This is a cool idea, but do the math: if you were able to shut off the reported 0.1 kg/s of atmospheric mass loss, how long does it take to double the atmospheric mass (about 2.5 x 10^16 kg)?
Related question: does it count as terraforming if the Sun blows up before you finish the job?
Okay, looks like it’s time to dust off my post-election-day secession rant.
The dividing lines in this country are as clear as a jigsaw puzzle. But like a jigsaw puzzle, the pieces are so tightly interlocked that there’s no way to pull it apart without wrecking everything.
Let’s start by ignoring what the Constitution says: if somebody’s splitting off from the US, its laws are not theirs to follow. Never mind legality or morality, let’s just ask, can parts of the US secede without killing millions and impoverishing us all? Those are the stakes.
Borders. Let’s take the Northeast as an example, from Maine to New York. Solid blue states, easy enough to make a nice country out of. Well, except for most of New Hampshire. And upstate New York. And central Massachusetts and inland Maine, and Staten Island, and the town I live in near Boston... if secession is on the table, what’s to stop these regions from seceding from their states? Suddenly your country looks more like a federation of city-states, surrounded by hostile rural territory. America’s internal border is fractal, from the national level right down to individual bedrooms. If you insist on contiguous state borders, what are your options? Call out the state militia to occupy rebellious Staten Island? Partition and forced emigration? Ask India and Pakistan how that worked out.
But let’s suppose you get the territory bit worked out. What about the national debt? If a breakaway republic leaves the US without taking its fair share of the national debt, it’s effectively stolen trillions of dollars. If it gets away with it, everyone else will break away too, the debt will be abandoned, and every T-bill on the planet will become worthless. That’s $18 trillion of investment wiped out, a scale of debt write-off at least times worse than the mortgage crisis of 2007, a hundred times worse than Greece. This is your social security money, your pension, wiped out instantly. And if a breakaway republic *does* take its share of debt, a small young unstable nation isn’t going to be offered the same interest rates the USA gets. It'll immediately find itself in a Greek-style debt crisis.
The federal government owns a lot of stuff, and some of it is hard to move. What happens to the mineral rights, national parks, military bases, federal buildings, and post offices in a breakaway republic? Will it pay the US fair market value for them? Because they can’t afford to. If they seize them by force, is the US justified in reclaiming its property violently? Speaking of violence, what happens to the aircraft carriers and F-22s? Who gets the nukes? I don’t want them, but if I’m going to share a continent with a bunch of nuclear-armed belligerent xenophobic nationalists, I might need some.
With this much to fight over, it’s clear that two divided Americas would be hostile to each other, possibly at war, but each would have lots of citizens who sympathize with the other side. The history of minority groups who sympathize with the enemy is long and bloody. Iraqi Shias. Japanese-Americans during World War 2. Rwanda.
Dividing a country turns its internal conflicts into external conflicts. Internal conflicts can be solved through politics, but the main way nations solve external conflicts is through economic and/or literal war. It’s naive to believe that partition would be peaceful: civil war, forced emigration, or global economic collapse are pretty likely. Maybe you think the risk of these is low enough that it’s worth a shot. I don’t.
If you're upset that plate scanners are being used for mass surveillance, that's fine. If you're upset that plate scanners are being used for mass surveillance of a legal activity you really care about, you're part of the problem.
It's all about our expectations of energy density. Think about it: would you be surprised to hear that a small container of gasoline caught fire? Of course not, and the risks involved in a gas-powered phone are obvious. Modern batteries don't store as much energy per mass as gasoline -- not even close -- but as we push in that direction we shouldn't be surprised that they start behaving less like electronics and more like explosives.
It is, however, racist to ignore the fact that almost 100% of the results for "three black teenagers" are mugshots, while only a small fraction of black teenagers are actually criminals. It's also racist to believe that we as a society have nothing to do with creating a criminal underclass along racial lines.
I'm sorry, isn't this completely f***ing obvious? I mean all of it, that society is racist and that Google search results reflect that racism. I don't care whether you're 18 or 80, this really shouldn't be a surprise.
I think I can answer that based on my extensive training with Kerbal Space Program. And okay some stuff I read about the moon landings too. If you come straight down and find you're going to land off-target, you have to swivel the engine sideways, burn to build up some horizontal velocity, and then swivel in the other direction to cancel it out again. But if you keep some sideways velocity as you descend, it's easy to adjust your final landing point in that direction by starting your final deceleration burn a little early or late. It's still tricky in the other horizontal direction, of course.
You make a very good point for, say, satellite delivery, where being in space at all is much more valuable than how many pounds the satellite weighs. But for ISS resupply, what NASA cares about for its COTS program is total tonnage reliably delivered. And SpaceX's stated goal has always been reducing the cost of bulk cargo delivery, with "dollars per pound" as the metric of success.
SpaceX, and the people in this thread, are comparing the vehicle cost to fuel cost, which is kinda cheating. It's not the cost of the fuel that matters, it's the cost of building the vehicle larger to hold that fuel -- and the fuel needed to launch that fuel -- that matters. So let's do the math!
Most data taken from http://spaceflight101.com/spac... Basic info: Stage 1: 23 tonnes structure, 400 tonnes fuel Stage 2: 4 tonnes structure, 93 tonnes fuel Payload: 13 tonnes
When launching, the first stage burns all 9 engines at full thrust for two and a half minutes. The re-entry burn and landing happen on a single engine, and from eyeballing the videos (including this one that shows the re-entry burn) appear to take about 30 seconds total. Assuming all burns are near full thrust (which is the best way to do it), that means the landing burn takes about (1/9) * (0:30 / 2:30) = 2% of the first stage fuel. Let's double that to 4% to provide a generous safety margin: that works out to about 400 * 0.04 = 16 tons more fuel.
This fuel is carried up to the moment that the second stage separates, so it subtracts from the mass of the second stage. Second stage plus payload weighs 110 tonnes: without the landing fuel, you could have scaled that up to 126 tonnes, a 15% increase.
So, landing the first stage reduces the payload SpaceX can launch, and thus the money they earn, by about 15%. In exchange, they recover about 75% of the cost of the launch hardware. So it's worth doing, even after you subtract off the cost of recovery and refurbishing. Maybe not the game-changer Elon Musk wants it to be, but it's a win.
If I had utterly failed to consider the possibility, I wouldn't have spent a couple sentences speculating on how it might be done. Could there be some revolution in optics I've never heard of? Sure, that's why I'm asking. Could a company have patented an idea they have no idea how to implement, so they can patent troll in the future? Well gosh, that never happens.
This has gotta be bullshit, or at least a conceptual patent (which is another word for bullshit), right?
From everything I know about optics -- and I teach college physics, so I'm not clueless -- if you put a video screen on the surface of the eyeball all you'll see is a colored blur over your whole field of vision. What matters is not the location of the light source on your cornea, but the *direction* it's coming from: any workable video screen would need to work kinda like a phased-array radar, but a million times smaller. Or something like the Lytro light field camera in reverse.
But while I can think of ways in which such a thing *could* work, with current technology this is utterly impossible. Anybody better-informed than me care to weigh in?
The risk of hurting the eagle really makes this a bad idea. If only there was some sort of machine that could do this job, like a robo-eagle? It'd have to be an agile remote-controlled flying machine which used a camera to send images back to the operator.
Because a controlled experiment involving the actual Earth would mean telling a few billion people they have to keep their population, technology, and society constant for a century, and a) nobody's gonna agree to that, and b) if they did there wouldn't be an issue.
Just to pick the top story on that realclimatescience.com site: it's looking at NOAA's statement that 2015 had record *average* temperatures in the US, and is rebutting with data on the *frequency of hot days* in the US, which is an entirely different idea. Since greenhouse gases control the rate at which energy *leaves* the earth to cooling it down, you would predict it should warm the coolest days more than the warmest. Which is exactly what's happened. IPCC report finds, globally, a significant increase in night and winter temperatures, a statistically insignificant change in temperature of the hottest days.
The match between theoretical prediction, and basic physics is the best way to assess the truth. You'll notice that the denialists will try to poke holes in the standard global warming story, but very rarely will they show show that their revised data agrees with a physical theory. (In particular, if CO2 and water vapor concentrations are rising, why *doesn't* that cause global warming in their view? By everything we know about these gases, it should.)
[E] is not possible when the experiment is being carried out over centuries, with a civilization growing inside the test chamber. [D] leads to biases (chiefly the urban heat island effect) which *increase* the apparent trend (see Layzej's reply). If you don't correct for them, global warming looks *worse* than it actually is.
Your point that most cemeteries are eventually reused is well taken, though Americans are very *very* resistant to that, probably because they can afford to be.
Having some green spots in the city is hardly an "environmental problem"
Agree, except that it's a non-renewable resource: once a cemetery, always a cemetery, and there's a social taboo against using them as public parks or letting them revert to nature. I first started thinking about this when my commute took me past some of the big cemeteries on the north side of Chicago. Square miles filled with the corpses of just one century's worth of Chicagoans. Give it another few centuries, and the dead will own more land than the living.
Let me break it down for you: I eat my weight in plants and animals about every six months or so. So the amount of biomass in my actual body is less than 1% of the biomass in the food I ate, and the inedible plant and animal parts I threw away. You can try to recycle your body if you want to, it's a nice gesture, but it's an insignificant part of the environmental problem.
(You're also wrong on the biochemistry, "useful proteins and specialized molecules" are not assembled over centuries and preserved through the food web. Plants build all their complex biomolecules from scratch; animals break the biomolecules in their food down into simple organics and reassemble them.)
Yes, cremation requires energy input: my point all along has been that that input is tiny compared to what a living human uses over any length of time: it amounts to a few kg of carbon. Your post doesn't counter that point.
Accumulated mercury doesn't go away during cremation, but people typically keep the cremains rather than dumping them back into their food supply, and crematoria are starting to take this issue seriously. And yes, all animals pose a drug and pathogen risk even now, which is why we typically render them rather than composting, and we take extra special care when recycling animal parts and waste back into the food supply. If you don't, you get e. coli infested vegetables, mad cow disease, etc.
In any case, my point was not that composting is definitely a serious threat, but that the potential risks aren't worth the tiny benefit.
Slashdot Mirror
Billions.
This is a cool idea, but do the math: if you were able to shut off the reported 0.1 kg/s of atmospheric mass loss, how long does it take to double the atmospheric mass (about 2.5 x 10^16 kg)?
Related question: does it count as terraforming if the Sun blows up before you finish the job?
This just in: Researchers report that 600,000 is a very big number that you should be super impressed by. That is all.
Okay, looks like it’s time to dust off my post-election-day secession rant.
The dividing lines in this country are as clear as a jigsaw puzzle. But like a jigsaw puzzle, the pieces are so tightly interlocked that there’s no way to pull it apart without wrecking everything.
Let’s start by ignoring what the Constitution says: if somebody’s splitting off from the US, its laws are not theirs to follow. Never mind legality or morality, let’s just ask, can parts of the US secede without killing millions and impoverishing us all? Those are the stakes.
Borders. Let’s take the Northeast as an example, from Maine to New York. Solid blue states, easy enough to make a nice country out of. Well, except for most of New Hampshire. And upstate New York. And central Massachusetts and inland Maine, and Staten Island, and the town I live in near Boston... if secession is on the table, what’s to stop these regions from seceding from their states? Suddenly your country looks more like a federation of city-states, surrounded by hostile rural territory. America’s internal border is fractal, from the national level right down to individual bedrooms. If you insist on contiguous state borders, what are your options? Call out the state militia to occupy rebellious Staten Island? Partition and forced emigration? Ask India and Pakistan how that worked out.
But let’s suppose you get the territory bit worked out. What about the national debt? If a breakaway republic leaves the US without taking its fair share of the national debt, it’s effectively stolen trillions of dollars. If it gets away with it, everyone else will break away too, the debt will be abandoned, and every T-bill on the planet will become worthless. That’s $18 trillion of investment wiped out, a scale of debt write-off at least times worse than the mortgage crisis of 2007, a hundred times worse than Greece. This is your social security money, your pension, wiped out instantly. And if a breakaway republic *does* take its share of debt, a small young unstable nation isn’t going to be offered the same interest rates the USA gets. It'll immediately find itself in a Greek-style debt crisis.
The federal government owns a lot of stuff, and some of it is hard to move. What happens to the mineral rights, national parks, military bases, federal buildings, and post offices in a breakaway republic? Will it pay the US fair market value for them? Because they can’t afford to. If they seize them by force, is the US justified in reclaiming its property violently? Speaking of violence, what happens to the aircraft carriers and F-22s? Who gets the nukes? I don’t want them, but if I’m going to share a continent with a bunch of nuclear-armed belligerent xenophobic nationalists, I might need some.
With this much to fight over, it’s clear that two divided Americas would be hostile to each other, possibly at war, but each would have lots of citizens who sympathize with the other side. The history of minority groups who sympathize with the enemy is long and bloody. Iraqi Shias. Japanese-Americans during World War 2. Rwanda.
Dividing a country turns its internal conflicts into external conflicts. Internal conflicts can be solved through politics, but the main way nations solve external conflicts is through economic and/or literal war. It’s naive to believe that partition would be peaceful: civil war, forced emigration, or global economic collapse are pretty likely. Maybe you think the risk of these is low enough that it’s worth a shot. I don’t.
"Are [publishers] liable for what their users print?" No, unless they knowingly help their users commit a crime. Which Backpage allegedly did.
If you're upset that plate scanners are being used for mass surveillance, that's fine. If you're upset that plate scanners are being used for mass surveillance of a legal activity you really care about, you're part of the problem.
Don't make me quote Martin Neimoller at ya.
It's all about our expectations of energy density. Think about it: would you be surprised to hear that a small container of gasoline caught fire? Of course not, and the risks involved in a gas-powered phone are obvious. Modern batteries don't store as much energy per mass as gasoline -- not even close -- but as we push in that direction we shouldn't be surprised that they start behaving less like electronics and more like explosives.
Got a citation for this quote? It's fantastic, but a Google search turns up nothing but this thread...
If it didn't have micro-fractures before, it sure does now... and they're definitely going to be hard to find.
It is, however, racist to ignore the fact that almost 100% of the results for "three black teenagers" are mugshots, while only a small fraction of black teenagers are actually criminals. It's also racist to believe that we as a society have nothing to do with creating a criminal underclass along racial lines.
I'm sorry, isn't this completely f***ing obvious? I mean all of it, that society is racist and that Google search results reflect that racism. I don't care whether you're 18 or 80, this really shouldn't be a surprise.
What about zero? Zero is an exponent. By that measure, my love life is improving exponentially...
I think I can answer that based on my extensive training with Kerbal Space Program. And okay some stuff I read about the moon landings too. If you come straight down and find you're going to land off-target, you have to swivel the engine sideways, burn to build up some horizontal velocity, and then swivel in the other direction to cancel it out again. But if you keep some sideways velocity as you descend, it's easy to adjust your final landing point in that direction by starting your final deceleration burn a little early or late. It's still tricky in the other horizontal direction, of course.
You make a very good point for, say, satellite delivery, where being in space at all is much more valuable than how many pounds the satellite weighs. But for ISS resupply, what NASA cares about for its COTS program is total tonnage reliably delivered. And SpaceX's stated goal has always been reducing the cost of bulk cargo delivery, with "dollars per pound" as the metric of success.
SpaceX, and the people in this thread, are comparing the vehicle cost to fuel cost, which is kinda cheating. It's not the cost of the fuel that matters, it's the cost of building the vehicle larger to hold that fuel -- and the fuel needed to launch that fuel -- that matters. So let's do the math!
Most data taken from http://spaceflight101.com/spac...
Basic info:
Stage 1: 23 tonnes structure, 400 tonnes fuel
Stage 2: 4 tonnes structure, 93 tonnes fuel
Payload: 13 tonnes
When launching, the first stage burns all 9 engines at full thrust for two and a half minutes. The re-entry burn and landing happen on a single engine, and from eyeballing the videos (including this one that shows the re-entry burn) appear to take about 30 seconds total. Assuming all burns are near full thrust (which is the best way to do it), that means the landing burn takes about (1/9) * (0:30 / 2:30) = 2% of the first stage fuel. Let's double that to 4% to provide a generous safety margin: that works out to about 400 * 0.04 = 16 tons more fuel.
This fuel is carried up to the moment that the second stage separates, so it subtracts from the mass of the second stage. Second stage plus payload weighs 110 tonnes: without the landing fuel, you could have scaled that up to 126 tonnes, a 15% increase.
So, landing the first stage reduces the payload SpaceX can launch, and thus the money they earn, by about 15%. In exchange, they recover about 75% of the cost of the launch hardware. So it's worth doing, even after you subtract off the cost of recovery and refurbishing. Maybe not the game-changer Elon Musk wants it to be, but it's a win.
If I had utterly failed to consider the possibility, I wouldn't have spent a couple sentences speculating on how it might be done. Could there be some revolution in optics I've never heard of? Sure, that's why I'm asking. Could a company have patented an idea they have no idea how to implement, so they can patent troll in the future? Well gosh, that never happens.
This has gotta be bullshit, or at least a conceptual patent (which is another word for bullshit), right?
From everything I know about optics -- and I teach college physics, so I'm not clueless -- if you put a video screen on the surface of the eyeball all you'll see is a colored blur over your whole field of vision. What matters is not the location of the light source on your cornea, but the *direction* it's coming from: any workable video screen would need to work kinda like a phased-array radar, but a million times smaller. Or something like the Lytro light field camera in reverse.
But while I can think of ways in which such a thing *could* work, with current technology this is utterly impossible. Anybody better-informed than me care to weigh in?
The risk of hurting the eagle really makes this a bad idea. If only there was some sort of machine that could do this job, like a robo-eagle? It'd have to be an agile remote-controlled flying machine which used a camera to send images back to the operator.
Sadly such a thing hasn't been invented yet.
Because a controlled experiment involving the actual Earth would mean telling a few billion people they have to keep their population, technology, and society constant for a century, and a) nobody's gonna agree to that, and b) if they did there wouldn't be an issue.
Just to pick the top story on that realclimatescience.com site: it's looking at NOAA's statement that 2015 had record *average* temperatures in the US, and is rebutting with data on the *frequency of hot days* in the US, which is an entirely different idea. Since greenhouse gases control the rate at which energy *leaves* the earth to cooling it down, you would predict it should warm the coolest days more than the warmest. Which is exactly what's happened. IPCC report finds, globally, a significant increase in night and winter temperatures, a statistically insignificant change in temperature of the hottest days.
The match between theoretical prediction, and basic physics is the best way to assess the truth. You'll notice that the denialists will try to poke holes in the standard global warming story, but very rarely will they show show that their revised data agrees with a physical theory. (In particular, if CO2 and water vapor concentrations are rising, why *doesn't* that cause global warming in their view? By everything we know about these gases, it should.)
[E] is not possible when the experiment is being carried out over centuries, with a civilization growing inside the test chamber.
[D] leads to biases (chiefly the urban heat island effect) which *increase* the apparent trend (see Layzej's reply). If you don't correct for them, global warming looks *worse* than it actually is.
Your point that most cemeteries are eventually reused is well taken, though Americans are very *very* resistant to that, probably because they can afford to be.
Agree, except that it's a non-renewable resource: once a cemetery, always a cemetery, and there's a social taboo against using them as public parks or letting them revert to nature. I first started thinking about this when my commute took me past some of the big cemeteries on the north side of Chicago. Square miles filled with the corpses of just one century's worth of Chicagoans. Give it another few centuries, and the dead will own more land than the living.
Let me break it down for you: I eat my weight in plants and animals about every six months or so. So the amount of biomass in my actual body is less than 1% of the biomass in the food I ate, and the inedible plant and animal parts I threw away. You can try to recycle your body if you want to, it's a nice gesture, but it's an insignificant part of the environmental problem.
(You're also wrong on the biochemistry, "useful proteins and specialized molecules" are not assembled over centuries and preserved through the food web. Plants build all their complex biomolecules from scratch; animals break the biomolecules in their food down into simple organics and reassemble them.)
Yes, cremation requires energy input: my point all along has been that that input is tiny compared to what a living human uses over any length of time: it amounts to a few kg of carbon. Your post doesn't counter that point.
Accumulated mercury doesn't go away during cremation, but people typically keep the cremains rather than dumping them back into their food supply, and crematoria are starting to take this issue seriously. And yes, all animals pose a drug and pathogen risk even now, which is why we typically render them rather than composting, and we take extra special care when recycling animal parts and waste back into the food supply. If you don't, you get e. coli infested vegetables, mad cow disease, etc.
In any case, my point was not that composting is definitely a serious threat, but that the potential risks aren't worth the tiny benefit.