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Nanotubes Start to Show their Promise
Rei writes "Researchers at the University of Texas at Dallas have developed the highest quality nanotube sheets to date (the team previously set strength records with polymer-nanotube composites). Producable at a rate comparable to commercial wool spinning, the transparent cloth has exceedingly high conductivity, flexibility, has huge surface area to volume ratios, can potentially be made into very effective OLEDs and thin-film photovoltaic cells, and outperforms even our best bulk materials (such as Mylar and Kevlar) at strength normalized to weight. It strongly absorbs microwaves for localized heating (leading to applications in seamless microwave welding of sections and even windshield warming), changes conductivity little over a wide temperature range (very useful in sensors), and is expected to be used in commercial applications very soon. The research should even be expandable to artificial muscles! To head people off, while the exact tensile strength is not listed, it sounds like it is still far from the >100 GPa needed for a space elevator. Anyways, here's to process advancements!"
I'd like to see these sort of things geared up with 'smart' nanotechnology to make 'smart' cords and stuff like that, imagine a highly conductive wire that provided +, - and ground and detangled itself, or melted into a pool and you just pulled cord out of it, all detangled or bent into whatever shape you want.
I'll subscribe to Slashdot when I see a month without a dupe, a typo, or an article the "editors" didn't read.
Oh good. I wonder how much it will cost for a packet of laser printer paper made of this stuff?
I could use something snazzy for my resume.
Democrats or Republicans. They are both taking us to the same place and they are not afraid of us anymore.
And yes, folks, it cures most deceases and will get rid of that bronchitis for you and you can use it to clean your hubcaps.
To head people off, while the exact tensile strength is not listed, it sounds like it is still far from the >100 GPa needed for a space elevator.
Why do they say they're going to enter the material into some space elevator competition at the end of the article then?
http://twitter.com/onion2k
I can soon have a solar powered bulletproof jacket that enhances my strength, protects me from cell phone emissions, and displays DVDs?
Or, from the article, and perhaps of more interest to us:
"flexible computer screens that could be rolled into a sack"
Haven't we been promised this for years? I wanna roll up my computer screen & carry it into my flying car!
...the cost?
I know tfa says that it will be efficient, but does that take the cost into perspective? It's not unusual to hear about a new idea that is totally ground braking in several fields, then the research on the commercial fades out, because they find out that it's too pricey. A lot of products was that way in the beginning. Just look at LCD screens etc.
Well. That being said. This sound awesome, I'd like to see it developed...
Scully: Should we arrest David Copperfield?
Mulder: Yes we should, but not for this.
Yes, it's producable at a certain rate- but what about the cost? Is it economically feasible?
Unfortunate about the space elevator. Looks like the highest we've gone is 63 GPa (http://en.wikipedia.org/wiki/Tensile_strength)
It is the resource usage and sustailability that makes it worthwhile. Cars cost a shedload of cash, but they are still bought. People work longer and longer hours, parents both work. Why? Because they want to buy the things they want and they are expensive.
Cost is irrelevant.
If the cost of the item is too great to be commercial (as computers used to be), it will be bought by those with the need for this stuff. After a while, it will become cheaper, as computers did.
However, if the creation of these nanotube materials is not resource efficient, then they will never be able to become widely used.
Super, I envision the day where I can replace my tin-foil hat with a nanotube beret.
Height: 38U, Weight: 0 Newtons, Eyes: #0000FF, OS: Gray Matter 1.0 (Alpha)
if they ever remade the Graduate, that line would go...
Mr. McGuire: I want to say one word to you. Just one word.
Benjamin: Yes, sir.
Mr. McGuire: Are you listening?
Benjamin: Yes, I am.
Mr. McGuire: Nanotubes.
That, and once again punish Paul Simon with another reunion with Art Garfunkle
The researchers have now shown that by teasing nanotubes away from one side of a forest and attaching them to a strip of sticky tape they can draw the nanotubes into a continuous sheet. Umm, surely this must be totally over-simplifying what they -really- do..
Well, the greatest danger to the clean, sterile environment is carbon-based, you know...
Segmentation fault. Ore dumped.
and outperforms even our best bulk materials (such as Mylar and Kevlar) at strength normalized to weight. It strongly absorbs microwaves for localized heating
Should be interesting to see the day when a drug dealer overrides the safety interlock on his microwave and points it at nanotube body armour wearing DEA officials during a bust.
Should bring a new meaning to the phrase "hot tits"
Hmmmmmm..... Deep fried and look like Squirrel.
and human ;-)
Java Oracle Linux Enthusiast
It strongly absorbs microwaves for localized heating (leading to applications ... in windshield warming)
Yeah, I'm going to have a microwave generator going in my car, aiming the the windshield, just to warm it up. That's got to be safe right?
Just a shame we can't do something slightly safer, like send a small electric currents through tiny wires, or blow hot air at it.
But oh no... we have to shoot microwaves through our cars instead.
Conservation of energy is a law of physics (ok, as long as you don't include General Relativity, at least). So you don't need carbon nanotubes to conserve energy.
:-)
However maybe it helps with conservation of entropy
The Tao of math: The numbers you can count are not the real numbers.
I'm still waiting for my microwave-controlled nanotube jetpack, powered by stirling engines and hydrogen fuel cells.
http://groups.yahoo.com/group/stoptheelevator/
I'd suggest a balaclava. You get better coverage that way.
"OH SHIT, THERE'S A HORSE IN THE HOSPITAL!"
The reason why nanotube composites don't end up being nearly as strong as nanotubes is that nanotubes are very slippery inside of a composite, so once force is applied, it doesn't transfer through the interface and the ultimate tensile strength is primarily determined by the composite.
In this case, when they are weaving fibers together, the weakness in tensile strength will come from the interface between linked nanotubes which will have a tensile strength many orders of magnitude than that of an individual tube.
in the first link: "For example, Baughman and other researchers would dearly love to create artificial versions of the body's muscle fibers, which can convert a chemical energy supply into mechanical work with even more efficiency than a car engine." and what's the efficientcy of a car engine? 30%? its pretty good but the sentence seems to imply that a car engine is more efficient then say an electromotor. (ofcourse an electromotor needs its more generated elsewhere, but these nanotube also do)
if there was ever a technology that could benefit from more people working on it, this is it.
For me, nanotech is probably the most exciting thing going on at the moment, it's a shame that more people can't take a hand.
Even in GR, the stress-energy tensor has zero divergence.
Those who can make you believe absurdities can make you commit atrocities. - Voltaire
"...and is expected to be used in commercial applications very soon..."
:(
,
Hmmm, hasn't that been the case for the past decade? That's what my inner cynic says, anyway. Just like the fuel cell revolution, not to mention the nuclear fusion revolution.
there should be a revolution any day now...
on that page was the urine powered battery.... Now that could useful. Drink a few beers and power your laptop.
Finally, a pair of underpants that won't wear out!
intr.v. deceased, deceasing, deceases To die. n. The act of dying; death. And disease (d-zz) n. A pathological condition of a body part, an organ, or a system resulting from various causes, such as infection, genetic defect, or environmental stress, and characterized by an identifiable group of signs or symptoms.
Java Oracle Linux Enthusiast
If it strongly absorbs microwaves, I wonder about its potential as a radar-absorbing material for stealth military aircraft, leadfoot driver's cars, etc.
tm
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by teasing nanotubes away from one side of a forest and attaching them to a strip of sticky tape
again proof that duct tape can make anything work!
Soon we will have duct tape made out of this nanotubes, after that, who knows or even dares to dream!!!
The Dallas Morning News (19-AUG) has a story on this. Registration is usually required, so text follows . . .
Article URL: http://www.dallasnews.com/sharedcontent/dws/dn/lat estnews/stories/081905dnmetnanosheet.1c9439ac.html
Video URL: http://www.dallasnews.com/s/dws/spe/2005/nanotech/
---------
LITTLE CREATION, BIG STEP
UTD team's chemical ribbons could assist many high-tech dreams
09:01 PM CDT on Thursday, August 18, 2005
By SUE GOETINCK AMBROSE / The Dallas Morning News
Scientists from the University of Texas at Dallas have spun yards of chemical ribbons that are lighter than a feather but stronger than steel a significant advance in the rapidly growing field of nanotechnology.
(Picture: LOUIS DeLUCA/DMN University of Texas at Dallas scientists (from left) Mei Zhang, Sergey Lee, Ali Aliev, Anvar Zakhidov, Shaoli Fang and leader Ray Baughman took part in the research.)
The development could lead to a host of high-tech applications that scientists have dreamed of but haven't had an easy way to create: futuristic clothes that light up, store energy or blunt bullets; car doors that are ultra light, extra strong and double as batteries to store solar energy; flexible, filmy light bulbs that are thinner than a human hair; artificial muscles for robots; and solar sails to propel space vehicles.
A report describing the chemical ribbons, created from tiny carbon tubes barely visible to the human eye, appears in Friday's issue of the journal Science.
"This is a big deal, a real big deal," said James Tour, a chemist at Rice University in Houston, of the new study. "Every paragraph is a gold mine."
The ribbons are created from carbon nanotubes, filaments about one-five-thousandth the width of a human hair. At the atomic level, the nanotubes look like cylinders of chicken wire. Because the nanotubes, like diamonds, are made entirely of carbon, they are extraordinarily strong. They also conduct electricity.
Scientists had known of carbon nanotubes' exceptional properties but had struggled to easily convert them into convenient forms. Last year, the UTD scientists, led by chemist Ray Baughman, had spun the nanotubes into yarn. Other scientists had created small sheets of nanotubes, but their process was cumbersome. DallasNews.com/extra
"The value of this invention is to make it into sheets," said Ned Thomas, a materials scientist at the Institute for Soldier Nanotechnologies at the Massachusetts Institute of Technology in Cambridge. "Clever people will take those sheets and put them into technologies that have yet to be invented."
THE PROCEDURE
Making the ribbons is quite simple, Dr. Baughman said. The UTD scientists started with a "forest" of nanotube trees, about one-third of a millimeter high. Then they stuck a Post-It note to one edge of the forest and gently pulled away. The nanotube trees were drawn out, and as the researchers kept pulling, the trees stuck to each other side by side, forming a long, wispy and transparent sheet.
Sheets more than a meter long, about two inches wide, and less than one-thousandth the width of a human hair thick can be pulled in less than a minute, by hand in the lab, Dr. Baughman said. The process easily could be industrialized, he said.
"There is no limit on how wide they can be," Dr. Baughman said.
The ability to convert carbon nanotubes into such a useful form will be a boon to many small companies trying to use them to create newer or better devices, Dr. Thomas said.
"Nanotechnology needs this," he said. "It's been hyped, and there's been a lot of expectations."
Dr. Baughman, who said the university and a collaborating Australian national lab have
And it has absolutely nothing to do with the technology. It's all about the economics.
A space elevator is going to require a truly civilisation shaking level of investment by a country. Then, once it's built that investment has to be amortized over it's lifetime, but wait, it only has two end points and it takes a certain amount of time to load and unload a vehicle of cargo and passengers, it takes a certain amount of time to travel the distance up to orbit. These two fundamental physical limitations will mean that a space elevator will never be able to pay back the investment. It's always going to be cheaper to load a cargo on top of a rocket booster and fire it up.
Deleted
So many uses... perhaps we should start working on the vaccine against the bug that eats the stuff.
its *them* who could be telling you this...
how can you ever fully trust nanotube sheets, maybe they actually conduct and amplify your thoughts making it even easier for them to pinpoint you deviants out there and eliminate you... or just listen to your thoughts... everyone has tinfoil, only deviants will have nanotube berets.
Gravity Sucks
I bet spider webs are still stronger.
Note to mods: I'm probably being sarcastic.
Thanks a lot, jackass. Now I have to go listen to Price all day to burn that song out of my head.
There are two types of people in the world: Those who crave closure
WTF is Strength normalized to weight?
Specific strength is the term they are looking for, second it is normalized to mass, not weight.
Suggest to me someone with little science/engineering background "wrote" the article, and just listed off the interesting stuff they 'heard about nanotubes'
If this stuff is so resilient, NASA should really research a coating of it over the Shuttle tank foam that keeps falling off.
Artifical Intelligience is no match for natural stupidity.
... that Nanotubes are to materials as XML is to software?
The AACS key is NOT 0xF606EEFD628B1CA427BEA93A9CA9773F
Well, no. That's the whole point. Even if it's serial it can boost you bandwidth per buck a huge lot.
My english is sow-sow. Sowhat?
According to the Science article(subscription required) abstract a stack of 18 sheets had a strength of 465MPa/(g/cm^3) (high strength steel listed as 125 MPa/(g/cm^3)).
They also built an OLED of 500 cd/m^2 with a onset voltage of 2.4V.
make that a billion - it will probably cost you over a hundred million just to realize your dream...
Where's my free iPod!? Until then, I'll settle for a kiss...
Good material for solar powered airships/blimps to jumpstart super cheap air-cargo. nough power to get a good clip and even replenish bouency with hydrogen from ocean/lake.
Yeah, yeah, hindenburg and all. Did any one on that thing die from fire or did they ALL jump out?
A strength-boosting, bulletproof, super-light-weight bodysuit that can change colour and styles, doubles up as a solar battery, washes itself, heats itself up, cools you down, lights up or darkens things, temporarily blinds and electrocutes hostiles (causing paralysis), cooks food, has jetpack-like capabilities to take you places, remembers everything that happens to it and can replay it (like how much pressure in what places occur when you are hugged), has an in-built calculator, browser and email client, calendar, alarm clock, 100 Megapixel camera with flash, stores addresses, phone numbers, email addresses, and bookmarks (and can communicate using them via speed-of-light methods), can play computer games, movies, music, makes you invisible, all controlled by your thoughts alone, and it will only costs 3 pennies from a wide range of stores.
Maybe, but with a description like this...
How big are your bucks? A space elevator will cost trillions. It'll require thousands, maybe tens of thousands of individual lifts to pay for it. In the meantime, rocket launches are just getting cheaper and cheaper. The Russians and commercial operations like Sea Launch can launch for a miniscule fraction of the cost of a space elevator.
Deleted
Why make a billion when we could make...(dramatic pause) ... a MILLION?
You're bound to be unhappy if you optimize everything. --Donald Knuth
3d nanoprinters that will eat you once your microsoft OS gets the latest virus.
VLC FOR MAC IS DYING! IF YOU DEVELOP, PLEASE SAVE IT!!
> A jacket that makes a Faraday cage around your body
I obviously don't know enough about Faraday cages, but would it have to cover you "completely?" Like could you have openings for hands, feet, and especially face with it still working as intended?
Well, the greatest danger to the clean, sterile environment is carbon-based, you know...
It's also gas based. You may also want to look up the carbon cycle
try { Signature mysig = new CleverAttempt(); } catch(NonCleverSignatureException e) { postanyway(); }
Of course, if you had been part of the effort, it would've happened twice as fast. But you obviously had other priorities, and I'm sure I speak for all of us here when I express my deep appreciation for taking a little of your precious time to share your insight with Slashdot.
I'm no chemist or engineer, I don't know what potential carbon nanotubes have or don't have but whenever I read an article that seems to promise everything, I figure it is about 95% hyperbole and wishful thinking.
I'm pleased to see that these things are getting ready to move into a sort of production phase but really wonder what applications they will find themseves in? If some conventional prduction method produces a product of acceptable quality, I don't see carbon nanotubes making much of a dent in these products. The reason is simple, new technologies are always expensive in comparison to existing technology. Where I'd expect to see them shine is where some feature of the nanotube makes something that was previously difficult, expensive, or impossible to become affordable and easy to produce.
Since I like to play with composites, I hope that they will come out with some fabrics that can be used in conjunction with epoxy to produce exceptionally strong, light weight structures.
Rocket launches will never be as cheap as the energy required for lift. Rocket launches cannot (without an absolutely insane level of production....such as with advanced nanotechnology), in my opinion, provide the kind of routine heavy traffic needed by a large spacegoing civilization engaged in large scale space industry, mining, and colonization (unimportant to you I'm sure).
If you want to just launch lots of probes, sats, and maybe have a few space stations....sure, hey rockets are awesome. But if you want to build a large spacefaring civilization you need some real infrastructure. This means megascale engineering projects like a space elevator. There are other possible systems that could be built to get us this...but it looks like the space elevator is the one that's closest to getting done. And the costs don't look to be as expensive, for a "starter elevator" as you are assuming. Private corporations are looking into this, and talking billions, not trillions...The description sounds so good, it's like an April fools joke... I'm glad it's not April 1st !!
maybe tens of thousands of individual lifts
Two initial lift and a stitcher/climber
The Plan
All other materials are lifted using the initial 20cm ribbon cable
Okay it looks like this could be used anywhere that you currently use Carbon Fiber. I can hardly wait.
Super strong light weight helmets.
Homebuilt aircraft.
Bicycles.
It just goes on and on.
The fact it is transparent, conductive, and absorbs microwaves makes me think that we will see a lot of it uses for RAM coatings on ships and aircraft.
I can also see it being used for anti rf wall paper and and windows in secure buildings.
All in all very cool.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
From the article:
... With this method they can produce nanotube sheets at up to seven meters per minute, ...
Assuming the product eventually exceeds 100 GPa, at this rate it would take over 27 years to produce a 100,000 km ribbon in one piece. Since that timescale would be impractical, I figure they should aim for at least a meter per second, which would allow them to do it in a little over three years instead. On the other hand, they could also, for example, set up 30 production lines to work at the current speed, run them all for about a year and then glue the segments together using the extra length for overlap. However, that would add extra volume and make it heavier (remember that the first ribbon has to go up on a rocket).
You're probably trolling using a phrase like "will always be cheaper" but since the moderators seem to think your post is serious I'll bite.
Launch 100 rockets at 100 bucks per rocket and you've paid $10,000. Launch 100 elevators at at $1 per use and you've paid $100. Point is, which method is cheaper depends on the relative costs of the two methods.
Space Shuttles run $1 billion per launch. Since we don't know how much the elevator will cost to build or operate, $1 per launch is as good a number as any right now.
Without any calculations and relatively little knowledge in the subject, I wouldn't be surprised if the energy needed in a shuttle launch and the energy needed in an elevator launch were just about the same. And isn't the biggest cost of launching the fuel (energy) to get out of the atmosphere?
You'll also have to take into account time, since time is money. I'm sure shuttles reach orbit quicker than an elevator would.
In the end, I think relative costs would be about the same. Then other factors such as safety, reliability weigh in.
"Action without philosophy is a lethal weapon; philosophy without action is worthless."
Pictures, assembly instructions, and... user testimonials!
"Worker bees can leave
Even drones can fly away
The Queen is their slave."
I wouldn't rely on a tabloid science article for the current status of technology.
I do find it odd that you'd expect someone who doesn't know that weight and mass are different would know what 'normalized' means.
Depending on the target audience I would have said either
High specific strength or
Good strength/weight ratio
I'll stand by my initial statement that this is a junk article.
I heard that the last NASA Shuttle launch was ~280 million (probably not taking into account the huge sunk costs they have incured..), and recently the largest .com satelite thrown into orbit cost 250 million.
1950's ...
It's a floor wax ... It's a dessert topping!
-- "It's not stalking if you're married!" My Wife.
We know buckyballs tear fish brains apart. What does this stuff do? Have biological experiments been run yet?
LS
There is a fine line between being a cultivated citizen and being someone else's crop. - A. J. Patrick Liszkie
Well, unlike the materials you mention, nanotubes consist of only one element, and a well known element at that. The only real possible danger is the asbestos danger (as in, small particles coming free and damging lungs). The possibility of this, however, seems narrow due to the chemical properties of the nanotubes. They do not stick well, unlike asbestos, and they are made purely of carbon, which, in theory, the body can absorb.
I suppose there is the possibility of other dangers unlike any seen before, but if we halted advancement for every risk, we would not exist, as even without technology life is full of risk (some would say more without all of our technology).
I remember a story posted a few months ago that spoke of nanotubes. It said something about a resonance frequency. If this is true (the article didn't seem to address this), then what is to prevent people from emitting the waves, somehow. Say, if you were wearing these threads woven as a flak jacket? Or, if they were creatable strong enough, I would not ride the orbital elevator if someone's ringtone could cause the thing to just vaporize around me... even though, it would be the way to go.
This sig isn't original enough, it's time to come up with something witty...
Well, those carbon-based lifeforms that pose the greatest threat to a clean, sterile environment also tend to spew a lot of hot air...
You can even cut a tin can with it!
They don't eat cereal in space. They drink Tang!
No holes for body parts to protrude out of, but if the holes are much smaller than the wavelength and don't have a conductor down the center to act as a waveguide, it should work just fine. I.e., a very fine mesh that allows your body (and lungs!) to breathe is acceptable.
Kneel Before Christ!
... the "tingling" tells you it's working!
Height: 38U, Weight: 0 Newtons, Eyes: #0000FF, OS: Gray Matter 1.0 (Alpha)
This month's IEEE Spectrum features an article by Bradley Edwards who studied the near-term feasibility of a space elevator under a grant from NASA. His conclusion is that it could be accomplished in as little as 10-15 years and for as "little" as $10B (meaning little enough that there are several individuals on Earth who could fund it privately). Of course, the major technological limitation is the nanotubes. He suggests "spun" nanotubes (like yarn) or nanotube composites (and he contends that if one of these broke near the top, it would not be the end of life as we know it -- it's a ribbon that would loft gently down to Earth and burn up in the atmosphere). He even addresses storms, terrorism and space-borne threates. It's a good article and somewhat technical (written for engineers). His conclusions are quite credible, and probably more informed than your average Slashdot debate.
Today's Sesame Street was brought to you by the number e.
There was a movie, filmed about 50 years ago called "The man in the white suit".
The man invented an indestructable type of polymer string which was used to make cloth. The cloth also never got dirty. The people chased him because the invention promised the complete destruclion of the clothmaking industry.
Well, this invention reminds me of that movie.
You are right... if your space is asymptoticaly flat. In an arbitrary space it is not necessarily true.
Rockets cost ~$1000/kg to get to LEO (the space shuttle costs ten times that). A space elevator will lift the same to GEO for a fraction of the cost. The energy required (estimated conservatively) is about 150 MJ/kg, or about 50 kWh/kg. Energy prices currently run 5 to 10 cents per kWh, so we're talking an energy cost of about $5/kg. Let's say the total cost per kg for the space elevator is five times that, in keeping with other modes of transportation, for a total cost of $25/kg. It could easily be lower than that.
So if a space elevator cost a trillion dollars (enough capital for 4000 shuttle flights) it would take about a billion kg lifted to make the difference, although again, this is lift to GEO, not LEO, so I'm being very unfair to the space elevator. This is equivalent to 35,000 shuttle flights with full payload (to LEO).
Bottom line: the space elevator won't be built until the cost is well under a hundred billion dollars, but this is quite reasonable. There is no reason to believe that a trillion dollars is required. Most of the cost is in the rockets to carry the first assemblers up to GEO with sufficient material to run the first strand down to Earth. After that, assembly can be done from the ground.
So the relatively low cost of rockets is actually going to make the space elevator more likely in the long run, not less.
Blasphemy is a human right. Blasphemophobia kills.
Man, I can't believe a discussion was started with the word 'producable'
Wouldn't it be Producible ?
A suit of this stuff will shrug that sort of thing off like water off a duck's back. It's conductive. If done right, it'll act like a Faraday Cage and the RF will never impinge on your tissues except where you've got exposure out of the suit's confines...
I am not merely a "consumer" or a "taxpayer". I am a Citizen of the State of Texas
are you implying that there will only ever be ONE space elevator.
I venture that once the first elevator goes up, hundreds or thousands more will be deployed at a fraction the price of the original.
so, are there hundreds of rocket launces every day?
and explain again why a rocket - which is singular - is parallel.
There is a higher calling than space elevators... Condoms
People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf.
If I can remember correctly, the biggest hurdle in the development of the X-33 was the strength of the composite LOX tanks. Apparently this is exactly what they need, just wrap this ribbon around the tank and double the storage capacity. Hell make the whole spacecraft out of this stuff.
Why couldn't they wrap the exterior fuel tank on the shuttle so that it would not lose any insulation on take off.
This link has been posted a billion times on slashdot already, but here it is again. 10 billion dollars for the first elevator, and roughly 3 billion apiece for the next ones. I have a feeling that construction on the space elevator will begin in the beginning of the next decade, though I'm not sure who will build it. According to this survey nanotubes are already produced in quantities of hundreds of tons, with production in all four regions with space-launch capability. Most likely we'll see two competing elevator projects, with the chinese and NASA-ESA as the competitors.
Does that mean that energy is not conserved in a non flat spacetime in GR?
echo -e 'global _start\n _start:\n mov eax, 2\n int 80h\n jmp _start' > a.asm; nasm a.asm -f elf; ld a.o -o a;
No, the GR field equations state that the stress-energy tensor is proportional to the Einstein curvature tensor - which has a divergence that is identically zero in any spacetime. Even with a cosmological constant different from zero, since the metric has zero divergence the conclusion still holds.
Those who can make you believe absurdities can make you commit atrocities. - Voltaire
You're way off here, did you read the article? Are you not agreeing with the article's breakdown of cost? He lays it out pretty convincingly in terms of $/kg. Can you provide any sort of data like the author has provided that shows it will cost more than the author has stated? Rockets have a pretty serious limitation on the mass that can be lifted. There are things that "cheap rocket flights" just can't do, at ANY cost.
I you could build a strong enough sphere out of this stuff and pump out all the air, would it have more lift than the equivalent volume of hydrogen?
- Molded Nylon - 75 MPa
- Plain carbon steel - 450 MPa
- 4130 Cromoly steel - 1110 MPa
- Dupont Kevlar 49 - 3620 MPa
- Carbon Fiber - 4000 MPa (approx)
As you can see, carbon fiber is about 4% as strong as the target, which tells you two things: First, nanotubes kick butt. Second, this elevator is not right around the corner. Sure they're getting good at making individual fibers, but the weave will not carry the same stress as the individual fibers, and we have to find a way to work around that.It sounds like to me they should use this stuff to wrap the foam insulation onto the space shuttle external tank so it won't fall off. Then they can think about using it for space elevators.
Because by the time this stuff gets into commercial production and tested vigorously by government scientists, there won't be a space shuttle any more.
Democrats or Republicans. They are both taking us to the same place and they are not afraid of us anymore.
Where the heck are you getting "Trillions" from???
The highest estimate I've seen has been 80 billion, and that was years ago.
Building the first working space elevator will be a huge event in the history of mankind. It will be the gateway to the universe.
Democrats or Republicans. They are both taking us to the same place and they are not afraid of us anymore.
When I said "zero divergence" I was loosely referring to the fact that the contraction of it's covarient derivative vanishes. This, though, is surely local conservation of energy? Which is all I am claiming. The extra terms you have involving the connection coefficients do stop the "usual" divergence from vanishing, but that is hardly surprising - gravitation (i.e. curvature) influences the matter fields!
Those who can make you believe absurdities can make you commit atrocities. - Voltaire
And thus you prove the purpose of trolls. Without trolls we could not get you post and it has been a wile since I have seen such a tactful ridicule here on /.
Thank you.
I mod everyone down who says "I'll get modded down for this." I hate to disappoint.
Wow! Overrated...... Hey Moderator dude RTFA. Ray and Anvar are the guys running this show.
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..IF DONE RIGHT...
Considering that you'll have heating, you'd change the thermal conductivity so that unless you're totally bathed in microwaves, you're not going to have issues (HINT: if you're bathed in microwaves such that it's going to bake you in that sort of armor, then you're going to get baked in a tank or any other armor you'd might field- the energy densities in question are such that there's little to shield you unless you can shed the heat... This stuff could shield you against riot control uses of Microwave energy...)
I am not merely a "consumer" or a "taxpayer". I am a Citizen of the State of Texas