You aren't at all interested in knowing how common the Earth is? Whether the process that lead to the Earth orbiting the sun happens only rarely? What other planets are like? Do many (any?) of them have life, or something like it? If they do, what form does it take, is it like us? While Kepler won't answer all these questions, it's a small, but significant step in a long-term plan to address all of these questions. Even if we never are capable of ever going to any of these planets, I'd still like to know the answers to the above questions. And, as another poster mentioned, what better way to convince people to work on technology to travel to other stars than to find a specific destination to go to?
You're right regarding the importance of the atmosphere. In principle you could measure the atmospheric composition through transmission/emission spectroscopy at primary/secondary transit, however this is not feasible in the short term (maybe with 30m class telescopes it could be done). They'll have a hard enough time measuring the masses and securely confirming that any particular one of these things is planet (note the trouble with accurately determining the mass of Corot-Exo-7b for which the velocity semi-amplitude of the star is ~10 meters per second, whereas for the habitable Earth-size planets Kepler is looking for it's ~10 centimeters per second). But Kepler really isn't designed to tell us about particular habitable planets, rather it's designed as a census to figure out what fraction of stars have planets comparable to the size of the Earth orbiting at distances of an AU or so. Knowing that number will have a big influence on how we design future missions to find/study other planets that are really like the Earth (Earth-like climates).
Maybe I'm missing something, but why are they comparing the total number of convictions in two years (2008 and 2007) to the total number of convictions in 1 year (2005)? Isn't this more like a 145/40 = 3.6-fold increase in the conviction rate between 2008 and 2005 not a (145 + 100)/40 = 6.1-fold increase?
As others have said, if the planet has the same average density as the earth, then its surface gravity would be 1.7 times greater. It's interesting, however, to see what how the density/surface gravity depends on composition.
In this paper there are theoretical relations between planet radius and mass for a wide range of possible planet compositions. These are computed using equations of state that are largely determined from laboratory experiments.
Anyway, for an Earth-like composition (~67% rock, 33% iron), a 5 M_earth planet would have a radius of ~1.5 R_earth yielding a surface gravity that is ~2.2 times greater than that of the Earth (such a planet is not incompressible, so the density is slightly higher for a greater mass).
For a pure iron planet, the radius would be only 1.2 times that of the Earth and the surface gravity would be quite high (3.6 times the Earth's).
For a pure rock planet, the radius would be 1.7 times that of the Earth and the surface gravity would be 1.75 times that of the Earth.
For a pure "water-world" (say a scaled up version of some of the icy satellites orbiting the outer planets), the radius would be ~2.5 times that of the Earth and the surface gravity would be 0.8 times that of the Earth (i.e. less surface gravity than the Earth!).
Point is there is a fairly significant range in possible radii and thus a significant range in the possible surface gravity.
Like many scientific imagers, the camera on phoenix (called the surface stereo imager http://fawkes3.lpl.arizona.edu/science_ssi.php ) uses a filter wheel in front of a CCD. They have 12 filters picked specifically for geological and atmospheric interest. Presumably three of the filters roughly correspond to red, green and blue, so they can take an image through each filter and then composite them into a single color image. I assume they've just been posting the raw images taken through a given filter first and will composite them once they've got a set in. Note that your digital camera works in a similar way (takes images through three filters and composites them, it may place a permanent color filter array in front of the CCD, or use three separate CCDs and a beam splitter rather than using a spinning filter wheel), except it does the compositing automatically. Since the imager on phoenix will not be used exclusively for making RGB color images, there's no reason to have the camera automatically take images through those three filters and do the compositing.
Also, it looks like many of the images they've taken first are of the solar arrays - I imagine they wanted to take quick single filter images of each array and send them back first over their limited bandwidth to see that they really deployed, before taking and transmitting a color panorama.
I agree that it's not clear that this GRB will be that significant of an outlier after a decade or so of observations. Three of the four intrinsically brightest events ever observed occurred in the last 3 years and were discovered by Swift (050904, 061007 and 080319B which is this one). This one is also not an order of magnitude brighter (intrinsically) than any other GRB - more like a factor of 2 (the next brightest was 050904 which in turn was a factor of ~2 brighter than the third most luminous GRB, see figure 4 in http://arxiv.org/abs/0803.3215 ). Certainly it's a really cool event, neat to think that you could have seen something 7 billion light years away with the naked eye, but I'd be surprised if we don't see even more luminous ones in the next few decades.
i got choked up myself just now reading the last sentence of the article:
"In an interview with The Associated Press, Clarke said he did not regret never having followed his novels into space, adding that he had arranged to have DNA from strands of his hair sent into orbit. 'One day, some super civilization may encounter this relic from the vanished species and I may exist in another time,' he told AP.
Along with his DNA sample, Clarke enclosed a note with a brief handwritten wish addressed to that far-flung future: 'Fare well, my clone.'"
Indeed.
"Childhood's End" is one of the most moving stories I have ever read, nor will I ever forget the excitement and suspense of the first entry into Rama. He brought such an amazing degree of realism to his fiction. More than any writer I know of, he could make the reader feel like they were actually living in the future.
I am so sad to hear that he is gone.
I for one would love not having to get out of the car to pump gas when it's 10 degrees out, and would easily pay 10 cents per gallon more for the convenience. Obviously you can achieve the same thing with a human attendant, but they tend to be fairly slow in my experience when there are several cars for them to pump simultaneously. Given a choice between a station with human attendants and robot attendants I would pick the robots if they were faster and didn't carry additional risks of damaging my car. Assuming ~1000 cars per day filling up 15 gallons each, and 4 machines with negligible operating costs, they'd need to raise the price per gallon by 7 cents to make up the $400,000 investment in one year, after that it could act as a profit center. It would also be true that people might be more likely to go inside and buy items in the convenience store if they don't have to stand around by the pump, so it could be that they would recover the cost without necessarily raising the gas prices by that much. (I don't know why, but here in MA they never seem to put latches on the gas pumps, so you have to stand there holding the stupid thing to pump up your car when you could be inside buying a drink and some chips).
I don't know the reasons why hst uses an encrypted data stream, but it is in line with their policy regarding the public release of data. The principal investigator for the observations has a 1 year proprietary period on the data. This is because it represents a lot of work to plan in detail how the observations should be carried out and to justify the observations to the time allocation committee - so if you do the work of figuring out how the observations are to be done and why they should be done, you get a one year head-start on analyzing the data. After the one year period is up, the raw data is released to the public - anyone else can access it at http://archive.stsci.edu/
Perhaps, in that case they must have started wearing clothes at least three million years ago, whereas other lice evidence suggests that humans began wearing clothes 70000 years ago (e.g. http://www.headlice.org/news/2003/louseorigins.htm ).
I've also seen the suggestion that the loss of hair was generally a by-product of selection for neoteny (baby chimps are relatively hairless), which itself was selected for because it meant humans would keep learning into adulthood.
From the article: "And then there is the matter of where the lice live. Today, lice live on little islands of hair on an ocean of hairless human skin. They are clearly adapted to our relatively hairless bodies. The authors suggest that their results may mean that hominids were already losing hair 3.3 million years ago. The gorilla lice needed an empty ecological niche--pubic hair--that they could occupy in order to survive. If hominids had full-body hair, the lice that already lived on it might have been able to outcompete an invader."
In my opinion this is one of the most interesting aspects of this research - being able to date when we started becoming hairless. It's always been a puzzle why we are relatively hairless compared to the other great apes, and I would guess that being able to put some time constraints on it is a step toward understanding how this happened.
Re:This is an inference -- not a prediction
on
New Ice Age Theory
·
· Score: 3, Informative
I guess it's a bit of a symantics issue, whether it's a prediction or a post-diction. It's true that this "prediction" was made after the cycles themselves were observed in the temperature. However, the theory itself makes no reference to these observations, that is it doesn't use them for calibration (it's calibrated with observations of the sun only). The theory, instead, is that there is an oscillation in brightness that should be present in the Sun and other stars that hasn't been considered before. Ehrlich calculates the frequencies of the oscillation for the Sun (using only the solar model which is calibrated to observations of the sun without any reference to the paleotemperature record) and lo-and-behold the n=2,3 and 4 modes lie right on top of the three broad peaks in the fourier amplitude spectrum of the paleotemperature record. I don't think he can say exactly what the amplitude of the oscillation would be (a typical problem with modeling variable stars), though he does demonstrate that the oscillation would grow in time (i.e. it's unstable). The fact that the periods of this variation line up with the periods in the Earth's temperature is, at the very least, quite striking. In a sense, the periods could easily have been predicted by this theory before they were observed. If you're interested, you can see a pre-print for his article at http://xxx.lanl.gov/abs/astro-ph/0701117
I am much happier thinking that astronomers are in a hole somewhere in the middle of the night staring into the sky adding to the human body of knowledge, then sitting in a giant auditorium fighting over meaningless bullshit and operating at the lowest forms of the intellectual discourse
I agree with you. I think that most astronomers (at least all the ones I know) don't give a damn about what the definition of "planet" is - it really is not a pressing issue. The fact that so few people stuck around for the vote (as noted by the summary) shows this.
Actually they need to use small telescopes for this kind of project simply because large telescopes won't work. Only 1% of Sun-like stars will have a Jupiter-sized planet orbiting with a period less than ~10 days, and only 10% of these will transit from our point of view. So they need to look at ~1000 sun-like stars to have a chance of getting a single transiting hot jupiter. They're particularly interesting in finding these planets around bright stars since then you can hope to do interesting follow-up like measuring their atmospheres and reflected light. The point is, that to have any chance of finding such a planet around a bright star they need to look at very large fields of view - typically for these kind of surveys a single image will be 5 to 10 degrees on a side (which is 10 to 20 times the diameter of the full moon). It's incredibly difficult to get a very large field of view with a big telescope (for a 6 meter telescope the largest field of view camera that has been built covers half a degree by half a degree), so for this type of project small, cheap, off-the-wall telescopes are the best tools for the job. There are, in fact, a number of similar surveys using small telescopes to look for these things, and a planet (Tres-1) has already been found this way.
I find these sorts of conclusions, based solely on anecdotal evidence (individual conversations with professors) highly unconvincing. If anyone wants to know the answer they should do a real survey of high school curricula now vs. 10-20 years ago, or perhaps a survey of alumni who majored in these "hard sciences" vs. current majors. But as it is, I think individuals who did program and whose friends program will conclude that "yes kids program" and individuals who didn't, or who didn't have many friends who programmed, will conclude that "no kids don't program." There's almost nothing to be learned from that.
For as much as we want to call Man an animal (subject to an animal's exigencies and vicissitudes) we must admit that he is a curious sort of animal able to escape those forms of nature and create new configurations of need and choice.
I can't imagine that there's anyone who wouldn't agree that a human is a rather unique animal (among the set of animals that we are aware of). But I think the view that we are, nonetheless, animals is really quite interesting and useful. I find it fascinating when I learn how various human behaviours have been driven by natural selection. When I watch an ape or a chimp behave in a way that is just so eerily human, I realize that we really are connected to nature and how much we can learn about ourselves by studying other species. And, I think it creates a proper sense of place to realize that since we are the products of natural processes it's not hard to imagine that there could be creatures somewhere that might be far smarter than us or more amazing than us in some way we couldn't even fathom. To me the view that we are in any way separate from nature is confining - it limits peoples' imagination of the variety that nature may have produced, and it discourages attemps to improve upon the basic human design (e.g. genetic engineering or mechanical enhancements) and investigations into the natural processes that have created us and determine our behaviour.
I don't know if you were implying that we shouldn't view ourselves as animals. I just thought I'd take this opportunity to rant.
\end{rant}
I know, I can't believe it's so hard to find cadbury eggs around easter! This is the second year in a row that I haven't been able to find a single one for my wife after going to several stores.
Not everything has a "cause" per se. For example a radioactive nucleus will decay in a completely random fashion, you can't predict when it will happen at all... it just happens, and only after you observe the decay can you say that it happened. You can determine a probability that the particle will decay in a given amount of time... but you can't predict exactly when it will decay so far as we know. Someone might say "well just because we can't predict it now doesn't mean there isn't a cause for it to decay at the moment it does...and maybe someday someone will come along and figure out how to predict when it will decay" - it doesn't really matter since the point is that it could well be that there is no way to predict it...and never will be a way to predict it...and logic wouldn't fail. Nature can be however it wants to be... There doesn't need to be a further simplification to observed processes that we can point to as explanations... That's ultimately why we have to approach these problems observationally - Cosmology could have been anything....no one would have guessed the big bang before it was discovered that the universe is expanding...or inflation before it was discovered that the cosmic microwave background is incredibly smooth on large angular scales... but given the observations that have been made over the last century it seems that the inflationary/big bang model works for describing nature as we observe. Ultimately it doesn't matter if there was a "cause" to the inflation in the first place... absent any observations to constrain the period before inflation we can't tell... It could be that there was a giant spaghetti monster that dreamed it all up... or it could be a very human-like "god" that knows everything and is everywhere and gets jealous and cares a lot about a group of people that lived on the inner part of the mediterranean 4000 years ago that did... or it could be that there are infinite universes that all pop up each with a different set of laws and we live in one with laws as they are because those laws make things like us... or it could be that time itself is more akin to a spatial dimension which doesn't extend infinitely in that direction (like a sphere) so there isn't really a beginning or end but we perceive a flow to time via entropy.... or it could just be that there was nothing and then there was something, I don't see how that is completely unimaginable... or it could be that our minds simply can't fathom what happened like a flatworm can't fathom that it's a flatworm.
He's basing this conclusion on a model that suggests that the peak production in oil will occur when we have used half of the world's oil, so he doesn't need to actually see the oil production drop off to conclude that we've reached the peak, he only needs to know when we've used half of all the world's oil. The estimate for how much oil has been produced so far seems pretty solid. The estimate for how much oil there is available seems questionable. Unfortunately it seems that you have to buy his book to really see what his method is for estimating this and decide whether or not it's reasonable. There are plenty of sites that discuss how to estimate this number, including some referenced on the wikepedia peak oil site, though I don't have a good sense for which estimates seem the most reasonable.
This is a really neat demonstration of the power of microlensing for planet finding. Though it's not the first, nor even the second, planet to be found this way (see for example http://xxx.lanl.gov/abs/astro-ph/0505451 and http://xxx.lanl.gov/abs/astro-ph/0505451), it really does show how microlensing can find small planets pretty far away from their host stars. It'll be a very good technique for determining the frequency of planets as small as the Earth.
As for finding life on the microlensing discovered planets (using the future Terrestrial Planet Finder mission [http://planetquest.jpl.nasa.gov/TPF/tpf_index.cfm] for example to search for biosignatures in their spectra), it'll be very difficult. The majority of these planets are going to be very far away from us (where there is the highest probability of finding a lens) and, by selection, they're going to have a second bright star very close by on the sky that will be difficult to coronagraph out. The microlensing planets are really all going to be one-shot deals where you have no hope of following them up in the foreseeable future. I think planets found by transits (the upcoming Kepler mission [http://kepler.nasa.gov/]) or by astrometry (the upcoming Space Interferometry Mission [http://sim.jpl.nasa.gov/]) will be much better bets for searching for life.
This is actually a pretty exciting result that's different from the case of SN 1987A in that they're seeing light from ancient SN which were never observed originally. It's the idea of discovering ancient supernovae by light echoes that's new, not just seeing a light echo from a supernova. You can see their paper at http://xxx.lanl.gov/abs/astro-ph/0510738.
Slashdot Mirror
You aren't at all interested in knowing how common the Earth is? Whether the process that lead to the Earth orbiting the sun happens only rarely? What other planets are like? Do many (any?) of them have life, or something like it? If they do, what form does it take, is it like us? While Kepler won't answer all these questions, it's a small, but significant step in a long-term plan to address all of these questions. Even if we never are capable of ever going to any of these planets, I'd still like to know the answers to the above questions. And, as another poster mentioned, what better way to convince people to work on technology to travel to other stars than to find a specific destination to go to?
You're right regarding the importance of the atmosphere. In principle you could measure the atmospheric composition through transmission/emission spectroscopy at primary/secondary transit, however this is not feasible in the short term (maybe with 30m class telescopes it could be done). They'll have a hard enough time measuring the masses and securely confirming that any particular one of these things is planet (note the trouble with accurately determining the mass of Corot-Exo-7b for which the velocity semi-amplitude of the star is ~10 meters per second, whereas for the habitable Earth-size planets Kepler is looking for it's ~10 centimeters per second). But Kepler really isn't designed to tell us about particular habitable planets, rather it's designed as a census to figure out what fraction of stars have planets comparable to the size of the Earth orbiting at distances of an AU or so. Knowing that number will have a big influence on how we design future missions to find/study other planets that are really like the Earth (Earth-like climates).
Maybe I'm missing something, but why are they comparing the total number of convictions in two years (2008 and 2007) to the total number of convictions in 1 year (2005)? Isn't this more like a 145/40 = 3.6-fold increase in the conviction rate between 2008 and 2005 not a (145 + 100)/40 = 6.1-fold increase?
In this paper there are theoretical relations between planet radius and mass for a wide range of possible planet compositions. These are computed using equations of state that are largely determined from laboratory experiments.
Anyway, for an Earth-like composition (~67% rock, 33% iron), a 5 M_earth planet would have a radius of ~1.5 R_earth yielding a surface gravity that is ~2.2 times greater than that of the Earth (such a planet is not incompressible, so the density is slightly higher for a greater mass).
For a pure iron planet, the radius would be only 1.2 times that of the Earth and the surface gravity would be quite high (3.6 times the Earth's).
For a pure rock planet, the radius would be 1.7 times that of the Earth and the surface gravity would be 1.75 times that of the Earth.
For a pure "water-world" (say a scaled up version of some of the icy satellites orbiting the outer planets), the radius would be ~2.5 times that of the Earth and the surface gravity would be 0.8 times that of the Earth (i.e. less surface gravity than the Earth!).
Point is there is a fairly significant range in possible radii and thus a significant range in the possible surface gravity.
Like many scientific imagers, the camera on phoenix (called the surface stereo imager http://fawkes3.lpl.arizona.edu/science_ssi.php ) uses a filter wheel in front of a CCD. They have 12 filters picked specifically for geological and atmospheric interest. Presumably three of the filters roughly correspond to red, green and blue, so they can take an image through each filter and then composite them into a single color image. I assume they've just been posting the raw images taken through a given filter first and will composite them once they've got a set in. Note that your digital camera works in a similar way (takes images through three filters and composites them, it may place a permanent color filter array in front of the CCD, or use three separate CCDs and a beam splitter rather than using a spinning filter wheel), except it does the compositing automatically. Since the imager on phoenix will not be used exclusively for making RGB color images, there's no reason to have the camera automatically take images through those three filters and do the compositing. Also, it looks like many of the images they've taken first are of the solar arrays - I imagine they wanted to take quick single filter images of each array and send them back first over their limited bandwidth to see that they really deployed, before taking and transmitting a color panorama.
I agree that it's not clear that this GRB will be that significant of an outlier after a decade or so of observations. Three of the four intrinsically brightest events ever observed occurred in the last 3 years and were discovered by Swift (050904, 061007 and 080319B which is this one). This one is also not an order of magnitude brighter (intrinsically) than any other GRB - more like a factor of 2 (the next brightest was 050904 which in turn was a factor of ~2 brighter than the third most luminous GRB, see figure 4 in http://arxiv.org/abs/0803.3215 ). Certainly it's a really cool event, neat to think that you could have seen something 7 billion light years away with the naked eye, but I'd be surprised if we don't see even more luminous ones in the next few decades.
i got choked up myself just now reading the last sentence of the article: "In an interview with The Associated Press, Clarke said he did not regret never having followed his novels into space, adding that he had arranged to have DNA from strands of his hair sent into orbit. 'One day, some super civilization may encounter this relic from the vanished species and I may exist in another time,' he told AP. Along with his DNA sample, Clarke enclosed a note with a brief handwritten wish addressed to that far-flung future: 'Fare well, my clone.'"
Indeed. "Childhood's End" is one of the most moving stories I have ever read, nor will I ever forget the excitement and suspense of the first entry into Rama. He brought such an amazing degree of realism to his fiction. More than any writer I know of, he could make the reader feel like they were actually living in the future. I am so sad to hear that he is gone.
I for one would love not having to get out of the car to pump gas when it's 10 degrees out, and would easily pay 10 cents per gallon more for the convenience. Obviously you can achieve the same thing with a human attendant, but they tend to be fairly slow in my experience when there are several cars for them to pump simultaneously. Given a choice between a station with human attendants and robot attendants I would pick the robots if they were faster and didn't carry additional risks of damaging my car. Assuming ~1000 cars per day filling up 15 gallons each, and 4 machines with negligible operating costs, they'd need to raise the price per gallon by 7 cents to make up the $400,000 investment in one year, after that it could act as a profit center. It would also be true that people might be more likely to go inside and buy items in the convenience store if they don't have to stand around by the pump, so it could be that they would recover the cost without necessarily raising the gas prices by that much. (I don't know why, but here in MA they never seem to put latches on the gas pumps, so you have to stand there holding the stupid thing to pump up your car when you could be inside buying a drink and some chips).
I don't know the reasons why hst uses an encrypted data stream, but it is in line with their policy regarding the public release of data. The principal investigator for the observations has a 1 year proprietary period on the data. This is because it represents a lot of work to plan in detail how the observations should be carried out and to justify the observations to the time allocation committee - so if you do the work of figuring out how the observations are to be done and why they should be done, you get a one year head-start on analyzing the data. After the one year period is up, the raw data is released to the public - anyone else can access it at http://archive.stsci.edu/
Perhaps, in that case they must have started wearing clothes at least three million years ago, whereas other lice evidence suggests that humans began wearing clothes 70000 years ago (e.g. http://www.headlice.org/news/2003/louseorigins.htm ).
I've also seen the suggestion that the loss of hair was generally a by-product of selection for neoteny (baby chimps are relatively hairless), which itself was selected for because it meant humans would keep learning into adulthood.
From the article: "And then there is the matter of where the lice live. Today, lice live on little islands of hair on an ocean of hairless human skin. They are clearly adapted to our relatively hairless bodies. The authors suggest that their results may mean that hominids were already losing hair 3.3 million years ago. The gorilla lice needed an empty ecological niche--pubic hair--that they could occupy in order to survive. If hominids had full-body hair, the lice that already lived on it might have been able to outcompete an invader."
In my opinion this is one of the most interesting aspects of this research - being able to date when we started becoming hairless. It's always been a puzzle why we are relatively hairless compared to the other great apes, and I would guess that being able to put some time constraints on it is a step toward understanding how this happened.
I guess it's a bit of a symantics issue, whether it's a prediction or a post-diction. It's true that this "prediction" was made after the cycles themselves were observed in the temperature. However, the theory itself makes no reference to these observations, that is it doesn't use them for calibration (it's calibrated with observations of the sun only). The theory, instead, is that there is an oscillation in brightness that should be present in the Sun and other stars that hasn't been considered before. Ehrlich calculates the frequencies of the oscillation for the Sun (using only the solar model which is calibrated to observations of the sun without any reference to the paleotemperature record) and lo-and-behold the n=2,3 and 4 modes lie right on top of the three broad peaks in the fourier amplitude spectrum of the paleotemperature record. I don't think he can say exactly what the amplitude of the oscillation would be (a typical problem with modeling variable stars), though he does demonstrate that the oscillation would grow in time (i.e. it's unstable). The fact that the periods of this variation line up with the periods in the Earth's temperature is, at the very least, quite striking. In a sense, the periods could easily have been predicted by this theory before they were observed. If you're interested, you can see a pre-print for his article at http://xxx.lanl.gov/abs/astro-ph/0701117
I'm an astronomy grad student, so I know a lot of them actually.
I agree with you. I think that most astronomers (at least all the ones I know) don't give a damn about what the definition of "planet" is - it really is not a pressing issue. The fact that so few people stuck around for the vote (as noted by the summary) shows this.
Actually they need to use small telescopes for this kind of project simply because large telescopes won't work. Only 1% of Sun-like stars will have a Jupiter-sized planet orbiting with a period less than ~10 days, and only 10% of these will transit from our point of view. So they need to look at ~1000 sun-like stars to have a chance of getting a single transiting hot jupiter. They're particularly interesting in finding these planets around bright stars since then you can hope to do interesting follow-up like measuring their atmospheres and reflected light. The point is, that to have any chance of finding such a planet around a bright star they need to look at very large fields of view - typically for these kind of surveys a single image will be 5 to 10 degrees on a side (which is 10 to 20 times the diameter of the full moon). It's incredibly difficult to get a very large field of view with a big telescope (for a 6 meter telescope the largest field of view camera that has been built covers half a degree by half a degree), so for this type of project small, cheap, off-the-wall telescopes are the best tools for the job. There are, in fact, a number of similar surveys using small telescopes to look for these things, and a planet (Tres-1) has already been found this way.
I find these sorts of conclusions, based solely on anecdotal evidence (individual conversations with professors) highly unconvincing. If anyone wants to know the answer they should do a real survey of high school curricula now vs. 10-20 years ago, or perhaps a survey of alumni who majored in these "hard sciences" vs. current majors. But as it is, I think individuals who did program and whose friends program will conclude that "yes kids program" and individuals who didn't, or who didn't have many friends who programmed, will conclude that "no kids don't program." There's almost nothing to be learned from that.
I can't imagine that there's anyone who wouldn't agree that a human is a rather unique animal (among the set of animals that we are aware of). But I think the view that we are, nonetheless, animals is really quite interesting and useful. I find it fascinating when I learn how various human behaviours have been driven by natural selection. When I watch an ape or a chimp behave in a way that is just so eerily human, I realize that we really are connected to nature and how much we can learn about ourselves by studying other species. And, I think it creates a proper sense of place to realize that since we are the products of natural processes it's not hard to imagine that there could be creatures somewhere that might be far smarter than us or more amazing than us in some way we couldn't even fathom. To me the view that we are in any way separate from nature is confining - it limits peoples' imagination of the variety that nature may have produced, and it discourages attemps to improve upon the basic human design (e.g. genetic engineering or mechanical enhancements) and investigations into the natural processes that have created us and determine our behaviour.
I don't know if you were implying that we shouldn't view ourselves as animals. I just thought I'd take this opportunity to rant. \end{rant}
Actually I regularly use ~10 Gb for storing simple ascii text files.
And roughly 8 Tb for storing images (although granted, not in jpg format).
Anyway, your point is well taken. And frankly, 750 Gb already is a pittance from my point of view.
I know, I can't believe it's so hard to find cadbury eggs around easter! This is the second year in a row that I haven't been able to find a single one for my wife after going to several stores.
Not everything has a "cause" per se. For example a radioactive nucleus will decay in a completely random fashion, you can't predict when it will happen at all... it just happens, and only after you observe the decay can you say that it happened. You can determine a probability that the particle will decay in a given amount of time... but you can't predict exactly when it will decay so far as we know. Someone might say "well just because we can't predict it now doesn't mean there isn't a cause for it to decay at the moment it does...and maybe someday someone will come along and figure out how to predict when it will decay" - it doesn't really matter since the point is that it could well be that there is no way to predict it...and never will be a way to predict it...and logic wouldn't fail. Nature can be however it wants to be... There doesn't need to be a further simplification to observed processes that we can point to as explanations... That's ultimately why we have to approach these problems observationally - Cosmology could have been anything....no one would have guessed the big bang before it was discovered that the universe is expanding...or inflation before it was discovered that the cosmic microwave background is incredibly smooth on large angular scales... but given the observations that have been made over the last century it seems that the inflationary/big bang model works for describing nature as we observe. Ultimately it doesn't matter if there was a "cause" to the inflation in the first place... absent any observations to constrain the period before inflation we can't tell... It could be that there was a giant spaghetti monster that dreamed it all up... or it could be a very human-like "god" that knows everything and is everywhere and gets jealous and cares a lot about a group of people that lived on the inner part of the mediterranean 4000 years ago that did... or it could be that there are infinite universes that all pop up each with a different set of laws and we live in one with laws as they are because those laws make things like us... or it could be that time itself is more akin to a spatial dimension which doesn't extend infinitely in that direction (like a sphere) so there isn't really a beginning or end but we perceive a flow to time via entropy.... or it could just be that there was nothing and then there was something, I don't see how that is completely unimaginable... or it could be that our minds simply can't fathom what happened like a flatworm can't fathom that it's a flatworm.
He's basing this conclusion on a model that suggests that the peak production in oil will occur when we have used half of the world's oil, so he doesn't need to actually see the oil production drop off to conclude that we've reached the peak, he only needs to know when we've used half of all the world's oil. The estimate for how much oil has been produced so far seems pretty solid. The estimate for how much oil there is available seems questionable. Unfortunately it seems that you have to buy his book to really see what his method is for estimating this and decide whether or not it's reasonable. There are plenty of sites that discuss how to estimate this number, including some referenced on the wikepedia peak oil site, though I don't have a good sense for which estimates seem the most reasonable.
This is a really neat demonstration of the power of microlensing for planet finding. Though it's not the first, nor even the second, planet to be found this way (see for example http://xxx.lanl.gov/abs/astro-ph/0505451 and http://xxx.lanl.gov/abs/astro-ph/0505451), it really does show how microlensing can find small planets pretty far away from their host stars. It'll be a very good technique for determining the frequency of planets as small as the Earth. As for finding life on the microlensing discovered planets (using the future Terrestrial Planet Finder mission [http://planetquest.jpl.nasa.gov/TPF/tpf_index.cfm ] for example to search for biosignatures in their spectra), it'll be very difficult. The majority of these planets are going to be very far away from us (where there is the highest probability of finding a lens) and, by selection, they're going to have a second bright star very close by on the sky that will be difficult to coronagraph out. The microlensing planets are really all going to be one-shot deals where you have no hope of following them up in the foreseeable future. I think planets found by transits (the upcoming Kepler mission [http://kepler.nasa.gov/]) or by astrometry (the upcoming Space Interferometry Mission [http://sim.jpl.nasa.gov/]) will be much better bets for searching for life.
This is actually a pretty exciting result that's different from the case of SN 1987A in that they're seeing light from ancient SN which were never observed originally. It's the idea of discovering ancient supernovae by light echoes that's new, not just seeing a light echo from a supernova. You can see their paper at http://xxx.lanl.gov/abs/astro-ph/0510738.