Of course, you would need to use a sine generator, which you can find in any well equiped electronics/physics lab. I was talking about a very stable oscillator, which is an approximation for a delta-function in the fourier space you speak of. Even if you would have a somewhat crappy sine generator you can use it for interferometry. Remember that all lasers have a finite line-width and thus cannot be considered a monochromatic source if you are picky. That does not prevent you for using them to do interferometry, as long as you keep all your path-length differences within the coherence length.
As an example take an electrical oscillator that has a frequency that is stable to one part in a million (easy to achieve with a crystal). That means that you can have a length of roughly 1 million wavelengths over which the wave is 'coherent', and thus suitable for interferometry.
I agree that comparing it to a laser is a little bit far-fetched, but at least get your facts right while you are ranting:
Can you really call longitudinal waves coherent
Yes you can. Longitudinal/transverse only decribes the direction of the vibration with respect to the direction in which the wave travels. Coherency depends on the stability of the oscillation, that is over how long a time/distance a wave will interfere with itself.
Since you can't amplify atoms, you really can't get a sonic laser
You don't need to amplify atoms, you need to amplify the amount of energy in the oscillation which is a pressure oscillation for sound. I don't know how you would do this for acoustics, but apparently Acoustic lasers do exist.
Re:Take THAT, space science nay-sayers!
on
Glass In Spaaaaace
·
· Score: 1
BS, current lithography systems are not really limited by the quality of the glass. Limits are mainly caused by the diffraction limit, maybe a little bit by the finite accuracy of polishing and measuring the shapes. And remember that a current lithography machine probably has 500 kilo's of glass in it, so it is not really an option to make that in space.
I think you didn't get the concept correlation. Your grandparents having one does not prove that there is no overall correlation.
The infection rate is a nonlinear function (exponential growth and stuff) of user skills, install base, atractivity to malware writers AND inherent security of the OS. People only talk about the last part, while the others might as well explain the differences.
It is always said that there are no viruses on the Mac because it is a better/safer OS. But couldn't this be caused by the type of user alone? I believe there is a very high correlation between buying an Apple and being computer-savvy (or just weird?). Getting infected by a virus usually means some stupid user action (opening an attachment) or not having your patches up to date, both of which are influenced by computer knowledge. This combined with the fact that writers of malware will probably target the biggest install base might be able to explain the different infection rates even with equal number of bugs/level of security. Same story for Linux probably.
Render farm: Especially during the last 3-4 months, november-march, we need online access to a render cluster allowing Blender to render movie resolution frames. Our estimate is that it will require at least 10 systems to render 3 months continuously.
I am not really familiar with the technicallities of rendering, but wouldn't it be possible to use some distributed client model instead of a rendering farm? You could make a program similar to SETI@home that downloads the wire-frame of the scene and sends back the rendered frame once completed. Might be really nice for a screensaver since you actually have a picture to show instead of some alien noise. They estimate 10 systems full-time for 3 months. I guess the same work could be done in the background by 1000 systems in a few weeks.
Some issues that I could imagine: -reproducibility: subsequent frames that were rendered by different clients should look exactly the same. This means that only a project provided rendering core can be used, no tinkering allowed by the user. -copyright (not an issue in this case): suppose Toy Story 7 would use this concept. I guess Disney/Pixar wouldn't be to happy if all the frames were posted online well before the final release. Posting only low-res previews might actually create a big buzz.
Render farm: Especially during the last 3-4 months, november-march, we need online access to a render cluster allowing Blender to render movie resolution frames. Our estimate is that it will require at least 10 systems to render 3 months continuously.
What I meant to say was that it is not a sub-category, but clearly a different category (I'm in favour of 1 not of 4). That said, I think the line between them is hard to draw and depends on your perspective (my 'western european democratic kapitalist' vision, that of a palestinian Hamas member or that of the North Korean government).
Number 1 is a sub-category of number 4, they should be grouped together. Hiding from government censorship is invariably a criminal offense.
With number 1 I was thinking in terms of freedom of speech, e.g. the student movement before the revolutions in Serbia and Ukraine. What is illegal locally might be interpreted as resistance from a global perspective. The border between terrorists and freedom-fighters is a shady/subjective one, but it is a border nevertheless.
The ones I can think of are
1: political groups trying to hide from censorship
2: diplomatic/spy-agency messages
3: P2P
4: criminal/terrorist/pedophile activity
I think most people would agree that the great benefit of such a network is number 1. Number 2 is well accepted practice over the last 100 years, so I think there are not much objections against that. Number 3 might be the biggest selling point of this technique, allthough somewhat ethically debatable. I think this problem will be solved in the next 10 years by either the collapse of the content industry or the availibility of better alternatives.
That leaves number 4. Is there anything that can be done against that or must this be seen as 'collateral damage'?
So BitTorrent is to blame for this one? Just out of curiosity I looked at Emule and it had roughly 900 sources sharing or downloading. I did not download it (i'm not a SF fan), I just wanted to test my recently installed PeerGuardian, which indeed showed a highly increased activity.
I think I saw a documentary at Discovery Channel about some Russian company that already produces the machines for some years (could be this company). According to the show the traditional diamond industry was so worried that they developed an expensive laser system to discriminate the artificial ones from the natural ones. They could then issue a certificate of 'garanteed blood money' (TM). As a hollywood star/gangsta rapper you of course want to make sure that your hard earned money is well spent on some evil warlord somewhere in Africa.
You got your calculation wrong because you don't get the operating principle of the MERIS instrument. It is not a half megapixel ordinary camera that with some magic collects 15*16 bit per pixel (e.g. by taking 15 images in close succession with a changing filter wheel).
As the page on MERIS says, it is a 'pushbroom imaging spectrometer'. 'Pushbroom' means that instead of a rectangular field of view like a normal camera, it has a line-shaped field of view. An image is formed by continuously observing the single line and wait for the the satellite to 'sweep' the whole planet. 'Imaging spectrograph' means that the previously mentioned line is spectrally separated (with a prism or a grating) perpendicular to the line. You then get an image on your CCD where one direction corresponds to the distance along the line and the other is formed by the different colors.
The optics details of the system are here, an description of the CCD is here. If I understand it correctly, one line is 740 pixels wide and the colors are 'binned' in 15 different spectral bands. That gives you 740*15*2=22200 bytes per line. How much that would be per picture depends on the height of the image, which depends on how long you collect data. In principle you could have it sweep the whole planet non-stop.
I did read the failure investigation report (can be found here, search for polar) some time ago and IIRC the most probable failure scenario was a software error involving a single boolean:
MPL was to land under active control (with rocket power, not the air-bag trick). To kill the moter once it had touched down the legs contained contact sensors which were constructed of a pin with a spring, a magnet and a Hall-sensor. The legs were to be extended some time before touchdown.
The problem was the sensors would trigger some intermediate false readings during the leg extension. These false readings toggled a flag, which, once the control system first started looking for contact, immediately killed the engine, having the lander free-fall to death. Clearing the flag after the leg-extension would have saved the mission. The bug was not found because of errors in the software design documents and lack of a system level test. The intermediate false readings were found in a component level test, but its consequences somehow didn't made it in the final design.
Not that physics is always that understandible: A few weeks ago at a day organized by our national physics society I heard a talk by Frank Wilczek, who won this years prize. He was introduced by 't Hoofd, who won it a few years ago, as being an excelent speaker. I think only a small part of the audience (all physicists) had a clue about what he was talking about, most of my colleagues had to resist falling asleep. I saw a talk by the other guy a year earlier and that was not much better.
Mightbe it is because both men did something in high energy/small partical physics, but I think there are not much nobel prizes that could get the kids to study science. Mightbe x-rays or a MRI scanner, but how do you explain the joy of a Bose-Einstein condensate, a high Tc superconductor or some bloody neutrino?
... the most data-intensive physics instrument on the planet. Today eight major computing centers successfully completed a challenge to sustain a continuous data flow of 600 megabytes per second...
I don't know how fair the comparison is, but I think the Lofar project will be a heavy contestant for the claim of the experiment with the highest data rate. It is basically a array of some 10000 radio antennas, spread over the northern part of the Netherlands and Germany. It will be operated as one huge phased array.
The data rate might even be bigger than at Cern: 20 terrabit/sec straight after the A/D converters and still a mighty 0.4 terrabit/sec after the initial data reduction (DSPs + FPGAs). All the remaining data will be transfered over a dedicated fiber network to a central computer. To reduce all this data they need a big fat supercomputer, this will be a IBM Blue Gene with serial number 2, to be handed over tomorrow. For the moment it will be the fastest computer in Europe and ranking somewhere in the top 10 of the world.
So does this mean that - for a change - the record companies themselves are on the receiving end?? (Linked article claims that major record companies are actively 'leaking' new singles onto popular blogs to get positive reviews.)
I believe they will ship the first of these monsters to Livermore to simultate nukes and other deadly stuff. Number 2 will go to the Lofar project. It is basically one huge phased array radio telescope with a diameter of 300 kilometer. Just connect some 10000 simple low frequency (~100 MHz) antennas with big fiber pipes to a central computer and do the beam pointing and imaging all in software.
This is just one reason why governments should pay only for Free Software with taxpayer dollars...
I think this is not really a case to bring up the whole open source debate. The application is probably too specific (a traffic management system for tunnels) that open sourcing it wouldn't have helped society too much (any geek here with a tunnel in his backyard?). It looks much more like a case where the government failed to put proper clauses in the contract from the beginning. If they knew beforehand that a different company would be able to win the contract for the second phase, than the possible transfer of the code should have been in the contract for the first phase. Just a typical contract screw up.
Using Excel for large data sets is a beginners-mistake that a lot of people make, myself inclusive. If you ever want to do some serious number crunching get yourself something decent, like Matlab [or octave(open source but buggy), scylab(free but not open source), IDL...].
I work at Uni and use it for almost all my data analysis, plotting etc. I still see some colleagues (mainly the older ones) selecting columns of 1000 data points in Excel however, while you could do the same with about 5 keystrokes in matlab (a=b+c or s=sum(a)).
It is about time that Europe puts some tough law on software patents in place. Otherwise I fear that VB programmers will emigrate en masse to Europe. Please keep them over there!
They should send three nearly identical copies of the same lander (re-using the same design and development effort), and have them land close enough to communicate directly with each other by radio.
I don't know if that would have saved the mission. The report clearly hints that the failure could have been a design error due to bad management/lack of funding/lack of testing/lack of time. From the TFInquiry: -Air-bag design not robust and the testing programme not sufficient; -Risk of collision between the back cover and the main parachute; -Re-bounding (up to 28mtr) of the air-bag/lander into the main parachute; -Untimely release of the lander from the air-bag. All four involve some luck but could also have been a major design error.
Doubling up the number of landers only helps against failures due to 'statistical bad luck'. If it was a design error (e.g. parachute to small, fatal error in software) nothing would have helped and you would have three craters instead of one. In case of the Mars Exploration Rovers the doubling worked out beautifully: they now have a double chance on getting good science. Similar for the Voyager probes. It is not always beneficial however: sending two orbiters a la Mars Global Surveyor would have lowered the mission risk, but it wouldn't have doubled the science in case of double success (each orbiter sees the whole planet).
Although I think all spammers should be hanged by their balls and it's good to bankrupt them all, I do have some problem with the amount of money that people claim in the American justice system. Next thing you know people will sue because a song contains dirty language.
Slashdot Mirror
As an example take an electrical oscillator that has a frequency that is stable to one part in a million (easy to achieve with a crystal). That means that you can have a length of roughly 1 million wavelengths over which the wave is 'coherent', and thus suitable for interferometry.
direct copy of this comment
BS, current lithography systems are not really limited by the quality of the glass. Limits are mainly caused by the diffraction limit, maybe a little bit by the finite accuracy of polishing and measuring the shapes. And remember that a current lithography machine probably has 500 kilo's of glass in it, so it is not really an option to make that in space.
The infection rate is a nonlinear function (exponential growth and stuff) of user skills, install base, atractivity to malware writers AND inherent security of the OS. People only talk about the last part, while the others might as well explain the differences.
It is always said that there are no viruses on the Mac because it is a better/safer OS. But couldn't this be caused by the type of user alone? I believe there is a very high correlation between buying an Apple and being computer-savvy (or just weird?). Getting infected by a virus usually means some stupid user action (opening an attachment) or not having your patches up to date, both of which are influenced by computer knowledge. This combined with the fact that writers of malware will probably target the biggest install base might be able to explain the different infection rates even with equal number of bugs/level of security. Same story for Linux probably.
Some issues that I could imagine:
-reproducibility: subsequent frames that were rendered by different clients should look exactly the same. This means that only a project provided rendering core can be used, no tinkering allowed by the user.
-copyright (not an issue in this case): suppose Toy Story 7 would use this concept. I guess Disney/Pixar wouldn't be to happy if all the frames were posted online well before the final release. Posting only low-res previews might actually create a big buzz.
What I meant to say was that it is not a sub-category, but clearly a different category (I'm in favour of 1 not of 4). That said, I think the line between them is hard to draw and depends on your perspective (my 'western european democratic kapitalist' vision, that of a palestinian Hamas member or that of the North Korean government).
1: political groups trying to hide from censorship
2: diplomatic/spy-agency messages
3: P2P
4: criminal/terrorist/pedophile activity
I think most people would agree that the great benefit of such a network is number 1. Number 2 is well accepted practice over the last 100 years, so I think there are not much objections against that. Number 3 might be the biggest selling point of this technique, allthough somewhat ethically debatable. I think this problem will be solved in the next 10 years by either the collapse of the content industry or the availibility of better alternatives. That leaves number 4. Is there anything that can be done against that or must this be seen as 'collateral damage'?
So BitTorrent is to blame for this one? Just out of curiosity I looked at Emule and it had roughly 900 sources sharing or downloading. I did not download it (i'm not a SF fan), I just wanted to test my recently installed PeerGuardian, which indeed showed a highly increased activity.
I think I saw a documentary at Discovery Channel about some Russian company that already produces the machines for some years (could be this company). According to the show the traditional diamond industry was so worried that they developed an expensive laser system to discriminate the artificial ones from the natural ones. They could then issue a certificate of 'garanteed blood money' (TM). As a hollywood star/gangsta rapper you of course want to make sure that your hard earned money is well spent on some evil warlord somewhere in Africa.
You got your calculation wrong because you don't get the operating principle of the MERIS instrument. It is not a half megapixel ordinary camera that with some magic collects 15*16 bit per pixel (e.g. by taking 15 images in close succession with a changing filter wheel).
As the page on MERIS says, it is a 'pushbroom imaging spectrometer'. 'Pushbroom' means that instead of a rectangular field of view like a normal camera, it has a line-shaped field of view. An image is formed by continuously observing the single line and wait for the the satellite to 'sweep' the whole planet. 'Imaging spectrograph' means that the previously mentioned line is spectrally separated (with a prism or a grating) perpendicular to the line. You then get an image on your CCD where one direction corresponds to the distance along the line and the other is formed by the different colors.
The optics details of the system are here, an description of the CCD is here. If I understand it correctly, one line is 740 pixels wide and the colors are 'binned' in 15 different spectral bands. That gives you 740*15*2=22200 bytes per line. How much that would be per picture depends on the height of the image, which depends on how long you collect data. In principle you could have it sweep the whole planet non-stop.
I did read the failure investigation report (can be found here, search for polar) some time ago and IIRC the most probable failure scenario was a software error involving a single boolean:
MPL was to land under active control (with rocket power, not the air-bag trick). To kill the moter once it had touched down the legs contained contact sensors which were constructed of a pin with a spring, a magnet and a Hall-sensor. The legs were to be extended some time before touchdown.
The problem was the sensors would trigger some intermediate false readings during the leg extension. These false readings toggled a flag, which, once the control system first started looking for contact, immediately killed the engine, having the lander free-fall to death. Clearing the flag after the leg-extension would have saved the mission. The bug was not found because of errors in the software design documents and lack of a system level test. The intermediate false readings were found in a component level test, but its consequences somehow didn't made it in the final design.
Not that physics is always that understandible: A few weeks ago at a day organized by our national physics society I heard a talk by Frank Wilczek, who won this years prize. He was introduced by 't Hoofd, who won it a few years ago, as being an excelent speaker. I think only a small part of the audience (all physicists) had a clue about what he was talking about, most of my colleagues had to resist falling asleep. I saw a talk by the other guy a year earlier and that was not much better.
Mightbe it is because both men did something in high energy/small partical physics, but I think there are not much nobel prizes that could get the kids to study science. Mightbe x-rays or a MRI scanner, but how do you explain the joy of a Bose-Einstein condensate, a high Tc superconductor or some bloody neutrino?
The data rate might even be bigger than at Cern: 20 terrabit/sec straight after the A/D converters and still a mighty 0.4 terrabit/sec after the initial data reduction (DSPs + FPGAs). All the remaining data will be transfered over a dedicated fiber network to a central computer. To reduce all this data they need a big fat supercomputer, this will be a IBM Blue Gene with serial number 2, to be handed over tomorrow. For the moment it will be the fastest computer in Europe and ranking somewhere in the top 10 of the world.
So does this mean that - for a change - the record companies themselves are on the receiving end?? (Linked article claims that major record companies are actively 'leaking' new singles onto popular blogs to get positive reviews.)
I believe they will ship the first of these monsters to Livermore to simultate nukes and other deadly stuff. Number 2 will go to the Lofar project. It is basically one huge phased array radio telescope with a diameter of 300 kilometer. Just connect some 10000 simple low frequency (~100 MHz) antennas with big fiber pipes to a central computer and do the beam pointing and imaging all in software.
Total device: 6.4 mm length, tip pitch 100 um
/sec
-> 64 rows and 64 columns
-> 4096 tips
Writing speed (from TFwebsite): 'a few microsecond' (say 10)
-> 4096/10e-6 = 410 Mbit
Per tip: range 100 um, bit pitch 10 nm
-> 10000 x 10000 bits = 100 Mbit
Position resolution (really neat device using micro-heaters): 2 nm over 120 um ->
-> 60000 positions observable (probably 16 bit)
I work at Uni and use it for almost all my data analysis, plotting etc. I still see some colleagues (mainly the older ones) selecting columns of 1000 data points in Excel however, while you could do the same with about 5 keystrokes in matlab (a=b+c or s=sum(a)).
It is about time that Europe puts some tough law on software patents in place. Otherwise I fear that VB programmers will emigrate en masse to Europe. Please keep them over there!
-Air-bag design not robust and the testing programme not sufficient;
-Risk of collision between the back cover and the main parachute;
-Re-bounding (up to 28mtr) of the air-bag/lander into the main parachute;
-Untimely release of the lander from the air-bag.
All four involve some luck but could also have been a major design error.
Doubling up the number of landers only helps against failures due to 'statistical bad luck'. If it was a design error (e.g. parachute to small, fatal error in software) nothing would have helped and you would have three craters instead of one. In case of the Mars Exploration Rovers the doubling worked out beautifully: they now have a double chance on getting good science. Similar for the Voyager probes. It is not always beneficial however: sending two orbiters a la Mars Global Surveyor would have lowered the mission risk, but it wouldn't have doubled the science in case of double success (each orbiter sees the whole planet).
Oh wait...
Merry X-mas to all the lawyers.