As an applied physicist wanting a better grasp of the mathematics I use, I'm working through Mathematics of Classical and Quantum Physics by Byron and Fuller. It's a Dover book, so it's inexpensive, and so far it has been enlightening. For instance, it uses the example of vortexes in a swirling bucket of water to help visualize the curl of a vector field.
Well, according to the article, "Once there, astronauts could spend up to 16 months on the Martian surface, and would use nuclear energy to power their habitat." So, at least once they arrive they will be on nuclear power. I don't know why NASA wouldn't want to use NERVAs to go to Mars. Based on a quick google search I did, travel time to Mars would take around 90 days using NERVAs versus 6 months using the "advanced cryogenic fuel propulsion system" cited in the BBC article linked in the summary. Perhaps it would be too difficult to revive a program that has been dead since 1973. But given the radiation concerns NASA has about such a long mission, it seems like it would be worth it to cut travel time in half.
- Joe
To answer your question, you can easily find 1980's Mercedes (or any other) cars that run on diesel for under $5000 and run those on biodiesel. Check your local classifieds. I see two in Houston, TX. Alternatively, you can buy any car whatsoever, adjust the timing, and it will run on ethanol. But you missed the point of my post. I was trying to illuminate the fact that our energy future will not be dependent on any single fuel source. We are much more likely to see a large mix of various technologies, none of which that could solve the energy problem by themselves.
I've never understood why people seem so stuck on whether or not we can completely replace gasoline with some other single fuel source. I'm a graduate student working on my Ph.D., and my thesis is on ways that nanotechnology can be used to harvest energy from the sun. I'm not saying that solar energy is the answer to all the world's problems, my point is only that I've done a lot of research on the energy problem, and from what I've read, there is no reason to expect the world's energy supply to be dominated by a single source in the future. To quote E.H. Lysen and B. Yordi from _Clean Electricity from Photovoltaics_, "... the world's energy supply in the twenty-first century will remain a mix of different energy sources, with a gradually increasing role for renewables, enabling a gradual transition to (ultimately) a fully renewable world energy system." (You can pick up a copy at your local library.)
For example, Ford has a concept truck that can run on gasoline, ethanol, or hydrogen. (Other auto makers also have concepts, no doubt.) Also, considering the fact that most people's daily commute is about 24 minutes (24 miles assuming average speed of 60 mph, which is generous), commutes are well within the range of electric vehicles (if anyone would sell one) or plug-in hybrids. That would allow the energy source for your car to be whatever is on the grid. Which allows wind, solar, bio-mass, nuclear, hydro, etc. to enter the picture. Furthermore, bio-diesel has to be considered as well. So, the long-and-short of it is that while ethanol cannot completely replace gasoline as THE next wonder-fuel, it is entirely feasible for all of our vehicles to be run using renewable energy. Besides, ethanol is produced locally and it reduces our dependence on foreign oil (that's for all those Republicans out there).
Actually, left-handed materials are reality for microwave and terahertz frequencies today. Recent research in plasmonics show possible pathways for creating materials that are left-handed at optical frequencies. For example, see "Nanofabricated media with negative permeability at visible frequencies" by A.N. Grigorenko et al. Vol. 438, pp. 335-338, Nature, 2005. You can pick up a copy at your local library, or read the abstract here. Basically, the advent of nanoscale control of metallic surface features allows us to control the way a surface interacts with incident time-varying electric fields (light). Although at visible frequencies no known material is magnetic, we can engineer the surface in such a way that its electric resonance creates a magnetic response as required by Maxwell's equations.
With 32 bit processors, you need four times the memory to run the same program as an 8 bit CPU. That makes these parts less flexible than their 8 bit counterparts
Not true...32 bit designs can still have memory that is addressable by the byte, and single bytes can still be loaded to or stored from the core registers. You just sign extend the upper 24 bits of the registers (fill with 0 if it's a positive value or 1 if it's negative). So you don't lose any flexibility there.
even though they are a bit faster
Actually, the speed of the processor is only dependent on its clock speed, not the size of the word that it can handle. If your words are 32 bits, then a 32 bit processor is much faster because you don't have the overhead of using 4 registers to hold the word (and manually coding for carries in addition, etc.) So, without a specific model or application in mind, you can't really say anything definitive about speed.
It is shameful because it points to the problem with the US healthcare system as a whole: it is based on capitalism. There shouldn't be a profit motive of any kind when it comes to healthcare if you believe in the premise that "all men are created equal". It introduces inequalities based on economic status.
Don't get me wrong...I don't necessarily trust the government to run the healthcare system (like Canada) either. I think that would result in a hugely inefficient system. But something is clearly wrong with the way things are now.
Re:"you're co-authors of this review."
on
We the Media
·
· Score: 5, Insightful
I think that you are right in that the most important thing about getting news (or any information) is to separate the facts from people's perceptions of things. This is an inherently difficult task because everyone communicates only what they perceive. The great thing about/. in particular is that the moderation system helps to promote opinions or comments that are factual or insightful in some way. Everyone still is responisible for filtering the opinions of others so that they can form their own more informed opinion.
Actually, I would say that all of the technologies mentioned in the article are working in the lab today (the "nanomachines" I'll comment on in a second). I work in the field of nanotechnology, and I can tell you that nanotechnology is just a hype word that means things that are small. You could say that anything a chemist does is "nanotechnology" because molecules are on the nanometer scale. My guess is that the nano-fibers refered to in the article are similar to the electroactive polymers described here.
As for little robotic nanomachines that detect impact and make the armor stiffen, I think those words came from the mouth of a man who probably doesn't really understand the technology in question. The closest things to what I would consider a nanomachine that could possibly be used by 2020 are biological in nature: viruses, proteins, etc. I doubt that is what he really meant to say. Much more likely is that they will develop a new material using nanotechnology that will be some sort of super non-Newtonian fluid. Think silly putty or corn starch mixed with water. These fluids act like solids when they encounter sharp forces, but they act like liquids for slow forces.
I will agree that powering all this equipment will be the limiting factor, but I don't think this is an insurmountable problem. They will probably use a variety of power producing technologies and everything will be interchangable. For example, you could have fuel cells, solar cells, and harness the power created by walking (by compressing some device in the soles of the boots with each step), and you could charge your night vision goggles using whichever power source is available at the time. Different sources would take different lengths of time to charge the goggles depending on the amount of power produced.
Slashdot Mirror
As an applied physicist wanting a better grasp of the mathematics I use, I'm working through Mathematics of Classical and Quantum Physics by Byron and Fuller. It's a Dover book, so it's inexpensive, and so far it has been enlightening. For instance, it uses the example of vortexes in a swirling bucket of water to help visualize the curl of a vector field.
Well, according to the article, "Once there, astronauts could spend up to 16 months on the Martian surface, and would use nuclear energy to power their habitat." So, at least once they arrive they will be on nuclear power. I don't know why NASA wouldn't want to use NERVAs to go to Mars. Based on a quick google search I did, travel time to Mars would take around 90 days using NERVAs versus 6 months using the "advanced cryogenic fuel propulsion system" cited in the BBC article linked in the summary. Perhaps it would be too difficult to revive a program that has been dead since 1973. But given the radiation concerns NASA has about such a long mission, it seems like it would be worth it to cut travel time in half. - Joe
Maybe President Bush can double check...he apparently saved taxpayers millions by catching an error in some calculations over at Fermi labs.
Interesting point...do you happen to know what the change in volume of gasoline is for changes in temperature from 0 to 40 C?
To answer your question, you can easily find 1980's Mercedes (or any other) cars that run on diesel for under $5000 and run those on biodiesel. Check your local classifieds. I see two in Houston, TX. Alternatively, you can buy any car whatsoever, adjust the timing, and it will run on ethanol. But you missed the point of my post. I was trying to illuminate the fact that our energy future will not be dependent on any single fuel source. We are much more likely to see a large mix of various technologies, none of which that could solve the energy problem by themselves.
For example, Ford has a concept truck that can run on gasoline, ethanol, or hydrogen. (Other auto makers also have concepts, no doubt.) Also, considering the fact that most people's daily commute is about 24 minutes (24 miles assuming average speed of 60 mph, which is generous), commutes are well within the range of electric vehicles (if anyone would sell one) or plug-in hybrids. That would allow the energy source for your car to be whatever is on the grid. Which allows wind, solar, bio-mass, nuclear, hydro, etc. to enter the picture. Furthermore, bio-diesel has to be considered as well. So, the long-and-short of it is that while ethanol cannot completely replace gasoline as THE next wonder-fuel, it is entirely feasible for all of our vehicles to be run using renewable energy. Besides, ethanol is produced locally and it reduces our dependence on foreign oil (that's for all those Republicans out there).
None of these materials have much of a bandwidth, as the article mentions.
True...
Actually, left-handed materials are reality for microwave and terahertz frequencies today. Recent research in plasmonics show possible pathways for creating materials that are left-handed at optical frequencies. For example, see "Nanofabricated media with negative permeability at visible frequencies" by A.N. Grigorenko et al. Vol. 438, pp. 335-338, Nature, 2005. You can pick up a copy at your local library, or read the abstract here. Basically, the advent of nanoscale control of metallic surface features allows us to control the way a surface interacts with incident time-varying electric fields (light). Although at visible frequencies no known material is magnetic, we can engineer the surface in such a way that its electric resonance creates a magnetic response as required by Maxwell's equations.
I've also seen people who look like they go to the gym 5 times a week even though they hardly work out at all. Thats genetics.
...or steroids
Not true...32 bit designs can still have memory that is addressable by the byte, and single bytes can still be loaded to or stored from the core registers. You just sign extend the upper 24 bits of the registers (fill with 0 if it's a positive value or 1 if it's negative). So you don't lose any flexibility there.
Actually, the speed of the processor is only dependent on its clock speed, not the size of the word that it can handle. If your words are 32 bits, then a 32 bit processor is much faster because you don't have the overhead of using 4 registers to hold the word (and manually coding for carries in addition, etc.) So, without a specific model or application in mind, you can't really say anything definitive about speed.
Don't get me wrong...I don't necessarily trust the government to run the healthcare system (like Canada) either. I think that would result in a hugely inefficient system. But something is clearly wrong with the way things are now.
I think that you are right in that the most important thing about getting news (or any information) is to separate the facts from people's perceptions of things. This is an inherently difficult task because everyone communicates only what they perceive. The great thing about /. in particular is that the moderation system helps to promote opinions or comments that are factual or insightful in some way. Everyone still is responisible for filtering the opinions of others so that they can form their own more informed opinion.
Actually, I would say that all of the technologies mentioned in the article are working in the lab today (the "nanomachines" I'll comment on in a second). I work in the field of nanotechnology, and I can tell you that nanotechnology is just a hype word that means things that are small. You could say that anything a chemist does is "nanotechnology" because molecules are on the nanometer scale. My guess is that the nano-fibers refered to in the article are similar to the electroactive polymers described here. As for little robotic nanomachines that detect impact and make the armor stiffen, I think those words came from the mouth of a man who probably doesn't really understand the technology in question. The closest things to what I would consider a nanomachine that could possibly be used by 2020 are biological in nature: viruses, proteins, etc. I doubt that is what he really meant to say. Much more likely is that they will develop a new material using nanotechnology that will be some sort of super non-Newtonian fluid. Think silly putty or corn starch mixed with water. These fluids act like solids when they encounter sharp forces, but they act like liquids for slow forces. I will agree that powering all this equipment will be the limiting factor, but I don't think this is an insurmountable problem. They will probably use a variety of power producing technologies and everything will be interchangable. For example, you could have fuel cells, solar cells, and harness the power created by walking (by compressing some device in the soles of the boots with each step), and you could charge your night vision goggles using whichever power source is available at the time. Different sources would take different lengths of time to charge the goggles depending on the amount of power produced.