Woah, what the heck makes you think you can rip off a portion of the cable? All you need to do is make sure that the interfacial adhesion is strong enough, and then when you climb, you can push down against it to climb upward.
What you're probably thinking of is that if you're gripping a cable along its sides, you're essentially trying to rip off the surface of the cable (via friction).
In order to avoid that, all you need to do is twist the cable through some rollers, and pull down on the cable to pull yourself up. Climbers do this when they twist a rope 90 degrees, and pull themselves up. This way, even if the surface has a low coefficient of friction, you can still climb easily.
Militarily, a self-interested US doesn't need a presence on the Moon. All they need is the ability to deny other nations such a presence, which is a trival job for existing missile technology.
The problem is that the US can't simply deny other nations such a presence. How could they? The first people that China lands on the moon will be for scientific reasons. Same thing with the lunar base. You simply can't blow up scientific missions - politically, that's suicide.
But from a purely military standpoint, it's STILL bad:
Your argument is essentially equivalent to "Militarily, the US doesn't need to have nuclear technology. They simply need to prevent other countries from having it, which is a trivial job for subversive intelligence."
(The last bit regarding subversive intelligence is a stretch, yes.)
The problem with both of the arguments is that if you fail, you're dead in the water - if someone DOES develop nuclear technology, suddenly no amount of spies or assassins will prevent them from wreaking havoc on your country, AND your enemy now has significant superiority over you. Instead of attempting to prevent them from getting nuclear technology, you could've been developing it yourself, and then been in a position of clear superiority over an enemy.
Same thing with a lunar base: if you fail with your existing missile technology, fundamentally, the base on the Moon can easily prevent strikes against it - they have tons of energy available to them from the Sun, and a much shallower gravity well to climb out of, which means that the cost to launch missles at the Moon from the Earth is much, much higher than to strike them down from the Moon. Then, you're sitting on Earth, militarily inferior, and having wasted a significant amount of time allowing your foe to improve their technology and reach an equal footing with you.
Not exactly a good plan.
Militarily, the ideal case is to develop the technology yourself AND prevent other countries from having it. If you have to choose one, though, you'd choose developing the technology yourself - the cost and risk is too high otherwise.
Sure, unless you can show me the ROI. And I think we can show an ROI for roads, can't we?
Roads that aren't used have an utterly terrible return on investment. Zero! So why would anyone build roads out in the middle of nowhere, where they'd never be used? That was the point - the Romans built roads across their entire empire, even where virtually no one lived.
Roads are enabling technologies: that is, they allow expansion and development to proceed much quicker than they would without roads. Even if you think that the roads will never be used, the roads turn the middle of nowhere into the middle of somewhere.
And if you want a direct ROI for space technologies, it's out there. Oh, dear God, is it out there. Just do a search for NASA technology spinoffs (or look here). How many examples do you want? Gemcutting tools, electronics, composite materials, infrared thermometers: all former NASA technology. There were conservative estimates that NASA had generated 7 times the money that was invested into it as returns into the GDP via technology improvements and new markets - so a ROI for taxpayers of about 700%. I think that would be considered a "good investment".
It's one thing to waste my hard-earned tax dollars to the tune of, say, ten billion. It's quite another to take several hundred of them, which is what enabling otherwise worthless views of Martian sunsets would run.
Ten billion? You'd be happy with ten billion? Great! With ~ten billion you could
Build a space elevator
Return to the Moon
Go to Mars (Zubrin's Mars Direct plan: probably a little optimistic costwise, but the point is that not everyone thinks it's hundreds of billions of dollars: Zubrin thought between $7 billion for private sector, JPL said $50 billion, for three missions)
As stated before, humans are lazy. So long as everything is easy, we won't learn anything. We'll never really work on radiation treatment technologies until it's necessary, for instance. Or ecological engineering : the real kind, trying to build a stable ecosystem.
C'mon. You're arguing against even $100 billion out of a multi-trillion dollar per YEAR budget. Space it over 5 years, and it's about 1% of the federal government's budget. That's a small price to pay to seriously kickstart several languishing economic sectors - it's not like they didn't pay nearly that amount to try to help the tourism industry, and it's not like the tourism industry has huge room for growth like space technology does.
The fact that this can be CGI simulated to the degree that you couldn't tell it from the "real thing" doesn't resonate with you, huh?
Well, that's a stupid comment. You could try to CGI simulate the things that Hubble sees, or have an artist draw them. They're about the same thing - artistic renderings, and they almost always tend to be less impressive than the real thing. We can't simulate things we have no direct experience with - otherwise we're simulating crap.
How would you know that the landscape you're simulating is correct? You don't have any data to contrast it with. The human eye is logarithmic in photoresponse, all sensors we currently have are linear in photoresponse.
Besides, show me a simulator that can simulate an entire atmosphere with uncountable numbers of micron-sized dust particles, and I'll be impressed.
If you can get bazillionaires to fork out the dought to stand on Amazonis Planitia and goggle at this sight you put so much stock in, then let's do it.
What a narrow-minded point of view. So I'm guessing that Hubble, in your mind, was a waste of money too? After all, all it produced to the public mind was a bunch of pretty pictures. Scientists know better, and scientists would know better that a Mars trip would generate more science than a few pretty pictures. But the fact is that Hubble likely generated more money and knowledge than it cost. By far.
That's the whole point of science - that you DO get a return on it, but that it's in ways you can't predict, and so therefore would likely (in a logical manner) never fund in the first place. Humans are short-sighted - nationally funded science programs are a method for counteracting that. Doesn't work THAT well (you generally have to come up with a bunch of bull which makes it sound like work you're doing is practically applicable) but it's better than nothing.
Analogy:
Rewind 2000 years.
"I don't see the reason for building roads all across the Empire. All our population is in one place! When it becomes important, then we can build the roads out in the outer regions. We've got plenty of time. I just don't want them spending MY tax dollars on this stuff now!"
Thankfully, no one said this - or if they did, the rulers realized it for what it was - short-sighted thinking. Ah, the benefits of dictatorships. Space travel is long-term planning. It will pay for itself - many, many times over. You just have to be patient.
Going to mars will not reveal exciting new facts about space to the general public.
Yes it will. It will show what Martian sunset and sunrise look like. From human eyes.
If Hubble proved anything, it proved the US public loves pretty pictures. Hubble rather quickly entered public consciousness as something that we were proud of (thus the MST3K the Movie joke "You killed the Hubble!") and major manned space travel would do the same.
I think you're being a little too cynical about the American public. If it were an international collaborative effort, I'd say you were being too cynical about the collective public, as well. It's true the support may not be there initially - but I think NASA'd find that support for manned space travel to another space body (like Mars) would have tremendous public support, once it started. Considering reaching Mars is a real long term effort, I think NASA'd only find that the public support would grow tremendously over time. I mean, c'mon, stuck on a ship with 3-4 other people for months on end? It's Fox's new reality show!
And for one, it's news about something that the US is doing that will go down in history that does NOT involve mindlessly blowing things up. People like feeling good about themselves (regardless of what current television portrays).
You're definitely correct though that there is no political reason to do it, and that is why it probably will not happen. I'm amazed that no one's written a "Congress simulator" yet - they're so predictable it's frightening. The only thing that moves them to action is fear of not being reelected.
The benefits from the memory subsystem will be offset by the fact that objects containing pointers will be twice as big as on IA32. That means objects could have twice the cache footprint and twice the memory bandwith requirements.
Except that pointers make up only a small fraction of the code footprint of an executable - most of it is ints, which still are 32-bit by default on x86-64. In general you can easily minimize the number of pointers in code by doing math (i.e., with 32-bit ints) on one base pointer.
The estimate is that code size will increase by about 10-15% on x86-64. Considering that the L2 cache is 1MB, as opposed to the standard size of 512k nowadays, it's a net win. Presumedly in the future they'll increase the cache size even more.
Supersymmetry and the Higgs boson are attempts to clean up mathematical holes, but they seem almost well motivated compared to the morass that is string theory.
Supersymmetry isn't an attempt to clean up a mathematical hole: it's an attempt to unify the strong nuclear, weak nuclear, and electromagnetic forces under one umbrella. Any group which covers all of those must necessarily have a supersymmetry. The Standard Model works just fine without supersymmetry - it's just that supersymmetry seems more elegant to people, so they work out its consequences. There's no reason whatsoever that a unified theory MUST exist. It's just that we'd really like it to.:)
In addition, the Higgs also isn't an attempt to clean up a mathematical hole. It's very, very necessary, and anyone who learns otherwise might want to read more about particle physics. We know that there exists a broken chiral symmetry (the SU(2) group in the Standard Model), and there has got to be a mechanism for providing that. The current 'best method' is the Higgs, and any other method will likely have to 'look like' the Higgs in a lot of ways. There wasn't any 'mathematical hole' unless you call 'lack of theory' a mathematical hole.
Now that's silly. String theory has a lot more direct connections to physics than number theory. I agree with your basic point that string theory is overhyped and tenuously connected with reality, but this kind of hyperbole does not help your case.
He's close. If he would've said "group theory" rather than "number theory", he would've been correct. Group theory is the backbone of a huge amount of modern physics, and there are still subtle points which need to be investigated, though I would never want to do them - hence the reason I am quite happy to let group theorists work it out.:)
Anyway, the whole situation isn't THAT different than the whole explanation for quark confinement (compressed flux tubes, and all that), the explanation for particle production by an inflating universe (relaxation of lowest-energy modes), or even Feynman diagrams as "particle graphs" - none of them are entirely correct, but they're all 'suggestive', and are easy to understand intuitively. I will agree that the Hawking radiation example is a little too specific for me. I think I'd rather say something like
"caused by the disparity in particle/antiparticle generation near the event horizon, due to the formation of distinct regions in a previously smooth particle/antiparticle sea" - worded more eloquently, of course, but I think that's the issue.
The problem is that the Hawking radiation description actually does contain some real physics there. They're talking about a particle and an antiparticle being generated (some combination of a adagger and adagger a), and one of them being caught in the region of curved spacetime (a adagger/adagger a are different in two different reference frames), resulting in particle generation (because N = adagger a - a adagger is now different).
One caveat, as well: ghost particles aren't virtual particles. They're ghost particles. A virtual particle is a normal particle which is off-mass-shell - it still has all of its correct quantum numbers, just bad energy. Ghost particles don't have correct spin/statistics relation, and therefore aren't particles at all. If memory serves, ghost particles are never external legs in a complete Feynman diagram, which means they're always virtual ghost particles, but they're not virtual particles. Just a bit of a nitpick. (And I didn't think that there -was- a way to solve NAGTs perturbatively without the use of Fadeev-Popov ghosts).
It comes from the fact that in curved spacetime there is no natural choice of time coordinate and so you can't distinguish between positive and negative energy modes meaning that you can't distinguish properly between creation and annihilation operators.
The answer to that's not so clear: it's true the number operator in different (curved) reference frames is different, since the annihilation/creation operators are different. However, saying that has nothing to do with pair-production isn't exactly correct - after all, the zero-point energy, in some cases, generates from normal-ordering (a adagger + adagger a) (in others from symmetry breaking, but I think the same argument applies). You could in fact, define ZPE = integral (adagger a - a adagger), which gives you something like ZPE = integral (N - Ndagger). ZPE density would just be N - Ndagger, and could be interpreted as the number of virtual particle pairs created per unit space per unit time.
Bleh, that's hard to understand without writing things down. Anyway, the point is that if you consider "ZPE" to be "all of the virtual particle pairs in the quantum vacuum", then, for instance, Unruh radiation (and likely Hawking radiation as well) can be explained 'somehow' via virtual particle pairs, as Unruh radiation is just going to be the difference between N in one reference frame and N in another reference frame, hence ZPE in one reference frame, and ZPE in another reference frame. I mention Unruh radiation because it'd be harder to explain 'canonically' than Hawking radiation, though I can somewhat see a way to explain it.
What the actual 'canonical explanation' is, that's a different story. It doesn't tremendously matter, as virtual particle pairs don't appear as two little balls zipping through space at all. It's just a picture for the minds' eye. However, basically saying that the curved spacetime produces a change in particle pair production/destruction rate from one reference frame to another, resulting in a generation of particles, that's perfectly valid, and so, the pair-production argument isn't totally bunk.
Well, there are several reasons Progress slammed into Mir. The source that I had heard (granted, on the Discovery channel) said that one of the cosmonauts saw the problem, and relayed an incorrect direction because he didn't orient himself correctly.
Granted, still not a computer's fault. But proof that navigating in 3D is difficult.
OK, even assuming Chris Sontag (who's rapidly replacing McBride as "Biggest Idiot I've Ever Seen In Charge Of Something He Has No Idea About") honestly intended the BPF code to be an 'example', he missed the point.
It's not obfuscated code. Not at all. It's a clean room implementation, and if he doubts it, he can go to the door of the person who wrote it, and kiss his ass.
Second, they argue that the malloc() implementation is still valid, even after Linus says "well, it was removed" - ignoring the screams by the damned authors of the code saying "Screw off, SCO, it's OUR code, we wrote it, go the hell away."
For everyone out there that thinks there might be something to their claims, there isn't. They're idiots. There's absolutely nothing intelligent that they've pointed out at all, and they've simply proved that they're really attempting a shell game. No, no, look in the other hand. That's where we've got the infringing code!
(Note to all nitpickers: yah, yah, all the overhead associated with running a binary MAY make it quicker to run on a massively parallel machine. Blah. You get the point.)
You can't parallelize 1 operation. On a P4 that 1 operation would get done in what, 1 clock cycle? Same for the ES, and the clock speed's higher on the P4, so the wall time is shorter for the P4 by a fraction of a nanosecond. Parallelizable code is actually quite specific, and there are a lot of cases of non-parallelizable code.
You know, I replied to my above message but didn't post it, because I figured "nah, everyone will know what I mean".
I forget what the grammatical mistake is called, but anyway - the "We've simply never done it" referred to 20 or 30, not 2. Yes, we've done 2. 2 is hard. Not easy. Hard. That's why the Progress slammed into Mir once.
Sounds fine, but is formation flying really going to be the big challenge 20 years from now when we put a very-long-baseline replacement for Hubble up?
The replacement for Hubble is the James Webb Space Telescope (also referred to as the NGST, for Next Generation Space Telescope). This is likely to be its replacement, the Terrestrial Planet Finder.
Anyway, regarding formation flying: Have you ever done it? Fact is, it's hard to get -two- spacecraft to move into relative position to each other, much less 20 or 30. We've simply never done it, and the TPF is NOT the only place we'd want to do it. A gravitational wave telescope, for instance, would be wonderful in space (LISA, I believe, is/was its name) but the concerns were always "can we get satellites to stay within a small fraction of a wavelength of each other?"
This project is designed to say "Yes, yes we can."
Wrong. Getting to the moon is about as expensive as getting to Mars, more or less, largely because Mars has an atmosphere that you can use to brake against for free. Only a fool would go to the Moon, stop there, then launch off again to go to Mars[.]
Hm. True, but then you say...
The Moon is largely made up out of minerals we are quite familiar with here on ol' Terra[.]
Even more true! But then you miss the obvious - it shouldn't be that hard to flat out build spacecraft on the Moon (after all, they've got iron, silicon, etc.), and it's virtually free to launch craft into LEO/GEO/etc. from the Moon's surface (it's about 2 km/s delta-V or so needed, AND there's no atmosphere, so even something like an ion drive will kinda work - you'd still need a bit of an initial boost so you don't run into hills, etc., or a magnetic rail launcher).
If it wasn't for R&D costs and the pathetic state of automated factory technology (and/or the lack of a human base on the moon), fundamentally, you're better off building one factory 'craft, sending it to the Moon, and having it build 20 GEO satellites and launching them into GEO from there, rather than launching 20 GEO craft from Earth.
Note that I'm not talking about the current state of affairs - no way. But fundamentally, the Moon is a nice 'spacecraft launch base', but only if the spacecraft are built there.
Plus you have the added benefit of you don't have to pay for any of the materials. Though strip-mining the moon might piss some people off. Not me, though!
Even if the Moon would end up lacking certain critical materials (it is apparently short on carbon, though it's difficult to say what the subsurface holds), it's probably still a winning situation to ship up small amounts of the missing 'critical materials' (to make steel, for instance) as the materials available on the Moon likely would make up the bulk of the weight of the craft. You also have the added benefit that assembly in 1/6 gee is probably significantly easier for certain tasks than zero gee (and harder for others, but at least if you can't permanently lose bolts by bumping them:) ). With enough lunar infrastructure, a construction yard would make it EXTREMELY easy to build things on the Moon. You then have the additional benefit of not needing to put them through the utter hell of launching off of Earth. Most spacecraft failures and problems come from launch stress problems, and launch from the Moon could be (basically) as gentle as you want.
In any case, don't discount out the Moon as a launch base - you're definitely right that it's stupid to use it as a stopping point. It's NOT silly to use it as a future launching base and construction/assembly yard.
The delta-v quoted by your source is far lower than the delta-v needed to get into a Hohmann transfer orbit even from free space in a circular solar orbit at Earth's radius (which the C3=0 orbit is the equivalent of). As the Hohmann orbits are the lowest energy transfer orbits that don't require slingshots from other bodies, I question the values on that figure.
Ah, there's your problem. The C3=0 orbit is NOT a circular orbit at Earth's radius. It's a parabolic orbit with Earth at its focus, which necessarily can NOT be a circular orbit about the Sun at Earth's radius. A parabolic orbit means that at infinity, it will have no velocity relative to the Earth, which means, if the craft traveled to infinity, it would then have the equivalent orbital velocity of Earth. Problem is, it never reaches infinity, as it's not a two-body system, since the Sun's there.
If you want a spacecraft to be in a circular orbit at Earth's radius, well, it doesn't have to do anything - just stay home. It already is in one.:) After it lifts off, depending on the direction, it is doing two things - first, it is escaping from Earth's gravity, and second, it is changing its orbit. You don't have to "add" the escape velocities onto the necessary orbital delta-V. If you wanted it to actually reach a circular orbit, that takes a lot more work, actually!
This is the problem when you're doing "you need to add an extra 5.03 + 2.38 km/s" - you're adding the Lunar escape velocity and the Martian escape velocity, which you do not need to do, because you're not exactly going to infinity. On the return, you can easily aerobrake in Earth's atmosphere as well to enter lunar orbit.
Also don't forget about aerobraking! No matter what, any time you approach a planet (even entering lunar orbit! you can always place your perigee inside Earth's atmosphere with clever timing!) if you need to slow down, it's free.
And if you don't like that site, how about here, which shows that Deimos is more accessible than the Moon (and shows a delta-V from Mars surface to Lunar surface of 8.0 km/s, not 13.0 km/s).
Or here, where you'll note that "LEO to Mars" is a delta-V of 4.8 km/s, not the 5.6 km/s you're claiming - this is because, of course, it's in LEO, and therefore has some orbital velocity about Earth (and is therefore traveling at -greater- than Earth's orbital velocity at certain points).
I can continue to give examples if you want - the point is that from the Moon, it's easier to get to Mars and back than it is to get to Earth and back.
The easiest way to think about this is simple: You do not need to actually escape Earth orbit in order to reach Mars. A highly eccentric orbit can include both Earth and Mars (if both were stationary, obviously - they're not, so you can't orbit them, but you can of course use that path to transfer between them), and so must necessarily take less energy than the escape velocity of Earth+the escape velocity of Mars (which reaches Mars by going through infinity).
Interestingly enough, Hohmann transfers are not lowest energy. Google for "interplanetary superhighway", which is a relatively recent discovery. Really does suck that the 3-body system isn't analytically solvable...
In order to get to the moon in the first place, you need to have almost completely escaped the Earth's gravity, so it doesn't help for launch of things that are originally from Earth. Best approach for that is to launch them to as _low_ an orbit as you can (so as to minimize delta-v required of high thrust, low-Isp drives), and to spiral the rest of the way out over a period of months using a low thrust, high-Isp drive.
Correct. But it does help for things that are going to Earth. That is, a base on the Moon would be ideal as a place for docking spacecraft that shuttle back and forth between places (like mining the asteroids, for instance). The advantage is that you don't want to bother lifting the 'craft up Earth's gravity well when you don't need to, and of course, if you're transferring things TO Earth FROM the Moon, that's virtually free.
This only applies if the craft MUST dock, because even the Moon has a gravity well. If it can just jettison things, then hell, very clever orbital mechanics wins over the Moon any day.
But, it COULD be useful. It would also be more useful as a manufacturing plant for Earth satellites - launch cost of 2.3 km/s to GEO, rather than 13.8 km/s.
This turns out not to be the case, as you need a lot of delta-v to travel from Mars's orbit to Earth's (the sun's gravity well is deep).
Huh? Mars's orbital velocity is ~24 km/s, Earth's is 30 km/s. That's 5 km/s difference, and escape velocity from Earth is 11 km/s, and Mars's escape velocity is 5 km/s. As far as I can tell, if you escape from Mars's orbit, you'll basically fall back to Earth's orbit, free. I'm just doing back-of-the-envelope calculations, but it seems smaller to me (yah yah, I'm ignoring tons of orbital dynamics, but the points are ~roughly valid). I think the parent poster is correct.
Actually, a brief search online finds that I'm right, as shown here. The DV from Mars C3=0 orbit to Earth C3=0 orbit is 0.9 km/s - virtually nothing! delta-V from Earth's surface to lunar surface is 9.7+2.5+0.7+0.7+1.6 = 15.2 km/s. Delta-V from Mars surface to Lunar surface is 4.1+0.9+0.3+0.2+0.9+0.7+1.6=8.7, which is almost a factor of 2. I think more clever methods could probably be derived to lower that to less (using Phobos or Deimos for a gravity handle, if they're rotating in the proper way... I can't think off hand).
The Sun's gravity well is deep, but 1/r^2 wins every time.
They do, it's whatever kernel Red Hat are shipping, you can get the source. ISVs need some common point, or you are going to have Oracle requiring kernel A and SAP/Veritas/etc. requiring kernel B which aren't mergable.
Bullshit. Red Hat's kernel isn't static - it moves just like any other. So if one says "You must use Red Hat 7.3" and another says "You must use Red Hat 8.0", you could be screwed in any case.
Ah, now you're going to say "well, they'll just say 'the most current Red Hat' and keep it current!" except that this is identical to saying "the most recent Linux kernel" and keeping it current, except that checking against the most recent Linux kernel would be less work than installing a new version of Red Hat.
Well unless they call "chkconfig", or "service" or, configure some file in/etc/sysconfig/ or require Java. I suppose they could just ship their own distro.... yeh just what I want: 15 different distros. to manage, I'm running Oracle/Veritas/WebSphere on this box and SAP/Streams/PowerPath on that one over there.
That's right. Because the source code to chkconfig or service isn't available at all. Oh yeah, that GPL thing. Besides, what the hell are they doing messing with files in the system configuration? And no, that isn't an idle comment - there is no reason to be puddling around in some vendor-specific files. Install a script in/etc/init.d, a configuration in/etc/foo.
Java? Last time I checked Java wasn't Red Hat specific, and it is relatively trivial to figure out what Java runtime is on a system. Give me a break. This is what "configure" scripts are for. If a company says "Red Hat Only!" then they don't understand computers and/or the operating system they're writing for. And that's ALWAYS dangerous.
Oh sure, you can just "apt-get update" to mirror the latest stable (or however), but it you're looking for specific sets of code, in specific versions, then just rattling off a quick command to "just work" and get all the most current stuff isn't exactly an option, no? You still have to put together at least a package list to grab. Can do the same thing with RPMs.
Huh? You don't need to put together a package list to grab - not if you're using the latest releases from Debian. Then they already exist for you.
apt-get update apt-get upgrade
done.
There are two points with this:
In Red Hat, up2date, urpmi, work similar to this. Granted. But...
Most.debs found on the Web will work with any Debian (dpkg) based system. The same can't be said for an RPM based system (ever try to install mdk RPMS on a Red Hat machine?).
With Debian, I can do this forever. Ad infinitum. Some people are still running a system that was first installed five years ago.
With Red Hat, you can't - a Red Hat 6.2 distribution has to be 'upgraded' to a 7.0 distribution. This is what makes it easy to upgrade. I never have to worry about Hey, should I upgrade to Debian 3.0? Hell, I didn't even KNOW when Debian 3.0 came out - I just noticed "wow, my login changed. That's neat!"
I've done it quite a few times rebuilding a specific machine state when I've been tinkering and not quite understanding what I'm doing with the code I'm massaging.
The point is I don't want to do ANYTHING. It's easy enough - tell the user to install all custom apps under ~ and ~/lib/, etc., and then I don't even need to bother about doing backups of the main system, nor even a package list, because it'll take no time to actually have it rebuild everything.
So I'm guessing you've got a Red Hat house, right? How many times have you reinstalled Red Hat - even to 'upgrade'? Once? That's too much. There is ONE reason to reboot a machine - to change the kernel. Other than that, there is absolutely no good reason to reboot at all. Worst comes to worst, switch to single-user, then kick back up to multi-user.
It was when it was suggested that we need to upgrade all 5 of our then-Red Hat boxes to RH7.x that I said "this is incredibly dumb. There's got to be a better option". There was.
Look, it's not deb vs. RPM (don't say apt vs. RPM - APT is not a package format). It's 'standards' vs. 'thrown together haphazardly'..debs are good packages, consistently..debs in the Debian repository are VERY good. The same's just not true for RPMs, and anyone who doubts me can go look at rpmfind.net, and see something like 40 different versions of the exact same package.
The problem is that for Red Hat, there are more 'badly behaved' RPMs than there are 'badly behaved' packages in Debian - especially Debian stable.
The other thing is that for Debian, I do not need to set up a local source or package repository. I use one of the Debian mirrors, and poof, everything's good. If you use stable (which is NOT that out of date, regardless of what people say) then when a package updates, big deal - it'll STILL just work.
Those 7-10 identical PCs just run Debian. Nothing special. Nothing amazing. Just Debian.
Yah, it took about 15 minutes of poking around apt-get's man page to find how to upgrade only the security packages by default (you CAN do this - apt-get update; apt-get upgrade;apt-get update with the options to select a different APT config for the first two, and create one that only has the security servers) - but it wasn't that hard, and now we've got automated security updating. Works for me!
I can not STAND people that say "Oh, well, it won't run on anything but Red Hat". Give me a break. The operating system is called Linux, not Red Hat (OK, maybe GNU/Linux). Linux defines the API and the application interfaces (ditto GNUification), and quite simply, everything that runs on Red Hat will run on Debian.
Period. Wackos who tell you "oh, maybe it's a problem with Debian" simply don't understand the way computers work. That's why I can't stand that Oracle won't support anything except Red Hat. That's silly. More than silly. They wrote a program, that works under Linux, not under Red Hat. If it's kernel version dependent, state the kernel versions it was tested under - or better yet, give the source tree! (wow!) If it's library dependent, give the library versions. If it's library dependent, static link the damned thing. There is nothing that runs under Red Hat that can't run under Debian.
You know what someone really needs to do? Write a bunch of scripts that let one distribution 'play' as another one, so you can just reboot and launch as a Red Hat clone, Debian clone, etc. (if you don't need a new kernel version, you don't need to reboot). It can't be that hard. That way when someone asks you what type of Linux you're using, you can say "What type would you like it to be, so I can then prove to you that you're being an arrogant prick and it really IS your problem?"
One of the nice things regarding Debian is that basically all it is is a set of installed packages - no extra magic, basically. Creating a local mirror is as easy as creating a local APT source and storing all the packages there, and then instead of running apt-get update on the machines, run apt-get update on the mirror PC, which updates all of them. If the mirror PC works fine, then copy all the packages to the local APT source, and boom, you're fine. The details here are sketchy, yah, but it's an easy problem.
Regarding the security patches, I honestly don't know what problem you have with them: maybe Debian has really improved security support since then, but if you check Debian's page, you'll see that security.debian.org's response time is just as fast as any of the other major distros. There are several bugs for which Debian had a package that fixed the problem first (the SSH bug that required privsep comes to mind).
And honestly, I have NO idea what problem you had where a package broke something badly, unless you were running unstable. In my experience, Debian's packages are FAR less likely to break a system than some random less-0.4.3-mdk3-only-work-on-a-sunday.rpm. The few problems I've had were dumb problems that were immediately obvious (and in fact were stupid user errors, as I forced an upgrade of a package without forcing the upgrade of its neighbors).
I've never been happier since I converted my lab's PCs to all Debian. Yah, it's small, but I have to handle something like 7-10 PCs, and having them all in almost exactly the same state (which is far harder to do in Red Hat than in Debian) is SO nice.
I mean, the main reason Debian stable is farther behind than everyone else is because they take their time. When they mean stable, they really really mean stable - not just stable as in 'won't crash', but stable as in 'will do what it says it does'.
Plus, like the complete bastards that they are, male mosquitos are pollinators! Only the females are the bloodsucking disease spreading type.
Honestly, wiping out mosquitos probably wouldn't hurt birds, bats, spiders, frogs, etc. But the lack of pollinators would really screw certain plants up, which could do bad things.
Plus the ever-important thing to remember is that mosquitos are only a vector. They're not truly the problem - if you remove mosquitos by killing them all, something new will fill that niche, and probably rather quickly, and poof, malaria all over again. Life likes to evolve to new niches.
The better thing is of course to cure the disease, because, as you said, there is little to no beneficial role in human diseases anymore.
Slashdot Mirror
Woah, what the heck makes you think you can rip off a portion of the cable? All you need to do is make sure that the interfacial adhesion is strong enough, and then when you climb, you can push down against it to climb upward.
What you're probably thinking of is that if you're gripping a cable along its sides, you're essentially trying to rip off the surface of the cable (via friction).
In order to avoid that, all you need to do is twist the cable through some rollers, and pull down on the cable to pull yourself up. Climbers do this when they twist a rope 90 degrees, and pull themselves up. This way, even if the surface has a low coefficient of friction, you can still climb easily.
Militarily, a self-interested US doesn't need a presence on the Moon. All they need is the ability to deny other nations such a presence, which is a trival job for existing missile technology.
The problem is that the US can't simply deny other nations such a presence. How could they? The first people that China lands on the moon will be for scientific reasons. Same thing with the lunar base. You simply can't blow up scientific missions - politically, that's suicide.
But from a purely military standpoint, it's STILL bad:
Your argument is essentially equivalent to "Militarily, the US doesn't need to have nuclear technology. They simply need to prevent other countries from having it, which is a trivial job for subversive intelligence."
(The last bit regarding subversive intelligence is a stretch, yes.)
The problem with both of the arguments is that if you fail, you're dead in the water - if someone DOES develop nuclear technology, suddenly no amount of spies or assassins will prevent them from wreaking havoc on your country, AND your enemy now has significant superiority over you. Instead of attempting to prevent them from getting nuclear technology, you could've been developing it yourself, and then been in a position of clear superiority over an enemy.
Same thing with a lunar base: if you fail with your existing missile technology, fundamentally, the base on the Moon can easily prevent strikes against it - they have tons of energy available to them from the Sun, and a much shallower gravity well to climb out of, which means that the cost to launch missles at the Moon from the Earth is much, much higher than to strike them down from the Moon. Then, you're sitting on Earth, militarily inferior, and having wasted a significant amount of time allowing your foe to improve their technology and reach an equal footing with you.
Not exactly a good plan.
Militarily, the ideal case is to develop the technology yourself AND prevent other countries from having it. If you have to choose one, though, you'd choose developing the technology yourself - the cost and risk is too high otherwise.
Roads that aren't used have an utterly terrible return on investment. Zero! So why would anyone build roads out in the middle of nowhere, where they'd never be used? That was the point - the Romans built roads across their entire empire, even where virtually no one lived.
Roads are enabling technologies: that is, they allow expansion and development to proceed much quicker than they would without roads. Even if you think that the roads will never be used, the roads turn the middle of nowhere into the middle of somewhere.
And if you want a direct ROI for space technologies, it's out there. Oh, dear God, is it out there. Just do a search for NASA technology spinoffs (or look here). How many examples do you want? Gemcutting tools, electronics, composite materials, infrared thermometers: all former NASA technology. There were conservative estimates that NASA had generated 7 times the money that was invested into it as returns into the GDP via technology improvements and new markets - so a ROI for taxpayers of about 700%. I think that would be considered a "good investment".
It's one thing to waste my hard-earned tax dollars to the tune of, say, ten billion. It's quite another to take several hundred of them, which is what enabling otherwise worthless views of Martian sunsets would run.
Ten billion? You'd be happy with ten billion? Great! With ~ten billion you could
As stated before, humans are lazy. So long as everything is easy, we won't learn anything. We'll never really work on radiation treatment technologies until it's necessary, for instance. Or ecological engineering : the real kind, trying to build a stable ecosystem.
C'mon. You're arguing against even $100 billion out of a multi-trillion dollar per YEAR budget. Space it over 5 years, and it's about 1% of the federal government's budget. That's a small price to pay to seriously kickstart several languishing economic sectors - it's not like they didn't pay nearly that amount to try to help the tourism industry, and it's not like the tourism industry has huge room for growth like space technology does.
The fact that this can be CGI simulated to the degree that you couldn't tell it from the "real thing" doesn't resonate with you, huh?
Well, that's a stupid comment. You could try to CGI simulate the things that Hubble sees, or have an artist draw them. They're about the same thing - artistic renderings, and they almost always tend to be less impressive than the real thing. We can't simulate things we have no direct experience with - otherwise we're simulating crap.
How would you know that the landscape you're simulating is correct? You don't have any data to contrast it with. The human eye is logarithmic in photoresponse, all sensors we currently have are linear in photoresponse.
Besides, show me a simulator that can simulate an entire atmosphere with uncountable numbers of micron-sized dust particles, and I'll be impressed.
If you can get bazillionaires to fork out the dought to stand on Amazonis Planitia and goggle at this sight you put so much stock in, then let's do it.
What a narrow-minded point of view. So I'm guessing that Hubble, in your mind, was a waste of money too? After all, all it produced to the public mind was a bunch of pretty pictures. Scientists know better, and scientists would know better that a Mars trip would generate more science than a few pretty pictures. But the fact is that Hubble likely generated more money and knowledge than it cost. By far.
That's the whole point of science - that you DO get a return on it, but that it's in ways you can't predict, and so therefore would likely (in a logical manner) never fund in the first place. Humans are short-sighted - nationally funded science programs are a method for counteracting that. Doesn't work THAT well (you generally have to come up with a bunch of bull which makes it sound like work you're doing is practically applicable) but it's better than nothing.
Analogy:
Rewind 2000 years.
"I don't see the reason for building roads all across the Empire. All our population is in one place! When it becomes important, then we can build the roads out in the outer regions. We've got plenty of time. I just don't want them spending MY tax dollars on this stuff now!"
Thankfully, no one said this - or if they did, the rulers realized it for what it was - short-sighted thinking. Ah, the benefits of dictatorships. Space travel is long-term planning. It will pay for itself - many, many times over. You just have to be patient.
Going to mars will not reveal exciting new facts about space to the general public.
Yes it will. It will show what Martian sunset and sunrise look like. From human eyes.
If Hubble proved anything, it proved the US public loves pretty pictures. Hubble rather quickly entered public consciousness as something that we were proud of (thus the MST3K the Movie joke "You killed the Hubble!") and major manned space travel would do the same.
I think you're being a little too cynical about the American public. If it were an international collaborative effort, I'd say you were being too cynical about the collective public, as well. It's true the support may not be there initially - but I think NASA'd find that support for manned space travel to another space body (like Mars) would have tremendous public support, once it started. Considering reaching Mars is a real long term effort, I think NASA'd only find that the public support would grow tremendously over time. I mean, c'mon, stuck on a ship with 3-4 other people for months on end? It's Fox's new reality show!
And for one, it's news about something that the US is doing that will go down in history that does NOT involve mindlessly blowing things up. People like feeling good about themselves (regardless of what current television portrays).
You're definitely correct though that there is no political reason to do it, and that is why it probably will not happen. I'm amazed that no one's written a "Congress simulator" yet - they're so predictable it's frightening. The only thing that moves them to action is fear of not being reelected.
The benefits from the memory subsystem will be offset by the fact that objects containing pointers will be twice as big as on IA32. That means objects could have twice the cache footprint and twice the memory bandwith requirements.
Except that pointers make up only a small fraction of the code footprint of an executable - most of it is ints, which still are 32-bit by default on x86-64. In general you can easily minimize the number of pointers in code by doing math (i.e., with 32-bit ints) on one base pointer.
The estimate is that code size will increase by about 10-15% on x86-64. Considering that the L2 cache is 1MB, as opposed to the standard size of 512k nowadays, it's a net win. Presumedly in the future they'll increase the cache size even more.
Supersymmetry and the Higgs boson are attempts to clean up mathematical holes, but they seem almost well motivated compared to the morass that is string theory.
:)
Supersymmetry isn't an attempt to clean up a mathematical hole: it's an attempt to unify the strong nuclear, weak nuclear, and electromagnetic forces under one umbrella. Any group which covers all of those must necessarily have a supersymmetry. The Standard Model works just fine without supersymmetry - it's just that supersymmetry seems more elegant to people, so they work out its consequences. There's no reason whatsoever that a unified theory MUST exist. It's just that we'd really like it to.
In addition, the Higgs also isn't an attempt to clean up a mathematical hole. It's very, very necessary, and anyone who learns otherwise might want to read more about particle physics. We know that there exists a broken chiral symmetry (the SU(2) group in the Standard Model), and there has got to be a mechanism for providing that. The current 'best method' is the Higgs, and any other method will likely have to 'look like' the Higgs in a lot of ways. There wasn't any 'mathematical hole' unless you call 'lack of theory' a mathematical hole.
Now that's silly. String theory has a lot more direct connections to physics than number theory. I agree with your basic point that string theory is overhyped and tenuously connected with reality, but this kind of hyperbole does not help your case.
He's close. If he would've said "group theory" rather than "number theory", he would've been correct. Group theory is the backbone of a huge amount of modern physics, and there are still subtle points which need to be investigated, though I would never want to do them - hence the reason I am quite happy to let group theorists work it out.
Argh, Slashdot just lost my reply. Grr.
Anyway, the whole situation isn't THAT different than the whole explanation for quark confinement (compressed flux tubes, and all that), the explanation for particle production by an inflating universe (relaxation of lowest-energy modes), or even Feynman diagrams as "particle graphs" - none of them are entirely correct, but they're all 'suggestive', and are easy to understand intuitively. I will agree that the Hawking radiation example is a little too specific for me. I think I'd rather say something like
"caused by the disparity in particle/antiparticle generation near the event horizon, due to the formation of distinct regions in a previously smooth particle/antiparticle sea" - worded more eloquently, of course, but I think that's the issue.
The problem is that the Hawking radiation description actually does contain some real physics there. They're talking about a particle and an antiparticle being generated (some combination of a adagger and adagger a), and one of them being caught in the region of curved spacetime (a adagger/adagger a are different in two different reference frames), resulting in particle generation (because N = adagger a - a adagger is now different).
One caveat, as well: ghost particles aren't virtual particles. They're ghost particles. A virtual particle is a normal particle which is off-mass-shell - it still has all of its correct quantum numbers, just bad energy. Ghost particles don't have correct spin/statistics relation, and therefore aren't particles at all. If memory serves, ghost particles are never external legs in a complete Feynman diagram, which means they're always virtual ghost particles, but they're not virtual particles. Just a bit of a nitpick. (And I didn't think that there -was- a way to solve NAGTs perturbatively without the use of Fadeev-Popov ghosts).
It comes from the fact that in curved spacetime there is no natural choice of time coordinate and so you can't distinguish between positive and negative energy modes meaning that you can't distinguish properly between creation and annihilation operators.
The answer to that's not so clear: it's true the number operator in different (curved) reference frames is different, since the annihilation/creation operators are different. However, saying that has nothing to do with pair-production isn't exactly correct - after all, the zero-point energy, in some cases, generates from normal-ordering (a adagger + adagger a) (in others from symmetry breaking, but I think the same argument applies). You could in fact, define ZPE = integral (adagger a - a adagger), which gives you something like ZPE = integral (N - Ndagger). ZPE density would just be N - Ndagger, and could be interpreted as the number of virtual particle pairs created per unit space per unit time.
Bleh, that's hard to understand without writing things down. Anyway, the point is that if you consider "ZPE" to be "all of the virtual particle pairs in the quantum vacuum", then, for instance, Unruh radiation (and likely Hawking radiation as well) can be explained 'somehow' via virtual particle pairs, as Unruh radiation is just going to be the difference between N in one reference frame and N in another reference frame, hence ZPE in one reference frame, and ZPE in another reference frame. I mention Unruh radiation because it'd be harder to explain 'canonically' than Hawking radiation, though I can somewhat see a way to explain it.
What the actual 'canonical explanation' is, that's a different story. It doesn't tremendously matter, as virtual particle pairs don't appear as two little balls zipping through space at all. It's just a picture for the minds' eye. However, basically saying that the curved spacetime produces a change in particle pair production/destruction rate from one reference frame to another, resulting in a generation of particles, that's perfectly valid, and so, the pair-production argument isn't totally bunk.
Well, there are several reasons Progress slammed into Mir. The source that I had heard (granted, on the Discovery channel) said that one of the cosmonauts saw the problem, and relayed an incorrect direction because he didn't orient himself correctly.
Granted, still not a computer's fault. But proof that navigating in 3D is difficult.
OK, even assuming Chris Sontag (who's rapidly replacing McBride as "Biggest Idiot I've Ever Seen In Charge Of Something He Has No Idea About") honestly intended the BPF code to be an 'example', he missed the point.
It's not obfuscated code. Not at all. It's a clean room implementation, and if he doubts it, he can go to the door of the person who wrote it, and kiss his ass.
Second, they argue that the malloc() implementation is still valid, even after Linus says "well, it was removed" - ignoring the screams by the damned authors of the code saying "Screw off, SCO, it's OUR code, we wrote it, go the hell away."
For everyone out there that thinks there might be something to their claims, there isn't. They're idiots. There's absolutely nothing intelligent that they've pointed out at all, and they've simply proved that they're really attempting a shell game. No, no, look in the other hand. That's where we've got the infringing code!
Easy:
int main()
{
int i = 1;
int j = 1;
exit(i+j);
}
(Note to all nitpickers: yah, yah, all the overhead associated with running a binary MAY make it quicker to run on a massively parallel machine. Blah. You get the point.)
You can't parallelize 1 operation. On a P4 that 1 operation would get done in what, 1 clock cycle? Same for the ES, and the clock speed's higher on the P4, so the wall time is shorter for the P4 by a fraction of a nanosecond. Parallelizable code is actually quite specific, and there are a lot of cases of non-parallelizable code.
You know, I replied to my above message but didn't post it, because I figured "nah, everyone will know what I mean".
I forget what the grammatical mistake is called, but anyway - the "We've simply never done it" referred to 20 or 30, not 2. Yes, we've done 2. 2 is hard. Not easy. Hard. That's why the Progress slammed into Mir once.
20 or 30? That's much harder.
Sounds fine, but is formation flying really going to be the big challenge 20 years from now when we put a very-long-baseline replacement for Hubble up?
The replacement for Hubble is the James Webb Space Telescope (also referred to as the NGST, for Next Generation Space Telescope). This is likely to be its replacement, the Terrestrial Planet Finder.
Anyway, regarding formation flying: Have you ever done it? Fact is, it's hard to get -two- spacecraft to move into relative position to each other, much less 20 or 30. We've simply never done it, and the TPF is NOT the only place we'd want to do it. A gravitational wave telescope, for instance, would be wonderful in space (LISA, I believe, is/was its name) but the concerns were always "can we get satellites to stay within a small fraction of a wavelength of each other?"
This project is designed to say "Yes, yes we can."
Wrong. Getting to the moon is about as expensive as getting to Mars, more or less, largely because Mars has an atmosphere that you can use to brake against for free. Only a fool would go to the Moon, stop there, then launch off again to go to Mars[.]
:) ). With enough lunar infrastructure, a construction yard would make it EXTREMELY easy to build things on the Moon. You then have the additional benefit of not needing to put them through the utter hell of launching off of Earth. Most spacecraft failures and problems come from launch stress problems, and launch from the Moon could be (basically) as gentle as you want.
Hm. True, but then you say...
The Moon is largely made up out of minerals we are quite familiar with here on ol' Terra[.]
Even more true! But then you miss the obvious - it shouldn't be that hard to flat out build spacecraft on the Moon (after all, they've got iron, silicon, etc.), and it's virtually free to launch craft into LEO/GEO/etc. from the Moon's surface (it's about 2 km/s delta-V or so needed, AND there's no atmosphere, so even something like an ion drive will kinda work - you'd still need a bit of an initial boost so you don't run into hills, etc., or a magnetic rail launcher).
If it wasn't for R&D costs and the pathetic state of automated factory technology (and/or the lack of a human base on the moon), fundamentally, you're better off building one factory 'craft, sending it to the Moon, and having it build 20 GEO satellites and launching them into GEO from there, rather than launching 20 GEO craft from Earth.
Note that I'm not talking about the current state of affairs - no way. But fundamentally, the Moon is a nice 'spacecraft launch base', but only if the spacecraft are built there.
Plus you have the added benefit of you don't have to pay for any of the materials. Though strip-mining the moon might piss some people off. Not me, though!
Even if the Moon would end up lacking certain critical materials (it is apparently short on carbon, though it's difficult to say what the subsurface holds), it's probably still a winning situation to ship up small amounts of the missing 'critical materials' (to make steel, for instance) as the materials available on the Moon likely would make up the bulk of the weight of the craft. You also have the added benefit that assembly in 1/6 gee is probably significantly easier for certain tasks than zero gee (and harder for others, but at least if you can't permanently lose bolts by bumping them
In any case, don't discount out the Moon as a launch base - you're definitely right that it's stupid to use it as a stopping point. It's NOT silly to use it as a future launching base and construction/assembly yard.
Starting haphazardly.
:) After it lifts off, depending on the direction, it is doing two things - first, it is escaping from Earth's gravity, and second, it is changing its orbit. You don't have to "add" the escape velocities onto the necessary orbital delta-V. If you wanted it to actually reach a circular orbit, that takes a lot more work, actually!
The delta-v quoted by your source is far lower than the delta-v needed to get into a Hohmann transfer orbit even from free space in a circular solar orbit at Earth's radius (which the C3=0 orbit is the equivalent of). As the Hohmann orbits are the lowest energy transfer orbits that don't require slingshots from other bodies, I question the values on that figure.
Ah, there's your problem. The C3=0 orbit is NOT a circular orbit at Earth's radius. It's a parabolic orbit with Earth at its focus, which necessarily can NOT be a circular orbit about the Sun at Earth's radius. A parabolic orbit means that at infinity, it will have no velocity relative to the Earth, which means, if the craft traveled to infinity, it would then have the equivalent orbital velocity of Earth. Problem is, it never reaches infinity, as it's not a two-body system, since the Sun's there.
If you want a spacecraft to be in a circular orbit at Earth's radius, well, it doesn't have to do anything - just stay home. It already is in one.
This is the problem when you're doing "you need to add an extra 5.03 + 2.38 km/s" - you're adding the Lunar escape velocity and the Martian escape velocity, which you do not need to do, because you're not exactly going to infinity. On the return, you can easily aerobrake in Earth's atmosphere as well to enter lunar orbit.
Also don't forget about aerobraking! No matter what, any time you approach a planet (even entering lunar orbit! you can always place your perigee inside Earth's atmosphere with clever timing!) if you need to slow down, it's free.
And if you don't like that site, how about here, which shows that Deimos is more accessible than the Moon (and shows a delta-V from Mars surface to Lunar surface of 8.0 km/s, not 13.0 km/s).
Or here, where you'll note that "LEO to Mars" is a delta-V of 4.8 km/s, not the 5.6 km/s you're claiming - this is because, of course, it's in LEO, and therefore has some orbital velocity about Earth (and is therefore traveling at -greater- than Earth's orbital velocity at certain points).
I can continue to give examples if you want - the point is that from the Moon, it's easier to get to Mars and back than it is to get to Earth and back.
The easiest way to think about this is simple: You do not need to actually escape Earth orbit in order to reach Mars. A highly eccentric orbit can include both Earth and Mars (if both were stationary, obviously - they're not, so you can't orbit them, but you can of course use that path to transfer between them), and so must necessarily take less energy than the escape velocity of Earth+the escape velocity of Mars (which reaches Mars by going through infinity).
Interestingly enough, Hohmann transfers are not lowest energy. Google for "interplanetary superhighway", which is a relatively recent discovery. Really does suck that the 3-body system isn't analytically solvable...
In order to get to the moon in the first place, you need to have almost completely escaped the Earth's gravity, so it doesn't help for launch of things that are originally from Earth. Best approach for that is to launch them to as _low_ an orbit as you can (so as to minimize delta-v required of high thrust, low-Isp drives), and to spiral the rest of the way out over a period of months using a low thrust, high-Isp drive.
Correct. But it does help for things that are going to Earth. That is, a base on the Moon would be ideal as a place for docking spacecraft that shuttle back and forth between places (like mining the asteroids, for instance). The advantage is that you don't want to bother lifting the 'craft up Earth's gravity well when you don't need to, and of course, if you're transferring things TO Earth FROM the Moon, that's virtually free.
This only applies if the craft MUST dock, because even the Moon has a gravity well. If it can just jettison things, then hell, very clever orbital mechanics wins over the Moon any day.
But, it COULD be useful. It would also be more useful as a manufacturing plant for Earth satellites - launch cost of 2.3 km/s to GEO, rather than 13.8 km/s.
This turns out not to be the case, as you need a lot of delta-v to travel from Mars's orbit to Earth's (the sun's gravity well is deep).
Huh? Mars's orbital velocity is ~24 km/s, Earth's is 30 km/s. That's 5 km/s difference, and escape velocity from Earth is 11 km/s, and Mars's escape velocity is 5 km/s. As far as I can tell, if you escape from Mars's orbit, you'll basically fall back to Earth's orbit, free. I'm just doing back-of-the-envelope calculations, but it seems smaller to me (yah yah, I'm ignoring tons of orbital dynamics, but the points are ~roughly valid). I think the parent poster is correct.
Actually, a brief search online finds that I'm right, as shown here. The DV from Mars C3=0 orbit to Earth C3=0 orbit is 0.9 km/s - virtually nothing! delta-V from Earth's surface to lunar surface is 9.7+2.5+0.7+0.7+1.6 = 15.2 km/s. Delta-V from Mars surface to Lunar surface is 4.1+0.9+0.3+0.2+0.9+0.7+1.6=8.7, which is almost a factor of 2. I think more clever methods could probably be derived to lower that to less (using Phobos or Deimos for a gravity handle, if they're rotating in the proper way... I can't think off hand).
The Sun's gravity well is deep, but 1/r^2 wins every time.
They do, it's whatever kernel Red Hat are shipping, you can get the source. ISVs need some common point, or you are going to have Oracle requiring kernel A and SAP/Veritas/etc. requiring kernel B which aren't mergable.
/etc/sysconfig/ or require Java. I suppose they could just ship their own distro. ... yeh just what I want: 15 different distros. to manage, I'm running Oracle/Veritas/WebSphere on this box and SAP/Streams/PowerPath on that one over there.
/etc/init.d, a configuration in /etc/foo.
Bullshit. Red Hat's kernel isn't static - it moves just like any other. So if one says "You must use Red Hat 7.3" and another says "You must use Red Hat 8.0", you could be screwed in any case.
Ah, now you're going to say "well, they'll just say 'the most current Red Hat' and keep it current!" except that this is identical to saying "the most recent Linux kernel" and keeping it current, except that checking against the most recent Linux kernel would be less work than installing a new version of Red Hat.
Well unless they call "chkconfig", or "service" or, configure some file in
That's right. Because the source code to chkconfig or service isn't available at all. Oh yeah, that GPL thing. Besides, what the hell are they doing messing with files in the system configuration? And no, that isn't an idle comment - there is no reason to be puddling around in some vendor-specific files. Install a script in
Java? Last time I checked Java wasn't Red Hat specific, and it is relatively trivial to figure out what Java runtime is on a system. Give me a break. This is what "configure" scripts are for. If a company says "Red Hat Only!" then they don't understand computers and/or the operating system they're writing for. And that's ALWAYS dangerous.
Oh sure, you can just "apt-get update" to mirror the latest stable (or however), but it you're looking for specific sets of code, in specific versions, then just rattling off a quick command to "just work" and get all the most current stuff isn't exactly an option, no? You still have to put together at least a package list to grab. Can do the same thing with RPMs.
Huh? You don't need to put together a package list to grab - not if you're using the latest releases from Debian. Then they already exist for you.
apt-get update
apt-get upgrade
done.
There are two points with this:
With Red Hat, you can't - a Red Hat 6.2 distribution has to be 'upgraded' to a 7.0 distribution. This is what makes it easy to upgrade. I never have to worry about Hey, should I upgrade to Debian 3.0? Hell, I didn't even KNOW when Debian 3.0 came out - I just noticed "wow, my login changed. That's neat!"
I've done it quite a few times rebuilding a specific machine state when I've been tinkering and not quite understanding what I'm doing with the code I'm massaging.
The point is I don't want to do ANYTHING. It's easy enough - tell the user to install all custom apps under ~ and ~/lib/, etc., and then I don't even need to bother about doing backups of the main system, nor even a package list, because it'll take no time to actually have it rebuild everything.
So I'm guessing you've got a Red Hat house, right? How many times have you reinstalled Red Hat - even to 'upgrade'? Once? That's too much. There is ONE reason to reboot a machine - to change the kernel. Other than that, there is absolutely no good reason to reboot at all. Worst comes to worst, switch to single-user, then kick back up to multi-user.
It was when it was suggested that we need to upgrade all 5 of our then-Red Hat boxes to RH7.x that I said "this is incredibly dumb. There's got to be a better option". There was.
Look, it's not deb vs. RPM (don't say apt vs. RPM - APT is not a package format). It's 'standards' vs. 'thrown together haphazardly'.
Yes. You're right. You can do that.
The problem is that for Red Hat, there are more 'badly behaved' RPMs than there are 'badly behaved' packages in Debian - especially Debian stable.
The other thing is that for Debian, I do not need to set up a local source or package repository. I use one of the Debian mirrors, and poof, everything's good. If you use stable (which is NOT that out of date, regardless of what people say) then when a package updates, big deal - it'll STILL just work.
Those 7-10 identical PCs just run Debian. Nothing special. Nothing amazing. Just Debian.
Yah, it took about 15 minutes of poking around apt-get's man page to find how to upgrade only the security packages by default (you CAN do this - apt-get update; apt-get upgrade;apt-get update with the options to select a different APT config for the first two, and create one that only has the security servers) - but it wasn't that hard, and now we've got automated security updating. Works for me!
I can not STAND people that say "Oh, well, it won't run on anything but Red Hat". Give me a break. The operating system is called Linux, not Red Hat (OK, maybe GNU/Linux). Linux defines the API and the application interfaces (ditto GNUification), and quite simply, everything that runs on Red Hat will run on Debian.
Period. Wackos who tell you "oh, maybe it's a problem with Debian" simply don't understand the way computers work. That's why I can't stand that Oracle won't support anything except Red Hat. That's silly. More than silly. They wrote a program, that works under Linux, not under Red Hat. If it's kernel version dependent, state the kernel versions it was tested under - or better yet, give the source tree! (wow!) If it's library dependent, give the library versions. If it's library dependent, static link the damned thing. There is nothing that runs under Red Hat that can't run under Debian.
You know what someone really needs to do? Write a bunch of scripts that let one distribution 'play' as another one, so you can just reboot and launch as a Red Hat clone, Debian clone, etc. (if you don't need a new kernel version, you don't need to reboot). It can't be that hard. That way when someone asks you what type of Linux you're using, you can say "What type would you like it to be, so I can then prove to you that you're being an arrogant prick and it really IS your problem?"
"distro-mode redhat". That'd be cool.
One of the nice things regarding Debian is that basically all it is is a set of installed packages - no extra magic, basically. Creating a local mirror is as easy as creating a local APT source and storing all the packages there, and then instead of running apt-get update on the machines, run apt-get update on the mirror PC, which updates all of them. If the mirror PC works fine, then copy all the packages to the local APT source, and boom, you're fine. The details here are sketchy, yah, but it's an easy problem.
Regarding the security patches, I honestly don't know what problem you have with them: maybe Debian has really improved security support since then, but if you check Debian's page, you'll see that security.debian.org's response time is just as fast as any of the other major distros. There are several bugs for which Debian had a package that fixed the problem first (the SSH bug that required privsep comes to mind).
And honestly, I have NO idea what problem you had where a package broke something badly, unless you were running unstable. In my experience, Debian's packages are FAR less likely to break a system than some random less-0.4.3-mdk3-only-work-on-a-sunday.rpm. The few problems I've had were dumb problems that were immediately obvious (and in fact were stupid user errors, as I forced an upgrade of a package without forcing the upgrade of its neighbors).
I've never been happier since I converted my lab's PCs to all Debian. Yah, it's small, but I have to handle something like 7-10 PCs, and having them all in almost exactly the same state (which is far harder to do in Red Hat than in Debian) is SO nice.
I mean, the main reason Debian stable is farther behind than everyone else is because they take their time. When they mean stable, they really really mean stable - not just stable as in 'won't crash', but stable as in 'will do what it says it does'.
Plus, like the complete bastards that they are, male mosquitos are pollinators! Only the females are the bloodsucking disease spreading type.
Honestly, wiping out mosquitos probably wouldn't hurt birds, bats, spiders, frogs, etc. But the lack of pollinators would really screw certain plants up, which could do bad things.
Plus the ever-important thing to remember is that mosquitos are only a vector. They're not truly the problem - if you remove mosquitos by killing them all, something new will fill that niche, and probably rather quickly, and poof, malaria all over again. Life likes to evolve to new niches.
The better thing is of course to cure the disease, because, as you said, there is little to no beneficial role in human diseases anymore.
Careful - you didn't say "direct" effect, because ecology
"is rarely direct." Damnit. Didn't mean to hit the submit button there. Oh well, hopefully it doesn't look TOO bad.