This is why I constantly emphasis "in a rotating frame of reference". Yes, the centrifugal force is an artifact of the reference frame, but it greatly simplifies the problem to use the rotating frame and add the centrifugal force.
There is nothing wrong with centrifugal force, so long as you clearly understand that it is a mathematical device, rather than physical reality.
I.e. it is not bad physics. It could be accused of being bad pedagogy if your audience doesn't already understand the above. Of course, all/. readers have at least a bachelor's degree in physics, so I'm OK with respect to this.:-)
The fact that a mutation of the FOXP2 gene in the "KE" family causes language impedements does not imply that the gene has anything whatsoever to do with language in normal usage.
Here's an analogy. We have a bunch of variations on a model of car. Some have the exhaust pipe on the left, some on the right. Those with the exhaust pipe on the right frequently have failures of the electrical system - because the hot exhaust pipe is too close to some critical part of the electrical system, causing it to burn out.
Now think FOXP2 gene => which side the exhaust pipe goes on, and electrical system => language system.
(This objection is not original with me - it is raised by Stephen Pinker in one of his books, probably The Language Instinct. It might not be original with him either.)
In general, the article in question looks to me like poorly supported speculation - although that may be an artifact of it having been filtered through a science reporter.
I don't understand how they can base it so far from the equator. If you start the counterweight south of the equator, above Perth, it will be way north of the equator 12 hours later.
In more detail: In a reference frame rotating with the Earth, the counterweight has three forces on it:
Gravity: G m M_earth / r^2 towards the center of the earth 'Centrifugal' force (because we are in a rotating frame): v^2 / r cos l (l = latitude) directed perpendicular to and away from the earth's axis Tension on the cable.
We want these three forces to cancel out, so that the counterweight is stationary (in the rotating frame.) The problem is that the gravity force has a north/south component unless the counterweight is on the equator. The centrifugal force can't have a north/south component, so the balancing force has to come from the cable tension.
The cable will have be at a small angle to vertical, and the north/south component of the tension is proportional to the sine of this angle, so that component can't be big.
Aha! I think I have the solution.I was thinking of the counterweight being above the tether point.
In the 1st approximation, put the counterweight in geostationary orbit (i.e. on the equator). Run the cable to it.
If the cable had no tension, we would done - but it does. The major component of the tension is towards the earth. We compensate for this by moving the counterweight into a higher orbit. (Decreases gravity, increases centrifugal force, to balance the tension.) There is nothing new here - the Highlift Systems website talks about this.
If the cable was anchored south of the equator, it will have a slight angle to vertical, which will give a southwards force component. If we now modify the orbit of the counterweight to be slightly south of the equator, there will be a northward component to the gravity vector. We can adjust to balance.
From the point of view of the tether point, the cable (if it is straight) will be pointing almost towards the geostationary point. From 30 degrees south, that would be a point about 3000 km north and about 35 km up, so it would be about 5 degrees off vertical.
This smells suspiciously of renaming something old so it seems new.
In the early 1980s, the IRAS satellite did an all-sky survey at wavelengths up to 100 micron - i.e. about 3 THz.
The article says "most current radio technology stops at around 100 GHz." I myself have observed at 345GHz (0.345 THz) using radio astronomy techniques, and this was over 10 years ago. (This was at the Caltech Submillimeter Observatory, but it is not the only such observatory in the world.)
There is some new stuff here, however - at CSO, we had only one pixel, and they are talking about a compact 16 pixel detector (working at 0.2 to 0.3 THz - I.e. much the same frequencies as we were using.)
From an astronomical point of view, although detectors are a fairly big issue, our main problem was noise from the atmosphere - i.e. the atmosphere 'glows' at these wavelenghts, which tends to drown out the astronomical objects you are looking for.
If you fitted a grille over the intake of the super water jet engine, you could put out the fire with a more powerfull blast from a more reliable engine and not have any disadvantages like slugging the burning marina with underwater potatoes and sucked up fish.
So you've got fire, fish, potatos and a grill for the potatos to pass through.
And of course complex software systems like this never have bugs, and couldn't possibly lock somebody in a room overnight because the system doesn't belive they can be near the only door.
"HP... will announce customers including ASP Futuro Bolivia, which uses Linux and Oracle 9i RAC using four, four-processor HP servers to manage the pensions of about half the retirees in Bolivia."
An interesting point here is that once you've paid for an Oracle 4 proc license, the cost of adding a proprietry Unix likely won't even change your second-most-significant digit in the price. This means these people believe Linux is better than proprietry, independent of the free/gratis factor.
Many fuel cell products/prototypes use a hydrocarbon fuel (I think typically methane or methanol.) They use a 'reformer' to extract the hydrogen from the hydrocarbon, to pass it to the fuel cells.
This gives a number of options to reduce the problem of setting up the hydrogen distribution network: * Reformer in vehicle. Fuel it with methane (i.e. natural gas - already available on tap in many cities) or methanol (liquid, can use existing petrol/gas station network) or perhaps even ordinary petrol/gas or diesel. (I'm not sure how flexible the reformers are.) * Reformer at petrol/gas station. It gets the feedstock as above, and provides hydrogen to your car. * Piped hydrogen (the network you worry about needing to set up.) This can be set up in stages, due to the above options.
Disclaimer: All this is from memory from popular science/technology articles. I don't know how efficient these things are. I do remember that they need to run hot (about 300C I think.)
Re:Science is open to everyone
on
Who Owns Science?
·
· Score: 3, Insightful
I'm having troubles deciding whether this post is just plain ignorant, or whether it is a subtle parody of the music/napster/copyright/RIAA debate.
Almost all scientific journals charge the researcher money to publish in them. This money is paid from the grant that supported the research activity.
Like almost anyone, academics like to be well paid, but it isn't journal subscriptions that pays any part of their salary.
My first thought on seeing this article was "Hey, somebody's slashdotted the Aardvark!"
Then I looked again at who submitted it - the Aardvark slashdotted the Aardvark!
Are you stress testing your web server, Bruce?
(Along with a few comic strips and/., the Aardvark is one of my visit-every-day sites. Of course, non-New Zealanders will find the site less interesting.)
On the other hand, there are definate failures of peer-review. I am a co-author on a paper that refuted another paper. The original paper should never have passed peer review. The most egregious error was that the energy of a collision was underestimated by something like 12 orders of magnitude. It appears that the error was both arithmetic (failure to convert all quantities to SI units before multiplying) and physical (failure to account for gravitational potential energy.)
Come on, this is a "Score:3 Funny" not a "Score:5 Funny."
I see someone had the sense to put an 'overrated' on it, but evidently someone else undid the good work.
Hm, going off on a tangent in a big way:
A man was holding a very small dinner party, with his father's brother-in-law, his brother's father-in-law, his father-in-law's brother and his brother-in-law's father.
How small can the party be?
(This puzzle comes from the Rev Charles Dodgeson, the famous Victorian photographer, mathemetician and author. As the puzzle is of English origin, first cousins may marry.)
An extension *not* from the Rev Dodgeson: How much smaller can the party become if we ignore incest marrage restrictions? What is the least relaxation on the incest laws to allow this minimum size?
I'm confused. I know what a founder co-founder is (one of the parents of the founder), but what is a co-founder founder? The original from which the co-founder was cloned?
Re:Optical Communications to Keep Bombs Away
on
Optical Cellphones
·
· Score: 4, Interesting
The problem you describe is not "radio broadcast vs optical narrow beam", it is "broadcast vs narrow beam". Once I've decided to go narrow beam for these reasons, why would I go optical rather than microwave?
(The beam divergence is inversely proportional to the number of wavelengths wide your transmitter/reflector is, which means that smaller wavelength requires a smaller transmitter apperature to achieve a given beam divergence, but surely microwaves are good enough, and have much better penetration.)
Very little. 1500 mJ, specificaly. It's done every day.
That is a measure of energy, not of power.
Uhhh... only if you're in the visible light spectrum. Some wavelengths will pass right through clouds (and other objects, like the earth) completely unphased.
Some wavelengths are less affected by cloud than others - I'm *guessing* about 10 microns would be a reasonable compromise between cloud penetration and water vapour (as opposed to droplets) interference.
However, NO wavelength of light will pass through the earth (although you can get some penetration through a few km of ice.) Do you know the difference between a photon and a neutrino?
Here's a quarter, kid. Go buy a clue.
I think you need all your quarters. If you're going to be arrogant, you need to make sure you are also right.
When I was in the final stages of writing my thesis, I had backups on ZIP disks:
One set in the same room as my computer - generally a day or two old. One set in another room in the house - a bit older. One set in another house in the same city. One set (a few weeks old) in my brother's house about 500 km away.
This gave me a good lifeline to sanity when I accidentally deleted my partition table a week before finishing. (In fact, I didn't need the backup - I had the partition table info in hardcopy and just reentered it.)
Now I use my computer mostly for games, so my only backup is that my parents have copies of all my photos.
Mira is 'wonderful' or 'astonishing' in Latin. The first variable star discovered is named Mira. It is about 3rd magnitude at brightest, and invisible to the naked eye at other times.
I don't know if the Latin word or the star had any part in Microsoft's naming.
Inevitably, IANAL, but I'm going to express my uninformed opinion anyhow. (What else is/. for?)
I really don't think this will fly. Just because you've spent money on something, it doesn't mean that nobody else is allowed to do anything that will adversly affect your investment. You may just have made a bad investment.
E.g.: I buy an island and build a luxury resort specifically for celebrities to get away from paparazi. Once I open it, the paparazi start hanging out in boats off shore (a public area). I can't make them go away.
E.g. 2: I build a luxury apartment block next to an airport. I can't sue the airport to reduce noise just because I can't sell my apartments.
E.g. 3: I distribute movies on a medium that allows me to prevent people skipping the ads. Someone starts distributing programs that will play my movies while allowing the ads to be skipped. I can't sue them simply because this has an adverse effect on my advertising income.
E.g. 4: I spend lots of money building up a buggy-whip business...
O.K, looking back at this list, you *shouldn't* be able to sue in these cases.
Reread my post. All I said was that the 'that many people can't keep a secret' argument is weaker than it first appears.
Incidentally, the F-117's existence was not a well kept secret, although the details were. There was even a plastic kitset 'stealth fighter' model sold before the F-117 was unveiled - but it bore little resemblence to the actual plane.
I don't believe these nutcases. However, I recently realized that one of my arguments against them is not as strong as I thought.
Here's the argument: Tens of thousands of people were involved in the Apollo program. There were thousands of them who would unavoidably know if the moon landings were faked. Several thousand people can't keep a secret for over 30 years.
What is wrong with this argument? Bletchley Park. For about 30 years, several thousand people kept the secret that the allies hand broken most of the axis codes during World War II.
(It is still a valid argument, however - there are differences between Bletchley Park and a hypothetically faked Apollo 11.)
Robert Cringley had an interesting take on this in one of his old weekly columns.
"The single most driving force in the development of Bill Gates today or any day is his competitive nature. The guy simply has to win, and will do pretty much whatever it takes to succeed.... And if he can't win, then he'd rather not play."...
"The Bill and Melinda Gates Foundation has committed $750 million to childhood vaccination programs, primarily in the Third World.
"This change in focus doesn't mean that Bill Gates is any less competitive, just that he has once again redefined the game into one at which he knows he can win. When you are the richest man in the world, nobody can beat you at giving money away."
Slashdot Mirror
This is why I constantly emphasis "in a rotating frame of reference". Yes, the centrifugal force is an artifact of the reference frame, but it greatly simplifies the problem to use the rotating frame and add the centrifugal force.
/. readers have at least a bachelor's degree in physics, so I'm OK with respect to this. :-)
There is nothing wrong with centrifugal force, so long as you clearly understand that it is a mathematical device, rather than physical reality.
I.e. it is not bad physics. It could be accused of being bad pedagogy if your audience doesn't already understand the above. Of course, all
The fact that a mutation of the FOXP2 gene in the "KE" family causes language impedements does not imply that the gene has anything whatsoever to do with language in normal usage.
Here's an analogy. We have a bunch of variations on a model of car. Some have the exhaust pipe on the left, some on the right. Those with the exhaust pipe on the right frequently have failures of the electrical system - because the hot exhaust pipe is too close to some critical part of the electrical system, causing it to burn out.
Now think FOXP2 gene => which side the exhaust pipe goes on, and electrical system => language system.
(This objection is not original with me - it is raised by Stephen Pinker in one of his books, probably The Language Instinct. It might not be original with him either.)
In general, the article in question looks to me like poorly supported speculation - although that may be an artifact of it having been filtered through a science reporter.
I don't understand how they can base it so far from the equator. If you start the counterweight south of the equator, above Perth, it will be way north of the equator 12 hours later.
In more detail:
In a reference frame rotating with the Earth, the counterweight has three forces on it:
Gravity: G m M_earth / r^2
towards the center of the earth
'Centrifugal' force (because we are in a rotating frame): v^2 / r cos l (l = latitude) directed perpendicular to and away from the earth's axis
Tension on the cable.
We want these three forces to cancel out, so that the counterweight is stationary (in the rotating frame.) The problem is that the gravity force has a north/south component unless the counterweight is on the equator. The centrifugal force can't have a north/south component, so the balancing force has to come from the cable tension.
The cable will have be at a small angle to vertical, and the north/south component of the tension is proportional to the sine of this angle, so that component can't be big.
Aha! I think I have the solution.I was thinking of the counterweight being above the tether point.
In the 1st approximation, put the counterweight in geostationary orbit (i.e. on the equator). Run the cable to it.
If the cable had no tension, we would done - but it does. The major component of the tension is towards the earth. We compensate for this by moving the counterweight into a higher orbit. (Decreases gravity, increases centrifugal force, to balance the tension.) There is nothing new here - the Highlift Systems website talks about this.
If the cable was anchored south of the equator, it will have a slight angle to vertical, which will give a southwards force component. If we now modify the orbit of the counterweight to be slightly south of the equator, there will be a northward component to the gravity vector. We can adjust to balance.
From the point of view of the tether point, the cable (if it is straight) will be pointing almost towards the geostationary point. From 30 degrees south, that would be a point about 3000 km north and about 35 km up, so it would be about 5 degrees off vertical.
This smells suspiciously of renaming something old so it seems new.
In the early 1980s, the IRAS satellite did an all-sky survey at wavelengths up to 100 micron - i.e. about 3 THz.
The article says "most current radio technology stops at around 100 GHz." I myself have observed at 345GHz (0.345 THz) using radio astronomy techniques, and this was over 10 years ago. (This was at the Caltech Submillimeter Observatory, but it is not the only such observatory in the world.)
There is some new stuff here, however - at CSO, we had only one pixel, and they are talking about a compact 16 pixel detector (working at 0.2 to 0.3 THz - I.e. much the same frequencies as we were using.)
From an astronomical point of view, although detectors are a fairly big issue, our main problem was noise from the atmosphere - i.e. the atmosphere 'glows' at these wavelenghts, which tends to drown out the astronomical objects you are looking for.
It isn't the difference between cause and effect, it is the difference between proximate cause and ultimate cause.
Would such a script be a 'derivative work' of the movie it was intended to modify?
Is there a copyright lawyer in the house?
If you fitted a grille over the intake of the super water jet engine, you could put out the fire with a more powerfull blast from a more reliable engine and not have any disadvantages like slugging the burning marina with underwater potatoes and sucked up fish.
So you've got fire, fish, potatos and a grill for the potatos to pass through.
Fish and chips?*
* For non-English speakers: chips = french fries.
And of course complex software systems like this never have bugs, and couldn't possibly lock somebody in a room overnight because the system doesn't belive they can be near the only door.
From the article:
... will announce customers including ASP Futuro Bolivia, which uses Linux and Oracle 9i RAC using four, four-processor HP servers to manage the pensions of about half the retirees in Bolivia."
"HP
An interesting point here is that once you've paid for an Oracle 4 proc license, the cost of adding a proprietry Unix likely won't even change your second-most-significant digit in the price. This means these people believe Linux is better than proprietry, independent of the free/gratis factor.
Many fuel cell products/prototypes use a hydrocarbon fuel (I think typically methane or methanol.) They use a 'reformer' to extract the hydrogen from the hydrocarbon, to pass it to the fuel cells.
This gives a number of options to reduce the problem of setting up the hydrogen distribution network:
* Reformer in vehicle. Fuel it with methane (i.e. natural gas - already available on tap in many cities) or methanol (liquid, can use existing petrol/gas station network) or perhaps even ordinary petrol/gas or diesel. (I'm not sure how flexible the reformers are.)
* Reformer at petrol/gas station. It gets the feedstock as above, and provides hydrogen to your car.
* Piped hydrogen (the network you worry about needing to set up.) This can be set up in stages, due to the above options.
Disclaimer: All this is from memory from popular science/technology articles. I don't know how efficient these things are. I do remember that they need to run hot (about 300C I think.)
I'm having troubles deciding whether this post is just plain ignorant, or whether it is a subtle parody of the music/napster/copyright/RIAA debate.
Almost all scientific journals charge the researcher money to publish in them. This money is paid from the grant that supported the research activity.
Like almost anyone, academics like to be well paid, but it isn't journal subscriptions that pays any part of their salary.
My first thought on seeing this article was "Hey, somebody's slashdotted the Aardvark!"
/., the Aardvark is one of my visit-every-day sites. Of course, non-New Zealanders will find the site less interesting.)
Then I looked again at who submitted it - the Aardvark slashdotted the Aardvark!
Are you stress testing your web server, Bruce?
(Along with a few comic strips and
On the other hand, there are definate failures of peer-review. I am a co-author on a paper that refuted another paper. The original paper should never have passed peer review. The most egregious error was that the energy of a collision was underestimated by something like 12 orders of magnitude. It appears that the error was both arithmetic (failure to convert all quantities to SI units before multiplying) and physical (failure to account for gravitational potential energy.)
Come on, this is a "Score:3 Funny" not a "Score:5 Funny."
I see someone had the sense to put an 'overrated' on it, but evidently someone else undid the good work.
Hm, going off on a tangent in a big way:
A man was holding a very small dinner party, with his father's brother-in-law, his brother's father-in-law, his father-in-law's brother and his brother-in-law's father.
How small can the party be?
(This puzzle comes from the Rev Charles Dodgeson, the famous Victorian photographer, mathemetician and author. As the puzzle is of English origin, first cousins may marry.)
An extension *not* from the Rev Dodgeson: How much smaller can the party become if we ignore incest marrage restrictions? What is the least relaxation on the incest laws to allow this minimum size?
I'm confused. I know what a founder co-founder is (one of the parents of the founder), but what is a co-founder founder? The original from which the co-founder was cloned?
The problem you describe is not "radio broadcast vs optical narrow beam", it is "broadcast vs narrow beam". Once I've decided to go narrow beam for these reasons, why would I go optical rather than microwave?
(The beam divergence is inversely proportional to the number of wavelengths wide your transmitter/reflector is, which means that smaller wavelength requires a smaller transmitter apperature to achieve a given beam divergence, but surely microwaves are good enough, and have much better penetration.)
Very little. 1500 mJ, specificaly. It's done every day.
That is a measure of energy, not of power.
Uhhh... only if you're in the visible light spectrum. Some wavelengths will pass right through clouds (and other objects, like the earth) completely unphased.
Some wavelengths are less affected by cloud than others - I'm *guessing* about 10 microns would be a reasonable compromise between cloud penetration and water vapour (as opposed to droplets) interference.
However, NO wavelength of light will pass through the earth (although you can get some penetration through a few km of ice.) Do you know the difference between a photon and a neutrino?
Here's a quarter, kid. Go buy a clue.
I think you need all your quarters. If you're going to be arrogant, you need to make sure you are also right.
Oh, for a room with a view of the sign, a tunable Gunn oscillator, and a reflector to beam my signal at the sign.
Hours of fun, convincing the sign that everybody leaving the football game is listening to a PBS classical music station.
For more fun and games with Gunn oscillators, see also trolling for taillights.
When I was in the final stages of writing my thesis, I had backups on ZIP disks:
One set in the same room as my computer - generally a day or two old.
One set in another room in the house - a bit older.
One set in another house in the same city.
One set (a few weeks old) in my brother's house about 500 km away.
This gave me a good lifeline to sanity when I accidentally deleted my partition table a week before finishing. (In fact, I didn't need the backup - I had the partition table info in hardcopy and just reentered it.)
Now I use my computer mostly for games, so my only backup is that my parents have copies of all my photos.
"Paranoia is good".
Mira is 'wonderful' or 'astonishing' in Latin. The first variable star discovered is named Mira. It is about 3rd magnitude at brightest, and invisible to the naked eye at other times.
I don't know if the Latin word or the star had any part in Microsoft's naming.
Dr Skeptic is wondering how you know all this.
Have you seen the statutes yourself, and confirmed they are still current?
Have you personally spoken to a lawyer who has confirmed the statements?
Have you simply repeated these statements as true, after seeing them made by someone of unknown trustworthiness and knowledge?
Inevitably, IANAL, but I'm going to express my uninformed opinion anyhow. (What else is /. for?)
I really don't think this will fly. Just because you've spent money on something, it doesn't mean that nobody else is allowed to do anything that will adversly affect your investment. You may just have made a bad investment.
E.g.: I buy an island and build a luxury resort specifically for celebrities to get away from paparazi. Once I open it, the paparazi start hanging out in boats off shore (a public area). I can't make them go away.
E.g. 2: I build a luxury apartment block next to an airport. I can't sue the airport to reduce noise just because I can't sell my apartments.
E.g. 3: I distribute movies on a medium that allows me to prevent people skipping the ads. Someone starts distributing programs that will play my movies while allowing the ads to be skipped. I can't sue them simply because this has an adverse effect on my advertising income.
E.g. 4: I spend lots of money building up a buggy-whip business...
O.K, looking back at this list, you *shouldn't* be able to sue in these cases.
Reread my post. All I said was that the 'that many people can't keep a secret' argument is weaker than it first appears.
Incidentally, the F-117's existence was not a well kept secret, although the details were. There was even a plastic kitset 'stealth fighter' model sold before the F-117 was unveiled - but it bore little resemblence to the actual plane.
I don't believe these nutcases. However, I recently realized that one of my arguments against them is not as strong as I thought.
Here's the argument: Tens of thousands of people were involved in the Apollo program. There were thousands of them who would unavoidably know if the moon landings were faked. Several thousand people can't keep a secret for over 30 years.
What is wrong with this argument? Bletchley Park. For about 30 years, several thousand people kept the secret that the allies hand broken most of the axis codes during World War II.
(It is still a valid argument, however - there are differences between Bletchley Park and a hypothetically faked Apollo 11.)
Robert Cringley had an interesting take on this in one of his old weekly columns.
... And if he can't win, then he'd rather not play." ...
"The single most driving force in the development of Bill Gates today or any day is his competitive nature. The guy simply has to win, and will do pretty much whatever it takes to succeed.
"The Bill and Melinda Gates Foundation has committed $750 million to childhood vaccination programs, primarily in the Third World.
"This change in focus doesn't mean that Bill Gates is any less competitive, just that he has once again redefined the game into one at which he knows he can win. When you are the richest man in the world, nobody can beat you at giving money away."