Re-entry friction is less of a problem if you drop straight down. Something in orbit has a very large horizontal velocity (too lazy to work out the numbers, but roughly the circumference of the earth in 90 minutes), and much of the heat of re-entry is caused by this horizontal velocity.
Orbital velocity is about 8 km/second (5 miles/second).
Energy shed into the atmosphere is roughly proprortional to the cube of the velocity, so something travelling at Mach 1.5 (about 0.5 km/second) sheds about 4000 times less energy per unit time (and generates 4000 times less heat).
Summary: Quite a bit slower, and *much* less heat generation.
While I suspect you're at the mercy of Norton et. al. for waiting for a true Linux virus scanner, there's another option that might help reduce virus damage - automatically maintaining Windows system files.
I've mainly seen this done via some netbooting variant of NT, but it could be done using Linux as well. Either on startup or at regular intervals, system and other non-data files on Windows machines are compared regularly to protected reference copies of the files. Files that don't match are overwritten. Files that are missing are replaced. Files that shouldn't be there are wiped.
The down side: Your Windows environment has to be homogeneous (including hardware). Otherwise, your administrative hassles skyrocket, because you have to maintain a separate reference copy for every variant of the installation.
The plus side: This is the only sure-fire way that I know of to protect a Windows system from corruption, be it induced by a virus or by time. From what I've seen, it works quite well.
The Problem: You're going to have a lot of fun gaining read/write access to all of the required drives remotely and securely. Read access might be manageable without opening too many holes.
Anyone feel like looking up how much data two strands of fibre can handle?
The gain-bandwidth product of the erbium lasers used for repeaters is something like 1.0e11, if I remember correctly (could be way off on this). This gives a practical limit of between 1.0e11 and 1.0e12 bps without materials improvements.
The theoretical bandwidth limit for optical carriers of any kind is the frequency of the carrier itself - somewhere in the realm of 5.0e14 Hz (for visible-light carriers). This gives a maximum theoretical data rate somewhere between 5.0e14 and (roughly) 3.0e15 bps, depending on how much power you want to dump in and how much noise is present.
Any limitations on the number of CPUs is going to be in the chipset either in the number of pins (about 100/cpu) it can support, or in internal queuing stuff in the chipset keeping track of outstanding cache probes - the bus protocol itself is refreshingly free of such stuff.
Are you sure about that? Nothing like each chip being assigned a number out of a small and fixed pool of chip IDs?
The number 14 looks very suspicious to me in this regard (2^4 - 2).
OTOH, I haven't read detailed specs on the EV6 bus, and Compaq has recently started offering SMP systems with maximum processor counts greater than 14.
In fact, they are SMP limited by the chipsets: If a chipset existed, you could run a box with 1000 Athlon processors
Actually, my understanding was that limitations in the bus protocol limited SMP machines to 14 processors, as with Alpha machines. For more than that, you use a hierarchical scheme or clustering.
PCI 64/66 would also give us somewhere to stick 1 Gbit network cards without losing most of our bandwidth.
That should be "bus bandwidth". The network card would work fine. Just don't try to use two of them in one machine, or a PCI graphics card in the same machine.
Remember AGP, and everyone bitching at the time that it wasn't needed? I bet everyone's glad that their video cards today aren't running on the PCI bus.
A viable replacement for PCI at 32 bits/33 MHz has existed for many years now - PCI at 64 bits / 66 MHz.
This has been used in workstations since long before AGP was introduced. But, instead of migrating this standard architecture down to the consumer level, they introduce their own in an attempt to capture market share.
Likewise, there's no reason for AGP 4x to exist, when PCI 64/133 has just as much bandwidth and doesn't restrict you to only one slot.
Speaking as a person who's done graphics driver work for a few years, I can say that there are many, many fun things that you could do with multiple high-speed card ports with multiple graphics cards. However, that doesn't seem to be on Intel's agenda. PCI 64/66 would also give us somewhere to stick 1 Gbit network cards without losing most of our bandwidth. If not for AGP, these ports would be standard by now.
The only problem I can think of is that the aluminum oxide coating that naturally forms on any piece of aluminum may not be reflective enough to be used as a mirror.
A good thought, but I doubt that this would be a concern. Firstly, the oxide layer is only one molecule thick (as previously mentioned), and so should be too thin to influence incident light.
Secondly, there's already good empyrical proof that aluminum works - most telescope mirrors are made by vapour-depositing aluminum on glass.
I'd been worrying about airborne dust scratching the mirror and dulling the finish after a while, but the fact that conventional optics already use it implies that this isn't a big problem.
I'd read about this mirror technique years ago, and it occurred to me that you could easily cast near-perfect parabolic mirrors by spinning molten aluminum in a shallow ceramic dish and letting it cool.
You could keep the weight down by making the dish roughly follow the curve of the mirror (with grooves where you want ribs to be). You'd cast this in an argon atmosphere to keep the aluminum from burning (reacts with oxygen, carbon dioxide, and *maybe* nitrogen at those temperatures).
The mirror would have an optically perfect finish when it set, and wouldn't corrode (aluminum oxide is impermeable to oxygen, so you get a one-molecule-thick oxide layer).
Is there something I'm missing here, or would this indeed make a good way to produce medium-sized mirrors for hobby telescopes and larger segmented telescopes?
(You can build a segmented telescope with identical mirrors; you just have to do processing to deconvolve the resulting blurry pixels. You know the point spread function, so this can be done losslessly. A group already built a cheap segmented telescope with spherical mirrors that does this.)
So, even NOT counting on compression from the incredible amount of mass, you could fit 26 million stars the mass of the sun into the "relatively tiny space".
Given that the numbers match so closely, except for the decimal place, i suspect one of two things:
1) The article writer is amazed you can fit the volume of a marble into the volume of a basketball.
or
2) The article writer put the decimal in the wrong spot, and discovered you can put volume "V" into the space of volume "V"
I vote for option 3), 4), or a combination of the two:
3) The amount of space is "tiny" compared to the amount of space taken up by stars in the rest of the galaxy. Stars are seldom packed one against the other.
4) The writer is using copy from descriptions of smaller black holes. The even horizon's radius grows in linear proportion to a black hole's mass, if I remember correctly.
This means that volume grows far faster than mass. Black holes with the mass of a mountain are smaller than an atom; a black hole the mass of the sun have a radius of about 3 km. More massive black holes, however, have less density. In fact, if the universe is closed (i.e. returning to a "Big Crunch"), it would be the perfect example of a very sparse black hole - transplant a sufficiently large chunk of it to a reasonably flat space, and an observer outside of the transplanted chunk would see an event horizon surrounding it.
VSA-100 is probably their biggest creation for a long time, but simplicity of the chip, and it's need for parallelism for multiple VSA-100s which basically amounts to SLI on the same card is suggesting that 3dfx should spend less money on those dumb commercials and spend more on actually making something good.
Actually, the modular design is a brilliant idea - it gives built-in design scalability, and gives you huge memory bandwidth gains. Memory bandwidth limits fill rate for games at the resolutions I play at, so this is a big win.
3dfx's mistake was making their individual chips sub-optimal.
The logical way of salvaging what they can is to switch to 0.15 micron (or better if they can get it) and put multiple VSA cores on one die. This gives them a higher maximum clock frequency and lower power dissipation. Have multiple memory busses running from the die (or interleave requests across one bus), and you have a card with decent processing power and enough memory bandwidth to beat the hell out of anyone else. Part count goes down when multiple cores are bundled onto one die, so the card costs a lot less too.
All of this is effectively "for free", as the R&D has already been done in the development of the Voodoo 5 series.
It remains to be seen whether 3dfx has the money left to pursue this course.
Tweaking the chips themselves wouldn't hurt, but is secondary compared to the huge benefits of the modular architecture itself.
*Sigh*. Read the Dictionary's history.
on
Hackers
·
· Score: 2
It appears that ESR basically cribbed everything he could from Hacks to write his Hacker's Dictionary.
*sigh*.
ESR is only the current maintainer of the Hacker's Dictionary. It is the merging of two works: JARGON.TXT, which had been floating around the 'net for aeons being incrementally revised by various people, and "The Hacker's Dictionary", written in 1983 by Guy Steel.
Isn't the resolution that you can define between two different states also equal to the uncertainty?
For instance if the incertainty was 5, yes I could have any of the states from 1-100, (and all the fractions inbetween) however, I couldn't tell the difference between state 4 and state 6 because I can only say that this state is state 4+-5, and the other is state 6 +-5.
Doesn't violating this break the uncertainty barrier? (I can't measure 5mV on my voltmeter, so instead I'll bump everything up to 5V and then it will tell me the difference between 5V and 5.005V)
I might be wrong, but I just got done with a 3rd year physics class and this was my understanding.
The answer is "it depends".
You can measure a particle's energy with arbitrary precision, but get progressively worse resolution on its position as you do so (due to position/momentum uncertainty).
In this case, the escape hole is the fact that the electron orbits get very large at higher energy levels. The resulting position uncertainty isn't enough to make distinguishing the states impossible, even with the fineness of the energy measurements needed.
As for your measuring apparatus, what winds up happening (if I understand correctly) is that the time required to determine the electron's energy level increases. Time to distinguish between two states is (I think) some proportionality constant times the oscillation period of the photon that would be emitted or absorbed by the electron when changing from one state to the other. For finely spaced states, this is significant.
* Infinity isn't a recognised value in the Universe.
Prove it. All I see so far is hand-waving.
It's easy to show that it's _impractical_ to build a device with an infinite number of states, but it's certainly _possible_ (if you have an infinite amount of room).
* Whilst those orbits may be "theoretically" valid, any orbit which does NOT coincide with a valid point in space (which is also quantized, and not necessarily with the same step size), is an invalid orbit and cannot be entered.
Check that high-school physics textbook. Orbital radius goes up as the square of the energy level - even at it's smallest level, it's much too large to be affected by the granularity of space.
* Any orbit which is excluded due to any other phenomina (eg: Casimir Effect) also cannot be entered.
Other forms of noise will limit practicality long before the Casimir effect does. Regardless, the casimir effect wouldn't make any of the orbits impossible. If you had enough room for the electron shell to exist, the casimir effect would be irrelevent for orbits in that shell.
The Casimir effect also wouldn't have much of an effect period; it just affects the number and wavelength of virtual photons present in a region of space. So what?
* Of the remaining orbits, any orbit which would cause the electron to shift which nucleus or other particle it is orbiting, will negate that orbit and replace it with the corresponding new orbit around the new center point.
So suspend a single atom in a magnetic trap in vacuum, as the experiment in the article almost certainly did.
This (requirement that nothing else be nearby) also still doesn't affect whether the orbit is _possible_. As I said before, measurement concerns are already known to limit how many states you can use with practical equipment.
* Exact positioning of an electron is forbidden by the Uncertainty Principle, anyway
As above - this is irrelevant. It is the uncertainty principle that _gives_ us the wavelength of the electron, among other things. The electron orbits are _definitely_ large enough for this to be a non-issue (as they're more than a wavelength in size).
Summary: I'm afraid that your objections are based on a variety of assumptions that turn out not to hold, both about the nature of the experiment described in the article and about my own arguments. If you are genuinely interested in this topic, I'd strongly suggest picking up a first-year physics textbook and browsing the sections on quantum mechanics and atomic structure. It will be well worth it.
Before you object - yes, the number of states between the ground state and ionization threshold is infinite, even with quantum mechanics. Check a high school physics or chemistry textbook, or work it out yourself from the formulae in the textboks. Valid orbits have a circumference that is an integer number of electron wavelengths (from one to infinity).
This means that what "should" be inifinite, given a purely Newtonian view of the world, will always become finite in a Quantum Mechanical view of the world.
Um, this technique is _based_ on quantum mechanics. This is clearly described in the article.
An electron orbiting an atom can be at any of an infinite number of energy levels between the ground state and the ionization threshold. The researchers have found a clever way to arbitrarily set the probability of the electron being in each of these states, simultaneously - which gives them as many bits of data as they have states. They also have a clever way of reading back out all of this state probability information.
Limits to this are based on the time it takes the states to decay back to the ground state (which affects the lifetime of the data) and the time it takes to perform the read operation (which isn't stated, but which almost certainly lengthens for the closely-spaced energy states near the ionization energy).
No limits from newtonian/quantum mechanics, just ordinary engineering tradeoffs.
First, microwaves (and indeed any EMR) affects ONLY those molecules that correspond to that wavelength.
Actually, this turns out not to be the case. Any insulating material will absorb EM radiation in the microwave range or at lower frequencies (and any conducting material will reflect it). While materials with an absorption band in the right place will absorb _more_ radiation per unit distance, you still get absorption no matter what you're sending the microwaves through.
Absorption is an exponential drop-off in intensity within the material. The rate of drop-off depends on the incoming signal's wavelength, which is why the older longer-wave cell phones aren't as bothered by walls as the new, higher-frequency (and shorter wavelength) cell phones.
For both types of phone, the wavelength is short enough that you'll still get a substantial amount of absorption within the user's head - which will have the sole effect of heating it up by a few thousanths of a degree. I'm not too worried.
I think that the licensing issue *might* be what killed it, or at least stunted its growth.
I have doubts about that. The license would have been for one specific type of fractal compression; however, the idea was known to enough people that if licensing was a big issue, several other groups would have created their own replacement based on any of a variety of algorithms. I'm sure I'm not the only hobbyist who played with my own compression programs in those days.
I think that the first poster's explanation is the most plausible. Years ago, fractal compression was the latest toy that programmers played with in their free time. Now, it wavelet compression, or something other than compression.
There will still be people playing with fractal compression in their free time. If it's useful, we may see results eventually.
Oh well I have no clue what the hell I'd make it out of
Metal whisker fibers and carbon nanotubes both have the required tensile strength, and have both been produced in the laboratory. It is not a question of the materials existing. It is a question of being able to easily and cheaply produce them in bulk.
Nanotubes were mentioned in the article. Please read it thoroughly, as it may answer other questions you may have. It also cites more technical articles, if you want more detailed information.
So, a question to all... how to you write your code so that it's flexible enough for translation, but not open to attack?
One straightforward solution - scan through the string before using it to ensure that it only has the desired number/type of arguments specified in the pattern. If you're expecting a single string argument, keep the first occurrence of "%s" intact (or add it if you need to) and change all other instances of "%" to "%%" (or remove the %foo tokens).
Here's a question for you: If all it takes is a wire mesh or steel plate on the floor of their office/ceiling of the other office to block the magnetic flux, why isn't a computer already encased in metal with a ground (via the power cable) protected?
The problem is that as soon as you have wires leading into and out of the shell, your shell becomes almost completely ineffective. You'd have great trouble avoiding this, as you need things like power cables entering the computer.
Also, with the metal plate/mesh solution, how do you deal with flux wrapping around the plate?
There are a couple of effects that work in your favour for this. Firstly, the high frequency components of the noise won't diffract around *too* much. They're the ones that will couple the most strongly to electronics, and so the ones that would otherwise cause the most damage. Secondly, even if the low-frequency components _do_ diffract around the edge and reach your equipment, they've still been spreading out the whole time (diffracting over a wide angle range), so your equipment is still "farther away" from the source of the interference.
If you used metal mesh, aren't you then just creating a huge inductor on the floor? Inductors work by the change in magnetic flux going through loops. This induces a current acting opposite to the magnetic flux. The bigger the change in flux, the stronger the reactant current will be.
However, the reaction currents act to _cancel_ the imposed field.
A mesh (or a sheet with holes in it) can block most noise components with wavelengths substantially larger than the hole size. You can consider a solid sheet to be the limiting case as hole size goes to zero.
Even in a sheet, you'll have currents around the edge, and other circular currents within the sheet if the imposed magnetic field isn't uniform. Using a mesh just imposes a minimum size on these current circles.
The _lower_ limit to frequency blocked is governed both by diffraction (as you pointed out) and by the fact that your plate isn't an ideal superconductor. When the wavelength of the noise is substantially larger than the size of the plate, diffraction effects will become severe (though you still have _some_ benefit, as noted above). When the frequency drops to the point where the magnitude of the resistance of the current paths within the plate is substantially greater than that of the inductive reactance, the plate (or mesh) will similarly be ineffective.
This is actually a fascinating topic to think about.
I was wondering how they can tell the difference between a new star, and this star (these stars??). The article says it is behaving in the same manner, so how can they tell?
Spectroscopy would be one way. If the star pair is rich in helium or heavy elements and the surrounding nebula isn't, that would indicate that the stars have been burning for quite some time.
Environment is another way. If the star pair is inside a star-forming nebula, then there's a decent chance that it's young. No nebula, and it's probably old.
Structure is another. If it's confirmed that one of the pair is a white dwarf, then it's most likely an old binary system (alternative is a protostar that captured a white dwarf). White dwarf stars are what you get when a star the size of the sun exhausts its fuel (after the red giant stages).
I have no idea which technique of the above, if any, was used for the star pair in question. The article didn't go into much detail.
Slashdot Mirror
Re-entry friction is less of a problem if you drop straight down. Something in orbit has a very large horizontal velocity (too lazy to work out the numbers, but roughly the circumference of the earth in 90 minutes), and much of the heat of re-entry is caused by this horizontal velocity.
Orbital velocity is about 8 km/second (5 miles/second).
Energy shed into the atmosphere is roughly proprortional to the cube of the velocity, so something travelling at Mach 1.5 (about 0.5 km/second) sheds about 4000 times less energy per unit time (and generates 4000 times less heat).
Summary: Quite a bit slower, and *much* less heat generation.
While I suspect you're at the mercy of Norton et. al. for waiting for a true Linux virus scanner, there's another option that might help reduce virus damage - automatically maintaining Windows system files.
I've mainly seen this done via some netbooting variant of NT, but it could be done using Linux as well. Either on startup or at regular intervals, system and other non-data files on Windows machines are compared regularly to protected reference copies of the files. Files that don't match are overwritten. Files that are missing are replaced. Files that shouldn't be there are wiped.
The down side: Your Windows environment has to be homogeneous (including hardware). Otherwise, your administrative hassles skyrocket, because you have to maintain a separate reference copy for every variant of the installation.
The plus side: This is the only sure-fire way that I know of to protect a Windows system from corruption, be it induced by a virus or by time. From what I've seen, it works quite well.
The Problem: You're going to have a lot of fun gaining read/write access to all of the required drives remotely and securely. Read access might be manageable without opening too many holes.
Revar decided to GPL Fuzzball 6 and put it up on SourceForge: https://sourceforge.net/projects/fbmuck/
Fuzzball is a variant of TinyMUCK that, among other things, hosts FurryMUCK's 8000+ registered users (though FurryMUCK is still using version 5.x).
Anyone feel like looking up how much data two strands of fibre can handle?
The gain-bandwidth product of the erbium lasers used for repeaters is something like 1.0e11, if I remember correctly (could be way off on this). This gives a practical limit of between 1.0e11 and 1.0e12 bps without materials improvements.
The theoretical bandwidth limit for optical carriers of any kind is the frequency of the carrier itself - somewhere in the realm of 5.0e14 Hz (for visible-light carriers). This gives a maximum theoretical data rate somewhere between 5.0e14 and (roughly) 3.0e15 bps, depending on how much power you want to dump in and how much noise is present.
as the two spacecraft hurtled at 250 miles above Kazakhstan at a rate of 50 miles a second
Not to pick nits (ok, yes to pick nits), orbital velocity is actually about 5 miles per second. Someone added an extra zero here.
Any limitations on the number of CPUs is going to be in the chipset either in the number of pins (about 100/cpu) it can support, or in internal queuing stuff in the chipset keeping track of outstanding cache probes - the bus protocol itself is refreshingly free of such stuff.
Are you sure about that? Nothing like each chip being assigned a number out of a small and fixed pool of chip IDs?
The number 14 looks very suspicious to me in this regard (2^4 - 2).
OTOH, I haven't read detailed specs on the EV6 bus, and Compaq has recently started offering SMP systems with maximum processor counts greater than 14.
In fact, they are SMP limited by the chipsets: If a chipset existed, you could run a box with 1000 Athlon processors
Actually, my understanding was that limitations in the bus protocol limited SMP machines to 14 processors, as with Alpha machines. For more than that, you use a hierarchical scheme or clustering.
PCI 64/66 would also give us somewhere to stick 1 Gbit network cards without losing most of our bandwidth.
That should be "bus bandwidth". The network card would work fine. Just don't try to use two of them in one machine, or a PCI graphics card in the same machine.
Remember AGP, and everyone bitching at the time that it wasn't needed? I bet everyone's glad that their video cards today aren't running on the PCI bus.
A viable replacement for PCI at 32 bits/33 MHz has existed for many years now - PCI at 64 bits / 66 MHz.
This has been used in workstations since long before AGP was introduced. But, instead of migrating this standard architecture down to the consumer level, they introduce their own in an attempt to capture market share.
Likewise, there's no reason for AGP 4x to exist, when PCI 64/133 has just as much bandwidth and doesn't restrict you to only one slot.
Speaking as a person who's done graphics driver work for a few years, I can say that there are many, many fun things that you could do with multiple high-speed card ports with multiple graphics cards. However, that doesn't seem to be on Intel's agenda. PCI 64/66 would also give us somewhere to stick 1 Gbit network cards without losing most of our bandwidth. If not for AGP, these ports would be standard by now.
The only problem I can think of is that the aluminum oxide coating that naturally forms on any piece of aluminum may not be reflective enough to be used as a mirror.
A good thought, but I doubt that this would be a concern. Firstly, the oxide layer is only one molecule thick (as previously mentioned), and so should be too thin to influence incident light.
Secondly, there's already good empyrical proof that aluminum works - most telescope mirrors are made by vapour-depositing aluminum on glass.
I'd been worrying about airborne dust scratching the mirror and dulling the finish after a while, but the fact that conventional optics already use it implies that this isn't a big problem.
I'd read about this mirror technique years ago, and it occurred to me that you could easily cast near-perfect parabolic mirrors by spinning molten aluminum in a shallow ceramic dish and letting it cool.
You could keep the weight down by making the dish roughly follow the curve of the mirror (with grooves where you want ribs to be). You'd cast this in an argon atmosphere to keep the aluminum from burning (reacts with oxygen, carbon dioxide, and *maybe* nitrogen at those temperatures).
The mirror would have an optically perfect finish when it set, and wouldn't corrode (aluminum oxide is impermeable to oxygen, so you get a one-molecule-thick oxide layer).
Is there something I'm missing here, or would this indeed make a good way to produce medium-sized mirrors for hobby telescopes and larger segmented telescopes?
(You can build a segmented telescope with identical mirrors; you just have to do processing to deconvolve the resulting blurry pixels. You know the point spread function, so this can be done losslessly. A group already built a cheap segmented telescope with spherical mirrors that does this.)
Under Linux I found everything I need to do the same, except for the resampling step.
"man convert" lists "MPEG" as a supported file extension. Have you tried using "convert" to rescale it?
"convert" is part of the ImageMagick utility package, and is included with most Linux distributions.
So, even NOT counting on compression from the incredible amount of mass, you could fit 26 million stars the mass of the sun into the "relatively tiny space".
Given that the numbers match so closely, except for the decimal place, i suspect one of two things:
1) The article writer is amazed you can fit the volume of a marble into the volume of a basketball.
or
2) The article writer put the decimal in the wrong spot, and discovered you can put volume "V" into the space of volume "V"
I vote for option 3), 4), or a combination of the two:
3) The amount of space is "tiny" compared to the amount of space taken up by stars in the rest of the galaxy. Stars are seldom packed one against the other.
4) The writer is using copy from descriptions of smaller black holes. The even horizon's radius grows in linear proportion to a black hole's mass, if I remember correctly.
This means that volume grows far faster than mass. Black holes with the mass of a mountain are smaller than an atom; a black hole the mass of the sun have a radius of about 3 km. More massive black holes, however, have less density. In fact, if the universe is closed (i.e. returning to a "Big Crunch"), it would be the perfect example of a very sparse black hole - transplant a sufficiently large chunk of it to a reasonably flat space, and an observer outside of the transplanted chunk would see an event horizon surrounding it.
VSA-100 is probably their biggest creation for a long time, but simplicity of the chip, and it's need for parallelism for multiple VSA-100s which basically amounts to SLI on the same card is suggesting that 3dfx should spend less money on those dumb commercials and spend more on actually making something good.
Actually, the modular design is a brilliant idea - it gives built-in design scalability, and gives you huge memory bandwidth gains. Memory bandwidth limits fill rate for games at the resolutions I play at, so this is a big win.
3dfx's mistake was making their individual chips sub-optimal.
The logical way of salvaging what they can is to switch to 0.15 micron (or better if they can get it) and put multiple VSA cores on one die. This gives them a higher maximum clock frequency and lower power dissipation. Have multiple memory busses running from the die (or interleave requests across one bus), and you have a card with decent processing power and enough memory bandwidth to beat the hell out of anyone else. Part count goes down when multiple cores are bundled onto one die, so the card costs a lot less too.
All of this is effectively "for free", as the R&D has already been done in the development of the Voodoo 5 series.
It remains to be seen whether 3dfx has the money left to pursue this course.
Tweaking the chips themselves wouldn't hurt, but is secondary compared to the huge benefits of the modular architecture itself.
It appears that ESR basically cribbed everything he could from Hacks to write his Hacker's Dictionary.
*sigh*.
ESR is only the current maintainer of the Hacker's Dictionary. It is the merging of two works: JARGON.TXT, which had been floating around the 'net for aeons being incrementally revised by various people, and "The Hacker's Dictionary", written in 1983 by Guy Steel.
This predates the publication of "Hackers".
See http://www.tuxedo.org/~esr/jargon/jargtxt.html for some of this.
Isn't the resolution that you can define between two different states also equal to the uncertainty?
For instance if the incertainty was 5, yes I could have any of the states from 1-100, (and all the fractions inbetween) however, I couldn't tell the difference between state 4 and state 6 because I can only say that this state is state 4+-5, and the other is state 6 +-5.
Doesn't violating this break the uncertainty barrier? (I can't measure 5mV on my voltmeter, so instead I'll bump everything up to 5V and then it will tell me the difference between 5V and 5.005V)
I might be wrong, but I just got done with a 3rd year physics class and this was my understanding.
The answer is "it depends".
You can measure a particle's energy with arbitrary precision, but get progressively worse resolution on its position as you do so (due to position/momentum uncertainty).
In this case, the escape hole is the fact that the electron orbits get very large at higher energy levels. The resulting position uncertainty isn't enough to make distinguishing the states impossible, even with the fineness of the energy measurements needed.
As for your measuring apparatus, what winds up happening (if I understand correctly) is that the time required to determine the electron's energy level increases. Time to distinguish between two states is (I think) some proportionality constant times the oscillation period of the photon that would be emitted or absorbed by the electron when changing from one state to the other. For finely spaced states, this is significant.
Ok, I'll take the bait.
* Infinity isn't a recognised value in the Universe.
Prove it. All I see so far is hand-waving.
It's easy to show that it's _impractical_ to build a device with an infinite number of states, but it's certainly _possible_ (if you have an infinite amount of room).
* Whilst those orbits may be "theoretically" valid, any orbit which does NOT coincide with a valid point in space (which is also quantized, and not necessarily with the same step size), is an invalid orbit and cannot be entered.
Check that high-school physics textbook. Orbital radius goes up as the square of the energy level - even at it's smallest level, it's much too large to be affected by the granularity of space.
* Any orbit which is excluded due to any other phenomina (eg: Casimir Effect) also cannot be entered.
Other forms of noise will limit practicality long before the Casimir effect does. Regardless, the casimir effect wouldn't make any of the orbits impossible. If you had enough room for the electron shell to exist, the casimir effect would be irrelevent for orbits in that shell.
The Casimir effect also wouldn't have much of an effect period; it just affects the number and wavelength of virtual photons present in a region of space. So what?
* Of the remaining orbits, any orbit which would cause the electron to shift which nucleus or other particle it is orbiting, will negate that orbit and replace it with the corresponding new orbit around the new center point.
So suspend a single atom in a magnetic trap in vacuum, as the experiment in the article almost certainly did.
This (requirement that nothing else be nearby) also still doesn't affect whether the orbit is _possible_. As I said before, measurement concerns are already known to limit how many states you can use with practical equipment.
* Exact positioning of an electron is forbidden by the Uncertainty Principle, anyway
As above - this is irrelevant. It is the uncertainty principle that _gives_ us the wavelength of the electron, among other things. The electron orbits are _definitely_ large enough for this to be a non-issue (as they're more than a wavelength in size).
Summary: I'm afraid that your objections are based on a variety of assumptions that turn out not to hold, both about the nature of the experiment described in the article and about my own arguments. If you are genuinely interested in this topic, I'd strongly suggest picking up a first-year physics textbook and browsing the sections on quantum mechanics and atomic structure. It will be well worth it.
Before you object - yes, the number of states between the ground state and ionization threshold is infinite, even with quantum mechanics. Check a high school physics or chemistry textbook, or work it out yourself from the formulae in the textboks. Valid orbits have a circumference that is an integer number of electron wavelengths (from one to infinity).
This means that what "should" be inifinite, given a purely Newtonian view of the world, will always become finite in a Quantum Mechanical view of the world.
Um, this technique is _based_ on quantum mechanics. This is clearly described in the article.
An electron orbiting an atom can be at any of an infinite number of energy levels between the ground state and the ionization threshold. The researchers have found a clever way to arbitrarily set the probability of the electron being in each of these states, simultaneously - which gives them as many bits of data as they have states. They also have a clever way of reading back out all of this state probability information.
Limits to this are based on the time it takes the states to decay back to the ground state (which affects the lifetime of the data) and the time it takes to perform the read operation (which isn't stated, but which almost certainly lengthens for the closely-spaced energy states near the ionization energy).
No limits from newtonian/quantum mechanics, just ordinary engineering tradeoffs.
First, microwaves (and indeed any EMR) affects ONLY those molecules that correspond to that wavelength.
Actually, this turns out not to be the case. Any insulating material will absorb EM radiation in the microwave range or at lower frequencies (and any conducting material will reflect it). While materials with an absorption band in the right place will absorb _more_ radiation per unit distance, you still get absorption no matter what you're sending the microwaves through.
Absorption is an exponential drop-off in intensity within the material. The rate of drop-off depends on the incoming signal's wavelength, which is why the older longer-wave cell phones aren't as bothered by walls as the new, higher-frequency (and shorter wavelength) cell phones.
For both types of phone, the wavelength is short enough that you'll still get a substantial amount of absorption within the user's head - which will have the sole effect of heating it up by a few thousanths of a degree. I'm not too worried.
I think that the licensing issue *might* be what killed it, or at least stunted its growth.
I have doubts about that. The license would have been for one specific type of fractal compression; however, the idea was known to enough people that if licensing was a big issue, several other groups would have created their own replacement based on any of a variety of algorithms. I'm sure I'm not the only hobbyist who played with my own compression programs in those days.
I think that the first poster's explanation is the most plausible. Years ago, fractal compression was the latest toy that programmers played with in their free time. Now, it wavelet compression, or something other than compression.
There will still be people playing with fractal compression in their free time. If it's useful, we may see results eventually.
Oh well I have no clue what the hell I'd make it out of
Metal whisker fibers and carbon nanotubes both have the required tensile strength, and have both been produced in the laboratory. It is not a question of the materials existing. It is a question of being able to easily and cheaply produce them in bulk.
Nanotubes were mentioned in the article. Please read it thoroughly, as it may answer other questions you may have. It also cites more technical articles, if you want more detailed information.
So, a question to all... how to you write your code so that it's flexible enough for translation, but not open to attack?
One straightforward solution - scan through the string before using it to ensure that it only has the desired number/type of arguments specified in the pattern. If you're expecting a single string argument, keep the first occurrence of "%s" intact (or add it if you need to) and change all other instances of "%" to "%%" (or remove the %foo tokens).
Here's a question for you: If all it takes is a wire mesh or steel plate on the floor of their office/ceiling of the other office to block the magnetic flux, why isn't a computer already encased in metal with a ground (via the power cable) protected?
The problem is that as soon as you have wires leading into and out of the shell, your shell becomes almost completely ineffective. You'd have great trouble avoiding this, as you need things like power cables entering the computer.
Also, with the metal plate/mesh solution, how do you deal with flux wrapping around the plate?
There are a couple of effects that work in your favour for this. Firstly, the high frequency components of the noise won't diffract around *too* much. They're the ones that will couple the most strongly to electronics, and so the ones that would otherwise cause the most damage. Secondly, even if the low-frequency components _do_ diffract around the edge and reach your equipment, they've still been spreading out the whole time (diffracting over a wide angle range), so your equipment is still "farther away" from the source of the interference.
If you used metal mesh, aren't you then just creating a huge inductor on the floor? Inductors work by the change in magnetic flux going through loops. This induces a current acting opposite to the magnetic flux. The bigger the change in flux, the stronger the reactant current will be.
However, the reaction currents act to _cancel_ the imposed field.
A mesh (or a sheet with holes in it) can block most noise components with wavelengths substantially larger than the hole size. You can consider a solid sheet to be the limiting case as hole size goes to zero.
Even in a sheet, you'll have currents around the edge, and other circular currents within the sheet if the imposed magnetic field isn't uniform. Using a mesh just imposes a minimum size on these current circles.
The _lower_ limit to frequency blocked is governed both by diffraction (as you pointed out) and by the fact that your plate isn't an ideal superconductor. When the wavelength of the noise is substantially larger than the size of the plate, diffraction effects will become severe (though you still have _some_ benefit, as noted above). When the frequency drops to the point where the magnitude of the resistance of the current paths within the plate is substantially greater than that of the inductive reactance, the plate (or mesh) will similarly be ineffective.
This is actually a fascinating topic to think about.
I was wondering how they can tell the difference between a new star, and this star (these stars??). The article says it is behaving in the same manner, so how can they tell?
Spectroscopy would be one way. If the star pair is rich in helium or heavy elements and the surrounding nebula isn't, that would indicate that the stars have been burning for quite some time.
Environment is another way. If the star pair is inside a star-forming nebula, then there's a decent chance that it's young. No nebula, and it's probably old.
Structure is another. If it's confirmed that one of the pair is a white dwarf, then it's most likely an old binary system (alternative is a protostar that captured a white dwarf). White dwarf stars are what you get when a star the size of the sun exhausts its fuel (after the red giant stages).
I have no idea which technique of the above, if any, was used for the star pair in question. The article didn't go into much detail.