Follow Slashdot stories on Twitter


Forgot your password?
DEAL: For $25 - Add A Second Phone Number To Your Smartphone for life! Use promo code SLASHDOT25. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. Check out the new SourceForge HTML5 internet speed test! ×

Comment An exponential geometry makes it possible actually (Score 1) 39

This is an amazing published paper on the feasibility of a space elevator.

The big take-aways:
* Decreasing the x-sectional surface area by an exponential function as altitude decreases theoretically allows any material to be used, though the volumes required would be prohibitive for any but the strongest materials, and too steep an exponential function makes the geometries also not practically possible
* A yield strength of 46.5 GPa only requires a max-to-min cross-sectional area ratio ("taper ratio") of 10. A lower yield strength would require a larger taper ratio.

The material in this article has a yield strength of 9.6 GPa which is about 7.2% of the maximum strength of graphene and 20% of the way to 46.5 GPa, and I believe stronger than any bulk material previously manufactured. Reaching 46.5 GPa only requires 36% of the 130 GPa maximum strength of graphene, leaving lots of room for falling short on the actual average yield strength of manufactured product, and also including the required engineering safety factor in the design. And if we still fall short, we have some room to raise the taper ratio.

This TEDx video describes spinning carbon nanotubes to give them more than enough strength, which is basically what these people in this article have done! It also addressed the other concerns of the Gizmodo article. Since this manufacturing is firmly in the realm of engineering, now, I would expect to see a regular rate of increasing strengths in produced materials, as the processes improve.

TD;DR - Space elevator is entirely possible.

Comment Re:Space elevator (Score 1) 39

Actually, no. GPa is a unit of *pressure* -- i.e. the force that can be carried in tension per unit of area. It applies to a material in general, not to a shape or particular amount of a material.

The material they created is not a single nanotube (or 15), it's uncountably many of them spun/squashed into a sheet, with a 9.6 GPa maximum tensile stress (i.e. pressure).

Submission + - Norway Will Switch Off FM Radio in 2017

titten writes: The Norwegian Ministry of Culture has announced that the transition to DAB will be completed in 2017. This means that Norway, as the first country in the world, has decided to switch off the FM network.

Norway began the transition to DAB in 1995. In recent years two national and several local DAB-networks has been established. 56 per cent of radio listeners use digital radio every day. 55 per cent of households have at least one DAB radio, according to Digitalradio survey by TNS Gallup, continuously measuring the Norwegian`s digital radio habits.

Comment Failed to catch on? (Score 1) 626

100 000 to 2 000 000 speakers would disagree with you. Some/many schools use it (e.g. in China, Australia, the UK) as their 1st second language instruction because it's by far the easiest language to learn, which accelerates future language learning. If more schools/regions can be convinced of its scientifically-measured benefits to language learning, it could take off as purely a learning language. Google Translate even has it as one of its languages (and no, Klingon is not in that list).

True, it's not currently the international auxiliary language of choice, but it's definitely *an* international auxiliary language of choice:
- 32nd on the list of Wikipedias by article count (
- stay for free in 90 countries with 1000+ hosts if you speak Esperanto (
- yearly world congress with thousands of attendees, and yearly youth world congress with hundreds of attendees (

I'm still hopeful...

Comment Exactly (Score 2) 265

And that start is growing with double-digit percentages. AND, the majority of new power generation projects in the US (and worldwide) is already renewables (solar/wind/etc), so the trend is only going to accelerate.

Naively projecting that 5% solar power forward at 14% growth per year leads to 50% solar power in 18 years and 100% solar power in 23 years. Of course, that's not an accurate model of what will happen -- a better model would be an s-curve, with the maximum currently unknown -- but it does give a good idea of the rough time scale involved. Around 2 decades until solar power is saturated? That's not so long.

It took a while to get going, with the required government support for the basic research costs, but now this is a self-sustaining free-market endeavour which means it's a trend that now cannot be stopped, thankfully.

Comment Re:Captchas! (Score 1) 98

The truism about Artificial Intelligence is that once a cutting edge problem in AI gets solved, the masses just redefine it as "computer science algorithm". Image recognition was once the leading edge of AI. It's still AI, just not leading edge anymore (unless you're doing something completely novel, like doing it on a quantum computer). Intelligence *is* pattern recognition, of which image recognition is one type.

Comment The most important computing result of our time (Score 2) 98




15 or 20 years ago, I was saying that because quantum computers perform multiple calculations on similar inputs simultaneously, they'll be perfect for the sorts of pattern recognition tasks needed for (artificial) intelligence. And now these smart people have figured out how to do it for the first time, albeit with a miniscule 4 qubit quantum computer.

But since quantum computing capabilities scale according to 2^n, where n is the number of qubits, a 24 qubit computer (i.e. 6 times the size of what they just built, requiring a molecule with 24 atoms) would be 2^20 = 1 million times as powerful as this 4 qubit computer just demonstrated. A 64 qubit computer would be 10^18 = 1 million million million times as powerful as this 4 qubit computer. Good-bye conventional computer encryption. And hello general-purpose pattern-recognition (i.e. the basis for strong artificial intelligence).

My first thought was that a vat of "carbon-13-iodotrifluroethylene" isn't exactly a general purpose computing device -- except that because their control inputs are a stream of radio waves pulses controlled by a conventional computer, it actually is a general purpose computer. And though I'm no quantum physicist / quantum computer scientist, it seems like it would scale reasonably easily: you just need to find larger organic molecules with similarly discrete nuclear magnetic resonance 'channels' (i.e. independently manipulable/separable by frequency).

I am beginning to sense the coming Kurzweil Singularity...

Comment Harmonic Centrality is the wrong measure (Score 1) 53

This article and open rankings work is great, but...

The default ranking we show you is by harmonic centrality. If you want, you can find its definition in Wikipedia. But we can explain it easily.

Suppose your site is Your score by harmonic centrality is, as a start, the number of sites with a link towards They are called sites at distance one. Say, there are 50 such sites: your score is now 50.

There will be also sites with a link towards sites that have a link towards, but they are not at distance one. They are called sites at distance two. Say, there are 80 such sites: they are not as important as before—we will give them just half a point. So you get 40 more points and your score is now 90.

We can go on: there will be also sites with a link towards sites that have a link towards sites that have a link towards (!), but they are not at distance one or two. They are called sites at distance three. Say, there are 100 such sites: as you can guess, we will give them just one third of a point. So you get 33.333 more points and your score is now 123.333.

My intuition:

Incoming links with degree one should be allocated 1 point. *yep*
Incoming links with degree two should be allocated half of 1 point = 0.5 points. *yep*
Incoming links with degree three should be allocated half of 0.5 points = 0.25 points. *NOPE* It actually gets allocated 0.33 points.

This means degree ten links still get 0.1 point? 10 hops away and they're still showing up significantly? That measure is broken. 10 hops away should score vanishingly small... 0.5^(10-1) = 0.001 points is much more reasonable.

The measure shouldn't be 1/n (harmonic centrality), it should be 0.5^(n-1). I would love to see that set of rankings.

Comment Re:Backup Power! (Score 1) 336

That's a good thing to consider, but in general the natural gas distribution system continues to work just fine during a power outage. There's enough stored pressure in the system to last awhile (not sure exactly how long). And the compressors in the system are either powered by natural gas themselves, or they, too, have natural gas generators as electricity backups.

Slashdot Top Deals

"There are things that are so serious that you can only joke about them" - Heisenberg