Speaking of Science, which like I said is one of the top two science journals and even from U.S.:), has an editorial with the title The Scientific Consensus on Climate Change --- well worth reading.
The original Nature article about summer 2003 blame is reviewed here, reading the article itself requires a subscription either from you personally or from your institution. Possible speculation about juridical consequences is also there.
This was published in Nature, which is one of the two most prestigious science journals (the other one is Science). It is based on climate models that predict that the probability of heat waves like that of 2003 has doubled due to greenhouse gas emissions. (According to the same models, by 2050 about 50% of European summers are going to be like the 2003 or worse.)
If we suppose the probabilities from the models are correct, the attribution of part of blame to greenhouse gases is correct, just like one can claim some lung cancers are caused by tobacco.
I have already seen speculation about the possible use of the results in courts against the polluters.
What is interesting is that this is old news, about average CO2 during 2002 and 2003. The record high 2003 increase was reported already at the beginning of the year, and then there were news about record-high March announced by someone with access to the information in a conference.
Does anybody know the origin of the current news story? Was there a press release somewhere? Why just now? Because of the US election or because the trend has got more confirmation during the recent months?
(Yes, models are uncertain. No, warming is most likely not due to natural causes. CO2 increase is definitely mostly of human origin. Biosphere is very complex. We have played Russian roulette enough for now.)
The ozone and global warming should be separated.
Lightning will not patch the ozone hole, because surface ozone (lightning) is separate from the upper-level ozone protecting us from UV radiation. Surface ozone is actually a pollutant.
Increased vegetation is really thought to play a role in mitigating global warming. But the effect is not strong enough and not fast enough. Recent studies (summer 2004) also raise the possibility that increased CO2 will increase CO2 emissions from arctic beat bogs and from forests as well, due to the changes in microbe fauna in the soil.
The CO2 concentration measures (our point A) are not rocket science. Mauna Loa is a place with a particularly long time series of measurements available, and by searching for 'Mauna Loa CO2' you will find more than you want to know about this. Nobody (except for crackpots?) disagrees on recent CO2 concentrations and its trends. Atmospheric CO2 is increasing. And geological time series from ice cores etc. tell us that the current concentrations have not been seen for at least 100000 years, maybe for millions of years.
Warming effects of CO2 cannot be denied (our point B). The effect of CO2 is about radiation balance, and the absorption spectra of CO2, that is, basic physics. Mars has no greenhouse effect, Venus has a run-out greenhouse effect. Earth is somewhere between, with calculations indicating our temperature would be around -15 Celcius degrees without a greenhouse.
About (C), I think the pressure, at least the political pressure in US, is quite the contrary. Floods of money are available from industry-funded groups for those who would be able to disprove the CO2 connection. It just has not happened, and will not.
Simulating climate in the sense claimed in (D) is much easier than simulating weather. Think of weather as a microstate of a gas, and climate as the macrostate. Temperature and pressure are easy to predict, locations of individual particles not. That said, climate models are uncertain. There is both parametric uncertainty and uncertainty due to unknown nonlinear effects in the atmosphere, land, seas, and ecosystems.
But you do not need models to predict warming. Models are only required to predict the details (how much, where, what else happens).
In scientific circles, global warming has been around for decades, and even international conventions now exist to limit CO2. Global warming has become political because it fundamentally affects the interests of both industry and individual people.
In climate politics, your current federal administration is simply not up to its task. We just have to hope the next one will be.
(A) The earth has warmed about 0.5-0.6 Celsius degrees during the last few decades.
(B) Atmospheric CO2 has risen from 280ppm to about 380ppm since the beginning of the industrial age. The trend is +1.6ppm per year, and it is accelerating. CO2 is known to be a greenhouse gas from basic physics, and time series of prehistory confirm the relationship between temperature and CO2.
(C) Business as usual. Most of the science is sound.
(D) Yes, you are right that currently we cannot blame global warming on hurricanes. There is too little (hurricane) data, and the current warming is thought to be not enough to make a measurable difference. But this is going to change in future, for simulations indicate that warming and hurricanes are connected.
Ok, tropical sea surface temperatures are about +5 degrees over normal...
It has risen about 30%, from 280ppm to 380ppm. The current trend is up about 1.6ppm per year, and it is accelerating. You can find this everywhere in the web. Google for 'atmospheric CO2', for example.
Nature is putting CO2 into the atmosphere all the time, and also taking it away. It is all about balance - even now that we have managed to raise atmospheric CO2 by 30% (yes, 30%, up to 380ppm), oceans have taken half of all our excess CO2. We just have to hope they will do that in future as well, and that land ecosystems will stay neutral.
There is no question about the warming effects of CO2. A historical confirmation exists as the temperature-CO2 time series for the diehards not willing to believe basic physics. Recent studies, published in <em>Nature</em>, <em>Science</em>, and other prestigious journals have put the effects of sun under 10% on the current (30-year) warming.
Uncertainties remain however: 1) nobody quite knows how sensitive the atmosphere is to raising CO2; 2) nobody knows how much we are going to put CO2 to the atmosphere in future; 3) effects of CO2 may be highly nonlinear and abrupt due to various positive and negative feedback effects, which are and will be about impossible to estimate.
All this uncertainty, however, does not make me sleep better.
OK, I agree that one could get P300 out from ten or so responses with proper spatial and temporal filtering. I have been doing that kind of stuff myself (see the new special issue of Neuro-otol.&Audiology on MMN for an outline).
1 or 2 still sounds overoptimistic, and I fail to see any EEG technique with which one could extract meaningful P300 variation from a few responses only. 'Meaningful variation' means changes in P300 due to attentional effects. On the group level everything is possible, it's much harder with individuals (less data, individual variation).
MEG or optical imaging could help, but MEG is expensive (done that as well) and optical is still in its infancy (although very interesting - they measure phase changes in a modulated light loop going through the skull to the cortex and back, noninvasively - for some reason neural activity changes the phase). fMRI is even more cumbersome and expensive.
People have been measuring P300 for years - actually at least 20 years. Good luck if you try to get more than 0.1bit/sec output rate through it.
There were great hopes for P300 some years ago. People thought one can diagnose almost every neural disorder with it. The problem turned out to be that it correlates with _too many_ things. And it's noisy.
In general, one can't measure a single P300 wave. Instead, 100 or so "epochs" of data, each time locked to a stimulus, must be averaged to get a good signal. For information transmission even more is needed, because the wave is affected only slightly by attention (or everything else, for that matter).
There are more promising computer interfaces around, such as eye movement detection, or simply speech. Direct connection with a practical bit rate (in the information-theoretic sense) is just a day dream right now.
1. First, nobody really knows how the mind is "implemented", i.e., which parts of the structure of the brain are important.
There are synapses, but things also happen inside the cells. One would also need to know the laws that govern the development of the state of the brain at the functional level at which the system was extracted from the brain. Laws of physics are not enough for this unless you copy everything starting from the bottom. In other words, in order to simulate the brain, you need to know which physical processes are important and which are not. And we are very far off from this goal now (I have done brain research...despite all the hype, the state of the research is depressing, and the brain as a biological system is a complete mess).
The alternative would be to copy everything starting from the quantum level. But this is impossible: according to the rules of the quantum mechanics, the state of the brain is destroyed by measurements accurate enough. And still, measuring the whole state would not be possible (Heisenberg uncertainty principle: measure momentum, lose position etc.).
2. Second, if you are concerned about privacy, human rights and such things, would you really be willing to give total control of your mind to other people? I wouldn't. You won't even have your body! That's even worse than the current situation of Stephen Hawkings. How about if somebody finds it amusing to make you his enemy in Quake and facilitate your learning by making sure you really suffer when he shoots you...
3. The third problem is that the copy wouldn't necessarily be you, but another mind which starts as identical to yours (at the time of copying).
Here is a thought experiment:
Suppose it's possible to duplicate your body so that neither of the resulting persons is more original than the other one. You volunteer in an experiment, where you are anesthetized, then copied, and a red line is drawn to the palm of one of the copies. The question is: do you wake up with a red line in your hand or not? If you say that you don't know, where does the uncertainty come from? The physical process itself seems rather deterministic.
... and space is mostly empty anyway, so collisions in our neighbourhood would be extremely rare, and "all of our history of astronomy" is only less than 1/10^7:th part of the history of the universe.
Uncertainty in quantum mechanics is not related to extra dimensions. Uncertainty is something more fundamental, although it may have some relationship with the 'fabric' of space-time we don't know about yet.
The position of a particle along those extra dimensions is just a kind of state of the particle.. except that in quantum mechanics particles are waves, and the state is not about th e position (only) but about the frequency of the wave in the direction of those extra dimensions. Different vibrational states give rise to different kinds of particles.
(Or closely like that... this really goes below my knowledge.)
About those extra dimensions: they are curled up in the same sense as the surface of a tube is curled up. If you look at a long tube from a distance, you see only one dimension (which you would measure by 'length'). A closer look reveals another dimension with a different circle-like topology. The same thing can happen with 10 dimensions, 7 being microscopic - it's just harder to imagine and the number of possible ways to do it is very high.:)
This analogy helps, but mathematically you can describe the tube as a curved two-dimensional object without the third dimension. It is just easier to understand untuitively if you think it embedded into a third dimension.
Then you refer to orthogonality (being at right angles). It's a matter of parametrization, i.e. setting up the coordinate axes.
What I was trying to say: preprints come out every day, and curled dimensions is nothing new. What is the new thing in this paper compared to all other preprints?
Reading the abstract:) cleared things a bit. It's not about curled dimensions but about a few parallel universes which interact only through gravity.
For everybody interested in strings and stuff like this: read the book Elegant universe by Brian Greene. Another good one is Life of the cosmos by Lee Smolin (you may read the first part and forget the crap about black holes and evolution at the end if you feel so). Penrose's Emperor's New Mind has a similar structure: good review of modern physics at the beginning, hard-to-swallow personal views later.
Even the "ordinary" string theory has extra dimensions. They are just folded at a very small time scale (closer to 10^-40mm than 1mm). You can't use them for space or time travel any more than you can use the curled-up extra dimension of the water hose in your garden - it's still local even if it's an extra dimension.
What's the new thing with this brane theory? Is there more dimensions, or are the scales more macroscopic?
Slashdot Mirror
Speaking of Science, which like I said is one of the top two science journals and even from U.S. :), has an editorial with the title The Scientific Consensus on Climate Change --- well worth reading.
The original Nature article about summer 2003 blame is reviewed here, reading the article itself requires a subscription either from you personally or from your institution. Possible speculation about juridical consequences is also there.
This was published in Nature, which is one of the two most prestigious science journals (the other one is Science). It is based on climate models that predict that the probability of heat waves like that of 2003 has doubled due to greenhouse gas emissions. (According to the same models, by 2050 about 50% of European summers are going to be like the 2003 or worse.)
If we suppose the probabilities from the models are correct, the attribution of part of blame to greenhouse gases is correct, just like one can claim some lung cancers are caused by tobacco.
I have already seen speculation about the possible use of the results in courts against the polluters.
What is interesting is that this is old news, about average CO2 during 2002 and 2003. The record high 2003 increase was reported already at the beginning of the year, and then there were news about record-high March announced by someone with access to the information in a conference.
Does anybody know the origin of the current news story? Was there a press release somewhere? Why just now? Because of the US election or because the trend has got more confirmation during the recent months?
(Yes, models are uncertain. No, warming is most likely not due to natural causes. CO2 increase is definitely mostly of human origin. Biosphere is very complex. We have played Russian roulette enough for now.)
The ozone and global warming should be separated. Lightning will not patch the ozone hole, because surface ozone (lightning) is separate from the upper-level ozone protecting us from UV radiation. Surface ozone is actually a pollutant.
Increased vegetation is really thought to play a role in mitigating global warming. But the effect is not strong enough and not fast enough. Recent studies (summer 2004) also raise the possibility that increased CO2 will increase CO2 emissions from arctic beat bogs and from forests as well, due to the changes in microbe fauna in the soil.
More info on beat bogs and on carbon loss from forests. (More or less random links to the news articles that appeared everywhere.)
You should also be aware of some not so reliable information sources.
The CO2 concentration measures (our point A) are not rocket science. Mauna Loa is a place with a particularly long time series of measurements available, and by searching for 'Mauna Loa CO2' you will find more than you want to know about this. Nobody (except for crackpots?) disagrees on recent CO2 concentrations and its trends. Atmospheric CO2 is increasing. And geological time series from ice cores etc. tell us that the current concentrations have not been seen for at least 100000 years, maybe for millions of years.
Warming effects of CO2 cannot be denied (our point B). The effect of CO2 is about radiation balance, and the absorption spectra of CO2, that is, basic physics. Mars has no greenhouse effect, Venus has a run-out greenhouse effect. Earth is somewhere between, with calculations indicating our temperature would be around -15 Celcius degrees without a greenhouse.
About (C), I think the pressure, at least the political pressure in US, is quite the contrary. Floods of money are available from industry-funded groups for those who would be able to disprove the CO2 connection. It just has not happened, and will not.
Simulating climate in the sense claimed in (D) is much easier than simulating weather. Think of weather as a microstate of a gas, and climate as the macrostate. Temperature and pressure are easy to predict, locations of individual particles not.
That said, climate models are uncertain. There is both parametric uncertainty and uncertainty due to unknown nonlinear effects in the atmosphere, land, seas, and ecosystems.
But you do not need models to predict warming. Models are only required to predict the details (how much, where, what else happens).
In scientific circles, global warming has been around for decades, and even international conventions now exist to limit CO2. Global warming has become political because it fundamentally affects the interests of both industry and individual people.
In climate politics, your current federal administration is simply not up to its task. We just have to hope the next one will be.
(A) The earth has warmed about 0.5-0.6 Celsius degrees during the last few decades.
(B) Atmospheric CO2 has risen from 280ppm to about 380ppm since the beginning of the industrial age. The trend is +1.6ppm per year, and it is accelerating. CO2 is known to be a greenhouse gas from basic physics, and time series of prehistory confirm the relationship between temperature and CO2.
(C) Business as usual. Most of the science is sound.
(D) Yes, you are right that currently we cannot blame global warming on hurricanes. There is too little (hurricane) data, and the current warming is thought to be not enough to make a measurable difference. But this is going to change in future, for simulations indicate that warming and hurricanes are connected.
Ok, tropical sea surface temperatures are about +5 degrees over normal...
It has risen about 30%, from 280ppm to 380ppm.
The current trend is up about 1.6ppm per year, and
it is accelerating. You can find this everywhere in the web. Google for 'atmospheric CO2', for example.
Nature is putting CO2 into the atmosphere all the time, and also taking it away. It is all about balance - even now that we have managed to raise atmospheric CO2 by 30% (yes, 30%, up to 380ppm), oceans have taken half of all our excess CO2. We just have to hope they will do that in future as well, and that land ecosystems will stay neutral.
There is no question about the warming effects of CO2. A historical confirmation exists as the temperature-CO2 time series for the diehards not willing to believe basic physics. Recent studies, published in <em>Nature</em>, <em>Science</em>, and other prestigious journals have put the effects of sun under 10% on the current (30-year) warming.
Uncertainties remain however: 1) nobody quite knows how sensitive the atmosphere is to raising CO2; 2) nobody knows how much we are going to put CO2 to the atmosphere in future; 3) effects of CO2 may be highly nonlinear and abrupt due to various positive and negative feedback effects, which are and will be about impossible to estimate.
All this uncertainty, however, does not make me sleep better.
OK, I agree that one could get P300 out from ten or so responses with proper spatial and temporal filtering. I have been doing that kind of stuff myself (see the new special issue of Neuro-otol.&Audiology on MMN for an outline).
1 or 2 still sounds overoptimistic, and I fail to see any EEG technique with which one could extract meaningful P300 variation from a few responses only. 'Meaningful variation' means changes in P300 due to attentional effects. On the group level everything is possible, it's much harder with individuals (less data, individual variation).
MEG or optical imaging could help, but MEG is expensive (done that as well) and optical is still in its infancy (although very interesting - they measure phase changes in a modulated light loop going through the skull to the cortex and back, noninvasively - for some reason neural activity changes the phase). fMRI is even more cumbersome and expensive.
People have been measuring P300 for years - actually at least 20 years. Good luck if you try to get more than 0.1bit/sec output rate through it.
There were great hopes for P300 some years ago. People thought one can diagnose almost every neural disorder with it. The problem turned out to be that it correlates with _too many_ things. And it's noisy.
In general, one can't measure a single P300 wave. Instead, 100 or so "epochs" of data, each time locked to a stimulus, must be averaged to get a good signal. For information transmission even more is needed, because the wave is affected only slightly by attention (or everything else, for that matter).
There are more promising computer interfaces around, such as eye movement detection, or simply speech. Direct connection with a practical bit rate (in the information-theoretic sense) is just a day dream right now.
There are synapses, but things also happen inside the cells. One would also need to know the laws that govern the development of the state of the brain at the functional level at which the system was extracted from the brain. Laws of physics are not enough for this unless you copy everything starting from the bottom. In other words, in order to simulate the brain, you need to know which physical processes are important and which are not. And we are very far off from this goal now (I have done brain research...despite all the hype, the state of the research is depressing, and the brain as a biological system is a complete mess).
The alternative would be to copy everything starting from the quantum level. But this is impossible: according to the rules of the quantum mechanics, the state of the brain is destroyed by measurements accurate enough. And still, measuring the whole state would not be possible (Heisenberg uncertainty principle: measure momentum, lose position etc.).
2. Second, if you are concerned about privacy, human rights and such things, would you really be willing to give total control of your mind to other people? I wouldn't. You won't even have your body! That's even worse than the current situation of Stephen Hawkings. How about if somebody finds it amusing to make you his enemy in Quake and facilitate your learning by making sure you really suffer when he shoots you...
3. The third problem is that the copy wouldn't necessarily be you, but another mind which starts as identical to yours (at the time of copying).
Here is a thought experiment:
Suppose it's possible to duplicate your body so that neither of the resulting persons is more original than the other one. You volunteer in an experiment, where you are anesthetized, then copied, and a red line is drawn to the palm of one of the copies. The question is: do you wake up with a red line in your hand or not? If you say that you don't know, where does the uncertainty come from? The physical process itself seems rather deterministic.
The position of a particle along those extra dimensions is just a kind of state of the particle.. except that in quantum mechanics particles are waves, and the state is not about th e position (only) but about the frequency of the wave in the direction of those extra dimensions. Different vibrational states give rise to different kinds of particles.
(Or closely like that... this really goes below my knowledge.)
This analogy helps, but mathematically you can describe the tube as a curved two-dimensional object without the third dimension. It is just easier to understand untuitively if you think it embedded into a third dimension.
Then you refer to orthogonality (being at right angles). It's a matter of parametrization, i.e. setting up the coordinate axes.
Reading the abstract :) cleared things a bit. It's not about curled dimensions but about a few parallel universes which interact only through gravity.
For everybody interested in strings and stuff like this: read the book Elegant universe by Brian Greene. Another good one is Life of the cosmos by Lee Smolin (you may read the first part and forget the crap about black holes and evolution at the end if you feel so). Penrose's Emperor's New Mind has a similar structure: good review of modern physics at the beginning, hard-to-swallow personal views later.
What's the new thing with this brane theory? Is there more dimensions, or are the scales more macroscopic?