A polygraph is based on the assumption that someone who lies feels guilty about it, and thus nervous; this seems to be based on the assumption that a terrorist who's killing people in the name of Allah feels guilty about it.
No, this method is based on the fact that the human brain is a remarkable information processing device.
In information theory there's one fundamental parameter called entropy, which can be loosely described as the "degree of surprise" in the information.
This P300 brain wave seems to indicate the result of some calculation performed in the brain to measure the entropy in the information presented to the brain. To eliminate this response, by training, drugs, or any other method, would probably eliminate a fundamental step in the information processing the brain does.
People often seem to think of information theory like some sort of "human science", it's not. Information theory is very different from "information technology". Information theory is a mathematical science which has been very well tested in its basic principles. It was only by applying principles derived from information theory that our modern communication devices could be developed.
The human brain may use data processing mechanisms that we aren't aware of, but it would be very surprising if it could still work while violating basic mathematical principles like information theory. That would be like a machine that needs "2 + 2 = 5" to be true to function.
Red Hat has done more - 16 times as much, in fact - towards getting Linux on the desktop
That's assuming each line of code has the same value.
For me the important point is with which system can I get a computer working quicker and with less effort for installation and maintenance. Ubuntu wins.
OK, you may say that this only reflects the superiority of APT over RPM. Comparing Ubuntu with Debian, Ubuntu wins again.
you plot every xyz coordinate of every piece of matter in the universe. you will end up with a shape, no matter how odd it looks (donut, blob, square, pyramid, who cares). that shape has a center, which is the average of all xyz coordinates.
This would be true only if the universe had an euclidean geometry.
This is hard to visualize in three dimensions, so let's start with a two-dimensional case. Imagine a perfectly flat horizontal surface. Any triangle you draw in that surface will have three internal angles that add up to 180 degrees. If you draw any finite number of points there you could take the average of the xy coordinates and define a "center" for that set of points.
Now imagine a curved surface, let's say the surface of the earth. Define a triangle like this: point A is at zero latitude, zero longitude. Point B is at zero latitude, 90 degrees West longitude. Point C is at the North Pole. This triangle has three angles of ninety degrees, adding up to 270 degrees.
How would you define a "center" for a set of points randomly distributed over the surface of the earth? You could do it only if those points were sufficiently close together so the surface between them could be approximated by a flat surface. You can talk about the center of a continent, but the center of the whole surface of the earth is undefined.
Imagine the same problem in a universe with three dimensions that's curved in a fourth dimension and you will understand a bit of what general relativity is all about.
In the 20th century, which you remember so fondly, it was a woman's job to be a mother and housewife. It was she who stayed at home taking care of children and elders, while dad went to work.
Also, the gap between rich and poor was so wide that middle-class families earned enough to hire helpers from the lower classes. There was the cook, the housemaid(s), the gardener, to help take care of house and family.
At least as far as I understand it some methods of FTL would be non-paradoxical if there was actually a universal reference frame instead of everything being, well, relative.
This universal reference exists and is known by scientists, google for cosmic microwave dipole.
Our galaxy is moving at 627 km/s in relation to the microwave background radiation of the universe, which is the nearest direct effect of the Big Bang that we can observe.
The media industry makes so much noise about what they call "piracy" supposedly causing artists to starve, how can they allow this automation to happen?
After all, a live performance is much harder to "steal". The only way I can imagine of doing it would be drilling holes in the theater wall to let people watch from the outside without paying.
Automating musicians' jobs takes away one sure way they have to earn a living.
If you look at the photo in TFA you'll see that the wheel on the upper left side is sunk in sand up to the hub, and there's a sand mound behind it. That pretty much satisfies my definition of "stuck in the sand".
If that wheel were sitting on the surface instead of half buried in the sand, like the other wheel is, Spirit would clear that rock.
If I had to rate achievements in space exploration, the greatest would still be putting men on the moon.
First, because it was done in less than ten years after the project started.
Second, because it has never been repeated since 1972.
Third, because technology was more primitive. No carbon fiber and many other structural materials developed since then, very primitive computers.
And last but not least, because it came before the Mars landings. The technology developed for landing on the Moon was fundamental for a lot of that used for landing on Mars,
The Cold War was the main incentive to invest in the Space Race of the 1960s, so progress has slowed down almost to a crawl since then, but there's no denying that going to the Moon was an achievement rivaled by very few others in the history of technology.
And why would anybody spend 100$ on a calculator when you can almost get a laptop for that price today?
Hmmm, let's say you can get *half* a netbook for that price.
The answer why people buy calculators is simple: the keyboard. A full computer may be much more powerful, but there are people who just need to do calculations and there's nothing like a specialized keyboard to speed that up.
If the price were right (let's say about $20) I bet there would be a market for a USB calculator keyboard that you can connect to the computer.
Not everyone wants to learn the intricate details of how their OS works, some of them just want to use it.
What many people don't realize is that this is true for advanced users as well. I know the intricate details of Linux, but don't want to be bothered by them, so I choose to use Ubuntu.
It's the same thing with programming languages. I have programmed in C for over 25 years, but I use Python for many jobs. Having a simpler language to program makes my work more productive for day to day tasks, although I can resort to C whenever Python isn't powerful enough.
As I understood from the press release, the purpose of the test was to find a viable way to control the attitude of the sail itself. Being so thin, it would flutter and probably be ripped apart if handled roughly. An LCD is an interesting idea in this context, although I believe the LCD would be orders of magnitude thicker and heavier than the solar sail.
As for the momentum needed, it would be very small, because the disturbing momentum itself is very small. Since all the perturbation comes from radiation pressure, it's no big deal to get the correction from radiation pressure as well.
if this technology is a potential alternative to thrusters for bleeding the reaction wheels on future spacecraft.
I suppose that the idea is to make momentum dumping unnecessary. If the torque is always perfectly zero there will be no momentum accumulating on the wheels.
for most spacecraft fuel for attitude control is the limiting factor on mission duration
Not for geostationary satellites. For those, inclination control consumes about 90% of the fuel. Drift control depends on the longitude where the satellite is, but it typically consumes 90% of the rest, so attitude control consumes only a few percent at most of a geostationary satellite fuel budget.
There are already some commercial geostationary satellites that use solar radiation pressure for attitude control. Depending on the satellite model, this can be done either by setting each solar power panel at a slightly different angle or by having small auxiliary reflective panels that can be turned to the specific angle needed to apply the needed torque to the satellite.
Actually, the needed correction is small, because satellites are designed to be more or less symmetrical to begin with.
I wonder what amount of torque they were able to develop with this? It seems like it was pretty effective.
IAARS (I Am A Rocket Scientist). If there are no fluid leaks anywhere, as there shouldn't be in a properly functioning spacecraft, then *all* of the torque that changes the attitude of a spacecraft comes from solar radiation pressure alone. Therefore there should be not much problem in controlling attitude by modulating solar radiation pressure.
As a matter of fact, this effect is already being used today in commercial satellites. Some of them have adjustable panels that can be turned so that the solar radiation torque is zeroed. The new idea here isn't using solar radiation for attitude control but using LCD panels to modulate the radiation pressure.
The problem in understanding how such a small pressure as solar radiation can cause a spacecraft to rotate is that we are used to thinking about things here on the earth surface, where there are many other forces around us. In orbit, the spacecraft is in free fall in a vacuum, there's no friction and no wind, it will move to the slightest impulse applied. A typical commercial geostationary satellite may need attitude maneuvers a few times a week.
places where people have televisions also have public libraries
I'm Brazilian and you wouldn't believe how few public libraries there are in Brazil. Even most public schools don't have libraries. But every family, even the poorest ones, have a TV.
If the light is red and you drive past it, how can you in any way claim to be innocent?
If the man was alive and you killed him, how can you in any way claim to be innocent?
What you are saying is that if someone is murdered and the security cameras point at you a trial is not needed.
In the case that you were trying to say that running a red light is not as bad as murdering someone, therefore the standards of fairness should be set lower, then the US Constitution has something to say about that. The Sixth Amendment says you have a right to trial by jury in any criminal case. If it's a civil case the Seventh Amendment says there's a right to trial by jury whenever the value in controversy exceeds twenty dollars.
Don't like that? Change the Constitution, there's a well-defined procedure for doing it.
I wonder what medium we should use if we want to store data for a really, really long time
If I were rich enough, I would develop something like a CD made of stainless steel. There's a nickel-iron meteorite that lasted over 100 million years after falling on the earth surface. I believe that's the oldest object found where the original material is intact, not fossilized.
Nickel iron meteorites are a natural form of stainless steel. There are many different steel alloys called "stainless" with different corrosion resistance. My own choice for something that I wished to last forever would be Hastelloy B2 which is, AFAIK, the most corrosion-resistant non-precious metal alloy known.
no civilization has yet wanted to spend 500 years getting here
Have you wondered why our own civilization worries so much about "terrorism" these days?
It's not like our civilization wants to succumb to religious fanaticism. Only a few individuals belonging to one of the many religions present in our civilization believe in ritual self-immolation. However this suicide bomber meme has come to dominate the media.
Now, imagine a civilization a hundred years or so more advanced than ours. Surely, not many people will want to invest five hundred years to go to a neighboring star system. But it takes only one fanatic to dominate the media as, unfortunately, we learned in 2001-09-11.
I think that if we survive and evolve as a civilization a hundred years more we will, inevitably, reach the stars.
Human nature can work for both good and evil. There will be billions who sit at home and watch TV but a few people will not be satisfied until they visit every star system in the galaxy.
Reach in, grab firmly, give one pump and two shakes, let go.
I tried that but none of the women in my life found it to be particularly satisfying;)
Hmmm, let's see. A "handshake" involves hands on both sides of the equation. Simplifying, you can eliminate the hands on both sides. Have you tried just pumping and shaking her?
Slashdot Mirror
No, this method is based on the fact that the human brain is a remarkable information processing device.
In information theory there's one fundamental parameter called entropy, which can be loosely described as the "degree of surprise" in the information.
This P300 brain wave seems to indicate the result of some calculation performed in the brain to measure the entropy in the information presented to the brain. To eliminate this response, by training, drugs, or any other method, would probably eliminate a fundamental step in the information processing the brain does.
People often seem to think of information theory like some sort of "human science", it's not. Information theory is very different from "information technology". Information theory is a mathematical science which has been very well tested in its basic principles. It was only by applying principles derived from information theory that our modern communication devices could be developed.
The human brain may use data processing mechanisms that we aren't aware of, but it would be very surprising if it could still work while violating basic mathematical principles like information theory. That would be like a machine that needs "2 + 2 = 5" to be true to function.
That's assuming each line of code has the same value.
For me the important point is with which system can I get a computer working quicker and with less effort for installation and maintenance. Ubuntu wins.
OK, you may say that this only reflects the superiority of APT over RPM. Comparing Ubuntu with Debian, Ubuntu wins again.
This would be true only if the universe had an euclidean geometry.
This is hard to visualize in three dimensions, so let's start with a two-dimensional case. Imagine a perfectly flat horizontal surface. Any triangle you draw in that surface will have three internal angles that add up to 180 degrees. If you draw any finite number of points there you could take the average of the xy coordinates and define a "center" for that set of points.
Now imagine a curved surface, let's say the surface of the earth. Define a triangle like this: point A is at zero latitude, zero longitude. Point B is at zero latitude, 90 degrees West longitude. Point C is at the North Pole. This triangle has three angles of ninety degrees, adding up to 270 degrees.
How would you define a "center" for a set of points randomly distributed over the surface of the earth? You could do it only if those points were sufficiently close together so the surface between them could be approximated by a flat surface. You can talk about the center of a continent, but the center of the whole surface of the earth is undefined.
Imagine the same problem in a universe with three dimensions that's curved in a fourth dimension and you will understand a bit of what general relativity is all about.
Such as democracy and human rights?
In the 20th century, which you remember so fondly, it was a woman's job to be a mother and housewife. It was she who stayed at home taking care of children and elders, while dad went to work.
Also, the gap between rich and poor was so wide that middle-class families earned enough to hire helpers from the lower classes. There was the cook, the housemaid(s), the gardener, to help take care of house and family.
In case you don't know, there are people who have to work for a living and can't stay home all day taking care of their parents.
This universal reference exists and is known by scientists, google for cosmic microwave dipole.
Our galaxy is moving at 627 km/s in relation to the microwave background radiation of the universe, which is the nearest direct effect of the Big Bang that we can observe.
If you play a recording you have to pay to the recording copyright's owner.
If you play from the original score you have to pay to the score copyright's owner.
Perhaps the second means a lower cost than the first.
The media industry makes so much noise about what they call "piracy" supposedly causing artists to starve, how can they allow this automation to happen?
After all, a live performance is much harder to "steal". The only way I can imagine of doing it would be drilling holes in the theater wall to let people watch from the outside without paying.
Automating musicians' jobs takes away one sure way they have to earn a living.
If you look at the photo in TFA you'll see that the wheel on the upper left side is sunk in sand up to the hub, and there's a sand mound behind it. That pretty much satisfies my definition of "stuck in the sand".
If that wheel were sitting on the surface instead of half buried in the sand, like the other wheel is, Spirit would clear that rock.
If I had to rate achievements in space exploration, the greatest would still be putting men on the moon.
First, because it was done in less than ten years after the project started.
Second, because it has never been repeated since 1972.
Third, because technology was more primitive. No carbon fiber and many other structural materials developed since then, very primitive computers.
And last but not least, because it came before the Mars landings. The technology developed for landing on the Moon was fundamental for a lot of that used for landing on Mars,
The Cold War was the main incentive to invest in the Space Race of the 1960s, so progress has slowed down almost to a crawl since then, but there's no denying that going to the Moon was an achievement rivaled by very few others in the history of technology.
Hmmm, let's say you can get *half* a netbook for that price.
The answer why people buy calculators is simple: the keyboard. A full computer may be much more powerful, but there are people who just need to do calculations and there's nothing like a specialized keyboard to speed that up.
If the price were right (let's say about $20) I bet there would be a market for a USB calculator keyboard that you can connect to the computer.
What many people don't realize is that this is true for advanced users as well. I know the intricate details of Linux, but don't want to be bothered by them, so I choose to use Ubuntu.
It's the same thing with programming languages. I have programmed in C for over 25 years, but I use Python for many jobs. Having a simpler language to program makes my work more productive for day to day tasks, although I can resort to C whenever Python isn't powerful enough.
As I understood from the press release, the purpose of the test was to find a viable way to control the attitude of the sail itself. Being so thin, it would flutter and probably be ripped apart if handled roughly. An LCD is an interesting idea in this context, although I believe the LCD would be orders of magnitude thicker and heavier than the solar sail.
As for the momentum needed, it would be very small, because the disturbing momentum itself is very small. Since all the perturbation comes from radiation pressure, it's no big deal to get the correction from radiation pressure as well.
I suppose that the idea is to make momentum dumping unnecessary. If the torque is always perfectly zero there will be no momentum accumulating on the wheels.
Not for geostationary satellites. For those, inclination control consumes about 90% of the fuel. Drift control depends on the longitude where the satellite is, but it typically consumes 90% of the rest, so attitude control consumes only a few percent at most of a geostationary satellite fuel budget.
There are already some commercial geostationary satellites that use solar radiation pressure for attitude control. Depending on the satellite model, this can be done either by setting each solar power panel at a slightly different angle or by having small auxiliary reflective panels that can be turned to the specific angle needed to apply the needed torque to the satellite.
Actually, the needed correction is small, because satellites are designed to be more or less symmetrical to begin with.
IAARS (I Am A Rocket Scientist). If there are no fluid leaks anywhere, as there shouldn't be in a properly functioning spacecraft, then *all* of the torque that changes the attitude of a spacecraft comes from solar radiation pressure alone. Therefore there should be not much problem in controlling attitude by modulating solar radiation pressure.
As a matter of fact, this effect is already being used today in commercial satellites. Some of them have adjustable panels that can be turned so that the solar radiation torque is zeroed. The new idea here isn't using solar radiation for attitude control but using LCD panels to modulate the radiation pressure.
The problem in understanding how such a small pressure as solar radiation can cause a spacecraft to rotate is that we are used to thinking about things here on the earth surface, where there are many other forces around us. In orbit, the spacecraft is in free fall in a vacuum, there's no friction and no wind, it will move to the slightest impulse applied. A typical commercial geostationary satellite may need attitude maneuvers a few times a week.
I'm Brazilian and you wouldn't believe how few public libraries there are in Brazil. Even most public schools don't have libraries. But every family, even the poorest ones, have a TV.
In other words, which part of ALL they didn't understand? Was it the "A" or one of the two indistinguishable "L"?
I agree with that, as long as the fine (and the probability of getting caught) is the same for jaywalkers as for rolling stops.
If the man was alive and you killed him, how can you in any way claim to be innocent?
What you are saying is that if someone is murdered and the security cameras point at you a trial is not needed.
In the case that you were trying to say that running a red light is not as bad as murdering someone, therefore the standards of fairness should be set lower, then the US Constitution has something to say about that. The Sixth Amendment says you have a right to trial by jury in any criminal case. If it's a civil case the Seventh Amendment says there's a right to trial by jury whenever the value in controversy exceeds twenty dollars.
Don't like that? Change the Constitution, there's a well-defined procedure for doing it.
If I were rich enough, I would develop something like a CD made of stainless steel. There's a nickel-iron meteorite that lasted over 100 million years after falling on the earth surface. I believe that's the oldest object found where the original material is intact, not fossilized.
Nickel iron meteorites are a natural form of stainless steel. There are many different steel alloys called "stainless" with different corrosion resistance. My own choice for something that I wished to last forever would be Hastelloy B2 which is, AFAIK, the most corrosion-resistant non-precious metal alloy known.
Have you wondered why our own civilization worries so much about "terrorism" these days?
It's not like our civilization wants to succumb to religious fanaticism. Only a few individuals belonging to one of the many religions present in our civilization believe in ritual self-immolation. However this suicide bomber meme has come to dominate the media.
Now, imagine a civilization a hundred years or so more advanced than ours. Surely, not many people will want to invest five hundred years to go to a neighboring star system. But it takes only one fanatic to dominate the media as, unfortunately, we learned in 2001-09-11.
I think that if we survive and evolve as a civilization a hundred years more we will, inevitably, reach the stars.
Human nature can work for both good and evil. There will be billions who sit at home and watch TV but a few people will not be satisfied until they visit every star system in the galaxy.
Hmmm, let's see. A "handshake" involves hands on both sides of the equation. Simplifying, you can eliminate the hands on both sides. Have you tried just pumping and shaking her?
Let me see, the pirate version of a submarine game is one where you are sent to the Somalia coast to capture the pirates there?