Actually we can do better than that. The arrow of time is baked into fundamental particle physics and we have known this since the 1990's when an experiment, CPLEAR, showed that kaons turn into anti-kaons at a different rate than they switch back. This is completely independent of entropy and the result was further improved on by the Babar experiment only a few years ago showing that the 'T violation' occurs in B-mesons as well.
The article is wrong when it says that the laws of physics work the same going forwards or backwards in time. They do not and there is data to prove it. So the 'arrow of time' does not need any entropy to define it - it is baked into fundamental particle physics.
Pro tip: "afternoon" means before sunset, by definition.
Clearly you are not a pro at English and should not be giving tips. 'Afternoon' means, quite literally, after noon. Evening is usually taken as roughly from 6pm to ~10-11pm. Those living further north in the arctic circle still have a morning, afternoon and evening even if the sun does not rise at all.
gee I hope the third rail contacts on the electrical train I road to work don't hear you
If you 'road' your train then wearing down your third rail is not really an issue...the screaming pedestrians and motorists trying to get our of your way might be a bigger problem though.
a homeowner can buy a device called a tracker that will pivot them
For those of us up in Canada or Northern Europe you need to mount the pannels on a vehicle which heads a long way south or west trailing a cable if they are going to be pointing at the sun in the late afternoon since the sun sets here around 15:30-16:00 this time of year. Simply pivoting or pointing west is just not going to cut it.
Possibly because it often isn't coding in real C++. In ATLAS, and particle physics in general, we use this awful data analysis package called ROOT which is about the worst example of C++ code you can possibly imagine (although it has significantly improved over the years). This package uses a C++ interpreter so that you can write C++ scripts. Sadly this interpreter cannot implement the full set of C++ so major bits of functionality are missing like virtual functions so it's hard to really call this C++.
Unfortunately, while there are many issues with ROOT, it is incredibly fast at I/O and has lots of features which do what we need (if you can navigate past the bugs, memory leaks and dodgy documentation). One way to do help with this is to use the Python interface so many of us use the Python interface as a shield from the full horror of ROOT. The other alternative is to write compiled C++ code which gives you the complete C++ functionality but still leaves you with the minefield of linking to ROOT. To give an example of how bad this can be a few years ago they had a bug which made you code dependent on the comments i.e. by adding a comment line the code generated a duplicate symbol error when linked. After a day of tracking this down to a pre-processor macro I was told by the root development team that they already knew about this bug but could not fix it...that was also the day I switched to using the Python interface!
It's probably just more leverage to encourage people not to drive drunk.
Agreed but they had better not make any mistakes and accuse someone who does not subsequently get convicted. While it is hard to see how someone arrested for drunk driving would be not convicted they do have a history of mistakes like this. A few years ago they busted an online child pornography ring and then went around and named people whose credit cards were used without stopping to think that some of those cards were stolen and used fraudulently.
I'm all in favour of doing what we can to stop drunk driving but deliberately naming and shaming people before they have a conviction is dangerous at best and just plain wrong if those people are not found guilty.
Clearly you have never done experimental physics. Not only are there plenty of 'back of the envelope' calculations that would take far longer to input into a CAS system than to solve but we also use notation that I've no clue how to put into a CAS system. For example in the Standard Model Lagrangian I have 'vectors' to represent spin and colour. These are written into the same term as a multiplication and yet each colour vector must only multiply with colour matrices and other colour vectors. This is achieved by the summation convention but I've never seen a CAS system that supports this properly in a way that is simple enough for 'everyday' calculations.
I can just see having to explain to a 7-year-old-child that heard about the program and doesn't understand why he can't try to be involved that it's because he's a boy.
We've already had to have that conversation with our 10 year old son. The Engineering faculty of our local university runs a Raspberry Pi programming course...but only for girls. My wife contacted them to ask about programs for our son. The super enthusiastic airhead who responded suggested that they had lots of programs for boys but really it boils down to a few places in a summer program and even then much of that program is for girls only. My wife got as far as asking them how their blatant sexism was consistent with the Alberta Human Rights act but got a typical email full of PR but empty of content. In the EU such practice would actually be illegal under gender discrimination laws in Alberta it is less clear since they have this get-out clause 'unless there is a justifiable reason'.
So we had to explain that there were no programs for him because he is a boy which he had a really hard time understanding because he has always been taught that sexism is wrong. Since actions speak louder than words this has undermined the lesson that he had learnt and I've already heard him once tease his older sister that she shouldn't use computers until she has had the 'special lessons for girls'! So as a scheme to eradicate sexism this is an epic way to shoot yourself in the foot. Even simple logic tells you that you cannot eradicate sexism while actually practicing it!
After being forced to write papers in cursive as a child, you get to college... banned. Just straight out banned. You can hand print, or computer print.
Really? Wow. You do all your exams on computer? None of them are handwritten, not even the maths and physics exams?
Fair point but there is one type of writing where typing is really terrible: mathematical notation. It is far, far faster for me to do calculations on paper with a pen than it is to use a computer. If I want it to look neat then writing LaTeX is a clear winner but typing expressions into LaTeX is a lot slower than just jotting them down. So for working things out paper and pen is so far the best there is even in the 21st century.
Not entirely - it tells you the number of write cycles each cell has: 5*365=1,825 cycles. You then just have to hope that the load leveller knows what it is doing because a single file like a mailbox could easily exceed that in a day if the writes were always to the same location on the disk.
Well a C90 tape had a 90 minute length and, depending on you computer the data was written at 1200 baud (BBC Model B) to ~1500 baud for a ZX spectrum. Unfortunately there was some overhead so lets say this was 20% (guesstimate). This would give a tape capacity of 90x60x(1200/8)x0.8=648000 bytes or ~633 kB. Some people used to use C120s which would get you an extra 33% but those tapes were thinner and more likely to break or suffer degradation in sound quality which meant you lost your program. With a Spectrum and a C120 you'd might be pushing the dizzying heights of a whole MB on tape.
If the human knows that the robot is an autonomous killing machine the only rational approach is that the robot is dangerous at all times and must be treated as such.
The premise that this is the only rational approach is wrong though. Suppose you lived in a town where the only way to keep armed militants off the streets was to have those streets patrolled by robots programmed to shoot anyone carrying a gun? If you stay away from the robots you will be going into areas far more dangerous where the likelihood of getting short by some extremist is higher than the likelihood of getting shot by a malfunctioning robot.
If the alternative to the robot is something even more likely to result in serious harm or death then it is entirely rational not to run away from them.
Alpha particles are actually the most dangerous form of radiation because they are the most highly ionizing and so they cause the most damage to cells. While this also makes them the easiest to shield (even a fair amount of air will stop them) their danger lies from either direct skin contact or from consuming something contaminated by them.
The half life is not all that long on the isotopes used in RTGs
You do realize that there is a decay chain right? The next one in the sequence has a half life of 246,000 years and it carries on after that ending at some stable isotope of lead.
No military has ever put dirty bombs in to inventory. The reason is that they are really not effective weapons.
Correct. However there is a difference between deliberately trying to destroy something and accidentally doing so. No military has ever used a nuclear power station as a weapon. Are we therefore to conclude that they are completely safe and pose zero risk of contaminating the environment? The question is not whether these things are a deadly weapon the question is whether they are dangerous. Plutonium is also extremely toxic chemically.
Even if these batteries can be made safe enough to launch, and I don't doubt that they could, you have to prove that which will require a considerable engineering effort potentially making them more expensive than the budget will allow. In addition Pu-238 has a very limited supply.
Testing is done by firing the battery from an artillery gun directly into a solid steel wall several feet thick.
...and did they heat it up to however many thousands of degrees it would reach during re-entry first? That's assuming it simply didn't burn up in the atmosphere first like many meteorites, some of which have very high metal content.
What you are getting is the reconstructed data. To be able to do anything scientifically valuable with it you have to understand the intricate details of the reconstruction software, the trigger, the calibration etc. etc. To be honest I would be amazed if anyone outside CMS will be able to do much with it at all. I'd also expect that there will be bandwidth restrictions on accessing the data since the dataset is multi-PB (if it is the full set of run I data).
We did a similar exercise with the D0 experiment at Fermilab several years ago and it was of interest to practically nobody. I expect there may be somewhat more interest with this being the LHC data but I'd be surprised if anything useful comes of it given the massive amount of work required to be able to do a useful analysis. The best I can think of is that this might make a really nice undergraduate course project or, with some pre-written, high level analysis code, perhaps even as outreach for high school students.
In England this would be covered under Fraud Act 2006 sections 2, 4, 6 and 7 (that's 4 separate INDICTABLE criminal charges with a concurrent maximum sentence of ten years).
You are talking rubbish. Organizations issue fines all the time in the UK e.g. libraries can fine you if you are late returning a book etc. I doubt every library has a sworn judge and a panel of jurors on hand to adjudicate your fine.
Any organization can levy a fine through an agreement. Students typically sign that they agree to be bound by the terms of the university's code of student conduct in before they are allowed to enrol. That code will undoubtedly contain the relevant clauses allowing a discipline procedure to levy a fine on the student. Even without such a signed agreement the fine can still be enforced with the threat of losing you membership of the organization should you fail to pay.
I can't see any way that any of the above constitutes false representation or abuse of position and section 6 and 7 have to do with possession, making and supplying articles for use in fraud (did you even read the act before citing it?).
This is certainly not the behaviour you would expect from a university and I am frankly amazed that they are doing this to their own students. However if it is done within the discipline framework of the university and the students have signed on to follow that code then I would expect that their choices are limited to either paying it or dropping out and finding a better university to attend.
I was ignorantly assuming that they'd do everything they could to insure the accomplishment of the mission.
They almost certainly did within the allowed budget. There are two problems with nuclear power spacecraft. The first is that if something goes wrong on takeoff you risk what is effectively a 'dirty bomb' going off somewhere in the Earth's atmosphere which is not good. The second, which does not apply in this case, is that if you make it into space safely you had better make sure that the craft does not return for Earth for a few billion years otherwise, again, it is like a dirty bomb going off in the atmosphere.
Clearly deep space missions like this mean that there is no chance of return but you still have the risk of a disaster on launch which is not entirely uncommon as the recent Antares Rocket launch showed.
That's not entirely the right question. You need to account for which is more predictable for another human. If you are in the middle of a war zone with soldiers getting blown up by booby traps then you might expect a human soldier to be rather nervous and so you would approach them with extreme caution or get out of the way. However if you have a robot wandering down a street in a peaceful area and the right set of circumstances just happen to cause it to misidentify a random, innocent person as a target that person has no possible way to predict that they need to be extremely cautious.
The result is a complex combination of both a human's ability to know when they are in danger and the predictability of the gun owner. While a human may be more likely to make wrong decisions under pressure fellow humans are also going to be aware of this and take extra precautions. With a robot the decision will be entirely based on how good the robot makes a decision since the human has no way to know whether the robot is likely to be hostile or not.
The fundamental problem with the "standard model" is that it's based on gravity.
Actually the one thing that the Standard Model is absolutely NOT based on is gravity. Gravity being so weak and have an long range actually is responsible for the structures at the largest scales of the Universe which is precisely where we see Dark Matter. The reason for this is that EM is so much stronger that it will force charge cancellation to a large high degree on smaller distance scales: if there is a charge imbalance opposite charges will be rapidly dragged in to create a balance. This cancels EM out at larger distance scales since the charges balance leaving only gravity (the strong and weak nuclear forces being short range [~nucleus] due to their physics).
No, it is very different from the ether. The ether was the proposed medium which light propagated through. As such it was a continuous field not clumps of particles. Also the ether was massless and had no gravitational field. Dark Matter has a mass and causes a gravitational field which is how we know that it exists.
Slashdot Mirror
Actually we can do better than that. The arrow of time is baked into fundamental particle physics and we have known this since the 1990's when an experiment, CPLEAR, showed that kaons turn into anti-kaons at a different rate than they switch back. This is completely independent of entropy and the result was further improved on by the Babar experiment only a few years ago showing that the 'T violation' occurs in B-mesons as well.
The article is wrong when it says that the laws of physics work the same going forwards or backwards in time. They do not and there is data to prove it. So the 'arrow of time' does not need any entropy to define it - it is baked into fundamental particle physics.
Pro tip: "afternoon" means before sunset, by definition.
Clearly you are not a pro at English and should not be giving tips. 'Afternoon' means, quite literally, after noon. Evening is usually taken as roughly from 6pm to ~10-11pm. Those living further north in the arctic circle still have a morning, afternoon and evening even if the sun does not rise at all.
gee I hope the third rail contacts on the electrical train I road to work don't hear you
If you 'road' your train then wearing down your third rail is not really an issue...the screaming pedestrians and motorists trying to get our of your way might be a bigger problem though.
a homeowner can buy a device called a tracker that will pivot them
For those of us up in Canada or Northern Europe you need to mount the pannels on a vehicle which heads a long way south or west trailing a cable if they are going to be pointing at the sun in the late afternoon since the sun sets here around 15:30-16:00 this time of year. Simply pivoting or pointing west is just not going to cut it.
Possibly because it often isn't coding in real C++. In ATLAS, and particle physics in general, we use this awful data analysis package called ROOT which is about the worst example of C++ code you can possibly imagine (although it has significantly improved over the years). This package uses a C++ interpreter so that you can write C++ scripts. Sadly this interpreter cannot implement the full set of C++ so major bits of functionality are missing like virtual functions so it's hard to really call this C++.
Unfortunately, while there are many issues with ROOT, it is incredibly fast at I/O and has lots of features which do what we need (if you can navigate past the bugs, memory leaks and dodgy documentation). One way to do help with this is to use the Python interface so many of us use the Python interface as a shield from the full horror of ROOT. The other alternative is to write compiled C++ code which gives you the complete C++ functionality but still leaves you with the minefield of linking to ROOT. To give an example of how bad this can be a few years ago they had a bug which made you code dependent on the comments i.e. by adding a comment line the code generated a duplicate symbol error when linked. After a day of tracking this down to a pre-processor macro I was told by the root development team that they already knew about this bug but could not fix it...that was also the day I switched to using the Python interface!
It's probably just more leverage to encourage people not to drive drunk.
Agreed but they had better not make any mistakes and accuse someone who does not subsequently get convicted. While it is hard to see how someone arrested for drunk driving would be not convicted they do have a history of mistakes like this. A few years ago they busted an online child pornography ring and then went around and named people whose credit cards were used without stopping to think that some of those cards were stolen and used fraudulently.
I'm all in favour of doing what we can to stop drunk driving but deliberately naming and shaming people before they have a conviction is dangerous at best and just plain wrong if those people are not found guilty.
Clearly you have never done experimental physics. Not only are there plenty of 'back of the envelope' calculations that would take far longer to input into a CAS system than to solve but we also use notation that I've no clue how to put into a CAS system. For example in the Standard Model Lagrangian I have 'vectors' to represent spin and colour. These are written into the same term as a multiplication and yet each colour vector must only multiply with colour matrices and other colour vectors. This is achieved by the summation convention but I've never seen a CAS system that supports this properly in a way that is simple enough for 'everyday' calculations.
I can just see having to explain to a 7-year-old-child that heard about the program and doesn't understand why he can't try to be involved that it's because he's a boy.
We've already had to have that conversation with our 10 year old son. The Engineering faculty of our local university runs a Raspberry Pi programming course...but only for girls. My wife contacted them to ask about programs for our son. The super enthusiastic airhead who responded suggested that they had lots of programs for boys but really it boils down to a few places in a summer program and even then much of that program is for girls only. My wife got as far as asking them how their blatant sexism was consistent with the Alberta Human Rights act but got a typical email full of PR but empty of content. In the EU such practice would actually be illegal under gender discrimination laws in Alberta it is less clear since they have this get-out clause 'unless there is a justifiable reason'.
So we had to explain that there were no programs for him because he is a boy which he had a really hard time understanding because he has always been taught that sexism is wrong. Since actions speak louder than words this has undermined the lesson that he had learnt and I've already heard him once tease his older sister that she shouldn't use computers until she has had the 'special lessons for girls'! So as a scheme to eradicate sexism this is an epic way to shoot yourself in the foot. Even simple logic tells you that you cannot eradicate sexism while actually practicing it!
After being forced to write papers in cursive as a child, you get to college... banned. Just straight out banned. You can hand print, or computer print.
Really? Wow. You do all your exams on computer? None of them are handwritten, not even the maths and physics exams?
That's not a fair comparison.
Fair point but there is one type of writing where typing is really terrible: mathematical notation. It is far, far faster for me to do calculations on paper with a pen than it is to use a computer. If I want it to look neat then writing LaTeX is a clear winner but typing expressions into LaTeX is a lot slower than just jotting them down. So for working things out paper and pen is so far the best there is even in the 21st century.
Such statistics are meaningless in my book.
Not entirely - it tells you the number of write cycles each cell has: 5*365=1,825 cycles. You then just have to hope that the load leveller knows what it is doing because a single file like a mailbox could easily exceed that in a day if the writes were always to the same location on the disk.
I don't know what their capacity was...
Well a C90 tape had a 90 minute length and, depending on you computer the data was written at 1200 baud (BBC Model B) to ~1500 baud for a ZX spectrum. Unfortunately there was some overhead so lets say this was 20% (guesstimate). This would give a tape capacity of 90x60x(1200/8)x0.8=648000 bytes or ~633 kB. Some people used to use C120s which would get you an extra 33% but those tapes were thinner and more likely to break or suffer degradation in sound quality which meant you lost your program. With a Spectrum and a C120 you'd might be pushing the dizzying heights of a whole MB on tape.
If the human knows that the robot is an autonomous killing machine the only rational approach is that the robot is dangerous at all times and must be treated as such.
The premise that this is the only rational approach is wrong though. Suppose you lived in a town where the only way to keep armed militants off the streets was to have those streets patrolled by robots programmed to shoot anyone carrying a gun? If you stay away from the robots you will be going into areas far more dangerous where the likelihood of getting short by some extremist is higher than the likelihood of getting shot by a malfunctioning robot.
If the alternative to the robot is something even more likely to result in serious harm or death then it is entirely rational not to run away from them.
Alpha particles are actually the most dangerous form of radiation because they are the most highly ionizing and so they cause the most damage to cells. While this also makes them the easiest to shield (even a fair amount of air will stop them) their danger lies from either direct skin contact or from consuming something contaminated by them.
The half life is not all that long on the isotopes used in RTGs
You do realize that there is a decay chain right? The next one in the sequence has a half life of 246,000 years and it carries on after that ending at some stable isotope of lead.
No military has ever put dirty bombs in to inventory. The reason is that they are really not effective weapons.
Correct. However there is a difference between deliberately trying to destroy something and accidentally doing so. No military has ever used a nuclear power station as a weapon. Are we therefore to conclude that they are completely safe and pose zero risk of contaminating the environment? The question is not whether these things are a deadly weapon the question is whether they are dangerous. Plutonium is also extremely toxic chemically.
Even if these batteries can be made safe enough to launch, and I don't doubt that they could, you have to prove that which will require a considerable engineering effort potentially making them more expensive than the budget will allow. In addition Pu-238 has a very limited supply.
Testing is done by firing the battery from an artillery gun directly into a solid steel wall several feet thick.
What you are getting is the reconstructed data. To be able to do anything scientifically valuable with it you have to understand the intricate details of the reconstruction software, the trigger, the calibration etc. etc. To be honest I would be amazed if anyone outside CMS will be able to do much with it at all. I'd also expect that there will be bandwidth restrictions on accessing the data since the dataset is multi-PB (if it is the full set of run I data).
We did a similar exercise with the D0 experiment at Fermilab several years ago and it was of interest to practically nobody. I expect there may be somewhat more interest with this being the LHC data but I'd be surprised if anything useful comes of it given the massive amount of work required to be able to do a useful analysis. The best I can think of is that this might make a really nice undergraduate course project or, with some pre-written, high level analysis code, perhaps even as outreach for high school students.
In England this would be covered under Fraud Act 2006 sections 2, 4, 6 and 7 (that's 4 separate INDICTABLE criminal charges with a concurrent maximum sentence of ten years).
You are talking rubbish. Organizations issue fines all the time in the UK e.g. libraries can fine you if you are late returning a book etc. I doubt every library has a sworn judge and a panel of jurors on hand to adjudicate your fine.
Any organization can levy a fine through an agreement. Students typically sign that they agree to be bound by the terms of the university's code of student conduct in before they are allowed to enrol. That code will undoubtedly contain the relevant clauses allowing a discipline procedure to levy a fine on the student. Even without such a signed agreement the fine can still be enforced with the threat of losing you membership of the organization should you fail to pay.
I can't see any way that any of the above constitutes false representation or abuse of position and section 6 and 7 have to do with possession, making and supplying articles for use in fraud (did you even read the act before citing it?).
This is certainly not the behaviour you would expect from a university and I am frankly amazed that they are doing this to their own students. However if it is done within the discipline framework of the university and the students have signed on to follow that code then I would expect that their choices are limited to either paying it or dropping out and finding a better university to attend.
Uh, nuh. Pu238 half-life is 88 years.
Correct but it does not stop there. It decays into an isotope with a 246k year half life and so on down a decay chain which eventually ends at lead.
I was ignorantly assuming that they'd do everything they could to insure the accomplishment of the mission.
They almost certainly did within the allowed budget. There are two problems with nuclear power spacecraft. The first is that if something goes wrong on takeoff you risk what is effectively a 'dirty bomb' going off somewhere in the Earth's atmosphere which is not good. The second, which does not apply in this case, is that if you make it into space safely you had better make sure that the craft does not return for Earth for a few billion years otherwise, again, it is like a dirty bomb going off in the atmosphere.
Clearly deep space missions like this mean that there is no chance of return but you still have the risk of a disaster on launch which is not entirely uncommon as the recent Antares Rocket launch showed.
I know that but I guess the joke was lost on you.
Which is more likely to shoot a civilian...
That's not entirely the right question. You need to account for which is more predictable for another human. If you are in the middle of a war zone with soldiers getting blown up by booby traps then you might expect a human soldier to be rather nervous and so you would approach them with extreme caution or get out of the way. However if you have a robot wandering down a street in a peaceful area and the right set of circumstances just happen to cause it to misidentify a random, innocent person as a target that person has no possible way to predict that they need to be extremely cautious.
The result is a complex combination of both a human's ability to know when they are in danger and the predictability of the gun owner. While a human may be more likely to make wrong decisions under pressure fellow humans are also going to be aware of this and take extra precautions. With a robot the decision will be entirely based on how good the robot makes a decision since the human has no way to know whether the robot is likely to be hostile or not.
The fundamental problem with the "standard model" is that it's based on gravity.
Actually the one thing that the Standard Model is absolutely NOT based on is gravity. Gravity being so weak and have an long range actually is responsible for the structures at the largest scales of the Universe which is precisely where we see Dark Matter. The reason for this is that EM is so much stronger that it will force charge cancellation to a large high degree on smaller distance scales: if there is a charge imbalance opposite charges will be rapidly dragged in to create a balance. This cancels EM out at larger distance scales since the charges balance leaving only gravity (the strong and weak nuclear forces being short range [~nucleus] due to their physics).
No, the reason the Higgs is called the god particle is because you can't have Mass without it.
No, it is very different from the ether. The ether was the proposed medium which light propagated through. As such it was a continuous field not clumps of particles. Also the ether was massless and had no gravitational field. Dark Matter has a mass and causes a gravitational field which is how we know that it exists.