I am not a lawyer, but I think that if you don't have to do this contractually, you don't have to do it. I doubt that you had to agree to a Non-Disclosure Agreement, for example, to take this class, but if you did, then the teacher might be within their rights.
So, ask if this is covered by contract. (Things may be different if you are under-age.)
This may not make you popular with the educational establishment, and they have their ways of retaliating, but I never cared about that.
Anyway, Tom Tomorrow asks what other revelations about the Bush administration are likely to follow. Anyone have any ideas?
I, for one, hope that the follow the money. Something like $ 8 billion USD was stolen in currency. Total theft in the last 8 years is likely to be above $ 100 billion USD. Nail the people who took it, and ask them what else they know about, and you will find out all sorts of interesting things.
Not quite true - the low lying areas on Mars are above the triple point (in pressure - i.e., below it in elevation) now. For example, the Phoenix polar lander was above the triple point for the entire time it sent back meteorological data. (Of course, there it is consistently too cold for liquid water.) The Viking Lander 2 was above the triple point at times, below it other times (there is a large annual variation in Mars surface pressure, and VL2 was close to the edge).
The bottom of the Hellas basin is another area consistently above the triple point, and there it does get warm enough that you might actually see liquid water on the surface.
Remember that salts will not generally freeze out in ice, especially ice that forms by precipitation (as is assumed for the Martian poles). I would assume that the polar caps are very pure ice, with some dust and dissolved CO2. If you melted it, the dust would drop out, and the result might very well be drinkable.
This is one case, though, where I think "Trust, but Verify" definitely applies.
Since Mars's Surface Area = 144 million km^2, this implies (for 2.5 million km^3 of ice) that ice caps are enough to supply a water layer 17 meters deep over the entire surface, or maybe 50 meters deep in Hellas and the Northern lowlands, if it was all melted. (If the polar caps entirely melted, that alone would raise the surface pressure above the triple point of water, so liquid water would be possible. The Hellas Basin is deep enough that the pressure is above the triple point now, and it definitely could have liquid water in it if the climate warmed some.)
Note that the polar caps show very clear signs of layering, presumably caused by the long period obliquity oscillations, and are in general very young geologically, so it is not beyond belief that, say, the Hellas basin fills up with water on a regular basis, every 500,000 years or so.
The media's reliance on a narrative "script" will, I think, be the death of corporate media. Time and again they show that it doesn't matter what is really going on, that what matters is the "conventional wisdom" that has been constructed around events. Almost literally nothing that doesn't fit that narrative will appear in print in the United States. So apparently the conventional wisdom is that Vista is flawed, and Windows 7 is a home run. Just wait - you will see the same problems previously lambasted in Vista ignored in Windows 7. That's the way it works. Why they continue to make money is a mystery to me.
The optical SETI people are interested in using solar arrays at night (as light buckets), and at least some of them can be pointed accurately enough to point at a given star, so I think that the answer to your question is yes. This is discussed further in SETI 2010.
I'd like to know when those four moons are _very_ close together, and preferably not in front of or behind Jupiter as seen from Earth.
Never. The inner 3 are a Laplace relationship, and are never close together. So, among other implications, the arrangement shown at the end of 2001 A Space Odyssey cannot happen.
I highly recommend Murrary and Dermott if you are interested in the physics of this.
Good post - you raise some points that I have wondered about.
Back when the Narrabi interferometer was in use, even a cooled photomultiplier might have a quantum efficiency of 10 or maybe 20%. Now, with CCDs, 80 % is possible, so that is a factor of 4 or so right there.
BUT, now there are all of these big light buckets looking for Cherenkov radiation from cosmic rays, and (as you point out) computer resources are dirt cheap, so the question I would have is, could you do useful "parasitic" observations using, say, Veritas ?
Note, by the way, that the various interplanetary gamma ray burst networks are also intensity interferometers. And, to answer your question, the SNR increases by the sqrt of the bandwidth. If you could do bandwidth synthesis, you might be able to really improve your angular precision (not resolution); that is linear in the bandwidth.
IANAS, but it appears that since these findings were obtained by a completely different process, they provide important confirmation of the Mars Express data-
Yes, more data is good, and seeing it from here is cool. I have no doubt whatsoever that the principal investigators understand all of this. The thing I don't like is how the actual details always seem to get ground up by the PR machinery and come out the other end as "discovers."
I believe that I have seen 4 or 5 "X discovers water on Mars," press releases in the last 10 years, for example.
Not quite. It says "similar techniques have also been used to make infrared and optical images of stellar surfaces"
In the optical, interferometry is done by actually combining light from two or more telescopes. So, first, the telescopes have to be close enough to do that. Second, the atmosphere limits your coherence between remote sites to 10's or 100's of meters at most (longer separation are possible in the IR than in the optical). Third, the wavelength is much smaller (a factor of ~ 10,000, typically), so source resolution effects (which in the radio start really hurting at an Earth radii or so), start really hurting at a few hundred meters or so. (The sources are typically different (stars versus quasars), but both tend to have sizes around a milli arc second or so.)
The canceled (but hopefully to be revived) SIM mission was an interferometer in space, where the atmospheric issues will not obtain, and you could get sufficient accuracy to see the effects of Earth size planets on their stars.
The real trouble with intensity interferometry is that you have only the square root of the sensitivity of phase interferometry, so typically you can only detect the very brightest sources.
The Narrabi intensity interferometer, for example, used 10 meter optical dishes IIRC and could only detect the brightest 32 stars, so it was substantially less sensitive to light than the human eye. (Great angular resolution, but very insensitive.)
Yes, this aperture synthesis is done to increase resolution, not sensitivity. In fact, all known radio sources have a finite size for VLBI (because of the inverse compton effect), and so source brightness starts to decline as baselines go towards two Earth radii. While VLBI has been done from space, if we placed a VLBI antenna on (say) Mars, there would almost certainly be no source visible on Earth-Mars baselines for any obtainable antenna size.
Dont get a crappy scope. it will simply discourage you.
Yes, it is hard to do VLBI with a telescope that is less than 5 meters in diameter. Also, you will need a good clock. VLBI has been done with Cesium or Rubidium standards, but I would strongly recommend that you pick up one of the excellent Russian masers. They will easily fit in your garage.
Slashdot Mirror
Seriously, what employer wouldn't want to be in the position to employ reasonably killed labor that *HAS* to work...
In my experience the dead do not work whether they need to or not.
I am not a lawyer, but I think that if you don't have to do this contractually, you don't have to do it. I doubt that you had to agree to a Non-Disclosure Agreement, for example, to take this class, but if you did, then the teacher might be within their rights.
So, ask if this is covered by contract. (Things may be different if you are under-age.)
This may not make you popular with the educational establishment, and they have their ways of retaliating, but I never cared about that.
Anyway, Tom Tomorrow asks what other revelations about the Bush administration are likely to follow. Anyone have any ideas?
I, for one, hope that the follow the money. Something like $ 8 billion USD was stolen in currency. Total theft in the last 8 years is likely to be above $ 100 billion USD. Nail the people who took it, and ask them what else they know about, and you will find out all sorts of interesting things.
Just wait till it comes out that they spied on Senators from the opposition party.
Not quite true - the low lying areas on Mars are above the triple point (in pressure - i.e., below it in elevation) now. For example, the Phoenix polar lander was above the triple point for the entire time it sent back meteorological data. (Of course, there it is consistently too cold for liquid water.) The Viking Lander 2 was above the triple point at times, below it other times (there is a large annual variation in Mars surface pressure, and VL2 was close to the edge).
The bottom of the Hellas basin is another area consistently above the triple point, and there it does get warm enough that you might actually see liquid water on the surface.
Remember that salts will not generally freeze out in ice, especially ice that forms by precipitation (as is assumed for the Martian poles). I would assume that the polar caps are very pure ice, with some dust and dissolved CO2. If you melted it, the dust would drop out, and the result might very well be drinkable.
This is one case, though, where I think "Trust, but Verify" definitely applies.
Since Mars's Surface Area = 144 million km^2, this implies (for 2.5 million km^3 of ice) that ice caps are enough to supply a water layer 17 meters deep over the entire surface, or maybe 50 meters deep in Hellas and the Northern lowlands, if it was all melted. (If the polar caps entirely melted, that alone would raise the surface pressure above the triple point of water, so liquid water would be possible. The Hellas Basin is deep enough that the pressure is above the triple point now, and it definitely could have liquid water in it if the climate warmed some.)
Note that the polar caps show very clear signs of layering, presumably caused by the long period obliquity oscillations, and are in general very young geologically, so it is not beyond belief that, say, the Hellas basin fills up with water on a regular basis, every 500,000 years or so.
The media's reliance on a narrative "script" will, I think, be the death of corporate media. Time and again they show that it doesn't matter what is really going on, that what matters is the "conventional wisdom" that has been constructed around events. Almost literally nothing that doesn't fit that narrative will appear in print in the United States. So apparently the conventional wisdom is that Vista is flawed, and Windows 7 is a home run. Just wait - you will see the same problems previously lambasted in Vista ignored in Windows 7. That's the way it works. Why they continue to make money is a mystery to me.
The optical SETI people are interested in using solar arrays at night (as light buckets), and at least some of them can be pointed accurately enough to point at a given star, so I think that the answer to your question is yes. This is discussed further in SETI 2010.
I'd like to know when those four moons are _very_ close together, and preferably not in front of or behind Jupiter as seen from Earth.
Never. The inner 3 are a Laplace relationship, and are never close together. So, among other implications, the arrangement shown at the end of 2001 A Space Odyssey cannot happen.
I highly recommend Murrary and Dermott if you are interested in the physics of this.
Oh, yes, and Starry Night will also do this. That might be best if you just want to do amateur astronomy.
I am sure that there are lots of other choices out there, but these are what come to mind right now.
Do you know of a site that predicts conjunctions of Jupiter's Galilean satellites from Earth's perspective?
Sky and Telescope has a Javascript utility.
JPL's Horizons on line system includes major satellites and will also provide orbital elements.
The USNO Nautical almanac also has this information if you want it in print.
Good post - you raise some points that I have wondered about.
Back when the Narrabi interferometer was in use, even a cooled photomultiplier might have a quantum efficiency of 10 or maybe 20%. Now, with CCDs, 80 % is possible, so that is a factor of 4 or so right there.
BUT, now there are all of these big light buckets looking for Cherenkov radiation from cosmic rays, and (as you point out) computer resources are dirt cheap, so the question I would have is, could you do useful "parasitic" observations using, say, Veritas ?
Note, by the way, that the various interplanetary gamma ray burst networks are also intensity interferometers. And, to answer your question, the SNR increases by the sqrt of the bandwidth. If you could do bandwidth synthesis, you might be able to really improve your angular precision (not resolution); that is linear in the bandwidth.
IANAS, but it appears that since these findings were obtained by a completely different process, they provide important confirmation of the Mars Express data-
Yes, more data is good, and seeing it from here is cool. I have no doubt whatsoever that the principal investigators understand all of this. The thing I don't like is how the actual details always seem to get ground up by the PR machinery and come out the other end as "discovers."
I believe that I have seen 4 or 5 "X discovers water on Mars," press releases in the last 10 years, for example.
Not quite. It says "similar techniques have also been used to make infrared and optical images of stellar surfaces"
In the optical, interferometry is done by actually combining light from two or more telescopes. So, first, the telescopes have to be close enough to do that. Second, the atmosphere limits your coherence between remote sites to 10's or 100's of meters at most (longer separation are possible in the IR than in the optical). Third, the wavelength is much smaller (a factor of ~ 10,000, typically), so source resolution effects (which in the radio start really hurting at an Earth radii or so), start really hurting at a few hundred meters or so. (The sources are typically different (stars versus quasars), but both tend to have sizes around a milli arc second or so.)
The canceled (but hopefully to be revived) SIM mission was an interferometer in space, where the atmospheric issues will not obtain, and you could get sufficient accuracy to see the effects of Earth size planets on their stars.
This was reported by Mars Express in 2004.
Do you mean the GMRT in India ?
It's operational.
I beg to differ - it is the size of the planet, it just has some holes in it !
The real trouble with intensity interferometry is that you have only the square root of the sensitivity of phase interferometry, so typically you can only detect the very brightest sources.
The Narrabi intensity interferometer, for example, used 10 meter optical dishes IIRC and could only detect the brightest 32 stars, so it was substantially less sensitive to light than the human eye. (Great angular resolution, but very insensitive.)
Note that that is "1 Gbps per telescope." It does add up.
But you have to wonder whether they'll have the charisma needed to keep Apple cool...
No, you have to wonder if they have the guts to pull the plug or drastically change one of Jobs's initiatives if it should become necessary.
I don't think Bill Gates is doing anything important right now...
He and Jerry Seinfeld were last seen trying to track down Alex Bogusky.
Yes, this aperture synthesis is done to increase resolution, not sensitivity. In fact, all known radio sources have a finite size for VLBI (because of the inverse compton effect), and so source brightness starts to decline as baselines go towards two Earth radii. While VLBI has been done from space, if we placed a VLBI antenna on (say) Mars, there would almost certainly be no source visible on Earth-Mars baselines for any obtainable antenna size.
Dont get a crappy scope. it will simply discourage you.
Yes, it is hard to do VLBI with a telescope that is less than 5 meters in diameter. Also, you will need a good clock. VLBI has been done with Cesium or Rubidium standards, but I would strongly recommend that you pick up one of the excellent Russian masers. They will easily fit in your garage.
He looked at the Sun through his telescope without any filter. It put permanent spots in his vision.
Do not try this at home. In fact, only try this after sunset but before sunrise no matter where you are.