I suggest heavens-above.com as another good possibility, because they allow for very careful localization (you can feed in your town location or your lat/long) and they'll provide a map showing the comet's position against the background stars over time for your location.
They also provide such maps for the ISS, the HST, and most amazing of all, iridium flares. One of my fondest-ever memories was working night-shift at a big manufacturing place and getting all the geeks in the place out in the parking lot at 11 PM, all staring up in the sky, saying, "WHAT are we going to see?" and suddenly *FWOOOM* there's the brightest flash anyone's ever seen and then it's gone and everyone's like "what the HELL?"
You're closer to convincing me than anyone else. So tell me why the wavelength of light matters: it's longitudinal, not transverse, so what limits it? Does light have a diameter at all? I guess there's an amplitude, some function of the electronic/magnetic components. I know they're 90 degrees to one another. Are the two the same amplitude? Does it matter that it runs into things? I guess an electric field shouldn't be able to cross a conductor, but is that absolute, or is there some penetration into the conductive surface?
Here's an unbelievably cool demo of why return paths matter so very, very much. Unfortunately it takes some expensive equipment. Take about 50-100' of coax. Strip the ends, and put a 50 ohm resistor between the center and the braid on one end. Attach the braid on one end to the braid on the other end with a 2" wire. Put DC on it and put a current probe around the 2" wire. 99.9% of the electricity flowing, is flowing through the 2" wire. Now put a 1 MHz square wave down the center conductor and measure the 2" wire. Roughly 15% of the electricity flowing, is flowing through the 2" wire. The rest is going back through the coax shielding, because it's the path of lowest impedance.
That's why coax is good stuff.
There are good ways of coping with noise coupling, but if what you're doing is reducing a signal path's reception of noise, it almost always involves making sure you have your current return path close to and, if possible, surrounding your signal path, which is why coax is useful. There are times when it's good to use the outer braid as a guard, especially if you have grounding issues, but then you really want to be using three-conductor coax, where you send the signal down the center, return it down the inner braid, and use the outer braid as the guard.
kay, I've thought about it some more. So the wavelength's 375 nm: so what? Light's a longitudinal wave, not transverse. I'm not sure light *has* a diameter.
The issue with shoving RF down coax is one of minimizing impedance, not wavelength, which is why the same coax works well across a decade or so of RF. Antenna length *does* need to scale with wavelength, but unless you want your waveguide to act like an antenna, you probably don't want it to be tuned, or to need to be tuned, to the wavelength in question.
Except that 99% of the time, coax means signal down the center, and signal return path (or guard, or whatever you want to call a conduction path) back through the cladding, which is the point of the shielding. That's why we use coax for RF, because it minimizes the loop area and coaligns the signal with the return, rather than just a signal path and a current return path running out to the antenna separately, each with a 20mm outdoor-exposure-rated rubber casing.
Read Henry Petrowski's book, "To Engineer Is Human" some time. The point of the book is: an engineer, whether bridge or software, is building a compromise between deadlines, money, user requirements, and laws of nature. As time marches on, that compromise will *always* tilt towards deadlines and money, and eventually it will break, at which point we've learned something for next time.
Will someone tell me *why* they did this? Yes, it's very cool. But the whole and only point of coax, as they talk about in TFA, is that it minimizes electrical influence. If you're using light, there *isn't* any electrical interference, either as a transmitter or a receiver. That's one of the major benefits of using light. So it's kind of pointless to make a coax, unless you really want a two-channel transmitter where one's a funny ring-shape. In which case, why not make optical ribbon cable? Which brings up a wholly separate question: one reason industry has moved from parallel to very-high-speed serial is that you don't have to worry about timing and synchronicity, which are primarily due to impurities in copper. Is this an issue with optical? Coz the engineering is generally easier to run ten existing lines in parallel than to make one line ten times faster, if you don't have to worry about synchronizing them.
Turbines aren't more efficient. Read about best specific fuel consumption. Even at full power, where turbines do best, even the best turbines are only at about what reasonable gasoline engines do all the time, while purpose-built reciprocating engines can do nearly twice as well.
Add to that, that at 20% of full rated power a recip is using about 30% of the fuel it would at full rated power, whereas a turbine is using about 75% of the fuel it would at full rated power, and you come up with some good reasons to use reciprocating engines.
There are combined-cycle turbine engines that do *very* well, but those are different beasts from what we're discussing here, I think.
>even most turbines on jet aircraft are built to contain their massive, extremely high-speed turbines,
I'm not sure I believe this. Here's a 2004 NTSB report on a helicopter crash where the entire turbine wheel shot out of the helicopter after breaking. Here are reports of four uncontained turbine failures on Delta aircraft in the last 10 years, using recent aircraft. John Deakin who has 36,000 hours flying 747's, says that often a turbine can operate for hundreds of hours after throwing a blade, so it's not like it's always a catastrophe, but a cursory survey of google and the NTSB literature indicates that there's no way failures of the turbine section are always, or even usually, contained.
By the way, everything other than fighter jets already mixes the turbine exhaust with ambient air: they're called high-bypass engines, and they're essentially ducted turboprop engines.
I worked at a place that actually built servers and desktops for Dell and HP, among others. You're correct: we built to a required price point. HP servers were 100% functionality tested, multiple times, in hot/cold chambers. HP desktops were 100% functionality tested. Dell desktops were power-on tested. We built motherboards for someone, I don't know whom, that weren't even power-on tested, just shorts-tested on automated test equipment.
In arid states like Colorado, there are rest stops on the Interstate that have silicone water traps in the urinals to prevent them evaporating, but it's harder to get silicone oils in small quantities.
I think it's worth your time to at least skim "Amusing Ourselves To Death" and "How To Watch The TV News" some time. The former is probably his best (and best-known) book and is somewhat dated: at the time, his thesis was that there were two realistic futures for American society, the one predicted by Orwell's 1984 where a totalitarian government spied on people to keep them in check, and the one predicted by Aldous Huxley's Brave New World, in which people, as a group, abandoned their oversight of government because they were busy being distracted by drugs and entertainment. Postman claimed, as of 1987, that we'd taken the Huxley path, and at the time I think he was right; now, we're back to being able to head down either route (neither good.)
On the one hand, The brilliant media and cultural critic Neal Postman wrote -- and I'm summarizing several books here -- that we should pass a law that any time someone who isn't an expert in the field under discussion says anything about a subject, a big black banner should appear across the bottom of the screen, saying "THIS PERSON DOESN'T KNOW WHAT S/HE IS TALKING ABOUT."
On the *other* hand, Britney sure knows semiconductor physics. I point people at her explanation of VCSELs and how they work because it's way better than what I can crank out in a hurry.
Pain is a survival issue for animals, which is why they have pain receptors. If a robot doesn't have pain receptors, why would it care if it gets kicked? If a robot can seamlessly replace components that are broken, what would the use of pain receptors be? Without pain there isn't any physical suffering, so there isn't any reason for concern.
Suffering from the perception of inequality is a wholly different, and perfectly valid, concern, although Douglas Adams (among others) has already addressed that with food genetically engineered to actively look forward to being eaten. I think that's an ethical morass, but if you make robots that are programmed to enjoy what they do, and enjoy being in a secondary position in society, they won't suffer. This implies that the only AI's that will suffer are those that become autonomously self-aware, and are capable of recognizing and assessing their situation.
Ditto that. I only torrent stuff that is completely unavailable commercially: so-called "out-of-print" material. (What the hell: it's a bunch of zeros and ones, just like all the other zeros and ones. How can it be out of print?) If you're trying to get soundtracks from obscure 1980's movies or ripped '50's jazz LP's, it's pretty frequent that the number of seeders vastly outnumbers the number of people who are still trying to find it.
Add to that the ability to eat spicy food. My 112 pound girlfriend routinely describes me as a wimp because I won't eat thai chili peppers straight. I'm a bike racer and weightlifter and have taken 10 years of various martial arts, but I'm the wimp.
>employer-provided health insurance (cheapest price), health insurance you paid for yourself (ripoff prices), or no health insurance (extortion).
People keep saying this and I'm curious because it's not my experience. I've paid cash for both my medical care and my girlfriend's, for emergency room injuries to routine ob/gyn, and in many cases, particularly at the ob/gyn, when they found out I wasn't insured they'd lower their voices, look around, and say "well, actually, we're only going to charge you about 60% of what's written there on the bill, because we don't have to do any paperwork to get the money." Now, it's very possible that the times that nobody's said anything, they were wildly overcharging me compared to an insured person, and since they absolutely refuse to release competitive rate information I have no way of knowing. But the impression I've gotten is that I've been getting good deals because I'm willing to pay, in full, immediately.
The human form is called Creutzfeldt-Jakob disease, and it occurs *spontaneously* in about 1 in a million people. It has been observed throughout the world, although until recently the disease wasn't recognized as such. The problem in New Guinea, where it's called kuru (and might/might not be exactly the same as CJD) was that it was much, much higher than that because people were eating other people, which is an effective transmission tactic, where casual contact probably isn't. (As opposed to a similar disease that strikes elk and deer in the Rocky Mountains, where saliva sharing appears to be sufficient to cause infection.) Wikipedia, of course, has more details.
I haven't ever loitered over heavy traffic when I'm flying, coz some idiot will decide I'm about to bomb a whatever's valuable nearby with my Cessna that weighs less than an old VW Bug, so I'm curious: are the waves truly stationary, or do they move? forwards or backwards? Obviously, the tail end is going to move backwards, upstream so to speak, but I've often seen situations on the ground where there was a big slowdown, then a speedup, then a policeman at an accident scene, so it seemed like the beginning of the slowdown was moving upstream. I can imagine a wave moving downstream under some circumstances, but haven't ever seen it happen.
If I recall correctly, many brand-new cars take a a whole lot more than 170 feet. This indicates an older Landcruiser takes 300 feet at that speed if the pavement's wet, and a brand-new one still takes 180 feet. I think I recall a recent Car&Driver showing several very high-end luxury cars with 200-foot stopping distances, on dry pavement, at 70 mph, with professional drivers.
So TFA mentions enormous black holes. What happens to them? What's the lifecycle? At some point do they get big enough to suck themselves into their own little inaccessable chunk of spacetime? (if so, aren't they removing vast amounts of matter from the universe? How would that affect expansion?) Or does Hawking radiation manage to eventually make a black hole evaporate away? While I'm at it, is there any evidence that black holes attract dark matter?
Slashdot Mirror
I suggest heavens-above.com as another good possibility, because they allow for very careful localization (you can feed in your town location or your lat/long) and they'll provide a map showing the comet's position against the background stars over time for your location.
They also provide such maps for the ISS, the HST, and most amazing of all, iridium flares. One of my fondest-ever memories was working night-shift at a big manufacturing place and getting all the geeks in the place out in the parking lot at 11 PM, all staring up in the sky, saying, "WHAT are we going to see?" and suddenly *FWOOOM* there's the brightest flash anyone's ever seen and then it's gone and everyone's like "what the HELL?"
I'm going to have to think about that, but that's a great answer.
You're closer to convincing me than anyone else.
So tell me why the wavelength of light matters: it's longitudinal, not transverse, so what limits it? Does light have a diameter at all? I guess there's an amplitude, some function of the electronic/magnetic components. I know they're 90 degrees to one another. Are the two the same amplitude? Does it matter that it runs into things? I guess an electric field shouldn't be able to cross a conductor, but is that absolute, or is there some penetration into the conductive surface?
Here's an unbelievably cool demo of why return paths matter so very, very much. Unfortunately it takes some expensive equipment.
Take about 50-100' of coax. Strip the ends, and put a 50 ohm resistor between the center and the braid on one end. Attach the braid on one end to the braid on the other end with a 2" wire. Put DC on it and put a current probe around the 2" wire. 99.9% of the electricity flowing, is flowing through the 2" wire. Now put a 1 MHz square wave down the center conductor and measure the 2" wire. Roughly 15% of the electricity flowing, is flowing through the 2" wire. The rest is going back through the coax shielding, because it's the path of lowest impedance.
That's why coax is good stuff.
There are good ways of coping with noise coupling, but if what you're doing is reducing a signal path's reception of noise, it almost always involves making sure you have your current return path close to and, if possible, surrounding your signal path, which is why coax is useful. There are times when it's good to use the outer braid as a guard, especially if you have grounding issues, but then you really want to be using three-conductor coax, where you send the signal down the center, return it down the inner braid, and use the outer braid as the guard.
kay, I've thought about it some more. So the wavelength's 375 nm: so what? Light's a longitudinal wave, not transverse. I'm not sure light *has* a diameter.
The issue with shoving RF down coax is one of minimizing impedance, not wavelength, which is why the same coax works well across a decade or so of RF. Antenna length *does* need to scale with wavelength, but unless you want your waveguide to act like an antenna, you probably don't want it to be tuned, or to need to be tuned, to the wavelength in question.
Except that 99% of the time, coax means signal down the center, and signal return path (or guard, or whatever you want to call a conduction path) back through the cladding, which is the point of the shielding. That's why we use coax for RF, because it minimizes the loop area and coaligns the signal with the return, rather than just a signal path and a current return path running out to the antenna separately, each with a 20mm outdoor-exposure-rated rubber casing.
I must've missed that part, and I did read it. hm, weird.
>we've been building bridges for thousands of years
And despite that, they still fall down.
Read Henry Petrowski's book, "To Engineer Is Human" some time. The point of the book is: an engineer, whether bridge or software, is building a compromise between deadlines, money, user requirements, and laws of nature. As time marches on, that compromise will *always* tilt towards deadlines and money, and eventually it will break, at which point we've learned something for next time.
Will someone tell me *why* they did this? Yes, it's very cool. But the whole and only point of coax, as they talk about in TFA, is that it minimizes electrical influence.
If you're using light, there *isn't* any electrical interference, either as a transmitter or a receiver. That's one of the major benefits of using light.
So it's kind of pointless to make a coax, unless you really want a two-channel transmitter where one's a funny ring-shape. In which case, why not make optical ribbon cable?
Which brings up a wholly separate question: one reason industry has moved from parallel to very-high-speed serial is that you don't have to worry about timing and synchronicity, which are primarily due to impurities in copper. Is this an issue with optical? Coz the engineering is generally easier to run ten existing lines in parallel than to make one line ten times faster, if you don't have to worry about synchronizing them.
I guess you missed the part where Islam preaches that Jesus lives in, and rules, Heaven (or at least one of the seven heavens.) Kind of like claiming Alabama and California have the same leader, isn't it?
Turbines aren't more efficient.
Read about best specific fuel consumption. Even at full power, where turbines do best, even the best turbines are only at about what reasonable gasoline engines do all the time, while purpose-built reciprocating engines can do nearly twice as well.
Add to that, that at 20% of full rated power a recip is using about 30% of the fuel it would at full rated power, whereas a turbine is using about 75% of the fuel it would at full rated power, and you come up with some good reasons to use reciprocating engines.
There are combined-cycle turbine engines that do *very* well, but those are different beasts from what we're discussing here, I think.
>even most turbines on jet aircraft are built to contain their massive, extremely high-speed turbines,
I'm not sure I believe this.
Here's a 2004 NTSB report on a helicopter crash where the entire turbine wheel shot out of the helicopter after breaking.
Here are reports of four uncontained turbine failures on Delta aircraft in the last 10 years, using recent aircraft.
John Deakin who has 36,000 hours flying 747's, says that often a turbine can operate for hundreds of hours after throwing a blade, so it's not like it's always a catastrophe, but a cursory survey of google and the NTSB literature indicates that there's no way failures of the turbine section are always, or even usually, contained.
By the way, everything other than fighter jets already mixes the turbine exhaust with ambient air: they're called high-bypass engines, and they're essentially ducted turboprop engines.
I worked at a place that actually built servers and desktops for Dell and HP, among others. You're correct: we built to a required price point. HP servers were 100% functionality tested, multiple times, in hot/cold chambers. HP desktops were 100% functionality tested. Dell desktops were power-on tested. We built motherboards for someone, I don't know whom, that weren't even power-on tested, just shorts-tested on automated test equipment.
Engine oil doesn't go rancid.
In arid states like Colorado, there are rest stops on the Interstate that have silicone water traps in the urinals to prevent them evaporating, but it's harder to get silicone oils in small quantities.
I think it's worth your time to at least skim "Amusing Ourselves To Death" and "How To Watch The TV News" some time. The former is probably his best (and best-known) book and is somewhat dated: at the time, his thesis was that there were two realistic futures for American society, the one predicted by Orwell's 1984 where a totalitarian government spied on people to keep them in check, and the one predicted by Aldous Huxley's Brave New World, in which people, as a group, abandoned their oversight of government because they were busy being distracted by drugs and entertainment. Postman claimed, as of 1987, that we'd taken the Huxley path, and at the time I think he was right; now, we're back to being able to head down either route (neither good.)
On the one hand, The brilliant media and cultural critic Neal Postman wrote -- and I'm summarizing several books here -- that we should pass a law that any time someone who isn't an expert in the field under discussion says anything about a subject, a big black banner should appear across the bottom of the screen, saying "THIS PERSON DOESN'T KNOW WHAT S/HE IS TALKING ABOUT."
On the *other* hand, Britney sure knows semiconductor physics. I point people at her explanation of VCSELs and how they work because it's way better than what I can crank out in a hurry.
Pain is a survival issue for animals, which is why they have pain receptors. If a robot doesn't have pain receptors, why would it care if it gets kicked? If a robot can seamlessly replace components that are broken, what would the use of pain receptors be? Without pain there isn't any physical suffering, so there isn't any reason for concern.
Suffering from the perception of inequality is a wholly different, and perfectly valid, concern, although Douglas Adams (among others) has already addressed that with food genetically engineered to actively look forward to being eaten. I think that's an ethical morass, but if you make robots that are programmed to enjoy what they do, and enjoy being in a secondary position in society, they won't suffer. This implies that the only AI's that will suffer are those that become autonomously self-aware, and are capable of recognizing and assessing their situation.
Ditto that. I only torrent stuff that is completely unavailable commercially: so-called "out-of-print" material. (What the hell: it's a bunch of zeros and ones, just like all the other zeros and ones. How can it be out of print?) If you're trying to get soundtracks from obscure 1980's movies or ripped '50's jazz LP's, it's pretty frequent that the number of seeders vastly outnumbers the number of people who are still trying to find it.
Add to that the ability to eat spicy food. My 112 pound girlfriend routinely describes me as a wimp because I won't eat thai chili peppers straight. I'm a bike racer and weightlifter and have taken 10 years of various martial arts, but I'm the wimp.
It's all about choosing your battles...
>employer-provided health insurance (cheapest price), health insurance you paid for yourself (ripoff prices), or no health insurance (extortion).
People keep saying this and I'm curious because it's not my experience. I've paid cash for both my medical care and my girlfriend's, for emergency room injuries to routine ob/gyn, and in many cases, particularly at the ob/gyn, when they found out I wasn't insured they'd lower their voices, look around, and say "well, actually, we're only going to charge you about 60% of what's written there on the bill, because we don't have to do any paperwork to get the money."
Now, it's very possible that the times that nobody's said anything, they were wildly overcharging me compared to an insured person, and since they absolutely refuse to release competitive rate information I have no way of knowing. But the impression I've gotten is that I've been getting good deals because I'm willing to pay, in full, immediately.
The human form is called Creutzfeldt-Jakob disease, and it occurs *spontaneously* in about 1 in a million people. It has been observed throughout the world, although until recently the disease wasn't recognized as such.
The problem in New Guinea, where it's called kuru (and might/might not be exactly the same as CJD) was that it was much, much higher than that because people were eating other people, which is an effective transmission tactic, where casual contact probably isn't. (As opposed to a similar disease that strikes elk and deer in the Rocky Mountains, where saliva sharing appears to be sufficient to cause infection.)
Wikipedia, of course, has more details.
I haven't ever loitered over heavy traffic when I'm flying, coz some idiot will decide I'm about to bomb a whatever's valuable nearby with my Cessna that weighs less than an old VW Bug, so I'm curious: are the waves truly stationary, or do they move? forwards or backwards? Obviously, the tail end is going to move backwards, upstream so to speak, but I've often seen situations on the ground where there was a big slowdown, then a speedup, then a policeman at an accident scene, so it seemed like the beginning of the slowdown was moving upstream. I can imagine a wave moving downstream under some circumstances, but haven't ever seen it happen.
If I recall correctly, many brand-new cars take a a whole lot more than 170 feet. This indicates an older Landcruiser takes 300 feet at that speed if the pavement's wet, and a brand-new one still takes 180 feet. I think I recall a recent Car&Driver showing several very high-end luxury cars with 200-foot stopping distances, on dry pavement, at 70 mph, with professional drivers.
Besides that, the person who owns the movie rights is apparently strongly opposed to making the sequel, on aesthetic and vengeful grounds.
They could probably get Peter, but Jeff has gotten very expensive. Yes, both characters were in the sequel.
So TFA mentions enormous black holes.
What happens to them? What's the lifecycle? At some point do they get big enough to suck themselves into their own little inaccessable chunk of spacetime? (if so, aren't they removing vast amounts of matter from the universe? How would that affect expansion?) Or does Hawking radiation manage to eventually make a black hole evaporate away?
While I'm at it, is there any evidence that black holes attract dark matter?