Most particle physics happens on much faster time scales than picoseconds. There is some slower physics but that can generally be measured by looking at the verticies where tracks diverge and calculating the time it too particles to get to those vertices.
For measuring beams rather than the individual particle collisions we can use transverse deflection structures (a sort of streak-camera on steroids) to get to resolutions of a few femtoseconds.
The original article is a nice technique, but whether it is the fastest depends on how you define "camera". It is probably the fastest for 2-d images, but there are much faster 1-d imagers.
The test was done in air. There are a huge number of possible sources for thrust. Most notable are convection currents from temperature differences. Even if the test is done in vacuum, you need to be very careful. Temperature changes can cause out-gassing. Thermal radiation will generate force from photon pressure.
Newtonian physics was (and still is) extremely accurate in the range in which it was tested. The flaws were found under new conditions (relatively strong fields and fast motions of planets, and detailed measurements of the speed of light).
The amount of physics knowledge now is vastly greater than it was in 1900. My day job involves working with electrons at.99999999C. As I sit here I am looking at the energy of X-rays generated from scattering off of 12 GeV electrons - getting the correct energy relies on conservation of mass energy. Conservation of mass-energy is measured in everything from planetary orbits, to electron diffraction, to neutron star binaries, to high energy collisions.
This device is not operating in any new physical regime. The energies and length scales are quite modest.There is no physical explanation of what is going on (quantum mechanics conserves mass-energy). Its a very dirty experiment (done in air etc), so it is enormously more likely to be a mistake than the discovery of a new physical principal.
So if there is a child-porn detection tool, is it available to the public to automatically block an illegal images from web sites and email? I don't know if the database is just things that are obviously child porn, or includes nude pictures that are not obviously underage.
I'm not sure of the legal implications of a botnet spamming millions of people with illegal images. Most users do no know how to erase all of the copies from cache.
Which seems like a great way to catch the minor offenders who are trading old pictures, but not the really serious offenders who are producing NEW child porn. One could even argue that it creates a market for new child porn that doesn't have known signatures.
I wonder if child porn is the only type of material that is checked against a known database?
People often miss that the problem with ion drives and other electrical drives is that the exhaust velocity is too HIGH, not too low.
The higher the exhaust velocity, the more power you need for the same thrust. Making high specific impulse drives is easy - a microwave source can be ~80% efficient and has an exhaust velocity of the speed of light. The problem is that the power requirements are enormous.
Sure, energy from the sun is "free", but the mass of the solar cells to collect that energy is not free. With a speed-of-light drive the thrust to weight ration is exceedingly small for conventional power sources (which includes nuclear and solar) so the acceleration is too small to be useful for most applications.
If you imagine a solar powered spacecraft, you need to be sure that over the lifetime of the mission you would get more total velocity change out of the solar cells and electrical drive than you would from the same weight of chemical rockets. For ion drives and long missions this is true, but for a photon drive (or any other propellant-free drive it is not true for any reasonable length mission).
Some NASA employees are experts, but that doesn't mean that all NASA employees are experts.
If the thrust is only proportional to the photon pressure from microwaves, then this is not particularly interesting.
If the thrust is from somehow accelerating ions, electrons, or ambient air molecules, this is not particularly interesting. (just a different type of ion drive)
If there is thrust with no exhaust, if it doesn't conserve momentum, then the device is impossible. Yes, IMPOSSIBLE. Conservation of 4-momentum is among the best tested bits of physics. "quantum mumble" doesn't change that - quantum mechanics also conserves momentum.
The particularly stupid part was messing with their match algorithm. If they imply that their algorithm has any value, then their users will feel at least ripped off (since the algorithm doesn't seem to work well), and possibly angry because they were given incorrect information .
Blocking pictures was visible to users and I don't have any problem with that .
There are a variety of tradeoffs between circular and linear electron / positron machines. At very high energies (>~500GeV CM) the circular machines become impractical At low energies (100 GeV CM) a circular machine is considerably simpler and cheaper. Inbetween the trade-offs are not completely obvious.
EXACTLY. I would much prefer streaming if the same content were available but it isn't. In particular many recent releases are only available in physical disks. If netflix wants to go to an all streaming model it needs to talk to its suppliers, not its customers .
I'm particularly amused that people seriously considered nuclear bomb pulse propulsion for EARTH TAKEOFF. And to think modern wimps complain about airport noise.....
US may be more like Byzantium, a slow centuries-long decline. Reliving its past glories "safe" behind its invulnerable walls.
Civilizations rise and fall. Its not clear who's next. China is making rapid progress, but it isn't clear if they will regain their millennia long place as world leaders, or crash and burn on the next economic downturn. I hope they make it though - I'd rather it were us, but I want someone in space.
While I agree with this, I think there is also the issue that the shuttle was not a very good general purpose launch vehicle - or more correctly general purpose launch vehicles do not seem like a good engineering solution.
For missions where you need to send men and equipment into orbit and bring them down again the Shuttle is fine. If you just want to put cargo into orbit, the extra weight and complexity is not worth it. If you just want to put men in orbit and return them, then a smaller vehicle works.
The design of launch vehicles is so marginal that it is not worth providing for a lot of mission flexibility. The early shuttle concepts recognized this and had non-returning heavy-lift variants.
I check in online. When I get to the airport, why can't I just swipe my passport drop my bags on the conveyor and go on my way. Sometimes that works, but at least half the time while someone types the Oxford English Dictionary into a keyboard. I'm not changing flights. I'm doing exactly what my reservation, and online checkin said I was doing.
I don't want a human touch, I just want to get on my airplane.
On the occasions where I am doing something unusual, or where something goes wrong, an AI avatar is NOT going to be able to solve my problem.
Assuming CATIIIc zero visibility operations will be approved, a lack of windows should be fine for normal taxi and flight. The pilots are already relying on operating entirely by instruments.
That said, there could be emergencies where real outside visibility would be nice - water ditching, etc. Those may be rare enough though that it isn't a significant extra risk.
Will sure may flying airliners even less interesting than it is now.
I think part of the problem is that what we think of as "intelligence" is a vector quantity and can't be well described by a scalar like IQ. You can define some metric on the vector intelligence, but that metric will be arbitrary. You can think of "intelligence" as a combination of memory, quick-thinking, spatial visualization, abstract mathematical ability, social abilities, etc etc. What combination of those are important will be different depending on what activity you are doing.
The particular problem here is that most people want intelligent companions in order to have interesting conversations. I don't think the standard IQ measurement is a good indicator of how interesting someone is to talk to.
I think most people just naturally find others with compatible ways of thinking. So using IQ to find companions who are also looking for high IQs may be pre-selecting for people who are not very good at socializing. Its not that high IQ makes you bad at socializing, but rather that if you are good at socializing, you won't need to use IQ to pre-select.
The lack of a formal declaration of war is one problem. The other is the idea of a "global" war on terrorism. In a conventional war, someone operating within an enemy country can be considered an enemy and is reasonable target for an attack. The geographic limits on targets put a limit on the ability of the US to simply execute citizens. An American citizen in an enemy country is a legitimate target of attack in the same way that (with some restrictions) anything else in that country is a valid target. However, military attacks when there is not a state of war with a country are normally not considered legal.
With this "global" war on terrorists, we are essentially saying that we can declare anyone anywhere to be an enemy, and then kill them. By this logic could China use a drone to kill an Chinese citizen in the US if they believe he holds a high position in Falun Gong? Could this argument be used to execute rather than arrest a US citizen IN the US if his capture was believed to be too dangerous?
It seems to be a dangerous blurring of the line between law enforcement and war.
But all of this information comes from the same government that executed him. Its very likely he was involved, but did his involvement rise to the level of a capital crime? Is there even a death sentence for conspiracy to commit murder?
That IS a major turning point. There is a huge difference between occasionally killing people in secret and declaring that the government has the right to kill citizens without a trial. Secret killings need to be limited in number or they can't be kept secret. Once execution without trials is in the open, what limits the numbers?
If you are in a state of war with a country, within some limits it is expected that you can kill people in that country. Where things get complicated is when you are in an ill defined state of hostility against a non-state organization like Al Qaeda. What are the rules on declaring someone to be part of that organization and there for a military target? While this question applies to any possible targets, it is especially troublesome when the target is an american citizen. The government cannot execute an american citizen without a trial. Can it declare an american citizen to be a member of a foreign military and then execute them? This would seem to completely bypass the constitutional right to a fair trial.
In a standard state-war it is fairly simple: If they are in an enemy country it is OK to kill them in the same way that it was OK to kill anyone else in that country. An american arrested for treason in the US on the other hand would get a trial. In a conventional state war you don't bomb countries that are not enemy states.
The level of activity to be considered a target for execution is also a tricky question. It is clearly OK to return fire if fired upon. When his actions are less direct it becomes more difficult.
At the root of all this is that the concept of "war" has changed and laws have not kept up with 21st century wars.
The technology development would be really valuable if you believe in a future for human presence in space (which I do, but which I admit is an almost religious belief). The actual asteroid capture on the other hand seems like a difficult but not particularly interesting stunt. 10M isn't really an asteroid, its a rock. Rocks that size hit the earth regularly.
Personally I'd rather see the solar-electric propulsion developed for large probes, especially an Europa lander / rover, and maybe a Titan lander or boat. The manned launch capability is fine if we are working toward a Mars mission (which I hope we are).
Manned space isn't about science and never was. Neither are the pyramids, the Olympics, National parks, fireworks displays, Christmas, Karaoke, or a huge variety of other things we spend tons of money doing. These things, like manned space flight, are more of a goal, rather than a means.
Shouldn't this be a case of criminal collusion? At the very least it seems punitive damages are appropriate, and those could far exceed the nominal damage done.
A number of labs like SLAC have a salvage department that collects old, but sometimes still functional equipment. If you are associated with an educational institution you might be able to get some of this stuff for free. It will be old but probably fine for some types or student experiments .
The difference between talking about something and doing it is the difference between amusing talk and a crime. We've also talked about putting bitcoin miners in all the high power FPGAs we use for real time feedback. The thing is that we DIDN'T.
As far as the penalty - this is like any other theft of materials. There must be applicable laws.
Slashdot Mirror
Most particle physics happens on much faster time scales than picoseconds. There is some slower physics but that can generally be measured by looking at the verticies where tracks diverge and calculating the time it too particles to get to those vertices.
For measuring beams rather than the individual particle collisions we can use transverse deflection structures (a sort of streak-camera on steroids) to get to resolutions of a few femtoseconds.
The original article is a nice technique, but whether it is the fastest depends on how you define "camera". It is probably the fastest for 2-d images, but there are much faster 1-d imagers.
The test was done in air. There are a huge number of possible sources for thrust. Most notable are convection currents from temperature differences. Even if the test is done in vacuum, you need to be very careful. Temperature changes can cause out-gassing. Thermal radiation will generate force from photon pressure.
Newtonian physics was (and still is) extremely accurate in the range in which it was tested. The flaws were found under new conditions (relatively strong fields and fast motions of planets, and detailed measurements of the speed of light).
The amount of physics knowledge now is vastly greater than it was in 1900. My day job involves working with electrons at .99999999C. As I sit here I am looking at the energy of X-rays generated from scattering off of 12 GeV electrons - getting the correct energy relies on conservation of mass energy. Conservation of mass-energy is measured in everything from planetary orbits, to electron diffraction, to neutron star binaries, to high energy collisions.
This device is not operating in any new physical regime. The energies and length scales are quite modest.There is no physical explanation of what is going on (quantum mechanics conserves mass-energy). Its a very dirty experiment (done in air etc), so it is enormously more likely to be a mistake than the discovery of a new physical principal.
Certainly anyone who emails child porn is stupid.
So if there is a child-porn detection tool, is it available to the public to automatically block an illegal images from web sites and email? I don't know if the database is just things that are obviously child porn, or includes nude pictures that are not obviously underage.
I'm not sure of the legal implications of a botnet spamming millions of people with illegal images. Most users do no know how to erase all of the copies from cache.
Which seems like a great way to catch the minor offenders who are trading old pictures, but not the really serious offenders who are producing NEW child porn. One could even argue that it creates a market for new child porn that doesn't have known signatures.
I wonder if child porn is the only type of material that is checked against a known database?
People often miss that the problem with ion drives and other electrical drives is that the exhaust velocity is too HIGH, not too low.
The higher the exhaust velocity, the more power you need for the same thrust. Making high specific impulse drives is easy - a microwave source can be ~80% efficient and has an exhaust velocity of the speed of light. The problem is that the power requirements are enormous.
Sure, energy from the sun is "free", but the mass of the solar cells to collect that energy is not free. With a speed-of-light drive the thrust to weight ration is exceedingly small for conventional power sources (which includes nuclear and solar) so the acceleration is too small to be useful for most applications.
If you imagine a solar powered spacecraft, you need to be sure that over the lifetime of the mission you would get more total velocity change out of the solar cells and electrical drive than you would from the same weight of chemical rockets. For ion drives and long missions this is true, but for a photon drive (or any other propellant-free drive it is not true for any reasonable length mission).
Some NASA employees are experts, but that doesn't mean that all NASA employees are experts.
If the thrust is only proportional to the photon pressure from microwaves, then this is not particularly interesting.
If the thrust is from somehow accelerating ions, electrons, or ambient air molecules, this is not particularly interesting. (just a different type of ion drive)
If there is thrust with no exhaust, if it doesn't conserve momentum, then the device is impossible.
Yes, IMPOSSIBLE. Conservation of 4-momentum is among the best tested bits of physics. "quantum mumble" doesn't change that - quantum mechanics also conserves momentum.
The particularly stupid part was messing with their match algorithm. If they imply that their algorithm has any value, then their users will feel at least ripped off (since the algorithm doesn't seem to work well), and possibly angry because they were given incorrect information .
Blocking pictures was visible to users and I don't have any problem with that .
There are a variety of tradeoffs between circular and linear electron / positron machines. At very high energies (>~500GeV CM) the circular machines become impractical At low energies (100 GeV CM) a circular machine is considerably simpler and cheaper. Inbetween the trade-offs are not completely obvious.
EXACTLY.
I would much prefer streaming if the same content were available but it isn't. In particular many recent releases are only available in physical disks. If netflix wants to go to an all streaming model it needs to talk to its suppliers, not its customers .
It wasn't even a new building, they just changed the name of an existing one.
Mod parent +1 awesome.
I'm particularly amused that people seriously considered nuclear bomb pulse propulsion for EARTH TAKEOFF. And to think modern wimps complain about airport noise.....
US may be more like Byzantium, a slow centuries-long decline. Reliving its past glories "safe" behind its invulnerable walls.
Civilizations rise and fall. Its not clear who's next. China is making rapid progress, but it isn't clear if they will regain their millennia long place as world leaders, or crash and burn on the next economic downturn. I hope they make it though - I'd rather it were us, but I want someone in space.
While I agree with this, I think there is also the issue that the shuttle was not a very good general purpose launch vehicle - or more correctly general purpose launch vehicles do not seem like a good engineering solution.
For missions where you need to send men and equipment into orbit and bring them down again the Shuttle is fine. If you just want to put cargo into orbit, the extra weight and complexity is not worth it. If you just want to put men in orbit and return them, then a smaller vehicle works.
The design of launch vehicles is so marginal that it is not worth providing for a lot of mission flexibility. The early shuttle concepts recognized this and had non-returning heavy-lift variants.
I check in online. When I get to the airport, why can't I just swipe my passport drop my bags on the conveyor and go on my way. Sometimes that works, but at least half the time while someone types the Oxford English Dictionary into a keyboard. I'm not changing flights. I'm doing exactly what my reservation, and online checkin said I was doing.
I don't want a human touch, I just want to get on my airplane.
On the occasions where I am doing something unusual, or where something goes wrong, an AI avatar is NOT going to be able to solve my problem.
Assuming CATIIIc zero visibility operations will be approved, a lack of windows should be fine for normal taxi and flight. The pilots are already relying on operating entirely by instruments.
That said, there could be emergencies where real outside visibility would be nice - water ditching, etc. Those may be rare enough though that it isn't a significant extra risk.
Will sure may flying airliners even less interesting than it is now.
I think part of the problem is that what we think of as "intelligence" is a vector quantity and can't be well described by a scalar like IQ. You can define some metric on the vector intelligence, but that metric will be arbitrary. You can think of "intelligence" as a combination of memory, quick-thinking, spatial visualization, abstract mathematical ability, social abilities, etc etc. What combination of those are important will be different depending on what activity you are doing.
The particular problem here is that most people want intelligent companions in order to have interesting conversations. I don't think the standard IQ measurement is a good indicator of how interesting someone is to talk to.
I think most people just naturally find others with compatible ways of thinking. So using IQ to find companions who are also looking for high IQs may be pre-selecting for people who are not very good at socializing. Its not that high IQ makes you bad at socializing, but rather that if you are good at socializing, you won't need to use IQ to pre-select.
The lack of a formal declaration of war is one problem. The other is the idea of a "global" war on terrorism. In a conventional war, someone operating within an enemy country can be considered an enemy and is reasonable target for an attack. The geographic limits on targets put a limit on the ability of the US to simply execute citizens. An American citizen in an enemy country is a legitimate target of attack in the same way that (with some restrictions) anything else in that country is a valid target. However, military attacks when there is not a state of war with a country are normally not considered legal.
With this "global" war on terrorists, we are essentially saying that we can declare anyone anywhere to be an enemy, and then kill them. By this logic could China use a drone to kill an Chinese citizen in the US if they believe he holds a high position in Falun Gong? Could this argument be used to execute rather than arrest a US citizen IN the US if his capture was believed to be too dangerous?
It seems to be a dangerous blurring of the line between law enforcement and war.
But all of this information comes from the same government that executed him. Its very likely he was involved, but did his involvement rise to the level of a capital crime? Is there even a death sentence for conspiracy to commit murder?
"al-Aulaqi declared himself an enemy combatant and a member of a group which we are at war with"
Did he? How do you know?
That IS a major turning point. There is a huge difference between occasionally killing people in secret and declaring that the government has the right to kill citizens without a trial. Secret killings need to be limited in number or they can't be kept secret. Once execution without trials is in the open, what limits the numbers?
If you are in a state of war with a country, within some limits it is expected that you can kill people in that country. Where things get complicated is when you are in an ill defined state of hostility against a non-state organization like Al Qaeda. What are the rules on declaring someone to be part of that organization and there for a military target? While this question applies to any possible targets, it is especially troublesome when the target is an american citizen. The government cannot execute an american citizen without a trial. Can it declare an american citizen to be a member of a foreign military and then execute them? This would seem to completely bypass the constitutional right to a fair trial.
In a standard state-war it is fairly simple: If they are in an enemy country it is OK to kill them in the same way that it was OK to kill anyone else in that country. An american arrested for treason in the US on the other hand would get a trial. In a conventional state war you don't bomb countries that are not enemy states.
The level of activity to be considered a target for execution is also a tricky question. It is clearly OK to return fire if fired upon. When his actions are less direct it becomes more difficult.
At the root of all this is that the concept of "war" has changed and laws have not kept up with 21st century wars.
The technology development would be really valuable if you believe in a future for human presence in space (which I do, but which I admit is an almost religious belief). The actual asteroid capture on the other hand seems like a difficult but not particularly interesting stunt. 10M isn't really an asteroid, its a rock. Rocks that size hit the earth regularly.
Personally I'd rather see the solar-electric propulsion developed for large probes, especially an Europa lander / rover, and maybe a Titan lander or boat. The manned launch capability is fine if we are working toward a Mars mission (which I hope we are).
Manned space isn't about science and never was. Neither are the pyramids, the Olympics, National parks, fireworks displays, Christmas, Karaoke, or a huge variety of other things we spend tons of money doing. These things, like manned space flight, are more of a goal, rather than a means.
Shouldn't this be a case of criminal collusion? At the very least it seems punitive damages are appropriate, and those could far exceed the nominal damage done.
A number of labs like SLAC have a salvage department that collects old, but sometimes still functional equipment. If you are associated with an educational institution you might be able to get some of this stuff for free. It will be old but probably fine for some types or student experiments .
The difference between talking about something and doing it is the difference between amusing talk and a crime. We've also talked about putting bitcoin miners in all the high power FPGAs we use for real time feedback. The thing is that we DIDN'T.
As far as the penalty - this is like any other theft of materials. There must be applicable laws.