You're correct that pair production requires a nucleus, but that's a much stronger condition than you imply. You see, if a photon decayed into a positron-electron pair, there wouldn't be any way to satisfy momentum conservation and energy conservation simultaneously. It *never* happens without an interaction with a third particle to allow for energy/momentum conservation.
Anyone who is concerned with a major shift in the earth's climate is a troll? Even if you disagree with their conclusions, isn't it better to err on the side of caution and at least listen rationally to what they have to say? I mean, if they *are* right, the future of the entire human race might be in jeopardy...
Quite frankly, your post itself seems like a right-wing troll to me. However, I'm going to respond to it in the most rational manner possible just in case someone impressionable reads your post and thinks "well, he might have a point."
Short answer: you don't have a point.
Long answer...
1: Show me ACCURATE 1 million year tempature records. Wait!! We only have 80 years of records
Wrong. We have ice cores from Antarctica with 400,000 years of temperature records *and* CO2 concentration measurements. The data is
chilling: the CO2 concentration is very well correlated with the temperature of the lower atmosphere over 400 millennia, and the CO2 concentration today (370 ppm) is higher than the maximum value in the last 400 millennia (300 ppm). Mind you, there have been numerous volcanic eruptions and major climate shifts (several ice ages, for instance) in that time period. Even considering those factors, the CO2 concentration is higher now than it has ever been in 400 millennia of recorded data.
Now, if you read that link carefully instead of just looking at the plots, you'll notice that they mention that 460 million years ago, CO2 levels were at 4400 ppm while the climat was roughly the same as it is today. That seems odd given that I'm claiming that there is a strong correlation between temperature and CO2 concentration (based on the fact that CO2 blocks infrared light but is transparent to visible light, thus trapping heat in the earth's atmosphere).
My answer to this conundrum is that we can only make projections on relatively short time scales. Correlating CO2 concentration and global temperatures over several hundred millennia is one thing; attempting to correlate them over timescales 1000x longer is quite another. For one thing the entire ecosystem of the earth was vastly different 460 million years ago: life was confined to the oceans. The sun may have had a lower radiative output than it does now, etc, etc.
2: Show me this hasnt happened before.
It doesn't seem to have happened at any point in the last 400,000 years.
Even if this kind of global warming *had* happened before, that's irrelevant. The point is that the earth's climate *does* shift naturally all the time. It doesn't shift by this much, of course (or at least the CO2 levels haven't been this high in the last 400,000 years), but it does change. The bottom line is: we couldn't survive a *natural* climate shift, let alone a bigger artificial climate shift. If global temperatures change by even a little bit, it will destabilize our civilization in frightening ways (which I describe below). If the climate shift is natural (which I don't believe it is) then we need to fight it to survive. If the climate shift is artificial, then we need to fight the industries that are causing it in order for humanity to survive.
3: Tell me the "scientists" studying arent also getting grants from... greenpeace or ELF..
Look at the links on the bottom of the page I already linked to. See all the references to Nature articles?
Lemme let you in on how the scientific debate process works. Scientists get grants from lots of different places. Honestly, I've never heard of anyone getting a grant from either Greenpeace or ELF (both of which are borderline terrorist organizations IMHO), but even if a scientist gets a grant from an organization you don't like, that is completely f*cking irrelevant! The research has to be s
Well, maybe what makes the weather models inaccurate is the grid size of the simulations. If you try to model a physical system with a finite-element type of approach and set the gridsize so large that it glosses over important dynamical processes, it won't be accurate.
But if you can decrease the grid size by throwing more teraflops at the problem, maybe we'll find that our models are accurate after all?
Slashdot Mirror
You're correct that pair production requires a nucleus, but that's a much stronger condition than you imply. You see, if a photon decayed into a positron-electron pair, there wouldn't be any way to satisfy momentum conservation and energy conservation simultaneously. It *never* happens without an interaction with a third particle to allow for energy/momentum conservation.
Anyone who is concerned with a major shift in the earth's climate is a troll? Even if you disagree with their conclusions, isn't it better to err on the side of caution and at least listen rationally to what they have to say? I mean, if they *are* right, the future of the entire human race might be in jeopardy...
Quite frankly, your post itself seems like a right-wing troll to me. However, I'm going to respond to it in the most rational manner possible just in case someone impressionable reads your post and thinks "well, he might have a point."
Short answer: you don't have a point.
Long answer...
1: Show me ACCURATE 1 million year tempature records. Wait!! We only have 80 years of records
Wrong. We have ice cores from Antarctica with 400,000 years of temperature records *and* CO2 concentration measurements. The data is chilling: the CO2 concentration is very well correlated with the temperature of the lower atmosphere over 400 millennia, and the CO2 concentration today (370 ppm) is higher than the maximum value in the last 400 millennia (300 ppm). Mind you, there have been numerous volcanic eruptions and major climate shifts (several ice ages, for instance) in that time period. Even considering those factors, the CO2 concentration is higher now than it has ever been in 400 millennia of recorded data.
Now, if you read that link carefully instead of just looking at the plots, you'll notice that they mention that 460 million years ago, CO2 levels were at 4400 ppm while the climat was roughly the same as it is today. That seems odd given that I'm claiming that there is a strong correlation between temperature and CO2 concentration (based on the fact that CO2 blocks infrared light but is transparent to visible light, thus trapping heat in the earth's atmosphere).
My answer to this conundrum is that we can only make projections on relatively short time scales. Correlating CO2 concentration and global temperatures over several hundred millennia is one thing; attempting to correlate them over timescales 1000x longer is quite another. For one thing the entire ecosystem of the earth was vastly different 460 million years ago: life was confined to the oceans. The sun may have had a lower radiative output than it does now, etc, etc.
2: Show me this hasnt happened before.
It doesn't seem to have happened at any point in the last 400,000 years.
Even if this kind of global warming *had* happened before, that's irrelevant. The point is that the earth's climate *does* shift naturally all the time. It doesn't shift by this much, of course (or at least the CO2 levels haven't been this high in the last 400,000 years), but it does change. The bottom line is: we couldn't survive a *natural* climate shift, let alone a bigger artificial climate shift. If global temperatures change by even a little bit, it will destabilize our civilization in frightening ways (which I describe below). If the climate shift is natural (which I don't believe it is) then we need to fight it to survive. If the climate shift is artificial, then we need to fight the industries that are causing it in order for humanity to survive.
3: Tell me the "scientists" studying arent also getting grants from... greenpeace or ELF..
Look at the links on the bottom of the page I already linked to. See all the references to Nature articles?
Lemme let you in on how the scientific debate process works. Scientists get grants from lots of different places. Honestly, I've never heard of anyone getting a grant from either Greenpeace or ELF (both of which are borderline terrorist organizations IMHO), but even if a scientist gets a grant from an organization you don't like, that is completely f*cking irrelevant! The research has to be s
But if you can decrease the grid size by throwing more teraflops at the problem, maybe we'll find that our models are accurate after all?