The E in E =mc^2 refers to the rest energy, which is indeed zero for a photon. There's also a component related to motion, and it can be shown from relativity that the total energy is given by E^2 = p^2c^2 + m^2c^4. For a photon of course, this means that E=pc.
Relativistic mass is a rather useless concept, since it doesn't behave as we'd intuitively think that mass would, and is in any case equivalent to the total energy mentioned above. Best to stick to rest mass, which has the useful feature of being independent of frame of reference.
The main problem with Fortran is Fortran programmers. Or, more specifically, those who started off with F77 or earlier and carried on doing things the same way. For numerical stuff, I prefer F90 or later to C - far fewer ways to shoot yourself in the foot with memory management.
(with the disaster spreading to nuclear reactors closer to Tokyo) this would have happened.
What possible mechanism could have caused that? Radioactive leaks aren't like an infectious disease, they don't cause distant power stations to become damaged.
I keep hearing about these $1 per watt solar panels, but whenever I actually look at installed system costs they remain many times that. Combine that with a maybe 20% load factor, and that $5 per watt nuclear's suddenly not looking so bad. And that's before we even get into the costs of storage and backup to handle the intermittency.
I don't see why plonking down 5 megawatts here and there is relevant when the extra capacity the world needs is more like hundreds of gigawatts.
Pumped storage will require an absolutely enormous amount of capacity to store energy in summer and release it in winter. At the moment there isn't much of it and what there is is used mostly for short term balancing - over hours, or maybe a day or two.. Even then, the facilities aren't exactly small. Doing it seasonally and on a large scale will require many orders of magnitude more storage capacity, which is neither cheap nor environmentally benign.
Heat pumps are a nice idea, but I've never heard of them being used to store heat in the ground. I wonder what the round-trip efficiency is.
It's fairly normal for large parts of the electricity generation system to be offline - gas fired plants are fired up to meet peak capacity and are otherwise idle, coal plants have huge, complex turbines, and frequently have one or more of these turbines offline for maintenance, etc.
Maintenance can be scheduled appropriately, and it's extremely unlikely that a large fraction of generators will fail simultaneously. However, it is a certainty that all solar output will drop to zero for several hours every single day. Similarly, wind strength tends to be correlated over a large area, and at least here in the UK, it's common for wind output to drop to under 10% of capacity.
Hydropower from Norway. Wind energy from Denmark (there is more wind in the winter season). Biomass from agriculture waste and forests.
Wind isn't dispatchable, so I can't see how that would help. Does Norway have enough hydro to supply a country the size of Germany? I know it can supply itself nicely with hydro, but Germany has over 15 times the population of Norway. Biomass may well work, but again is there enough of it available without resorting to environmentally destructive measures (like cutting down forests)?
Seasonal affects: electricity demand is usually peak in the summer when people kick their air conditioners in.
Air conditioners? Well, I guess if you live in California, in which case solar may well work well. I know for a fact that peak demand is highest in winter in the UK (where I live). Given its mild climate I suspect that is the same for Germany too.
What kind of storage system can work over seasonal timescales? That's the problem with solar, its production is anticorrelated with demand, producing very little in winter when electricity consumption is at its peak.
If I understand it correctly, it's not "guaranteeing profits" in a sense that the government will pay whatever it costs plus a profit margin. Instead, it's guaranteeing a fixed price for the electricity long term. So they'll have every incentive still to build the plants as cheaply as possible.
If you're going to go down this road though, it would seem to make more sense simply to have the government pay for the plants and recover the income by charging for the electricity. The government can borrow money more cheaply than a private company, after all.
The people who say that Apple is no more expensive for "comparable" hardware ignore that most people don't need anything directly comparable. The people who want some super high end Dell laptop represent a small fraction of the market. For everyone else, "Apple is expensive" is a fair comment - all those extra features aren't worth the extra cost for most people, which is why they don't buy the equivalent PC products either.
IIRC, for that one the exposed group had a different age profile to the unexposed group. As cancer risk increases with age, that explained the difference. Which just goes to show that the idea of a controlled experiment isn't just scientific pedantry - I doubt we'll ever get a satisfactory answer from that kind of study.
That's a very difficult kind of test to do though, because making sure that radiation dose is the *only* difference between groups is virtually impossible. Even the abstract of that paper says that "Further studies will be important to better assess the role of tobacco and other occupational exposures in our risk estimates.". At least this mouse study allows for a proper controlled trial, and the Hiroshima data, while not perfect, is much less prone to such factors than your linked one.
Also, reading the part that says "Among 31 specific types of malignancies studied, a significant association was found for lung cancer (ERR/Sv 1.86, 90% CI 0.49, 3.63; 1457 deaths)" rather reminded me of this.
The interesting thing to note (if this study is correct) is that they observed a difference between an acute dose and a chronic one. Our radiation health data is mostly based on acute doses - the Hiroshima and Nagasaki bombings, mainly. The low dose risk estimates are basically based on that, extrapolated downwards linearly.
If acute dosing behaves differently to chronic, that model wouldn't be appropriate.
It's also really easy to promote social cohesion when 95% of the population is of a single nationality.
That does assume that people won't just find different ways of dividing themselves intro groups - social class, for example, or geographic regions. Just because people are of a single race (a poorly defined concept anyway) or nationality doesn't mean they'll all think the same way.
This phrase shows just how backwards monarchy is. Free speech is not something the government protects. Free speech is something that protects you from the government. If the government can decide which speech to protect, you don't really have free speech at all.
Well, in a sense the government does protect free speech, in that it's the power of the state (police, courts, prisons etc.) which stops someone who didn't like what I said from threatening / assaulting / murdering me. Without that, the only people with free speech would be the strongest.
And the fact that trying to type anything on either a traditional mobile phone keypad or a touchscreen is an exercise in frustration and pain. If someone texts me I either wait until I'm at a PC so I can send an email or, if it can't wait, just phone them.
There's a difference between "not enough to support streaming" and "not enough to support multiple simultaneous streams".
I've just tried watching two simultaneous iPlayer streams, it works fine. Maybe I can't do multiple HD streams, but that's a pretty niche market, and hardly enough to write off ADSL technology. HD falls into the "somewhat nice, but hardly essential" category anyway.
My ADSL connection is 6 Mbps here, which is plenty for streaming. Even my parents can get 2 Mbps on a long telephone line (~ 4 km, 60 dB attenutation), which again is enough for streaming. Well, it works with iPlayer anyway, I haven't tried much else.
Where do you live that a typical ADSL connection is too slow for streaming?
Conservatives believe in a conservative approach to government (imagine that). Extreme conservatism is a very small, relatively weak government. Extreme liberalism is a large, powerful government.
That's not what they mean at all. A theocracy or absolute monarchy would be a very conservative form of government, yet hardly weak. Opposition to gay rights, abortions, racial equality etc. are also conservative positions, yet they involve greater government control over people than their liberal opposition.
Slashdot Mirror
Gas is burned to produce electricity (at efficiencies of no more than about 20-30%),
More like 60% for modern CCGTs. Even older ones should be above 50%, if they haven't been scrapped due to low efficiency.
Well, I guess they have to somehow disguise the fact that watching 30 seconds of sprinting is extremely dull.
The E in E =mc^2 refers to the rest energy, which is indeed zero for a photon. There's also a component related to motion, and it can be shown from relativity that the total energy is given by E^2 = p^2c^2 + m^2c^4. For a photon of course, this means that E=pc.
Relativistic mass is a rather useless concept, since it doesn't behave as we'd intuitively think that mass would, and is in any case equivalent to the total energy mentioned above. Best to stick to rest mass, which has the useful feature of being independent of frame of reference.
The main problem with Fortran is Fortran programmers. Or, more specifically, those who started off with F77 or earlier and carried on doing things the same way. For numerical stuff, I prefer F90 or later to C - far fewer ways to shoot yourself in the foot with memory management.
(with the disaster spreading to nuclear reactors closer to Tokyo) this would have happened.
What possible mechanism could have caused that? Radioactive leaks aren't like an infectious disease, they don't cause distant power stations to become damaged.
Yes, it says you haven't got a clue how to travel in London.
Why would he, if he doesn't live there?
London is a hellishly complicated place, and how many people who don't live there have bus/taxi/tube/walking routes memorised?
I keep hearing about these $1 per watt solar panels, but whenever I actually look at installed system costs they remain many times that. Combine that with a maybe 20% load factor, and that $5 per watt nuclear's suddenly not looking so bad. And that's before we even get into the costs of storage and backup to handle the intermittency.
I don't see why plonking down 5 megawatts here and there is relevant when the extra capacity the world needs is more like hundreds of gigawatts.
Virgin isn't "full fibre", it's HFC like every other cable TV network.
Their advertising campaign was obviously effective at getting their "fibre" message across.
Pumped storage will require an absolutely enormous amount of capacity to store energy in summer and release it in winter. At the moment there isn't much of it and what there is is used mostly for short term balancing - over hours, or maybe a day or two.. Even then, the facilities aren't exactly small. Doing it seasonally and on a large scale will require many orders of magnitude more storage capacity, which is neither cheap nor environmentally benign.
Heat pumps are a nice idea, but I've never heard of them being used to store heat in the ground. I wonder what the round-trip efficiency is.
It's fairly normal for large parts of the electricity generation system to be offline - gas fired plants are fired up to meet peak capacity and are otherwise idle, coal plants have huge, complex turbines, and frequently have one or more of these turbines offline for maintenance, etc.
Maintenance can be scheduled appropriately, and it's extremely unlikely that a large fraction of generators will fail simultaneously. However, it is a certainty that all solar output will drop to zero for several hours every single day. Similarly, wind strength tends to be correlated over a large area, and at least here in the UK, it's common for wind output to drop to under 10% of capacity.
Hydropower from Norway. Wind energy from Denmark (there is more wind in the winter season). Biomass from agriculture waste and forests.
Wind isn't dispatchable, so I can't see how that would help. Does Norway have enough hydro to supply a country the size of Germany? I know it can supply itself nicely with hydro, but Germany has over 15 times the population of Norway. Biomass may well work, but again is there enough of it available without resorting to environmentally destructive measures (like cutting down forests)?
Seasonal affects: electricity demand is usually peak in the summer when people kick their air conditioners in.
Air conditioners? Well, I guess if you live in California, in which case solar may well work well. I know for a fact that peak demand is highest in winter in the UK (where I live). Given its mild climate I suspect that is the same for Germany too.
What kind of storage system can work over seasonal timescales? That's the problem with solar, its production is anticorrelated with demand, producing very little in winter when electricity consumption is at its peak.
If I understand it correctly, it's not "guaranteeing profits" in a sense that the government will pay whatever it costs plus a profit margin. Instead, it's guaranteeing a fixed price for the electricity long term. So they'll have every incentive still to build the plants as cheaply as possible.
If you're going to go down this road though, it would seem to make more sense simply to have the government pay for the plants and recover the income by charging for the electricity. The government can borrow money more cheaply than a private company, after all.
The people who say that Apple is no more expensive for "comparable" hardware ignore that most people don't need anything directly comparable. The people who want some super high end Dell laptop represent a small fraction of the market. For everyone else, "Apple is expensive" is a fair comment - all those extra features aren't worth the extra cost for most people, which is why they don't buy the equivalent PC products either.
IIRC, for that one the exposed group had a different age profile to the unexposed group. As cancer risk increases with age, that explained the difference. Which just goes to show that the idea of a controlled experiment isn't just scientific pedantry - I doubt we'll ever get a satisfactory answer from that kind of study.
That's a very difficult kind of test to do though, because making sure that radiation dose is the *only* difference between groups is virtually impossible. Even the abstract of that paper says that "Further studies will be important to better assess the role of tobacco and other occupational exposures in our risk estimates.". At least this mouse study allows for a proper controlled trial, and the Hiroshima data, while not perfect, is much less prone to such factors than your linked one.
Also, reading the part that says "Among 31 specific types of malignancies studied, a significant association was found for lung cancer (ERR/Sv 1.86, 90% CI 0.49, 3.63; 1457 deaths)" rather reminded me of this.
The interesting thing to note (if this study is correct) is that they observed a difference between an acute dose and a chronic one. Our radiation health data is mostly based on acute doses - the Hiroshima and Nagasaki bombings, mainly. The low dose risk estimates are basically based on that, extrapolated downwards linearly.
If acute dosing behaves differently to chronic, that model wouldn't be appropriate.
It's also really easy to promote social cohesion when 95% of the population is of a single nationality.
That does assume that people won't just find different ways of dividing themselves intro groups - social class, for example, or geographic regions. Just because people are of a single race (a poorly defined concept anyway) or nationality doesn't mean they'll all think the same way.
This phrase shows just how backwards monarchy is. Free speech is not something the government protects. Free speech is something that protects you from the government. If the government can decide which speech to protect, you don't really have free speech at all.
Well, in a sense the government does protect free speech, in that it's the power of the state (police, courts, prisons etc.) which stops someone who didn't like what I said from threatening / assaulting / murdering me. Without that, the only people with free speech would be the strongest.
And the fact that trying to type anything on either a traditional mobile phone keypad or a touchscreen is an exercise in frustration and pain. If someone texts me I either wait until I'm at a PC so I can send an email or, if it can't wait, just phone them.
Most bafflingly popular feature ever.
There's a difference between "not enough to support streaming" and "not enough to support multiple simultaneous streams".
I've just tried watching two simultaneous iPlayer streams, it works fine. Maybe I can't do multiple HD streams, but that's a pretty niche market, and hardly enough to write off ADSL technology. HD falls into the "somewhat nice, but hardly essential" category anyway.
My ADSL connection is 6 Mbps here, which is plenty for streaming. Even my parents can get 2 Mbps on a long telephone line (~ 4 km, 60 dB attenutation), which again is enough for streaming. Well, it works with iPlayer anyway, I haven't tried much else.
Where do you live that a typical ADSL connection is too slow for streaming?
Conservatives believe in a conservative approach to government (imagine that). Extreme conservatism is a very small, relatively weak government. Extreme liberalism is a large, powerful government.
That's not what they mean at all. A theocracy or absolute monarchy would be a very conservative form of government, yet hardly weak. Opposition to gay rights, abortions, racial equality etc. are also conservative positions, yet they involve greater government control over people than their liberal opposition.
The article says it's about 200 MW, which is much larger than the 4S. It's probably Westinghouse's new SMR.
Or at least Westinghouse's claimed SMR - I don't think they've actually got a worked out design yet.