How does this stack up next to the transferrates of those fiberoptic telecomunication cables, like the ones they lay underwater and I beleave are used in the net's backbone?
Far ahead but not that far. From memory, the latest transoceanic cables must run at something like 160Gbps.
While I have to admit 2.56 Tb/s is darn impressive the article doesnt mention if this can be applied to currently existing fiber optic networks.
It does, implicitly: this uses advanced dispersion management (say, 10km dispersion-compensating fiber every 100km) and Raman amplification (power lasers launched backwards into the fiber every segment). If your cable isn't wired this way from the beginning, upgrading it would be more expensive than starting from scratch, I guess.
I seriously doubt my provider (twc) would be willing to just jump up and make large (read as: expensive) modifications.
You're speaking of a local bandwidth provider, which just won't ramp up to these bit rates in the near future, their customers won't generate so much traffic, and they could use several fibers instead of one anyway. This is for long-haul transmission, typically transoceanic.
Advances like this are interesting but how long will it take to "filter down" to us consumers?
Just wait for the transatlantic cables to be upgraded, you might feel it.
Normally I don't just post jokes all day long, but this one's too good, it exactly matches #2 of Why Usenet is Like a Penis:
In the long-distant past, its only purpose was to transmit information considered vital to the survival of the species.
Some people still think that's the only thing it should be used for, but most folks today use it for fun most of the time.
... and the survey is from the Christian Science monitor, even better!
NASA has already gotten this point. The MIP program (Mars In-situ Propellant) is aimed at exploring and developing the technology to produce fuel on Mars for the return journey.
True, but this is aimed at making CO and O2 from the atmosphere (or CH4 and O2 if you bring some hydrogen from Earth), which is not nearly as efficient as H2 and O2. Which doesn't make it altogether uninteresting...
Put lot's of cardbondioxide CO2 into the atomosphere and watch the planet temperature rise through the glass house effect.
Just a nitpick: Mars' atmosphere is already over 90% CO2, I think. So what you actually need to increase is its density.
Re:Mars as a refueling station ?
on
Lots of Ice On Mars
·
· Score: 4, Interesting
If there's H3 on Mars, however, the spacecraft only has to carry enough fuel to go TO Mars, and then get refuel there to come home.
It is unlikely that you can find tritium (H3) anywhere, it decays in a few years or decades. Perhaps you mean helium-3, and suppose that we have a He3-powered fusion-drive spaceship?
Anyway, we already have chemical rockets, for which water can be quite interesting (hydrogen-oxygen).
One more thought - if there's plenty of ice leftover, then Mars could be used as a "refueling station" for space flight further away than Mars.
Perhaps. But Mars isn't that small a planet, so mining near-Earth asteroids would probably be cheaper.
Water is what a colony will need most. If one can get it on-site, it can make huge mass savings on what one must bring in from Earth.
That, and the atmosphere (meteor protection, possibility to aerobrake when arriving) might make it easier to have a colony on Mars than on the Moon, even though it's much farther.
Be a major bummer to get there and find that there is nothing there.
I'd think that before selecting their destination, the colonists would make very careful observations, or more probably send an unmanned probe there first to check whether they can survive there. Now, if the destination star flares out mid-journey, that's another matter...
What strikes me is the sense of drama and tragedy if the on-ship culture panics or corrupts itself before it reaches the goal. Does anyone know of any stories that focus on that?
Yes, in a way, the second part of Stephen Baxter's Ring; most of the ship's population is more or less controlled by a few earth-born travelers, preserved with anti-aging nanotech, but one of them goes mad and mistakenly believes they have arrived 50years in advance.
Or maybe one of the later books in Clarke & Lee's Rendezvous with Rama series - at least I think so, I didn't go further than RamaII.
There is an interesting (and somewhat depressing) answer to the Fermi paradox in Stephen Baxter's "Space": interstellar spaceflight is reasonably practical, advanced civilizations do evolve and expand, and would potentially last a long time, except that before they have time to really spread out and develop StarTrek-like gadgets such as faster than light travel, defense shields, etc., a gamma ray burst occurs inside the galaxy, sterilizing everything within, and everybody starts over.
That would account for the lifetime part of the equation, I guess.
Quantum Mechanics has been known to be a time-trasnlation invariant theory. In layman's term, it means that you can run the clock backwards and everything is fine.
Same with classical mechanics, and more so, as QM has the "destructive measurement" hypothesis, that by merely measuring that an object is in a given state, you collapse any state superposition in which it might have been.
Besides, Statistical Physics and Thermodynamics have borrowed quite a lot from QM (particles being in given states among a number of possible ones, etc.)
However, we know the Thermodynamics 2nd law tells us that even *ideal* processes are essentially irreversible if we do work, i.e. waste heat is inevitable.
Yes, this comes from the fact that there exists a great many more possibilities that waste heat will be irrecoverably produced. It might stay in a usable form, just as you might open a bottle of ink under water, and the ink might flow out and then all crawl back into said bottle. It is just highly unlikely.
There is no need for an arrow of time at the microscopic level for that.
As for the paper itself, if I understand the summary correctly, it is ingenious but I'd look for a catch, such as the maser requiring at least as much power to function as that you can extract from the waste heat... Wouldn't that be annoying?
Oops, wait, hate to follow-up on my own post... I should have read the article more closely!
Neutrinos do not produce Cerenkov radiation, but the by-products of their colliding with something in the ice, electrons or muons, do, and that's how they are detected.
My understanding of this phenonemon is that the neutrinos are travelling faster than the speed of light in water or ice but not faster than c, the speed of light in vacuum. Cerenkov radiation is emitted in these circumstances.
I don't think so: neutrinos, as their name implies, are electrically neutral. Bearing no charge, they don't interact with electromagnetic fields, i.e. photons, so there can't be any Cerenkov radiadion emitted. It is not the same as with charged beta particles (electrons or positrons) blasting out of a nuclear reactor into water.
The neutrino detectors are using a completely different subatomic process, but my subatomic physics isn't advanced enough to tell what it is.
What I know is that they need a lot of matter (e.g. kilometer-thick ice) because neutrinos scarcely interact at all and can go through anything unnoticed. So the thicker the wall, the more chance there is that some of them will hit once in a while.
Actually it looks like it's right; say a person is 1.8m tall, 50cm wide and 20cm thick (about 6' by 20" by 8" for those unmetrified savages ). That would fit in 0.18 cubic meter, so we could have five people in a cubic meter with margin to spare. A cubic kilometer holding a billion cubic meter (1000 * 1000 * 1000), draw the conclusion...
you can convert the system back to ext2 in a second.. just mount it as ext2;-)
Not that simple actually. This will work but some filesystem manipulation tools could complain about "unsupported features" and even refuse to work.
The correct way to convert an ext3 filesystem back to ext2 is: "tune2fs-O^has_journal/dev/xxx; e2fsck-f/dev/xxx".
I will now retest ext3, since I can't believe this result.
I wouldn't be too surprised; ext2 by default does completely asynchronous writes, while ext3 is more reasonable and flushes data to disk before transactions commit.
You may want to mount your ext3 partition with the data=writeback option, which is closer in behavior to ext2, or alternatively mounting your ext2 partition sync. But ext3 has not been thought for high performance, reiserfs probably fares better.
That said, I'm still using ext3 on my Linux boxes rather than reiserfs as the latter has a history of being unexportable by NFS (something to do with inode management). Now they say it's OK, but I'd have to look a bit deeper.
Bush never cut the space station's budget... His administration simply agreed on the already-planned funding, but told NASA they wouldn't get a single buck more than that. Aren't they already several tens of billions over budget? (If I'm not mistaken, the planned cost was about $40billion and the current estimates are more like 80...)
And now they say they can't make it, due to an absolute failure to track costs. Giving them more money is encouraging them to soak more of it into their virtual monopoly on spaceflight. That said, not completing the space station is a violation of the US' international commitments.
How about calling for bids and letting a private company complete program? Preferably a small one - not Boeing and the likes, they're already the ones running the show...
I can't believe they used that scene from Independence Day as an example. It's the worst, most banal attempt at science fiction that hollywood has ever made.
Actually, with the way IT has been heading, I thought that scene was quite realistic; it might well happen in some distant future - with us humans as the invaders, of course.
How long til our targets 'sploit our mighty WindowsCE3000 mothership?
Do you mean just a single server to which users connect remotely,
or are all the client machines included? Are the latter homogeneous?
Are you starting from scratch or is there another infrastructure in
place?
If your only worry is a single machine, IMO there is no fundamental
difference with a home system, except that it has to be (even more)
solid (think redundant power supply, UPS, RAID, backups...), scalable
(think RAM, SCSI disks), and you have to pay (even more) attention to
potential local root holes. And use a system that works,
no fancy using the latest 2.5.1pre6 Linux kernel or 5.x-CURRENT BSD!
Think about how it will be accessed and don't cut corners on security
(use SSL for POP/IMAP if possible, favor SSH/SCP/SFTP over telnet/ftp,
use encrypted passwords for SAMBA). You may want to set up restrictions
on local users - quotas, limits on CPU/RAM usage, etc. You will
want to automate account creations: define different classes of users,
standard configurations, but also groups, mailing lists - manual
maintenance of those can be a major PITA.
OTOH, if you're also responsible for all the clients, then there's a
must read: Bootstrapping an architecture. Resist
any and all temptation, from yourself or others, akin to "100 users is
not enough to bother with automating everything, we'll just handle it
by hand", etc. I've been through this myself and regret all the time
lost installing, reinstalling systems, spending hours opening batches
of accounts, cleaning up old ones, and so on...
Computers are good at repetitive tasks, and this one
can and should be automated. Of course, keep solidity in mind; you don't
want all your network to halt because your upgrade server is stopped for
maintenance...
Finally, if you aren't starting from scratch, if you've just been
"promoted" sysadmin for 100 users with an existing network, then good luck.
Your best bet is to maintain the old infrastructure, set a new one in
parallel, and migrate users and machines one by one. But make sure to
interview many users and upset as little old habits as possible, otherwise
I hope your asbestos suit is ready!
OK, I found another article about this at SpaceRef.
Your data is correct, and they found a second planet beyond that one. Still, I'm not sure how a rocky planet could form with those two monsters nearby; it's the "far away from the star" in the WP article that confused me. Of course, they're comparing with those other star systems discovered recently, where gas giants are insanely close to the stars...
Wait a second here... If I understand correctly the table you link to, the planet you are talking about has almost 3 times Jupiter's mass, which is not really one where one would search life as we know it - except if it has satellites.
Furthermore, given that Jupiter orbits the Sun at 5.2AU, preventing planet formation between 2 and 5AU (cf. our asteroid belt), and that one is at 2.1AU from its star, I don't see how an Earth-like planet could be within that star's habitable zone, between 1 and 1.5AU.
In fact, I think the data from this table and that from the article are incompatible, even though the latter is scarce in hard numbers. Has the data been revised for the solar system of 47Uma since the table was written, or is it the article that has it all wrong?
How I wish that were true. How about looking at this April press release about the EU's latest directive on the subject, which member states now have 15-odd months to implement?
Slashdot Mirror
Far ahead but not that far. From memory, the latest transoceanic cables must run at something like 160Gbps.
It does, implicitly: this uses advanced dispersion management (say, 10km dispersion-compensating fiber every 100km) and Raman amplification (power lasers launched backwards into the fiber every segment). If your cable isn't wired this way from the beginning, upgrading it would be more expensive than starting from scratch, I guess.
You're speaking of a local bandwidth provider, which just won't ramp up to these bit rates in the near future, their customers won't generate so much traffic, and they could use several fibers instead of one anyway. This is for long-haul transmission, typically transoceanic.
Just wait for the transatlantic cables to be upgraded, you might feel it.
For a while I thought it was like the Pentium III...
Expected:1 Apr 2002
Description:A full release for the i386, Alpha, and sparc64 architectures.
Prerelease planned for April 1st? Hmmm...
Indeed. You'd have to replenish the atmosphere every few what, million years?
Now that's a challenge! The bacteria-seeding idea is an interesting one, although you'd probably be hampered by the lack of water.
True, but this is aimed at making CO and O2 from the atmosphere (or CH4 and O2 if you bring some hydrogen from Earth), which is not nearly as efficient as H2 and O2. Which doesn't make it altogether uninteresting...
Just a nitpick: Mars' atmosphere is already over 90% CO2, I think. So what you actually need to increase is its density.
It is unlikely that you can find tritium (H3) anywhere, it decays in a few years or decades. Perhaps you mean helium-3, and suppose that we have a He3-powered fusion-drive spaceship?
Anyway, we already have chemical rockets, for which water can be quite interesting (hydrogen-oxygen).
Perhaps. But Mars isn't that small a planet, so mining near-Earth asteroids would probably be cheaper.
Water is what a colony will need most. If one can get it on-site, it can make huge mass savings on what one must bring in from Earth. That, and the atmosphere (meteor protection, possibility to aerobrake when arriving) might make it easier to have a colony on Mars than on the Moon, even though it's much farther.
I'd think that before selecting their destination, the colonists would make very careful observations, or more probably send an unmanned probe there first to check whether they can survive there. Now, if the destination star flares out mid-journey, that's another matter...
Yes, in a way, the second part of Stephen Baxter's Ring; most of the ship's population is more or less controlled by a few earth-born travelers, preserved with anti-aging nanotech, but one of them goes mad and mistakenly believes they have arrived 50years in advance.
Or maybe one of the later books in Clarke & Lee's Rendezvous with Rama series - at least I think so, I didn't go further than RamaII.
There is an interesting (and somewhat depressing) answer to the Fermi paradox in Stephen Baxter's "Space": interstellar spaceflight is reasonably practical, advanced civilizations do evolve and expand, and would potentially last a long time, except that before they have time to really spread out and develop StarTrek-like gadgets such as faster than light travel, defense shields, etc., a gamma ray burst occurs inside the galaxy, sterilizing everything within, and everybody starts over. That would account for the lifetime part of the equation, I guess.
Same with classical mechanics, and more so, as QM has the "destructive measurement" hypothesis, that by merely measuring that an object is in a given state, you collapse any state superposition in which it might have been. Besides, Statistical Physics and Thermodynamics have borrowed quite a lot from QM (particles being in given states among a number of possible ones, etc.)
Yes, this comes from the fact that there exists a great many more possibilities that waste heat will be irrecoverably produced. It might stay in a usable form, just as you might open a bottle of ink under water, and the ink might flow out and then all crawl back into said bottle. It is just highly unlikely.
There is no need for an arrow of time at the microscopic level for that.
As for the paper itself, if I understand the summary correctly, it is ingenious but I'd look for a catch, such as the maser requiring at least as much power to function as that you can extract from the waste heat... Wouldn't that be annoying?
Neutrinos do not produce Cerenkov radiation, but the by-products of their colliding with something in the ice, electrons or muons, do, and that's how they are detected.
I don't think so: neutrinos, as their name implies, are electrically neutral. Bearing no charge, they don't interact with electromagnetic fields, i.e. photons, so there can't be any Cerenkov radiadion emitted. It is not the same as with charged beta particles (electrons or positrons) blasting out of a nuclear reactor into water.
The neutrino detectors are using a completely different subatomic process, but my subatomic physics isn't advanced enough to tell what it is. What I know is that they need a lot of matter (e.g. kilometer-thick ice) because neutrinos scarcely interact at all and can go through anything unnoticed. So the thicker the wall, the more chance there is that some of them will hit once in a while.
Actually it looks like it's right; say a person is 1.8m tall, 50cm wide and 20cm thick (about 6' by 20" by 8" for those unmetrified savages ). That would fit in 0.18 cubic meter, so we could have five people in a cubic meter with margin to spare. A cubic kilometer holding a billion cubic meter (1000 * 1000 * 1000), draw the conclusion...
Not that simple actually. This will work but some filesystem manipulation tools could complain about "unsupported features" and even refuse to work. The correct way to convert an ext3 filesystem back to ext2 is: "tune2fs-O^has_journal/dev/xxx; e2fsck-f/dev/xxx".
I wouldn't be too surprised; ext2 by default does completely asynchronous writes, while ext3 is more reasonable and flushes data to disk before transactions commit.
You may want to mount your ext3 partition with the data=writeback option, which is closer in behavior to ext2, or alternatively mounting your ext2 partition sync. But ext3 has not been thought for high performance, reiserfs probably fares better.
That said, I'm still using ext3 on my Linux boxes rather than reiserfs as the latter has a history of being unexportable by NFS (something to do with inode management). Now they say it's OK, but I'd have to look a bit deeper.
Bush never cut the space station's budget... His administration simply agreed on the already-planned funding, but told NASA they wouldn't get a single buck more than that. Aren't they already several tens of billions over budget? (If I'm not mistaken, the planned cost was about $40billion and the current estimates are more like 80...)
And now they say they can't make it, due to an absolute failure to track costs. Giving them more money is encouraging them to soak more of it into their virtual monopoly on spaceflight. That said, not completing the space station is a violation of the US' international commitments.
How about calling for bids and letting a private company complete program? Preferably a small one - not Boeing and the likes, they're already the ones running the show...
Actually, with the way IT has been heading, I thought that scene was quite realistic; it might well happen in some distant future - with us humans as the invaders, of course.
How long til our targets 'sploit our mighty WindowsCE3000 mothership?
If your only worry is a single machine, IMO there is no fundamental difference with a home system, except that it has to be (even more) solid (think redundant power supply, UPS, RAID, backups...), scalable (think RAM, SCSI disks), and you have to pay (even more) attention to potential local root holes. And use a system that works, no fancy using the latest 2.5.1pre6 Linux kernel or 5.x-CURRENT BSD!
Think about how it will be accessed and don't cut corners on security (use SSL for POP/IMAP if possible, favor SSH/SCP/SFTP over telnet/ftp, use encrypted passwords for SAMBA). You may want to set up restrictions on local users - quotas, limits on CPU/RAM usage, etc. You will want to automate account creations: define different classes of users, standard configurations, but also groups, mailing lists - manual maintenance of those can be a major PITA.
OTOH, if you're also responsible for all the clients, then there's a must read: Bootstrapping an architecture. Resist any and all temptation, from yourself or others, akin to "100 users is not enough to bother with automating everything, we'll just handle it by hand", etc. I've been through this myself and regret all the time lost installing, reinstalling systems, spending hours opening batches of accounts, cleaning up old ones, and so on... Computers are good at repetitive tasks, and this one can and should be automated. Of course, keep solidity in mind; you don't want all your network to halt because your upgrade server is stopped for maintenance...
Finally, if you aren't starting from scratch, if you've just been "promoted" sysadmin for 100 users with an existing network, then good luck. Your best bet is to maintain the old infrastructure, set a new one in parallel, and migrate users and machines one by one. But make sure to interview many users and upset as little old habits as possible, otherwise I hope your asbestos suit is ready!
OK, I found another article about this at SpaceRef. Your data is correct, and they found a second planet beyond that one. Still, I'm not sure how a rocky planet could form with those two monsters nearby; it's the "far away from the star" in the WP article that confused me. Of course, they're comparing with those other star systems discovered recently, where gas giants are insanely close to the stars...
Furthermore, given that Jupiter orbits the Sun at 5.2AU, preventing planet formation between 2 and 5AU (cf. our asteroid belt), and that one is at 2.1AU from its star, I don't see how an Earth-like planet could be within that star's habitable zone, between 1 and 1.5AU.
In fact, I think the data from this table and that from the article are incompatible, even though the latter is scarce in hard numbers. Has the data been revised for the solar system of 47Uma since the table was written, or is it the article that has it all wrong?
How I wish that were true. How about looking at this April press release about the EU's latest directive on the subject, which member states now have 15-odd months to implement?