My homeowners insurance charges something like $10 per YEAR for computer insurance that also includes... smartphones. With a $50 deductible and $1000 per incident. My some dropped my wife's Samsung Somethingorother in the pool and the insurance paid out ~$500 for a new phone. Way cheaper than any other plan I have ever seen for phones. It also covers laptops, and all devices in the house are covered under the single $10 payment.
It's hard not to have a few hacked servers when you comprise 1/255 (approx) of IPv4 space with everything sitting on an enormous pipe. Plus there's such a high flux of students coming, setting up servers (sometimes in closets), and leaving that there is a nightmare of unpatched everything there. Plus school is a place where you are supposed to learn, and a lot of learning comes from making mistakes.
You can download the article from Arxiv for free here: http://arxiv.org/abs/1103.3643
Basically, the imaging resolution of a lens (typically) has to do with its numerical aperture (NA). A small lens far away has terrible resolution, and vice-versa. The trouble with really high NA lenses is that they are hard to make without distortions. It's easy to make spherical shapes, but aptly named spherical distortion starts to ruin your image once the NA gets high. So what they've done is taken a ground glass surface and put it really close to the object, so that the "scattering lens" subtends close to 2pi steradians. Then they use a spatial light modulator (transmissive LCD screen) to control the phase of their laser beam across many domains to sort of pick out the random scattering elements on the frosted screen that give them the best image. Sort of. There is much additional trickery, but I think that's the jist of it.
While CPU power seems to double every 18 months or so, for the past (almost) 20 years hard drive size has doubled every 14 months*. Eventually hard drives will be so large that CPUs will never be able to access all the information. I guess then the key is being able to find the information you want to access, which is why I suppose it would be good to buy GOOG even now.
* 40 MB in 1991, 3 TB in 2010. This trend has held true at many points in between.
Well I didn't say my code was *well* written. Apparently there's a lot of trickery with copying global memory to cached memory to speed up operations. Cached memory takes (IIRC) one clock cycle to read or write, and global GPU memory takes six hundred cycles. And there's all this whatnot and nonsense about aligning your threads with memory locations that I don't even bother with.
The Tesla 1060 is a video card with no video output (strictly for processing) that has something like 240 processor cores and 4 GB of DDR3 RAM. Just doing math on large arrays (1k x 1k) I get a performance boost of about a factor of forty over a dual core 3.0 GHz Xeon.
The CUDA extension set has FFT functionality built in as well, so it's excellent for signal processing. The SDK and programming paradigm is super easy to learn. I only know C (and not C++) and I can't even make a proper GUI, but I can make my array functions run massively in parallel.
The trick is to minimize memory moving between the CPU and the GPU because that kills performance. Only the brand newest cards support functionality for "simultaneous copy and execute" where one thread can be reading new data to the card, another can be processing, and the third can be moving the results off the card.
One way that the video people can maybe speed up their processing (disclaimer: I don't know anything about this) is to do a quick sweep for keyframes, and then send the video streams between keyframes to individual processor cores. So instead of each core gets a piece of the frame, maybe each core gets a piece of the movie.
The days of the math coprocessor card have returned!
This paper from MIT showed conclusively through experiment (almost 4 years ago) that in a refractive material the medium temporarily gives up its momentum to the photon, so that the momentum of the photon in the medium is nhk.
It's too bad that this new experiment didn't cite the prior art.
In kind of a weird corollary to Moore's law, the storage capacity of "affordable" consumer hard drives has doubled about every 14 months since at least 1991.
In the summer 1991 a 40 MB drive was "good", and in the summer of 2008 a 1 TB drive is "good". That's a doubling period of almost exactly 14 months. I don't have the data to back up the dates in between, but I remember doing this calculation several years ago and getting the same number.
If Moore's law continues to hold true, and processing power doubles every 18 months, yet storage capacity doubles every 14 months, at some point we will have so much storage that our processors will not have the capacity to ever utilize it all.
There is also an energy consideration when discussing extracting oil that is not currently profitable. If it takes more than one barrle of oil energy equivalent to extract one barrel of oil, then it can never be done economically, even at $300/barrel.
You are wrong. What if I build a nuclear reactor next to my oil well? Then I can spend 5 units of (relatively) cheap nuclear energy to get one unit of oil energy, and I will probably turn a profit. People are willing to pay more for energy they can drive around with.
I actually got a 19. I had a two guesses (one wrong) where it actually made no sound at all because it was trying to play too fast. It seems to keep speeding up until your error rate hits some threshold.
I was just proud to get half at time of the "top performers". Yay. You would think they would skew the scores the other way to get old people to buy their crap. Or maybe it's skewed this way (I am in the youngest age bracket) to make old people who compare their scores with their kid's (or grandkid's) score even more worried.
So at least 27 ms isn't a minimum score.
m
Obesity comes from a simple condition...
on
Obesity Contagious?
·
· Score: 1, Insightful
...it's called "intaking more calories than you output."
Sure, some people have higher appetites, or lower metabolisms, but a virus isn't going to manufacture mass out of the celestial aether. If you eat less than your body requires, you lose weight, and vice-versa.
Most BECs are smaller than 100 million atoms. That many atoms undergoing fission at once (even if possible) would only emit a tiny amount of energy. BEC is also *very* dilute. About 10^14 particles per cubic centimeter. Thus the absorption cross section for a neutron emitted from within the cloud is negligible. It's pretty much impossible to make bigger BECs because of limitations due to bad collisions (spin mixing) at high densities and cooling rates.
And the other poster's comments about "heating it up really quick" is pretty much wrong, as far as I can tell.
I work with BEC, and there's no way it could be used as a weapon.
But your question about nuclear decay from a group wavefunction is pretty interesting, but the nuclei should behave independently. When a BEC scatters a photon, for instance, a single atom is rejected.
People seem to have gotten their cause and effect mixed up regarding the ocean's currents.
The rotation of the earth, along with wind is the primary mechanism for driving the gulf stream. Hot and cold water rising and falling has nothin to do with it - although it does have something to do with nutrient distribution.
The gulf stream current will not stop running unless the entire oceam freezes or the earth stops spinning. It's a matter of fluid mechanics. See this for basic details.
Whether some flow is diverted (making Europe a little cooler) is another story, but the fluctuations are just as likely a part of chaos that is a part of most fluid systems.
Basically light is absorbed at a point of damage in the fiber, creating a tiny plasma ball that burns backwards towards the source and destroys the fiber, preventing further output. The size of the plasma ball is very small (on the order of the size of the fiber core).
Maybe you just stuff some graphite between the bare fiber and the jacket. Then when the fiber core breaks it superheats a tiny bit of the graphite and begins the fiber fuse process - preventing further transmission of laser light.
I work with 20 Watt NIR laser, and I've burned myself with it. When you hold your finger in the beam accidentally, it hurts, and you move your finger.
The thing here is that it is a collimated beam. The kind that doesn't really lose its power density over distance. So I can be burned many meters away. This light must be coupled into a fiber with a high numerical aperture lens - and by the same token the light must be collimated when leaving the fiber.
Straight out the end of a broken or cut fiber, the light is highly divergent. It would take less than a meter for the 20 W beam to become eye safe (but maybe not eye smart). The only way for a bare fiber to hurt anything is if it brushes right against it, and even then it's a pretty small wound compared to the size of any organ.
I'm interested to see their justification for all of this.
maybe the european one is 2000 feet, but not the two in th US. actually, the full length of each arm is 4000 m. i've been to the facility, touched a beamtube, drove to the end. meters.
actually, the correct answer is that the path length does change, and you do see it. it's a gravitational strain, not necessarily the direct bending of spacetime that you are imaging. it's not totally intuitive, but it does work.
uh, one big problem with this is coherence. i don't think anyone in the physics community has floated this idea publicly. mostly because it's hard to make a BEC interferemeter that's even 10 MICRONS long. trust me, i know. i'm actually trying to do almost that right now.
what's funnier is i'm not kidding. i'm in lab right now. at 2am on a sunday. sigh.
i will try again here. so one case of the "gravitational wave" theory is that when two black holes spiral around one another (or any two large masses), they will emit energy in the form of gravitational waves, like two boats circling in a lake. physicists would like to detect this energy.
let me digress for a second to radio. normal EM radiation is in the dipole form. which means the radiation makes charges (electrons in an antenna) oscillate up and down. gravitational waves (i think) hit us in the higher order quadrupole mode, which instead of "up and down" is more like "in and out". or taking a circle and squishing it along one axis, and then the other.
so lets say you are standing on a field. then you have two stones hanging on strings, one 100m north, and the other 100m east. when a gravitational wave passes, if you were God, you would be able to notice that the north stone was pushed closer while the east one was pushed away, then the east one was pulled toward you while the north one was pushed away.
to detect this *infinitesimally* small force, you replace the rocks with mirrors. and put the mirrors in vacuum to prevent them being jittered by air molecules and strange index of refraction effects with the air. then put the mirrors really far apart to increase the relative sensitivity to the same strain.
now take a laser beam, split it where you stand and send half the beam to each mirror. the beam then returns to you, you recombine it at the same beamsplitter, and the photons in the laser beam will interfere. whether this interference is *bright* or *dark* depends on the relative path length difference of the two arms.
you can detect changes on the order of 1/100 wavelength (actually, much less, but that's more complicated) which is about 1e-8 meters. since the interferometer is 2e3 meters long, that means you can detect a fractional change of about 1 part in 1e11. but it's actually crazy better than that due to many smart inventions the LIGO people created about locking optical cavities. you get the idea.
so then you watch your interference as a function of time, then go to your astronomy books to see what events should create gravitational waves at the frequency you have observed them.
in a nutshell.
m
ps. analogy: a radio telescope uses electronic amplifiers to measure the induced motion of electrons from EM waves : a GW telescope uses a high finesse optical cavity to measure the induced motion of masses from gravitational waves
anyways, the purpose of the interferometer is to measure the differential gravitational strain between two remote masses. as a gravity wave passes (supposedly), two masses will be driven to oscillate in quadrature with one another. that means that relative to some fixed point, one mass will be drawn closer, and at a right angle another mass will be pushed further away. IIRC.
luckily a michelson interferometer is a great way to detect these small changes, where the remote masses are mirrors. the extremely long beam paths increase the sensitity of the device. and two remote locations are needed for local error cancellation. if you have three locations (there is a LIGO opening in louisiana soon. uh, maybe) then you can actually do gravitiational wave astronomy.
probably some LIGO person will write a better explanation, but it's late.
Slashdot Mirror
Amica. They've been pretty solid.
My homeowners insurance charges something like $10 per YEAR for computer insurance that also includes... smartphones. With a $50 deductible and $1000 per incident. My some dropped my wife's Samsung Somethingorother in the pool and the insurance paid out ~$500 for a new phone. Way cheaper than any other plan I have ever seen for phones. It also covers laptops, and all devices in the house are covered under the single $10 payment.
It's hard not to have a few hacked servers when you comprise 1/255 (approx) of IPv4 space with everything sitting on an enormous pipe. Plus there's such a high flux of students coming, setting up servers (sometimes in closets), and leaving that there is a nightmare of unpatched everything there. Plus school is a place where you are supposed to learn, and a lot of learning comes from making mistakes.
You can download the article from Arxiv for free here: http://arxiv.org/abs/1103.3643
Basically, the imaging resolution of a lens (typically) has to do with its numerical aperture (NA). A small lens far away has terrible resolution, and vice-versa. The trouble with really high NA lenses is that they are hard to make without distortions. It's easy to make spherical shapes, but aptly named spherical distortion starts to ruin your image once the NA gets high. So what they've done is taken a ground glass surface and put it really close to the object, so that the "scattering lens" subtends close to 2pi steradians. Then they use a spatial light modulator (transmissive LCD screen) to control the phase of their laser beam across many domains to sort of pick out the random scattering elements on the frosted screen that give them the best image. Sort of. There is much additional trickery, but I think that's the jist of it.
While CPU power seems to double every 18 months or so, for the past (almost) 20 years hard drive size has doubled every 14 months*. Eventually hard drives will be so large that CPUs will never be able to access all the information. I guess then the key is being able to find the information you want to access, which is why I suppose it would be good to buy GOOG even now.
* 40 MB in 1991, 3 TB in 2010. This trend has held true at many points in between.
Well I didn't say my code was *well* written. Apparently there's a lot of trickery with copying global memory to cached memory to speed up operations. Cached memory takes (IIRC) one clock cycle to read or write, and global GPU memory takes six hundred cycles. And there's all this whatnot and nonsense about aligning your threads with memory locations that I don't even bother with.
The Tesla 1060 is a video card with no video output (strictly for processing) that has something like 240 processor cores and 4 GB of DDR3 RAM. Just doing math on large arrays (1k x 1k) I get a performance boost of about a factor of forty over a dual core 3.0 GHz Xeon.
The CUDA extension set has FFT functionality built in as well, so it's excellent for signal processing. The SDK and programming paradigm is super easy to learn. I only know C (and not C++) and I can't even make a proper GUI, but I can make my array functions run massively in parallel.
The trick is to minimize memory moving between the CPU and the GPU because that kills performance. Only the brand newest cards support functionality for "simultaneous copy and execute" where one thread can be reading new data to the card, another can be processing, and the third can be moving the results off the card.
One way that the video people can maybe speed up their processing (disclaimer: I don't know anything about this) is to do a quick sweep for keyframes, and then send the video streams between keyframes to individual processor cores. So instead of each core gets a piece of the frame, maybe each core gets a piece of the movie.
The days of the math coprocessor card have returned!
Wow, you are correct. When I downloaded the paper and scanned the references, I somehow didn't see the reference listed.
My mistake.
I guess I have to change my point to "how is this new now?" But I guess a nice experiment in any case.
sorry.
n = (index of refraction)
h = (well, hbar, the planck constant)
k = (photon wavenumber)
http://arxiv.org/abs/cond-mat/0502014
This paper from MIT showed conclusively through experiment (almost 4 years ago) that in a refractive material the medium temporarily gives up its momentum to the photon, so that the momentum of the photon in the medium is nhk.
It's too bad that this new experiment didn't cite the prior art.
In kind of a weird corollary to Moore's law, the storage capacity of "affordable" consumer hard drives has doubled about every 14 months since at least 1991.
In the summer 1991 a 40 MB drive was "good", and in the summer of 2008 a 1 TB drive is "good". That's a doubling period of almost exactly 14 months. I don't have the data to back up the dates in between, but I remember doing this calculation several years ago and getting the same number.
If Moore's law continues to hold true, and processing power doubles every 18 months, yet storage capacity doubles every 14 months, at some point we will have so much storage that our processors will not have the capacity to ever utilize it all.
There is also an energy consideration when discussing extracting oil that is not currently profitable. If it takes more than one barrle of oil energy equivalent to extract one barrel of oil, then it can never be done economically, even at $300/barrel.
You are wrong. What if I build a nuclear reactor next to my oil well? Then I can spend 5 units of (relatively) cheap nuclear energy to get one unit of oil energy, and I will probably turn a profit. People are willing to pay more for energy they can drive around with.
I actually got a 19. I had a two guesses (one wrong) where it actually made no sound at all because it was trying to play too fast. It seems to keep speeding up until your error rate hits some threshold.
I was just proud to get half at time of the "top performers". Yay. You would think they would skew the scores the other way to get old people to buy their crap. Or maybe it's skewed this way (I am in the youngest age bracket) to make old people who compare their scores with their kid's (or grandkid's) score even more worried.
So at least 27 ms isn't a minimum score.
m
...it's called "intaking more calories than you output."
.this is not a sig
Sure, some people have higher appetites, or lower metabolisms, but a virus isn't going to manufacture mass out of the celestial aether. If you eat less than your body requires, you lose weight, and vice-versa.
m
Most BECs are smaller than 100 million atoms. That many atoms undergoing fission at once (even if possible) would only emit a tiny amount of energy. BEC is also *very* dilute. About 10^14 particles per cubic centimeter. Thus the absorption cross section for a neutron emitted from within the cloud is negligible. It's pretty much impossible to make bigger BECs because of limitations due to bad collisions (spin mixing) at high densities and cooling rates.
.this is not a sig
And the other poster's comments about "heating it up really quick" is pretty much wrong, as far as I can tell.
I work with BEC, and there's no way it could be used as a weapon.
But your question about nuclear decay from a group wavefunction is pretty interesting, but the nuclei should behave independently. When a BEC scatters a photon, for instance, a single atom is rejected.
m
3. With ocean levels higher, the ocean is able to absorb more energy, which shuts down the warm ocean currents.
This statement is false, I'm pretty sure. Oceanic currents are driven by the Earth's rotation and some wind, as I've commented in this thread.
Also, your step (4) leads directly back to step (1).
m
People seem to have gotten their cause and effect mixed up regarding the ocean's currents.
The rotation of the earth, along with wind is the primary mechanism for driving the gulf stream. Hot and cold water rising and falling has nothin to do with it - although it does have something to do with nutrient distribution.
The gulf stream current will not stop running unless the entire oceam freezes or the earth stops spinning. It's a matter of fluid mechanics. See this for basic details.
Whether some flow is diverted (making Europe a little cooler) is another story, but the fluctuations are just as likely a part of chaos that is a part of most fluid systems.
m
http://www.rp-photonics.com/fiber_fuse.html
Basically light is absorbed at a point of damage in the fiber, creating a tiny plasma ball that burns backwards towards the source and destroys the fiber, preventing further output. The size of the plasma ball is very small (on the order of the size of the fiber core).
Maybe you just stuff some graphite between the bare fiber and the jacket. Then when the fiber core breaks it superheats a tiny bit of the graphite and begins the fiber fuse process - preventing further transmission of laser light.
And then maybe I just gave away a $1M invention.
-m
I work with 20 Watt NIR laser, and I've burned myself with it. When you hold your finger in the beam accidentally, it hurts, and you move your finger.
.this is not a sig
The thing here is that it is a collimated beam. The kind that doesn't really lose its power density over distance. So I can be burned many meters away. This light must be coupled into a fiber with a high numerical aperture lens - and by the same token the light must be collimated when leaving the fiber.
Straight out the end of a broken or cut fiber, the light is highly divergent. It would take less than a meter for the 20 W beam to become eye safe (but maybe not eye smart). The only way for a bare fiber to hurt anything is if it brushes right against it, and even then it's a pretty small wound compared to the size of any organ.
I'm interested to see their justification for all of this.
-m
METERS
try reading http://en.wikipedia.org/wiki/LIGO
maybe the european one is 2000 feet, but not the two in th US. actually, the full length of each arm is 4000 m. i've been to the facility, touched a beamtube, drove to the end. meters.
m
actually, the correct answer is that the path length does change, and you do see it. it's a gravitational strain, not necessarily the direct bending of spacetime that you are imaging. it's not totally intuitive, but it does work.
m
uh, one big problem with this is coherence. i don't think anyone in the physics community has floated this idea publicly. mostly because it's hard to make a BEC interferemeter that's even 10 MICRONS long. trust me, i know. i'm actually trying to do almost that right now.
what's funnier is i'm not kidding. i'm in lab right now. at 2am on a sunday. sigh.
m
with a machine like this paving a 4 lane highway at a mile a minute would be a snap!
i will try again here. so one case of the "gravitational wave" theory is that when two black holes spiral around one another (or any two large masses), they will emit energy in the form of gravitational waves, like two boats circling in a lake. physicists would like to detect this energy.
let me digress for a second to radio. normal EM radiation is in the dipole form. which means the radiation makes charges (electrons in an antenna) oscillate up and down. gravitational waves (i think) hit us in the higher order quadrupole mode, which instead of "up and down" is more like "in and out". or taking a circle and squishing it along one axis, and then the other.
so lets say you are standing on a field. then you have two stones hanging on strings, one 100m north, and the other 100m east. when a gravitational wave passes, if you were God, you would be able to notice that the north stone was pushed closer while the east one was pushed away, then the east one was pulled toward you while the north one was pushed away.
to detect this *infinitesimally* small force, you replace the rocks with mirrors. and put the mirrors in vacuum to prevent them being jittered by air molecules and strange index of refraction effects with the air. then put the mirrors really far apart to increase the relative sensitivity to the same strain.
now take a laser beam, split it where you stand and send half the beam to each mirror. the beam then returns to you, you recombine it at the same beamsplitter, and the photons in the laser beam will interfere. whether this interference is *bright* or *dark* depends on the relative path length difference of the two arms.
you can detect changes on the order of 1/100 wavelength (actually, much less, but that's more complicated) which is about 1e-8 meters. since the interferometer is 2e3 meters long, that means you can detect a fractional change of about 1 part in 1e11. but it's actually crazy better than that due to many smart inventions the LIGO people created about locking optical cavities. you get the idea.
so then you watch your interference as a function of time, then go to your astronomy books to see what events should create gravitational waves at the frequency you have observed them.
in a nutshell.
m
ps. analogy: a radio telescope uses electronic amplifiers to measure the induced motion of electrons from EM waves : a GW telescope uses a high finesse optical cavity to measure the induced motion of masses from gravitational waves
i won't even get into it.
anyways, the purpose of the interferometer is to measure the differential gravitational strain between two remote masses. as a gravity wave passes (supposedly), two masses will be driven to oscillate in quadrature with one another. that means that relative to some fixed point, one mass will be drawn closer, and at a right angle another mass will be pushed further away. IIRC.
luckily a michelson interferometer is a great way to detect these small changes, where the remote masses are mirrors. the extremely long beam paths increase the sensitity of the device. and two remote locations are needed for local error cancellation. if you have three locations (there is a LIGO opening in louisiana soon. uh, maybe) then you can actually do gravitiational wave astronomy.
probably some LIGO person will write a better explanation, but it's late.
m