Then maybe, as a highly visible public official, he should have kept his mouth shut until he'd consulted the public health people who actually know what they're talking about. I suspect he knows how to use a telephone.
Not having gone to MIT myself, I always wondered if the MIT phone system really had the following error recording?
I'm sorry, you've reached an imaginary number at the Massachusetts Institute of Technology. Please rotate your dial 90 degrees and try your call again.
Others have already mentioned the dot-matrix printer, but there was a big one before that: the high speed line printer. They were too expensive for individuals, but they certainly were a familiar sound to 1970s programming students like me.
There were two main types: the drum printer and the chain printer. The drum printer was cheaper and therefore much more common. The drum, which contained all the characters in a given font, rotated once for each row printed. An entire row was printed simultaneously; a separate solenoid-driven hammer in each column fired at the right instant to print the desired character in that column. You could easily tell from across the room whether your program had failed to compile or if execution ended with a core (!) dump. The burst pages between jobs had their own highly characteristic sound.
A related sound is that of ripping fanfold line printer paper to separate jobs. Who uses any kind of fanfold paper these days? Or even paper...?
Oh, and let's not forget the sound of the Hollerith (IBM punch card) reader...
Is NK still off the net? About a half hour ago I had no trouble reaching the sites
www.kcna.kp - 175.45.177.74 / 175.45.176.71
naenara.com.kp - 175.45.176.67 / 175.45.177.77
According to https://www.northkoreatech.org..., both sites are physically hosted inside North Korea. I see that both are in the 175.45.176.0/22 block that whois says is assigned to North Korea, and traceroute shows an extra latency (satellite hop?) for that network past China.
Is that their only net block? A/22 is 1024 addresses, which I keep hearing is the total number for the entire country.
It's a little hard to believe it's insulation degradation despite that.au recalls website entry. When insulation degrades, you tend to get short circuits that trip circuit breakers rather rapidly.
It seems more likely to be an undersized or underprotected conductor, e.g., a multistrand conductor in which flexing from improper strain relief can break most of the strands, increasing the local series resistance and heat dissipation and possibly leading to a complete conductor failure with series arcing. Only an arc-fault protector would trip on a failure like this, and those breakers are still uncommon in the US even though they're required in much new construction.
It would also seem that cord failures would be more likely in North America, Japan and other 100-120V countries because a universal switching supply producing a given amount of power will require twice the line current draw and produce 4x the heat dissipation (I^2 R) in a high resistance section of cord as it would in a country with a 230-240V supply voltage.
Because of inherent drift, inertial navigation is inherently suited only to fast vehicles that get to where they're going in just a few minutes or hours, e.g., planes and missiles. Cargo ships do not qualify. It is best combined with GPS to "flywheel" through outages (e.g., vehicles in tunnels) and so it can be automatically recalibrated whenever GPS is available.
Besides LORAN-C, there used to be another low frequency radio navigation system even better suited for global shipping: Omega. It operated on even lower frequencies, in the 10-14 kHz (yes, kHz) range, and had worldwide reach unlike LORAN-C which was only regional. It was shut down in 1997.
I certainly wouldn't bet that GPS satellites couldn't be destroyed, but most anti-sat weapons demonstrated so far work only on low altitude orbits. The US systems consist essentially of lobbing a small suborbital missile up in the path of the target satellite. Destroying a GPS satellite in a 20,000 km orbit takes a much bigger launch vehicle and considerably more time, and would be much harder to conceal from US space sensors.
LORAN-C would probably be rather resistant to EMP. Like just about everything military, the transmitting equipment would be designed to be EMP-resistant, and receiving equipment on vehicles would not be particularly susceptible. It's stuff with long cables that picks up EMP.
LORAN-C is certainly much more jam-resistant than GPS. The transmitter power levels are/were enormously higher, some in the megawatt range, to overcome natural background noise and antenna inefficiency. Even the large towers used are only a small fraction of a wavelength (3 km).
Also, LORAN-C operates by groundwave propagation (that's why the frequency is so low) so it's not very sensitive to solar activity.
That was probably LORAN-A, with which we used to share the 160m band (1.8-2.0 MHz). LORAN-C operates (or operated) in a dedicated allocation at 100 kHz. LORAN-A was shut down quite a few decades ago.
Actually, the US military has a very simple way of selectively shutting down GPS: they locally jam the L1 frequency. The satellites also transmit on a second frequency, L2, with an encrypted, high precision "P(Y)" code for which the keys are closely controlled. They have receivers that can work with just the P(Y)-code, so it doesn't matter to them if L1 is jammed.
Yeah, to have local governments build and maintain networks that serve all comers, commercial and private, while recovering all costs from usage-based user fees would be, dare I say it, socialism!
Next thing you know, the socialists will even propose to have local governments build and maintain roads for the public good!
The problem is ITAR - International Traffic in Arms Regulations. The idea was to keep cheap civilian receivers from being used in ICBMs. For that reason, there's an altitude and velocity limit, but the language was ambiguous. Some manufacturers interpreted it as an altitude AND a velocity, others interpreted it as an OR. The latter create the problem.
Your explanation is pretty much correct. But getting higher with a balloon is literally exponentially more difficult because that's exactly how the density of the atmosphere decreases with height. Your balloon has to expand exponentially as it climbs, and exponentials are not functions to be trifled with.
The vertical distance over which the atmospheric density decreases to 1/e of its starting value is the "scale height", and for the earth it is an average of 7.6 km (it varies with temperature). But you can see that just getting to 30 km (100,000') is already about 4 scale heights, with your balloon expanding by a factor of e^4. Even that much is harder than it looks because the balloon expands as rises, and the gas inside cools adiabatically, causing its density to increase. Even in thermal equilibrium with the air outside, that air is awfully cold, which doesn't help decrease the lifting gas density.
I think 100 km is completely out of the question. That's the Karman line, and it was chosen as roughly the altitude where an airplane could not generate enough lift to hold itself up even if it was going at orbital velocity. That's not a lot of air.
Not quite. Assuming "100k" means "100 km", conventionally chosen as the edge of space, getting there going straight up from 30 km (an easy weather balloon altitude) requires an upward force greater than the weight of the payload. Anything less and you'll just fall back to earth.
If you do this with a rocket (what else would you use?) you will find that doing it slowly is *very* expensive in propellant. In rocketry this is called "gravity loss", and it's one of the reasons rockets don't just go straight up to space even when the intent is to escape the earth. They fly an arched path known as a 'gravity turn': just enough altitude is gained to reduce air drag to an acceptable level while you try to build up horizontal velocity as fast as you can. The less time you spend with your rocket anything but horizontal, the lower your gravity losses will be and the more hard-earned rocket impulse you can devote to getting orbital velocity and *staying* in space.
Sorry, but the rules make no distinction between licensed and unlicensed spectrum. If you deliberately interfere with someone else's radio communications, you are breaking the rules.
Marriott's reply is laughable. It might work on unsophisticated readers but not anyone who knows anything about WiFi. They said they wanted to "protect" their guests against "rogue" access points. Well, if those "rogue" access points were spoofing Marriott's own SSID, they might have a point. But I certainly don't set my own portable hotspot SSID to that of any hotel. It's set to something quite unique, and it's encrypted. Nobody is going to mistake it for a hotel's network, much less actually associate with it.
The Christian fundies' fear of Sharia Law is one of the most ironically amusing things to come out of them in recent years. If they didn't spend so much time railing against our consitutitional separation of church and state, maybe, just maybe they might realize that it's exactly what protects them from such an (unlikely) threat.
And civil unrest becomes vastly more likely in a future with runaway global warming and the climatic changes, floods, draughts, food shortages, rising sea levels, mass extinctions, habitat destruction, economic upheavals and the like it will bring. Nuclear power, wind, solar, hydro and geothermal are ALL essential to combat it.
CO2's atmospheric lifetime is something like 1,000 years. How come those who fret about the longevity of nuclear waste never seem to talk about this? With fast reactors that burn the actinides (including plutonium) as fuel, the remaining fission products decay to the level of the original uranium ore (while being considerably more compact) in only a few hundred years, much less than the atmospheric lifetime of CO2.
The hype about "carbon capture" is just that -- hype. But it serves one useful purpose: its utter impracticality shows just how minor the nuclear waste "problem" is by comparison.
Not far from Yucca Mountain you will find hundreds if not thousands of craters under which are buried the fission and activation products of decades of US nuclear testing. They're not reprocessed and contained in silica glass, they were simply mixed (quite violently) with the soil and rock. And yet they don't seem to go anywhere.
There is no need for Yucca Mountain to contain reactor waste for even a hundred years because it will surely be removed and burned as fuel in fast reactors. Once people wake up to the fact that global warming is a vastly greater threat than nuclear power, and that nuclear power is just as essential as wind, solar, geothermal and hydro in combating it, people will realize that "spent" fuel from light water reactors is far too valuable to just throw away.
Even with cheap solar and wind we will still need nuclear, at least until somebody perfects a cheap, reliable and long-lived utility scale battery. Otherwise we'll never be able to retire all the CO2-belching fossil-fuel plants to match the varying supply with the varying demand.
I agree that waste in casks at nuclear power plants is reasonably safe but it would still be better to move it to Yucca Mountain. If nothing else, security would be a lot cheaper.
It's utterly ridiculous that all that money was spent on a waste repository that, thanks to NIMBYism on the part of Nevada politicians, doesn't look like it'll be used any time soon.
At least nuclear waste is the one form of toxic waste that will eventually go away on its own. Arsenic, mercury, lead, thallium and other chemical poisons remain toxic forever.
Yeah, and we should also ban municipalities from building roads because they discourage private investment in toll roads. All the roads, including the street in front of your house, ought to be sold to UPS. You'd have to get their permission to drive your car on their roads. Since they'd be private property, they'd be within their rights to make any arbitrary rules they wanted. They could ban certain makes or kinds or colors of cars. They could allow you to drive only to certain pre-approved destinations.
And don't even think about trying to create a package delivery service to compete with them.
Are you sure about this? Would it in fact be possible to gain access to all past stored emails by logging a future user session? Or was it only possible to gain access to future emails by recording a copy of the incoming plaintext before encrypting them with the user's public key?
This is an honest question; I hadn't even heard of Lavabit until today (I would have been a customer if I had) so I only know what I've read.
Even before today, the past several months have proved what we've all long suspected: a security model that requires the users to trust a commercial service provider is simply not workable. Even (especially) in the United States.
Ideally, a security model shouldn't require you to trust anyone in the middle at all. If that's not possible (and for many services, it's not) it should rely on a large volunteer group, at least some of whom are honest. Something like TOR, though it has its own problems.
I think you have it basically right. As I understand Lavabit, they encrypted incoming email with a public key for which only the user had the private key. They could not provide plaintext of existing email to a government demand. So the government probably ordered them to keep plaintext copies of all future email, which would be technically possible. The only way to avoid it was to shut down the service altogether.
There'd be no reason to shut down the service if the demand was only for existing data as that would not relieve them of the requirement to fork it over.
At the moment their MX server is not accepting incoming SMTP connections, which lends weight to my theory. The government could still seize the domain name and set up their own inbound SMTP server, but hopefully the publicity has warned everyone away.
Right now there are two MX records for lavabit.com: mx.lavabit.com and lavabit.com, both of which resolve to IPv4 address 72.249.41.52. imap.lavabit.com also resolves to the same IPv4 address. Let's see if those records change...
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Then maybe, as a highly visible public official, he should have kept his mouth shut until he'd consulted the public health people who actually know what they're talking about. I suspect he knows how to use a telephone.
God forbid that some poor kid ever accidentally knock a softball over the White House fence. He'd never escape Gitmo.
I'm sorry, you've reached an imaginary number at the Massachusetts Institute of Technology. Please rotate your dial 90 degrees and try your call again.
There were two main types: the drum printer and the chain printer. The drum printer was cheaper and therefore much more common. The drum, which contained all the characters in a given font, rotated once for each row printed. An entire row was printed simultaneously; a separate solenoid-driven hammer in each column fired at the right instant to print the desired character in that column. You could easily tell from across the room whether your program had failed to compile or if execution ended with a core (!) dump. The burst pages between jobs had their own highly characteristic sound.
A related sound is that of ripping fanfold line printer paper to separate jobs. Who uses any kind of fanfold paper these days? Or even paper...?
Oh, and let's not forget the sound of the Hollerith (IBM punch card) reader...
Is NK still off the net? About a half hour ago I had no trouble reaching the sites www.kcna.kp - 175.45.177.74 / 175.45.176.71 naenara.com.kp - 175.45.176.67 / 175.45.177.77 According to https://www.northkoreatech.org..., both sites are physically hosted inside North Korea. I see that both are in the 175.45.176.0/22 block that whois says is assigned to North Korea, and traceroute shows an extra latency (satellite hop?) for that network past China. Is that their only net block? A /22 is 1024 addresses, which I keep hearing is the total number for the entire country.
"National Security" is the root password to the Constitution - me
It's a little hard to believe it's insulation degradation despite that .au recalls website entry. When insulation degrades, you tend to get short circuits that trip circuit breakers rather rapidly.
It seems more likely to be an undersized or underprotected conductor, e.g., a multistrand conductor in which flexing from improper strain relief can break most of the strands, increasing the local series resistance and heat dissipation and possibly leading to a complete conductor failure with series arcing. Only an arc-fault protector would trip on a failure like this, and those breakers are still uncommon in the US even though they're required in much new construction.
It would also seem that cord failures would be more likely in North America, Japan and other 100-120V countries because a universal switching supply producing a given amount of power will require twice the line current draw and produce 4x the heat dissipation (I^2 R) in a high resistance section of cord as it would in a country with a 230-240V supply voltage.
Because of inherent drift, inertial navigation is inherently suited only to fast vehicles that get to where they're going in just a few minutes or hours, e.g., planes and missiles. Cargo ships do not qualify. It is best combined with GPS to "flywheel" through outages (e.g., vehicles in tunnels) and so it can be automatically recalibrated whenever GPS is available.
Besides LORAN-C, there used to be another low frequency radio navigation system even better suited for global shipping: Omega. It operated on even lower frequencies, in the 10-14 kHz (yes, kHz) range, and had worldwide reach unlike LORAN-C which was only regional. It was shut down in 1997.
I certainly wouldn't bet that GPS satellites couldn't be destroyed, but most anti-sat weapons demonstrated so far work only on low altitude orbits. The US systems consist essentially of lobbing a small suborbital missile up in the path of the target satellite. Destroying a GPS satellite in a 20,000 km orbit takes a much bigger launch vehicle and considerably more time, and would be much harder to conceal from US space sensors.
Jamming and spoofing are the much bigger threats.
LORAN-C would probably be rather resistant to EMP. Like just about everything military, the transmitting equipment would be designed to be EMP-resistant, and receiving equipment on vehicles would not be particularly susceptible. It's stuff with long cables that picks up EMP. LORAN-C is certainly much more jam-resistant than GPS. The transmitter power levels are/were enormously higher, some in the megawatt range, to overcome natural background noise and antenna inefficiency. Even the large towers used are only a small fraction of a wavelength (3 km). Also, LORAN-C operates by groundwave propagation (that's why the frequency is so low) so it's not very sensitive to solar activity.
That was probably LORAN-A, with which we used to share the 160m band (1.8-2.0 MHz). LORAN-C operates (or operated) in a dedicated allocation at 100 kHz. LORAN-A was shut down quite a few decades ago.
Actually, the US military has a very simple way of selectively shutting down GPS: they locally jam the L1 frequency. The satellites also transmit on a second frequency, L2, with an encrypted, high precision "P(Y)" code for which the keys are closely controlled. They have receivers that can work with just the P(Y)-code, so it doesn't matter to them if L1 is jammed.
Yeah, to have local governments build and maintain networks that serve all comers, commercial and private, while recovering all costs from usage-based user fees would be, dare I say it, socialism! Next thing you know, the socialists will even propose to have local governments build and maintain roads for the public good!
The problem is ITAR - International Traffic in Arms Regulations. The idea was to keep cheap civilian receivers from being used in ICBMs. For that reason, there's an altitude and velocity limit, but the language was ambiguous. Some manufacturers interpreted it as an altitude AND a velocity, others interpreted it as an OR. The latter create the problem.
Your explanation is pretty much correct. But getting higher with a balloon is literally exponentially more difficult because that's exactly how the density of the atmosphere decreases with height. Your balloon has to expand exponentially as it climbs, and exponentials are not functions to be trifled with. The vertical distance over which the atmospheric density decreases to 1/e of its starting value is the "scale height", and for the earth it is an average of 7.6 km (it varies with temperature). But you can see that just getting to 30 km (100,000') is already about 4 scale heights, with your balloon expanding by a factor of e^4. Even that much is harder than it looks because the balloon expands as rises, and the gas inside cools adiabatically, causing its density to increase. Even in thermal equilibrium with the air outside, that air is awfully cold, which doesn't help decrease the lifting gas density. I think 100 km is completely out of the question. That's the Karman line, and it was chosen as roughly the altitude where an airplane could not generate enough lift to hold itself up even if it was going at orbital velocity. That's not a lot of air.
Not quite. Assuming "100k" means "100 km", conventionally chosen as the edge of space, getting there going straight up from 30 km (an easy weather balloon altitude) requires an upward force greater than the weight of the payload. Anything less and you'll just fall back to earth. If you do this with a rocket (what else would you use?) you will find that doing it slowly is *very* expensive in propellant. In rocketry this is called "gravity loss", and it's one of the reasons rockets don't just go straight up to space even when the intent is to escape the earth. They fly an arched path known as a 'gravity turn': just enough altitude is gained to reduce air drag to an acceptable level while you try to build up horizontal velocity as fast as you can. The less time you spend with your rocket anything but horizontal, the lower your gravity losses will be and the more hard-earned rocket impulse you can devote to getting orbital velocity and *staying* in space.
Sorry, but the rules make no distinction between licensed and unlicensed spectrum. If you deliberately interfere with someone else's radio communications, you are breaking the rules.
Marriott's reply is laughable. It might work on unsophisticated readers but not anyone who knows anything about WiFi. They said they wanted to "protect" their guests against "rogue" access points. Well, if those "rogue" access points were spoofing Marriott's own SSID, they might have a point. But I certainly don't set my own portable hotspot SSID to that of any hotel. It's set to something quite unique, and it's encrypted. Nobody is going to mistake it for a hotel's network, much less actually associate with it.
The Christian fundies' fear of Sharia Law is one of the most ironically amusing things to come out of them in recent years. If they didn't spend so much time railing against our consitutitional separation of church and state, maybe, just maybe they might realize that it's exactly what protects them from such an (unlikely) threat.
CO2's atmospheric lifetime is something like 1,000 years. How come those who fret about the longevity of nuclear waste never seem to talk about this? With fast reactors that burn the actinides (including plutonium) as fuel, the remaining fission products decay to the level of the original uranium ore (while being considerably more compact) in only a few hundred years, much less than the atmospheric lifetime of CO2.
The hype about "carbon capture" is just that -- hype. But it serves one useful purpose: its utter impracticality shows just how minor the nuclear waste "problem" is by comparison.
Not far from Yucca Mountain you will find hundreds if not thousands of craters under which are buried the fission and activation products of decades of US nuclear testing. They're not reprocessed and contained in silica glass, they were simply mixed (quite violently) with the soil and rock. And yet they don't seem to go anywhere. There is no need for Yucca Mountain to contain reactor waste for even a hundred years because it will surely be removed and burned as fuel in fast reactors. Once people wake up to the fact that global warming is a vastly greater threat than nuclear power, and that nuclear power is just as essential as wind, solar, geothermal and hydro in combating it, people will realize that "spent" fuel from light water reactors is far too valuable to just throw away.
Even with cheap solar and wind we will still need nuclear, at least until somebody perfects a cheap, reliable and long-lived utility scale battery. Otherwise we'll never be able to retire all the CO2-belching fossil-fuel plants to match the varying supply with the varying demand.
I agree that waste in casks at nuclear power plants is reasonably safe but it would still be better to move it to Yucca Mountain. If nothing else, security would be a lot cheaper. It's utterly ridiculous that all that money was spent on a waste repository that, thanks to NIMBYism on the part of Nevada politicians, doesn't look like it'll be used any time soon. At least nuclear waste is the one form of toxic waste that will eventually go away on its own. Arsenic, mercury, lead, thallium and other chemical poisons remain toxic forever.
Yeah, and we should also ban municipalities from building roads because they discourage private investment in toll roads. All the roads, including the street in front of your house, ought to be sold to UPS. You'd have to get their permission to drive your car on their roads. Since they'd be private property, they'd be within their rights to make any arbitrary rules they wanted. They could ban certain makes or kinds or colors of cars. They could allow you to drive only to certain pre-approved destinations. And don't even think about trying to create a package delivery service to compete with them.
Are you sure about this? Would it in fact be possible to gain access to all past stored emails by logging a future user session? Or was it only possible to gain access to future emails by recording a copy of the incoming plaintext before encrypting them with the user's public key? This is an honest question; I hadn't even heard of Lavabit until today (I would have been a customer if I had) so I only know what I've read. Even before today, the past several months have proved what we've all long suspected: a security model that requires the users to trust a commercial service provider is simply not workable. Even (especially) in the United States. Ideally, a security model shouldn't require you to trust anyone in the middle at all. If that's not possible (and for many services, it's not) it should rely on a large volunteer group, at least some of whom are honest. Something like TOR, though it has its own problems.
I think you have it basically right. As I understand Lavabit, they encrypted incoming email with a public key for which only the user had the private key. They could not provide plaintext of existing email to a government demand. So the government probably ordered them to keep plaintext copies of all future email, which would be technically possible. The only way to avoid it was to shut down the service altogether. There'd be no reason to shut down the service if the demand was only for existing data as that would not relieve them of the requirement to fork it over. At the moment their MX server is not accepting incoming SMTP connections, which lends weight to my theory. The government could still seize the domain name and set up their own inbound SMTP server, but hopefully the publicity has warned everyone away. Right now there are two MX records for lavabit.com: mx.lavabit.com and lavabit.com, both of which resolve to IPv4 address 72.249.41.52. imap.lavabit.com also resolves to the same IPv4 address. Let's see if those records change...