Browse the jobs yourself if you don't believe me. 98% of them say "US Citizen or Green Card holders only"
That is very interesting. I thought that that was illegal, except for defense jobs. Job discrimination on the basis of immigration status is not allowed. Or maybe that has changed...
All very true. One additional thing: the H1B worker has to have a Bachelor's Degree or equivalent. "Equivalent" could be 10 yrs work experience or something like that, but things are a lot easier if you do have the college degree.
I hope they're not using normal glass, which is technically a liquid. Look at windows in colonial houses; their bottom is thicker than their top.
True, but: - modern day glass may have better properties than colonial glass - this thing is going to be put on a satellite orbiting the earth. The zero gravity should help that problem.
Come to think of it: it may be a bigger challenge to keep the satellite's orbit stable for 50,000 years.
Nothing lasts forever, not even glass discs. Entropy and all that, also causes your razor blades to become dull by themselves. I guess they think the glass disc would still be readable after 50K years.
Spoiler Warning Don't read on if you think you want to read the story. The following spoils it a bit. However, it is essential to illustrate my point. . . . . . . . The story is about retrieving information from pottery. The idea is to restore the sounds that were around when people were making pottery centuries ago. I read somewhere that this was based on actual serious research. Anyhow, the scientists succeed, but are disappointed by what they can retrieve: middle-agers shouting warnings into the pot not to walk on this and this guy's land, because the sheep will get sick, and other nonsense like that. At the same time some other scientists are preparing a time capsule for the benefit of future generations. The conclusion of the story is: "what makes us think we are doing a better job than the people from the middle ages?"
I guess the same applies here: even if we would filter out all the crap ("l33t hax0rz in sp33z!"), are people really going to give a damn in 50K years?
Scientists already think that we pretty much know most of what there is to know...
Ah yes, I think Stephen Hawking is one of them. Well, I remember reading this statement made by Lord Kelvin around 1900 or so, where he said the same thing: "Physics is more or less complete. There are only two small problems left to be solved". Or something like that, forgive me for not quoting literally. Anyhow, one of the small problems led to the theory of relativity, the other to quantum mechanics.
Ok, you got me. I made a mistake. This was 8 years ago, we looked at something which sounded similar to 'NTP'. I can't remember what it was called exactly any more, and I'm not gonna waste more time on it. All I know is that we analyzed the problem, evaluated what was available, and made a decision.
Whatever. All I can remember that in those days we looked at NTP (or maybe it was NNTP??), and did not like the idea of going through and possibly maintaining 40,000 lines of C (that's the way it was in '94, or at least that's how I remember it). Our "homegrown NTP" as you call it wasn't even close to that. All we needed was a simple way to keep system clocks in line, with an accuracy of a few tenths of a second. We accomplished this in a few dozen lines of C++ (a generic message broadcasting mechanism over UDP was already implemented).
In hindsight you can always question decisions like that, but bottom line is that we had a simple problem, and we fixed it with a simple solution.
And the software (control system for rocket launches) has been in operational use since 1996, without any major problems, thank you.
As some people have pointed out, both UDP and TCP have their advantages. Note though, that for some applications you don't want retransmission at all! What's the point in having part of an audio stream retransmitted, or a video stream for that matter? It only makes things worse.
An excellent example comes from my own experience. Years ago we built a system that needed to synchronize system clocks between a server (hooked up to an atomic clock) and a bunch of workstations (I know about NTP, it was just too complicated for our humble needs). The server would broadcast the time over UDP every 30 seconds, and the workstations would synchronize their system clocks. This is a typical example where you don't want retransmission of lost packets, since the data (i.e., the system time) has become invalid in the mean time. Better to wait for the next update, since the system clocks will drift only microseconds in 30 seconds anyway.
Before implementing this, I sort of tested UDP reliability. I was warned about dropped packets, corrupted packets and packets delivered out of sequence. The test consisted of pumping out as many packets as possible, and see what happens. I never ever saw a single corrupted packet, or a packet delivered out of sequence! The only errors I could force were dropped packets, basically by overflowing the socket buffers on the receiving end. This test brought the network (10 Mb/s Ethernet LAN) completely to it's knees, by the way (got me the honorary title of "the network killer"). Millions and millions of packets sent, only dropped packets, never anything else.
Now, this was an isolated LAN (more or less) without crazy geeks downloading DivX movies, but the hardware wasn't all that spectacular either (SparcStation 10 server, 64MB RAM, SparcStation 5 workstations, 16MB RAM -- no typo!).
I ran some more tests with more 'normal' network loads, and I never, ever, detected a single problem.
So, your mileage may vary, but I think that problems with UDP typically would happen under circumstances (i.e., severe network congestion)that would also affect TCP.
Silly idea: you could use UDP with Forward Error Correction if your data is important. Plenty of textbooks about coding theory that explain the theory behind it, and how to design your customized error-correcting code. As long as you stay within the Shannon limit (i.e. don't try to exceed your channel capacity), you can make the error probability arbitrarily low. Doesn't help with disconnected cables an the like, since your channel capacity is zero then... Oh well, you can't win...
That's all very interesting, and I mostly agree with it.
However, there is one thing about a space station that everyone seems to be missing, and that is the absence of gravity. Studying physical, chemical and biological processes in such an environment has a tremendous potential payback, both scientifically and economically (e.g., producing extremely pure crystals, pharmaceutical applications, etc.)
Also, a space station allows us to study the effects of zero gravity on the human body. Could be useful when using the space station as a stepping stone.
Again, I basically agree with what you are saying. However, consider that all these ambitious colonization plans are going to be much more expensive than the ISS. A space station that (hopefully) is a huge success could pave the way (politically and in terms of budget allocation) for greater things.
This reminds me of the joke: "only in America do people order a double cheeseburger with large fries and a Diet Coke". Wouldn't it be wiser to cut caloric intake in other areas than sugar? Or drink fruit juice, or water for that matter...
Hmm, that's interesting, but I don't get it. Isn't stomach acid just a hydrogen chloride solution (i.e HCl)? I'm going out on a limb here, but I'm guessing that the concentration of Cl- in your stomach would be much higher than 1 ppm? So, how would ingesting a 1ppm Cl- solution hurt you?
Well, I actually had read that ("Supposing", etc.). I didn't want to critcize the original post unfairly. My point was that everybody seems to accept blindly that one country could not afford a Mars mission, and I was merely challenging that. The original (hypothetical) example is interesting, and I agree that at such costs it probably would not be a wise thing to do. However, the hypothetical example is orders of magnitude larger than a realistic figure.
Isn't the fact that no single nation on Earth can afford to develop a Mars mission a strong indication that it is massively impractical?
Says who?? That's the part I don't understand. $20 billion is a lot of money to you and me, but not to a lot of countries. The US can afford to build $5 billion submarines (and $200 million fighter planes). The US can afford to build a $60 billion missile defense that has a snowball's chance in hell of working. The JSF program is going to cost anywhere between $200 billion and $1 trillion. Granted, the cost are going to be distributed over many years, but you could do that with a Mars mission as well.
Now, let's not point the finger at the US alone. Many European countries (or Japan) could actually afford a Mars mission, if they really wanted to. Maybe the Russians would have trouble financing it, but if they don't need hard currency (i.e. if they could pay for it in rubles), they might just pull it off.
What is lacking is the political will. Like many posters pointed out, in the 60s there was a prestige aspect to the moon race (cold war, JFK, etc.). We're in a different situation right now, it is hard to convince the public that this is a good idea, especially since the payoff is going to be mostly scientific in nature.
...but it would take 5% of the world's GDP for 10 years...
Err, no, not even close to that. Let's look at some CIA data for the GDP of a few countries:
I could go on and on. Remember that these are annual numbers. My point is that even small countries could fund this, given the political will. The US or Europe could easily pay for it by themselves. $20 billion is just a drop in the bucket.
Absolutely agree. Example: say that after filling out dozens of registrations truthfully, some sophisticated algorithm figures out that I'm a nerd who likes to overclock home built PCs. So, they send me targeted spam (rather than the get rich schemes and buy Viagra online junk), inviting me to buy silent case fans and water cooling systems. Guess what? I already know where to buy those. Like you say, I don't see how this information is worth a lot of money. Yeah, it's cheaper to send electronic junk mail than to send paper junk mail. It's also easier to throw out.
This is something that already happened in the Major League Baseball online All-star ballot voting (voting is closed now).
Of course, this can be defeated by a script that analyzes all images on a form and does character recognition on the images. Not trivial, but it should be feasible.
Then of course, registration sites could present an image and ask you to identify it as a) Britney Spears b) the Space Shuttle c) Winnie-the-Pooh or d) Regis Philbin.
And then automated scripts could just pick one at random, and one in every 4 attempts will succeed, and then registration sites could ask you to type in the correct answer ('Brittney Speers', oops, access denied), and then...never mind...
On the other hand, I thanked God they didn't pick the hideous looking Boeing contraption. No self respecting fighter pilot would want to be seen in that.
You're hitting the nail on the head! That's why they should have chosen the Boeing design! It's supposed to be stealthy, remember? Every fighter pilot would be so embarassed that they would have found a way to becom reallt invisible...
You're absolutely right, you can't compare the two, the JSF is designed not to be detected in the first place. An even more extreme example: the F-117 does not even have a cannon (nor missiles), so it's completely defenseless *if detected*. The F-designation is a joke, the F-117 is not a fighter plane in any sense of the word.
I never really understood the STOVL argument, since the number of STOVL versions built for the Marines and the Royal Navy is quite small when compared to the conventional versions.
Anyway, one of the possible uses for the huge lift fan could be to utilize it as a 1 MegaWatt electrical generator and build a very powerful jamming version (EF-35?) with it. This was suggested in an article in Aviation Week & Space Technology...
Correct. This has been brought up many times during the Concept Demonstartion Phase of the JSF program. Basically, Boeing cannot be expected to invest in their tactical fighter business any more. So when the JSF is replaced (many, many years from now), there is a reasonable chance that the Pentagon will be at the mercy of LM. Unless the JSF production is somehow shared with Boeing and possibly Northrop-Grumman. But that scenario has always been denied...
Big part of the JSF program is affordability. The engine alone costs something like $8 million, so do the math on a $28 million dollar plane (that's 1994 dollars for the Air Force version, I'll admit. The other versions are a little pricier). Also, I can imagine that a single-engine plane would in principle be stealthier (stealth aspects are not just radar cross-section, it's also infrared signature and noise).
Slashdot Mirror
Browse the jobs yourself if you don't believe me. 98% of them say "US Citizen or Green Card holders only"
That is very interesting. I thought that that was illegal, except for defense jobs. Job discrimination on the basis of immigration status is not allowed. Or maybe that has changed...
Require extremely hard exams to be passed before you can be considered an engineer
That's what college exams are for. I don't know about the US, but in Europe you can't get an engineering degree if you're stupid.
H1B's have to have a Bachelor's degree or equivalent.
All very true. One additional thing: the H1B worker has to have a Bachelor's Degree or equivalent. "Equivalent" could be 10 yrs work experience or something like that, but things are a lot easier if you do have the college degree.
I hope they're not using normal glass, which is technically a liquid. Look at windows in colonial houses; their bottom is thicker than their top.
True, but:
- modern day glass may have better properties than colonial glass
- this thing is going to be put on a satellite orbiting the earth. The zero gravity should help that problem.
Come to think of it: it may be a bigger challenge to keep the satellite's orbit stable for 50,000 years.
I wonder why they picked 50,000 years.
Nothing lasts forever, not even glass discs. Entropy and all that, also causes your razor blades to become dull by themselves. I guess they think the glass disc would still be readable after 50K years.
There is a great SF story by Gregory Benford
Spoiler Warning
Don't read on if you think you want to read the story. The following spoils it a bit. However, it is essential to illustrate my point.
.
.
.
.
.
.
.
The story is about retrieving information from pottery. The idea is to restore the sounds that were around when people were making pottery centuries ago. I read somewhere that this was based on actual serious research.
Anyhow, the scientists succeed, but are disappointed by what they can retrieve: middle-agers shouting warnings into the pot not to walk on this and this guy's land, because the sheep will get sick, and other nonsense like that.
At the same time some other scientists are preparing a time capsule for the benefit of future generations. The conclusion of the story is: "what makes us think we are doing a better job than the people from the middle ages?"
I guess the same applies here: even if we would filter out all the crap ("l33t hax0rz in sp33z!"), are people really going to give a damn in 50K years?
Scientists already think that we pretty much know most of what there is to know...
Ah yes, I think Stephen Hawking is one of them. Well, I remember reading this statement made by Lord Kelvin around 1900 or so, where he said the same thing: "Physics is more or less complete. There are only two small problems left to be solved". Or something like that, forgive me for not quoting literally. Anyhow, one of the small problems led to the theory of relativity, the other to quantum mechanics.
Hah, OK, I've found it. It was called 'xntp', where the 'x' apparently stood for 'experimental', rather than 'X' as in 'X-server'.
Ok, you got me. I made a mistake. This was 8 years ago, we looked at something which sounded similar to 'NTP'. I can't remember what it was called exactly any more, and I'm not gonna waste more time on it. All I know is that we analyzed the problem, evaluated what was available, and made a decision.
That's an excellent point. I sort of meant to hint at that, but I guess I should have put more emphasis on our particular setup.
Anyway, it's a relevant point to the original question: it's not just the applications and network load that matter, it's also the network topology.
Whatever. All I can remember that in those days we looked at NTP (or maybe it was NNTP??), and did not like the idea of going through and possibly maintaining 40,000 lines of C (that's the way it was in '94, or at least that's how I remember it).
Our "homegrown NTP" as you call it wasn't even close to that. All we needed was a simple way to keep system clocks in line, with an accuracy of a few tenths of a second. We accomplished this in a few dozen lines of C++ (a generic message broadcasting mechanism over UDP was already implemented).
In hindsight you can always question decisions like that, but bottom line is that we had a simple problem, and we fixed it with a simple solution.
And the software (control system for rocket launches) has been in operational use since 1996, without any major problems, thank you.
As some people have pointed out, both UDP and TCP have their advantages. Note though, that for some applications you don't want retransmission at all! What's the point in having part of an audio stream retransmitted, or a video stream for that matter? It only makes things worse.
An excellent example comes from my own experience. Years ago we built a system that needed to synchronize system clocks between a server (hooked up to an atomic clock) and a bunch of workstations (I know about NTP, it was just too complicated for our humble needs). The server would broadcast the time over UDP every 30 seconds, and the workstations would synchronize their system clocks. This is a typical example where you don't want retransmission of lost packets, since the data (i.e., the system time) has become invalid in the mean time. Better to wait for the next update, since the system clocks will drift only microseconds in 30 seconds anyway.
Before implementing this, I sort of tested UDP reliability. I was warned about dropped packets, corrupted packets and packets delivered out of sequence. The test consisted of pumping out as many packets as possible, and see what happens. I never ever saw a single corrupted packet, or a packet delivered out of sequence! The only errors I could force were dropped packets, basically by overflowing the socket buffers on the receiving end. This test brought the network (10 Mb/s Ethernet LAN) completely to it's knees, by the way (got me the honorary title of "the network killer"). Millions and millions of packets sent, only dropped packets, never anything else.
Now, this was an isolated LAN (more or less) without crazy geeks downloading DivX movies, but the hardware wasn't all that spectacular either (SparcStation 10 server, 64MB RAM, SparcStation 5 workstations, 16MB RAM -- no typo!).
I ran some more tests with more 'normal' network loads, and I never, ever, detected a single problem.
So, your mileage may vary, but I think that problems with UDP typically would happen under circumstances (i.e., severe network congestion)that would also affect TCP.
Silly idea: you could use UDP with Forward Error Correction if your data is important. Plenty of textbooks about coding theory that explain the theory behind it, and how to design your customized error-correcting code. As long as you stay within the Shannon limit (i.e. don't try to exceed your channel capacity), you can make the error probability arbitrarily low. Doesn't help with disconnected cables an the like, since your channel capacity is zero then... Oh well, you can't win...
That's all very interesting, and I mostly agree with it.
However, there is one thing about a space station that everyone seems to be missing, and that is the absence of gravity. Studying physical, chemical and biological processes in such an environment has a tremendous potential payback, both scientifically and economically (e.g., producing extremely pure crystals, pharmaceutical applications, etc.)
Also, a space station allows us to study the effects of zero gravity on the human body. Could be useful when using the space station as a stepping stone.
Again, I basically agree with what you are saying. However, consider that all these ambitious colonization plans are going to be much more expensive than the ISS. A space station that (hopefully) is a huge success could pave the way (politically and in terms of budget allocation) for greater things.
This reminds me of the joke: "only in America do people order a double cheeseburger with large fries and a Diet Coke".
Wouldn't it be wiser to cut caloric intake in other areas than sugar? Or drink fruit juice, or water for that matter...
Hmm, that's interesting, but I don't get it. Isn't stomach acid just a hydrogen chloride solution (i.e HCl)? I'm going out on a limb here, but I'm guessing that the concentration of Cl- in your stomach would be much higher than 1 ppm? So, how would ingesting a 1ppm Cl- solution hurt you?
Well, I actually had read that ("Supposing", etc.). I didn't want to critcize the original post unfairly. My point was that everybody seems to accept blindly that one country could not afford a Mars mission, and I was merely challenging that. The original (hypothetical) example is interesting, and I agree that at such costs it probably would not be a wise thing to do. However, the hypothetical example is orders of magnitude larger than a realistic figure.
Isn't the fact that no single nation on Earth can afford to develop a Mars mission a strong indication that it is massively impractical?
...but it would take 5% of the world's GDP for 10 years...
:
Says who?? That's the part I don't understand. $20 billion is a lot of money to you and me, but not to a lot of countries. The US can afford to build $5 billion submarines (and $200 million fighter planes). The US can afford to build a $60 billion missile defense that has a snowball's chance in hell of working. The JSF program is going to cost anywhere between $200 billion and $1 trillion. Granted, the cost are going to be distributed over many years, but you could do that with a Mars mission as well.
Now, let's not point the finger at the US alone. Many European countries (or Japan) could actually afford a Mars mission, if they really wanted to. Maybe the Russians would have trouble financing it, but if they don't need hard currency (i.e. if they could pay for it in rubles), they might just pull it off.
What is lacking is the political will. Like many posters pointed out, in the 60s there was a prestige aspect to the moon race (cold war, JFK, etc.). We're in a different situation right now, it is hard to convince the public that this is a good idea, especially since the payoff is going to be mostly scientific in nature.
Err, no, not even close to that. Let's look at some CIA data for the GDP of a few countries
USA: $9.963 trillion
Japan: $3.15 trillion
South Korea: $764.6 billion
Russia: $1.12 trillion
United Kingdom: $1.36 trillion
France: $1.448 trillion
Netherlands: $388.4 billion
Germany: $1.936 trillion
Australia: $445.8 billion
I could go on and on. Remember that these are annual numbers. My point is that even small countries could fund this, given the political will. The US or Europe could easily pay for it by themselves. $20 billion is just a drop in the bucket.
Absolutely agree. Example: say that after filling out dozens of registrations truthfully, some sophisticated algorithm figures out that I'm a nerd who likes to overclock home built PCs. So, they send me targeted spam (rather than the get rich schemes and buy Viagra online junk), inviting me to buy silent case fans and water cooling systems. Guess what? I already know where to buy those. Like you say, I don't see how this information is worth a lot of money. Yeah, it's cheaper to send electronic junk mail than to send paper junk mail. It's also easier to throw out.
This is something that already happened in the Major League Baseball online All-star ballot voting (voting is closed now).
Of course, this can be defeated by a script that analyzes all images on a form and does character recognition on the images. Not trivial, but it should be feasible.
Then of course, registration sites could present an image and ask you to identify it as a) Britney Spears b) the Space Shuttle c) Winnie-the-Pooh or d) Regis Philbin.
And then automated scripts could just pick one at random, and one in every 4 attempts will succeed, and then registration sites could ask you to type in the correct answer ('Brittney Speers', oops, access denied), and then...never mind...
On the other hand, I thanked God they didn't pick the hideous looking Boeing contraption. No self respecting fighter pilot would want to be seen in that.
You're hitting the nail on the head! That's why they should have chosen the Boeing design! It's supposed to be stealthy, remember? Every fighter pilot would be so embarassed that they would have found a way to becom reallt invisible...
You're absolutely right, you can't compare the two, the JSF is designed not to be detected in the first place. An even more extreme example: the F-117 does not even have a cannon (nor missiles), so it's completely defenseless *if detected*. The F-designation is a joke, the F-117 is not a fighter plane in any sense of the word.
I never really understood the STOVL argument, since the number of STOVL versions built for the Marines and the Royal Navy is quite small when compared to the conventional versions.
Anyway, one of the possible uses for the huge lift fan could be to utilize it as a 1 MegaWatt electrical generator and build a very powerful jamming version (EF-35?) with it. This was suggested in an article in Aviation Week & Space Technology...
Correct. This has been brought up many times during the Concept Demonstartion Phase of the JSF program. Basically, Boeing cannot be expected to invest in their tactical fighter business any more. So when the JSF is replaced (many, many years from now), there is a reasonable chance that the Pentagon will be at the mercy of LM. Unless the JSF production is somehow shared with Boeing and possibly Northrop-Grumman. But that scenario has always been denied...
Correct, it's an F119 derivative. And the F22 has two engines, by the way...
Big part of the JSF program is affordability. The engine alone costs something like $8 million, so do the math on a $28 million dollar plane (that's 1994 dollars for the Air Force version, I'll admit. The other versions are a little pricier).
Also, I can imagine that a single-engine plane would in principle be stealthier (stealth aspects are not just radar cross-section, it's also infrared signature and noise).