I remember hearing some years ago that if everyone on the planet all walked in the same direction at once it could affect the rotation of the Earth. I've always wanted to do the calculation but I haven't bothered to find out how much force your foot applies during a typical step. Anyone know? We can figure out how much torque and therefore change in angular momentum together! Woo!
What about machines that you don't have access to the source of? My network only has 3 Linux boxes. My G/Fs laptop is Windows, my PS2 uses my connect, and so does my TiVo. I can change the Linux boxes easily enough, but the others are going to do their thing.
I think the idea of randomizing the ID in iptables is good. I bet someone will have a patch for this within days...
After reading the document (something that is rarely done among posters), it appears to me that this wouldn't be TERRIBLY hard to fix. The different machines are recognized by the sequences of IPids that are generated for the packets that are sent out. This field must be unique for each packet with the same protocal, destination, and source. This prevents the NAT from simply mangling the number in the field, making it impossible to track the number of machines.
Someone correct me if I'm wrong, but it seems to me that iptables could be updated to change the IPid of outgoing packets to a single sequence and just keep a table of old ids -> new ids. When necessary, it performs the translation. So basically it acts as a two way filter, packets behind the NAT will all have the correct id, packets beyond it will all appear as a single sequence. Would this work?
I learned this trick from the professor that taught me assembly. However, I think his reasoning for the use of the XOR trick is much better than "it takes less space." How about "it's much faster". By XORing a register with itself you don't need to pull anything from memory over the slow bus. A MOV instruction costs you precious bus cycles.
TiVo is adding support for USB->ethernet connection in April this year. It will come with the new software that all Series2 TiVo users will get.
That's when the OFFICIAL support comes out. Unofficially TiVo can use a USB->Ethernet adaptor now. You set your dialing prefix to,#401 and it will use ethernet instead of the phone line. VERY nice.
The fact that gravity decreases exponentially with distance...
Actually I wrote a paper about gravitational waves a couple months ago in my Black Holes class and I missed points because I said that the strength of gravitational waves decreases with the square of distance. This is NOT TRUE. Gravity decreases with the square of distance, gravitational waves decrease with distance. It seems weird but it's clear when you look over the equations. So actually gravitational waves are much easier to detect than the actual effects of gravity at extreme distances.
The PS2 still is hard to program for. The difference is that now there are some libraries that can be used to simplify things. In the beginning everyone was forced to do things in pure assembly (OK, ALMOST pure assembly). But now the companies that have been working on PS2 games for years have developed libraries and engines that are already optimized. Haven't you noticed that most games that come out of the same development studio have the same look and feel? Of course each game is a bit more refined, but overall stageringly similar.
It seems to be a common misconception that the PS2 has multiple CPUs. It doesn't. What it does have is a single CPU that is split up into several independantly operating units. The dual-CPU idea developed from the fact that the Emotion Engine has two vector processing units that operate almost exactly the same. These two units make up the bulk of the mathematical processing in the PS2, and must be coded separately.
All of the code I've written for them has been in assembly and the process is GRUELING. Each unit actually performs two operations at once, a lower and upper instruction. Since the ultimate goal is optimization you end up writting all your assembly and then rearranging everything so that the combination of upper and lower instructions don't step on top of each other and everything runs without any wasted clock cycles. I have heard of a few tools that have been developed to compile C into optimized VPU code, but I haven't used any and I doubt they work very well. A good camera manipulation program will only take maybe a hundred lines of assembly if it's optimized correctly, but I bet these programs spit out many many more.
(Wow, I really steered off the original topic didn't I?)
No one besides servers can use 64 bit chips right now
This is exactly what makes the Opteron an attractive processor. Rather then being simply a 64 bit proc like the Itanium, it has the ability to run legacy 32-bit instructions. This is a Good Thing. Now I can have a 64-bit proc that can still run all my old apps, but still can take advantage of the benefits of 64-bit architechure.
In fact, as I see it, the only people that won't benefit from 64-bit are Windows users. Until MS makes a 64-bit version of Windows the standard, the only people that will benefit from the Opteron will be the people that run OSes that they compiled themselves.
I'm not quite at the cap, and every time slashdot posts and astronomy article I get modded up... Here we go!
In response to your post:
1) Dark Energy: Agreed, however I think it's more likely that some unexplained phenomena is causing the acceleration of our universes expansion. I think it's folly to create a "dark energy" to explain this though. Sounds too similar to the "eather" created to explain astronomical phenomena before we knew better. My current favorite is explained using string theory, the universe is accelerating because the 3 dimensions that make it up are still expanding.
2)Water on Mars: Couldn't agree more. Or add anything for that matter.
3)The Murky, Mediocre Middle of the Milky Way: Theoretically, it's not possible to travel as fast or faster than light. Given what we know about relativity, an INFINITE amount of time would pass on Earth if you managed to somehow reach light speed. It's simply not possible (if relativity is correct of course). However, that excludes the possiblity of alternate forms of travel, such as wormholes (which exist, in theory, but are very unstable).
4)The Origin of Life: Yeah! Last time I checked this was up to biologists and Jerry Falwell!
5)Lunar Secrets: Isn't that depressing? No... it costs too much to go there. Or at least that's what NASA wants us to think.
6)Are We Alone: Of course we aren't alone, what kind of question is this?
7)The Enigmatic Sun: I still don't understand why everyone is so concerned about how the Sun works. Why is this important? Can someone shed some light?
8)Age of the Universe: I argue that until we know "the truth" about physics, we will NEVER be able to answer this question accurately.
9)Missing Planets: Computer simulations show that Neptune and Uranus shouldn't be there... I think someone needs to recognize the obvious here: the simulations are WRONG! Does everyone honestly believe that we know enough details about our system's formation to create an accurate simulation? We can't even accurately calculate the effects of friction on a car's tire (although we are close).
10)Can We Survive 2003: The Earth wouldn't look much different without any forms of erosion to cover up the scars. Um... yes it would. The atmosphere burns up almost all incoming debris, whereas the moon has no atmosphere so everything creates a crater on the surface. Tiny rocks that create shooting stars for us create craters that are several meters across on the moon.
Actually I'm citing the work of Kip Thorne, recognized by many groups and one of the most genius minds in astrophysics. Thorne's hypothesis is that in order for the ball to go through time and interact with itself, it MUST follow one of the infinite number of scenarios in which the effect leads to the cause, as is the case here. This infinite number of scenarios is one of the major problems many have with the hypothesis.
As far as your accusation of freshmen interpreting freshmen, I suggest you look into Thorne's credentials a little more before dismissing him as an unreliable source of information.
While a bit off-topic, I feel this is the perfect time to visit the idea of paradoxes and time travel. It may be argued that this can be explained by them eventually going back to 1985 and getting married, having kids, etc. This is a valid argument, but what about a more exotic situation?
Example: What if Marty from the future killed Marty from 1985? How could that happen?
Simpler example: Imagine a billiard ball that has a trajectory that takes it into a time portal that goes back in time by a small portion of a second. However, before the ball makes it to the portal, it comes out (naturally, it went back) and knocks the original ball off it's trajectory so that it never hits the portal. This situation actually has a fairly logical conclusion (believe it or not). Suppose instead that the ball was headed towards the portal, but in such a way as to miss it. However, when the ball goes through the portal (hold on a sec...) it goes back and hits itself onto a trajectory that forces it into the portal (there it is!).
I know this example is confusing, so I provided theselinks to better explainations. The second link has a nice diagram demonstrating this. Credit must be given to Kip Thorne for coming up with this solution to the famous "Grandfather" paradox.
Anyone else have any thoughts on the idea of time travel and paradoxes? I am of the opinion that these paradoxes prevent time travel from occuring. Another popular belief if that time travel is possible, but only in the forward direction. Yet another belief is that when you travel through time, you actually enter a different "universe" from our own. This theory is directly tied in to the "multiverse" theory. Any other insight?
I couldn't agree more. However, note that Mars is close to the asteroid belt. In fact, theory suggests that the moons of Mars are asteroids that were captured when they got too close. I think that suggests that Mars is more likely to be hit than other terrestrial planets. As likely as this article suggests? I don't know.
Um... check your facts. The atmospheric pressure on Mars (a direct effect of the density of the atmosphere) is approximately 1/100th of the pressure on Earth. So actually, Earth has a FAR thicker atmosphere.
I personally don't think this is any worse than ad agencies doing market research to determine which ads work and which ones won't. This is just taking it to the next level.
Don't get me wrong, I dislike advertisements as much as the next guy, but what differentiates me (and most of hte geek community) from the next guy is that fact that I know how to look at an ad and know when I should and should not listen to what's being said. When someone watching an ad is aware of the techniques used to create the ad, it's not very likely to work.
Example: The annoying beer commercials designed to associate their beer with having fun. I know that's what they are doing, so I know to ignore the commercial.
I seriously doubt any ad developed using this technique will be so effective as to hinder my ability to logically conclude whether or not the product being advertised is actually worth spending money on.
The Seattle Robotics Society has sumo competitions.
I have seen a few of these competitions in my area (Denver/Boulder, CO). All of the ones i have seen seem to follow the rules that the Seattle Robotics Society created.
but think about it, how many times have you screwed up a math problem? now how many times has you TI83? i'll take a robot's steady hand to a live doctor any day.
I would argue that a robot capable of performing heart surgery is slightly more complicated than a TI83. Let's all remember that the number of errors in a system typically goes up with the complexity.
It's good to see that such enthusiasm can be found for Linux in a 4th grade classroom. I think this is one of the areas that is commonly ignored by those of us trying to "spread the word."
My girlfriend's little brother is in 9th grade right now and every time he watches me use my computer, he is enthralled by Linux. I wonder if it's simply easier for younger people to be excited by Linux because they are more pliable. This is something that warrants exploration.
I have to disagree with this generalization. While I agree that many of the PCs in the school system are pretty much a waste of space and time, that doesn't mean they don't have a place.
At my high school (I graduated in '99), I took multiple classes about multimedia design and computer science. In fact, the Computer Science 1 class I took in high school gave me college credit which transferred easily to just about any major university in the state (Colorado).
At the same time however, there were 3 large computer labs at my high school and I recall being herded in there several times only to waste half of the class time learning completely useless software that barely demonstrated what we were supposed to learn. Given that, I think it's fair to say that computers in schools may be overhyped, but that doesn't mean they don't belong there.
I recently heard an interview with her co-host, Tyler Harcott. He was asked whether or not the junkyard is stocked and I believe he said that no parts are added to the junkyard, but an evalutation is made beforehand to determine if the challenge is possible. I get the impression that if a challenge is deemed impossible or too hard, then it is thrown out in favor of a better one.
Slashdot Mirror
This isn't news. All stars increase in luminosity (and therefor heat output) during their lives. It's just the way things work.
I remember hearing some years ago that if everyone on the planet all walked in the same direction at once it could affect the rotation of the Earth. I've always wanted to do the calculation but I haven't bothered to find out how much force your foot applies during a typical step. Anyone know? We can figure out how much torque and therefore change in angular momentum together! Woo!
What about machines that you don't have access to the source of? My network only has 3 Linux boxes. My G/Fs laptop is Windows, my PS2 uses my connect, and so does my TiVo. I can change the Linux boxes easily enough, but the others are going to do their thing.
I think the idea of randomizing the ID in iptables is good. I bet someone will have a patch for this within days...
After reading the document (something that is rarely done among posters), it appears to me that this wouldn't be TERRIBLY hard to fix. The different machines are recognized by the sequences of IPids that are generated for the packets that are sent out. This field must be unique for each packet with the same protocal, destination, and source. This prevents the NAT from simply mangling the number in the field, making it impossible to track the number of machines.
Someone correct me if I'm wrong, but it seems to me that iptables could be updated to change the IPid of outgoing packets to a single sequence and just keep a table of old ids -> new ids. When necessary, it performs the translation. So basically it acts as a two way filter, packets behind the NAT will all have the correct id, packets beyond it will all appear as a single sequence. Would this work?
I learned this trick from the professor that taught me assembly. However, I think his reasoning for the use of the XOR trick is much better than "it takes less space." How about "it's much faster". By XORing a register with itself you don't need to pull anything from memory over the slow bus. A MOV instruction costs you precious bus cycles.
TiVo is adding support for USB->ethernet connection in April this year. It will come with the new software that all Series2 TiVo users will get.
,#401 and it will use ethernet instead of the phone line. VERY nice.
That's when the OFFICIAL support comes out. Unofficially TiVo can use a USB->Ethernet adaptor now. You set your dialing prefix to
The fact that gravity decreases exponentially with distance...
Actually I wrote a paper about gravitational waves a couple months ago in my Black Holes class and I missed points because I said that the strength of gravitational waves decreases with the square of distance. This is NOT TRUE. Gravity decreases with the square of distance, gravitational waves decrease with distance. It seems weird but it's clear when you look over the equations. So actually gravitational waves are much easier to detect than the actual effects of gravity at extreme distances.
The PS2 still is hard to program for. The difference is that now there are some libraries that can be used to simplify things. In the beginning everyone was forced to do things in pure assembly (OK, ALMOST pure assembly). But now the companies that have been working on PS2 games for years have developed libraries and engines that are already optimized. Haven't you noticed that most games that come out of the same development studio have the same look and feel? Of course each game is a bit more refined, but overall stageringly similar.
It seems to be a common misconception that the PS2 has multiple CPUs. It doesn't. What it does have is a single CPU that is split up into several independantly operating units. The dual-CPU idea developed from the fact that the Emotion Engine has two vector processing units that operate almost exactly the same. These two units make up the bulk of the mathematical processing in the PS2, and must be coded separately.
All of the code I've written for them has been in assembly and the process is GRUELING. Each unit actually performs two operations at once, a lower and upper instruction. Since the ultimate goal is optimization you end up writting all your assembly and then rearranging everything so that the combination of upper and lower instructions don't step on top of each other and everything runs without any wasted clock cycles. I have heard of a few tools that have been developed to compile C into optimized VPU code, but I haven't used any and I doubt they work very well. A good camera manipulation program will only take maybe a hundred lines of assembly if it's optimized correctly, but I bet these programs spit out many many more.
(Wow, I really steered off the original topic didn't I?)
No one besides servers can use 64 bit chips right now
This is exactly what makes the Opteron an attractive processor. Rather then being simply a 64 bit proc like the Itanium, it has the ability to run legacy 32-bit instructions. This is a Good Thing. Now I can have a 64-bit proc that can still run all my old apps, but still can take advantage of the benefits of 64-bit architechure.
In fact, as I see it, the only people that won't benefit from 64-bit are Windows users. Until MS makes a 64-bit version of Windows the standard, the only people that will benefit from the Opteron will be the people that run OSes that they compiled themselves.
I'm not quite at the cap, and every time slashdot posts and astronomy article I get modded up...
Here we go!
In response to your post:
1) Dark Energy: Agreed, however I think it's more likely that some unexplained phenomena is causing the acceleration of our universes expansion. I think it's folly to create a "dark energy" to explain this though. Sounds too similar to the "eather" created to explain astronomical phenomena before we knew better. My current favorite is explained using string theory, the universe is accelerating because the 3 dimensions that make it up are still expanding.
2)Water on Mars: Couldn't agree more. Or add anything for that matter.
3)The Murky, Mediocre Middle of the Milky Way: Theoretically, it's not possible to travel as fast or faster than light. Given what we know about relativity, an INFINITE amount of time would pass on Earth if you managed to somehow reach light speed. It's simply not possible (if relativity is correct of course). However, that excludes the possiblity of alternate forms of travel, such as wormholes (which exist, in theory, but are very unstable).
4)The Origin of Life: Yeah! Last time I checked this was up to biologists and Jerry Falwell!
5)Lunar Secrets: Isn't that depressing? No... it costs too much to go there. Or at least that's what NASA wants us to think.
6)Are We Alone: Of course we aren't alone, what kind of question is this?
7)The Enigmatic Sun: I still don't understand why everyone is so concerned about how the Sun works. Why is this important? Can someone shed some light?
8)Age of the Universe: I argue that until we know "the truth" about physics, we will NEVER be able to answer this question accurately.
9)Missing Planets: Computer simulations show that Neptune and Uranus shouldn't be there... I think someone needs to recognize the obvious here: the simulations are WRONG! Does everyone honestly believe that we know enough details about our system's formation to create an accurate simulation? We can't even accurately calculate the effects of friction on a car's tire (although we are close).
10)Can We Survive 2003: The Earth wouldn't look much different without any forms of erosion to cover up the scars. Um... yes it would. The atmosphere burns up almost all incoming debris, whereas the moon has no atmosphere so everything creates a crater on the surface. Tiny rocks that create shooting stars for us create craters that are several meters across on the moon.
Actually I'm citing the work of Kip Thorne, recognized by many groups and one of the most genius minds in astrophysics. Thorne's hypothesis is that in order for the ball to go through time and interact with itself, it MUST follow one of the infinite number of scenarios in which the effect leads to the cause, as is the case here. This infinite number of scenarios is one of the major problems many have with the hypothesis.
As far as your accusation of freshmen interpreting freshmen, I suggest you look into Thorne's credentials a little more before dismissing him as an unreliable source of information.
I fear the same thing will happen with the last Matrix movie.
The difference here however is that the Matrix has always been planned as a trilogy.
Usually when they make two movies at once and release them so close together the last one sucks.
What other examples are there? Are you suggesting that the same fate will fall upon the Lord of the Rings, in which 3 movies were all shot at once?
While a bit off-topic, I feel this is the perfect time to visit the idea of paradoxes and time travel. It may be argued that this can be explained by them eventually going back to 1985 and getting married, having kids, etc. This is a valid argument, but what about a more exotic situation?
Example: What if Marty from the future killed Marty from 1985? How could that happen?
Simpler example: Imagine a billiard ball that has a trajectory that takes it into a time portal that goes back in time by a small portion of a second. However, before the ball makes it to the portal, it comes out (naturally, it went back) and knocks the original ball off it's trajectory so that it never hits the portal. This situation actually has a fairly logical conclusion (believe it or not). Suppose instead that the ball was headed towards the portal, but in such a way as to miss it. However, when the ball goes through the portal (hold on a sec...) it goes back and hits itself onto a trajectory that forces it into the portal (there it is!).
I know this example is confusing, so I provided these links to better explainations. The second link has a nice diagram demonstrating this. Credit must be given to Kip Thorne for coming up with this solution to the famous "Grandfather" paradox.
Anyone else have any thoughts on the idea of time travel and paradoxes? I am of the opinion that these paradoxes prevent time travel from occuring. Another popular belief if that time travel is possible, but only in the forward direction. Yet another belief is that when you travel through time, you actually enter a different "universe" from our own. This theory is directly tied in to the "multiverse" theory. Any other insight?
You're lucky, my VAIO only gets about 25 minutes.
The article didn't say that 10Gs the ONLY way that it detects a collision. It was simply an example of ONE of the ways.
I couldn't agree more. However, note that Mars is close to the asteroid belt. In fact, theory suggests that the moons of Mars are asteroids that were captured when they got too close. I think that suggests that Mars is more likely to be hit than other terrestrial planets. As likely as this article suggests? I don't know.
Um... check your facts. The atmospheric pressure on Mars (a direct effect of the density of the atmosphere) is approximately 1/100th of the pressure on Earth. So actually, Earth has a FAR thicker atmosphere.
I personally don't think this is any worse than ad agencies doing market research to determine which ads work and which ones won't. This is just taking it to the next level.
Don't get me wrong, I dislike advertisements as much as the next guy, but what differentiates me (and most of hte geek community) from the next guy is that fact that I know how to look at an ad and know when I should and should not listen to what's being said. When someone watching an ad is aware of the techniques used to create the ad, it's not very likely to work.
Example: The annoying beer commercials designed to associate their beer with having fun. I know that's what they are doing, so I know to ignore the commercial.
I seriously doubt any ad developed using this technique will be so effective as to hinder my ability to logically conclude whether or not the product being advertised is actually worth spending money on.
The Seattle Robotics Society has sumo competitions.
I have seen a few of these competitions in my area (Denver/Boulder, CO). All of the ones i have seen seem to follow the rules that the Seattle Robotics Society created.
but think about it, how many times have you screwed up a math problem? now how many times has you TI83? i'll take a robot's steady hand to a live doctor any day.
I would argue that a robot capable of performing heart surgery is slightly more complicated than a TI83. Let's all remember that the number of errors in a system typically goes up with the complexity.
*insert obligatory "It better be running Linux instead of Windows" joke, pointing out that it might crash and kill someone if it's running Windows*
It's good to see that such enthusiasm can be found for Linux in a 4th grade classroom. I think this is one of the areas that is commonly ignored by those of us trying to "spread the word."
My girlfriend's little brother is in 9th grade right now and every time he watches me use my computer, he is enthralled by Linux. I wonder if it's simply easier for younger people to be excited by Linux because they are more pliable. This is something that warrants exploration.
I have to disagree with this generalization. While I agree that many of the PCs in the school system are pretty much a waste of space and time, that doesn't mean they don't have a place.
At my high school (I graduated in '99), I took multiple classes about multimedia design and computer science. In fact, the Computer Science 1 class I took in high school gave me college credit which transferred easily to just about any major university in the state (Colorado).
At the same time however, there were 3 large computer labs at my high school and I recall being herded in there several times only to waste half of the class time learning completely useless software that barely demonstrated what we were supposed to learn. Given that, I think it's fair to say that computers in schools may be overhyped, but that doesn't mean they don't belong there.
I recently heard an interview with her co-host, Tyler Harcott. He was asked whether or not the junkyard is stocked and I believe he said that no parts are added to the junkyard, but an evalutation is made beforehand to determine if the challenge is possible. I get the impression that if a challenge is deemed impossible or too hard, then it is thrown out in favor of a better one.
I don't think so. I think it's pretty amazing that this could occur within Wine. I'd be VERY pleased if I were a Wine developer.