You recall wrong: Linux doesn't use any assembly syntax (unless you mean the Linux source code, which indeed uses AT&T syntax in the places where it uses assembly). The assembler syntax you use depends entirely on the assembler you use. If you use gas (which you also do if you use gcc inline assembly), you of course use AT&T syntax. However, if you use nasm, you use Intel syntax (or something very close). Of course, the assembler isn't part of Linux either.
You could have an OS that's compatible with every piece of hardware and software in existence, but Joe User will not want it if it takes an 8 year degree in computer science to figure out how to change directories.
I bet 99% of all people using Linux don't know how to change the current directory under Linux (on x86 it's: Load register eax with 12, load register ebx with pointer to zero-terminated string naming the new directory, call int 80h). But that's OK, because the user usually doesn't have to know it. Instead he interacts with some piece of software which does all this for him, be it the shell (where he'd type cddirectory), or some file manager (where he probably would klick or doubleclick on a symbol representing the directory of choice; although that probably won't actually result in a change of directory, but just in the display of the desired directory; but then, the user couldn't care less how the functionality is implemented under the hood).
You don't want to tell me that sending gzipped XML is more reliable than anything else, do you? Compressed data is the absolutely worst you can send over an unreliable link. You don't have any advantage if what you compressed is XML. And of course, as someone else already noted, if you need redundancy for reliability, error correction codes are almost certainly the better choice anyway.
Don't get me wrong, XML is great for what it was originally meant for, which is markup (hey, it's even in its name: eXtensible Markup Language!) It's only the misuse as general data structure language which makes it bad.
Re:I don't understand...
on
The Future of XML
·
· Score: 2, Insightful
-Easily compressed (in transit or stored)
Which just means that it has lots of redundancy. Or, as one might call it, bloat.
Don't stop at the processor level. The fundamental laws of physics already contain signs of corporate lock-in. The No-cloning feature of quantum mechanics clearly is a sign of DRM built into the fundamental laws of the universe. And the inner workings of about everything we use is tied to the exact laws of the universe we are in. Therefore you have to start at the very beginning: First build your own universe!
What they are actually thinking of is the wireless firmware, which is a closed-source binary blob loaded onto the wireless hardware on system startup. My (admittedly limited) understanding of the situation is that while the driver runs on the main CPU, the firmware runs only on the wireless processor and thus can't tamper with (e.g.) operating system memory protection. So insisting on having the source to the wireless firmware is something like insisting having on the circuit diagram to your printer -- sure, the manufacturer could sneak in some malicious behavior, but the damage is limited to that device.
If you want OSS for security reasons, your argument is reasonable. However RMS doesn't care about security (well, probably he does, but it's not the reason he founded the FSF). For him, it's a morality question that software has to be Free. Since the firmware clearly is software, it clearly is covered by his philosophy.
I think you are right that a negative mass would accelerate in the opposite direction from an applied force, but in general relativity gravitation is not a force field, it is curvature of space. I'm not about to try to solve the field equations, but I think that it is reasonable to assume that negative mass would accelerate away from positive mass.
No, it's not reasonable. In GR, a test mass follows the geodesics of spacetime (assuming no non-gravitational force occurs). The test particle mass (whether positive or negative) doesn't even enter the equation of motion (which is just the geodesic equation).
Think of the rubber-sheet analogy, with the negative masses dimpling the sheet upward instead of downward like the positive masses. Which means negative masses will repell other masses (whether positive or negative). But the movement of the mass in the dwell made by the other mass isn't affected. Note that also time will be accelerated instead of slowed down near a negative mass. It also won't give you an event horizon (thus you cannot make a negative black hole).
First let's consider the simple case of a 1 ton positve mass and a 1 ton negative mass placed at rest 100m apart in an empty universe. I agree that under your classical gravitation model the result will be as you say: both masses go shooting off in the direction of the positive mass. Very strange.
Under GR, however, the masses will behave as one might expect: the two masses accelerate off in opposite directions.
No. But I invite you to prove the opposite:-)
Now let's add the rod, but let's use a simple one: equal electric charges on each mass sufficient to exactly equal the gravitational "force" between the masses.
Ok. I guess we can neglect the gravitational effect of the electromagnetic field here.
Consider the case where the charges are both positive (or both negative). For your classical model
Nitpick: You mean Newtonian model; GR also is a classical theory (as opposed to a quantum theory).
the result is the same as with no charge but twice as fast: the positive mass is accelerated away from the negative mass by both the gravitational and electric fields, while the the negative mass reacts to both forces in its contrary way and follows. Both energy and momentum are conserved.
And so is for the GR case.
For the GR model the positive mass behaves as above but the negative mass is accelerated away from positive mass by gravity and toward it by the reversed force of the electric field. As a result, it stands still. Energy is conserved because the acceleration of the positive mass is at the expense of gravitational and electrical potential energy, but we seem to have a momentum problem.
No. The GR case behaves like the Newtonian case. Except that in the GR case, there isn't really a gravitational potential. Only spacetime curvature.
Now to the "rod": make the charge on one mass positive and the other negative.
For both models the positive mass will stand still as the gravitational and electric forces on it balance. For the classical model the negative mass also stands still as both forces are reversed and therefor still balance. For the GR model the negative mass accelerates away under the force of negative gravity and reversed electrostatic attraction. The negative mass acquires negative energy as it goes, balanced by the increase in electrical and gravitational potential energy. We still have a momentum problem, however.
Again, the GR will reproduce the Newtonian result (modulo relativistic corrections, but those should be negligible for the given masses and distances).
As we must at all costs avoid offending Emmy Noether, it looks like Newton wins this one.
Well, I've got bad news for you: GR does in general violate energy conservation!
Doesn't matter: A positive test mass will feel a force away from negative earth, which accelerates it away, while a negative test mass will feel a force toward negative earth, which of course also accelerates it away. The equivalence principle still holds.
Not at all. Imagine an object of negative mass orbiting around earth (assuming its mass is small enough to not have a measurable effect on earth's motion). Since the mass is negative, it will feel a repulsive force from earth (which itself of course still has positive mass), but the force away from earth will cause an acceleration towards earth, just of the same magnitude as a positive-mass object would have. The mass cancels out of the equation, no matter which sign it has.
If that weren't the case, negative mass wouldn't be compatible with General Relativity (which has the equivalence principle "built in"), and would therefore be useless in any GR-based considerations (and you need GR for wormholes).
No, for negative mass (unlike to negative charge), the momentum would be the opposite of the velocity (because in p=mv, m is negative). Which means, if you apply a force in one direction, the acceleration would go in the opposite direction. That is, while the force would indeed be repulsive, and the positive mass would indeed be accelerated away from the negative one, the "repulsive" force on the negative mass would cause an acceleration towards the positive mass. Thus both would accelerate in the same direction.
However, the OP was wrong in that the first law of thermodynamics (energy conservation) would be broken: An object with negative mass would also have negative kinetic energy; in the accelerating rod, the total energy would therefore always add up to zero, no matter how fast it is.
However, it would allow to break the second law of thermodynamics: Since the energy wouldn't have a lower bound, negative matter would perpetually "suck energy"; this "infinite energy sink" could be used to build a PM2 by simply putting a carnot machine in between the "negative matter" and the normal-matter surrounding. The "negative matter" would take the place of the cold reservoir (which, due to the missing lower energy bound, would never heat up).
It is of course well known that careless tagging costs lives, but the full scale of the problem is not always appreciated.
For instance, at the very moment that a Slashdotter tagged "whatcouldpossiblygowrong," a freak wormhole opened up in the fabric of the space-time continuum and carried his words far far back in time across almost infinite reaches of space to a distant Galaxy where strange and warlike beings were poised on the brink of frightful interstellar battle.
The two opposing leaders were online-meeting for the last time.
A dreadful silence fell across the IRC channel as the commander of the Vl'hurgs challenged the vile creature to take back what it had written about his mother.
The creature stirred in his sickly broiling vapour, and at that very moment the word whatcouldpossiblygowrong drifted across the IRC channel.
Unfortunately, in the Vl'hurg tongue this was the most dreadful insult imaginable, and there was nothing for it but to wage terrible war for centuries.
Physics isn't just observation. If Kepler had only observed the planets, Kepler's laws wouldn't have ever materialized. All we would have would be large tables with planetary positions. We need theories in order to understand the data and make predictions which we then can, again, test again experimental data. Experimental physics is about doing the observations, while theoretical physics is about developing the theories describing the results.
And speaking of random speculation, I've often wondered why in media, a "parallel universe" is often assumed to be similar our own. Not in terms of having evil twins of everything, but rather, similar enough to even pay a visit.
Well, the "parallel universes" of the type a wormhole could lead to would actually just be continuations of our spacetime (unless some sort of new physics takes place inside of wormholes, which, assuming they actually exist, admittedly isn't unlikely).
Note that also "parallel universes" of the Everett type would be governed by the very same laws of physics as our own (indeed, some of them are even extremely similar to our own, up to containing the same people, with almost the same experiences).
Only the string theoretic "parallel universes" are physically different.
I actually do believe in parallel universes (given that our own material space is but a single brane along higher dimensions),
Well, the part in parentheses not a fact, but just a hypothesis derived from string theory, which isn't yet an experimentally confirmed theory. Sure, you may believe it (and you're surely not alone), but you should not state it as a fact (unless you qualify it with "according to string theory").
Slashdot Mirror
Indeed, he should have used "Orwell being in the state of having a large angular momentum in his ultimate disposal place" instead.
And if you don't install a GUI, you also don't interact with Linux, but with whatever shell you have installed.
Oh yes, he wants a computer. One as in the USS Enterprise NCC-1701, or maybe even one as in the Heart of Gold.
You recall wrong: Linux doesn't use any assembly syntax (unless you mean the Linux source code, which indeed uses AT&T syntax in the places where it uses assembly). The assembler syntax you use depends entirely on the assembler you use. If you use gas (which you also do if you use gcc inline assembly), you of course use AT&T syntax. However, if you use nasm, you use Intel syntax (or something very close). Of course, the assembler isn't part of Linux either.
I bet 99% of all people using Linux don't know how to change the current directory under Linux (on x86 it's: Load register eax with 12, load register ebx with pointer to zero-terminated string naming the new directory, call int 80h). But that's OK, because the user usually doesn't have to know it. Instead he interacts with some piece of software which does all this for him, be it the shell (where he'd type cd directory), or some file manager (where he probably would klick or doubleclick on a symbol representing the directory of choice; although that probably won't actually result in a change of directory, but just in the display of the desired directory; but then, the user couldn't care less how the functionality is implemented under the hood).
You don't want to tell me that sending gzipped XML is more reliable than anything else, do you? Compressed data is the absolutely worst you can send over an unreliable link. You don't have any advantage if what you compressed is XML. And of course, as someone else already noted, if you need redundancy for reliability, error correction codes are almost certainly the better choice anyway.
Don't get me wrong, XML is great for what it was originally meant for, which is markup (hey, it's even in its name: eXtensible Markup Language!) It's only the misuse as general data structure language which makes it bad.
Which just means that it has lots of redundancy. Or, as one might call it, bloat.
Don't stop at the processor level. The fundamental laws of physics already contain signs of corporate lock-in. The No-cloning feature of quantum mechanics clearly is a sign of DRM built into the fundamental laws of the universe. And the inner workings of about everything we use is tied to the exact laws of the universe we are in. Therefore you have to start at the very beginning: First build your own universe!
Well, if Germany is down, then I wonder how I'm able to connect to Slashd@%&
NO CARRIER
No, it's the Yrr.
If you want OSS for security reasons, your argument is reasonable. However RMS doesn't care about security (well, probably he does, but it's not the reason he founded the FSF). For him, it's a morality question that software has to be Free. Since the firmware clearly is software, it clearly is covered by his philosophy.
No, it's not reasonable. In GR, a test mass follows the geodesics of spacetime (assuming no non-gravitational force occurs). The test particle mass (whether positive or negative) doesn't even enter the equation of motion (which is just the geodesic equation). Think of the rubber-sheet analogy, with the negative masses dimpling the sheet upward instead of downward like the positive masses. Which means negative masses will repell other masses (whether positive or negative). But the movement of the mass in the dwell made by the other mass isn't affected. Note that also time will be accelerated instead of slowed down near a negative mass. It also won't give you an event horizon (thus you cannot make a negative black hole).
No. But I invite you to prove the opposite
Ok. I guess we can neglect the gravitational effect of the electromagnetic field here.
Nitpick: You mean Newtonian model; GR also is a classical theory (as opposed to a quantum theory).
And so is for the GR case.
No. The GR case behaves like the Newtonian case. Except that in the GR case, there isn't really a gravitational potential. Only spacetime curvature.
Again, the GR will reproduce the Newtonian result (modulo relativistic corrections, but those should be negligible for the given masses and distances).
Well, I've got bad news for you: GR does in general violate energy conservation!
Doesn't matter: A positive test mass will feel a force away from negative earth, which accelerates it away, while a negative test mass will feel a force toward negative earth, which of course also accelerates it away. The equivalence principle still holds.
Ok: That mass will be accelerated away. So?
Do you Yahoo!? No, it's Microsoft now.
:-)
SCNR
Well, I guess the developers would be happy to change to the new support company, assuming it pays them a competitive salary.
Even shorter: ping go.to
Not at all. Imagine an object of negative mass orbiting around earth (assuming its mass is small enough to not have a measurable effect on earth's motion). Since the mass is negative, it will feel a repulsive force from earth (which itself of course still has positive mass), but the force away from earth will cause an acceleration towards earth, just of the same magnitude as a positive-mass object would have. The mass cancels out of the equation, no matter which sign it has.
If that weren't the case, negative mass wouldn't be compatible with General Relativity (which has the equivalence principle "built in"), and would therefore be useless in any GR-based considerations (and you need GR for wormholes).
Of course that would violate the equivalence principle.
No, for negative mass (unlike to negative charge), the momentum would be the opposite of the velocity (because in p=mv, m is negative). Which means, if you apply a force in one direction, the acceleration would go in the opposite direction. That is, while the force would indeed be repulsive, and the positive mass would indeed be accelerated away from the negative one, the "repulsive" force on the negative mass would cause an acceleration towards the positive mass. Thus both would accelerate in the same direction.
However, the OP was wrong in that the first law of thermodynamics (energy conservation) would be broken: An object with negative mass would also have negative kinetic energy; in the accelerating rod, the total energy would therefore always add up to zero, no matter how fast it is.
However, it would allow to break the second law of thermodynamics: Since the energy wouldn't have a lower bound, negative matter would perpetually "suck energy"; this "infinite energy sink" could be used to build a PM2 by simply putting a carnot machine in between the "negative matter" and the normal-matter surrounding. The "negative matter" would take the place of the cold reservoir (which, due to the missing lower energy bound, would never heat up).
It is of course well known that careless tagging costs lives, but the full scale of the problem is not always appreciated.
For instance, at the very moment that a Slashdotter tagged "whatcouldpossiblygowrong," a freak wormhole opened up in the fabric of the space-time continuum and carried his words far far back in time across almost infinite reaches of space to a distant Galaxy where strange and warlike beings were poised on the brink of frightful interstellar battle.
The two opposing leaders were online-meeting for the last time.
A dreadful silence fell across the IRC channel as the commander of the Vl'hurgs challenged the vile creature to take back what it had written about his mother.
The creature stirred in his sickly broiling vapour, and at that very moment the word whatcouldpossiblygowrong drifted across the IRC channel.
Unfortunately, in the Vl'hurg tongue this was the most dreadful insult imaginable, and there was nothing for it but to wage terrible war for centuries.
Physics isn't just observation. If Kepler had only observed the planets, Kepler's laws wouldn't have ever materialized. All we would have would be large tables with planetary positions. We need theories in order to understand the data and make predictions which we then can, again, test again experimental data.
Experimental physics is about doing the observations, while theoretical physics is about developing the theories describing the results.
Well, the "parallel universes" of the type a wormhole could lead to would actually just be continuations of our spacetime (unless some sort of new physics takes place inside of wormholes, which, assuming they actually exist, admittedly isn't unlikely).
Note that also "parallel universes" of the Everett type would be governed by the very same laws of physics as our own (indeed, some of them are even extremely similar to our own, up to containing the same people, with almost the same experiences).
Only the string theoretic "parallel universes" are physically different.
Well, the part in parentheses not a fact, but just a hypothesis derived from string theory, which isn't yet an experimentally confirmed theory. Sure, you may believe it (and you're surely not alone), but you should not state it as a fact (unless you qualify it with "according to string theory").