Quite right. It's entirely fortytwoitous that the answer to the ultimate question is 7 times nine in base thirteen. I blame overuse of the Infinite Improbability Drive.
I'd phrase it as: it all depends on what units you prefer. The difference between joules and kilograms as units of mass-energy is in many ways similar to the difference between metres and parsecs as units of distance. They are just multiples of each other, and one unit is a very large multiple of the other.
To be serious: I'm not convinced its either cheaper or easier. If the impactor is nothing but a solid lump of metal with some terminal guidance on board that is going to be a lot cheaper and simpler than a robot big enough and smart enough to paint several square kilometers of asteroid surface. Admittedly, the observation probe has to be smarter and so more expensive.
What is not clear to me is why the observer has to hang around for so long and so far away. Why can't it just carry a radio beacon and hard-land on the asteroid after waiting for the impactor's immediate effects to dissipate. Thereafter the asteroid's position and velocity could be determined from earth-based observations with very high accuracy and for decades afterwards. That's pretty much what we're doing with the old Pioneer and Voyager probes.
So about Beagle 2, can Earth organisms survive several months in vacuum, high radiation and extremely low temperature for months?
Yes they can, as was demonstrated very convincing a while back when chunks of a Surveyor craft were returned from the moon by an Apollo crew. They were covered in microorganisms which had survived lunar conditions.
The average computer can crack a 128 bit RSA key in about a month.
Actually, the average computer can crack a 128-bit RSA key in about a minute. Assuming, that is, it's using an algorithm developed in the last twenty years or so. 128 bits is only 43 digits, and factoring 43-digit integers these days really is very easy.
in 1999, a beowulf cluster broke a 128 bit key in a matter of a few hours.
References please. This is a new one on me. What kind of key? At this size a RSA key, or a discrete log over the integers, is essentially trivial and a 3DES or AES key is essentially impossible, AFAIK. State of the art for the ECDLP (elliptic curve discrete logarithm problem) is still a few bits short - again, AFAIK.
In the realm of things the DLP over GF(p) is harder to solve then the IFP.
True, but arguably not significant. With the NFS, both problems have the same asymptotic difficulty. Further, the DLP isn't much harder than the IFP in practice. Solving instances of the N-bit DLP is approximately as hard as solving the IFP with N+30 bits.
Even harder is the DLP over eliptic (sic) curves.
Very much the case at present, though more and more curves are found to be vulnerable to variants of known attacks, and more attacks are being discovered all the time. There were some interesting papers at the ANTS-V and ECHIDNA conferences held earlier this month in Sydney.
NFS can be helped by distributed computing but the linear algebra can't. That's why the linear algebra is the real bottleneck and not the NFS if you had enough resources.
Not quite true. There are now implementations of parallel blocked-Lanczos which run very successfully on Beowulf clusters of relatively ordinary machines. The implementation I use was written principally by Peter Montgomery (who, incidentally, is an employee of Microsoft Research) and a cluster of 16 dual-proc PIII-1000 connected by gigabit ethernet yields performance comparable to the high-end Cray C90 which was used for many large-scale NFS factorizations over the last few years. We already know how to improve the implementation to the point where we expect to be able to double the speed or more.
i find it amusing that since silicon is in the same family as carbon people point it out to be an element that life could arise from, forgetting that the multiple-bonding ability of C is unique to this element...
Boron also has a multiple-bonding ability similar to carbon. The major problem for B-based life forms is the relatively low cosmic abundance of the element.
Silicon per se isn't particularly good for building large and complicated molecules out of, but in combination with oxygen it is excellent. Check out the structure of silicones and, for that matter silicate minerals. The latter frequently include magnesium and/or aluminium for added structural variety.
Remember, also, that organic chemistry is much more than the chemistry of carbon. C might be the essential element but there are very few molecules of biochemical interest which don't also contain hydrogen and most contain oxygen and/or nitrogen too.
It's not at all obvious to me that you can't build life-forms out of Si/O/Al/Mg, or out of boron, hydrogen and the first-row elements N, O and F.
If the probe is kept hot enough long enough it will indeed melt its way through. However, keeping it that hot for that long takes a lot of energy which has to be either carted all the way to Europa or has to be found in situ. A sufficiently large chunk of high-level nuclear waste might do it. Although this suggestion would reduce the waste problem here on earth slightly, I can't see the tree-huggers being very enthusiastic.
An alternative approach might be to punch through in one explosive event. Steer an appropriately sized cometary nucleus into Europa, wait for things to settle down a little and then dive into the relatively thin and slushy crater floor.
It's hard to tell whether Sumerian cuneiform is the oldest written language. Current opinion seems to be that surviving cuneiform is probably very slightly older than the oldest surviving Egyptian.
There are many inscribed artifacts which are older than either of these two examples but it's not clear whether they are "written language". Most of them seem to be ideograms similar in style and purpose to modern-day traffic symbols, smileys, logos and tally-marks.
Come on people., punched tape and cards really aren't a big problem. Lots of the hardware still exists and will be in museums for decades, if not centuries. Manuals giving encodings of many formats, real chewed-tree books, still exist and will do for a long time.
Even so, compared with the effort required to decode cuneiform from first principles, reading punch cards without either hardware or manuals would be a doddle --- always assuming that the cards still exist.
Exactly the same argument can be made for CDs, 9-track tape and so forth. As long as the written media exists and someone is sufficiently interested, it can very probably be read. The oft-quoted "unreadability" of the digital Domesday book is a misconception. It can be read; no-one is sufficiently interested to put the effort into reading it.
Indeed. I've found that cats can be trained to do anything they want.
To elaborate: cats like to be fed, to be clean and dry, to have somewhere comfortable to sleep and so on. They will quite easily learn behaviours which help them gain things they want. Meowing is only one mechanism among many. For example, several of our cats over the years (admittedly not all) have learned to have their cold, wet and/or muddy feet dried when they come in. They pop in through the cat-flap, head over to the old towel hanging in the kitchen and shout loudly. When one of us holds the towel down at cat level they back into it and expect to be dried. Our cats have learned a number of other responses which gain them benefits and others which stop us getting too annoyed at them. I doubt our cats are any smarter than average (most have come to us via rescue organizations and have an unknown ancestry) so my conclusion is that most cats are trainable.
The major difference between cats and dogs is that it's next to impossible to train a cat to do something *it* considers pointless.
True, protons don't fly apart but they don't have much charge either. I wrote "close to zero" on purpose. Free plutonium nuclei, on the hand, don't have close to zero charge and they do fly apart. However, you don't come across many free plutonium nuclei either because there are large numbers of loosely bound electrons lying around near other nuclei which the Pu nucleus can acquire, assuming it hasn't flown apart in the interim.
If these strangelets are big, and the models suggest that they are, then electric charge becomes important. Free protons and helium nuclei are common enough in nature, largely because their charges are close to zero.
Personally, I would expect highly charged strangelets to be exceedingly rare, not least because they could extract electrons from the vacuum and emit a positron at the same time. The mass-energy of the pair would come from the electromagnetic binding energy between the electron and strangelet.
"Uplets and downlets" are what we call "protons" and "neutrons.:-)
All quarks have charges which are \pm 1e/3 or \pm 2e/3. Doesn't stop normal matter being stable. I think the suggestion is that the strangelets contain enough up and down quarks and (presumably) electrons to make the aggregate close to zero charge.
There's at least one film, The Exorcist IIRC, that isn't available on video because the BBFC refuses to rate it.
Actually, YDRC. I don't know which film(s) is/are not available on video but The Exorcist is not one of them. I own a copy on tape but it's almost useless now my VCR is dying. More expense to get it on DVD...
Paul
Re:doesnt seem economical
on
Lunar Power
·
· Score: 1
Mercury doesn't keep one side permanently to the sun either.
I was present at this event. Despite what ZDNet claims, RMS did not use the term "PGP patent" but, correctly, described it as the public key cryptography patent.
The "transcript" is abbreviated which is acceptable, maybe even laudable, but it is also an inaccurate record of what RMS actually said --- which is not.
IMO, Stallman gave an extremely good talk aimed at those who were not experts on how the patent system works in practice. Far more eloquent than I'd anticipated from his previous writings on this and related subjects.
Read further down. NAI want to ensure that anyone who does buy it, doesn't lock them (NAI) out of future developments because PGP technology is used in other NAI products.
Selling to someone who goes on to screw your other products is markedly worse than maintaining the status quo.
Actually, "wog" is a derogatory word for any non-white person.
The first entry in the OED reads:
1. A vulgarly offensive name for a foreigner, esp. one of Arab extraction.
1929 F. C. BOWEN Sea Slang 153 Wogs, lower class Babu shipping clerks on the Indian coast. 1932 R. J. P. HEWISON Essay on Oxford 5 And here the Ethiop ranks, the wogs, we spy. 1937 F. STARK Baghdad Sketches 90 When I return, Nasir fixed me with real malignity in his little placid eyes. 'I knew she wanted me to go,' he said. 'I could see what she was thinking. They call us wogs.' 1942 C. HOLLINGWORTH German Just behind Me xiii. 258 King Zog Was always considered a bit of a Wog, Until Mussolini quite recently Behaved so indecently. 1944 [see COME v. 39e]. 1955 E. WAUGH Officers & Gentlemen II. 323 He turned up in western Abyssinia leading a group of wogs. 1958 Times Lit. Suppl. 11 Apr. p. vi/3 We have travelled some distance from the days when Wogs began at Calais. 1965 [see COMMIE]. 1982 J. SAVARIN Water Hole I. iv. 42 He hated Arabs... They were all wogs to him.
The phrase "Wogs begin at Calais" indicates a rather wider application of the term than the original usage.
There are 3 other definitions of "wog" in the OED, including "a germ or parasite, an insect, illness or disease", a C16 word which seems to mean "vague", and a verb "to steal, to pinch".
Slashdot Mirror
Quite right. It's entirely fortytwoitous that the answer to the ultimate question is 7 times nine in base thirteen. I blame overuse of the Infinite Improbability Drive.
Paul
No, your understanding is spot on.
I'd phrase it as: it all depends on what units you prefer. The difference between joules and kilograms as units of mass-energy is in many ways similar to the difference between metres and parsecs as units of distance. They are just multiples of each other, and one unit is a very large multiple of the other.
Paul
And when the first one dies, would burying it be a mammoth undertaking?
Paul
More accurate, perhaps, but not as much fun.#
To be serious: I'm not convinced its either cheaper or easier. If the impactor is nothing but a solid lump of metal with some terminal guidance on board that is going to be a lot cheaper and simpler than a robot big enough and smart enough to paint several square kilometers of asteroid surface. Admittedly, the observation probe has to be smarter and so more expensive.
What is not clear to me is why the observer has to hang around for so long and so far away. Why can't it just carry a radio beacon and hard-land on the asteroid after waiting for the impactor's immediate effects to dissipate. Thereafter the asteroid's position and velocity could be determined from earth-based observations with very high accuracy and for decades afterwards. That's pretty much what we're doing with the old Pioneer and Voyager probes.
Paul
Using "goto" within the context of a block is harmless, but also useless provided a rich enough set of control structures (if/then, while, for, etc.).
...
Very true, especially as you can write completely transparent code like this in a properly defined structured programming language.
label = 2;
while (label != 42) {
switch (label) {
case 1:
dostuff ();
label = 13;
endcase
case 14:
dootherstuff();
label = 666;
endcase
case 2:
domorestuff();
label = 93;
endcase
and so on
}
}
Paul
Yes they can, as was demonstrated very convincing a while back when chunks of a Surveyor craft were returned from the moon by an Apollo crew. They were covered in microorganisms which had survived lunar conditions.
Paul
Sigh. I really ought to check before relying on memory, rather than afterwards. A 128-bit integer actually has 39 decimal digits.
Paul
Actually, the average computer can crack a 128-bit RSA key in about a minute. Assuming, that is, it's using an algorithm developed in the last twenty years or so. 128 bits is only 43 digits, and factoring 43-digit integers these days really is very easy.
in 1999, a beowulf cluster broke a 128 bit key in a matter of a few hours.References please. This is a new one on me. What kind of key? At this size a RSA key, or a discrete log over the integers, is essentially trivial and a 3DES or AES key is essentially impossible, AFAIK. State of the art for the ECDLP (elliptic curve discrete logarithm problem) is still a few bits short - again, AFAIK.
Paul
True, but arguably not significant. With the NFS, both problems have the same asymptotic difficulty. Further, the DLP isn't much harder than the IFP in practice. Solving instances of the N-bit DLP is approximately as hard as solving the IFP with N+30 bits.
Even harder is the DLP over eliptic (sic) curves.
Very much the case at present, though more and more curves are found to be vulnerable to variants of known attacks, and more attacks are being discovered all the time. There were some interesting papers at the ANTS-V and ECHIDNA conferences held earlier this month in Sydney.
Paul
Not quite true. There are now implementations of parallel blocked-Lanczos which run very successfully on Beowulf clusters of relatively ordinary machines. The implementation I use was written principally by Peter Montgomery (who, incidentally, is an employee of Microsoft Research) and a cluster of 16 dual-proc PIII-1000 connected by gigabit ethernet yields performance comparable to the high-end Cray C90 which was used for many large-scale NFS factorizations over the last few years. We already know how to improve the implementation to the point where we expect to be able to double the speed or more.
Paul
Boron also has a multiple-bonding ability similar to carbon. The major problem for B-based life forms is the relatively low cosmic abundance of the element.
Silicon per se isn't particularly good for building large and complicated molecules out of, but in combination with oxygen it is excellent. Check out the structure of silicones and, for that matter silicate minerals. The latter frequently include magnesium and/or aluminium for added structural variety.
Remember, also, that organic chemistry is much more than the chemistry of carbon. C might be the essential element but there are very few molecules of biochemical interest which don't also contain hydrogen and most contain oxygen and/or nitrogen too.
It's not at all obvious to me that you can't build life-forms out of Si/O/Al/Mg, or out of boron, hydrogen and the first-row elements N, O and F.
Paul
If the probe is kept hot enough long enough it will indeed melt its way through. However, keeping it that hot for that long takes a lot of energy which has to be either carted all the way to Europa or has to be found in situ. A sufficiently large chunk of high-level nuclear waste might do it. Although this suggestion would reduce the waste problem here on earth slightly, I can't see the tree-huggers being very enthusiastic.
An alternative approach might be to punch through in one explosive event. Steer an appropriately sized cometary nucleus into Europa, wait for things to settle down a little and then dive into the relatively thin and slushy crater floor.
Paul
It's hard to tell whether Sumerian cuneiform is the oldest written language. Current opinion seems to be that surviving cuneiform is probably very slightly older than the oldest surviving Egyptian.
There are many inscribed artifacts which are older than either of these two examples but it's not clear whether they are "written language". Most of them seem to be ideograms similar in style and purpose to modern-day traffic symbols, smileys, logos and tally-marks.
Paul
Come on people., punched tape and cards really aren't a big problem. Lots of the hardware still exists and will be in museums for decades, if not centuries. Manuals giving encodings of many formats, real chewed-tree books, still exist and will do for a long time.
Even so, compared with the effort required to decode cuneiform from first principles, reading punch cards without either hardware or manuals would be a doddle --- always assuming that the cards still exist.
Exactly the same argument can be made for CDs, 9-track tape and so forth. As long as the written media exists and someone is sufficiently interested, it can very probably be read. The oft-quoted "unreadability" of the digital Domesday book is a misconception. It can be read; no-one is sufficiently interested to put the effort into reading it.
Paul
Indeed. I've found that cats can be trained to do anything they want.
To elaborate: cats like to be fed, to be clean and dry, to have somewhere comfortable to sleep and so on. They will quite easily learn behaviours which help them gain things they want. Meowing is only one mechanism among many. For example, several of our cats over the years (admittedly not all) have learned to have their cold, wet and/or muddy feet dried when they come in. They pop in through the cat-flap, head over to the old towel hanging in the kitchen and shout loudly. When one of us holds the towel down at cat level they back into it and expect to be dried. Our cats have learned a number of other responses which gain them benefits and others which stop us getting too annoyed at them. I doubt our cats are any smarter than average (most have come to us via rescue organizations and have an unknown ancestry) so my conclusion is that most cats are trainable.
The major difference between cats and dogs is that it's next to impossible to train a cat to do something *it* considers pointless.
Paul
True, protons don't fly apart but they don't have much charge either. I wrote "close to zero" on purpose. Free plutonium nuclei, on the hand, don't have close to zero charge and they do fly apart. However, you don't come across many free plutonium nuclei either because there are large numbers of loosely bound electrons lying around near other nuclei which the Pu nucleus can acquire, assuming it hasn't flown apart in the interim.
If these strangelets are big, and the models suggest that they are, then electric charge becomes important. Free protons and helium nuclei are common enough in nature, largely because their charges are close to zero.
Personally, I would expect highly charged strangelets to be exceedingly rare, not least because they could extract electrons from the vacuum and emit a positron at the same time. The mass-energy of the pair would come from the electromagnetic binding energy between the electron and strangelet.
Paul
"Uplets and downlets" are what we call "protons" and "neutrons. :-)
All quarks have charges which are \pm 1e/3 or \pm 2e/3. Doesn't stop normal matter being stable. I think the suggestion is that the strangelets contain enough up and down quarks and (presumably) electrons to make the aggregate close to zero charge.
Paul
NT4 to WXP? Or is that just 4.0 to 5.1? How about W98 to WXP?
I can see this is going to take a karma hit, but what the hell. Some people just don't understand irony.
Paul
Actually, YDRC. I don't know which film(s) is/are not available on video but The Exorcist is not one of them. I own a copy on tape but it's almost useless now my VCR is dying. More expense to get it on DVD ...
Paul
Mercury doesn't keep one side permanently to the sun either.
Paul
Coverage is lousy, despite what BT proclaim.
I live 5 miles (8km) due south of Cambridge city centre, supposedly the area with the highest number of geeks per square meter in all the UK.
My exchange is still not DSL-enabled and BT flatly refuse to suggest when it might be upgraded.
Stories of price cuts don't do much for those who can't get the service at any price.
Paul
I was present at this event. Despite what ZDNet claims, RMS did not use the term "PGP patent" but, correctly, described it as the public key cryptography patent.
The "transcript" is abbreviated which is acceptable, maybe even laudable, but it is also an inaccurate record of what RMS actually said --- which is not.
IMO, Stallman gave an extremely good talk aimed at those who were not experts on how the patent system works in practice. Far more eloquent than I'd anticipated from his previous writings on this and related subjects.
Paul
Read further down. NAI want to ensure that anyone who does buy it, doesn't lock them (NAI) out of future developments because PGP technology is used in other NAI products.
Selling to someone who goes on to screw your other products is markedly worse than maintaining the status quo.
Paul
Cute!
Clever, but not very intelligent.
Paul
Actually, "wog" is a derogatory word for any non-white person.
The first entry in the OED reads:
1. A vulgarly offensive name for a foreigner, esp. one of Arab extraction.
1929 F. C. BOWEN Sea Slang 153 Wogs, lower class Babu shipping clerks on the Indian coast. 1932 R. J. P. HEWISON Essay on Oxford 5 And here the Ethiop ranks, the wogs, we spy. 1937 F. STARK Baghdad Sketches 90 When I return, Nasir fixed me with real malignity in his little placid eyes. 'I knew she wanted me to go,' he said. 'I could see what she was thinking. They call us wogs.' 1942 C. HOLLINGWORTH German Just behind Me xiii. 258 King Zog Was always considered a bit of a Wog, Until Mussolini quite recently Behaved so indecently. 1944 [see COME v. 39e]. 1955 E. WAUGH Officers & Gentlemen II. 323 He turned up in western Abyssinia leading a group of wogs. 1958 Times Lit. Suppl. 11 Apr. p. vi/3 We have travelled some distance from the days when Wogs began at Calais. 1965 [see COMMIE]. 1982 J. SAVARIN Water Hole I. iv. 42 He hated Arabs... They were all wogs to him.
The phrase "Wogs begin at Calais" indicates a rather wider application of the term than the original usage.
There are 3 other definitions of "wog" in the OED, including "a germ or parasite, an insect, illness or disease", a C16 word which seems to mean "vague", and a verb "to steal, to pinch".
Paul