Catch up on stories from the past week (and beyond) at the Slashdot story archive


Forgot your password?

Comment Re:Colo? (Score 3, Informative) 285

I am using a ReadyNAS Duo running Free BSD. The NAS is in a cupboard a a friend a few houses away.

For syncing I use Unison. The initial backup was created onsite. Every night I run an incremental backup. When local drives are destroyed it is only a short walk to get my data back.

It all works like a charm.

Comment Re:Open set it is! (Score 4, Informative) 248

GP has already used all the supposed finite number of prime numbers in constructing his contradictory bigger prime.

The proof constructs a number that is not divisible by any of the prime numbers in the set of all prime numbers. Therefore it proofs there are an infinite number of prime numbers. The conclusion the constructed number must be prime is wrong.


Comment Re:Cool idea, but never happen... (Score 1) 368

If the US companies are stalling this development I bet soon enough some Japanese or Chinese companies think is is a great idea and start selling it all over the world. Just like electric cars, pv solar cells. US companies may even try to block import of those great power supplies and make the US into some backward country where they are still burning fossil fuels for energy while the rest of the world moves on.

Comment Re:A linear induction motor is not a railgun. (Score 3, Informative) 314

To accelerate a 100000 pound object to 240 mph requires an energy of 260 MJ (sorry I converted all units to SI before I started calculating so you have to convert it back to BTU or kcal or whatever the right unit for energy you want to use yourself). Assuming a linear acceleration over 300 feet to 240 mph gives an acceleration time of 1.7 s. This results in an average power of 153 MW. AFAIK there is no electrical turbine that will supply an extra 153 MW at the flip of a switch. Electrical energy has to be stored somewhere to let the catapult work.


Submission + - It's life Jim but not as we know it, (

Nyh writes: NASA will hold a news conference at 2 p.m. EST on Thursday, Dec. 2, to discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life. Astrobiology is the study of the origin, evolution, distribution and future of life in the universe.

Comment Re:neat (Score 1) 146

They run at gigahertz speeds, which implies nanosecond timings. A flywheel with decent mass spinning a million RPM is only four orders of magnitude away from the speed of light.
It all depends.

Speed of light: 300e6 m/s
Speed of micrometer scale graphene flakes spinning at 60 million rpm:
2*pi*1e-6/1e-6 = 6 m/s = 21.6 km/h
I think you can get any material spinning at 60 million rpm at micrometer scale. Tensile strength is not very important at these speeds.

It is a nice trick though.


Comment (Score 1) 119

At the moment I think it's aimed at typical commuting distances. 360 km is a very long ride! (How long does that take?!)

Actually it is close to 400 km (A120, A12, London city center, A4, A30, A303). My best time is 14 hours, worst 20 hours. For the return journey I allot 24 hours because I don't want to miss the ferry. But 400 km isn't that a big distance when you train for rides like Paris-Brest-Paris or London-Edinburgh-London.


Comment (Score 2, Informative) 119

Even in the Netherlands we do not have a satnav app for cyclists on the iPhone. Route for cyclists can be done by the excellent 'fietsrouteplanner' planner from the Fietsersbond ( This great planner has lots of options and biker profiles (like shortest route, avoid busy traffic, green route, social safe route, racing cyclist, etc.) but once you are cycling it is quite useless. The route is static, has no rerouting when you choose an other route due to roadworks or just because you felt so.

I immediately tried out this app but was a bit disappointed. I cannot plan a route from Harwich to Exeter, a route I have cycled multiple times to visit family in England.


All I ask is a chance to prove that money can't make me happy.