Microsoft tends to solve problems by throwing money at them, but if this article is correct, that is a flawed strategy. The excess cash allows them to keep a flawed product on the shelves (e.g. XBox) long past the point where a poorer company would be focusing on improving the product to make it match the customers needs.
I'm not sure I agree with this. As far as I can tell, the X-box is doing exactly what it was intended to do - introduce Microsoft brand awareness into a different market, and to prime that market for future Microsoft offerings. The actual profitability of the X-box itself isn't very relevant (its goal does not seem to be to make money).
Firstly, whether it's fair or not, a lot of places simply won't look at your resume for any technical position unless you have a post-secondary degree of some kind. If you have many years of experience (3 minimum), you may be able to get by on past work alone, but even then you'll be less favoured for raises and promotions because of the impression that you're less "skilled".
Secondly, going through the computer stream, the business stream, or both, in college, will give you extra perspective on where the demands of management and the coders are coming from, and how to balance their requests. You'll be able to do a better job (not all of the job is technical).
Thirdly, it gives you flexibility and mobility in your job. You're qualified for being more than just a sysadmin, so you can take other positions if there are no sysadmin jobs available or if your interests change over time. Choice is usually a good idea.
In summary, I think that college would be very valuable for you at your current career stage.
IF we had a moon colony how would a molten core compare to solar cells as an energy source?
Solar would be better.
Especially with no atmosphere or weather to degrade the incoming sunlight, solar cells work quite well.
Geothermal is a pain to work with under the best of circumstances (you can only build a large-scale plant (no small power sources)), and even if the moon has an energy-producing core (tidally kneaded or (like Earth's) radioisotope-powered), the amount of energy flowing out of it is small compared to Earth's (no volcanism or rapidly convecting mantle). This means that the yield from geothermal on the moon will under the best of conditions be much lower than on Earth.
Given that solar power is so convenient, I don't see any strong reason to use geothermal. Power storage for half a month isn't *that* hard, and if you need enough power to make storage impractical, you can put big mylar mirrors in orbit around the moon to reflect enough sunlight to supply your photocells (probably cheaper than a power cable around the equator).
NetTrek was one of three games I fondly recall from my undergrad days.
The other two were "dogfight" and "bztank". I'm told that "bztank" is still popular, but as far as I can tell the only incarnation of "dogfight" that exists is a binary-only package that runs on SGI machines.
Are either of these games still being maintained? Are either of these games distributed as source? If so, where?:)
As I understood it, the potential of zero-point energy does not lie within the extraction of the energy itself. The most promising aspect, actually, would be if we were to somehow "shield" a nucleus from this energy. Theory states that it would cause the nucleus to implode upon itself, and produce a blast that would make the H-bomb look like a firecracker.
Any scheme that extracts energy from zero-point effects, either directly or indirectly, is vulnerable to the argument I made; the possibility is what matters, as opposed to the precise mechanism.
If I understand correctly, by "shield" you mean "remove the effects of within a volume". A nucleus isn't much affected by what happens outside it. _Within_ the nucleus, the seething sea of virtual particles play a large part in keeping the nucleons bound together, but a) removing the virtual particles would cause the nucleus to fly apart, not implode, b) removing virtual particles is just a way of saying "magically cause no forces to apply", as at least the first three fundamental forces are transmitted by virtual particles, and c) good luck magically causing the fundamental forces not to apply. If we can do this, then getting free energy will be the least of the effects we could produce:).
Given current physics, yes. Just wait a while though, and we'll get Zero Point Energy working. Evidently there may be enough energy in a 1 cm^3 vacuum to boil all the worlds oceans. Much more energy than antimatter, and you don't have to take it with you, as vacuum is rather abundant.
The problem with zero-point energy is that it's at the zero point.
It's not the amount of energy bound within a system that tells you how much you can extract - it's how far above the lowest possible energy state your system is in. You can make a pretty solid argument for vacuum - even boiling with zero-point energy - being at the lowest achievable energy state ("otherwise it would have decayed to a lower state already"). If you can't make vacuum decay to a lower energy state, you can't extract any of the zero-point energy. If you _can_ make it decay, then why hasn't any of the *vast* expanse of vacuum in the universe decayed already? This would be very, very noticeable.
An analogy would be to look at chemical energy. By classical mechanics, you should be able to draw a near-infinite amount of energy out of a single hydrogen atom, just by moving the electron closer to the nucleus; the Coulomb potential well is infinitely deep (or at least far deeper than electrons normally sit, even if you assume a nucleus with measurable size). But we know that in practice the best you'll get from changing states in a hydrogen atom is about 13.6 eV (arbitrarily-close-to-free outside the potential well to the ground state, at about -13.6 eV).
The ground state (-13.6 eV) is as far as you can send an electron down into the potential well, even though the well is a lot deeper than -13.6 eV.
Similarly, by the fact that the vacuum near us hasn't decayed, you can make a pretty strong argument for the observed state of vacuum being the lowest reachable state.
Do yourself a favor and calculate how long that PCB trace would have to be to make an effective antenna. Then post an apology.
Or just look at the length of any cell phone's antenna (they do unscrew, you know) (hint: it's been smaller than your phone for a couple of generations now)
Or calculate how long a quarter or half a wavelength at 2.4 GHz is (hint: a *full* wavelength at *1* GHz is only a foot).
I don't even know where to begin. Only someone who didn't understand anything about compilers and the hinderance that unnecessary abstraction creates would make the statment that C++ is better for programming games. C++ is fine for applications that don't squeeze the last drop of performance out of a system because memory usage and overhead are considered acceptable trade-offs. But for real programming the only way to go is hand optimized C and assembly.
The bottleneck for all games for the past 5 years or so has been the graphics card, for the machines most gamers play new releases on.
The graphics libraries are already written in hand-tuned assembly where needed. This is the domain of the graphics card manufacturers (or the driver companies they contract to do it, but I digress).
I would be surprised if the CPU breaks a sweat when running game engine code, so writing it in C++ makes a _lot_ of sense, as *well-written* C++ is more modular (and thus more maintainable and extensible) than C.
Triangle transformation libraries and so forth in the engine could easily be written in inline assembly if they're under enough load to justify the obfuscation. C++ supports this too, you know.
In summary, I think your complaints about using C++ in game engine code are unfounded.
True. However semiconductor lasers are seriously cheap and getting cheaper all the time. If a reason for launching this much stuff can be found, then this is probably a better architecture. In particular if the lasers can scale to tourism payloads then we are talking something that can be funded.
...And I just finished coming from a seminar where they discussed prototype diode lasers with a 3db frequency of 30 GHz. Pulsing a diode laser isn't a problem:). You need more of them to get the same output power (since your duty cycle is less than unity and your pulse spacing is long enough that you can't consider them equivalent to CW from a heat POV), but that's just amortized into the per-flight cost like the plant cost is under any scheme. It them becomes a question of whether other benefits of a pulsed scheme provide a benefit that outweighs the added cost. (IMO, the fact that a pulsed system could be air-breathing and avoid the whole reaction mass problem is more than enough benefit to cancel the added cost).
Just spray gaseous fuel out to the focal point of the mirror
Sorry, doesn't work. When the fuel burns it forms an opaque combustion layer- and then your laser doesn't focus right. That architecture needs a pulsed laser.
And this is a problem why?
I still don't see why a pulsed solution would be impractical. Yes, you need a bigger laser installation, but so what?
Obviously a NERVA-style rocket would be totally implausible for the reasons you describe. There are other ways, of course. One example had the fuel grains encased in a ceramic materials that was very heat efficient but constrained any radioactive debris from escaping the reaction chamber. There's also the possibility of using some sort of gas or liquid sodium heat exchange system to heat an inert propellant to use as thrust.
The problem is that both of these methods decrease heat conduction and increase weight enough to make the usefulness of a nuclear drive very questionable. This was touched on in my previous post.
The heat exchanger is not a huge problem- the heat flow is comparable to the heat flow that a microprocessor heatsink sees in fact. And you have to compare this with turbopumps- with this system no turbopumps are needed; it's a laser powered pressure fed rocket in fact; with a high ISP.
The heatflow per unit area in a microprocessor heatsink is miniscule compared to the flux you'd need to drive an engine with an Isp of 600, unfortunately. You need to get your exhaust hotter than any chemical rocket can manage. I have doubts of you even being able to *use* a heatsink under these conditions, as the exhaust temperature will be hotter than the degradation/melting/boiling temperatures even for things like tungsten carbide and carbon. Rocket nozzles survive by being actively cooled by fuel coming in, which gives a blanket of cooler exhaust next to the nozzle wall. For a heat exchanger to work, your wall has to be hotter than the desired exhaust temperature.
And turbopumps aren't terribly relevant to the issue - alternate designs don't need turbopumps either.
I'm not sure that's really practical as it stands. Nobody has or can afford a pulsed laser of the required power, and nobody is planning to build one.
Exactly the same could be said for a continuously driven laser launcher. Both would require building batteries of lasers on a huge scale. Not even the laser fusion experiment facilities come close.
Both are practical to build, though the number of lasers required (and thus cost of the ground facility) will differ.
Secondly, this is purely an airbreathing design- as such it cannot make orbit [...] Thirdly it requires a laser pointing from directly below
Sure it can. You just have to accelerate tangentially or nearly tangentially for most of the trip (which increases your laser path and thus the engineering challenge, but you'd need to do this anyways to keep acceleration sane with an air-breather). Once you're in the upper atmosphere, losses due to drag on the way out are manageable (as long as mass per unit cross-sectional area of the craft is much larger than the mass per unit area of the atmosphere it plows through on the way out, you don't lose much velocity).
If you really want to use a design that carries its own fuel, you can still use this scheme. Just spray gaseous fuel out to the focal point of the mirror (you have a blast deflector right next to it, so this isn't difficult).
Ground based lasers will always be subject to thermal blooming due to atmospheric attenuation.
Interesting. Is this caused by the lasers or just natural artifacts of the atmosphere? Incidentally power is the cheap bit in the equation, and you need less of it delivered at altitude due to g-limiting anyway; so it may not matter.
Atmospheric. You have two effects happening. One is that minute particles in the atmosphere scatter the laser beam. This is unavoidable, and causes exponential attenuation over long distances. The second is that the atmosphere absorbs some of the light you're sending, and heats up. This causes optical mayhem that defocuses the beam.
Compounding the problem is the fact that you'll have to fire through a *lot* of atmosphere. Your craft needs most of its velocity to be tangential, and you want as long an acceleration path as you can get away with to keep the acceleration to something that a) you can provide and b) won't damage your cargo. This means a grazing path through the atmosphere, which means your lasers will be firing through hundreds or possibly thousands of kilometres of air (i.e. as far as you can manage).
The only practical scheme I can think of for very long distances is to have multiple stations along the flight path and to fire a converging beam, so that heating problems are only significant for the last little part of the beam path.
On a couple of other points: You'll be using a laser array, not a single laser, so the cost will be directly proportional to the power required. More power means more cost.
Also, I have doubts about a heat-exchanger system working. Throughput tends to be low compared to the power flow required to get high ISP, and a heat exchanger means a heavier craft. The most practical craft design I've seen suggested, which has flown in small-scale tests, has the bottom of the craft being a curved mirror with a central projection. The laser is focused by the mirror and heats air immediately below the central projection, which is shaped to force the air to move away from the craft.
Laser launchers are a neat idea, and avoid the problem of carrying most of your reaction mass when set up in jet mode, but there are formidable engineering problems to overcome before they're practical.
Yes, the engines would be quite different from the nuclear thermoelectric devices we've already orbitted, but the safety measures would not be. The casks containing the hot material are subjected to absolutely insane tests (burned, blown up, impacted, submerged, simulated re-entry) to prove that they won't spill material, and to date none of them have despite a wide range of circumstances.
You do realize that any NERVA-style engine that can get enough thrust to carry a craft from surface to orbit works by passing exhaust over bare fuel grains, right? (You increase weight and slow down heat transfer too much by putting a thick barrier in between - see Newton's laws of heating and cooling.)
How exactly do you propose to prevent a) fuel grains from being eroded, sending radioactive material into the exhaust stream (as was a known side effect of the only beast of this type that flew), or containment failure in event of a crash, given that there *have* to be open ports for your exhaust to flow in and out of?
RTEGs have the wonderful advantage of being able to completely enclose the radioactive materials. Groud-to-orbit nuclear rockets can't.
I hadn't realized we could reliably tweak animals' pleasure centers (which is how they "reward" the rats in the cited experiment).
How long until we can a) do the same in humans and b) do it safely enough that it becomes commonplace (legally or illegally)?
While Niven-esque "wireheading" wouldn't _solve_ the drug problem, it would certainly change the landscape (and remove a few of the nastier side effects on society).
Except that the catholic church has massive stockpiles of money and precious artifacts / etc, and is (iirc) the richest organisation in the world.
Bear in mind that it's cash flow, and not assets, that matters.
My university has hundreds of millions of dollars squirrelled away. There was great call to dip into that reserve when the province cut educational funding.
I'm glad they didn't. Those hundreds of millions of dollars are an endowment fund - they're invested, and the interest on the investments provides the university with a moderate amount of money every year *forever*. Dipping into the reserve would cripple the university in future years.
I expect that much of the RC church's wealth is similarly tied up. As I'm not their accountant, I couldn't tell you for certain.
And if you're seriously suggesting selling relics, I question your judgement. That would be like a museum whose long-term business plan was selling the contents of its exhibits to other museums. Both unsustainable, and contrary to the purpose of the institution.
In summary, I see no direct evidence of financial mismanagement or lying about needs for funds [I'm not claiming it doesn't exist; this just isn't it].
On the contrary, people try all the time, and every once in a while a new approach makes it into the mainstream (remember "New Math"?).
Anyone who could come up with a better scheme and prove that it worked would make a fortune as an educational consultant (government will throw *vast* amounts of money at this kind of thing). Nobody's succeeded yet.
Ever seen 'Sesame street'. Seems to me that kids learn stuff from that show without grades being involved.
Watched this as a kid, and loved it.
Try to teach the entire elementary school curriculum through Sesame Street. I dare you.
[And don't forget to pick up your dumptruck full of cash from government consulting contracts when you present proof to them that it works.]
Kids should be taught to care about the information. When grades are emphasized, the information becomes pointless.
While it would be nice if we could magically make kids want to learn, nobody's found a way to do this yet.
I like learning enough that after a BASc and MASc, I'm still coming back for more. But if you'd given me the chance to cut out on school when I was a kid, I'd have jumped at it (and be mopping floors right now).
Spend some time working with kids. By and large, they're selfish, lazy little bastards, with redeeming qualities that only emerge as they grow older. Until they grow up enough to gain maturer attitudes, all of the good intentions in the world won' help.
I agree that emphasizing grades (and grading in general) is an imperfect system, but it's the best one we've found so far.
[Yes, I know that a few rare kids actually do care about learning from a young age, but most don't.]
Disclaimer: Yes, I know this wasn't written by the poster. Yes, I know this was satire. Yes, believe it or not, I did find it marginally amusing.
But, I'm still going to pick apart a couple of points.
Something is wrong here. War, disease, death, destruction, hunger, filth, poverty, torture, crime, corruption, and the Ice Capades. Something is definitely wrong. This is not good work. If this is the best God can do, I am not impressed. Results like these do not belong on the résumé of a Supreme Being.
[...]
The Divine Plan. Long time ago, God made a Divine Plan. Gave it a lot of thought, decided it was a good plan, put it into practice.
According to a friend who is studying university-level theology, the Roman Catholic view is currently that there isn't a "divine plan", as that would contravene free will. The idea is that God would love to see us all happy, offers guidance etc. if we ask for it, but we are still free to screw ourselves over. This results in all of the wonderful ills that plague our civilization.
But He loves you. He loves you, and He needs money! He always needs money! He's all-powerful, all-perfect, all-knowing, and all-wise, somehow just can't handle money! Religion takes in billions of dollars, they pay no taxes, and they always need a little more.
Unfortunately, the temporal institutions that are the earthly manifestations of religion do not have access to God's bank account (must have slipped his mind). Therefore, they are bound by the same need to raise money to pay people with (administrators and the people who go out and do good works) as any other earthly organization. As they have a pretty unlimited mandate (make sure everyone on the planet is fed/clothed/etc, preferably while worshipping God), they are an unlimited sink for funds. As people are stingy bastards, they generally barely have enough money coming in to cover their infrastructure costs.
So I'm not surprised that most religious organizations say they desperately need more money. They may even be telling the truth.
Everything else even remotely related to computers has gotten drastically cheaper over the years.
I'm not sure about this.
A decent, new system has cost between $1500 and $2000 Cdn ($1000 and $1300 US) for about a decade and a half now.
You can buy a used Pentium machine for under $200, but good luck running XP on it (you run Linux, I run Linux, but most people don't, and you can't play Tribes 2 on a Pentium under any OS).
What we get for our money has gotten better, but the cost of a system has remained more or less constant (it's a market sweet-spot).
I've actually had uniformly good tech support from my cable ISP (Rogers, in Toronto, Canada).
This surprised me too.
The wait time for support can drag on to quite some length, but in all but one case, I was talking to a fully-clued person on the other end, with real ability to prod the network from their end.
The one other case was someone only marginally clued, but who was still polite and as helpful as he could manage.
It might just have been fluke, but whatever it is, I'll take it...
This is not necessarily a problem... I'm not a Linux expert but I know there are Windows API emulators that will let Windows software run under Linux. Also if Sun donates machines to you, they probably wont be trying to audit you so you can leave Solaris alone. The point is to get rid of the BSA, not closed source.
Unforuntately, WINE doesn't work perfectly by a long shot. Many (most?) of your applications either wouldn't run or would have serious problems when running.
And forget about getting vendor support for your closed-source software when you're trying to run it in a non-native environment.
IMO the only feasible solution for research, at least, would be to have universities tired of licensing fees allocate research money to producing their own Open or nearly-Open alternatives. However, they'd have to have a very good and very _visible_ reason to fork over the cash to do this.
Even in such an obvious area as total solar radiation the ratio between what the Sun is claimed to radiate (386 billion billion megawatts [seds.org]) and what the Earth is claimed to receive (4.4 x 1016 watts [nasa.gov]) seems to fly in the face of simple geometry which seems to me should have the earth intercepting one part in 1.1 billion of the Sun's radiation.
The number I keep hearing for solar energy flux is between 1 and 1.5 kW/m^2 at the Earth's distance from the sun, which gives between 1.5e17 and 2e17 watts for the whole earth. The amount that reaches the surface is less, and the amount that could be captured by any practical harnessing scheme would be much less, but I digress. This is roughly in line with the NASA numbers.
At this flux, total solar energy output is between 3e23 and 4e23 watts. SEDS claims 4e26, so they probably switched "million" and "billion" somewhere.
Digging for data on other energy systems, there is a total mess of approaches and even units used by different specialties that are going to make even a basic comparison table hard work to draw together
What gets me is conversion to/from ergs with old articles;).
My suspicion is that solar power flux dwarfs most of the mechanical potential energy stored on Earth's surface features. Earth's angular momentum holds one heck of a lot of energy, though, as does that of the earth-moon system, so tidal will work for quite a while.
Wind is recycled solar. Ditto anything involving growing crops.
Energy stored in wind at a given time can be estimated by assuming an average velocity (maybe look up the speed of the trade winds). Mass of the atmosphere is easy to calculate (about 10 tonnes per square metre of the earth's surface; it's just the atmospheric pressure).
I have no idea how much energy is stored in hydrocarbon reserves. You can probably get an upper limit by looking at the elemental abundance of carbon in the earth's crust, and assuming that the upper km is accessible.
The other big source is geothermal, which is driven by radioactive decay in the earth's core. I'm afraid I don't have numbers for the energy flux offhand, but it should be straightforward to calculate. Anything that's still fissioning now will have a long enough half-life to last for billions of years more.
Fissionables on the earth's surface will be dwarfed by geothermal, which effectively makes all radioactives on the planet available for harvesting (albeit over quite a long time).
If the moon is receding, something is pulling it away; you can't "back calculate" that because it would be some kind of idiosyncratic effect. By default, the moon would simply spiral into the earth.
Well, if you consider that the Earth/Moon system is not the only gravity well in the solar system, you might come to the conclusion that the Sun and/or Jupiter and/or any other massive object might have a cumulative pulling effect. Because the orbits and masses of these objects is known, it would be relatively easy to calculate this effect.
To address two different points in these messages:
- Why would the moon "spiral into the earth" by default? There's nothing moving it in either direction in an ideal system.
- The moon recedes from Earth because of "tidal drag". The moon and the earth each deform each others' surfaces (creating the tides that we know so well, among other things). The net effect of this is that if one or both of the bodies are spinning, you get angular momentum transferred. The earth's rotation slows down, and the angular momentum the earth loses goes into the moon's tangential motion about the earth, which pushes it into a higher orbit.
This is what caused the moon to be tidally locked to us in the first place (i.e. always showing the same face to us).
We can calculate the rate of momentum transfer, but I don't have the numbers for that off the top of my head.
Slashdot Mirror
Microsoft tends to solve problems by throwing money at them, but if this article is correct, that is a flawed strategy. The excess cash allows them to keep a flawed product on the shelves (e.g. XBox) long past the point where a poorer company would be focusing on improving the product to make it match the customers needs.
I'm not sure I agree with this. As far as I can tell, the X-box is doing exactly what it was intended to do - introduce Microsoft brand awareness into a different market, and to prime that market for future Microsoft offerings. The actual profitability of the X-box itself isn't very relevant (its goal does not seem to be to make money).
I'd strongly suggest college, for two reasons.
Firstly, whether it's fair or not, a lot of places simply won't look at your resume for any technical position unless you have a post-secondary degree of some kind. If you have many years of experience (3 minimum), you may be able to get by on past work alone, but even then you'll be less favoured for raises and promotions because of the impression that you're less "skilled".
Secondly, going through the computer stream, the business stream, or both, in college, will give you extra perspective on where the demands of management and the coders are coming from, and how to balance their requests. You'll be able to do a better job (not all of the job is technical).
Thirdly, it gives you flexibility and mobility in your job. You're qualified for being more than just a sysadmin, so you can take other positions if there are no sysadmin jobs available or if your interests change over time. Choice is usually a good idea.
In summary, I think that college would be very valuable for you at your current career stage.
IF we had a moon colony how would a molten core compare to solar cells as an energy source?
Solar would be better.
Especially with no atmosphere or weather to degrade the incoming sunlight, solar cells work quite well.
Geothermal is a pain to work with under the best of circumstances (you can only build a large-scale plant (no small power sources)), and even if the moon has an energy-producing core (tidally kneaded or (like Earth's) radioisotope-powered), the amount of energy flowing out of it is small compared to Earth's (no volcanism or rapidly convecting mantle). This means that the yield from geothermal on the moon will under the best of conditions be much lower than on Earth.
Given that solar power is so convenient, I don't see any strong reason to use geothermal. Power storage for half a month isn't *that* hard, and if you need enough power to make storage impractical, you can put big mylar mirrors in orbit around the moon to reflect enough sunlight to supply your photocells (probably cheaper than a power cable around the equator).
NetTrek was one of three games I fondly recall from my undergrad days.
:)
The other two were "dogfight" and "bztank". I'm told that "bztank" is still popular, but as far as I can tell the only incarnation of "dogfight" that exists is a binary-only package that runs on SGI machines.
Are either of these games still being maintained? Are either of these games distributed as source? If so, where?
[Google didn't help, before you ask.]
As I understood it, the potential of zero-point energy does not lie within the extraction of the energy itself. The most promising aspect, actually, would be if we were to somehow "shield" a nucleus from this energy. Theory states that it would cause the nucleus to implode upon itself, and produce a blast that would make the H-bomb look like a firecracker.
:).
Any scheme that extracts energy from zero-point effects, either directly or indirectly, is vulnerable to the argument I made; the possibility is what matters, as opposed to the precise mechanism.
If I understand correctly, by "shield" you mean "remove the effects of within a volume". A nucleus isn't much affected by what happens outside it. _Within_ the nucleus, the seething sea of virtual particles play a large part in keeping the nucleons bound together, but a) removing the virtual particles would cause the nucleus to fly apart, not implode, b) removing virtual particles is just a way of saying "magically cause no forces to apply", as at least the first three fundamental forces are transmitted by virtual particles, and c) good luck magically causing the fundamental forces not to apply. If we can do this, then getting free energy will be the least of the effects we could produce
I remain skeptical.
Given current physics, yes. Just wait a while though, and we'll get Zero Point Energy working. Evidently there may be enough energy in a 1 cm^3 vacuum to boil all the worlds oceans. Much more energy than antimatter, and you don't have to take it with you, as vacuum is rather abundant.
The problem with zero-point energy is that it's at the zero point.
It's not the amount of energy bound within a system that tells you how much you can extract - it's how far above the lowest possible energy state your system is in. You can make a pretty solid argument for vacuum - even boiling with zero-point energy - being at the lowest achievable energy state ("otherwise it would have decayed to a lower state already"). If you can't make vacuum decay to a lower energy state, you can't extract any of the zero-point energy. If you _can_ make it decay, then why hasn't any of the *vast* expanse of vacuum in the universe decayed already? This would be very, very noticeable.
An analogy would be to look at chemical energy. By classical mechanics, you should be able to draw a near-infinite amount of energy out of a single hydrogen atom, just by moving the electron closer to the nucleus; the Coulomb potential well is infinitely deep (or at least far deeper than electrons normally sit, even if you assume a nucleus with measurable size). But we know that in practice the best you'll get from changing states in a hydrogen atom is about 13.6 eV (arbitrarily-close-to-free outside the potential well to the ground state, at about -13.6 eV).
The ground state (-13.6 eV) is as far as you can send an electron down into the potential well, even though the well is a lot deeper than -13.6 eV.
Similarly, by the fact that the vacuum near us hasn't decayed, you can make a pretty strong argument for the observed state of vacuum being the lowest reachable state.
Do yourself a favor and calculate how long that PCB trace would have to be to make an effective antenna. Then post an apology.
Or just look at the length of any cell phone's antenna (they do unscrew, you know) (hint: it's been smaller than your phone for a couple of generations now)
Or calculate how long a quarter or half a wavelength at 2.4 GHz is (hint: a *full* wavelength at *1* GHz is only a foot).
I don't even know where to begin. Only someone who didn't understand anything about compilers and the hinderance that unnecessary abstraction creates would make the statment that C++ is better for programming games. C++ is fine for applications that don't squeeze the last drop of performance out of a system because memory usage and overhead are considered acceptable trade-offs. But for real programming the only way to go is hand optimized C and assembly.
The bottleneck for all games for the past 5 years or so has been the graphics card, for the machines most gamers play new releases on.
The graphics libraries are already written in hand-tuned assembly where needed. This is the domain of the graphics card manufacturers (or the driver companies they contract to do it, but I digress).
I would be surprised if the CPU breaks a sweat when running game engine code, so writing it in C++ makes a _lot_ of sense, as *well-written* C++ is more modular (and thus more maintainable and extensible) than C.
Triangle transformation libraries and so forth in the engine could easily be written in inline assembly if they're under enough load to justify the obfuscation. C++ supports this too, you know.
In summary, I think your complaints about using C++ in game engine code are unfounded.
Remind me why students can't build an interferometer, again?
My old high school had all of the required equipment (had a holography lab at one point).
True. However semiconductor lasers are seriously cheap and getting cheaper all the time. If a reason for launching this much stuff can be found, then this is probably a better architecture. In particular if the lasers can scale to tourism payloads then we are talking something that can be funded.
:). You need more of them to get the same output power (since your duty cycle is less than unity and your pulse spacing is long enough that you can't consider them equivalent to CW from a heat POV), but that's just amortized into the per-flight cost like the plant cost is under any scheme. It them becomes a question of whether other benefits of a pulsed scheme provide a benefit that outweighs the added cost. (IMO, the fact that a pulsed system could be air-breathing and avoid the whole reaction mass problem is more than enough benefit to cancel the added cost).
...And I just finished coming from a seminar where they discussed prototype diode lasers with a 3db frequency of 30 GHz. Pulsing a diode laser isn't a problem
Just spray gaseous fuel out to the focal point of the mirror
Sorry, doesn't work. When the fuel burns it forms an opaque combustion layer- and then your laser doesn't focus right. That architecture needs a pulsed laser.
And this is a problem why?
I still don't see why a pulsed solution would be impractical. Yes, you need a bigger laser installation, but so what?
Obviously a NERVA-style rocket would be totally implausible for the reasons you describe. There are other ways, of course. One example had the fuel grains encased in a ceramic materials that was very heat efficient but constrained any radioactive debris from escaping the reaction chamber. There's also the possibility of using some sort of gas or liquid sodium heat exchange system to heat an inert propellant to use as thrust.
The problem is that both of these methods decrease heat conduction and increase weight enough to make the usefulness of a nuclear drive very questionable. This was touched on in my previous post.
The heat exchanger is not a huge problem- the heat flow is comparable to the heat flow that a microprocessor heatsink sees in fact. And you have to compare this with turbopumps- with this system no turbopumps are needed; it's a laser powered pressure fed rocket in fact; with a high ISP.
The heatflow per unit area in a microprocessor heatsink is miniscule compared to the flux you'd need to drive an engine with an Isp of 600, unfortunately. You need to get your exhaust hotter than any chemical rocket can manage. I have doubts of you even being able to *use* a heatsink under these conditions, as the exhaust temperature will be hotter than the degradation/melting/boiling temperatures even for things like tungsten carbide and carbon. Rocket nozzles survive by being actively cooled by fuel coming in, which gives a blanket of cooler exhaust next to the nozzle wall. For a heat exchanger to work, your wall has to be hotter than the desired exhaust temperature.
And turbopumps aren't terribly relevant to the issue - alternate designs don't need turbopumps either.
I'm not sure that's really practical as it stands. Nobody has or can afford a pulsed laser of the required power, and nobody is planning to build one.
Exactly the same could be said for a continuously driven laser launcher. Both would require building batteries of lasers on a huge scale. Not even the laser fusion experiment facilities come close.
Both are practical to build, though the number of lasers required (and thus cost of the ground facility) will differ.
Secondly, this is purely an airbreathing design- as such it cannot make orbit [...] Thirdly it requires a laser pointing from directly below
Sure it can. You just have to accelerate tangentially or nearly tangentially for most of the trip (which increases your laser path and thus the engineering challenge, but you'd need to do this anyways to keep acceleration sane with an air-breather). Once you're in the upper atmosphere, losses due to drag on the way out are manageable (as long as mass per unit cross-sectional area of the craft is much larger than the mass per unit area of the atmosphere it plows through on the way out, you don't lose much velocity).
If you really want to use a design that carries its own fuel, you can still use this scheme. Just spray gaseous fuel out to the focal point of the mirror (you have a blast deflector right next to it, so this isn't difficult).
Ground based lasers will always be subject to thermal blooming due to atmospheric attenuation.
Interesting. Is this caused by the lasers or just natural artifacts of the atmosphere? Incidentally power is the cheap bit in the equation, and you need less of it delivered at altitude due to g-limiting anyway; so it may not matter.
Atmospheric. You have two effects happening. One is that minute particles in the atmosphere scatter the laser beam. This is unavoidable, and causes exponential attenuation over long distances. The second is that the atmosphere absorbs some of the light you're sending, and heats up. This causes optical mayhem that defocuses the beam.
Compounding the problem is the fact that you'll have to fire through a *lot* of atmosphere. Your craft needs most of its velocity to be tangential, and you want as long an acceleration path as you can get away with to keep the acceleration to something that a) you can provide and b) won't damage your cargo. This means a grazing path through the atmosphere, which means your lasers will be firing through hundreds or possibly thousands of kilometres of air (i.e. as far as you can manage).
The only practical scheme I can think of for very long distances is to have multiple stations along the flight path and to fire a converging beam, so that heating problems are only significant for the last little part of the beam path.
On a couple of other points: You'll be using a laser array, not a single laser, so the cost will be directly proportional to the power required. More power means more cost.
Also, I have doubts about a heat-exchanger system working. Throughput tends to be low compared to the power flow required to get high ISP, and a heat exchanger means a heavier craft. The most practical craft design I've seen suggested, which has flown in small-scale tests, has the bottom of the craft being a curved mirror with a central projection. The laser is focused by the mirror and heats air immediately below the central projection, which is shaped to force the air to move away from the craft.
Laser launchers are a neat idea, and avoid the problem of carrying most of your reaction mass when set up in jet mode, but there are formidable engineering problems to overcome before they're practical.
Yes, the engines would be quite different from the nuclear thermoelectric devices we've already orbitted, but the safety measures would not be. The casks containing the hot material are subjected to absolutely insane tests (burned, blown up, impacted, submerged, simulated re-entry) to prove that they won't spill material, and to date none of them have despite a wide range of circumstances.
You do realize that any NERVA-style engine that can get enough thrust to carry a craft from surface to orbit works by passing exhaust over bare fuel grains, right? (You increase weight and slow down heat transfer too much by putting a thick barrier in between - see Newton's laws of heating and cooling.)
How exactly do you propose to prevent a) fuel grains from being eroded, sending radioactive material into the exhaust stream (as was a known side effect of the only beast of this type that flew), or containment failure in event of a crash, given that there *have* to be open ports for your exhaust to flow in and out of?
RTEGs have the wonderful advantage of being able to completely enclose the radioactive materials. Groud-to-orbit nuclear rockets can't.
I hadn't realized we could reliably tweak animals' pleasure centers (which is how they "reward" the rats in the cited experiment).
How long until we can a) do the same in humans and b) do it safely enough that it becomes commonplace (legally or illegally)?
While Niven-esque "wireheading" wouldn't _solve_ the drug problem, it would certainly change the landscape (and remove a few of the nastier side effects on society).
Except that the catholic church has massive stockpiles of money and precious artifacts / etc, and is (iirc) the richest organisation in the world.
Bear in mind that it's cash flow, and not assets, that matters.
My university has hundreds of millions of dollars squirrelled away. There was great call to dip into that reserve when the province cut educational funding.
I'm glad they didn't. Those hundreds of millions of dollars are an endowment fund - they're invested, and the interest on the investments provides the university with a moderate amount of money every year *forever*. Dipping into the reserve would cripple the university in future years.
I expect that much of the RC church's wealth is similarly tied up. As I'm not their accountant, I couldn't tell you for certain.
And if you're seriously suggesting selling relics, I question your judgement. That would be like a museum whose long-term business plan was selling the contents of its exhibits to other museums. Both unsustainable, and contrary to the purpose of the institution.
In summary, I see no direct evidence of financial mismanagement or lying about needs for funds [I'm not claiming it doesn't exist; this just isn't it].
No one's trying to find better ways.
On the contrary, people try all the time, and every once in a while a new approach makes it into the mainstream (remember "New Math"?).
Anyone who could come up with a better scheme and prove that it worked would make a fortune as an educational consultant (government will throw *vast* amounts of money at this kind of thing). Nobody's succeeded yet.
Ever seen 'Sesame street'. Seems to me that kids learn stuff from that show without grades being involved.
Watched this as a kid, and loved it.
Try to teach the entire elementary school curriculum through Sesame Street. I dare you.
[And don't forget to pick up your dumptruck full of cash from government consulting contracts when you present proof to them that it works.]
Kids should be taught to care about the information. When grades are emphasized, the information becomes pointless.
While it would be nice if we could magically make kids want to learn, nobody's found a way to do this yet.
I like learning enough that after a BASc and MASc, I'm still coming back for more. But if you'd given me the chance to cut out on school when I was a kid, I'd have jumped at it (and be mopping floors right now).
Spend some time working with kids. By and large, they're selfish, lazy little bastards, with redeeming qualities that only emerge as they grow older. Until they grow up enough to gain maturer attitudes, all of the good intentions in the world won' help.
I agree that emphasizing grades (and grading in general) is an imperfect system, but it's the best one we've found so far.
[Yes, I know that a few rare kids actually do care about learning from a young age, but most don't.]
Disclaimer: Yes, I know this wasn't written by the poster. Yes, I know this was satire. Yes, believe it or not, I did find it marginally amusing.
But, I'm still going to pick apart a couple of points.
Something is wrong here. War, disease, death, destruction, hunger, filth, poverty, torture, crime, corruption, and the Ice Capades. Something is definitely wrong. This is not good work. If this is the best God can do, I am not impressed. Results like these do not belong on the résumé of a Supreme Being.
[...]
The Divine Plan. Long time ago, God made a Divine Plan. Gave it a lot of thought, decided it was a good plan, put it into practice.
According to a friend who is studying university-level theology, the Roman Catholic view is currently that there isn't a "divine plan", as that would contravene free will. The idea is that God would love to see us all happy, offers guidance etc. if we ask for it, but we are still free to screw ourselves over. This results in all of the wonderful ills that plague our civilization.
But He loves you. He loves you, and He needs money! He always needs money! He's all-powerful, all-perfect, all-knowing, and all-wise, somehow just can't handle money! Religion takes in billions of dollars, they pay no taxes, and they always need a little more.
Unfortunately, the temporal institutions that are the earthly manifestations of religion do not have access to God's bank account (must have slipped his mind). Therefore, they are bound by the same need to raise money to pay people with (administrators and the people who go out and do good works) as any other earthly organization. As they have a pretty unlimited mandate (make sure everyone on the planet is fed/clothed/etc, preferably while worshipping God), they are an unlimited sink for funds. As people are stingy bastards, they generally barely have enough money coming in to cover their infrastructure costs.
So I'm not surprised that most religious organizations say they desperately need more money. They may even be telling the truth.
Everything else even remotely related to computers has gotten drastically cheaper over the years.
I'm not sure about this.
A decent, new system has cost between $1500 and $2000 Cdn ($1000 and $1300 US) for about a decade and a half now.
You can buy a used Pentium machine for under $200, but good luck running XP on it (you run Linux, I run Linux, but most people don't, and you can't play Tribes 2 on a Pentium under any OS).
What we get for our money has gotten better, but the cost of a system has remained more or less constant (it's a market sweet-spot).
I've actually had uniformly good tech support from my cable ISP (Rogers, in Toronto, Canada).
This surprised me too.
The wait time for support can drag on to quite some length, but in all but one case, I was talking to a fully-clued person on the other end, with real ability to prod the network from their end.
The one other case was someone only marginally clued, but who was still polite and as helpful as he could manage.
It might just have been fluke, but whatever it is, I'll take it...
This is not necessarily a problem... I'm not a Linux expert but I know there are Windows API emulators that will let Windows software run under Linux. Also if Sun donates machines to you, they probably wont be trying to audit you so you can leave Solaris alone. The point is to get rid of the BSA, not closed source.
Unforuntately, WINE doesn't work perfectly by a long shot. Many (most?) of your applications either wouldn't run or would have serious problems when running.
And forget about getting vendor support for your closed-source software when you're trying to run it in a non-native environment.
IMO the only feasible solution for research, at least, would be to have universities tired of licensing fees allocate research money to producing their own Open or nearly-Open alternatives. However, they'd have to have a very good and very _visible_ reason to fork over the cash to do this.
Even in such an obvious area as total solar radiation the ratio between what the Sun is claimed to radiate (386 billion billion megawatts [seds.org]) and what the Earth is claimed to receive (4.4 x 1016 watts [nasa.gov]) seems to fly in the face of simple geometry which seems to me should have the earth intercepting one part in 1.1 billion of the Sun's radiation.
;).
:).
The number I keep hearing for solar energy flux is between 1 and 1.5 kW/m^2 at the Earth's distance from the sun, which gives between 1.5e17 and 2e17 watts for the whole earth. The amount that reaches the surface is less, and the amount that could be captured by any practical harnessing scheme would be much less, but I digress. This is roughly in line with the NASA numbers.
At this flux, total solar energy output is between 3e23 and 4e23 watts. SEDS claims 4e26, so they probably switched "million" and "billion" somewhere.
Digging for data on other energy systems, there is a total mess of approaches and even units used by different specialties that are going to make even a basic comparison table hard work to draw together
What gets me is conversion to/from ergs with old articles
My suspicion is that solar power flux dwarfs most of the mechanical potential energy stored on Earth's surface features. Earth's angular momentum holds one heck of a lot of energy, though, as does that of the earth-moon system, so tidal will work for quite a while.
Wind is recycled solar. Ditto anything involving growing crops.
Energy stored in wind at a given time can be estimated by assuming an average velocity (maybe look up the speed of the trade winds). Mass of the atmosphere is easy to calculate (about 10 tonnes per square metre of the earth's surface; it's just the atmospheric pressure).
I have no idea how much energy is stored in hydrocarbon reserves. You can probably get an upper limit by looking at the elemental abundance of carbon in the earth's crust, and assuming that the upper km is accessible.
The other big source is geothermal, which is driven by radioactive decay in the earth's core. I'm afraid I don't have numbers for the energy flux offhand, but it should be straightforward to calculate. Anything that's still fissioning now will have a long enough half-life to last for billions of years more.
Fissionables on the earth's surface will be dwarfed by geothermal, which effectively makes all radioactives on the planet available for harvesting (albeit over quite a long time).
Good luck with your search, in any event
If the moon is receding, something is pulling it away; you can't "back calculate" that because it would be some kind of idiosyncratic effect. By default, the moon would simply spiral into the earth.
Well, if you consider that the Earth/Moon system is not the only gravity well in the solar system, you might come to the conclusion that the Sun and/or Jupiter and/or any other massive object might have a cumulative pulling effect. Because the orbits and masses of these objects is known, it would be relatively easy to calculate this effect.
To address two different points in these messages:
- Why would the moon "spiral into the earth" by default? There's nothing moving it in either direction in an ideal system.
- The moon recedes from Earth because of "tidal drag". The moon and the earth each deform each others' surfaces (creating the tides that we know so well, among other things). The net effect of this is that if one or both of the bodies are spinning, you get angular momentum transferred. The earth's rotation slows down, and the angular momentum the earth loses goes into the moon's tangential motion about the earth, which pushes it into a higher orbit.
This is what caused the moon to be tidally locked to us in the first place (i.e. always showing the same face to us).
We can calculate the rate of momentum transfer, but I don't have the numbers for that off the top of my head.
So when does a computer... ...become a huge goddamned distributed-network-in-a-room?
When it scales above the number of processors you can fit on one motherboard.
Multiprocessing systems are communications-bound for most tasks. The communications network becomes more important than the processor very early on.