actually, 99% of nanotechnological research entails projects like this (or similar w/ dna or other self-assembling systems). It's primarily only in the popular media and sci-fi/fear mongering sites/papers where you hear about nanobots crawling around inside your body.
I don't take it so much as Stewart informing people, but instead that the 'smarter' people prefer the Daily Show over the other dribble. My girlfriend and I are about to get cable tv (or satellite), and Daily Show is one of the main reasons we want to get it.
Daily Show is not dumbed down, it doesn't have laugh tracks to let you know where the jokes are, it makes you think, and is hysterical to boot. If you don't get the jokes or need someone to tell you who's the 'bad' and 'good' guy you watch O'Reilly, not Daily Show. If you like good satire and good jokes, some subtle some much less so, and funny commentary on the state of affairs in the USA and the world, you watch the Daily Show.
Re-usable modules anybody?? Heard of those? Standard designs?
I hate to tell you this, but NASA HAS been using proven parts in spacecraft, there is a strong push for COTS (Commercial Off-The-Shelf) Hardware, it's much cheaper than designing every op-amp from scratch. But this COTS stuff has to be beyond military spec, it has to be rad-hard, withstand severe thermal and vibrational stresses, etc. It's easy to make a reusable op-amp or logic gate in a desktop computer, but for a satellite they have to be MUCH more rugged.
Regarding this accelerometer, not sure why it had to be different, but like I said before, it definitely needed to be rad-hard, endure strong vibrational and thermal extremes, and still function flawlessly upon re-entry. That's not easy to design, and there are 100000000 things to go wrong, one of which is that it's installed backward.
Now as to the reason they don't re-use spacecraft designs is that every craft has different operating parameters. Some are very far from Sun and Earth, and need higher-gain antennas (ie, parabolic dishes that can retract) and RTG's (solar panels become inefficient beyond Jupiter). Some operate close to Earth orbit and use solar panels and smaller antennas. Some will never re-enter earth, some will burn up on re-entry when their use is finished, and some need to survive re-entry intact. Some craft close to the sun (eg SOHO) need special rad-hard thermally-shielding designs. The inclusion or exclusion of each of these items will drastically change the structure of the craft.
So basically, each mission is so different that it's very unfeasible to come up with a reusable 'strawman' design from which to start all NASA craft. And this is just considering operating environment, power, and communications. That's not even including the scientific instruments, all of which need specialized heating or cooling or shielding or vibrational-isolation requirements, etc.
These airships are peanuts compared to what industry uses (cryogenics, for instance). Not just that, but remember the pressure of the atmosphere at these altitudes is so low that the giant volume of the airships would be considerably smaller at sea level. Hence, much less helium would be used than you'd expect. About 10 years ago I worked on a balloon project with NASA, and when we launched the balloon didn't even look like it had much helium at all in it, but it sure lifted off pretty fast (went about 20 miles high).
You're right that helium escapes into space, at the surface temperature of the Earth, helium atoms have escape velocity (or close enough to it, accounting for the Maxwellian velocity distribution). So unearthed helium eventually escapes away from the planet. Hydrogen does as well, but I believe all other gases are heavy enough to remain bound.
I work in cryogenics here in the USA, and we routinely let helium gas escape into the air (eg, when inserting a room-temperature insert into a dewar of liquid helium). In Europe, from what I understand, most labs collect this boiled-off helium gas, and somewhere else they can re-liquefy it. Don't know what Canada, South America, Asia, or other places do, though.
One of my professors was explaining why we don't recycle the helium here in the USA. He said this is because helium is typically 'mined' at the same time as companies dig for oil and natural gas. Thats where the large helium deposits are found. The market for helium is so small that petroleum companies want to just let the helium gas escape, it's not worth their time to collect/purify/sell it.
The NSF, however, doesn't want this to happen (environmental issues and maybe to capture more of the rare He3 too), and was able to influence American-based petrol companies to collect and sell the helium instead of wasting it. In exchange the oil companies need to have enough of a helium market to do this, so that's why Helium gas is typically not recycled in the USA, so the oil companies will sell it instead of let it go.
As one side note - you need to use alot of He gas to make recycling it cost effective, so only a few institutions in the USA recycle He. In Europe the density of such labs is much higher, so it's easier for Europeans to recycle this. Not sure if He is recycled in South America or Asia, though.
So unless my professor is entirely bullshitting, the problem stems not only from many labs not recycling He, but from global petrol companies letting the He gas free instead of capturing it themselves. But as to your original question, there shouldn't be significant amounts of helium used in the airships compared to global supply.
Actually, I've long wondered why we can't produce paper in a lab, instead of chopping down trees. As far as I know, wood pulp is mostly cellulose, and with some other binding agents, most of that we should be able to produce artificially. Anybody know of any reason why this isn't done, or perhaps isn't feasible?
One guess might be that it's easier to let trees grow on their own, instead of having a lab pump energy into a vat to grow the cellulose.
In the summer of 2000 I used a program called Garble to talk to my GPS (Garmin GPS II+), its Freshmeat page looks like it hasn't been updated since almost that time. I vaguely remember talking to the author shortly after the summer and (s)he was too busy and was dropping the project (I could be wrong). This program worked perfectly with my GPS, but it read lat/long data from the serial port. I don't know how hard it would be to hack this program to use the USB port instead.
I used Garble because back in Summer 2000, before the grueling years of my physics PhD program began, I took a 15,000 mile roadtrip around the USA. During most of the driving I had my laptop connected to my GPS, pinging it every minute (through a simple bash script) getting a latitude and longitude. After my trip I compiled all the points, and used IDL to make some nice plots from the data. IDL was cool because I could easily set up map projections w/ my latitude/longitude data, overlap satellite images, and even plot country/state borders (IDL costs $$$$$, but Johns Hopkins University physics department has a large client license on the student terminals, which is nice). Check out my final Mercator Plot and Satellite Perspective Plot. My route is in red (chronologically going clockwise around the country), yellow circles are where I spent the night.
You can read my unfinished online journal here. Yeah, it's been a few years since the trip, and I do really need to finish that journal and clean up the ugly page layouts.
Actually, if you look at the microscopic physics, they both use the same forces. It's primarily electromagnetic forces, although some quantum degeneracy statistics plays a role too, that prevent your hand from going through a door when you knock on it. However, in fluidics (and sound) phonons are being transmitted through the medium, just like photons are transmitted through the wires in electronic systems. However, the sound waves derive mostly from the usually harmonic potentials keeping molecules spaced apart at their average distances. EM waves derive from charges (ie, electrons) moving and reacting with each other.
This also implies that fluidic computing will always be slower than electronics
Practically yes, but to be pedantic - not necessarily always. Maxmimum signal speed in fluidics would by governed by phonons, and in electronics by photons.
In reality the phonon modes, which are usually pretty dispersive (ie propogation speed depends on frequency), have slower propagation speeds than photons (also usually dispersive but usually not as much) in most matter.
But to say 'always' isn't necessarily true, there's no reason a priori to assume in some random material photonic excitations are necessarily faster than phononic excitations.
You, sir, are a moron. They didn't invent a new mechanism for transmitting a signal. Electrons _have_ to be used.
This seems to be a common misperception on slashdot.
Electrons are certainly used, of course, in digital logic circuits. For example representing bits as charge stored in a capacitor, or by mediating the quantum statistics of a transistor for switching (by controlling the charge on the gate of a MOSFET).
However - when a signal is sent down a wire (eg, from a microprocessor, over the data bus, to a peripheral) that signal is NOT being sent through the electron drift. [Although electrons will drift in presence of an electric field, the drift velocity is INCREDIBLY small, look it up.]
If the microprocessor wants to flip a bit from a 0 to a 1, the wire is originally at one potential, and the microprocessor will change the potential. This disturbance isn't instantaneous along the wire, that would violate relativity. The microprocessor basically creates an electromagnetic disturbance that travels down the wire to the peripheral.
Now let's look at this 'disturbance' more closely. Electrons at point A are being ultimately effected by electrons at point B. This effect is mediated through electron interactions, and one knows that that the electromagnetic force is the mediator between electrons. And from Quantum Field Theory one knows that photons are the quanta of the electromagnetic force.
So what this in effect means is that whenever electrons are interacting, photons are being transmitted somewhere during that exchange. Thus, the parent was correct that it's the electromagnetic wave, as opposed to the physical motion of the electrons themselves. that plays the role in limiting digital logic speed.
Speed of light in vacuum, c, will always be faster than the speed of propogation of any particle, mode, or disturbance**.
The speed of light in a material is slower than in a vacuum, by a factor of the index of refraction (usually frequency dependent). Interestingly, it IS possible for particles to travel faster than this apparent speed of light, and in doing so they emit Cerenkov Radation, which is how many high-energy physics particle detectors (eg SNO) detect individual particles.
** For the nitpickers who will inevitably respond to that generalization, it is occasionally possible (in theory, at least) to set up a mode in some carefully-devised system where the speed of propogation of this mode is faster than c, but this mode cannot carry information. Simple example is a linear array of equally-spaced pendula, each with the same fundamental frequency, and with a spring connecting the weights at the bottom to the two pendula on either side. If a mode is set up where all pendula are oscillating at their fundamental frequency, all of them at exactly the same phase, (springs always remain at their unstretched length) then the phase velocity of this mode is infinite. However, there can be no 'information' or disturbance transmitted down the system. In reality, thermal and quantum disturbances would disrupt this mode and it would eventually become something much more complicated. These disturbances would be transmitted at a finite velocity, less than c.
Practical uses? Well, for starters, it's microfluidics. So if we're lucky, we'll finally be able to get one of these babies into a package small enough to fit in a watch. You've always wanted a digital watch, right?
It's amusing, but in 1967 this Fluidic Amplifier was billed as "the simplest device known for setting up digital circuit applications."
There was no conflict before the Zionists began their plans to remove Arabs from Israel.
I shouldn't feed the trolls, but you should look up the riots of Hebron in 1929, makes the Israeli Jenin attack from a few years ago, or the current Gaza incursions, look pale in comparison.
It will be interesting to see how well this telescope will work on long-time integration imaging.
That's another area where Hubble excels because it can integrate an area of sky for several orbits (Hubble Deep Field, for example), picking out very faint galaxies from nearly individual photons. These ground-based scopes, while integrating for long times, will probably integrate more scattered atmospheric light, and not be able to extract faint galactic signals from atmospheric noise nearly as well as Hubble.
No. The Zionists attacked the Arab Israelis (soon to be renamed "Palestinians") in 1948. They started it.
Sigh, people like you are just not worth trying to reason with. You'll never get it through your skull that Palestinian and Arab agression has some part to play in the history of the conflict. You only want to blame "Zionists" as sole instigators of the conflict. Luckily most other adamantly anti-Israeli folks are much more reasonable.
You say "That [Zionists] started it". I'll leave you with three quotes. First, from the UN security council on Feb. 16, 1948 :
Powerful Arab interests, both inside and outside Palestine, are defying the resolution of the General Assembly and are engaged in a deliberate effort to alter by force the settlement envisaged therein.
The Arab High Committee spokesmen to the UN, Jamal Husseni, announced to the UN security council on April 16, 1948 :
The representative of the Jewish Agency told us yesterday that they were not the attackers, that the Arabs had begun the fighting. We did not deny this. We told the whole world that we were going to fight.
And finally, Azzam Pasha, the secretary-general for the Arab League declared on May 14, shortly before the five armies of Egypt, Syria, Transjordan, Lebanon, and Iraq invaded Israel :
This will be a war of extermination and a momentous massacre which will be spoken of like the Mongolian massacres and the Crusades.
But I doubt you'll ever be convinced that any blame of the conflict should fall on any Arabs, it's much easier to just blame "the Zionists".
Compare it with North America in 1771. Was it right for the British Empire to control those people without allowing them to vote, just hanging it on "Oh, they don't live in Britian, just in a land totally under our military and economic control?"
Huh? The colonists never attacked the English before they moved to the New World. Israel was attacked by Palestinians (and Egyptians, Jordanians, Syrians, etc) before the occupation. Your analogy makes no sense.
You try to sway the argument by using vernacular like 'conquer'. Israel 'captured' the land in a war it didn't start. Its offers to return the land immediately after the war in exchange for peace were absolutely refused by all Arab nations.
What was Israel supposed to do at this point?
You initially implied Israel is an apartheid country by not letting Arabs vote, I proved you wrong, and now you're changing the semantics to try to demonize Israel again.
Every Arab living in Israel can vote in every Israeli election. Every Israeli citizen can vote in every Israeli election, for that matter. The settlers are basically Israeli citizens living 'abroad' (and before you go and accuse me, I don't agree w/ the occupation).
Jewish settlers can't vote in Palestinian elections, Palestinians can't vote in Israeli elections.
But anyway, as you say "same tired old objections to wind power", that implies people have brought up this concern long before me.
Sure they have. Read any random front page article on Slashdot on wind power.
If slashdotters keep bringing it up (and I've certainly brought it up before), then surely someone somewhere must have brought the issue up to a respected climatologist sometime.
You will notice that there are no scientific studies showing that there is no significant harm to humanity if an asteroid strikes the moon
Yes, there have been, actually. And Monte-Carlo simulations too. And they've demonstrated that moons can sometimes 'protect' a planet by diverting the asteroid (Shoemaker-Levy comet, for example).
It's ironic (and pathetic too) that most people responding to your post only care about Israeli atrocities. Nobody here even seems to give a shit about Sudan, where around 50,000 people have been killed by the Janjaweed militias in the past few years, and atrocities are still occuring daily. A few thousand are expected to die every few weeks due to starvation and malnutrition.
Why are Palestinians worth so much more than Sudanese?
Actually you bring up a good point. The parent said
"it's original borders, as mandated by the UN and defined at the time of its creation" which is a much smaller piece of land then the 'green line'.
Ie, UN gave Israel only a tiny piece of land, and after the Arab neighboring armies attacked and Israel miraculously defended itself (in spite of lack of UN intervention and even a British arms embargo on Israel) more land was taken.
It's interesting because I do think that once Israel withdraws back to the green line, the Arab League will start pressuring the world to make it withdraw back to the original UN partition plan line, before the War of Independence.
Once again I'll put my karma on the line and go against some of the rampant anti-Israel FUD being tossed around here. Before the hordes respond to me please understand I do NOT support the Israeli occupation, but that doesn't mean I'll let unsubstianted FUD get tossed around easily.
(a) Israel is building a big fuckoff wall *way outside* those borders, conveniently annexing large swathes of territory that do not belong to Israel with NO JUSTIFICATION
The first part I can't argue much with, but there IS justification. Namely that the wall between Israel and Gaza has worked quite well, and the parts of the wall between Israel and West Bank thus far completed have cut down on attacks.
If you want to get into the mindset of many Israelis, not just the right wingers, they consider taking extra land as the lesser of two evils than deaths of terror attacks and Israeli reprisals. Do you actually consider land more important than life?
At this point people claim "just end the occupation and the terror will stop", but before there was any occupation, the terror existed. The Palestinian LIBERATION Organization formed before Israel captured Gaza and West Bank, those parts were OCCUPIED by Egypt and Jordan respectively. What part of Palestine was Arafat and company trying to liberate?
(b) Israel is pursuing a systematic policy of colonising a foreign territory with 'native' Israelis
Well, if you know what happened at the end of the Six Day War, Israel offered to return ALL occupied territories back to their owners. The Arabs collectively refused with the famous Three No's (No Recognition, No Talks, No Peace). What the hell was Israel supposed to do at that point? Say "Well, take your strategic land back then and by all means keep attacking us."?
Now I do agree with you that during Oslo Israel didn't fulfill it's requirement to remove settlements, but neither did the Palestinians meet their requirements to end the incitement and arrest known terrorist leaders. Some minor terrorists were arrested, but usually released (as the saying goes, put into Palestinian jails with revolving doors).
(c) Israelis forces are performing violent operations against civilian, terrorist and militia forces alike with no real concern as to which is which, outside its own territory, with no international sanction and indeed against international law and consensus
Well, if you look at the past few decades, they kept trying to get Arafat and the PA to do these on their own. They refused. Even just days after the most recent intifada broke out, Arafat released hundreds of known terrorists out of jail. This was long before Israel started destroying Palestinian jails and other infrastructure.
The PA refuses to do anything. Many attacks, both before and after the intifada, were carried out by Palestinian policemen, many were trained and/or armed by Israel as part of Oslo.
PA does nothing to stop this, except issue mild rebukes IN ENGLISH to the media.
(d) the Israeli government actually talks about maintaining the genetic purity of Israel (ah the irony) in the sense of making sure that at least 50% of Israelis are Jewish so that there can never be a 'democratic coup' inside Israel at election time
You're misleading people here, whether intentionally or not. Firstly, of course Israel wants to be a Jewish nation, that was the point of its creation. Remember the UN partition plan also called for no Jews to be allowed in Jordan, and in fact Jews are specifically barred from becoming citizens there. Same thing with other Arab countries, Jews are inferior or forbidden from becoming citizens. So if you criticize Israel, at least criticize the rest of the Arab Leage too.
And as far as being a Jewish nation, given treatment of Jews through history (Obviously Holocaust, but also pograms in Russia, Inquisition in Spain, being inferior dhimmis in Arab lands, etc) the point of Israel is to create an outl
I would imagine that you were modded down for rehashing the same tired old objections to wind power.
I've come up with that argument myself a few years ago, I've never heard anyone else bring it up. Perhaps the silence of established climatologists speaks of the validity of the argument.
But anyway, as you say "same tired old objections to wind power", that implies people have brought up this concern long before me. And if so then the wind-power people and/or climatologists should have well-reasoned scientific explanations to easily refute it. Do you know of any such refutation?
while your concern is fine to ponder as an academic exercise it really doesn't have the kind of grounding in reality that I would want it to go unchecked in this public forum.
Oh, I agree with you. I was bringing it up as a possible side effect of massive wind harvesting. I'm not running around claiming the sky is falling w/ wind power, it's just something I've pondered (actually while sailing past a number of windmills). And it's something that I haven't seen anybody bring up before.
I think the physics of my argument makes sense, the question is in terms of the scale of the energy involved. I'm certainly not insightful enough to get this order-of-magnitude estimate from what little I know about climatology. But it seems you agree, at least somewhat, on my hypotheses. Neither of us know the relavent scale of possible climate change (maybe femto-degrees celcius, maybe more), but that's fine.
At least I presented a somewhat defined argument, though. My area of research verges on nanotech, and every time nanotech is brought up on slashdot people run around with doomsday grey-goo scenarios. Yet not one of these people has presented a valid biochemical theory of how this would work. It's just rampant fear-mongering of something they don't understand, kind of like radioactivity in the 40's and 50's [pop culture example : spiderman was originally bit by a radioactive spider in the comics, in the movie he was bit by a genetically-modified spider].
it seems to be standing policy by each new president to pardon the previous president, as each wants the same from the following president.
Actually, Bush never pardoned Clinton, he said he had no intention of doing that. So interestingly enough, Bush may have set himself up for his successor to specifically not pardon him.
Cool, that was refreshing to read this post. Someone else mentioned the fact that wind flows up to many km while the windmills are only several hundred meters max. So while one 'wall' of windmills (spread out on a line orthogonal to the direction of the wind) might be not noticeable, but after several successive such 'walls' of windmills the air above will become somewhat more rarified and slow down. Dunno how many such walls it would take.
Anyway, it would be an interesting, perhaps useful, topic for the climatologists to study.
So back in your first post you said at the end "Wass even claims an undergrad degree in physics. He really should know better." Just for purposes of closure and/or beating a dead horse, do you still feel that way?
Slashdot Mirror
actually, 99% of nanotechnological research entails projects like this (or similar w/ dna or other self-assembling systems). It's primarily only in the popular media and sci-fi/fear mongering sites/papers where you hear about nanobots crawling around inside your body.
Daily Show is not dumbed down, it doesn't have laugh tracks to let you know where the jokes are, it makes you think, and is hysterical to boot. If you don't get the jokes or need someone to tell you who's the 'bad' and 'good' guy you watch O'Reilly, not Daily Show. If you like good satire and good jokes, some subtle some much less so, and funny commentary on the state of affairs in the USA and the world, you watch the Daily Show.
I hate to tell you this, but NASA HAS been using proven parts in spacecraft, there is a strong push for COTS (Commercial Off-The-Shelf) Hardware, it's much cheaper than designing every op-amp from scratch. But this COTS stuff has to be beyond military spec, it has to be rad-hard, withstand severe thermal and vibrational stresses, etc. It's easy to make a reusable op-amp or logic gate in a desktop computer, but for a satellite they have to be MUCH more rugged.
Regarding this accelerometer, not sure why it had to be different, but like I said before, it definitely needed to be rad-hard, endure strong vibrational and thermal extremes, and still function flawlessly upon re-entry. That's not easy to design, and there are 100000000 things to go wrong, one of which is that it's installed backward.
Now as to the reason they don't re-use spacecraft designs is that every craft has different operating parameters. Some are very far from Sun and Earth, and need higher-gain antennas (ie, parabolic dishes that can retract) and RTG's (solar panels become inefficient beyond Jupiter). Some operate close to Earth orbit and use solar panels and smaller antennas. Some will never re-enter earth, some will burn up on re-entry when their use is finished, and some need to survive re-entry intact. Some craft close to the sun (eg SOHO) need special rad-hard thermally-shielding designs. The inclusion or exclusion of each of these items will drastically change the structure of the craft.
So basically, each mission is so different that it's very unfeasible to come up with a reusable 'strawman' design from which to start all NASA craft. And this is just considering operating environment, power, and communications. That's not even including the scientific instruments, all of which need specialized heating or cooling or shielding or vibrational-isolation requirements, etc.
You're right that helium escapes into space, at the surface temperature of the Earth, helium atoms have escape velocity (or close enough to it, accounting for the Maxwellian velocity distribution). So unearthed helium eventually escapes away from the planet. Hydrogen does as well, but I believe all other gases are heavy enough to remain bound.
I work in cryogenics here in the USA, and we routinely let helium gas escape into the air (eg, when inserting a room-temperature insert into a dewar of liquid helium). In Europe, from what I understand, most labs collect this boiled-off helium gas, and somewhere else they can re-liquefy it. Don't know what Canada, South America, Asia, or other places do, though.
One of my professors was explaining why we don't recycle the helium here in the USA. He said this is because helium is typically 'mined' at the same time as companies dig for oil and natural gas. Thats where the large helium deposits are found. The market for helium is so small that petroleum companies want to just let the helium gas escape, it's not worth their time to collect/purify/sell it.
The NSF, however, doesn't want this to happen (environmental issues and maybe to capture more of the rare He3 too), and was able to influence American-based petrol companies to collect and sell the helium instead of wasting it. In exchange the oil companies need to have enough of a helium market to do this, so that's why Helium gas is typically not recycled in the USA, so the oil companies will sell it instead of let it go.
As one side note - you need to use alot of He gas to make recycling it cost effective, so only a few institutions in the USA recycle He. In Europe the density of such labs is much higher, so it's easier for Europeans to recycle this. Not sure if He is recycled in South America or Asia, though.
So unless my professor is entirely bullshitting, the problem stems not only from many labs not recycling He, but from global petrol companies letting the He gas free instead of capturing it themselves. But as to your original question, there shouldn't be significant amounts of helium used in the airships compared to global supply.
One guess might be that it's easier to let trees grow on their own, instead of having a lab pump energy into a vat to grow the cellulose.
I used Garble because back in Summer 2000, before the grueling years of my physics PhD program began, I took a 15,000 mile roadtrip around the USA. During most of the driving I had my laptop connected to my GPS, pinging it every minute (through a simple bash script) getting a latitude and longitude. After my trip I compiled all the points, and used IDL to make some nice plots from the data. IDL was cool because I could easily set up map projections w/ my latitude/longitude data, overlap satellite images, and even plot country/state borders (IDL costs $$$$$, but Johns Hopkins University physics department has a large client license on the student terminals, which is nice). Check out my final Mercator Plot and Satellite Perspective Plot. My route is in red (chronologically going clockwise around the country), yellow circles are where I spent the night.
You can read my unfinished online journal here. Yeah, it's been a few years since the trip, and I do really need to finish that journal and clean up the ugly page layouts.
Actually, if you look at the microscopic physics, they both use the same forces. It's primarily electromagnetic forces, although some quantum degeneracy statistics plays a role too, that prevent your hand from going through a door when you knock on it. However, in fluidics (and sound) phonons are being transmitted through the medium, just like photons are transmitted through the wires in electronic systems. However, the sound waves derive mostly from the usually harmonic potentials keeping molecules spaced apart at their average distances. EM waves derive from charges (ie, electrons) moving and reacting with each other.
This also implies that fluidic computing will always be slower than electronics
Practically yes, but to be pedantic - not necessarily always. Maxmimum signal speed in fluidics would by governed by phonons, and in electronics by photons.
In reality the phonon modes, which are usually pretty dispersive (ie propogation speed depends on frequency), have slower propagation speeds than photons (also usually dispersive but usually not as much) in most matter.
But to say 'always' isn't necessarily true, there's no reason a priori to assume in some random material photonic excitations are necessarily faster than phononic excitations.
This seems to be a common misperception on slashdot.
Electrons are certainly used, of course, in digital logic circuits. For example representing bits as charge stored in a capacitor, or by mediating the quantum statistics of a transistor for switching (by controlling the charge on the gate of a MOSFET).
However - when a signal is sent down a wire (eg, from a microprocessor, over the data bus, to a peripheral) that signal is NOT being sent through the electron drift. [Although electrons will drift in presence of an electric field, the drift velocity is INCREDIBLY small, look it up.]
If the microprocessor wants to flip a bit from a 0 to a 1, the wire is originally at one potential, and the microprocessor will change the potential. This disturbance isn't instantaneous along the wire, that would violate relativity. The microprocessor basically creates an electromagnetic disturbance that travels down the wire to the peripheral.
Now let's look at this 'disturbance' more closely. Electrons at point A are being ultimately effected by electrons at point B. This effect is mediated through electron interactions, and one knows that that the electromagnetic force is the mediator between electrons. And from Quantum Field Theory one knows that photons are the quanta of the electromagnetic force.
So what this in effect means is that whenever electrons are interacting, photons are being transmitted somewhere during that exchange. Thus, the parent was correct that it's the electromagnetic wave, as opposed to the physical motion of the electrons themselves. that plays the role in limiting digital logic speed.
The speed of light in a material is slower than in a vacuum, by a factor of the index of refraction (usually frequency dependent). Interestingly, it IS possible for particles to travel faster than this apparent speed of light, and in doing so they emit Cerenkov Radation, which is how many high-energy physics particle detectors (eg SNO) detect individual particles.
** For the nitpickers who will inevitably respond to that generalization, it is occasionally possible (in theory, at least) to set up a mode in some carefully-devised system where the speed of propogation of this mode is faster than c, but this mode cannot carry information. Simple example is a linear array of equally-spaced pendula, each with the same fundamental frequency, and with a spring connecting the weights at the bottom to the two pendula on either side. If a mode is set up where all pendula are oscillating at their fundamental frequency, all of them at exactly the same phase, (springs always remain at their unstretched length) then the phase velocity of this mode is infinite. However, there can be no 'information' or disturbance transmitted down the system. In reality, thermal and quantum disturbances would disrupt this mode and it would eventually become something much more complicated. These disturbances would be transmitted at a finite velocity, less than c.
It's amusing, but in 1967 this Fluidic Amplifier was billed as "the simplest device known for setting up digital circuit applications."
I shouldn't feed the trolls, but you should look up the riots of Hebron in 1929, makes the Israeli Jenin attack from a few years ago, or the current Gaza incursions, look pale in comparison.
That's another area where Hubble excels because it can integrate an area of sky for several orbits (Hubble Deep Field, for example), picking out very faint galaxies from nearly individual photons. These ground-based scopes, while integrating for long times, will probably integrate more scattered atmospheric light, and not be able to extract faint galactic signals from atmospheric noise nearly as well as Hubble.
Sigh, people like you are just not worth trying to reason with. You'll never get it through your skull that Palestinian and Arab agression has some part to play in the history of the conflict. You only want to blame "Zionists" as sole instigators of the conflict. Luckily most other adamantly anti-Israeli folks are much more reasonable.
You say "That [Zionists] started it". I'll leave you with three quotes. First, from the UN security council on Feb. 16, 1948 :
The Arab High Committee spokesmen to the UN, Jamal Husseni, announced to the UN security council on April 16, 1948 :And finally, Azzam Pasha, the secretary-general for the Arab League declared on May 14, shortly before the five armies of Egypt, Syria, Transjordan, Lebanon, and Iraq invaded Israel :
But I doubt you'll ever be convinced that any blame of the conflict should fall on any Arabs, it's much easier to just blame "the Zionists".
Good night.
Huh? The colonists never attacked the English before they moved to the New World. Israel was attacked by Palestinians (and Egyptians, Jordanians, Syrians, etc) before the occupation. Your analogy makes no sense.
You try to sway the argument by using vernacular like 'conquer'. Israel 'captured' the land in a war it didn't start. Its offers to return the land immediately after the war in exchange for peace were absolutely refused by all Arab nations. What was Israel supposed to do at this point?
Every Arab living in Israel can vote in every Israeli election. Every Israeli citizen can vote in every Israeli election, for that matter. The settlers are basically Israeli citizens living 'abroad' (and before you go and accuse me, I don't agree w/ the occupation).
Jewish settlers can't vote in Palestinian elections, Palestinians can't vote in Israeli elections.
Sure they have. Read any random front page article on Slashdot on wind power.
If slashdotters keep bringing it up (and I've certainly brought it up before), then surely someone somewhere must have brought the issue up to a respected climatologist sometime.
You will notice that there are no scientific studies showing that there is no significant harm to humanity if an asteroid strikes the moon
Yes, there have been, actually. And Monte-Carlo simulations too. And they've demonstrated that moons can sometimes 'protect' a planet by diverting the asteroid (Shoemaker-Levy comet, for example).
Why are Palestinians worth so much more than Sudanese?
Ie, UN gave Israel only a tiny piece of land, and after the Arab neighboring armies attacked and Israel miraculously defended itself (in spite of lack of UN intervention and even a British arms embargo on Israel) more land was taken.
It's interesting because I do think that once Israel withdraws back to the green line, the Arab League will start pressuring the world to make it withdraw back to the original UN partition plan line, before the War of Independence.
Newsflash to you - Arabs can vote in Israel. There are even several Arab officials elected to the Knesset (ie, the Israeli parliament).
(a) Israel is building a big fuckoff wall *way outside* those borders, conveniently annexing large swathes of territory that do not belong to Israel with NO JUSTIFICATION
The first part I can't argue much with, but there IS justification. Namely that the wall between Israel and Gaza has worked quite well, and the parts of the wall between Israel and West Bank thus far completed have cut down on attacks.
If you want to get into the mindset of many Israelis, not just the right wingers, they consider taking extra land as the lesser of two evils than deaths of terror attacks and Israeli reprisals. Do you actually consider land more important than life?
At this point people claim "just end the occupation and the terror will stop", but before there was any occupation, the terror existed. The Palestinian LIBERATION Organization formed before Israel captured Gaza and West Bank, those parts were OCCUPIED by Egypt and Jordan respectively. What part of Palestine was Arafat and company trying to liberate?
(b) Israel is pursuing a systematic policy of colonising a foreign territory with 'native' Israelis
Well, if you know what happened at the end of the Six Day War, Israel offered to return ALL occupied territories back to their owners. The Arabs collectively refused with the famous Three No's (No Recognition, No Talks, No Peace). What the hell was Israel supposed to do at that point? Say "Well, take your strategic land back then and by all means keep attacking us."?
Now I do agree with you that during Oslo Israel didn't fulfill it's requirement to remove settlements, but neither did the Palestinians meet their requirements to end the incitement and arrest known terrorist leaders. Some minor terrorists were arrested, but usually released (as the saying goes, put into Palestinian jails with revolving doors).
(c) Israelis forces are performing violent operations against civilian, terrorist and militia forces alike with no real concern as to which is which, outside its own territory, with no international sanction and indeed against international law and consensus
Well, if you look at the past few decades, they kept trying to get Arafat and the PA to do these on their own. They refused. Even just days after the most recent intifada broke out, Arafat released hundreds of known terrorists out of jail. This was long before Israel started destroying Palestinian jails and other infrastructure.
The PA refuses to do anything. Many attacks, both before and after the intifada, were carried out by Palestinian policemen, many were trained and/or armed by Israel as part of Oslo.
PA does nothing to stop this, except issue mild rebukes IN ENGLISH to the media.
(d) the Israeli government actually talks about maintaining the genetic purity of Israel (ah the irony) in the sense of making sure that at least 50% of Israelis are Jewish so that there can never be a 'democratic coup' inside Israel at election time
You're misleading people here, whether intentionally or not. Firstly, of course Israel wants to be a Jewish nation, that was the point of its creation. Remember the UN partition plan also called for no Jews to be allowed in Jordan, and in fact Jews are specifically barred from becoming citizens there. Same thing with other Arab countries, Jews are inferior or forbidden from becoming citizens. So if you criticize Israel, at least criticize the rest of the Arab Leage too.
And as far as being a Jewish nation, given treatment of Jews through history (Obviously Holocaust, but also pograms in Russia, Inquisition in Spain, being inferior dhimmis in Arab lands, etc) the point of Israel is to create an outl
I've come up with that argument myself a few years ago, I've never heard anyone else bring it up. Perhaps the silence of established climatologists speaks of the validity of the argument.
But anyway, as you say "same tired old objections to wind power", that implies people have brought up this concern long before me. And if so then the wind-power people and/or climatologists should have well-reasoned scientific explanations to easily refute it. Do you know of any such refutation?
Oh, I agree with you. I was bringing it up as a possible side effect of massive wind harvesting. I'm not running around claiming the sky is falling w/ wind power, it's just something I've pondered (actually while sailing past a number of windmills). And it's something that I haven't seen anybody bring up before.
I think the physics of my argument makes sense, the question is in terms of the scale of the energy involved. I'm certainly not insightful enough to get this order-of-magnitude estimate from what little I know about climatology. But it seems you agree, at least somewhat, on my hypotheses. Neither of us know the relavent scale of possible climate change (maybe femto-degrees celcius, maybe more), but that's fine.
At least I presented a somewhat defined argument, though. My area of research verges on nanotech, and every time nanotech is brought up on slashdot people run around with doomsday grey-goo scenarios. Yet not one of these people has presented a valid biochemical theory of how this would work. It's just rampant fear-mongering of something they don't understand, kind of like radioactivity in the 40's and 50's [pop culture example : spiderman was originally bit by a radioactive spider in the comics, in the movie he was bit by a genetically-modified spider].
Actually, Bush never pardoned Clinton, he said he had no intention of doing that. So interestingly enough, Bush may have set himself up for his successor to specifically not pardon him.
Anyway, it would be an interesting, perhaps useful, topic for the climatologists to study.
So back in your first post you said at the end "Wass even claims an undergrad degree in physics. He really should know better." Just for purposes of closure and/or beating a dead horse, do you still feel that way?
Hahaha, see the time I posted that comment. I dunno why I thought of cosmetologist instead of meteorologist. peace out.