Re:Good idea for nuclear waste?
on
Going Up?
·
· Score: 2
It's not energy - it's angular momentum.
You need some way of generating thrust to counteract that momentum so you can fall easily. If you want something that doesn't require propellant, you're talking about a solar sail, and that requires a lot of course corrections to sail into the Sun. It also would probably take quite a bit of time, and require a fair amount of extra material. That is, money.
First, the principle is not the same. Keeping something in orbit with Earth is difficult only because the atmosphere tries to bring it down for LEO stuff, and for avoiding other craft. It is also ridiculously quicker to deorbit something that is a few km above your target as opposed to 1 AU above your target, and manpower and money are proportional to time - it would take ridiculously longer to deorbit something from the Sun - years, decades - and you'd have to have someone monitoring it the entire time. That's expensive - especially the monitoring part. The DSN is quite crowded.
Re: Mercury - It will take 5 years, and 3 gravity assists just to get to Mercury orbit. Mercury still has 60% of the orbital velocity that the Earth has, and still is very far from the Sun: 0.4 AU! It would take several more gravity assists and a VERY complicated orbit to get to the Sun. Remember: gravity assists aren't free. You still need to GET to the planet, and that takes fuel.
Re: Venus - see the Mercury argument.
Re: SOHO - SOHO is in the Earth-Sun L1 point. It's not very much closer to the Sun than the Earth is.
You're not understanding things if you think that you can just slingshot off of Venus or Mercury. Slingshotting doesn't work the way you think it does, and you can't always do it - you can only do it if your orbit is favorable with respect to their position, so you may only get a shot to do it once or twice a year. In addition, all you'll really do is remove from your orbital velocity whatever the respective velocity is wrt the planet you're slingshotting from. It would take probably around 8 or 9 gravity assists to get an orbit that would collide with the Sun, and a lot of burns and a lot of manpower to get those gravity assists correct.
Almost every sub-Mercury orbit you could do cheaply would be hyperbolic and throw the thing out of the solar system - if you're lucky. You're not understanding the costs of space flight if you don't understand that. Throwing something into the Sun is expensive. People lots smarter than you and me have looked into this, and the answer is always "it's too much."
Re:Good idea for nuclear waste?
on
Going Up?
·
· Score: 2
Nah - actually I thought about this for a while, and I realized where my mistake was. It's not tacking, but it will work.
You can change the direction of the force by changing the direction that the light reflects. That is, tilting the mirror. If you do that, then the net force is at an angle, and you can cancel orbital velocity. It will increase your radial velocity a little, so it'll ellipticize your orbit. You then fold the sail, and let the decreased tangential velocity bring you closer to the sun, and then do it again at the opposite end of the orbit as when you did it before. This circularizes your orbit slightly, and pulls the other end closer - step and repeat. It's slow, and more importantly, it needs to be monitored and controlled, which means it's expensive. But it would work.
It's not tacking, though - not even similar.
Re:Good idea for nuclear waste?
on
Going Up?
·
· Score: 2
Actually, as I pointed out somewhere else, your calculation is off by about 40%, since you're shooting the object 23.5 degrees out of the ecliptic. Plus that also is a problem since even if you cancel off all of the 30 km/s, you'll have the residual 12 km/s out of the plane of the ecliptic, which will just produce a very elliptic orbit. Propellant, propellant, propellant. You'd probably want to cancel off all but 6 km/s ecliptic + 4 km/s out of ecliptic (~ 7 km/s tangential). 7 km/s is still a lot to get rid of. It isn't free - no way.
If you only saw launch problems, you didn't look enough. Most of them deal with this question and the basic answer isn't launch energy, it's removing the orbital energy that matters.
Launch only matters from Earth's perspective. From the Sun's perspective, you're still going 30 km/s. Even after the space elevator, you're still going 26 km/s. You've got to kill that energy somehow.
If you're going to be disposing of things, you want it to be cheap, right? If it's really expensive, then it's not going to be worth it - it's not THAT dangerous, and shoving it in some corner of Earth is better. We're talking about cost here: I never claimed it wasn't possible, I just claimed it wasn't feasible.
I don't think you quite understand what the problem is. Once you get out of the Earth's orbit, you've then got to get on an impact path with the Sun. This isn't easy! This is very very difficult, and it requires removing a lot of angular momentum. Slingshotting around the moon won't do it. That'll slow you down a BIT, but not much: you can figure out how much it will slow you down pretty easily.
30 KM/S. That's a lot of speed. After the elevator, you're 23.5 degrees out of the ecliptic, traveling at 26 km/s in the ecliptic, and 3 km/s out of the ecliptic. Your relative speed to the moon won't be huge - maybe 4 km/s - and so you'd need 5 SLINGSHOTS around the moon to kill off most of your orbital velocity. Plus you'd need people controlling those slingshots to make sure the orbit is right, which is a lot of money. Never mind the fact that you need to ditch that 3 km/s before you're too far out of the ecliptic for anything to help you at all.
Basically, the Sun's gravity is not helping, at all. The object's in orbit. Gravity's going to keep it in orbit, and not pull it closer to the Sun. You've got to do that, by eliminating its tangential velocity. And that's a hell of a lot of energy.
Bottom line: if it isn't cheap, it's not feasible, and it won't happen. And until you find a way to strip 30 km/s away from an object, it's not cheap. Slingshots, solar sails, and propellant are all expensive (either in materials or in manpower) and the elevator doesn't really help that much. Launch costs are only a portion of the equation here.
Re:Good idea for nuclear waste?
on
Going Up?
·
· Score: 2
Velocity is velocity is energy. If you're going 26 km/s, then you're going 26 km/s, and you're going to need to burn a hell of a lot to get rid of all of the energy. If you use a slower propulsion system, then you need to use it a much longer time, and you need much more propellant.
(OK, someone suggested solar sails, and it must be possible, but I still don't understand it. Still, there you're talking years/decades, and a LOT of extra mass tacked on)
It just isn't feasible, and it sure as hell isn't free.
Re:Good idea for nuclear waste?
on
Going Up?
·
· Score: 2
Woo. That'd be one HELL of an oscillation to avoid Venus and Mercury. Damn them for being in the ecliptic!
Re:Good idea for nuclear waste?
on
Going Up?
·
· Score: 2
Correction: you don't mean solar wind. You mean light pressure. Solar wind is made of charged particles, which wouldn't work that well for the solar sail issue. Light pressure is better. But anyway...
Light goes out radially: how would you slow it down using this? It's constantly pushing it outwards.
I've always been confused about this: how exactly would you move radially inward against something that's moving radially outward? This isn't like sailing where you have something else to push against. I can't see anyway to get a net velocity inward.
Space elevators by definition are counterbalanced: what I was saying was that there wasn't a convenient break point, as in an asteroid-balanced one. It wouldn't be an issue - you'd need to break the cable, and that's a fundamental problem.
If you can break the cable, then yes, all hell breaks loose.
Re:Good idea for nuclear waste?
on
Going Up?
·
· Score: 2
The counterweight's not being planned, for difficulty: they're doing it with a pure strand.
The difference in tangential orbital vel. is minimal here: you're talking about the difference between the Earth's position wrt Sun, and the top of the Elevator's position wrt Sun. They're identical, as far as anyone cares: it's six orders of magnitude difference.
But, anyway: figure it out. OK. Cable's 100,000 km long, right? That'll give you 7.3 km/sec let go at the highest point. You're right: that is a good fraction of the 30 km/sec needed to impact the Sun, but it's not all of it. And that remaining amount is just plain friggin' huge. You can figure out the amount that needs to be removed to hit the Sun (rather than direct impact) but it's still not going to be efficient.
There's another problem here, though: the elevator is located at the equator, and it is not rotating in the same plane as the Earth is wrt the Sun. It's rotating 23.5 degrees wrt the ecliptic. So you'll build up 7 km/sec, but of course, a large fraction of that is out of the ecliptic, which doesn't help you at all: in fact, 40%! So really, the elevator only helps you out with ~ 4 km/sec against the 30 km/sec you're traveling. Plus now you're moving out of the ecliptic, so that additional 3 km/sec actually adds to the amount you need to get rid of, if only slightly.
Bottom line: 26 km/sec vs. 30 km/sec: it still sucks.
Re:Good idea for nuclear waste?
on
Going Up?
·
· Score: 2
You're looking at it from the wrong point of view: from Earth's point of view. Look at it from the Sun's point of view. Even if you head backwards (against the Earth's rotation), you've still got a LOT of angular momentum to kill: orders of magnitude larger than any velocity you'll accumulate leaving the cable.
Figure it out: what's the circumference of the Earth's orbit? Divide it by one year in seconds, and poof, you've got your orbiting speed: 30 km/sec. They're talking about 120 - 160 km/h (hour!) or 0.04 km/sec. Then you've still got to eliminate 30 km/s. At that point you might as well have launched from Earth's surface: the additional benefit of the elevator is meaningless.
Re:Good idea for nuclear waste?
on
Going Up?
·
· Score: 5, Insightful
It's not feasible to send waste into the sun - take a look through a few astronomy texts and you'll see why.
Basically the problem is that any object we lift from the Earth has energy, and angular momentum. If you want to hit the sun, and not just put it in a very eccentric orbit, you need to remove a lot of energy from the object, and the space elevator wouldn't help - it pulls you out of Earth's gravity well, not out of Earth's orbit. You'd require massive amounts of fuel to get it there.
Re:Environmental impact
on
Going Up?
·
· Score: 4, Insightful
The Elevator in Red Mars fell down because it had an asteroid at the far end providing counterbalance. Separate the asteroid from the cable, and it's no longer a space elevator, but a really stupidly placed cable. Flop. Splat.
The elevator they're proposing is not counterbalanced - this requires it to be even longer than if it wasn't counterbalanced, but it doesn't require a conveniently placed asteroid.:)
Remember: you're asking what if it falls, right? It is falling. It just happens to be falling at exactly the same rate that the Earth is turning. It's in orbit. In order to make it fall, you'd need to break it.
(1): C14's decay product can't be C12, you'd lose atomic number there. C12 has 12 nucleons, C14 has 14 nucleons. C14's decay path is N14 (neutron -> proton + electron + antineutrino: Slashdot needs "physicscode").
(2): By ambient level, I meen "initial ratio" of C12 to C14. You need to know this. Without it, you have no idea about anything. So C14 dating assumes that the C14 level in the atmosphere was constant over time, and the crosscalibration indicates that assumption is mostly correct.
If you put an unlimited number of all the pieces of an airplane in an unlimited number of big piles, and let an unlimited number of airplanes sweep through them, and then sweep away the piles that don't look like you want them to look like - repeat ad nauseum, and in the limit of infinite repetitions, you'll get an identical airplane, and then no, you won't be able to tell them apart. The problem is that you're looking at an end product and saying "That must be designed." I could look at a pile of dirt, study it for years, and say "that must be designed" and still be wrong. See also Cydonia on Mars.
Human timescales differ from universal timescales. Evolution is a very messy process, and produces a lot of crap. People born with gills, for instance. But, hey, I'm not exactly one to criticize: I haven't built any universes lately.
Reread my post: in the limit of the two theories that I stated, one is the direct opposite of the other.
Aliens genetically constructed the earth as their terrarium: that falls under "creationism" - instantaneous creation of Earth at some point in time in the past (or relatively instantaneous...).
Universe laid by a giant bird: Falls out of the scope of the theories, as the theories describe Earth's creation. Rewriting "Earth laid by a giant bird." Falls under "creationism" - instantaneous creation of Earth.
If you define evolution and creationism as I did, they're opposites of each other. If Earth wasn't created instantaneously at some point, it must've been created over some period in time. Likewise, if the Earth wasn't created over a period in time, it must've been created instantaneously. I didn't give you a "how". I gave you a "when".
Re:Refuting Evolution
on
Genome
·
· Score: 3, Informative
There's a hell of a lot of data on calibration of C-14 dating. For some they used historical references, others they used tree-ring calibration. It's not far off, in most cases. If the parent to your post was trying to say that C-14 data gives dates >1 million years off, he/she's on crack: C-14 is only accurate up to 60K years or so. It's also almost definitely order-of-magnitude correct. The problem mostly stems from two sources:
1: Varying C-14 levels in the atmosphere over time (sunspots) 2: Point at which carbon-exchange ended in the object.
The first one is not that severe, honestly, and the second only applies to nonliving things. For living things we can pretty accurately assume that carbon exchange ended when it died.:) The first one however can produce dates which drift significantly as you go farther and farther back in time, as the "C-14 timeline" will "compress" and "expand" - that is, certain stretches of "real time" will correspond to unequal portions of "C-14 time" based on the levels of C-14 in the atmosphere at those points.
Radiometric dating is very accurate if you know the ambient level throughout the period that isotope exchange was occuring, and then when the isotope exchange stopped. If you're off significantly on either one of those, you could have problems. But that's what cross-calibration is for.
Depends on your definition of "evolution" and "creationism". If you define "evolution" as the change over time of the Earth into what it is today, and "creationism" as the instantaneous creation of the Earth at some time in history, then yes, they are the direct opposites of each other, and to negate one proves the other.
You're talking about specifics of evolution (which is scientific theory) rather than the evolution mindset (which is a mindset). Debate the specifics of evolution (theory) and you'll get dogmatic response, unless you go after something which is still an open question, from the community's point of view. You can't really debate a mindset, though.
And astronomy/physics is extremely dogmatic! All science is. Try offering an alternative explanation other than the Big Bang, and we'll look at you like you're crazy (because you probably are - you can SEE the Big Bang if you look at the sky in microwave). You're talking about "offering an alternative explanation for something that was considered over and done with." In any science, you'll get a sharp response in that area. The other end, where you're talking about non-constancy of physical constants, that's ALWAYS been considered an open possibility. You can find papers on that back over a hundred years.
Doubt me on the dogmatic nature of astronomy and physics? Look for papers on alternative answers to the Higgs boson, and see if you find papers which reference them and support them. You won't. Even though the Higgs boson hasn't been found, and there're still possibilities if it can't be found, they aren't being looked at.
... actually, it assumes a flowing system, for carbon dating life with C14. Carbon-14 dating assumes that there's continual carbon exchange, and at some point the carbon exchange stopped. For a living creature, that's when it died, as it stopped breathing.
Problems in C14 dating don't make the method wrong, they make the implementation in certain aspects wrong. That's like declaring that Wien's model of the blackbody curve is wrong in the exponential tail simply because it gets the early part wrong. C14 is very accurate if you know when the carbon exchange stopped, and that'll put the age of certain things very very old.
Most of us do the research. The problem is with people who claim that a method is flawed because they found one example where it (supposedly) doesn't work. Overwhelming evidence that supports it is enough to convince logical people.
People who believe in literal creationism (that is, literal "English" creationism - literally the process that is described in the English translation of the Bible) are taking explanations way out of context.
They should also go to Egypt and look for bread (made of grain) to fall from heaven on their heads (rather than manna, which is real), and far more amusingly, only forgive each other 490 times. After that, screw you, jackass.:)
The problem is that we are far, far removed from the people who read the original version of the Bible. We don't know the colloquialisms. Even scholars don't know. Even the original versions of the Bible (Hebrew) may be very far off from the true original, because we simply do not have the colloquial context. (For example: we use the word "heart" in multiple contexts, and it's difficult to discern which version we mean. There's no reason to believe that they didn't have similar concepts as well.)
I honestly wonder when people start supporting creationism. I really want one of them to explain to me what happened. What do they REALLY think happened? Genesis's account is vague - clear it up. Exactly how did God separate the Earth from the heavens? Basically, if you keep saying "How?" "How?" "How?" to someone espousing creationism, you'll get one of two answers. "He just did" or "I don't know." The response to the first is "that's not an answer", and the response to the second is "That's what I'm trying to figure out."
Here's the thing: if you can't reconcile Genesis with science in your head, you're not thinking enough. It's easy - it really is. All science does is stick a bunch of answers where Genesis is vague.
Religions answers "Who". Science answers "How". Don't people ever take journalism classes?
Re:This is getting ridiculous!
on
What, Me Worry?
·
· Score: 2
Did you read the article? It's less about the fact that the asteroid strike was being blown out of proportion and more about HOW it was blown out of proportion, and the dangers of overblown media hype with this sort of an issue.
Yes, we know it was overblown. Yes, we've known it for a while. But no, I did not know exactly how it happened. Apparently it's one guy who commented to the BBC in a very dangerous manner - something along the lines of "this object is the most dangerous object thus far encountered." The BBC then took this completely out of context and mediafied it.
Look, this is dangerous: it's more dangerous than the asteroid. This is the classic story of the boy who cried wolf, except in this case, it'd be better described as "the detached aloof boy who commented on a wolf-like smell in the air often and the other little boy who cried 'wolf' every time the first boy mentioned it." Media's been jumping on every factual statement that NEO scientists have been making, and people are getting to the point where any asteroid strike is going to be laughed at. This is dangerous. Very very dangerous. It's not like asteroid strikes don't happen. It's not like it wouldn't kill us. It's not like it wouldn't be very, very difficult to stop.
It is not about the apps. It's about the toolchain, and the libraries. You said it yourself:
Linux/BSD -- no problem at all. Just recompile.:-)
But that implies a wealth of things: a working compiler that works as good and is as efficient as the old one, with as few bugs as possible. If you write the compiler from scratch, this is not going to be the case. It is not going to be as good and as efficient as one that's been worked on for an incredibly long time.
There's a wealth of information on this subject out there: take a look at AMD's presentations showing the progression of SPECint95 scores as improvements in CISC (x86) based designs completely eliminated the differences between architectures. You flat out do not get much of a performance boost from switching architectures: a well optimized design reduces any ISA to an optimal architecture.
Think about it this way. When you upgraded processors before in x86-land, the worst that could happen would be a really bizarre bug would show up that could cause strange things to happen, but for the most part, everything worked. See the F00F bug, the Pentium fdiv bug, etc. etc. If you switch processors and move from IA32 -> IA64, the whole damned OS could fall apart and not run straight from the beginning because of a compiler bug. It's an integration nightmare.
Man. Then when you think that IA64 puts a huge strain on compiler writers, it's no wonder that people look at x86-64 and say "that might not be a bad idea."
As for the die space argument you had at the end, cache is huge, decoding/translation is tiny. You're talking orders of magnitude difference here. Think about it in the reverse sense. If you had something that increased die size by, say, even 1%, and allowed backwards compatibility with absolutely tons of applications, wouldn't you do it?
... and praying that the compiler doesn't introduce a thousand new bugs. Gee, that never happened before.
Sticking with x86 means that the old compilers will work as well as they did before, and are far less likely to contain bugs than being compiled by a totally new compiler.
Honestly, I don't see why it's that bad. Slowly but surely, they're eliminating the bad portions of the x86 ISA, and everything still runs. Starting from scratch means that you need to relearn all sorts of optimization techniques.
I think you're missing the point: all you need is a compliant OS. Applications can become "compliant" on a case-by-case basis. A long mode OS can run non-long mode apps simply by clearing the L bit (cf. AMD's x86-64 whitepaper). This is basically identical to the way that the 32-bit stuff ran, except you don't have "standard 16-bit mode" available under a long mode OS. That's fine - the processor can still run the stuff, you just need to reboot. Perfect.
How long do you think it's going to be before Microsoft puts out a 64-bit Windows XP? Not long. Why? It doesn't take any time, and they get to charge people more money. Sounds like a Microsoft solution to me. Once you've got the thing running a 64 bit OS, then it's pick-and-choose 64-bit mode on an app-by-app basis.
Erm, OK, need to correct that a bit, mainly because the P4 is such a weirdo.
The P4's trace cache kindof eliminates the x86 translate penalty, because the trace segments for the long x86 instructions come from the microcode, rather than from a translation engine. In fact, if you think about it, you're really not hurt at ALL by having x86 here, because if someone wants to do one of these weird x86 instructions, well, they'd want to do it in your new ISA as well, and it'd be awkward there. The correct solution here would be "don't have the idiot programmer do that" but that's not the processor designer's fault, it's the compiler's fault for using such a clunky instruction (or the programmer's fault, for using a stupid assembly instruction).
Honestly, let processor designers go wild, and they'll come up with dozens of ways to fix a broken ISA, until it doesn't matter anymore that the ISA has stupid cruft in it, because only the "intelligent parts" remain. I think Hammer's a step in that direction as well, by increasing the number of registers, and by eliminating the x87 cruft in full 64-bit mode.
Slashdot Mirror
It's not energy - it's angular momentum.
You need some way of generating thrust to counteract that momentum so you can fall easily. If you want something that doesn't require propellant, you're talking about a solar sail, and that requires a lot of course corrections to sail into the Sun. It also would probably take quite a bit of time, and require a fair amount of extra material. That is, money.
First, the principle is not the same. Keeping something in orbit with Earth is difficult only because the atmosphere tries to bring it down for LEO stuff, and for avoiding other craft. It is also ridiculously quicker to deorbit something that is a few km above your target as opposed to 1 AU above your target, and manpower and money are proportional to time - it would take ridiculously longer to deorbit something from the Sun - years, decades - and you'd have to have someone monitoring it the entire time. That's expensive - especially the monitoring part. The DSN is quite crowded.
Re: Mercury - It will take 5 years, and 3 gravity assists just to get to Mercury orbit. Mercury still has 60% of the orbital velocity that the Earth has, and still is very far from the Sun: 0.4 AU! It would take several more gravity assists and a VERY complicated orbit to get to the Sun. Remember: gravity assists aren't free. You still need to GET to the planet, and that takes fuel.
Re: Venus - see the Mercury argument.
Re: SOHO - SOHO is in the Earth-Sun L1 point. It's not very much closer to the Sun than the Earth is.
You're not understanding things if you think that you can just slingshot off of Venus or Mercury. Slingshotting doesn't work the way you think it does, and you can't always do it - you can only do it if your orbit is favorable with respect to their position, so you may only get a shot to do it once or twice a year. In addition, all you'll really do is remove from your orbital velocity whatever the respective velocity is wrt the planet you're slingshotting from. It would take probably around 8 or 9 gravity assists to get an orbit that would collide with the Sun, and a lot of burns and a lot of manpower to get those gravity assists correct.
Almost every sub-Mercury orbit you could do cheaply would be hyperbolic and throw the thing out of the solar system - if you're lucky. You're not understanding the costs of space flight if you don't understand that. Throwing something into the Sun is expensive. People lots smarter than you and me have looked into this, and the answer is always "it's too much."
Nah - actually I thought about this for a while, and I realized where my mistake was. It's not tacking, but it will work.
You can change the direction of the force by changing the direction that the light reflects. That is, tilting the mirror. If you do that, then the net force is at an angle, and you can cancel orbital velocity. It will increase your radial velocity a little, so it'll ellipticize your orbit. You then fold the sail, and let the decreased tangential velocity bring you closer to the sun, and then do it again at the opposite end of the orbit as when you did it before. This circularizes your orbit slightly, and pulls the other end closer - step and repeat. It's slow, and more importantly, it needs to be monitored and controlled, which means it's expensive. But it would work.
It's not tacking, though - not even similar.
Actually, as I pointed out somewhere else, your calculation is off by about 40%, since you're shooting the object 23.5 degrees out of the ecliptic. Plus that also is a problem since even if you cancel off all of the 30 km/s, you'll have the residual 12 km/s out of the plane of the ecliptic, which will just produce a very elliptic orbit. Propellant, propellant, propellant. You'd probably want to cancel off all but 6 km/s ecliptic + 4 km/s out of ecliptic (~ 7 km/s tangential). 7 km/s is still a lot to get rid of. It isn't free - no way.
If you only saw launch problems, you didn't look enough. Most of them deal with this question and the basic answer isn't launch energy, it's removing the orbital energy that matters.
Launch only matters from Earth's perspective. From the Sun's perspective, you're still going 30 km/s. Even after the space elevator, you're still going 26 km/s. You've got to kill that energy somehow.
If you're going to be disposing of things, you want it to be cheap, right? If it's really expensive, then it's not going to be worth it - it's not THAT dangerous, and shoving it in some corner of Earth is better. We're talking about cost here: I never claimed it wasn't possible, I just claimed it wasn't feasible.
I don't think you quite understand what the problem is. Once you get out of the Earth's orbit, you've then got to get on an impact path with the Sun. This isn't easy! This is very very difficult, and it requires removing a lot of angular momentum. Slingshotting around the moon won't do it. That'll slow you down a BIT, but not much: you can figure out how much it will slow you down pretty easily.
30 KM/S. That's a lot of speed. After the elevator, you're 23.5 degrees out of the ecliptic, traveling at 26 km/s in the ecliptic, and 3 km/s out of the ecliptic. Your relative speed to the moon won't be huge - maybe 4 km/s - and so you'd need 5 SLINGSHOTS around the moon to kill off most of your orbital velocity. Plus you'd need people controlling those slingshots to make sure the orbit is right, which is a lot of money. Never mind the fact that you need to ditch that 3 km/s before you're too far out of the ecliptic for anything to help you at all.
Basically, the Sun's gravity is not helping, at all. The object's in orbit. Gravity's going to keep it in orbit, and not pull it closer to the Sun. You've got to do that, by eliminating its tangential velocity. And that's a hell of a lot of energy.
Bottom line: if it isn't cheap, it's not feasible, and it won't happen. And until you find a way to strip 30 km/s away from an object, it's not cheap. Slingshots, solar sails, and propellant are all expensive (either in materials or in manpower) and the elevator doesn't really help that much. Launch costs are only a portion of the equation here.
Velocity is velocity is energy. If you're going 26 km/s, then you're going 26 km/s, and you're going to need to burn a hell of a lot to get rid of all of the energy. If you use a slower propulsion system, then you need to use it a much longer time, and you need much more propellant.
(OK, someone suggested solar sails, and it must be possible, but I still don't understand it. Still, there you're talking years/decades, and a LOT of extra mass tacked on)
It just isn't feasible, and it sure as hell isn't free.
Woo. That'd be one HELL of an oscillation to avoid Venus and Mercury. Damn them for being in the ecliptic!
Correction: you don't mean solar wind. You mean light pressure. Solar wind is made of charged particles, which wouldn't work that well for the solar sail issue. Light pressure is better. But anyway...
Light goes out radially: how would you slow it down using this? It's constantly pushing it outwards.
I've always been confused about this: how exactly would you move radially inward against something that's moving radially outward? This isn't like sailing where you have something else to push against. I can't see anyway to get a net velocity inward.
Space elevators by definition are counterbalanced: what I was saying was that there wasn't a convenient break point, as in an asteroid-balanced one. It wouldn't be an issue - you'd need to break the cable, and that's a fundamental problem.
If you can break the cable, then yes, all hell breaks loose.
The counterweight's not being planned, for difficulty: they're doing it with a pure strand.
The difference in tangential orbital vel. is minimal here: you're talking about the difference between the Earth's position wrt Sun, and the top of the Elevator's position wrt Sun. They're identical, as far as anyone cares: it's six orders of magnitude difference.
But, anyway: figure it out. OK. Cable's 100,000 km long, right? That'll give you 7.3 km/sec let go at the highest point. You're right: that is a good fraction of the 30 km/sec needed to impact the Sun, but it's not all of it. And that remaining amount is just plain friggin' huge. You can figure out the amount that needs to be removed to hit the Sun (rather than direct impact) but it's still not going to be efficient.
There's another problem here, though: the elevator is located at the equator, and it is not rotating in the same plane as the Earth is wrt the Sun. It's rotating 23.5 degrees wrt the ecliptic. So you'll build up 7 km/sec, but of course, a large fraction of that is out of the ecliptic, which doesn't help you at all: in fact, 40%! So really, the elevator only helps you out with ~ 4 km/sec against the 30 km/sec you're traveling. Plus now you're moving out of the ecliptic, so that additional 3 km/sec actually adds to the amount you need to get rid of, if only slightly.
Bottom line: 26 km/sec vs. 30 km/sec: it still sucks.
You're looking at it from the wrong point of view: from Earth's point of view. Look at it from the Sun's point of view. Even if you head backwards (against the Earth's rotation), you've still got a LOT of angular momentum to kill: orders of magnitude larger than any velocity you'll accumulate leaving the cable.
Figure it out: what's the circumference of the Earth's orbit? Divide it by one year in seconds, and poof, you've got your orbiting speed: 30 km/sec. They're talking about 120 - 160 km/h (hour!) or 0.04 km/sec. Then you've still got to eliminate 30 km/s. At that point you might as well have launched from Earth's surface: the additional benefit of the elevator is meaningless.
It's not feasible to send waste into the sun - take a look through a few astronomy texts and you'll see why.
Basically the problem is that any object we lift from the Earth has energy, and angular momentum. If you want to hit the sun, and not just put it in a very eccentric orbit, you need to remove a lot of energy from the object, and the space elevator wouldn't help - it pulls you out of Earth's gravity well, not out of Earth's orbit. You'd require massive amounts of fuel to get it there.
The Elevator in Red Mars fell down because it had an asteroid at the far end providing counterbalance. Separate the asteroid from the cable, and it's no longer a space elevator, but a really stupidly placed cable. Flop. Splat.
:)
The elevator they're proposing is not counterbalanced - this requires it to be even longer than if it wasn't counterbalanced, but it doesn't require a conveniently placed asteroid.
Remember: you're asking what if it falls, right? It is falling. It just happens to be falling at exactly the same rate that the Earth is turning. It's in orbit. In order to make it fall, you'd need to break it.
(1): C14's decay product can't be C12, you'd lose atomic number there. C12 has 12 nucleons, C14 has 14 nucleons. C14's decay path is N14 (neutron -> proton + electron + antineutrino: Slashdot needs "physicscode").
(2): By ambient level, I meen "initial ratio" of C12 to C14. You need to know this. Without it, you have no idea about anything. So C14 dating assumes that the C14 level in the atmosphere was constant over time, and the crosscalibration indicates that assumption is mostly correct.
Well, no, there isn't a way.
If you put an unlimited number of all the pieces of an airplane in an unlimited number of big piles, and let an unlimited number of airplanes sweep through them, and then sweep away the piles that don't look like you want them to look like - repeat ad nauseum, and in the limit of infinite repetitions, you'll get an identical airplane, and then no, you won't be able to tell them apart. The problem is that you're looking at an end product and saying "That must be designed." I could look at a pile of dirt, study it for years, and say "that must be designed" and still be wrong. See also Cydonia on Mars.
Human timescales differ from universal timescales. Evolution is a very messy process, and produces a lot of crap. People born with gills, for instance. But, hey, I'm not exactly one to criticize: I haven't built any universes lately.
Reread my post: in the limit of the two theories that I stated, one is the direct opposite of the other.
Aliens genetically constructed the earth as their terrarium: that falls under "creationism" - instantaneous creation of Earth at some point in time in the past (or relatively instantaneous...).
Universe laid by a giant bird: Falls out of the scope of the theories, as the theories describe Earth's creation. Rewriting "Earth laid by a giant bird." Falls under "creationism" - instantaneous creation of Earth.
If you define evolution and creationism as I did, they're opposites of each other. If Earth wasn't created instantaneously at some point, it must've been created over some period in time. Likewise, if the Earth wasn't created over a period in time, it must've been created instantaneously. I didn't give you a "how". I gave you a "when".
There's a hell of a lot of data on calibration of C-14 dating. For some they used historical references, others they used tree-ring calibration. It's not far off, in most cases. If the parent to your post was trying to say that C-14 data gives dates >1 million years off, he/she's on crack: C-14 is only accurate up to 60K years or so. It's also almost definitely order-of-magnitude correct. The problem mostly stems from two sources:
:) The first one however can produce dates which drift significantly as you go farther and farther back in time, as the "C-14 timeline" will "compress" and "expand" - that is, certain stretches of "real time" will correspond to unequal portions of "C-14 time" based on the levels of C-14 in the atmosphere at those points.
1: Varying C-14 levels in the atmosphere over time (sunspots)
2: Point at which carbon-exchange ended in the object.
The first one is not that severe, honestly, and the second only applies to nonliving things. For living things we can pretty accurately assume that carbon exchange ended when it died.
Radiometric dating is very accurate if you know the ambient level throughout the period that isotope exchange was occuring, and then when the isotope exchange stopped. If you're off significantly on either one of those, you could have problems. But that's what cross-calibration is for.
Depends on your definition of "evolution" and "creationism". If you define "evolution" as the change over time of the Earth into what it is today, and "creationism" as the instantaneous creation of the Earth at some time in history, then yes, they are the direct opposites of each other, and to negate one proves the other.
You're talking about specifics of evolution (which is scientific theory) rather than the evolution mindset (which is a mindset). Debate the specifics of evolution (theory) and you'll get dogmatic response, unless you go after something which is still an open question, from the community's point of view. You can't really debate a mindset, though.
And astronomy/physics is extremely dogmatic! All science is. Try offering an alternative explanation other than the Big Bang, and we'll look at you like you're crazy (because you probably are - you can SEE the Big Bang if you look at the sky in microwave). You're talking about "offering an alternative explanation for something that was considered over and done with." In any science, you'll get a sharp response in that area. The other end, where you're talking about non-constancy of physical constants, that's ALWAYS been considered an open possibility. You can find papers on that back over a hundred years.
Doubt me on the dogmatic nature of astronomy and physics? Look for papers on alternative answers to the Higgs boson, and see if you find papers which reference them and support them. You won't. Even though the Higgs boson hasn't been found, and there're still possibilities if it can't be found, they aren't being looked at.
... actually, it assumes a flowing system, for carbon dating life with C14. Carbon-14 dating assumes that there's continual carbon exchange, and at some point the carbon exchange stopped. For a living creature, that's when it died, as it stopped breathing.
Problems in C14 dating don't make the method wrong, they make the implementation in certain aspects wrong. That's like declaring that Wien's model of the blackbody curve is wrong in the exponential tail simply because it gets the early part wrong. C14 is very accurate if you know when the carbon exchange stopped, and that'll put the age of certain things very very old.
Most of us do the research. The problem is with people who claim that a method is flawed because they found one example where it (supposedly) doesn't work. Overwhelming evidence that supports it is enough to convince logical people.
OK, short, short answer. Heh.
:)
People who believe in literal creationism (that is, literal "English" creationism - literally the process that is described in the English translation of the Bible) are taking explanations way out of context.
They should also go to Egypt and look for bread (made of grain) to fall from heaven on their heads (rather than manna, which is real), and far more amusingly, only forgive each other 490 times. After that, screw you, jackass.
The problem is that we are far, far removed from the people who read the original version of the Bible. We don't know the colloquialisms. Even scholars don't know. Even the original versions of the Bible (Hebrew) may be very far off from the true original, because we simply do not have the colloquial context. (For example: we use the word "heart" in multiple contexts, and it's difficult to discern which version we mean. There's no reason to believe that they didn't have similar concepts as well.)
I honestly wonder when people start supporting creationism. I really want one of them to explain to me what happened. What do they REALLY think happened? Genesis's account is vague - clear it up. Exactly how did God separate the Earth from the heavens? Basically, if you keep saying "How?" "How?" "How?" to someone espousing creationism, you'll get one of two answers. "He just did" or "I don't know." The response to the first is "that's not an answer", and the response to the second is "That's what I'm trying to figure out."
Here's the thing: if you can't reconcile Genesis with science in your head, you're not thinking enough. It's easy - it really is. All science does is stick a bunch of answers where Genesis is vague.
Religions answers "Who". Science answers "How". Don't people ever take journalism classes?
Did you read the article? It's less about the fact that the asteroid strike was being blown out of proportion and more about HOW it was blown out of proportion, and the dangers of overblown media hype with this sort of an issue.
Yes, we know it was overblown. Yes, we've known it for a while. But no, I did not know exactly how it happened. Apparently it's one guy who commented to the BBC in a very dangerous manner - something along the lines of "this object is the most dangerous object thus far encountered." The BBC then took this completely out of context and mediafied it.
Look, this is dangerous: it's more dangerous than the asteroid. This is the classic story of the boy who cried wolf, except in this case, it'd be better described as "the detached aloof boy who commented on a wolf-like smell in the air often and the other little boy who cried 'wolf' every time the first boy mentioned it." Media's been jumping on every factual statement that NEO scientists have been making, and people are getting to the point where any asteroid strike is going to be laughed at. This is dangerous. Very very dangerous. It's not like asteroid strikes don't happen. It's not like it wouldn't kill us. It's not like it wouldn't be very, very difficult to stop.
It is not about the apps. It's about the toolchain, and the libraries. You said it yourself:
:-)
Linux/BSD -- no problem at all. Just recompile.
But that implies a wealth of things: a working compiler that works as good and is as efficient as the old one, with as few bugs as possible. If you write the compiler from scratch, this is not going to be the case. It is not going to be as good and as efficient as one that's been worked on for an incredibly long time.
There's a wealth of information on this subject out there: take a look at AMD's presentations showing the progression of SPECint95 scores as improvements in CISC (x86) based designs completely eliminated the differences between architectures. You flat out do not get much of a performance boost from switching architectures: a well optimized design reduces any ISA to an optimal architecture.
Think about it this way. When you upgraded processors before in x86-land, the worst that could happen would be a really bizarre bug would show up that could cause strange things to happen, but for the most part, everything worked. See the F00F bug, the Pentium fdiv bug, etc. etc. If you switch processors and move from IA32 -> IA64, the whole damned OS could fall apart and not run straight from the beginning because of a compiler bug. It's an integration nightmare.
Man. Then when you think that IA64 puts a huge strain on compiler writers, it's no wonder that people look at x86-64 and say "that might not be a bad idea."
As for the die space argument you had at the end, cache is huge, decoding/translation is tiny. You're talking orders of magnitude difference here. Think about it in the reverse sense. If you had something that increased die size by, say, even 1%, and allowed backwards compatibility with absolutely tons of applications, wouldn't you do it?
... and praying that the compiler doesn't introduce a thousand new bugs. Gee, that never happened before.
Sticking with x86 means that the old compilers will work as well as they did before, and are far less likely to contain bugs than being compiled by a totally new compiler.
Honestly, I don't see why it's that bad. Slowly but surely, they're eliminating the bad portions of the x86 ISA, and everything still runs. Starting from scratch means that you need to relearn all sorts of optimization techniques.
I think you're missing the point: all you need is a compliant OS. Applications can become "compliant" on a case-by-case basis. A long mode OS can run non-long mode apps simply by clearing the L bit (cf. AMD's x86-64 whitepaper). This is basically identical to the way that the 32-bit stuff ran, except you don't have "standard 16-bit mode" available under a long mode OS. That's fine - the processor can still run the stuff, you just need to reboot. Perfect.
How long do you think it's going to be before Microsoft puts out a 64-bit Windows XP? Not long. Why? It doesn't take any time, and they get to charge people more money. Sounds like a Microsoft solution to me. Once you've got the thing running a 64 bit OS, then it's pick-and-choose 64-bit mode on an app-by-app basis.
Erm, OK, need to correct that a bit, mainly because the P4 is such a weirdo.
The P4's trace cache kindof eliminates the x86 translate penalty, because the trace segments for the long x86 instructions come from the microcode, rather than from a translation engine. In fact, if you think about it, you're really not hurt at ALL by having x86 here, because if someone wants to do one of these weird x86 instructions, well, they'd want to do it in your new ISA as well, and it'd be awkward there. The correct solution here would be "don't have the idiot programmer do that" but that's not the processor designer's fault, it's the compiler's fault for using such a clunky instruction (or the programmer's fault, for using a stupid assembly instruction).
Honestly, let processor designers go wild, and they'll come up with dozens of ways to fix a broken ISA, until it doesn't matter anymore that the ISA has stupid cruft in it, because only the "intelligent parts" remain. I think Hammer's a step in that direction as well, by increasing the number of registers, and by eliminating the x87 cruft in full 64-bit mode.