One fascinating experiment demonstrates the Einstein-de Haas effect. The electron spins are randomly oriented in a non-magetized cylinder of iron, say, so the total angular momentum is 0. Now turn on an external magnetic field to align all the spins (enclose the cylinder in a solenoid) and, since the iron's total angular momentum now has a preferred direction, the cylinder will *spin* in the opposite sense. An amazing demonstration of "macroscopic" quantum stuff.
Right --- like some farmers I knew. "Chance of rain is always 50%, every day. It either rains or it don't." Why do we make meteorology so complicated?:)
Making a weapon requires foresight into the possible effects they may have. I seriously doubt chimps have such cognitive skills.
You may be selling them (and other animals) short. My terrier tends to gulp down her treat bones quickly, and my lab-mix nibbles on his for a couple of hours, driving the terrier nuts. So the terrier creates a distraction, running and barking at the front door, to lure the lab away from his bone. As soon as he reaches the door, the terrier spins around, runs back to the lab's bone, and gobbles it up. Works every time. The lab just watches her eat it with his tail and ears down.
Any of you guys remember this one? I thought so fondly of it that I ordered two from EBay. One of the first graphing calculators from 1988, I still use it every day because of its small folding form factor. Why has no one else done a folding calculator? My favorite of all time.
Well, of course they're indistinguishable only if the emitted radiation is the same wavelength as the absorbed. If two are emitted, then they must have different energies than the original.
There's a little confusion on this. The bulk (cosmological) motion of the host galaxy away from us gives rise to an overall redshift in the spectrum, affecting all spectral lines emitted. It is true, generally, that older stars tend to be red as they expand into red giants, whereas young massive stars are blue. There are young, red stars also, but they contribute negligibly to the cumulative luminosity. So after correcting for the redshift, we can get some idea as to the type of stars in the cluster and the evolution of such stars by looking at their color.
Well, I was being a little flippant. In a medium, photons travel at c between interactions with the electrons in the medium, so the average speed of photons through a medium is weighted down by these "collisions". Since they're bosons and indistinguishable, there's really no way to tell one that has been absorbed and emitted from one that has had no interactions.
For galaxies out to about 100 million light years, we can use a well-known relation between the pulsations of bright stars and their luminosities to get a pretty accurate distance. Beyond that, the simplest measure is the cosmological redshift of the light. If the redshift is, say, 10%, then we use the Hubble relation (speed / Hubble constant = distance), where (speed = redshift * speed of light) to get an estimate. We can then independently calibrate this with Type 1a supernovae, which all go off with roughly the same brightness. This is only really useful for smaller redshifts and distances, since asking for the distance of an object with a significant redshift is sort of ambiguous. Do you mean how far is it "now"? How far away was it when it emitted the radiation? But the above is the simplest answer to your question.
That's the most ridiculous of all the ridiculous arguments you've made. Cosmology is more active than it has ever been in evaluating new data.
Indeed -- it's being called the "golden age" of cosmology. It was a little staid when I was studying it in grad school, but then came the COBE results, the preliminary high-redshift supernovae hints at acceleration, and then WMAP. What a remarkable and explosive 15 years.
I can't help thinking "why?". At some point, doesn't it make sense to stop spending Billions of dollars of taxpayer money on Big Bang research? How much does it benefit us to know what happened.3 seconds after the big bang vs. 3 seconds vs. 10 million years? I'd rather see all this money fund research into advanced propulsion systems, robotics, and solar power technologies that will help us explore the Universe, rather than just gaze at it with ever more powerful equipment.
Well, I *hope* it's just you. Just like I don't get what makes a cat do particular things from time to time, I don't get people who aren't fundamentally *curious*. Even stipulating that there may *never* be a single practical application or utility derived from cosmology, it speaks poorly for our species if we have the capability to probe our fundamental origins from our little speck in the cosmos but lack the effort. In all cases, when we probe the Universe with more precise instruments, we find mysteries that we not only cannot explain, but that we never before *imagined*. The subtlety and beauty of the Universe demands enough respect for it that we at least peer through the crack in the door.
I'm afraid you are totally wrong and have obviously never examined the data. The reverse is quite obviously true at the merest glance at the chart in question.
Yes, I've examined the data, and I don't think it's as clear as you think. It would be interesting to see a real statistical test applied instead of bald assertions. It's hard to pull out much conclusively when each *pixel* in the chart represents about 1,000 years. Rather, we should note that they are at least tightly correlated during all this time. Looking at data over smaller time periods, I've seen the lag in temperature with respect to CO2 that I alluded to earlier.
And you still think that models created using past data are valid?
Given the degree of correlation in the past, they may very well predict future correlation. In what other sense do they use past data?
Unfortunately, most of the people with your convictions mode people that disagree down. Look at my posting history - you will find well-reasoned (or at least rational) posts marked troll, etc. In the last global warming debate there was a mod war over my post - it was modded up about 7 times, and down about 6.
It is what it is. Posturing yourself as some kind of whiny perpetual victim is tiresome to read.
But surely I can just turn that around and say that you cannot prove that your method is long run cheaper. In your scenario, I can at least show short run cheaper and long run unknown - while you have short run more expensive, long run unknown.
The whole point behind scientific inquiry is to show that those two unknowns above are not of the same magnitude. The end result of science is to be able to ascribe probabilities of likelihood to various assertions about the natural world.
What metric is used in the insurance business? What metric is used for car safety? This is a political question, not a scientific one.
I agree, but the point is that they require different approaches to understanding potential outcomes. What we should *not* do is blindly start swinging for the pinata.
And this is the big one, NO! Science can tell you about processes, and other things. It can tell you nothing about value!
Now you're just niggling. Of course it's the *application* of scientific principles, reasoning, and results that helps evaluate between differing courses and outcomes.
In any case, worst case warming of 10 degrees is not going to require a lot of population movement. It may require a larger energy expenditure on air conditioning, though.
Is this intended as a serious statement? 10 degrees is an *enormous* shift. I don't know of many predictions that go even this far. With around 80% of the world's population susceptible to water levels rising even a few feet, this would be catastrophic by anyone's measure.
rom your point of view, what is the difference between effective and cheapest? From a standard economics point of view (another field of engineering, not science, IMO), the cheapest (well, least expensive all in) is always the best solution. Why is this not the case here?
I have two answers: one, the most obvious, is that an effective solution removes the need for further iteration and repair which may cost more over the long run. Related to this, you may argue that this is really what you mean by the "cheapest" solution --- the cheapest in the long run. I would not disagree with this on the surface, but it assumes that we know the *reasons* why other approaches will not be, in the long run, as cheap. This evaluation of the "whys" is something that you and other engineers would apparently like to avoid.
And the issue of "cheapest" is not obvious. What is the metric used to determine cost? Lives? Property? Dollars? Evaluating the impact of warming and migrating populations on these observable effects takes careful consideration and the application of scientific methods.
Aren't these the same climate scientist that said we were going to have a record hurricane season this year
Nope, different scientists. Hurricane predictions are issued by meteorologists. In fact, in the article you linked, the prediction was for fewer storms than last year, and there is no mention *anywhere* of global warming having anything to do with it. Climate scientists are not so concerned with year-to-year fluctuations in the population of severe storms. The strong hurricane season was predicted based on a number of indicators that have very little to do with the CO2 level in the atmosphere or long-term climactic trends. The lack of Atlantic storms this year is blamed on strong shearing winds off the African coast that disrupted many storms from forming. Not anything to do, one way or the other, with global warming. The Pacific hurricane season has been pretty active, but I don't know if it's any more or less so than expected. Climatologists do predict, though, that *generally* one might expect those storms that form to be stronger than when the planet is cooler.
Yeah, these guys may be the top of their field, but being on top of a bunch of people who don't know crap doesn't say much
Well, that's a pretty uncharitable remark, considering that these are thousands of pretty smart people who spend their professional careers researching this field, and you don't. I'd think you were *really* smart if there wasn't evidence to the contrary!
In my perspective, an engineer doesn't care why it works, only that it does work.
Yes, this is true in my experience as well (physicist).
Perhaps that is the problem with global warming - too many scientists, not enough engineers. Why do you guys care who caused it, man, sun, or butterflies flapping away? I don't really care what caused it - I want to know what the most likely effects are and the cheapest way to fix them.
Oh good lord, no. The willing ignorance of *reasons* and consequences is a root of the whole problem, both politically and industrially. It's even probable that the most *effective* ways of treating problems are not the cheapest.
To relate this directly to global warming, what about the failure of climate scientists to predict current atmospheric methane levels? Methane is an important greenhouse gas, and the fact that it apparently has a self-regulated maximum concentration far lower than anyone predicted would certainly change, possibly invalidate, a lot of the predictions made by models that did not include that fact.
Of course, the failure to predict something current does not invalidate future predictions. Sure, methane is an important greenhouse gas, but I'm not aware of any predictions that included it as a necessary and significant component of warming in the near future, nor any observations of a significant present abundance of methane. CO2 is enough.
This was a big miss - what about CO2, the boogeyman of the global warming crowd? What if there is a self-regulating aspect to it at some level? What we know from the historical record is that warming is always followed by CO2 - what if that is because there is a strong self-regulator built in that we do not know about?
I think you've got it backwards. Over the last million years, there has been a smooth correlation between CO2 and global temperatures, with the temperature lagging the CO2 somewhat. At no point had the concentration been higher than 300 ppm, but recently a sharp rise has taken the abundance out of this envelope to almost 400 ppm. And the global temperatures are responding in kind. What's the big miss? Sure, maybe there's a deus ex machina that will somehow reverse the current trend, but is this what you're counting on? In fact, we know of a mechanism that runs the other way --- warming oceans tend to release some of their dissolved CO2, making the problem worse. And an increase in water vapor is no good, as this is a greenhouse "gas" as well.
You can say that I don't know that CO2 self-regulates - but I am not the one extrapolating current trends a few centuries into the future. I really don't trust a science built on models when they 1) base the models on past data alone, and 2) are making predictions wildly divergent from past data.
It's not a "few centuries" that is the problem, it's the next few *decades*. And it should be alarming that *there is no past data* to mimic what we're seeing. We've burst outside of that envelope. Perhaps the predictions are wrong, but it's also possible that we're *underestimating* the climate's response. We should be cautious.
OK, all you weak minded mods can now mod me down for daring to challenge you to think for yourselves!
You should have the courage of your own convictions without a sniveling appeal to persecution. I wish people would stop writing this passively defensive crap.
I'll have to paraphrase, but it is kind of remarkable that the film was made. Jon Stewart tried to imagine pitching a movie with the gripping charisma of Al Gore combined with the drama and excitement of a scientific powerpoint presentation. It's hard to imagine many execs falling over themselves to write that check.
Of course, I'll probably rent it (along with "Who Killed the Electric Car") tonight for a uber-geek double feature.
Perhaps we're pushing this so hard is makework for all of people who have degrees (in this field)?
Surprisingly not. Most astronomers I rub elbows with are not too supportive of the Hubble program. Sure, the pictures and deep field stuff is nice, but with recent advances in adaptive optics, we can build enormous ground-based scopes for much less money that outperform Hubble. And Hubble has diverted hundreds of millions of dollars away from other projects. I'm not a zealot for either side, but the professional astronomical community is certainly not of one mind on this.
Slashdot Mirror
One fascinating experiment demonstrates the Einstein-de Haas effect. The electron spins are randomly oriented in a non-magetized cylinder of iron, say, so the total angular momentum is 0. Now turn on an external magnetic field to align all the spins (enclose the cylinder in a solenoid) and, since the iron's total angular momentum now has a preferred direction, the cylinder will *spin* in the opposite sense. An amazing demonstration of "macroscopic" quantum stuff.
His rule applies to PowerPoint presentations, which this ain't.
Me too! Hi!
Wait. Let me guess. You're an engineer.
Right --- like some farmers I knew. "Chance of rain is always 50%, every day. It either rains or it don't." Why do we make meteorology so complicated? :)
You may be selling them (and other animals) short. My terrier tends to gulp down her treat bones quickly, and my lab-mix nibbles on his for a couple of hours, driving the terrier nuts. So the terrier creates a distraction, running and barking at the front door, to lure the lab away from his bone. As soon as he reaches the door, the terrier spins around, runs back to the lab's bone, and gobbles it up. Works every time. The lab just watches her eat it with his tail and ears down.
Any of you guys remember this one? I thought so fondly of it that I ordered two from EBay. One of the first graphing calculators from 1988, I still use it every day because of its small folding form factor. Why has no one else done a folding calculator? My favorite of all time.
It's about 25,000-30,000 parsecs, which is close to 75,000-100,000 light years.
Well, of course they're indistinguishable only if the emitted radiation is the same wavelength as the absorbed. If two are emitted, then they must have different energies than the original.
There's a little confusion on this. The bulk (cosmological) motion of the host galaxy away from us gives rise to an overall redshift in the spectrum, affecting all spectral lines emitted. It is true, generally, that older stars tend to be red as they expand into red giants, whereas young massive stars are blue. There are young, red stars also, but they contribute negligibly to the cumulative luminosity. So after correcting for the redshift, we can get some idea as to the type of stars in the cluster and the evolution of such stars by looking at their color.
Sure, but those who know the word "Cepheid" probably also know what they're used for. Just thought it would rock to be a little descriptive.
Well, I was being a little flippant. In a medium, photons travel at c between interactions with the electrons in the medium, so the average speed of photons through a medium is weighted down by these "collisions". Since they're bosons and indistinguishable, there's really no way to tell one that has been absorbed and emitted from one that has had no interactions.
For galaxies out to about 100 million light years, we can use a well-known relation between the pulsations of bright stars and their luminosities to get a pretty accurate distance. Beyond that, the simplest measure is the cosmological redshift of the light. If the redshift is, say, 10%, then we use the Hubble relation (speed / Hubble constant = distance), where (speed = redshift * speed of light) to get an estimate. We can then independently calibrate this with Type 1a supernovae, which all go off with roughly the same brightness. This is only really useful for smaller redshifts and distances, since asking for the distance of an object with a significant redshift is sort of ambiguous. Do you mean how far is it "now"? How far away was it when it emitted the radiation? But the above is the simplest answer to your question.
Nope. If you travel at the speed of light, then nothing ever happens.
HOT! ROD! FLAMES!
Indeed -- it's being called the "golden age" of cosmology. It was a little staid when I was studying it in grad school, but then came the COBE results, the preliminary high-redshift supernovae hints at acceleration, and then WMAP. What a remarkable and explosive 15 years.
Well, I *hope* it's just you. Just like I don't get what makes a cat do particular things from time to time, I don't get people who aren't fundamentally *curious*. Even stipulating that there may *never* be a single practical application or utility derived from cosmology, it speaks poorly for our species if we have the capability to probe our fundamental origins from our little speck in the cosmos but lack the effort. In all cases, when we probe the Universe with more precise instruments, we find mysteries that we not only cannot explain, but that we never before *imagined*. The subtlety and beauty of the Universe demands enough respect for it that we at least peer through the crack in the door.
Yes, I've examined the data, and I don't think it's as clear as you think. It would be interesting to see a real statistical test applied instead of bald assertions. It's hard to pull out much conclusively when each *pixel* in the chart represents about 1,000 years. Rather, we should note that they are at least tightly correlated during all this time. Looking at data over smaller time periods, I've seen the lag in temperature with respect to CO2 that I alluded to earlier.
And you still think that models created using past data are valid?
Given the degree of correlation in the past, they may very well predict future correlation. In what other sense do they use past data?
Unfortunately, most of the people with your convictions mode people that disagree down. Look at my posting history - you will find well-reasoned (or at least rational) posts marked troll, etc. In the last global warming debate there was a mod war over my post - it was modded up about 7 times, and down about 6.
It is what it is. Posturing yourself as some kind of whiny perpetual victim is tiresome to read.
The whole point behind scientific inquiry is to show that those two unknowns above are not of the same magnitude. The end result of science is to be able to ascribe probabilities of likelihood to various assertions about the natural world.
What metric is used in the insurance business? What metric is used for car safety? This is a political question, not a scientific one.
I agree, but the point is that they require different approaches to understanding potential outcomes. What we should *not* do is blindly start swinging for the pinata.
And this is the big one, NO! Science can tell you about processes, and other things. It can tell you nothing about value!
Now you're just niggling. Of course it's the *application* of scientific principles, reasoning, and results that helps evaluate between differing courses and outcomes.
In any case, worst case warming of 10 degrees is not going to require a lot of population movement. It may require a larger energy expenditure on air conditioning, though.
Is this intended as a serious statement? 10 degrees is an *enormous* shift. I don't know of many predictions that go even this far. With around 80% of the world's population susceptible to water levels rising even a few feet, this would be catastrophic by anyone's measure.
I have two answers: one, the most obvious, is that an effective solution removes the need for further iteration and repair which may cost more over the long run. Related to this, you may argue that this is really what you mean by the "cheapest" solution --- the cheapest in the long run. I would not disagree with this on the surface, but it assumes that we know the *reasons* why other approaches will not be, in the long run, as cheap. This evaluation of the "whys" is something that you and other engineers would apparently like to avoid.
And the issue of "cheapest" is not obvious. What is the metric used to determine cost? Lives? Property? Dollars? Evaluating the impact of warming and migrating populations on these observable effects takes careful consideration and the application of scientific methods.
Nope, different scientists. Hurricane predictions are issued by meteorologists. In fact, in the article you linked, the prediction was for fewer storms than last year, and there is no mention *anywhere* of global warming having anything to do with it. Climate scientists are not so concerned with year-to-year fluctuations in the population of severe storms. The strong hurricane season was predicted based on a number of indicators that have very little to do with the CO2 level in the atmosphere or long-term climactic trends. The lack of Atlantic storms this year is blamed on strong shearing winds off the African coast that disrupted many storms from forming. Not anything to do, one way or the other, with global warming. The Pacific hurricane season has been pretty active, but I don't know if it's any more or less so than expected. Climatologists do predict, though, that *generally* one might expect those storms that form to be stronger than when the planet is cooler.
Yeah, these guys may be the top of their field, but being on top of a bunch of people who don't know crap doesn't say much
Well, that's a pretty uncharitable remark, considering that these are thousands of pretty smart people who spend their professional careers researching this field, and you don't. I'd think you were *really* smart if there wasn't evidence to the contrary!
Yes, this is true in my experience as well (physicist).
Perhaps that is the problem with global warming - too many scientists, not enough engineers. Why do you guys care who caused it, man, sun, or butterflies flapping away? I don't really care what caused it - I want to know what the most likely effects are and the cheapest way to fix them.
Oh good lord, no. The willing ignorance of *reasons* and consequences is a root of the whole problem, both politically and industrially. It's even probable that the most *effective* ways of treating problems are not the cheapest.
Of course, the failure to predict something current does not invalidate future predictions. Sure, methane is an important greenhouse gas, but I'm not aware of any predictions that included it as a necessary and significant component of warming in the near future, nor any observations of a significant present abundance of methane. CO2 is enough.
This was a big miss - what about CO2, the boogeyman of the global warming crowd? What if there is a self-regulating aspect to it at some level? What we know from the historical record is that warming is always followed by CO2 - what if that is because there is a strong self-regulator built in that we do not know about?
I think you've got it backwards. Over the last million years, there has been a smooth correlation between CO2 and global temperatures, with the temperature lagging the CO2 somewhat. At no point had the concentration been higher than 300 ppm, but recently a sharp rise has taken the abundance out of this envelope to almost 400 ppm. And the global temperatures are responding in kind. What's the big miss? Sure, maybe there's a deus ex machina that will somehow reverse the current trend, but is this what you're counting on? In fact, we know of a mechanism that runs the other way --- warming oceans tend to release some of their dissolved CO2, making the problem worse. And an increase in water vapor is no good, as this is a greenhouse "gas" as well.
You can say that I don't know that CO2 self-regulates - but I am not the one extrapolating current trends a few centuries into the future. I really don't trust a science built on models when they 1) base the models on past data alone, and 2) are making predictions wildly divergent from past data.
It's not a "few centuries" that is the problem, it's the next few *decades*. And it should be alarming that *there is no past data* to mimic what we're seeing. We've burst outside of that envelope. Perhaps the predictions are wrong, but it's also possible that we're *underestimating* the climate's response. We should be cautious.
OK, all you weak minded mods can now mod me down for daring to challenge you to think for yourselves!
You should have the courage of your own convictions without a sniveling appeal to persecution. I wish people would stop writing this passively defensive crap.
Of course, I'll probably rent it (along with "Who Killed the Electric Car") tonight for a uber-geek double feature.
Surprisingly not. Most astronomers I rub elbows with are not too supportive of the Hubble program. Sure, the pictures and deep field stuff is nice, but with recent advances in adaptive optics, we can build enormous ground-based scopes for much less money that outperform Hubble. And Hubble has diverted hundreds of millions of dollars away from other projects. I'm not a zealot for either side, but the professional astronomical community is certainly not of one mind on this.