I once had a chat with a NASA biomedical researcher who told me that astronauts in space occasionally see flashes of light. These flashes coincide with cosmic rays destroying cones and/or rods in their retina. Not a pleasant thought if you ask me.
Of course, these same cosmic rays will also destroy cells in the brain and fragment DNA, potentially generating damage which could either lead to cancer or lead to genetic problems which could be passed on to future generations.
Although I can't quantify the risk associated with the latter phenomena, knowing that every time I see a little flash I have suffered a small but permanent loss of vision would make space travel less appealing.
I've noticed a fair amount of the people are mom-and-pop types who have zero computer experience. These are the same types who at one point will figure out you can resize a browser window by clicking and dragging a corner and think they've discovered the greatest thing since sliced bread.
Let's see, we need a place where people speak English, there is a significant number of people who know something about computers, and the wages are even lower than in India.
Given the plethora of 419 e-mails that evade my spam filter, how about Nigeria?
I knew the space elevator advocates would come out when this was posted. Let's consider the space elevator from a green and practical standpoint:
1.) We know of no method to make the multi-kilometer long nanotubes necessary for the space elevator. We are not even close--we need a multi-order of magnitude breakthrough to make this happen.
2.) We just aren't looking for microgram lab quantities here. We would need to scale the synthesis of these mega-nanotubes to industrial levels to generate the thousands of tons of material necessary for the space elevator. This represents another multi-order of magnitude breakthrough necessary to even contiplate a space elevator.
3.) How the hell do we know that industrial prodution of mega-nanotubes will be environmentally friendly?
4.) You can't build the space elevator from the Earth up. You have to start at geosynchronous orbit. This means that we will need conventional rockets to move the entire mass of the elevator into orbit. Furthermore, we will need to bring up the life support to and necessary infrastructure for the workers building the thing. In other words, we need a conventional green launch platform before we can build an envionmentally green elevator.
The super-long nanotubes are the enabling technology for the space elevator. Of course, if we develop something this handy, there will be many applications for these materials before the technology is sufficiently advanced for the space elevator. When we see super-long nanotube composites used in aircraft hulls, rocket engines, tennis rackets, sports cars, laptop cases, etc., we will have a technology base that's sufficiently advanced to realistically contemplate the space elevator.
Furthermore, if it's feasible to develop this ultra-long nanotube technology, the existing market for advanced composites will ensure that it is developed. We don't need our underfunded space agency wasting any of its dollars on this concept until the mega-nanotube technology is anything more than science fiction.
When their print heads get so hopelessly clogged that you can't clean them any more, you need to chuck the printer and get a new one. It's a damn shame, too, since they make the best ink in the business.
Ok, I see your point. People will adjust the volume (and therefore the output voltage level) for a particular audio power output from the speakers.
Having said that, what really matters is the efficiency at which the speaker converts electrical power to audio power. It's not obvious to me if speaker efficiency depends on speaker impedance. (There are other issues to worry about if you make big changes in speaker impedance, such the maximum current and voltage that the electronics can provide, but let's not worry about that for now.) Therefore, we can postulate that a brand x ear-bud (or headphone) might not be as efficient as an Apple ear-bud for some undetermined reason.
Another possibility could be that the i-pod is plugged into a completly different device (such as an air-tunes transmitter or powered loudspeakers). In such a case, the power requirements could differ significantly from the air-buds and all bets are off.
Mod this guy up! He has it right. It drives me nuts that/.ers know so little about science and technology when push comes to shove. This stuff is introductory electronics, folks. I can see that a few posters might get it wrong but what about the moderators?
As I understand it, the advantage for liquid metal cooling in nuclear reactors is the high operating temperature. For an ideal Carnot heat engine, a larger deltaT leads to a more efficient engine.
In the case of a processor, I don't see any clear advantage. As far as room temperature liquid coolants are concerned, water is hard to beat because it has an unusually high heat capacity.
These mixers require cryogenic cooling, and we're talking liquid helium here--liquid nitrogen doesn't cut it. They're great for astronomers looking for the lowest noise possible, but I don't think we will be seeing any on e-Bay any time soon.
The way to do it is heterodyne detection. In order to do this you need a mixer and a local oscillator. You can purchases special Schottky diode mixers that are engineered for this application.
Your local oscillator can be an off the shelf line-tunable Far-IR laser. These lasers are based on rotational transitions in small molecules in the gas phase. These lasers are pumped with a CO2 laser. If the conditions are right, the dynamics of vibrational to rotational energy transfer give you a population inversion. These lasers make nice local oscillators because they have been used for years for sub-mm wave astronomy and the frequencies of their lines are known to a large number of significant figures.
Once you have a local oscillator and a mixer, you can measure the beat frequency with an off-the-shelf spectrum analyzer.
This is not an issue because we are far from the quantum limit here. You are correct that the plasmons are quantized. The RF energy that travels through the interconnects on conventional chips is also quantized. Nobody talks about this because it is a non-issue. Even even when you scale things up by 10^4, it's a non issue. You can just use 10^4 times fewer quanta to deliver your signals and the power can stay the same.
I am also a scientist. Much of the work that I do is contract research for the government. Most agencies that I have encountered require regular reports in MS Word format. This requirement is typically incorporated into the language of the contract. The primary problem with MS Word on the Mac is their horrid rendering of emf graphics, and their refusal to provide WYSIWYG eps graphics on either platform. This effectively means that there is no good cross-platform answer for vector graphics if I am forced by my customer to work in Word.
Fortunately, they don't dictate how I analyze my data. My preferred data analysis & plotting package is Igor Pro, and it works really well in OS X.
I never said that all devices that require a coherent pump are not lasers. However, there are significant differences between oscillators based on non-linear phenomena and the oscillators that you list that are based on stimulated emission.
The other point is that if any laser pumped oscillator is the basis of an integrated optical device, there are some potential efficiency problems unless the device is damn efficient. Furthermore, there is always the expense and bulk of a separate pump laser.
Laser: Light Amplification by Stimulated Emission of Radiation.
The stimulated Raman effect is fundamentally different from stimulated emission. You can't get stimulated emission from Si because it is an indirect bandgap semiconductor. However, it is true that both processes can generate coherent beams of light, and people typically refer to devices that generate coherent light as laser sources, hence the term "Raman Laser".
However, my point is that this device can't convert non-optical energy into optical energy. Furthermore, since it's a non-linear optical process, you can only get the necessary intinsity to drive this process from a coherent source. Therefore you must have an actual laser to start this process. This is something that they state in the articles. However, in the c/net article, the marketing hype starts to take over. They state, "The Santa Clara, Calif.-based company has created a chip containing eight continuous Raman lasers by using fairly standard silicon processes rather than the somewhat expensive materials and processes required for making lasers today." Implying that this gets us away needing old-fashoned expensive lasers. It doesn't.
Yes, they are nice, small coherent light sources that can be easily modulated and integrated into Si, but they aren't lasers, and the efficiency is a problem.
Let's say you want to start making integrated optical circuits. If you want a chip with 100 switches, you must pump each switch with 300 mW. (Well maybe you could cut back to 100 mW, but the efficiency of these things is non-linear, and there will be a threshold power at which they don't work.) Therefore, a device with just 100 switches would require 10 to 30 watts of coherent optical power to drive it. Then you need to worry about the wall-plug efficiency of your pump laser (or lasers) and the bulk of the pump laser.
It's interesting, and it did deserve an article in Nature. However, there's a lot of corporate marketing hype behind all the buzz in the linked articles, and when marketing hype and science mix I get annoyed.
It's based on Raman shifting. It's a nice way of getting longer wavelength light from shorter wavelength light, but you still need a pricey(non-silicon) laser to make it work. Furthermore, because the Raman process has limited efficiency, you end up loosing much of the efficiency of a conventional (non-silicon) diode laser.
It's only interesting because it can be electronically swiched on and off, so it represents a nice way of getting modulated light into a silicon waveguide. On the other hand, there are modulators with much better efficiency. So it's a cheap but inefficient modulator, which is also a wavelength converter.
Less stuff to schlep around. If one gadget can function as an i-Pod, cell phone, PDA, and digital camera, that's less to carry.
Of course, to be truly useful, it must do all the functions well. I personally don't see the point of the camera-phone combo, but that's mainly because they aren't especially good cameras, and I don't need a camera with me all the time anyhow.
Slashdot Mirror
It's not quite lunch, it's not quite supper; let's call it lupper!
Most women make me pay for using their pipes!
I once had a chat with a NASA biomedical researcher who told me that astronauts in space occasionally see flashes of light. These flashes coincide with cosmic rays destroying cones and/or rods in their retina. Not a pleasant thought if you ask me.
Of course, these same cosmic rays will also destroy cells in the brain and fragment DNA, potentially generating damage which could either lead to cancer or lead to genetic problems which could be passed on to future generations.
Although I can't quantify the risk associated with the latter phenomena, knowing that every time I see a little flash I have suffered a small but permanent loss of vision would make space travel less appealing.
Let's see, we need a place where people speak English, there is a significant number of people who know something about computers, and the wages are even lower than in India.
Given the plethora of 419 e-mails that evade my spam filter, how about Nigeria?
Actually, given the rural pollution problems from chicken and pig lots, a rocket that would burn shit would be a welcomed innovation.
I knew the space elevator advocates would come out when this was posted. Let's consider the space elevator from a green and practical standpoint:
1.) We know of no method to make the multi-kilometer long nanotubes necessary for the space elevator. We are not even close--we need a multi-order of magnitude breakthrough to make this happen.
2.) We just aren't looking for microgram lab quantities here. We would need to scale the synthesis of these mega-nanotubes to industrial levels to generate the thousands of tons of material necessary for the space elevator. This represents another multi-order of magnitude breakthrough necessary to even contiplate a space elevator.
3.) How the hell do we know that industrial prodution of mega-nanotubes will be environmentally friendly?
4.) You can't build the space elevator from the Earth up. You have to start at geosynchronous orbit. This means that we will need conventional rockets to move the entire mass of the elevator into orbit. Furthermore, we will need to bring up the life support to and necessary infrastructure for the workers building the thing. In other words, we need a conventional green launch platform before we can build an envionmentally green elevator.
The super-long nanotubes are the enabling technology for the space elevator. Of course, if we develop something this handy, there will be many applications for these materials before the technology is sufficiently advanced for the space elevator. When we see super-long nanotube composites used in aircraft hulls, rocket engines, tennis rackets, sports cars, laptop cases, etc., we will have a technology base that's sufficiently advanced to realistically contemplate the space elevator.
Furthermore, if it's feasible to develop this ultra-long nanotube technology, the existing market for advanced composites will ensure that it is developed. We don't need our underfunded space agency wasting any of its dollars on this concept until the mega-nanotube technology is anything more than science fiction.
When their print heads get so hopelessly clogged that you can't clean them any more, you need to chuck the printer and get a new one. It's a damn shame, too, since they make the best ink in the business.
This looks useful. I just might take it for a spin. However, it appears that it hasn't been updated for a year. It might be getting a bit out of date.
Does Richard Simmons know about this?
Ok, I see your point. People will adjust the volume (and therefore the output voltage level) for a particular audio power output from the speakers.
Having said that, what really matters is the efficiency at which the speaker converts electrical power to audio power. It's not obvious to me if speaker efficiency depends on speaker impedance. (There are other issues to worry about if you make big changes in speaker impedance, such the maximum current and voltage that the electronics can provide, but let's not worry about that for now.) Therefore, we can postulate that a brand x ear-bud (or headphone) might not be as efficient as an Apple ear-bud for some undetermined reason.
Another possibility could be that the i-pod is plugged into a completly different device (such as an air-tunes transmitter or powered loudspeakers). In such a case, the power requirements could differ significantly from the air-buds and all bets are off.
Mod this guy up! He has it right. It drives me nuts that /.ers know so little about science and technology when push comes to shove. This stuff is introductory electronics, folks. I can see that a few posters might get it wrong but what about the moderators?
As I understand it, the advantage for liquid metal cooling in nuclear reactors is the high operating temperature. For an ideal Carnot heat engine, a larger deltaT leads to a more efficient engine.
In the case of a processor, I don't see any clear advantage. As far as room temperature liquid coolants are concerned, water is hard to beat because it has an unusually high heat capacity.
just defrag it
These mixers require cryogenic cooling, and we're talking liquid helium here--liquid nitrogen doesn't cut it. They're great for astronomers looking for the lowest noise possible, but I don't think we will be seeing any on e-Bay any time soon.
This is done all the time in sub-mm astronomy.
The way to do it is heterodyne detection. In order to do this you need a mixer and a local oscillator. You can purchases special Schottky diode mixers that are engineered for this application.
Your local oscillator can be an off the shelf line-tunable Far-IR laser. These lasers are based on rotational transitions in small molecules in the gas phase. These lasers are pumped with a CO2 laser. If the conditions are right, the dynamics of vibrational to rotational energy transfer give you a population inversion. These lasers make nice local oscillators because they have been used for years for sub-mm wave astronomy and the frequencies of their lines are known to a large number of significant figures.
Once you have a local oscillator and a mixer, you can measure the beat frequency with an off-the-shelf spectrum analyzer.
This is not an issue because we are far from the quantum limit here. You are correct that the plasmons are quantized. The RF energy that travels through the interconnects on conventional chips is also quantized. Nobody talks about this because it is a non-issue. Even even when you scale things up by 10^4, it's a non issue. You can just use 10^4 times fewer quanta to deliver your signals and the power can stay the same.
In the event of an epidemic, this would be a good thing. Does this mean that if epidemics select for antisocial nerds, /.'ers will rule the earth?
Well...If it had Scooby Doo and his gang or the X-Men painted on the side, I would be excited.
Fortunately, they don't dictate how I analyze my data. My preferred data analysis & plotting package is Igor Pro, and it works really well in OS X.
Well, there's always the possibility for a class action lawsuit that would really make them feel some pain...
Oh, what's that? Not anymore? I guess everyone in their database is just screwed.
God Bless America!
The other point is that if any laser pumped oscillator is the basis of an integrated optical device, there are some potential efficiency problems unless the device is damn efficient. Furthermore, there is always the expense and bulk of a separate pump laser.
Try learning physics.
Laser: Light Amplification by Stimulated Emission of Radiation.
The stimulated Raman effect is fundamentally different from stimulated emission. You can't get stimulated emission from Si because it is an indirect bandgap semiconductor. However, it is true that both processes can generate coherent beams of light, and people typically refer to devices that generate coherent light as laser sources, hence the term "Raman Laser".
However, my point is that this device can't convert non-optical energy into optical energy. Furthermore, since it's a non-linear optical process, you can only get the necessary intinsity to drive this process from a coherent source. Therefore you must have an actual laser to start this process. This is something that they state in the articles. However, in the c/net article, the marketing hype starts to take over. They state, "The Santa Clara, Calif.-based company has created a chip containing eight continuous Raman lasers by using fairly standard silicon processes rather than the somewhat expensive materials and processes required for making lasers today." Implying that this gets us away needing old-fashoned expensive lasers. It doesn't.
Yes, they are nice, small coherent light sources that can be easily modulated and integrated into Si, but they aren't lasers, and the efficiency is a problem.
Let's say you want to start making integrated optical circuits. If you want a chip with 100 switches, you must pump each switch with 300 mW. (Well maybe you could cut back to 100 mW, but the efficiency of these things is non-linear, and there will be a threshold power at which they don't work.) Therefore, a device with just 100 switches would require 10 to 30 watts of coherent optical power to drive it. Then you need to worry about the wall-plug efficiency of your pump laser (or lasers) and the bulk of the pump laser.
It's interesting, and it did deserve an article in Nature. However, there's a lot of corporate marketing hype behind all the buzz in the linked articles, and when marketing hype and science mix I get annoyed.
It's based on Raman shifting. It's a nice way of getting longer wavelength light from shorter wavelength light, but you still need a pricey(non-silicon) laser to make it work. Furthermore, because the Raman process has limited efficiency, you end up loosing much of the efficiency of a conventional (non-silicon) diode laser.
It's only interesting because it can be electronically swiched on and off, so it represents a nice way of getting modulated light into a silicon waveguide. On the other hand, there are modulators with much better efficiency. So it's a cheap but inefficient modulator, which is also a wavelength converter.
Less stuff to schlep around. If one gadget can function as an i-Pod, cell phone, PDA, and digital camera, that's less to carry.
Of course, to be truly useful, it must do all the functions well. I personally don't see the point of the camera-phone combo, but that's mainly because they aren't especially good cameras, and I don't need a camera with me all the time anyhow.