That's indistinguishable from background noise a few light years out. Hence the entire point of this study on how to purposefully send a signal that is distinguishable at a distance.
No. Check your facts.
He's correct: our RF broadcasts are indistinguishable from background noise at even a few parsecs distance. The stars turn out to be a very very long way away.
There are two exceptions: the Arecibo planetary radar, and ballistic missile warning radars.
But the Arecibo dish is very rarely used as radar, and if it did by coincidence happen to illuminate a star with inhabited planets behind the planet it was looking at... it's likely that it would never point that direction again, ever. The aliens would see one bright blip--if they were looking with an Arecibo sized radio telescope at the right frequency at exactly the right time--but if they look again, nothing.
Ballistic missile warning radar would be more repeatable, but it sweeps small parts of near-polar sky with a repeat time of 24 hours. So, if they see the blip as the radar passes over their star, unless they look again exactly 24 hours later, again, they won't see anything.
And, at a hundred parsecs, even those signals are too faint to detect-- they're swamped by the background. The galaxy is 100 thousand parsecs across. So, no: most of the galaxy couldn't hear us even if they had Arecibo-sized telescopes listening.
If it is concentrated more in the home where someone lives gaining heat from any combustion source tuned incorrectly then your pie chart is irrelevant. It needs to be sampled at the dwelling
Indoor sources don't burn hot enough to produce nitrogen oxides.
There's also no immigration reform, which Obama ran on in 2008 and talked up for a good chunk of 2009, when democrats had control of the house AND senate.
And, amusingly, so did George Bush, when he had control of both the house and the senate.
Well, America's space program was built by Nazis we snatched up before the Soviets could grab them.
Partly. There was also a US program (in fact, several US programs: the GALCIT team in California didn't work at all with Goddard's team in New Mexico). It's easy to point out that when Vanguard (based on the Navy rocket program) failed, the Army team launched Explorer 1 on the Juno booster, based on the Von Braun team's Jupiter. It's often forgotten, however, that Juno was a four stage booster, and only the first stage was the Jupiter: the second, third, and fourth stages -- the parts that actually took it to orbit-- were from JPL developed rockets.
Not sure why you credit the paper by Turco, Toon, Ackerman, Pollack, and Sagan to just "Sagan". Since you don't seem to even know who wrote the paper, I can scarcely pay much attention to your other opinions on it.
It was an interesting paper. Turns out it was a bit optimistic about the amount of ash that can be injected into the stratosphere by firestorms, but I don't think you could call it "fudged"-- it was an interesting analysis.
"Once the darling of design" is right. Actual research shows that the "open office" idea, with no privacy at all, is a terrible idea for a workplace, which maximized distractions and minimized getting things done.
When it gets too hot just have a few Tsar bomba go off in Siberia and you will have a nuclear winer. Problem solved
Turns out not. The "nuclear winter" scenario assumed over a hundred city firestorms lifting ash into the stratosphere. I'm not sure how flammable Siberia is, but you probably couldn't get enough burning to sustain the kind of massive firestorm needed.
So, a car that does short trips all-electric but has a gas engine for back-up is, for most trips, an all electric car, but one that also works for longer trips.
Electric cars are REALLY powered by coal. Especially in California. California just imports the electricity made from coal in many plants in UTAH.
Even accounting for imports, California electrical power is only 4% from coal. In fact, California electricity is mostly natural gas. Figures are here https://www.energy.ca.gov/.
Then they just smuggly think they are green. Those solar plants don't REALLY make that much energy.
This can be solved by reprocessing spent fuel, and by going to breeder reactors. But governments don't want to do that because of fear of nuclear terrorism.
They fear terrorism more than global warming?
Good God, yes!
A handful of nuclear bombs could seriously damage the Earth, and right now.
Global warming, on the other hand, is a long term effect.
I always found it fascinating that CO2 levels moving from 200ppm (0.0002) to 400ppm (0.0004), a change of 0.0002, is the cause of all this warming.
Yes, isn't it fascinating? The fact that small fractions of trace gasses can dominate the atmospheric infrared absorption was discovered by John Tyndall in 1859. https://earthobservatory.nasa.... We now know that this is because the tightly-bound diatomic molecules don't have vibrational modes in the infrared energy range, of course, but at the time, it was indeed quite fascinating that miniscule amounts of water and carbon dioxide could absorb more than the vastly larger concentration of oxygen and nitrogen in the atmosphere.
Tyndall was quite an amazing man. He's also the person credited with coming up with the first reasonable answer to the question "why is the sky blue"? https://www.bbvaopenmind.com/e... (his answer was "scattering", which is right as far as it goes, but of course it took the mathematics of Rayleigh scattering fifty years later to understand the actual details.)
In this particular case, you get your wish: the discussion here is about vehicles to launch satellites, not weapons.
For a long time, the same basic boosters had been used for both applications: the orbital launch vehicles were adapted from missiles. But now, that is no longer the case; none of the current generation of orbital vehicles is adapted from a missile
Half right. It is big, but it is not expensive. Turns out water is cheap.
and results in more energy usage, not less.
Slightly more; depending on exactly how you use it. It can actually be more efficient, if the air conditioning peak is spread out over a longer time, or less efficient if you're narrowing it down over a shorter time span. Not actually a big effect, though.
It does offset the afternoon peak demand in exchange for more energy consumption at night, which saves money by increasing the use factor for those big, base-load power plants.
That's also a possible use for thermal storage, yes. Different from the one I mentioned. That application is one of the cases where the thermal storage approach is actually more efficient than using air conditioning when you need it (by running at night, you reject heat at lower temperature.) But, again, the difference is in most cases small.
Unfortunately, that is just the opposite of what you want if you're generating with photovoltaics.
No, it's exactly the same: you run when energy is cheap, instead of when energy is expensive. The time of day that energy is cheap will depend on your energy source (9am to 3 pm for solar, midnight to 6am for coal), but the basic concept, that the price of energy depends on time of day, so you use thermal storage to use the cheap energy, is the same.
If you want to reduce coal consumption, the best, most cost effective, and politically acceptable solution, is better ACs.
ACs are about as good as they can get right now, especially in developing countries....
But the increasing demand can only be accounted for by new AC installations. Anything old would be existing and already part of the load prior to the increase in demand that's prompting new powerplant construction.
Actually, since electrical power from solar arrays is becoming extremely low cost during the daytime, replacing air conditioning would be a great way to reduce carbon footprint, if you run it only during the daytime.
Turns out that thermal storage is relatively simple in the range of temperatures used by air conditioning: water has an enormous heat capacity, and is cheap. Cool the water during the day, use the stored thermal mass to cool during the night.
(And water has significantly more thermal capacity if you use the phase change to ice.)
This does, however, only make sense if you have either time-dependent electrical rate (if electricity isn't cheaper during the day, no incentive to buy a thermal-storage Air Conditioner), or else your residence/office building is cooling with its own solar panels.
I have to point out that perovskites have been the hot research topic for low-cost solar cells for several years now. It's nice that slashdot suddenly noticed them, but mentioning one research group, while ignoring a hundred other research groups working on perovskite solar cells, is a little misleading.
Slashdot Mirror
The actual research paper being discussed is here: https://scholarcommons.usf.edu...
Anyone with a red hat, you need to vote next month as it's national red hat month and you'll get twice the voting power if you save it up.
Hey! What do you have against Linux users?
That's indistinguishable from background noise a few light years out. Hence the entire point of this study on how to purposefully send a signal that is distinguishable at a distance.
No. Check your facts.
He's correct: our RF broadcasts are indistinguishable from background noise at even a few parsecs distance. The stars turn out to be a very very long way away.
There are two exceptions: the Arecibo planetary radar, and ballistic missile warning radars.
But the Arecibo dish is very rarely used as radar, and if it did by coincidence happen to illuminate a star with inhabited planets behind the planet it was looking at... it's likely that it would never point that direction again, ever. The aliens would see one bright blip--if they were looking with an Arecibo sized radio telescope at the right frequency at exactly the right time--but if they look again, nothing.
Ballistic missile warning radar would be more repeatable, but it sweeps small parts of near-polar sky with a repeat time of 24 hours. So, if they see the blip as the radar passes over their star, unless they look again exactly 24 hours later, again, they won't see anything.
And, at a hundred parsecs, even those signals are too faint to detect-- they're swamped by the background. The galaxy is 100 thousand parsecs across. So, no: most of the galaxy couldn't hear us even if they had Arecibo-sized telescopes listening.
What, nobody has posted the obligatory xkcd yet?
fish.
... and also, are you sure we're looking for the right thing? ants
If it is concentrated more in the home where someone lives gaining heat from any combustion source tuned incorrectly then your pie chart is irrelevant. It needs to be sampled at the dwelling
Indoor sources don't burn hot enough to produce nitrogen oxides.
There's also no immigration reform, which Obama ran on in 2008 and talked up for a good chunk of 2009, when democrats had control of the house AND senate.
And, amusingly, so did George Bush, when he had control of both the house and the senate.
(Interestingly, Bush's immigration reform plan was nearly the same as Obama's.)
...That's because the democrats are a very fractured party at the moment.
Actually, given that I don't always like what happens when a unified party gains control, there's a lot to be said for voting for a fractured party.
Neither party have a compelling message at the moment. Republicans: "Make America White Again"
Democrats: "We're not with Stupid."
Say, I support that as a slogan!
One of Akin's laws of spacecraft design is "Don't do nothin' dumb."
??
They're blaming nitrogen dioxide. Nitrogen dioxide is not CO2.
Sources of atmospheric nitrogen dioxide:
https://www3.epa.gov/region1/airquality/images/nox.gif
My understanding is that Juno was von Braun's design --
As I said: the Juno vehicle used the Von Braun team's Jupiter as the first stage. The other three stages of the four-stage design were JPL.
Well, America's space program was built by Nazis we snatched up before the Soviets could grab them.
Partly. There was also a US program (in fact, several US programs: the GALCIT team in California didn't work at all with Goddard's team in New Mexico). It's easy to point out that when Vanguard (based on the Navy rocket program) failed, the Army team launched Explorer 1 on the Juno booster, based on the Von Braun team's Jupiter. It's often forgotten, however, that Juno was a four stage booster, and only the first stage was the Jupiter: the second, third, and fourth stages -- the parts that actually took it to orbit-- were from JPL developed rockets.
Yes, I'm sorry for them, but many, many examples tells us that most first tries at building an orbital booster fail.
The biggest part of success in rocket building is the ability to accept a failure, learn from it, and keep on.
Not sure why you credit the paper by Turco, Toon, Ackerman, Pollack, and Sagan to just "Sagan". Since you don't seem to even know who wrote the paper, I can scarcely pay much attention to your other opinions on it.
It was an interesting paper. Turns out it was a bit optimistic about the amount of ash that can be injected into the stratosphere by firestorms, but I don't think you could call it "fudged"-- it was an interesting analysis.
" I say Venus may be the second most Earth-like location in the solar system." Well, that's bullshit.
No, at the right altitude-- about 56 km above the surface-- Venus is remarkably Earthlike.
No oxygen, of course, but in temperature and pressure, very close.
I wrote a paper about this: "Colonization of Venus", back in 2003. Glad to see my work is being taken seriously!
"Once the darling of design" is right. Actual research shows that the "open office" idea, with no privacy at all, is a terrible idea for a workplace, which maximized distractions and minimized getting things done.
When it gets too hot just have a few Tsar bomba go off in Siberia and you will have a nuclear winer. Problem solved
Turns out not. The "nuclear winter" scenario assumed over a hundred city firestorms lifting ash into the stratosphere. I'm not sure how flammable Siberia is, but you probably couldn't get enough burning to sustain the kind of massive firestorm needed.
Most car trips are under 6 miles. 75% of all car trips are under 10 miles.
https://247wallst.com/autos/20...
So, a car that does short trips all-electric but has a gas engine for back-up is, for most trips, an all electric car, but one that also works for longer trips.
Electric cars are REALLY powered by coal. Especially in California. California just imports the electricity made from coal in many plants in UTAH.
Even accounting for imports, California electrical power is only 4% from coal. In fact, California electricity is mostly natural gas. Figures are here
https://www.energy.ca.gov/.
Then they just smuggly think they are green. Those solar plants don't REALLY make that much energy.
About 10% solar, and another 9.4% wind generation. Actually, now that I look up the numbers, I'm impressed-- that's more than I'd expected. Graph here: https://en.wikipedia.org/wiki/Energy_in_California#/media/File:California_Electricity_Generation_Sources_Pie_Chart.svg/a?
Prius is not an electric car, you fucking idiot.
The Prius Prime (aka "Plug-in Prius") is.
It has an internal combustion back-up for long trips, but unless you do long road trips, it's pure electric.
This can be solved by reprocessing spent fuel, and by going to breeder reactors. But governments don't want to do that because of fear of nuclear terrorism.
They fear terrorism more than global warming?
Good God, yes!
A handful of nuclear bombs could seriously damage the Earth, and right now.
Global warming, on the other hand, is a long term effect.
I always found it fascinating that CO2 levels moving from 200ppm (0.0002) to 400ppm (0.0004), a change of 0.0002, is the cause of all this warming.
Yes, isn't it fascinating? The fact that small fractions of trace gasses can dominate the atmospheric infrared absorption was discovered by John Tyndall in 1859. https://earthobservatory.nasa....
We now know that this is because the tightly-bound diatomic molecules don't have vibrational modes in the infrared energy range, of course, but at the time, it was indeed quite fascinating that miniscule amounts of water and carbon dioxide could absorb more than the vastly larger concentration of oxygen and nitrogen in the atmosphere.
Tyndall was quite an amazing man. He's also the person credited with coming up with the first reasonable answer to the question "why is the sky blue"? https://www.bbvaopenmind.com/e...
(his answer was "scattering", which is right as far as it goes, but of course it took the mathematics of Rayleigh scattering fifty years later to understand the actual details.)
I hope the pentagon chooses missiles for peace.
In this particular case, you get your wish: the discussion here is about vehicles to launch satellites, not weapons.
For a long time, the same basic boosters had been used for both applications: the orbital launch vehicles were adapted from missiles. But now, that is no longer the case; none of the current generation of orbital vehicles is adapted from a missile
Thermal storage using water is big and expensive
Half right. It is big, but it is not expensive. Turns out water is cheap.
and results in more energy usage, not less.
Slightly more; depending on exactly how you use it. It can actually be more efficient, if the air conditioning peak is spread out over a longer time, or less efficient if you're narrowing it down over a shorter time span. Not actually a big effect, though.
It does offset the afternoon peak demand in exchange for more energy consumption at night, which saves money by increasing the use factor for those big, base-load power plants.
That's also a possible use for thermal storage, yes. Different from the one I mentioned. That application is one of the cases where the thermal storage approach is actually more efficient than using air conditioning when you need it (by running at night, you reject heat at lower temperature.) But, again, the difference is in most cases small.
Unfortunately, that is just the opposite of what you want if you're generating with photovoltaics.
No, it's exactly the same: you run when energy is cheap, instead of when energy is expensive. The time of day that energy is cheap will depend on your energy source (9am to 3 pm for solar, midnight to 6am for coal), but the basic concept, that the price of energy depends on time of day, so you use thermal storage to use the cheap energy, is the same.
If you want to reduce coal consumption, the best, most cost effective, and politically acceptable solution, is better ACs.
ACs are about as good as they can get right now, especially in developing countries. ...
But the increasing demand can only be accounted for by new AC installations. Anything old would be existing and already part of the load prior to the increase in demand that's prompting new powerplant construction.
Actually, since electrical power from solar arrays is becoming extremely low cost during the daytime, replacing air conditioning would be a great way to reduce carbon footprint, if you run it only during the daytime.
Turns out that thermal storage is relatively simple in the range of temperatures used by air conditioning: water has an enormous heat capacity, and is cheap. Cool the water during the day, use the stored thermal mass to cool during the night.
(And water has significantly more thermal capacity if you use the phase change to ice.)
This does, however, only make sense if you have either time-dependent electrical rate (if electricity isn't cheaper during the day, no incentive to buy a thermal-storage Air Conditioner), or else your residence/office building is cooling with its own solar panels.
I have to point out that perovskites have been the hot research topic for low-cost solar cells for several years now. It's nice that slashdot suddenly noticed them, but mentioning one research group, while ignoring a hundred other research groups working on perovskite solar cells, is a little misleading.
For more information, here are 33,000 papers to read: https://scholar.google.com/sch...