at the nanoscale using SEM,'s, STM's or AFM's and find which ones have the least imperfections. These should be the strongest tubes.
In the Science study, 1 out of 21 of them, 5%, have the best strength, 63 GPa. At a production of millions of tubes at a time this should still be feasible economically and technically.
The lengths of the nanotubes in these studies were however, were at the micron scale though. Nanotubes have been created at the centimeter length scale, but as far as I know the strength of these have not been tested.
Note that the reported strengths of centimeter long or longer "fibers" made of nanotubes being less than 1 GPA are not measuring the strength of individual nanotubes at these lengths. This is because the fibers are composed of the nanotubes stuck together end to end by weaker Van der Waals forces, rather than the much stronger carbon-carbon bonds that prevail in individual nanotubes.
Here is one study that detects, characterizes defects in the nanotubes at the nanoscale:
Resonant Electron Scattering by Defects in Single-Walled Carbon Nanotubes.
Science 12 January 2001, Vol. 291. no. 5502, pp. 283 - 285.
http://www.sciencemag.org/cgi/content/abstract/29
Methods such as this might make it possible to find the nanotubes with the least defects beforehand and therefore automatically select those of the highest strengths.
Bob Clark
Thanks for posting that - when I first saw the episode I lacked the framework to realize that Q have root on the Matrix. Now it makes much more sense.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
You most certainly can excite an upper mode from the ground. All you have to do is hit it with the right frequency. Not only that, but that is not the only place you will get excitation. You've got thermal expansion and contraction going on all the way up. You've got tidal forces. You start moving around a good bit and you'll start to get Coriolis acceleration pumping your modes. You do not want to fire thrusters to damp out oscillation. They would have to be placed all along the elevator, at least four thursters at each location (at least two locations per critical node) for 3-axis control, with all the additional weight that entails and a hazardous network for replenishing highly reactive propellants. Not only that but, damping vibrations with thrusters is extremely risky as you are quite likely to pump energy in rather than take it out. No, what would be needed would be a network of passive dampers such as they use in skyscrapers in Japan to damp out earthquakes. We are talking a lot of added weight here. You need to be a little careful criticizing others for "ignorance". You appear to live in a glass house.
As the elevator car travels up or down (assuming it makes complete journeys and is unlike a building elevator that goes from floor to floor in both directions) why not have the top of the car scrape off the old outer layer and the bottom of the
car apply a new fresh outer layer (when acending, These functions to be reversed when the car is decending) Good engineering would normally have the cable oversized anyway.
Assuming they only manage to make near-flawless nanotubes, has anyone condsidered two possible solutions to this issue?
1) Build the nanotubes around a semi-flexible nternal structural support (in other words, a loosely connected skeleton) to add to the structurals strength. It might significantly increase the weight, but that might not be that much of an issue if the tethering is balanced properly.
2) Transport units would be frequently, if not constantly, sliding up and down the tether...so why not give every transport unit a resevoir with a pump that constantly squirts a thin coating of protective gunk in a gelatinous form over the cable(s) as it goes up or down? Something that sticks to the surface of the cable and can only be beaten away by constant bombardment? If the robots are constantly spreading this stuff up and down the tether, it could conceivably solve the wear-and-tear issue.
Of course, 62,000 miles of gunk would make for a pretty hefty tank, but it's a good direction to an idea if not a good idea in and of itself. Odds are, the same elevators travelling the tether would be outfitted with sensors designed to inspect the cabling for wear and tear as well as defects that only become apparent after being put under strain.
"Courage is being afraid to do the Right Thing, and doing it anyway."
Entropy is!
There is a finite amount of energy in the universe and it is expected to expand into infinity. That tells me that at some point energy (in whatever form is exists) will eventually be so dispersed as to render meaningful intelligent action at any single point rather... well pointless.
Time may indeed be infinite, but the amount of time we have to develop a useful space elivator is somewhat finite.
I won't bet against us ever developing such a device. A more interesting question to me is whether we develop such a thing before it is necessary or needed (translate cost effective versus other options).
Oh, sign me up for the first one way trip to another planet! I don't even care if I am alive when it gets there. It would be cool to just be amongst the parent seeds of the new humanity.
Slowly waving my hand - "This is not the sig you are looking for."
"There is plenty we don't know and many breakthroughs left in the universe, but I think it's human arrogance to think we're capable of omnipotence."
True omnipotence? No. But that's because it is an infinite superlative, just like 'never'.
This is exactly the one thing that makes me feel somehow...in awe...for my own race. (morally/socially/etc. there speaks as much against it then for it). Some art or music evokes the same, but..science, and it's modern child technology, has the feeling of a tremendous...force. A force that keeps getting better and stronger while time passes. And, provided the human race continues to exist (or our maybe-less-human heirs) I *do* think that we will get pretty close to omnipotence. In principle, we are all gods. (Or will become so; - gods here more like the ancient Greek gods, not the classic god-concept of the bible and consorts).
In fact, the technolgy we have today would already be god-like to someone of 1000 years ago.
So, humanity will be capable of *almost* everything.
--- "To pee or not to pee, that is the question." ---