Time to check again - the planetary masses have changed quite a bit since your last look. Jupiter is about 3.4 (not 50) times the mass of Saturn, and about 318 (not 1000) times that of Earth.
No. That's restating the problem. You don't have the understanding bit here. What is going on that will change the (I presume) I squared R losses in the magnet
Quick bit of advice: Don't casually presume that you know more about the subject of the article than the PhDs who contributed to it. The whole point of a superconducting magnet is that R=0, so there is no I^2 R loss* in the magnet.
But when you build a magnet like this, you can't calculate the magnetic force on every centimeter of superconducting wire in the whole thing. You also can't make the wire stay precisely where you put it. As the field builds up the first time, all the wires move around a little bit, due to the very large magnetic forces on them. This wastes some of the energy put into the field. As you cycle the field, the wires gradually move toward an equilibrium and the mechanical energy loss goes to zero.
I'm sure there are other factors, but this is the only one that I can remember off the top of my head. In fact, I know that there's more than this to the problem, because this is a well-known phenomenon that everybody who designs high-field magnets has dealt with. If it were as simple as this, they never would have mentioned it in the article.
* Of course, there are some losses in type II superconductors due to the motion of flux vorticies. But this doesn't behave quite like an Ohmic resistance, and the loss is really small in good alloys.
As the last reply stated, teslas are linear, just as most physical units are. As for field strengths, 13 T is only considered large for static-field magnets. Pulsed-field magnets can break 40 T without much trouble, but in much smaller volumes than this beast.
The important thing about this magnet isn't the field strength - it's the volume in which the field is that strong, as well as the geometry of the field. You need some pretty fucked-up fields in order to effectively confine plasma, and those fields can only be generated with hideously complicated magnet designs.
So give you ID card to the border guard
Your alias says you're Captain Jean Luc Picard
Of the United Federation of Planets
Cause he won't speak english anyway
Everybody knows that the world is full of stupid people
So meet me at the mission at midnight
We'll divvy up there
Everybody knows that the world is full of stupid people
Well I got the pistol
So I get the Pesos
That seems fair
If you read the end of the article, it explains that the top of the crawler is supported on a bunch of hydraulic cylinders which keep the platform level while the thing is moving.
I refer you to detonate.net's MatrixSE bastardization, page 26. (The same joke appears in the first Matrix bastardization, but SE's image quality is better)
Well, it's about 2/3 heavier than lead, and a whole hell of a lot harder. Tungsten also works well, but is rather expensive. Lots of uranium is/has been mined for nuclear power, but nuclear applications need enriched uranium, so there's a lot of surplus U-238 from the enrichment process (getting 3% U-235 from naturally occuring.5% U-235 means you have to get rid of about 80% of the U-238 you start with). Since the government is heavily involved with nuclear technology, the military probably gets their DU cheaper than they would on the open market, too.
... concluded that troops in a tank who survived being hit by a DU shell could double their risk of dying from lung cancer.
If you're in a tank that just got hit with a DU round, lung cancer is FAR from the top of your list of problems.
I can see it now...
SURGEON GENERAL'S WARNING: This sabot round contains depleted uranium. Occupants of a vehicle struck by this shell may suffer health problems.
Paul! I didn't know you bothered posting to/.. Hell, I just saw the headline and looked to see if Myself was posting here... And sho' enuf, there he is, lamenting the dismal prospects of resurrecting the Detroit network. Well, if Aerie isn't gonna do it, it's time to get the climbing gear and screwdrivers (only for use after climbing - don't climb drunk).
(Of course, if you survived that, your problems are just begining!)
Exactly. If you're close enough for the neutrinos to have any macroscopic effect, you're gonna be nothing but ionized H, O, N, C, etc. real soon (well, maybe in a few hours. The electromagnetic radiation can take a long time to reach the surface of a supernova, while the neutrinos get there at about the velocity of light). But the earlier poster warned about neutrinos after mentioning observing from a few light-years away, where the flux would be *far* too low to worry about.
Typically, you're correct. Traditional lasers emit almost all their energy at a single wavelength, with very small deviations of energy (determined by the time it takes an atom to emit a photon, thanks to the good ol' uncertainty principle, dE*dt>h/(2pi)). What Lucent did here is to create a whole mess of lasers in one package, which all emit slightly different wavelengths. The wavelength uncertainties overlap enough that you get a fairly smooth distribution of energy, rather than a single, well-defined peak at one wavelength.
Gallium is metallic, and conducts fairly well (resisitvity=14.7 micro-ohm*cm, probably a bit different in the liquid phase).
The diameter of the tubes, as quoted in the article, is 75nm (that's a lot more than one carbon atom across). The average interatomic spacing of liquid gallium atoms is.26nm, if I did my math right. So the tubes are ~300 gallium atoms across. (BTW, these sound like some exceptionally wide nanotubes.)
As for changing the temperature of the thermometer by reading it, there is of course some change. But at that scale, thermal conduction is pretty much instantaneous, so you heat up the whole system (gallium, carbon tube, and whatever it's mounted on) at once. The change in temperature of the entire system from the electron beam is presumably negligible.
I used to wash my trackball on a regular basis. Just take it apart, wash each piece in warm, soapy water, rinse thoroughly, and let dry for half an hour or so (depends on humidity). Never had a problem with it.
I *could not* get that out of my head for the entire lecture during which we derived one form of the 2nd law of thermodynamics from elementary probability.
I just did the same thing... Cursed misleading slashdot headlines! Making us reasonably informed scientific types look like morons. I guess it's our own fault though, it's not like this is the first time/. has had grossly optimistic headlines.
This effectively demonstrates the existence of gravitons. A graviton is simply a quantum of gravitational force, and showing that particles exist in discrete gravitational quantum states demonstrates that gravitation is quantized (duh). The next step is to reconcile quantized gravitation with general relativity, which ain't gonna be fun.
Well, we have plenty of RCS thrusters and ablative armor, and we don't need all the other stuff. Remember, the ultimate solution to any Star Trek problem is something we already know how to do: reverse the polarity!
Backflushing the bussard collectors messed up your phase discriminator calibration? Reverse the polarity! Pattern buffer's isolinear chips not working with the biomatter resequencer? Reverse the polarity! Isomagnetic disintegrator fried the power transfer conduit to the main deflector, making it impossible to reroute warp power to the tractor beam emitters? Reverse the polarity!
But if your self-sealing stem bolts break, you're completely screwed.
420 MeV?! Strange, most of my clothing is largely transparent to high energy gamma radiation. I'd sure like to see whatever material reflects photons of that energy.
The theoretical limit is one atom wide, on the order of ~2-5 angstroms (10^-10 m) for most metals. These wires are quoted as 10nm, or 100 angstroms across. That works out to about 50 atoms across for silver (face-centered cubic cell 4.09 angstroms on a side, 2 layers of atoms per cell), if I looked up the right value in the table.
Now back to studying for that solid state physics final.
1. The EPR paradox has no more implications for the existence of non-particle-mediated interactions than the collapse of a single particle's wavefunction does.
2. As numerous others have stated, quantum electrodynamics is entirely concerned with reconciling quantum mechanics with special relativity, and it works quite well. Both the uncertainty principle and special relativity are very important when describing particle interactions. It's general relativity and gravity that quantum mechanics doesn't get along with.
4. I never said proportional. Let's take the Planck time as a fundamental unit. The Planck time is proportional to c^(-5/2). If you make c smaller, the fundamental unit of time gets bigger, and everything takes longer, i.e. time passes more slowly. The change isn't the same for all processes, but that's because the relative strengths of forces also depend on c.
Slashdot Mirror
(Data from here, specifically these pages.)
Quick bit of advice: Don't casually presume that you know more about the subject of the article than the PhDs who contributed to it. The whole point of a superconducting magnet is that R=0, so there is no I^2 R loss* in the magnet.
But when you build a magnet like this, you can't calculate the magnetic force on every centimeter of superconducting wire in the whole thing. You also can't make the wire stay precisely where you put it. As the field builds up the first time, all the wires move around a little bit, due to the very large magnetic forces on them. This wastes some of the energy put into the field. As you cycle the field, the wires gradually move toward an equilibrium and the mechanical energy loss goes to zero.
I'm sure there are other factors, but this is the only one that I can remember off the top of my head. In fact, I know that there's more than this to the problem, because this is a well-known phenomenon that everybody who designs high-field magnets has dealt with. If it were as simple as this, they never would have mentioned it in the article.
* Of course, there are some losses in type II superconductors due to the motion of flux vorticies. But this doesn't behave quite like an Ohmic resistance, and the loss is really small in good alloys.
The important thing about this magnet isn't the field strength - it's the volume in which the field is that strong, as well as the geometry of the field. You need some pretty fucked-up fields in order to effectively confine plasma, and those fields can only be generated with hideously complicated magnet designs.
Your alias says you're Captain Jean Luc Picard
Of the United Federation of Planets
Cause he won't speak english anyway
Everybody knows that the world is full of stupid people
So meet me at the mission at midnight
We'll divvy up there
Everybody knows that the world is full of stupid people
Well I got the pistol
So I get the Pesos
That seems fair
Wrong captain, but close enough.
If you read the end of the article, it explains that the top of the crawler is supported on a bunch of hydraulic cylinders which keep the platform level while the thing is moving.
I refer you to detonate.net's MatrixSE bastardization, page 26. (The same joke appears in the first Matrix bastardization, but SE's image quality is better)
Well, it's about 2/3 heavier than lead, and a whole hell of a lot harder. Tungsten also works well, but is rather expensive. Lots of uranium is/has been mined for nuclear power, but nuclear applications need enriched uranium, so there's a lot of surplus U-238 from the enrichment process (getting 3% U-235 from naturally occuring .5% U-235 means you have to get rid of about 80% of the U-238 you start with). Since the government is heavily involved with nuclear technology, the military probably gets their DU cheaper than they would on the open market, too.
If you're in a tank that just got hit with a DU round, lung cancer is FAR from the top of your list of problems.
I can see it now...
SURGEON GENERAL'S WARNING: This sabot round contains depleted uranium. Occupants of a vehicle struck by this shell may suffer health problems.
One American death is a tragedy. One million Afghan deaths is a statistic.
Paul! I didn't know you bothered posting to /.. Hell, I just saw the headline and looked to see if Myself was posting here... And sho' enuf, there he is, lamenting the dismal prospects of resurrecting the Detroit network. Well, if Aerie isn't gonna do it, it's time to get the climbing gear and screwdrivers (only for use after climbing - don't climb drunk).
Exactly. If you're close enough for the neutrinos to have any macroscopic effect, you're gonna be nothing but ionized H, O, N, C, etc. real soon (well, maybe in a few hours. The electromagnetic radiation can take a long time to reach the surface of a supernova, while the neutrinos get there at about the velocity of light). But the earlier poster warned about neutrinos after mentioning observing from a few light-years away, where the flux would be *far* too low to worry about.
For the same reason they don't care about shielding, they don't care about you, either.
And I'm still waiting for those gravitational waves to get observed. It would be so danmed cool to listen to the creation of a black hole that way...
Typically, you're correct. Traditional lasers emit almost all their energy at a single wavelength, with very small deviations of energy (determined by the time it takes an atom to emit a photon, thanks to the good ol' uncertainty principle, dE*dt>h/(2pi)). What Lucent did here is to create a whole mess of lasers in one package, which all emit slightly different wavelengths. The wavelength uncertainties overlap enough that you get a fairly smooth distribution of energy, rather than a single, well-defined peak at one wavelength.
The diameter of the tubes, as quoted in the article, is 75nm (that's a lot more than one carbon atom across). The average interatomic spacing of liquid gallium atoms is .26nm, if I did my math right. So the tubes are ~300 gallium atoms across. (BTW, these sound like some exceptionally wide nanotubes.)
As for changing the temperature of the thermometer by reading it, there is of course some change. But at that scale, thermal conduction is pretty much instantaneous, so you heat up the whole system (gallium, carbon tube, and whatever it's mounted on) at once. The change in temperature of the entire system from the electron beam is presumably negligible.
I used to wash my trackball on a regular basis. Just take it apart, wash each piece in warm, soapy water, rinse thoroughly, and let dry for half an hour or so (depends on humidity). Never had a problem with it.
I *could not* get that out of my head for the entire lecture during which we derived one form of the 2nd law of thermodynamics from elementary probability.
I just did the same thing... Cursed misleading slashdot headlines! Making us reasonably informed scientific types look like morons. I guess it's our own fault though, it's not like this is the first time /. has had grossly optimistic headlines.
Yeah, I just read a much more informed comment that makes me look like a complete idiot. Sorry about that one.
This effectively demonstrates the existence of gravitons. A graviton is simply a quantum of gravitational force, and showing that particles exist in discrete gravitational quantum states demonstrates that gravitation is quantized (duh). The next step is to reconcile quantized gravitation with general relativity, which ain't gonna be fun.
Backflushing the bussard collectors messed up your phase discriminator calibration? Reverse the polarity! Pattern buffer's isolinear chips not working with the biomatter resequencer? Reverse the polarity! Isomagnetic disintegrator fried the power transfer conduit to the main deflector, making it impossible to reroute warp power to the tractor beam emitters? Reverse the polarity!
But if your self-sealing stem bolts break, you're completely screwed.
420 MeV?! Strange, most of my clothing is largely transparent to high energy gamma radiation. I'd sure like to see whatever material reflects photons of that energy.
Now back to studying for that solid state physics final.
A. Annals of Physics
B. New England Journal of Medicine
C. New Scientist
D. None of the above
This story provides yet more evidence for C.
'nuff said.
2. As numerous others have stated, quantum electrodynamics is entirely concerned with reconciling quantum mechanics with special relativity, and it works quite well. Both the uncertainty principle and special relativity are very important when describing particle interactions. It's general relativity and gravity that quantum mechanics doesn't get along with.
4. I never said proportional. Let's take the Planck time as a fundamental unit. The Planck time is proportional to c^(-5/2). If you make c smaller, the fundamental unit of time gets bigger, and everything takes longer, i.e. time passes more slowly. The change isn't the same for all processes, but that's because the relative strengths of forces also depend on c.