I think comparing prices is probably fair in this situation - certainly if gas costs more than electricity that should tell you that there is something wrong with your model. Here are some possibilities: evil conspiracy (just getting it out of the way); the gas needs to be prepared much more carefully for domestic use than industrial - bad smells need to be removed, monoxide and h2s need to be removed; the gas needs to be pumped around a huge distribution system with friction and leakage losses; gas wires are more expensive to lay, join and prepare than electricity wires. Electricity can also do something else before being turned to heat (such as computing) which makes it more 'efficient'. Gas is more expensive than coal (takes more energy to dig up than coal).
Also note that except in the case of greenhouses, the exhaust gas is unwanted and must be vented outside, which has a significant energy loss incurred. Electrical heaters can be far more focussed - an electric blanket is far more efficient than a gas central heating unit.
There's a probably a bunch of other energy costs associated with gas that aren't associated with electricity, finding them out is left as an exercise for the reader.
"and is equal to the cosine of the difference between the current phase and voltage phase. "
Actually, this is only true for linear devices (resistors, inductors and capacitors). Everything else introduces harmonics which also affect the power factor. Cheap switch mode power supplies, such as in your computer, produces really nasty harmonics as they steal only from the leading edge of the tops of the wave. Light dimmers produce similar nasty waveforms.
A true energy meter such as the Kill-A-Watt will correctly measure this instantaneous power and integrate it up in a convenient form.
"(important for the spouse when the bulb is exposed)"
Interesting, my wife actually likes the look of the twisted tubes and picks out the shapes she likes. Perhaps you are just approaching the problem in the wrong way?;)
Interesting. In my experience, which is based on publications and people I meet at conferences, American (US) PhDs are weaker than European (including UK and former USSR), Japanese or Australian/New Zealand PhDs. I think the US system has been resting on its laurels for a tad long. The best American researchers tend to be those born and trained elsewhere as well. I think the US education system is so broken that it's a wonder that anybody gets through still capable of rational thought.
Actually, there are plenty of hot springs in the desert. The outflow rates are not high and the temperature is usually around 50C, so it is not practical for large scale geothermal. Look up Dalhousie Hot Springs.
I can pick up a 100A 100V MOSFET for a dollar. three-stage isolation is probably trivial to implement at these voltages and currents. Otherwise I agree with you.
stepping from 12 down to 5V (more likely something like 48V to 5V) is much easier than stepping down from 90-260V AC with proper isolation. A low voltage DC -> DC converter can use simple topologies like buck and buck/boost with much smaller inductors and capacitors (as the inductor stores less than half the power). Buck regulators are easy to make more than 90% efficient, compared to flyback ones getting 80% in conventional power supplies.
I have a 5kW 95% battery charger which cost me just over $1000, a 500W 95% power supply costs more than $100.
So perhaps google needs to start undermining Microsoft's core business (OS and Office). A good way to do this might be to offer money to free software developers to improve the competition (SoC). Another way would be for google to support free software with more than lip service - contribute back patches, and employ people to work on free software (code.google.com ?). Finally, they could show support for linux with their official offerings, such as google earth.
They certainly have started down this path, but perhaps they need to be a little more pro-active, particularly on the last point.
>> Does time dilation prevent the singularity from ever forming?
> I think a more interesting question is whether an event horizon can form in finite time in a distant observer's frame, and no one has ever given me a straight answer.
Yes, I think that this is one of my big puzzles. Thanks for stating it far more clearly than I could (and thanks for your answers, it's so much nicer to hear thought than the usual self-assured drivel). I did general relativity years ago and it's all gone vague on me (I probably never really understood it:), I did indeed mean Schwartzchild radius, rather than Chandrasekhar limit. The problems I had with black holes are:
1) how do you confine mass enough in finite time. (Consider dropping bricks into a star till it turns into a blackhole, the last brick may never make it!)
2) the background radiation forms a brilliantly heated horizon that will act to reduce incoming mass more.
There were 6 more reasons that other smarter people have pointed out when I've talked about this in the past, but I can't remember them now.
Or maybe they can't see anything because all light coming off it is so redshifted it can't be distinguished from the background. Or maybe the surface is just painted matt black. You make a leap from dense matter to singularity which I was questioning.
It doesn't show that there is a singularity though; only that there is a lot of mass in that region. It could equally be a new super dense form of matter that we don't yet understand. Their claim that if it were a super dense form of matter then it must turn into a black hole sounds like wishful thinking to me.
For you astrophysics geeks out there, how does a black hole actually form from a super dense lump of mass? Chandra's limit is all very nice, but I've never heard a compelling explanation as to how matter would be helped across this point? Does the blackhole form in the very middle and expand outwards, or does the whole star just disappear? If it forms in the middle, why don't protons turn into blackholes from the middle out? Does time dilation prevent the singularity from ever forming? What about the photon pressure from the 4K background preventing further accretion (which would become a seeringly hot light near the singularity)?
Exactly, and this is what makes this a great new idea - self repairing sensors are better than super robust ones in practice. If you choose the right organisms they get a nice home and you get a useful measure, it's pretty much how life works isn't it:)
But they had bronze and silver. Having a double sided mirror makes it much easier to aim too, so I suggest that they more likely just used large sheets of metal (perhaps with a hole in the middle for aiming).
Actually, measuring humidity accurately for a reasonable period of time is very difficult - things tend to corrode, gum up, rot or wear out. I can buy a 0.1C temp sensor for 50 cents, a 1% humidity sensor costs $50 and in my test environment (a greenhouse) lasts about 2 years.
Why do people get so hung up about efficiency? Efficiency is only relevant to generation if you pay for the fuel, otherwise $/W is a far more useful measure. An electric heater is 100% efficient, but it's a poor way to heat a house. For stationary energy production covering everything with 5% panels costing $2/W is a much better solution than forking out for $50/W 25% panels.
Regarding density, my parents meet their unrestrained electrical demands using solar power from just the north side of their modest sized roof. If every house did this then the remainder of the demand could easily be met by existing plants.
As for cheap energy, we already have cheap energy. I can go down to the shop and buy a gigajoule of energy for the cost of a meal. The amount of research has actually gone down with reducing prices of energy, so I doubt there is a significant cause there.
That is not true. LEDs make excellent task lighting and nightlight (I have little solar power garden lights that look good and make navigation easier). A 15W LED is currently impractical - I have tried Luxeons, arrays and that new korean brand and none are as good as a compact fluoro. (let alone as cheap!) The 150W equivalent compact fluoro I'm referring to is only 22W.
I also have LEDs mounted in the ceiling drilling through the plaster using red, powered by a trickle charged gel cel. This gives me night light in a power failure for only a few dollars outlay. LEDs are very reliable and don't need 240V inverter power to run (I actually made a simple constant current buck-boost driver for the led string though, which is beyond most people).
So you can see I've done the LED thing, and believe me, they aren't a good white light source yet.
I bought some warm white leds for replacing grain-of-wheats in a vintage radio indicator. A white led is usually just a blue led with a yellow fluorescent coat. By using more or less yellow you can get any temp from about 2000K up to 10000k. The problem with LEDs as lights is their high cost per watt, nothing else. I can pick up a compact fluoro for a few dollars and get 150W incandescent equivalent. No LED comes close to that.
Most people prefer high temperatures for internal lighting - look at the use of halogen downlights and more recently, HID spots in shops. Low temps are used mainly for mood or cultural reference (ye olde).
I probably shouldn't reply, but in answer to "WtF is bothering you?": I've just been kicked out of our house without warning, and am now fighting real-estate agents, I have to give a conference talk on the other side of the world in a week's time and I need to submit my PhD by the end of the year. So the reality is that I'm too stressed and as a result say stupid things. I think I should stop reading slashdot, but the escapism has been useful.
Slashdot Mirror
They don't use ball bearings in HDDs any more, they use foil or fluid bearings.
I think comparing prices is probably fair in this situation - certainly if gas costs more than electricity that should tell you that there is something wrong with your model. Here are some possibilities: evil conspiracy (just getting it out of the way); the gas needs to be prepared much more carefully for domestic use than industrial - bad smells need to be removed, monoxide and h2s need to be removed; the gas needs to be pumped around a huge distribution system with friction and leakage losses; gas wires are more expensive to lay, join and prepare than electricity wires. Electricity can also do something else before being turned to heat (such as computing) which makes it more 'efficient'. Gas is more expensive than coal (takes more energy to dig up than coal).
Also note that except in the case of greenhouses, the exhaust gas is unwanted and must be vented outside, which has a significant energy loss incurred. Electrical heaters can be far more focussed - an electric blanket is far more efficient than a gas central heating unit.
There's a probably a bunch of other energy costs associated with gas that aren't associated with electricity, finding them out is left as an exercise for the reader.
Actually, this is the state of power distribution everywhere but the US colonies :)
"and is equal to the cosine of the difference between the current phase and voltage phase. "
Actually, this is only true for linear devices (resistors, inductors and capacitors). Everything else introduces harmonics which also affect the power factor. Cheap switch mode power supplies, such as in your computer, produces really nasty harmonics as they steal only from the leading edge of the tops of the wave. Light dimmers produce similar nasty waveforms.
A true energy meter such as the Kill-A-Watt will correctly measure this instantaneous power and integrate it up in a convenient form.
"(important for the spouse when the bulb is exposed)"
;)
Interesting, my wife actually likes the look of the twisted tubes and picks out the shapes she likes. Perhaps you are just approaching the problem in the wrong way?
I never claimed anything about standards, just about results. Fully US educated researchers seem to me to be weaker than those educated elsewhere.
Interesting. In my experience, which is based on publications and people I meet at conferences, American (US) PhDs are weaker than European (including UK and former USSR), Japanese or Australian/New Zealand PhDs. I think the US system has been resting on its laurels for a tad long. The best American researchers tend to be those born and trained elsewhere as well. I think the US education system is so broken that it's a wonder that anybody gets through still capable of rational thought.
Actually, there are plenty of hot springs in the desert. The outflow rates are not high and the temperature is usually around 50C, so it is not practical for large scale geothermal. Look up Dalhousie Hot Springs.
Here's an example where SI units clean up over imperial. If you work out the same problem in L/100km it is trivial. MPG is a silly unit.
I can pick up a 100A 100V MOSFET for a dollar. three-stage isolation is probably trivial to implement at these voltages and currents. Otherwise I agree with you.
stepping from 12 down to 5V (more likely something like 48V to 5V) is much easier than stepping down from 90-260V AC with proper isolation. A low voltage DC -> DC converter can use simple topologies like buck and buck/boost with much smaller inductors and capacitors (as the inductor stores less than half the power). Buck regulators are easy to make more than 90% efficient, compared to flyback ones getting 80% in conventional power supplies.
I have a 5kW 95% battery charger which cost me just over $1000, a 500W 95% power supply costs more than $100.
So perhaps google needs to start undermining Microsoft's core business (OS and Office). A good way to do this might be to offer money to free software developers to improve the competition (SoC). Another way would be for google to support free software with more than lip service - contribute back patches, and employ people to work on free software (code.google.com ?). Finally, they could show support for linux with their official offerings, such as google earth.
They certainly have started down this path, but perhaps they need to be a little more pro-active, particularly on the last point.
>> Does time dilation prevent the singularity from ever forming?
:), I did indeed mean Schwartzchild radius, rather than Chandrasekhar limit. The problems I had with black holes are:
> I think a more interesting question is whether an event horizon can form in finite time in a distant observer's frame, and no one has ever given me a straight answer.
Yes, I think that this is one of my big puzzles. Thanks for stating it far more clearly than I could (and thanks for your answers, it's so much nicer to hear thought than the usual self-assured drivel). I did general relativity years ago and it's all gone vague on me (I probably never really understood it
1) how do you confine mass enough in finite time. (Consider dropping bricks into a star till it turns into a blackhole, the last brick may never make it!)
2) the background radiation forms a brilliantly heated horizon that will act to reduce incoming mass more.
There were 6 more reasons that other smarter people have pointed out when I've talked about this in the past, but I can't remember them now.
"The biggest problem seems to be that the energy source available seems to be the light energy from a couple hundred watt lamp."
From TFA: 'an industrial searchlight'
I read this to mean one of those 10000W carbon arc searchlights they use to spot planes and highlight new shopping centres, like this: http://www.geocities.com/bobz299/searchlight3.htm
What evidence is there that light cannot escape? How do you know it isn't just a very dim, dense star?
Or maybe they can't see anything because all light coming off it is so redshifted it can't be distinguished from the background. Or maybe the surface is just painted matt black. You make a leap from dense matter to singularity which I was questioning.
It doesn't show that there is a singularity though; only that there is a lot of mass in that region. It could equally be a new super dense form of matter that we don't yet understand. Their claim that if it were a super dense form of matter then it must turn into a black hole sounds like wishful thinking to me.
For you astrophysics geeks out there, how does a black hole actually form from a super dense lump of mass? Chandra's limit is all very nice, but I've never heard a compelling explanation as to how matter would be helped across this point? Does the blackhole form in the very middle and expand outwards, or does the whole star just disappear? If it forms in the middle, why don't protons turn into blackholes from the middle out? Does time dilation prevent the singularity from ever forming? What about the photon pressure from the 4K background preventing further accretion (which would become a seeringly hot light near the singularity)?
Exactly, and this is what makes this a great new idea - self repairing sensors are better than super robust ones in practice. If you choose the right organisms they get a nice home and you get a useful measure, it's pretty much how life works isn't it :)
But they had bronze and silver. Having a double sided mirror makes it much easier to aim too, so I suggest that they more likely just used large sheets of metal (perhaps with a hole in the middle for aiming).
Actually, measuring humidity accurately for a reasonable period of time is very difficult - things tend to corrode, gum up, rot or wear out. I can buy a 0.1C temp sensor for 50 cents, a 1% humidity sensor costs $50 and in my test environment (a greenhouse) lasts about 2 years.
Why do people get so hung up about efficiency? Efficiency is only relevant to generation if you pay for the fuel, otherwise $/W is a far more useful measure. An electric heater is 100% efficient, but it's a poor way to heat a house. For stationary energy production covering everything with 5% panels costing $2/W is a much better solution than forking out for $50/W 25% panels.
Regarding density, my parents meet their unrestrained electrical demands using solar power from just the north side of their modest sized roof. If every house did this then the remainder of the demand could easily be met by existing plants.
As for cheap energy, we already have cheap energy. I can go down to the shop and buy a gigajoule of energy for the cost of a meal. The amount of research has actually gone down with reducing prices of energy, so I doubt there is a significant cause there.
That is not true. LEDs make excellent task lighting and nightlight (I have little solar power garden lights that look good and make navigation easier). A 15W LED is currently impractical - I have tried Luxeons, arrays and that new korean brand and none are as good as a compact fluoro. (let alone as cheap!) The 150W equivalent compact fluoro I'm referring to is only 22W.
I also have LEDs mounted in the ceiling drilling through the plaster using red, powered by a trickle charged gel cel. This gives me night light in a power failure for only a few dollars outlay. LEDs are very reliable and don't need 240V inverter power to run (I actually made a simple constant current buck-boost driver for the led string though, which is beyond most people).
So you can see I've done the LED thing, and believe me, they aren't a good white light source yet.
I bought some warm white leds for replacing grain-of-wheats in a vintage radio indicator. A white led is usually just a blue led with a yellow fluorescent coat. By using more or less yellow you can get any temp from about 2000K up to 10000k. The problem with LEDs as lights is their high cost per watt, nothing else. I can pick up a compact fluoro for a few dollars and get 150W incandescent equivalent. No LED comes close to that.
Most people prefer high temperatures for internal lighting - look at the use of halogen downlights and more recently, HID spots in shops. Low temps are used mainly for mood or cultural reference (ye olde).
Absolutely! We need to be building a pirate power supply out of alternative energy sources, perhaps with downloadable construction plans.
I probably shouldn't reply, but in answer to "WtF is bothering you?": I've just been kicked out of our house without warning, and am now fighting real-estate agents, I have to give a conference talk on the other side of the world in a week's time and I need to submit my PhD by the end of the year. So the reality is that I'm too stressed and as a result say stupid things. I think I should stop reading slashdot, but the escapism has been useful.