A Canon 1DS Mark 3, the current speed-demon, comes close. It's got less resolution (I think they're somewhere around 20 MP) and about the same framerate (if you can get the data off the camera onto an SD card fast enough, but rigging up a custom data readout for a satellite isn't that hard.) From the specs quoted in the article (15km square from a height of 7.5km), they're using a seriously wide-angle lens setup on this thing. Sticking a tele lens (70-100mm, probably) on the Canon will probably give you about the same meters/pixel resolution, at the cost of a narrower field of view. Now just mount two of them on the satellite, if you insist on the same level of performance as the one in the article. (That'll give you about 50 mpix/sec; you can have that spread over whatever field of view you want by choice of lens.)
Also, consumer cameras (if you can call the 1Ds that, they're $thousands) have these nice things called zoom lenses. Just mount 70-200 IS zooms on the thing, and you can blow up anything you want even more detail on, at the cost of some resolution. You get the added benefit of not caring about vibration isolation on an airplane, since it's built into the lens.
Note that the only reason to use such expensive hardware is speed and a lack of complexity; a larger array of cheaper cameras would do just as well. My $400 consumer camera (Panasonic FZ50) can resolve 18 cm/pixel from 7.5 km. Hell, for the weight these things might be better than the Canons (they're much lighter); just mount however many of them you want on a plane and go. (Granted, you'd need a lot of them; they don't push out high-res images that fast.)
There's no reason to use custom-built hardware when Canon (or Nikon or Panasonic or whoever) is already mass-producing stuff that will get the job done cheaper, with more flexibility (zoom lenses, ability to add more cameras or swap lenses.)
One South African (native language: Afrikaans), two Germans, a Brazilian (I think), a Frenchwoman, an Indian, a Southerner (native language: drawl), a string theorist (native language: group theory) and a bunch of Chinese.
With the exception of the Chinese and maybe the string theorist, all of the TA's have better English skills than most of the (native English-speaking) American undergrads, who can't write a coherent lab report to save their lives.
So, I am a grad student, TA'ing a class in computational physics.
Said class is taught in the only lab in the building with Windows machines; everything else is Linux. The old Athlon XP boxes do just fine; I've got Monte Carlo running on some of them right now.
These computers are state-of-the-art: dual-core Pentiums, 2GB RAM, and... Vista Business.
1. Half the time you can't log in because "An error occurred contacting the User Profile Service." 2. Sometimes you can't log in because of some other error I forget. 3. The things take forever to boot. 4. The first thing the students do when they get into Vista is... ssh to a linux machine, so they can do their work. The *same* Linux machine, able to handle a dozen students numerically integrating shit without a problem. 5. We use some shitty software called Excursion that lets you get X graphics back through a Windows ssh session. Trouble is, it sucks and crashes all the damn time.
So we're using ~$2k of Windows licenses and a bunch of spiffy hardware to... run ssh badly. Lovely. And then the students submit their writeups as.docx's, and I have to fuss at them and ask for something I can read.
Concentrated solar power isn't competing with coal for cost-efficiency. Coal isn't an option, and we are (or should be) working to run the hell away from coal as quickly as possible.
The real competition is other forms of clean power generation, like nuclear. Nuclear's costs are about the same as coal; why build a concentrated solar plant when you can just build a nuke plant?
A while back the meter was defined artificially, by some marks on a post.
Then someone got the idea to peg it to another unit. Time and space are related, and the conversion between them is the speed of light. So the solution to the problem was to adopt a precise definition of c, thus defining the meter in terms of the second (defined elsewhere) and the speed of light (a constant).
Couldn't we peg the kilogram to either the meter or the second as well, using another fundamental constant as the conversion. Planck's constant is the obvious one. Here's a clunky definition:
Define the joule to be "The energy difference between two states which interfere with a frequency of 1.50919067 × 10^33 cycles per second" or "6.626068 × 10^-34 joule is the energy difference between two states which interfere with a frequency of 1 cycle per second." What is a second? That's defined empirically, based on a transition in cesium. Or you could define a joule as some fraction of the energy carried by a photon with such-and-such wavelength, or however you want to do it.
Now you've got the joule, the meter, and the second defined. The second is the only empirical one; the other two are defined in reference to it and two fundamental constants of the universe, h and c.
Then you define the kilogram as that mass which, when moving at a speed of 2N meters per second, has a kinetic energy of N joules, in the limit of small N (to dodge the relativistic correction). Or you could calculate the relativistic correction at 2 meters per second and put it into the definition.
It's a serious problem. I had a student ask me today how she was supposed to find the force of $SOMETHING when her little spring scale only read mass... (it had a scale in kg).
You could specify the density of water at $PRESSURE and at its maximum density (somewhere around 4 C). The only problem with doing this for high-precision measurements is: what is water? Some fraction of the hydrogen will be deuterium, and that'll throw off the density. What fraction of the hydrogen should be deuterium for "standard water"?
Motion sensors keyed to lights are cheap, even more effective at reducing crime, save power, and reduce the duty cycle of the lights to a fraction of a percent.
The only reason they cause less light pollution is that they are nearly monochromatic, so the astronomers can notch-filter their telescopes and kill most of the pollution.
People walking at night *do* experience glare. First off, lots of folks wear glasses. Secondly, the presence of streetlights, even assuming no stray reflections, *does* affect human vision by preventing the eye from becoming fully dark-adapted. Many lighting schemes actually make things worse by creating very uneven lighting patterns. The eye will wind up adjusting its levels based on those bright areas, and then be completely unable to see in the dark areas.
Naturally, anyone up to no good will be in those shadows where nobody can see, because their eyes are metering for the bright areas.
*Contrast*, not the absolute amount of light, is the real limiting factor here. Two examples:
I was out in the forest today and saw a bird land on a tree branch west of me, backlit by the setting sun. I couldn't tell what it was; it appeared completely black to me because my eyes were adjusted to the huge amount of light coming from the western sky. I can, however, override my camera's automatic exposure setting, and was able to get a picture (at ISO 100, fyi). There was plenty of light to see by, there was just too much light coming from what I didn't want to see. Your eyes don't have an exposure override.
You can also see quite well in a whole hell of a lot less light than you think. I've been in situations where moonlight is actually bright enough to be dazzling (compared to the previous starlight when the moon was obscured); starlight is even enough to see where you're going by.
Also, studies have been done that show that, when streetlights are removed from neighborhoods, crime actually goes down. Why? Because there are no shadows to hide in, and, if it's really that dark, the boogeyman (who's much less common than you think) won't be able to see you either without a flashlight. My neighborhood is unlit and is in a city with a pretty high crime rate (Tucson, Arizona); I've never felt unsafe because of the lack of streetlights.
Benefits of turning off the lights, since you asked:
1) It saves power. Gobs of power. 2) People can enjoy the natural world, and possibly learn something in the process. 3) Less damn glare, helps drivers and walkers (who can see just fine by moonlight/starlight 4) Astronomy. 5) It has been hinted at that excessive artificial lighting at night screws up people's circadian rhythms and might be responsible for certain sleep disorders, fatigue, depression, etc. This hasn't been shown conclusively yet, of course, and in any case looking at a 14" LCD like I am now is far worse.
Lying to recruits about the realities of what they're going to be asked to do once they join up is dishonest. If the Army is unable to recruit, perhaps it should reexamine what it does with its recruits? Or perhaps it should take the money used to pay the America's Army contractors (I know one; they're paid *handsomely*) and add it to Pvt. Smith's signing bonus?
Furthermore, I think you confuse "opposing America" with "opposing the current use of America's armed forces". There's a whole hell of a lot more to this country than the military.
From the lecture end: Realtime computer graphics can be useful for illustrating concepts that can't really be represented well in static drawings on a blackboard, especially those that involve time evolution.
Solutions to Schroedinger's equation in one dimension, for instance, mapping XYZ to x, Re(psi), Im(psi). Then do time evolution to illustrate things like wave packets.
Electromagnetic radiation is another -- computer graphics are useful for showing the fields produced by a charge moving in a particular way. For introductory students, programs that automatically generate the fields and equipotentials resulting from a given electrostatic charge distribution can be instructive if the students get to fiddle with it. (It's useless in lectures because it can be drawn on the board.)
Classical mechanics, since it deals with the motion of visible macroscopic objects, can usually be covered pretty easily with video clips and real things to fiddle with -- everyone studying rigid-body motion (Euler's equations, etc.) should see the tumbling wrench video shot aboard the space shuttle.
I've often wondered about the mean GRE scores of physics grads. I'm at the UA and got a 790 verbal, which is apparently unusual. (But probably half of my class got an 800 math along with me.)
If the MPAA wants to play by the legal rules that intellectual property and physical property go by the same rules, then how are they not guilty of receiving stolen property?
Slashdot Mirror
You could get an Asus laptop. Owned by the Taiwanese, and made in Taiwan (or at least that's what's stamped on the bottom of mine).
Why just buy from not-China when you can buy from their enemies?
you can blow up anything you want even more detail on, at the cost of some resolution.
Should have been "at the cost of some field of view."
Sorry, brains not working.
A Canon 1DS Mark 3, the current speed-demon, comes close. It's got less resolution (I think they're somewhere around 20 MP) and about the same framerate (if you can get the data off the camera onto an SD card fast enough, but rigging up a custom data readout for a satellite isn't that hard.) From the specs quoted in the article (15km square from a height of 7.5km), they're using a seriously wide-angle lens setup on this thing. Sticking a tele lens (70-100mm, probably) on the Canon will probably give you about the same meters/pixel resolution, at the cost of a narrower field of view. Now just mount two of them on the satellite, if you insist on the same level of performance as the one in the article. (That'll give you about 50 mpix/sec; you can have that spread over whatever field of view you want by choice of lens.)
Also, consumer cameras (if you can call the 1Ds that, they're $thousands) have these nice things called zoom lenses. Just mount 70-200 IS zooms on the thing, and you can blow up anything you want even more detail on, at the cost of some resolution. You get the added benefit of not caring about vibration isolation on an airplane, since it's built into the lens.
Note that the only reason to use such expensive hardware is speed and a lack of complexity; a larger array of cheaper cameras would do just as well. My $400 consumer camera (Panasonic FZ50) can resolve 18 cm/pixel from 7.5 km. Hell, for the weight these things might be better than the Canons (they're much lighter); just mount however many of them you want on a plane and go. (Granted, you'd need a lot of them; they don't push out high-res images that fast.)
There's no reason to use custom-built hardware when Canon (or Nikon or Panasonic or whoever) is already mass-producing stuff that will get the job done cheaper, with more flexibility (zoom lenses, ability to add more cameras or swap lenses.)
So, we've got some foreign TA's in my department.
One South African (native language: Afrikaans), two Germans, a Brazilian (I think), a Frenchwoman, an Indian, a Southerner (native language: drawl), a string theorist (native language: group theory) and a bunch of Chinese.
With the exception of the Chinese and maybe the string theorist, all of the TA's have better English skills than most of the (native English-speaking) American undergrads, who can't write a coherent lab report to save their lives.
So, I am a grad student, TA'ing a class in computational physics.
... Vista Business.
... ssh to a linux machine, so they can do their work. The *same* Linux machine, able to handle a dozen students numerically integrating shit without a problem.
... run ssh badly. Lovely. And then the students submit their writeups as .docx's, and I have to fuss at them and ask for something I can read.
Said class is taught in the only lab in the building with Windows machines; everything else is Linux. The old Athlon XP boxes do just fine; I've got Monte Carlo running on some of them right now.
These computers are state-of-the-art: dual-core Pentiums, 2GB RAM, and
1. Half the time you can't log in because "An error occurred contacting the User Profile Service."
2. Sometimes you can't log in because of some other error I forget.
3. The things take forever to boot.
4. The first thing the students do when they get into Vista is
5. We use some shitty software called Excursion that lets you get X graphics back through a Windows ssh session. Trouble is, it sucks and crashes all the damn time.
So we're using ~$2k of Windows licenses and a bunch of spiffy hardware to
Concentrated solar power isn't competing with coal for cost-efficiency. Coal isn't an option, and we are (or should be) working to run the hell away from coal as quickly as possible.
The real competition is other forms of clean power generation, like nuclear. Nuclear's costs are about the same as coal; why build a concentrated solar plant when you can just build a nuke plant?
I like it! This could be the next santorum!
So itunes will run under wine.
Who cares? It still sucks.
... and as far as I can tell the math people don't even know what a "measurement" is.
If we did physics because it was easy we'd be art history majors.
That'd be another way to do it once you get the joule, sure.
A while back the meter was defined artificially, by some marks on a post.
Then someone got the idea to peg it to another unit. Time and space are related, and the conversion between them is the speed of light. So the solution to the problem was to adopt a precise definition of c, thus defining the meter in terms of the second (defined elsewhere) and the speed of light (a constant).
Couldn't we peg the kilogram to either the meter or the second as well, using another fundamental constant as the conversion. Planck's constant is the obvious one. Here's a clunky definition:
Define the joule to be "The energy difference between two states which interfere with a frequency of 1.50919067 × 10^33 cycles per second" or "6.626068 × 10^-34 joule is the energy difference between two states which interfere with a frequency of 1 cycle per second." What is a second? That's defined empirically, based on a transition in cesium. Or you could define a joule as some fraction of the energy carried by a photon with such-and-such wavelength, or however you want to do it.
Now you've got the joule, the meter, and the second defined. The second is the only empirical one; the other two are defined in reference to it and two fundamental constants of the universe, h and c.
Then you define the kilogram as that mass which, when moving at a speed of 2N meters per second, has a kinetic energy of N joules, in the limit of small N (to dodge the relativistic correction). Or you could calculate the relativistic correction at 2 meters per second and put it into the definition.
It's a serious problem. I had a student ask me today how she was supposed to find the force of $SOMETHING when her little spring scale only read mass... (it had a scale in kg).
In physics we talk about the masses of things from single atoms to galaxies.
In that range, 1 ~= 2
You could specify the density of water at $PRESSURE and at its maximum density (somewhere around 4 C). The only problem with doing this for high-precision measurements is: what is water? Some fraction of the hydrogen will be deuterium, and that'll throw off the density. What fraction of the hydrogen should be deuterium for "standard water"?
Most likely his eyes never get a chance to fully dark-adapt because of the light coming from the ground. I imagine he looks down once in a while.
Motion sensors keyed to lights are cheap, even more effective at reducing crime, save power, and reduce the duty cycle of the lights to a fraction of a percent.
The only reason they cause less light pollution is that they are nearly monochromatic, so the astronomers can notch-filter their telescopes and kill most of the pollution.
Doesn't mean it's not there, or not ugly.
-1, Wrong and Uninformed
/ 054b_exposure_light_and_exposure_values.htm#Light) You can see with a lot less light than you think you can, if you'd just turn out the damn lights.
People walking at night *do* experience glare. First off, lots of folks wear glasses. Secondly, the presence of streetlights, even assuming no stray reflections, *does* affect human vision by preventing the eye from becoming fully dark-adapted. Many lighting schemes actually make things worse by creating very uneven lighting patterns. The eye will wind up adjusting its levels based on those bright areas, and then be completely unable to see in the dark areas.
Naturally, anyone up to no good will be in those shadows where nobody can see, because their eyes are metering for the bright areas.
*Contrast*, not the absolute amount of light, is the real limiting factor here. Two examples:
I was out in the forest today and saw a bird land on a tree branch west of me, backlit by the setting sun. I couldn't tell what it was; it appeared completely black to me because my eyes were adjusted to the huge amount of light coming from the western sky. I can, however, override my camera's automatic exposure setting, and was able to get a picture (at ISO 100, fyi). There was plenty of light to see by, there was just too much light coming from what I didn't want to see. Your eyes don't have an exposure override.
You can also see quite well in a whole hell of a lot less light than you think. I've been in situations where moonlight is actually bright enough to be dazzling (compared to the previous starlight when the moon was obscured); starlight is even enough to see where you're going by.
Starlight is 512 times dimmer than a streetlit street; moonlight is 64 times dimmer. (Reference: http://www.photokaboom.com/photography/learn/tips
Also, studies have been done that show that, when streetlights are removed from neighborhoods, crime actually goes down. Why? Because there are no shadows to hide in, and, if it's really that dark, the boogeyman (who's much less common than you think) won't be able to see you either without a flashlight. My neighborhood is unlit and is in a city with a pretty high crime rate (Tucson, Arizona); I've never felt unsafe because of the lack of streetlights.
Benefits of turning off the lights, since you asked:
1) It saves power. Gobs of power.
2) People can enjoy the natural world, and possibly learn something in the process.
3) Less damn glare, helps drivers and walkers (who can see just fine by moonlight/starlight
4) Astronomy.
5) It has been hinted at that excessive artificial lighting at night screws up people's circadian rhythms and might be responsible for certain sleep disorders, fatigue, depression, etc. This hasn't been shown conclusively yet, of course, and in any case looking at a 14" LCD like I am now is far worse.
RAM, however, is considerably more expensive.
Guild Wars will also run on lots of hardware, and looks pretty good for it.
A friend of mine runs it on a Geforce 4, 1024x768, medium settings, on a 1533 MHz Athlon XP with 512 MB RAM. Try that with any other modern game.
Lying to recruits about the realities of what they're going to be asked to do once they join up is dishonest. If the Army is unable to recruit, perhaps it should reexamine what it does with its recruits? Or perhaps it should take the money used to pay the America's Army contractors (I know one; they're paid *handsomely*) and add it to Pvt. Smith's signing bonus?
Furthermore, I think you confuse "opposing America" with "opposing the current use of America's armed forces". There's a whole hell of a lot more to this country than the military.
From the lecture end: Realtime computer graphics can be useful for illustrating concepts that can't really be represented well in static drawings on a blackboard, especially those that involve time evolution.
Solutions to Schroedinger's equation in one dimension, for instance, mapping XYZ to x, Re(psi), Im(psi). Then do time evolution to illustrate things like wave packets.
Electromagnetic radiation is another -- computer graphics are useful for showing the fields produced by a charge moving in a particular way. For introductory students, programs that automatically generate the fields and equipotentials resulting from a given electrostatic charge distribution can be instructive if the students get to fiddle with it. (It's useless in lectures because it can be drawn on the board.)
Classical mechanics, since it deals with the motion of visible macroscopic objects, can usually be covered pretty easily with video clips and real things to fiddle with -- everyone studying rigid-body motion (Euler's equations, etc.) should see the tumbling wrench video shot aboard the space shuttle.
I've often wondered about the mean GRE scores of physics grads. I'm at the UA and got a 790 verbal, which is apparently unusual. (But probably half of my class got an 800 math along with me.)
If the MPAA wants to play by the legal rules that intellectual property and physical property go by the same rules, then how are they not guilty of receiving stolen property?