RAM is now cheaper when it comes to memory-per-unitofcurrency than hard drives.
Memory is ridiculously cheap, but its still not quite cheaper than hard drive space. Even if you can get 1 GB of memory for $60, you can get a 20-40 GB hard drive for about the same price.
I understand magnetic cooling, though maybe I was a little sloppy in describing it. Yes, its the gradients in the magnetic field which allow for cooling, but just as magnetic fields are ubiquitous in the universe, so are B field gradients.
As for B field gradient in space, it doesn't have to three dimensional. A stable gradient in one dimension is sufficient, as long as the plasma is trapped long enough so that the perpendicular energy can have time to be transferred (probably by collisions) to the parallel direction. While this is happening the parallel direction will be cooled by the magnetic bottle. So the parallel temperature will be hotter than the parallel temperature, but both directions will be cooling. Now yes the CMB radiation will still be there, so in order to get the plasma temperature below the the CMB temperature, the magnetic cooling rate would have to higher than the rate at which the plasma absorbs energy from the CMB (and other sources of) radiation. No, this isn't terribly likely, but the universe is a big place, so my bet is that it has happened.
As for intellegent life in the universe, I would be surprised if there aren't billions of intelligent species out there. Even if there were only 10 other advanced intelligent species out there, I find it unlikely that none of the species would be interested in low T physics. It seems likely that to become an advanced species would require curiousity, so someone else out there is certainly do low T physics, and probably has been doing it for a 1000 years instead of 100.
Anyway, I think our differences come to down world view. I am an optimist when it comes to intelligent life in the universe, and that there are many wonders left for use to discover. You seem to be more a pessimist, who believes that humanity is "special." Well I think that you should remember this quote:
"Everything that can be invented has been invented."--Charles H. Duell, Commissioner, U.S. Office of Patents, 1899.
I think that we have a lot left to learn, and that someone else out there (whether we'll ever get to meet them or not) has probably already learned all that we know of physics.
Or stated another way, stick an isotropic distibution in a properly formed magnetic trap and you get an anisotropic distribution because of loss of particles with high speeds in the parallel direction;).
The point is other materials can probably become BECs and those other materials might require a lower effective temperature to become BEC. Besides which, as we refine our techniques for making BECs we'll be able to make bigger BECs where the effects of vacuum flucuations will be smaller, s oth effective temperatures will be smaller.
In summary, I'm not positing that the ETs will know some magical physics beyond QM that we don't know. I simply saying that the odds are that some one out there has been studying this stuff longer than us, so there techniques are more refined.
I'm confident that ETs exist based on the size on the size of the universe. Basically, take the Drake equation and enter a bunch of reasonable values. Is this a bullet-proof argument? Of course not, but then the best real proof of ETs would probably reproducible contact with them. Regardless, the existence of ETs is definitely a defensible argumenty.
As for natural processes that lead to temperatures below the cosmis microwave background temperature, there are at least of couple of obvious answers to that. One answer is that the CMB temperature is not exactly the same depending on which direction in the sky one measures. So if you consider the CMB temperature to be a single number, then any of those regions with a lower CMB temperature have matter at less than the CMB temperature. Admittedly, this is pretty much a cheat since you the CMB temperature should probably be considered a local value.
A stronger argument is that there probably are regions of space that are magnetically cooled below the local CMB temperature. All that is required for magnetic cooling is a mganetic field which will then preferentially trap particles with slower speeds parallel to the magnetic field. This is the same process that is at work in magnetic mirrors. Since magnetic fields are ubiquitous in space, its not too big of a leap of faith to assume that there are regions of space with higher than average magnetic fields that are far enough away from radiative sources that the magnetic cooling could bring the temperature below the CMB temperature. Regions behind intergalactic dust clouds could probably qualify.
Its very unlikely that anything we create is the "coldest matter in the universe", I'm sure that there are ETs out there somewhere that can cool stuff better than we can. And I wouldn't bet against there being natural processes that put matter in a colder states. There are certainly processes which results in matter cooler than the microwave background.
Bose-Einstein condensation has been around for
longer in the form of superfluid helium and superconductivity. What's new here is the fact is that alkali gases were turned into BECs. This allows for better study of BECs since the atoms of the gases are much more weakly interacting than atoms of superfluid helium-4 or solid superconductors.
But thousands of American civilians are already dead in this conflict, greater civilian losses than in any war in U.S. history.
Is the number of civilian casualties in this war really greater than in any previous US war? Does anyone have any references for this? I hadn't heard this before and to me this seems unlikely.
Surely some of the previous wars on US soil have had large number of civilian casualties. In the Revolutionary War there may not have been much collateral damage by direct bombardment, but certainly there must have been some deaths indirectly caused by the war - famine, etc. In the Civil War the similarly effects were present but to a greater extent due to campaigns like Sherman's march to the sea.
Probably the closest comparisons to prior conflicts can be made with the Indian Wars. During these conflicts between the US settlers and the Native Americans it is difficult to separate out the civilian casualties since much of the fighting was done by militias, etc. It should be possible to estimate civilians casualties for both sides in the Indian Wars by only counting women and children, and I would guess that the totals would be more than 6,000.
Of course the fact still remains that the number of civilian casualties that we've inflicted were much higher than those inflicted on us in the major wars of the 20th century. This is mostly a result of the fact that those wars weren't fought on American soil, but it bears consideration when trying to put the current conflict into historical context.
I'll agree with most of that (and I know the rocket equation, though I was too lazy to look it up before), but I don't think that the revised rule of thumb is the most important thing that you get out of that discussion. Instead, its that multi-stage rockets are quite useful;).
Well of course the exhaust velocity is measured relative to the engine. I was talking about the spacecraft velocity. And my point is that in order for your rule of thumb to hold there would have to be an absolute velocity (or a preferred frame). Since in space there is no preferred frame, this rule of thumb doesn't work. You can always pick the spacecraft's rest frame, so the engine never becomes inefficient by this rule.
Of course the rule makes sense when a rocket is in the atmosphere and the sensible frame to measure the rockets velocity is versus the atmosphere itself.
My favorite part of the video was at about 2:44.5 when a gentleman going through the revolving door appears to flick off the camera man. Seems pretty approriate.
Nice anti-emacs rant, Taco. You also mentioned you're impressed that vim can now edit files via ftp.
Taco didn't mention that vim can edit files over ftp, the submitter (LinuxNews.pl) did. If its hard to tell italic text from normal text I suggest that you get a new web browser since even in lynx its pretty easy to tell the distinction. HTH. HAND.
Re:Question to moderators
on
VIM 6.0 is Out
·
· Score: 1
Alas, there is no objective standard for humor.
This concern is why people continually ask for humor to have a separate rating. That way people who don't dig slashdot humor could filter it out.
Of course, your threshold sets so high that I doubt you'll ever see this post;).
Re:Screen dumps???
on
VIM 6.0 is Out
·
· Score: 2, Informative
Yeah, but vim does synatax highlighting!
So it more like, look a red v, a blue i, and a green m.
Woo hoo!
Favorite new feature
on
VIM 6.0 is Out
·
· Score: 2, Interesting
My favorite new vim feature is:hardcopy.
This feature lets you save to postscript (or print) versions of your file that look just like what's on the screen, including syntax highlighting. No more need to screw around with a2ps or enscript when you want to pretty-print code. Very nice. Thanks to Bram et al.
One other note: I thought a majority of web servers run a varient of linux.
Its very unlikely that the majority of web sites run Linux, at most the plurality of web sites run Linux. A majority of web sites might run some variant of Unix (including Linux). Apache may power the majority of web sites, but a lot of those Apache sites run on *BSD, Solaris, AIX, and even Windows. According to Netcraft
Linux does run a plurality of web sites followed by Microsoft, other, Solaris, and Unknown.
Also, as a rule of thumb, your engine becomes very inefficient once your spacecraft has exceeded its exhaust velocity. Chemical rocket engines have a maximum exhaust velocity of something like 3km/s - ion engines are more like 10-15km/s.
Does this rule of thumb hold in space? It doesn't seem like it would hold since there's no preferred frame of reference to measure the speed against. Is that 3 km/s relative to the Sun, the Earth, the solar wind, or Alpha Centauri? Since you can justify using any of those frames of reference to measure the velocity against, you can find many different speeds for the spacecraft, so the rule of thumb fails.
why is it that everytime a news source, such as slashdot, reports negativly on a politician, that if the political views of the politician coincide with that of the news source, that they fail to mention the politicians political party???
Uhm, this is not true for slashdot, at least. For an easy counter-example click on the link above for the previous
SSSCA story that was on slashdot (which is also linked above). In that story Senator Hollings is clearly identified as "(D-S.C.)". DMCA and its relatives are obviously not an issue that splits on a Democrat Republican basis, since the DMCA itself passed the Senate unanimously.
I wish that people wouldn't be so quick to jump to accusations of bias in regards to slashdot. 9 out of 10 times the so-called slashdot bias is due to poorly worded submissions from readers, not any conspiracy by the slashdot editors.
Also, the DMCA and its relatives are obviously not an issue that splits on a Democrat/Republican basis, since the DMCA itself passed the Senate unanimously.
They also must provide the code on a physical medium on request for no more than the cost of media and shipping; simply putting it up on ftp is not sufficient. In practice making it available by ftp may be acceptible if it means that nobody particularly wants to get the software on a physical medium, but the offer to provide the physical medium must be made.
I think you're incorrect about this. An ftp site should be fine, physical media is not required. If it were, Debian, for example, would be in violation, since Debian allows ftp access to all of the source in its distro, but does not sell CDs, floppies, etc. See section 3 of the GPL.
Slashdot Mirror
As for intellegent life in the universe, I would be surprised if there aren't billions of intelligent species out there. Even if there were only 10 other advanced intelligent species out there, I find it unlikely that none of the species would be interested in low T physics. It seems likely that to become an advanced species would require curiousity, so someone else out there is certainly do low T physics, and probably has been doing it for a 1000 years instead of 100.
Anyway, I think our differences come to down world view. I am an optimist when it comes to intelligent life in the universe, and that there are many wonders left for use to discover. You seem to be more a pessimist, who believes that humanity is "special." Well I think that you should remember this quote:
I think that we have a lot left to learn, and that someone else out there (whether we'll ever get to meet them or not) has probably already learned all that we know of physics.
Or stated another way, stick an isotropic distibution in a properly formed magnetic trap and you get an anisotropic distribution because of loss of particles with high speeds in the parallel direction ;).
In summary, I'm not positing that the ETs will know some magical physics beyond QM that we don't know. I simply saying that the odds are that some one out there has been studying this stuff longer than us, so there techniques are more refined.
As for natural processes that lead to temperatures below the cosmis microwave background temperature, there are at least of couple of obvious answers to that. One answer is that the CMB temperature is not exactly the same depending on which direction in the sky one measures. So if you consider the CMB temperature to be a single number, then any of those regions with a lower CMB temperature have matter at less than the CMB temperature. Admittedly, this is pretty much a cheat since you the CMB temperature should probably be considered a local value.
A stronger argument is that there probably are regions of space that are magnetically cooled below the local CMB temperature. All that is required for magnetic cooling is a mganetic field which will then preferentially trap particles with slower speeds parallel to the magnetic field. This is the same process that is at work in magnetic mirrors. Since magnetic fields are ubiquitous in space, its not too big of a leap of faith to assume that there are regions of space with higher than average magnetic fields that are far enough away from radiative sources that the magnetic cooling could bring the temperature below the CMB temperature. Regions behind intergalactic dust clouds could probably qualify.
Its very unlikely that anything we create is the "coldest matter in the universe", I'm sure that there are ETs out there somewhere that can cool stuff better than we can. And I wouldn't bet against there being natural processes that put matter in a colder states. There are certainly processes which results in matter cooler than the microwave background.
Probably the closest comparisons to prior conflicts can be made with the Indian Wars. During these conflicts between the US settlers and the Native Americans it is difficult to separate out the civilian casualties since much of the fighting was done by militias, etc. It should be possible to estimate civilians casualties for both sides in the Indian Wars by only counting women and children, and I would guess that the totals would be more than 6,000.
Of course the fact still remains that the number of civilian casualties that we've inflicted were much higher than those inflicted on us in the major wars of the 20th century. This is mostly a result of the fact that those wars weren't fought on American soil, but it bears consideration when trying to put the current conflict into historical context.
Or try Prosper which doesn't require any postprocessing.
1 eV = 1.6 E-19 J
So 500 GeV = 8E-8 J
That would be much for a macroscopic object, but is pretty impressive for a subatomic particle.
I'll agree with most of that (and I know the rocket equation, though I was too lazy to look it up before), but I don't think that the revised rule of thumb is the most important thing that you get out of that discussion. Instead, its that multi-stage rockets are quite useful ;).
Of course the rule makes sense when a rocket is in the atmosphere and the sensible frame to measure the rockets velocity is versus the atmosphere itself.
My favorite part of the video was at about 2:44.5 when a gentleman going through the revolving door appears to flick off the camera man. Seems pretty approriate.
Of course, your threshold sets so high that I doubt you'll ever see this post ;).
Yeah, but vim does synatax highlighting!
So it more like, look a red v, a blue i, and a green m.
Woo hoo!
My favorite new vim feature is :hardcopy.
This feature lets you save to postscript (or print) versions of your file that look just like what's on the screen, including syntax highlighting. No more need to screw around with a2ps or enscript when you want to pretty-print code. Very nice. Thanks to Bram et al.
The analogy isn't that bad since the crack of apache.org had nothing to do with the security of the apache web server
I wish that people wouldn't be so quick to jump to accusations of bias in regards to slashdot. 9 out of 10 times the so-called slashdot bias is due to poorly worded submissions from readers, not any conspiracy by the slashdot editors.
Also, the DMCA and its relatives are obviously not an issue that splits on a Democrat/Republican basis, since the DMCA itself passed the Senate unanimously.
Now Oppenheimer, he felt guilty for helping make the bomb.