Well, a class in quantum physics ain't going to help you. A class in general relativity might though.
The basic deal is that in the presence of extremely strong gravitational field movement in space along a certain path results in a movement in time. This is what is meant by the sentence: 'The idea is to start with flat spacetime, choose an arbitrary curve, and then deform spacetime in the immediate vicinity in such a way that the curve becomes a timelike geodisic, at the same time keeping most of spacetime Minkowskian'.
I remember (back as a physics undergraduate) learning a pretty cool visual explanation of this with little spacetime cones (the 45 degree edge of the cone representing light speed). The idea was to tip the cones over. Or something.
Anyway, Alcubierre's initial formulation of this space time can only be created by a ridiculously strong spinning gravitational field. I seem to recall something about a bloody huge sphere of material the density of a neutron star spinning so it's surface is going at 0.999c. Massive it was.
There are other problems with the Alcubierre geometry, namely basic things like electromagnetism gets buggered up, it requires lots of negative energy (think of negative pressure rather than straightforward energy) and anyway as soon as you start going faster than the speed of light it becomes physically impossible (with this geometry) to go faster than the speed of light. Go figure.
So this Belgian bloke has come up with a absolute wheeze: keep the surface area of the warp bubble you create really small but expand its volume to something you could reasonably fit a Volkswagen Polo into. Try this at home and you may run into the slight problem that volume usually increases to the 3/2 with area. Not a problem because this dude's a cosmologist, he's got all the paper and pencils he needs, and it always rains in Leuven so he's got nothing better to do. Check out eqn (4), it's a beauty.
Working through the maths he comes up with some numbers and - suprise - his new warp geometry requires much less negative energy than the Alcubierre geometry (which required rather more negative energy than the total positive energy in the universe, just to produce a warp bubble that could have been described as 'cramped and bit stuffy' by a vole). In fact using some sensible (i.e. off the top of his head) figures, he finds that you only need 3.4 grammes of negative energy.
The problems of where do you get the negative energy from, the massive densities involved and how do you get a macroscopic object into a bubble with infinitesimal surface area of course remain.
The largest spy station in the world (run by the NSA as part of the UKUSA agreement) is at Menwith Hill in North Yorkshire - some enterprising bods have set up balloon tours over it - the balloons are fully equipped with directional mics, video cameras etc, check out here here.
I think the real thing that pisses people off with the UKUSA agreement is that it is used by governments to spy on their own poeple. For example, in the UK it is illegal for the authorities to monitor communicatios without direct permission of the Home Secretary. So they get the US NSA to do it for them. Similarly in the US, the NSA cannot legally monitor domestic communications between American organisations - so they get a bunch of British GCHQ spooks based in Fort Meade, MD to do their dirty work for them.
Basically, having foreign military on your sovereign territory sucks and is open to abuse. I have no idea why Europeans (and North Americans) have stood for it for so long.
Umm, I think you mean expatriate... A person who has lost all respect/love for their country of citizenship is an ex-patriot. A peson who lives outside of their country of citizenship is an expatriate
Oh, you mean like Boeing, Lockheed Martin, Hughes and the rest of the (corporate) welfare leeches? Defence Research Contracts (and NASA contracts, of which I have personal experience) are a licence to print money. For example, Hughes/Raytheon is/was contracted to build the information system (DIS) for the EOS series of satellites. The DIS nver worked and has effectively been scrapped but Hughes never paid a cent back to the US taxpayer. Why? Because they owned the congressional committee who drafted the contracts. Happens every day. US defence/research contractors would go tits-up in a month if they had to compete in a real market rather than just live off US government handouts. Yup, that YOUR money folks.
Basically allows you to do process migration on a cluster. A Beowulf cluster (which we all know about) runs processes on each node which communicate by messaging. However, you can't treat the whole cluster as an SMP machine and simply start a process 'on the cluster' and hope it goes to the most suitable node. This is exactly what MOSIX does - it allows you to treat your cluster almost like a big, low bandwidth, SMP machine (AFAIK).
...if you want to go somewhere with a booming high-tech economy, high quality of life and a friendly and relaxed attitude. Ireland is currently undergoing net immigration (for the first time ever) - as tech workers swarm there from all over Europe and even N. America. They have really nice tax breaks and it is not too hard to get a work permit. In fact you only need to have a single Irish great-grandparent to claim Irish citizenship - which means that if you are American you have a very good chance of getting citizenship.
Of course, once you have Irish citizenship you have an automatic right to reside and work in any of the 15 European Union countries - so if you get bored of Eire you can take yourself off to Denmark, the Netherlands, Italy, UK, wherever...
Nick (whose trying to decide between the UK, Ireland, France and the Netherlands when he goes back to Europe)
We have a RedHat 5.1 box used for writing CDs. Initially we just used scp to copy files over to the linux machine to burn to the CD. Then someone suggested mounting directories off our SGI O200 server so that we could write the disk image directly to the local disk off the NFS drives. Result? Every time we tried this, the O200 was dead within an hour. Any file access, either for other (IRIX and Solaris) NFS clients locked up the process making the request. Even typing 'ls' in a local directory when logged in to the O200 hung the shell. The only way we could get things back was to reboot - we also had to reboot the NIS domain controller (a Sun).
Unfortunately, IKONOS-1 is just the latest in a long sequence of failed remote sensing satellite launches. The biggest blow to the RS community was the launch failure of Landsat 6 a few years ago, the loss of Lewis in 1997 was also extremely depressing. Luckily, Landsat 7 launched succesfully last week. The next major RS launch is that of EOS AM-1 in July - if this isn't successful I'm out of a PhD:-(
The IKONOS-1 people aren't too bothered, these things happen and of course they were fully insured - IKONOS-2 is complete and will be launched by the end of the year. My theory is that the launch was disrupted by SPOT:-)
As far as the guff people are talking about spy satellites - remote sensing imagery has a THEORETICAL resolution of about 15cm. This is imposed by atmospheric disturbance. Spy satellites are designed for this resolution but the resulting imagery rarely approaches it. The main difference between spy satellites and RS satellites is that the spy satellites can execute orbit transfers a limited number of times (before they run out of propellant), resulting in an increased revist rate. They also of course do stereo (like SPOT). Unfortunately the military aren't exactly clued on how to analyse satellite data - we're talking transparencies, light tables and magic markers - don't believe the stuff you see in the movies.
Actually, the allies in the gulf war ended up buying a shitload of imagery from SPOT simply because the spy satellite stuff wasn't up to scratch (not multispectral, images too small and too high resolution to go launcher-hunting in the desert). The French government tried to lean on SPOT to give a discount but they actually upped their rates realising they had a monopoly...
This is a bit of a troll because you're talking about private schools though aren't you? I was asking for a comparison of like with like - public schools in the US and state schools in the UK.
I agree - a really great article. As a non-American I had never given a second thought to the US school system until I started reading articles on it following the Littleton massacre. The system of cliques, prejudices and the social ostracism of those who do not conform is indeed sad to read about, especially as it occurs in a country that prides itself (rightly) on its classlessness.
I would be interested to hear from any UK posters whether this atmosphere has developed in schools there - it certainly didn't exist when I left school (12 years ago).
The only concillation one can give to those who have a hard time at school is that, although it may seem like the whole world now, as soon as you leave you'll realise how unimportant it all was and how pathetic those children who humilitated you really were. Small concillation, I know.
Well being a monarchy doesn't mean you can't have a Bill of Rights - England has had one since 1689. I believe though that Australia is the only English common law country in the wold that doesn't have a Bill of Rights. Odd that. Mind you, they are signatory to the UDHR and (for the most part) abide by it which is more than can be said for some other signatories. Yes, I'm looking your way USA...
Nick
Because they can't buy it, and they need it most
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Linux in South Africa
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· Score: 1
I wouldn't really class the UK, Germany, Russia, Canada and Japan as "moderately affluent, or trying to appear so". Not only does it sound a little snobbish but it's just plain wrong. Four of those rank in the top 7 richest countries in the world (i.e. are very affluent). Russia, as you may have figure out if you have watched the news at all in the past year, does not. In fact South Africa has a higher ppp GDP per capita than Russia - by over 30% ($6200 vs $4700)
I think your views may have been molded somewhat by the media. While it is true that there is less social sigma attached to recreational drug use in the UK, particularly amongst professional and college-educated citizens, the UK does not have nearly the levels of drug abuse of the US, particularly with regards to crack cocaine. Cocaine is still an expensive drug - a diversion for those in the music, fashion and advertising industries. In some deprived, high-unemployment areas there is a problem with heroin, but the destruction of entire neighborhoods associated with crack cocaine and its attendant violence in the US does not exist (this may have something to do with the lower availability of firearms).
Another interesting aspect of UK/US comparison is that notions of privacy make it virtually impossible for employers in the UK to use drug testing on employees. Considering the hypocrisy of drug testing this is probably not a bad thing - I'm sure that far more money is lost to firms by employees being hungover than smoking a joint over the weekend.
Well, there's a difference between POSTing a bunch of processors and actually scheduling processes on them in an effective way. From what I read, the current 2.2 kernel doesn't scale well beyond 8 processors. Sure, it booted on a 16 processor Sparc but whether it makes effective (or any) use of those processors is a different matter entirely.
Because Beowulf machines aren't computers in the normal sense. Linux doesn't really support more than 8 processors on a shared memory machine - such as a Starfire or O2K. Beowulf clusters are exactly that - clusters of computers, each having their own processor, memory and kernel, and connected by a high speed network.
To use this as something approaching a supercomputer you have to custom write your applications using a message passing library such as MPICH. An ordinary program, even a multi-threaded one, will not show any speedup on a cluster as the standard Beowulf model does not support process migration (although MOSIX does this). Even with process migration, you still don't have shared memory so things are a lot slower than a real supercomputer.
If they do this with UK companies they are in breach of the Data Protection Act 1984(?). Admitedly, the majority of UK companies are registered with RIPE rather than Internic/NSI but those that have a.com domain in addition to.co.uk will also be registered with the Internic.
Any Brits want to comment on this and perhaps point this out to NSI?
Nick
GOOD!!! TOO MANY DAMN PEOPLE!!!
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Killer Asteroid
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Wrong again. My mother is French and half my family live in France. Nick
GOOD!!! TOO MANY DAMN PEOPLE!!!
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Killer Asteroid
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· Score: 1
And you're an ignorant racist idiot. If you want to cut down on pollution you have to look no further than North America and Europe---we are responsible for the vast majority of pollution. If you want to cut down on pollution, walk or cycle to work instead of sitting your fat arse behind a steering wheel, don't keep your house so hot in the winter and so cool in the summer and try to eat less meat. It's simple really. Oh, and try to watch your mouth. Nick
Very informative. I still fail to see what relevence this has to the case at hand. You assert that "most countries follow the Lanham Act" which I find extremely hard to believe. For example, the UK's copyright and trademark legislation predate that of the US considerably. Germany does not have a common law system - it uses a civil code. So I fail to see how you can even begin to draw analogies between the two systems.
Until someone can provide us with some facts regarding German law in this area this is all speculation.
The saddest thing in the article is that the plaintiffs have named several students at the school in the suit - presumably friends of the child who murdered their children. I can't believe that anyone in their right mind, however traumatised by the loss of their loved ones, would name classmates in a compensation suit.
What a sad, sad world we live in. My mother's a lawyer, my partner is about to qualify as one and I know that some (most?) lawyers are decent people, but when you read of cases like this it makes you lose faith in the whole profession.
CNN's coverage of the Kosovo crisis has been appallingly poor. Slow, out of date, American-centric information. Are they the only news organisation yet to realise that the pentagon has nothing interesting to say on the subject and all the real news is coming out of NATO headquarters in Brussels?
Try the BBC here if you want a decent, up-to-date web news source. Another nice thing about the BBC site is that they use RealAudio/Video for all their feeds rather than messing about with about 6 different formats as CNN are want to do. BBC News 24 (a 24hour news cable channel) is always available over the web here. You can also get the news in Russian, Spanish, Arabic, Cantonese, Mandarin, Japanese, Serbian, Albanian, Macedonian and a few others.
Nick
P.S. John, scared Arkan is going to sue you with that "alleged" in there? Arkan is a brutal, murderous warlord, who once referred to himself as "the Hitler of the Balkans". He was responsible for the death of thousands in Bosnia and he's going to do the same in Kosovo if we let him.
No - I've never owned a car. Never felt I've needed one and in my current incarnation as a graduate student I can't afford to own one anyway - hence my post querying how one could own a car and still plead poverty. However, as my fieldwork has been in Indonesia and E. Africa, my definition of poverty is possibly at variance with that of some westerners... Nick
Slashdot Mirror
Hey, does anyone remember the 'Future Echoes' episode of Red Dwarf?
Nick
The basic deal is that in the presence of extremely strong gravitational field movement in space along a certain path results in a movement in time. This is what is meant by the sentence: 'The idea is to start with flat spacetime, choose an arbitrary curve, and then deform spacetime in the immediate vicinity in such a way that the curve becomes a timelike geodisic, at the same time keeping most of spacetime Minkowskian'.
I remember (back as a physics undergraduate) learning a pretty cool visual explanation of this with little spacetime cones (the 45 degree edge of the cone representing light speed). The idea was to tip the cones over. Or something.
Anyway, Alcubierre's initial formulation of this space time can only be created by a ridiculously strong spinning gravitational field. I seem to recall something about a bloody huge sphere of material the density of a neutron star spinning so it's surface is going at 0.999c. Massive it was.
There are other problems with the Alcubierre geometry, namely basic things like electromagnetism gets buggered up, it requires lots of negative energy (think of negative pressure rather than straightforward energy) and anyway as soon as you start going faster than the speed of light it becomes physically impossible (with this geometry) to go faster than the speed of light. Go figure.
So this Belgian bloke has come up with a absolute wheeze: keep the surface area of the warp bubble you create really small but expand its volume to something you could reasonably fit a Volkswagen Polo into. Try this at home and you may run into the slight problem that volume usually increases to the 3/2 with area. Not a problem because this dude's a cosmologist, he's got all the paper and pencils he needs, and it always rains in Leuven so he's got nothing better to do. Check out eqn (4), it's a beauty.
Working through the maths he comes up with some numbers and - suprise - his new warp geometry requires much less negative energy than the Alcubierre geometry (which required rather more negative energy than the total positive energy in the universe, just to produce a warp bubble that could have been described as 'cramped and bit stuffy' by a vole). In fact using some sensible (i.e. off the top of his head) figures, he finds that you only need 3.4 grammes of negative energy.
The problems of where do you get the negative energy from, the massive densities involved and how do you get a macroscopic object into a bubble with infinitesimal surface area of course remain.
Your tax Belgian Francs at work people.
Hope this helps, Nick
I think the real thing that pisses people off with the UKUSA agreement is that it is used by governments to spy on their own poeple. For example, in the UK it is illegal for the authorities to monitor communicatios without direct permission of the Home Secretary. So they get the US NSA to do it for them. Similarly in the US, the NSA cannot legally monitor domestic communications between American organisations - so they get a bunch of British GCHQ spooks based in Fort Meade, MD to do their dirty work for them.
Basically, having foreign military on your sovereign territory sucks and is open to abuse. I have no idea why Europeans (and North Americans) have stood for it for so long.
Nick
A person who has lost all respect/love for their country of citizenship is an ex-patriot.
A peson who lives outside of their country of citizenship is an expatriate
Big difference
Nick
Nick
Nick
Of course, once you have Irish citizenship you have an automatic right to reside and work in any of the 15 European Union countries - so if you get bored of Eire you can take yourself off to Denmark, the Netherlands, Italy, UK, wherever...
Nick (whose trying to decide between the UK, Ireland, France and the Netherlands when he goes back to Europe)
Nick
The IKONOS-1 people aren't too bothered, these things happen and of course they were fully insured - IKONOS-2 is complete and will be launched by the end of the year. My theory is that the launch was disrupted by SPOT :-)
As far as the guff people are talking about spy satellites - remote sensing imagery has a THEORETICAL resolution of about 15cm. This is imposed by atmospheric disturbance. Spy satellites are designed for this resolution but the resulting imagery rarely approaches it. The main difference between spy satellites and RS satellites is that the spy satellites can execute orbit transfers a limited number of times (before they run out of propellant), resulting in an increased revist rate. They also of course do stereo (like SPOT). Unfortunately the military aren't exactly clued on how to analyse satellite data - we're talking transparencies, light tables and magic markers - don't believe the stuff you see in the movies.
Actually, the allies in the gulf war ended up buying a shitload of imagery from SPOT simply because the spy satellite stuff wasn't up to scratch (not multispectral, images too small and too high resolution to go launcher-hunting in the desert). The French government tried to lean on SPOT to give a discount but they actually upped their rates realising they had a monopoly...
Nick
Nick
Nick
I would be interested to hear from any UK posters whether this atmosphere has developed in schools there - it certainly didn't exist when I left school (12 years ago).
The only concillation one can give to those who have a hard time at school is that, although it may seem like the whole world now, as soon as you leave you'll realise how unimportant it all was and how pathetic those children who humilitated you really were. Small concillation, I know.
Nick
Nick
Nick
Another interesting aspect of UK/US comparison is that notions of privacy make it virtually impossible for employers in the UK to use drug testing on employees. Considering the hypocrisy of drug testing this is probably not a bad thing - I'm sure that far more money is lost to firms by employees being hungover than smoking a joint over the weekend.
Nick
Nick
To use this as something approaching a supercomputer you have to custom write your applications using a message passing library such as MPICH. An ordinary program, even a multi-threaded one, will not show any speedup on a cluster as the standard Beowulf model does not support process migration (although MOSIX does this). Even with process migration, you still don't have shared memory so things are a lot slower than a real supercomputer.
Nick
You write beautifully...are you the bastard offspring of John Katz and Spinoza? More!
Nick
Any Brits want to comment on this and perhaps point this out to NSI?
Nick
Wrong again. My mother is French and half my family live in France. Nick
And you're an ignorant racist idiot. If you want to cut down on pollution you have to look no further than North America and Europe---we are responsible for the vast majority of pollution. If you want to cut down on pollution, walk or cycle to work instead of sitting your fat arse behind a steering wheel, don't keep your house so hot in the winter and so cool in the summer and try to eat less meat. It's simple really. Oh, and try to watch your mouth. Nick
Until someone can provide us with some facts regarding German law in this area this is all speculation.
Nick
What a sad, sad world we live in. My mother's a lawyer, my partner is about to qualify as one and I know that some (most?) lawyers are decent people, but when you read of cases like this it makes you lose faith in the whole profession.
Nick
Try the BBC here if you want a decent, up-to-date web news source. Another nice thing about the BBC site is that they use RealAudio/Video for all their feeds rather than messing about with about 6 different formats as CNN are want to do. BBC News 24 (a 24hour news cable channel) is always available over the web here. You can also get the news in Russian, Spanish, Arabic, Cantonese, Mandarin, Japanese, Serbian, Albanian, Macedonian and a few others.
Nick
P.S. John, scared Arkan is going to sue you with that "alleged" in there? Arkan is a brutal, murderous warlord, who once referred to himself as "the Hitler of the Balkans". He was responsible for the death of thousands in Bosnia and he's going to do the same in Kosovo if we let him.
No - I've never owned a car. Never felt I've needed one and in my current incarnation as a graduate student I can't afford to own one anyway - hence my post querying how one could own a car and still plead poverty. However, as my fieldwork has been in Indonesia and E. Africa, my definition of poverty is possibly at variance with that of some westerners... Nick