Standard double-slit intro into quantum weirdness. You could just link to the Dr. Quantum video.
LOL...standard quantum weirdness...as if its commonality makes it any less shocking and germane to the discussion. There is a reason why most quantum courses begin with this...because it is accessible and clear, yet underlines the implications of Schroedinger's equation beautifully.
For those of you who hear that quantum mechanics is strange, but aren't sure exactly why, here is a little primer, based on the opening lecture from my intro quantum course:
Pass a a beam of electrons through two closely spaced gaps. If the electrons were like bullets, one would expect to detect two bright spots on the detecting screen directly opposite the holes. This is not what you will observe however. Instead you will see on the detector a single location midway between the two holes with many electron strikes. The locations opposite the holes receive few electron strikes, but continuing outward there will be locations with lots of electron strikes followed by locations with few electron strikes. How can we explain this?
Well the bright and dark patterns are consistent with wave diffraction and interference. We see similar interference patterns with light, and with other types of waves. So the electrons have wavelike properties. Are multiple electrons "interfering" with each other? Well, if you reduce the beam intensity so that only single electrons are passing through the slits, perhaps only one every few seconds, then the same pattern of diffraction and interference occurs! So, that seems to imply that single electrons are passing through both slits and once, and then interfering with themselves! I thought single electrons were particles!??? !
Now install a device or mechanism that measures which slit electrons pass through and indicates the results to you. What do you observe now? The electrons will now behave like bullets, dutifully going straight through one hole or the other and striking the detector screen directly opposite the holes. No diffraction. No interference, or at least not enough to speak of. Experiments like this led Bohr to exclaim that "those who are not shocked when they first see quantum mechanics cannot possibly have understood it."
One interpretation of this is that if you don't know which hole the electron goes through, then it goes through both holes at once. If you don't know what spin an electron has, then it has both spin up and spin down. At the small scale, probability seems to be everything. If there is a 40% chance that an electron is at location A, and a 60% chance that the same electron is at location B, then 40% of it is located at A, and 60% of it is at B. It seems your lack of knowledge about the electron can cause it to be "smeared" over multiple locations. This smearing is related to the wavelike properties. As soon as you pin down the location of the electron, then it is no longer in two places at once. It is a definite particle.
Consciousness seems to play a role in this, as it seems our measurement of either the momentum or the position of an electron seems to fundamentally change its properties. It seems that our knowledge of the particle changes the particle. I understand this is difficult to accept. But any alternative explanation must take into account the strange results from experiments such as the one described above. I am not sure where the logical fallacy would lie here.
For a very well put together documentary on the irrational nature of economic value, watch this Nova episode, "Mind Over Money". (sorry, US only...otherwise try bittorrent)
One of the funniest moments in the documentary occurs when otherwise intelligent economics students are caused to pay $28 for a twenty dollar bill. The experiment works by causing the losing bidder to forfeit his bid, not unlike the way real markets behave. The dominant economic models today assume that the consumer will rationally act to maximize his wealth (or act as if he is). Clearly the existence of bubbles such as the recent real estate bubble contradict this.
I asked an MBA friend about how someone could pay $28 for a twenty dollar bill. His response was that value was what was defined by the consumer, and that maybe that twenty dollar bill was actually worth $28 to the buyer. However there are some very deep flaws in this argument. If we assume that the price a consumer pays is ALWAYS the right price by definition, then the consumer can never be wrong. When Dutch people in the 1600's bought single tulip bulbs for the price of a house, those prices were rational under this assumption. Assuming that the price a consumer pays is always correct puts the assumption of market rationality beyond falsification. This is textbook circular reasoning. No wonder economics has often been called "the Dismal Science".
On their aircraft the throttle is to set the desired thrust, a bit like setting cruse control in your car to a given speed which it then tries to match. Even on a Boeing aircraft the pilot should never use the position of the sticks to indicate thrust levels because if an engine is failing it might not be producing the requested amount. Therefore on both aircraft the readout of actual measured levels is the only reliable indication.
Perhaps I wasn't specific enough in my comments. The way I understood it from the documentary, on an Airbus, a pilot's movement of the engine control lever sends a signal to the computer to increase or decrease the power. When the autopilot on an Airbus modifies the power setting, the physical control levers do not give an indication of the change (or the attempted change). On a Boeing, an autopilot change is reflected in a physical movement of the control lever. I agree with you that a pilot should not use the absolute position of the control lever as the most reliable source of engine power output data. However, the Boeing's physical lever movement is a powerful visual cue that the computer has at least attempted to change the engine power, and is a reminder to look at the engine output gauges on the screen. In a stressful situation where multiple indications and warnings are blaring in the cockpit, that physical reminder (or lack thereof) may have been an important factor in this accident.
One witness claimed he saw the aircraft fly down sparkling in pieces and fire.
I am unaware of witnesses to this particular crash. It was in the middle of the Atlantic. If there were direct witnesses, why did it take so long to find the wreckage?
The whole situation is bad and I wonder why the pilots didn't fly around these storms?
The Nova documentary speculated that a smaller storm in their immediate path blocked the radar signals from a larger storm behind it. By the time they realized there was a large ring of storm cells around them, they could not escape. They have radar records of that night, which can be combined with the known flight path. The above hypothesis is reasonable given the data.
Likely as not, nothing will jump out, especially if, say, the autopilot is flying the
aircraft using faulty input, e.g., input from an ice-covered sensor. That is likely
to cause other sensors to show perverse readings that may (or may not) be very
subtle, and may have multiple or ambiguous causes.
Perhaps, but what will be very interesting is the data on the power settings on the airplane, especially in regard to (a) the autopilot reducing power to 70% in anticipation of passing through a thunderstorm and (b) the pilot's changing of that setting to a more appropriate level. The key question is whether or not the autopilot lowered the power before kicking off due to bad airspeed data, and whether or not (and when!) the pilots realized that the power was lower and what they did in response. That goes to the heart of the speculated cause of this crash, according to the Nova episode on the subject.
the pilots should still be able to bring the aircraft to area where visual flight rule is possible.
The pilots should be able to fly the plane without airspeed data, according to the Nova documentary. They just set the engine to a particular level and maintain a particular angle of attack. The Nova documentary speculated that due to a variety of factors and distractions that the pilots were unaware of the actual power settings of the airplane. Apparently the airspeed/angle of attack window is quite narrow at that altitude, and if the plane deviates from that window, the airplane may become uncontrollable. It may have taken a brief oversight of the power settings to bring down the plane. Sort of pilot error, perhaps. But there were definitely mitigating factors.
From the telemetry data that I've hear of from the PBS Nova documentary, it seems highly likely that the pitots failed nearly simultaneously, robbing the pilots of airspeed data. Even if they can argue that the pilots could have saved the plane, those pitots should never have failed/froze. There is blame to go around I think.
This was a very interesting documentary. I was particularly interested in the inferences about the user interface approach of Airbus versus Boeing. In short, Airbus planes are controlled with joysticks that translate pilot intentions into actual executable commands to the control surfaces. If the pilot tells the computer to do something stupid, the computer won't do it. Contrast this with Boeing, where the pilots control the plane with a proper control stick that gives more effective feedback to the pilots. In a Boeing airplane, when the computer lowers engine power on autopilot, the engine control lever actually moves in a very visible way. However, on Airbus planes, the levers DO NOT move. The only indication to a pilot that the power has dropped is a small circular readout on a computer screen. The Nova scientists theorized that the pilots didn't realize that the computer had lowered power in anticipation of flying through a thunderstorm, or at least that they realized it too late. They theorize that for about a minute the pilots were flying the plane as if the engines were on high power, when they were actually on a much lower power setting. This, combined with a lack of reliable airspeed data may have caused the pilots to put the plane in an unrecoverable mode of flight. Or maybe it was different. We will know soon enough.
BTW, for those of you outside the US, the above video link won't work. I think the video is on bittorrent somewhere. It is definitely worth watching if you haven't seen it.
Pirates are not new. And through the history of piracy, it has been shown time and time again that to rid the oceans of piracy, the conditions on land that led to the piracy in the first place must be changed. In the case of Somalia, we have a failed state with no real government. Poverty and lawlessness have led to the problem in the oceans off Somalia. Any ocean based solutions to this problem will be merely band-aides. As long as Somalia remains as it is, the piracy problem will continue, battleships and computer games not withstanding.
*Now*, after we shot their Afghan allies and blew things up inside Pakistan, they care about us enough to be a threat. But in 2000, they only threatened to (sic) their neighbors.
That is a gross oversimplification. First off, it IS in our interests to prevent nuclear war between Pakistan and India. Setting the precedent of a modern nuclear shooting war would be very dangerous to world stability. Secondly, you seem to ignore the complex nature of the Pakistani government and power structure. If Afghanistan was to again come under the sway of the Taliban, it would help to give those "scary elements" of the Pakistani power structure more power and influence. There are moderates in Pakistan, but they have a tenuous grasp on power. If the balance tips too far towards extremists, the results could be dangerous. Do you really want a fundamentalist government in charge of nuclear weapons? They could send one of those weapons in a cargo ship to an American city very easily. If they are sufficiently fundamentalist and irrational, then the usual calculus of deterrents will not occur to them.
The success of the Iraq mission is an open question...we will not know for a few decades.
It has already been acknowledged as a failure. The purpose of the Iraq mission was to establish a counter-balance to Iran. That has not happened. It is doubtful that it will ever happen.
Yes, perhaps. But there is no despot in power now. My initial worries about the Iraq war still apply. Iraq was set up with a Sunni minority in power over a Shiite majority. I suppose it was implicit in this arrangement that that minority would exert a forceful influence on the majority it ruled. The risk of shattering this system was civil war from the tensions built up under the old regime. Still, Saddam was truly a despot. Where Iraq goes from here is I believe still up in the air. They have experienced the forceful hand of a dictator and the chaotic results of his absence. They likely understand now the need for a strong government to bring order and stability.
You make the (very terse) argument that "the purpose of the Iraq mission was to counter-balance Iran". Bringing a form of democracy to a society where the majority is Shiite would seem likely to bring the Shiite factions more power. Since Iranians are also mainly Shiite, this would seem to be counterproductive in limiting the power of Iran, so you do have a point. Still, I don't think the matter is anywhere near as simple as this. It remains to be seen what will happen in Iran in the next twenty to thirty years, let alone what happens in Iraq. Younger Iranians are different from their parents, and will probably not put up with the religious tyranny that they live under now. Which is why I think we will not understand the full implications of the Iraqi invasion for a long time.
Still, I believe this was all a very reckless gamble on the part of the Bush administration. They didn't really seem to comprehend the forces that they were unleashing. They seemed to have the cult-like expectation that free markets would unleash a wave of prosperity and peace. One can see this from the fact that they devoted so few troops to the endeavor, and seemed to have done almost no planning as to how to "keep the peace" after the dust settled. In some sense even worse were their fallacious justifications for going to war; they were almost comedically false. They say the first casualty of war is truth, but this war went much farther I believe than past wars. Seeing American troops vainly searching for mobile chemical weapons factories brings to mind images of a malevolent Don Quixote.
So why did we invade and occupy Iraq and Afghanistan?
The success of the Iraq mission is an open question...we will not know for a few decades. Certainly it was very poorly executed, with a shortage of necessary troops that resulted in many years of chaos. As to the Afghan situation, it is obvious why we are there. Pakistan has nuclear weapons. That is it. Period. Let me explain:
Pakistan has a very strange government and political situation. There are forces that tend to be very anti-western and tend to a more fundamentalist religious bent. And there are forces that are more pro-western, Benazir Bhutto being a prime example. Their intelligence services have some strong anti-western members. Pakistan walks a tightrope, being pulled both ways by these forces. AND THEY HAVE NUCLEAR WEAPONS. The fear, probably justified, is that if the Afghan government falls, and the Taliban comes in to fill the power vacuum, this will strengthen the anti-western forces in Pakistan, possibly resulting in a fundamentalist anti-western government with access to nuclear weapons. Since fundamentalists tend to view the world in more absolutist black and white terms, it would seem more likely that they would actually use their nuclear weapons, either against nuclear armed India, or against American targets.
You can debate about the strength of the above argument, but I think it is reasonably certain that this is the type of thinking that is keeping us in Afghanistan.
I believe that OpenStep and/or its progeny are integrated into OSX and iOS, which is one of the reasons that Apple can swap around it OS's onto various CPU designs so easily. Think of the transition from PowerPC to Intel, or the other chips that run the iPhone/iPod Touch/iPad. This is a huge competitive strength, and is likely a key reason for the success of Apple.
I always was very hesitant to provide Sony with my credit card. I simply don't trust them. I hate the way the PS3 always tries to dump you into the Playstation Store. It just feels obnoxious and disrespectful. And now hearing about their technical negligence, I am even more happy with my decision. Honestly, I have never had any need or desire to buy anything on PSN.
I have replaced most of the light bulbs in my house with CFL's. Here is my experience:
Firstly, buy the good ones. I use Phillips. The open coil kind, and not the ones that come already surrounded by a glass dome. The glass dome ones have an irritatingly long warm up time. The good ones are the ones where you can touch the coil directly.
The bulbs that I use have a fairly good color. I have used the cheap ones, and their color was awful, reminiscent of the lighting at a typical swimming pool. The Phillips bulbs have a color that is nearly indistinguishable from regular bulbs. And they come on almost instantly, and are at full brightness almost right away. The only incandescent bulbs I use are in my nighttime dimmed reading lights. I like the nice warm orange glow of a dimmed 40W incandescent bulb just before bed. Other than that they do work great. They DO work in washrooms. They DO work inside light enclosures. And you won't really notice the difference, except on your power bill.
What would happen to the Earth if the sun suddenly disappeared?
Under Einstein's Theory of Relativity, nothing can travel faster than light. If the Earth "disappeared", or some reasonable facsimile, it would take 7 - 8 minutes before we stopped receiving sunlight, since that is the time for light to travel from the Sun to the Earth. The Sun's gravity is what keeps pulling the Earth in a circular path...without it the Earth would travel in a fairly "straight line". If the Sun suddenly disappeared, its gravitational influence would also disappear. But Einstein's theory implies that nothing can travel faster than light, so the gravitational change caused by the Sun's disappearance cannot reach us sooner than 8 minutes, since otherwise this would imply that the gravity disturbance could exceed the speed of light.
Einstein's General Relativity implies that objects with mass cause distortions in space. It is these distortions that we experience as gravity. The distortions are rather difficult to visualize, however. To really see them in your mind, you have to be able to think in four spacial dimensions. The typical way of making spacial distortion easier to visualize is to reduce space to 2 dimensions. Then you can imagine that space is like a flat rubber sheet. Place a ball on the sheet, and it creates a distortion, as the ball pushes the rubber sheet down. The rubber sheet is still 2 dimensional, but to see the distortion we need to step back and look at it from our 3rd spacial dimension. Now extend space to 3 dimensions. Objects with mass have a similar distortional effect on 3 dimensional space, but to see the distortion, we have to step into the 4th spacial dimension.
If the Sun did disappear, the change in the spacial warping would radiate outwards from the former location of the Sun at the speed of light, kind of like a wave on a pond through 2 dimensional space, though actually in 3 dimensions, with the distortion really only "visualizable" by looking at space from a fourth dimension. It's tricky stuff...General Relativity, which is really Einstein's theory of gravity, is usually only studied seriously in grad school physics.
It is only a small part of the article. Without graphs, and without without references. To anyone seeking to use this for academic purposes it would be largely useless. Still...
Here are a few paragraphs of the original article:
Spectroscopy is a method typically used to assess an unknown quantity of energy by means of a frequency measurement. In many problems, resonance techniques1, 2 enable high-precision measurements, but the observables have generally been restricted to electromagnetic interactions. Here we report the application of resonance spectroscopy to gravity. In contrast to previous resonance methods, the quantum mechanical transition is driven by an oscillating field that does not directly couple an electromagnetic charge or moment to an electromagnetic field. Instead, we observe transitions between gravitational quantum states when the wave packet of an ultra-cold neutron couples to the modulation of a hard surface as the driving force. The experiments have the potential to test the equivalence principle3 and Newton’s gravity law at the micrometre scale
Generally, a quantum mechanical system that is described by two states can be understood in analogy to a spin-1/2 system, where the time development is described by the Bloch equations, assuming two states of a fictitious spin in the multiplet, similar to spin-up and spin-down states. In magnetic resonance of a standard spin-1/2 system, the energy splitting results in the precession of the related magnetic moment in the magnetic field. Transitions between the two states are driven by a transverse magnetic radio frequency field. Similar concepts can be applied to any driven two-level system, for example in optical transitions with light fields. Variations are inherently connected to high-precision measurements such as atomic clocks6, atom interferometry7, nuclear magnetic resonance8, quantum metrology9 and the related spin-echo technique10. The sensitivity reached so far11 in the search for the electric dipole moment of the neutron is 6.8×1022eV, or one Bohr rotation every six days.
In this Letter, we demonstrate that energy eigenstates in the gravity potential of the earth can be probed using a new resonance-spectroscopy technique, using neutrons bounced off a horizontal mirror. This spectroscopy technique has in common the property that a quantum-system is coupled to an external resonator. Quantum mechanical transitions with a characteristic energy exchange between the coupling and the energy-levels are observed on resonance. A novelty of this work is the fact that the quantum mechanical transition is driven by an oscillating field that does not directly couple an electromagnetic charge or moment to an electromagnetic field. Instead, we observe energy transfer on resonance that is based on gravity-quantum states coupled to a modulator. We have named this technique gravity resonance spectroscopy, because the energy difference between these states has a one-to-one correspondence to the frequency of the modulator, in analogy to the nuclear magnetic resonance technique, where the energy splitting of a magnetic moment in an outer magnetic field is related to the frequency of a radio-frequency field. This is possible because of the feature of the quantum bouncing ball12, 13 that the levels are not equidistant in energy. The linear gravity potential leads to measured14, 15, 16 discrete non-equidistant energy eigenstates |nright fence. A combination of any two states can therefore be treated as a two-level system, as each transition can be addressed by its unique energy splitting or, in our case, by vibrating the mirror mechanically at the appropriate frequency. It has also been proposed to realize transitions between gravitational quantum states by means of oscillating magnetic gradient fields17. The physics behind these transitions is related to earlier studies of energy transfer where matter waves bounce off a vibrating mirror18, 19 or a time-dependent crystal20, 21. In the latter case the transitions are between continuum states, in the quantum bouncer the transitions are between discrete eigenstates. Optical dipole traps of atoms are reviewed in ref. 22.
Wow, my physics courses apparently forgot to mention that Newton's Law of Gravity had anything to say about the quantum states of neutrons. In fact, I was taught it's not a law; it's a falsified hypothesis.
Newton's Law of Gravity can be seen as an approximation of Einstein's theory. We have to be careful when we speak of "falsified". We haven't discovered that gravity is proportional to 1/r, or that gravity isn't attractive but repulsive. We have discovered that Einstein's models are better predictors of experimental results. We can still us Newton's models to send humans to the Moon. But Newton's model makes no sense when asking questions such as "what would happen to the Earth if the Sun suddenly disappeared. It doesn't predict the bending of light, nor does it properly describe certain orbital phenomenon.
Reader NotSanguine points out another study which challenges the idea that the brain is more important to the structure of language than cultural evolution.
Perhaps we should not forget the evolution of the structure of our tongue, mouth, and vocal chords in the evolution of language.
Trains are infinitely more comfortable than any other form of transportation, high speed or not. You can get up and walk around, go to the restaurant car, and stretch your legs out in widely spaced seats. The motion of the train is gentle and relaxing, and the view out of the train is often beautiful.
Trains are sometimes perceived as being more expensive than cars, but that is largely because the government maintains the roads "for free", while train companies have to maintain the tracks and pay for it using fare revenue. It makes me angry that our society has chosen to let our passenger railway infrastructure to decay. Passenger rail is vital to our national interest, especially in this world of rising fuel prices.
Slashdot Mirror
Standard double-slit intro into quantum weirdness. You could just link to the Dr. Quantum video.
LOL...standard quantum weirdness...as if its commonality makes it any less shocking and germane to the discussion. There is a reason why most quantum courses begin with this...because it is accessible and clear, yet underlines the implications of Schroedinger's equation beautifully.
For those of you who hear that quantum mechanics is strange, but aren't sure exactly why, here is a little primer, based on the opening lecture from my intro quantum course:
Pass a a beam of electrons through two closely spaced gaps. If the electrons were like bullets, one would expect to detect two bright spots on the detecting screen directly opposite the holes. This is not what you will observe however. Instead you will see on the detector a single location midway between the two holes with many electron strikes. The locations opposite the holes receive few electron strikes, but continuing outward there will be locations with lots of electron strikes followed by locations with few electron strikes. How can we explain this?
Well the bright and dark patterns are consistent with wave diffraction and interference. We see similar interference patterns with light, and with other types of waves. So the electrons have wavelike properties. Are multiple electrons "interfering" with each other? Well, if you reduce the beam intensity so that only single electrons are passing through the slits, perhaps only one every few seconds, then the same pattern of diffraction and interference occurs! So, that seems to imply that single electrons are passing through both slits and once, and then interfering with themselves! I thought single electrons were particles!??? !
Now install a device or mechanism that measures which slit electrons pass through and indicates the results to you. What do you observe now? The electrons will now behave like bullets, dutifully going straight through one hole or the other and striking the detector screen directly opposite the holes. No diffraction. No interference, or at least not enough to speak of. Experiments like this led Bohr to exclaim that "those who are not shocked when they first see quantum mechanics cannot possibly have understood it."
One interpretation of this is that if you don't know which hole the electron goes through, then it goes through both holes at once. If you don't know what spin an electron has, then it has both spin up and spin down. At the small scale, probability seems to be everything. If there is a 40% chance that an electron is at location A, and a 60% chance that the same electron is at location B, then 40% of it is located at A, and 60% of it is at B. It seems your lack of knowledge about the electron can cause it to be "smeared" over multiple locations. This smearing is related to the wavelike properties. As soon as you pin down the location of the electron, then it is no longer in two places at once. It is a definite particle.
Consciousness seems to play a role in this, as it seems our measurement of either the momentum or the position of an electron seems to fundamentally change its properties. It seems that our knowledge of the particle changes the particle. I understand this is difficult to accept. But any alternative explanation must take into account the strange results from experiments such as the one described above. I am not sure where the logical fallacy would lie here.
For a very well put together documentary on the irrational nature of economic value, watch this Nova episode, "Mind Over Money". (sorry, US only...otherwise try bittorrent)
One of the funniest moments in the documentary occurs when otherwise intelligent economics students are caused to pay $28 for a twenty dollar bill. The experiment works by causing the losing bidder to forfeit his bid, not unlike the way real markets behave. The dominant economic models today assume that the consumer will rationally act to maximize his wealth (or act as if he is). Clearly the existence of bubbles such as the recent real estate bubble contradict this.
I asked an MBA friend about how someone could pay $28 for a twenty dollar bill. His response was that value was what was defined by the consumer, and that maybe that twenty dollar bill was actually worth $28 to the buyer. However there are some very deep flaws in this argument. If we assume that the price a consumer pays is ALWAYS the right price by definition, then the consumer can never be wrong. When Dutch people in the 1600's bought single tulip bulbs for the price of a house, those prices were rational under this assumption. Assuming that the price a consumer pays is always correct puts the assumption of market rationality beyond falsification. This is textbook circular reasoning. No wonder economics has often been called "the Dismal Science".
On their aircraft the throttle is to set the desired thrust, a bit like setting cruse control in your car to a given speed which it then tries to match. Even on a Boeing aircraft the pilot should never use the position of the sticks to indicate thrust levels because if an engine is failing it might not be producing the requested amount. Therefore on both aircraft the readout of actual measured levels is the only reliable indication.
Perhaps I wasn't specific enough in my comments. The way I understood it from the documentary, on an Airbus, a pilot's movement of the engine control lever sends a signal to the computer to increase or decrease the power. When the autopilot on an Airbus modifies the power setting, the physical control levers do not give an indication of the change (or the attempted change). On a Boeing, an autopilot change is reflected in a physical movement of the control lever. I agree with you that a pilot should not use the absolute position of the control lever as the most reliable source of engine power output data. However, the Boeing's physical lever movement is a powerful visual cue that the computer has at least attempted to change the engine power, and is a reminder to look at the engine output gauges on the screen. In a stressful situation where multiple indications and warnings are blaring in the cockpit, that physical reminder (or lack thereof) may have been an important factor in this accident.
One witness claimed he saw the aircraft fly down sparkling in pieces and fire.
I am unaware of witnesses to this particular crash. It was in the middle of the Atlantic. If there were direct witnesses, why did it take so long to find the wreckage?
The whole situation is bad and I wonder why the pilots didn't fly around these storms?
The Nova documentary speculated that a smaller storm in their immediate path blocked the radar signals from a larger storm behind it. By the time they realized there was a large ring of storm cells around them, they could not escape. They have radar records of that night, which can be combined with the known flight path. The above hypothesis is reasonable given the data.
Likely as not, nothing will jump out, especially if, say, the autopilot is flying the aircraft using faulty input, e.g., input from an ice-covered sensor. That is likely to cause other sensors to show perverse readings that may (or may not) be very subtle, and may have multiple or ambiguous causes.
Perhaps, but what will be very interesting is the data on the power settings on the airplane, especially in regard to (a) the autopilot reducing power to 70% in anticipation of passing through a thunderstorm and (b) the pilot's changing of that setting to a more appropriate level. The key question is whether or not the autopilot lowered the power before kicking off due to bad airspeed data, and whether or not (and when!) the pilots realized that the power was lower and what they did in response. That goes to the heart of the speculated cause of this crash, according to the Nova episode on the subject.
the pilots should still be able to bring the aircraft to area where visual flight rule is possible.
The pilots should be able to fly the plane without airspeed data, according to the Nova documentary. They just set the engine to a particular level and maintain a particular angle of attack. The Nova documentary speculated that due to a variety of factors and distractions that the pilots were unaware of the actual power settings of the airplane. Apparently the airspeed/angle of attack window is quite narrow at that altitude, and if the plane deviates from that window, the airplane may become uncontrollable. It may have taken a brief oversight of the power settings to bring down the plane. Sort of pilot error, perhaps. But there were definitely mitigating factors.
From the telemetry data that I've hear of from the PBS Nova documentary, it seems highly likely that the pitots failed nearly simultaneously, robbing the pilots of airspeed data. Even if they can argue that the pilots could have saved the plane, those pitots should never have failed/froze. There is blame to go around I think.
This was a very interesting documentary. I was particularly interested in the inferences about the user interface approach of Airbus versus Boeing. In short, Airbus planes are controlled with joysticks that translate pilot intentions into actual executable commands to the control surfaces. If the pilot tells the computer to do something stupid, the computer won't do it. Contrast this with Boeing, where the pilots control the plane with a proper control stick that gives more effective feedback to the pilots. In a Boeing airplane, when the computer lowers engine power on autopilot, the engine control lever actually moves in a very visible way. However, on Airbus planes, the levers DO NOT move. The only indication to a pilot that the power has dropped is a small circular readout on a computer screen. The Nova scientists theorized that the pilots didn't realize that the computer had lowered power in anticipation of flying through a thunderstorm, or at least that they realized it too late. They theorize that for about a minute the pilots were flying the plane as if the engines were on high power, when they were actually on a much lower power setting. This, combined with a lack of reliable airspeed data may have caused the pilots to put the plane in an unrecoverable mode of flight. Or maybe it was different. We will know soon enough.
BTW, for those of you outside the US, the above video link won't work. I think the video is on bittorrent somewhere. It is definitely worth watching if you haven't seen it.
Pirates are not new. And through the history of piracy, it has been shown time and time again that to rid the oceans of piracy, the conditions on land that led to the piracy in the first place must be changed. In the case of Somalia, we have a failed state with no real government. Poverty and lawlessness have led to the problem in the oceans off Somalia. Any ocean based solutions to this problem will be merely band-aides. As long as Somalia remains as it is, the piracy problem will continue, battleships and computer games not withstanding.
*Now*, after we shot their Afghan allies and blew things up inside Pakistan, they care about us enough to be a threat. But in 2000, they only threatened to (sic) their neighbors.
That is a gross oversimplification. First off, it IS in our interests to prevent nuclear war between Pakistan and India. Setting the precedent of a modern nuclear shooting war would be very dangerous to world stability. Secondly, you seem to ignore the complex nature of the Pakistani government and power structure. If Afghanistan was to again come under the sway of the Taliban, it would help to give those "scary elements" of the Pakistani power structure more power and influence. There are moderates in Pakistan, but they have a tenuous grasp on power. If the balance tips too far towards extremists, the results could be dangerous. Do you really want a fundamentalist government in charge of nuclear weapons? They could send one of those weapons in a cargo ship to an American city very easily. If they are sufficiently fundamentalist and irrational, then the usual calculus of deterrents will not occur to them.
The success of the Iraq mission is an open question...we will not know for a few decades.
It has already been acknowledged as a failure. The purpose of the Iraq mission was to establish a counter-balance to Iran. That has not happened. It is doubtful that it will ever happen.
Yes, perhaps. But there is no despot in power now. My initial worries about the Iraq war still apply. Iraq was set up with a Sunni minority in power over a Shiite majority. I suppose it was implicit in this arrangement that that minority would exert a forceful influence on the majority it ruled. The risk of shattering this system was civil war from the tensions built up under the old regime. Still, Saddam was truly a despot. Where Iraq goes from here is I believe still up in the air. They have experienced the forceful hand of a dictator and the chaotic results of his absence. They likely understand now the need for a strong government to bring order and stability.
You make the (very terse) argument that "the purpose of the Iraq mission was to counter-balance Iran". Bringing a form of democracy to a society where the majority is Shiite would seem likely to bring the Shiite factions more power. Since Iranians are also mainly Shiite, this would seem to be counterproductive in limiting the power of Iran, so you do have a point. Still, I don't think the matter is anywhere near as simple as this. It remains to be seen what will happen in Iran in the next twenty to thirty years, let alone what happens in Iraq. Younger Iranians are different from their parents, and will probably not put up with the religious tyranny that they live under now. Which is why I think we will not understand the full implications of the Iraqi invasion for a long time.
Still, I believe this was all a very reckless gamble on the part of the Bush administration. They didn't really seem to comprehend the forces that they were unleashing. They seemed to have the cult-like expectation that free markets would unleash a wave of prosperity and peace. One can see this from the fact that they devoted so few troops to the endeavor, and seemed to have done almost no planning as to how to "keep the peace" after the dust settled. In some sense even worse were their fallacious justifications for going to war; they were almost comedically false. They say the first casualty of war is truth, but this war went much farther I believe than past wars. Seeing American troops vainly searching for mobile chemical weapons factories brings to mind images of a malevolent Don Quixote.
So why did we invade and occupy Iraq and Afghanistan?
The success of the Iraq mission is an open question...we will not know for a few decades. Certainly it was very poorly executed, with a shortage of necessary troops that resulted in many years of chaos. As to the Afghan situation, it is obvious why we are there. Pakistan has nuclear weapons. That is it. Period. Let me explain:
Pakistan has a very strange government and political situation. There are forces that tend to be very anti-western and tend to a more fundamentalist religious bent. And there are forces that are more pro-western, Benazir Bhutto being a prime example. Their intelligence services have some strong anti-western members. Pakistan walks a tightrope, being pulled both ways by these forces. AND THEY HAVE NUCLEAR WEAPONS. The fear, probably justified, is that if the Afghan government falls, and the Taliban comes in to fill the power vacuum, this will strengthen the anti-western forces in Pakistan, possibly resulting in a fundamentalist anti-western government with access to nuclear weapons. Since fundamentalists tend to view the world in more absolutist black and white terms, it would seem more likely that they would actually use their nuclear weapons, either against nuclear armed India, or against American targets.
You can debate about the strength of the above argument, but I think it is reasonably certain that this is the type of thinking that is keeping us in Afghanistan.
Of course, since OpenStep was pretty much doomed
I believe that OpenStep and/or its progeny are integrated into OSX and iOS, which is one of the reasons that Apple can swap around it OS's onto various CPU designs so easily. Think of the transition from PowerPC to Intel, or the other chips that run the iPhone/iPod Touch/iPad. This is a huge competitive strength, and is likely a key reason for the success of Apple.
I always was very hesitant to provide Sony with my credit card. I simply don't trust them. I hate the way the PS3 always tries to dump you into the Playstation Store. It just feels obnoxious and disrespectful. And now hearing about their technical negligence, I am even more happy with my decision. Honestly, I have never had any need or desire to buy anything on PSN.
I have replaced most of the light bulbs in my house with CFL's. Here is my experience:
Firstly, buy the good ones. I use Phillips. The open coil kind, and not the ones that come already surrounded by a glass dome. The glass dome ones have an irritatingly long warm up time. The good ones are the ones where you can touch the coil directly.
The bulbs that I use have a fairly good color. I have used the cheap ones, and their color was awful, reminiscent of the lighting at a typical swimming pool. The Phillips bulbs have a color that is nearly indistinguishable from regular bulbs. And they come on almost instantly, and are at full brightness almost right away. The only incandescent bulbs I use are in my nighttime dimmed reading lights. I like the nice warm orange glow of a dimmed 40W incandescent bulb just before bed. Other than that they do work great. They DO work in washrooms. They DO work inside light enclosures. And you won't really notice the difference, except on your power bill.
What would happen to the Earth if the sun suddenly disappeared?
Under Einstein's Theory of Relativity, nothing can travel faster than light. If the Earth "disappeared", or some reasonable facsimile, it would take 7 - 8 minutes before we stopped receiving sunlight, since that is the time for light to travel from the Sun to the Earth. The Sun's gravity is what keeps pulling the Earth in a circular path...without it the Earth would travel in a fairly "straight line". If the Sun suddenly disappeared, its gravitational influence would also disappear. But Einstein's theory implies that nothing can travel faster than light, so the gravitational change caused by the Sun's disappearance cannot reach us sooner than 8 minutes, since otherwise this would imply that the gravity disturbance could exceed the speed of light.
Einstein's General Relativity implies that objects with mass cause distortions in space. It is these distortions that we experience as gravity. The distortions are rather difficult to visualize, however. To really see them in your mind, you have to be able to think in four spacial dimensions. The typical way of making spacial distortion easier to visualize is to reduce space to 2 dimensions. Then you can imagine that space is like a flat rubber sheet. Place a ball on the sheet, and it creates a distortion, as the ball pushes the rubber sheet down. The rubber sheet is still 2 dimensional, but to see the distortion we need to step back and look at it from our 3rd spacial dimension. Now extend space to 3 dimensions. Objects with mass have a similar distortional effect on 3 dimensional space, but to see the distortion, we have to step into the 4th spacial dimension.
If the Sun did disappear, the change in the spacial warping would radiate outwards from the former location of the Sun at the speed of light, kind of like a wave on a pond through 2 dimensional space, though actually in 3 dimensions, with the distortion really only "visualizable" by looking at space from a fourth dimension. It's tricky stuff...General Relativity, which is really Einstein's theory of gravity, is usually only studied seriously in grad school physics.
It is only a small part of the article. Without graphs, and without without references. To anyone seeking to use this for academic purposes it would be largely useless. Still...
Here are a few paragraphs of the original article:
Spectroscopy is a method typically used to assess an unknown quantity of energy by means of a frequency measurement. In many problems, resonance techniques1, 2 enable high-precision measurements, but the observables have generally been restricted to electromagnetic interactions. Here we report the application of resonance spectroscopy to gravity. In contrast to previous resonance methods, the quantum mechanical transition is driven by an oscillating field that does not directly couple an electromagnetic charge or moment to an electromagnetic field. Instead, we observe transitions between gravitational quantum states when the wave packet of an ultra-cold neutron couples to the modulation of a hard surface as the driving force. The experiments have the potential to test the equivalence principle3 and Newton’s gravity law at the micrometre scale
Generally, a quantum mechanical system that is described by two states can be understood in analogy to a spin-1/2 system, where the time development is described by the Bloch equations, assuming two states of a fictitious spin in the multiplet, similar to spin-up and spin-down states. In magnetic resonance of a standard spin-1/2 system, the energy splitting results in the precession of the related magnetic moment in the magnetic field. Transitions between the two states are driven by a transverse magnetic radio frequency field. Similar concepts can be applied to any driven two-level system, for example in optical transitions with light fields. Variations are inherently connected to high-precision measurements such as atomic clocks6, atom interferometry7, nuclear magnetic resonance8, quantum metrology9 and the related spin-echo technique10. The sensitivity reached so far11 in the search for the electric dipole moment of the neutron is 6.8×1022eV, or one Bohr rotation every six days.
In this Letter, we demonstrate that energy eigenstates in the gravity potential of the earth can be probed using a new resonance-spectroscopy technique, using neutrons bounced off a horizontal mirror. This spectroscopy technique has in common the property that a quantum-system is coupled to an external resonator. Quantum mechanical transitions with a characteristic energy exchange between the coupling and the energy-levels are observed on resonance. A novelty of this work is the fact that the quantum mechanical transition is driven by an oscillating field that does not directly couple an electromagnetic charge or moment to an electromagnetic field. Instead, we observe energy transfer on resonance that is based on gravity-quantum states coupled to a modulator. We have named this technique gravity resonance spectroscopy, because the energy difference between these states has a one-to-one correspondence to the frequency of the modulator, in analogy to the nuclear magnetic resonance technique, where the energy splitting of a magnetic moment in an outer magnetic field is related to the frequency of a radio-frequency field. This is possible because of the feature of the quantum bouncing ball12, 13 that the levels are not equidistant in energy. The linear gravity potential leads to measured14, 15, 16 discrete non-equidistant energy eigenstates |nright fence. A combination of any two states can therefore be treated as a two-level system, as each transition can be addressed by its unique energy splitting or, in our case, by vibrating the mirror mechanically at the appropriate frequency. It has also been proposed to realize transitions between gravitational quantum states by means of oscillating magnetic gradient fields17. The physics behind these transitions is related to earlier studies of energy transfer where matter waves bounce off a vibrating mirror18, 19 or a time-dependent crystal20, 21. In the latter case the transitions are between continuum states, in the quantum bouncer the transitions are between discrete eigenstates. Optical dipole traps of atoms are reviewed in ref. 22.
It doesn't predict the bending of light
Err...sorry. I should have said it doesn't predict the bending of light in gravitational fields.
Wow, my physics courses apparently forgot to mention that Newton's Law of Gravity had anything to say about the quantum states of neutrons. In fact, I was taught it's not a law; it's a falsified hypothesis.
Newton's Law of Gravity can be seen as an approximation of Einstein's theory. We have to be careful when we speak of "falsified". We haven't discovered that gravity is proportional to 1/r, or that gravity isn't attractive but repulsive. We have discovered that Einstein's models are better predictors of experimental results. We can still us Newton's models to send humans to the Moon. But Newton's model makes no sense when asking questions such as "what would happen to the Earth if the Sun suddenly disappeared. It doesn't predict the bending of light, nor does it properly describe certain orbital phenomenon.
Reader NotSanguine points out another study which challenges the idea that the brain is more important to the structure of language than cultural evolution.
Perhaps we should not forget the evolution of the structure of our tongue, mouth, and vocal chords in the evolution of language.
Steve Jobs was right.
Trains are infinitely more comfortable than any other form of transportation, high speed or not. You can get up and walk around, go to the restaurant car, and stretch your legs out in widely spaced seats. The motion of the train is gentle and relaxing, and the view out of the train is often beautiful.
Trains are sometimes perceived as being more expensive than cars, but that is largely because the government maintains the roads "for free", while train companies have to maintain the tracks and pay for it using fare revenue. It makes me angry that our society has chosen to let our passenger railway infrastructure to decay. Passenger rail is vital to our national interest, especially in this world of rising fuel prices.
You haven't addressed my assertion that the highly progressive income tax system of the 1950's greatly strengthened the American middle class.