Aah yes, you are correct from a trust point of view. However, from a trust point of view, how can you really ever be truly sure of whom you are talking? Impersonation is always a problem, and then there's the issue of double agents and infiltrators. Then there's the whole sci-fi aspect like in the movie Face Off.
Which it's worth noting, was resolved in that movie the same way - by using the common body of shared secrets to establish who was who.
The only way to improve it would be to use the Socialist Millionaire means to allow them to establish that they have a shared secret without divulging what it is.
But this is true of all encrypted mechanisms and is the nature of establishing trust. There's no technological solution for it, other then to have actually met or otherwise established that who you are talking to holds a certain shared secret.
The idea that "direct point to point" channels fixes it is foolish - without a shared secret, you can't be sure the channel is point to point to who you think it is, and the trouble and effort to establish it is is just a very convoluted way of establishing a shared secret.
Actually, that's not correct. You do not need even one guaranteed interaction in order to establish an encrypted channel. Diffie-Hellman key exchange is pretty secure, as long as your encryption protocol is not broken. Whatever the circumstances, you need trusted endpoints, and you need a viable encryption protocol. You need those two. Not two out of a set of three, which include those. Untrusted endpoints means you're open to side channel attacks or simple bugging. Even if you have bulletproof protocols and 100% trusted interaction, it's no help if your endpoints have keyloggers sending their data to Eve.
Diffie-Hellman just lets you establish session keys. It doesn't let you establish trust - you have no idea if the remote party is who you think they are, unless you communicate out-of-band or from a shared knowledge base.
Trust establishment can be very simple and only needs to be done once if you protect your system, but it can't be done technologically - it's all about establishing a causal chain from someone else's brain to whatever the technology exposes.
Radio can be point-to-point. You can't exactly intercept an airborne signal and try to relay it without building a shield large enough to fully encompass the sender. Something that they would readily be aware of.
This seems irrelevant though: provided two parties have some type of initial shared but not public knowledge, modern crypto can give you a reliably secure channel despite any number of intermediary parties.
Almost everyone gets it wrong, and it's the most annoying to fix after the fact. You want whatever room you're in bright - very bright, and illuminated uniformly. If you're putting in shelves or anything that occludes light, plan to have lights attached to it. You'll find yourself *much* happier later.
Sooner or later, even if we find primitive life, we should start thinking about what can be done with the planet, even if it takes 1000 years to get something to live there.
It wouldn't. The main problem is the lack of liquid water, the second problem is the low atmospheric pressure, and the third is the low level of sunlight. A couple of ice asteroids would take care of the lack of water and atmosphere at the same time; after that, the question is how to prevent the newfound water from being stripped away by solar wind. While it would take millenias to happen, you can't exactly keep on asteroid bombing an inhabited planet and expect it to remain inhabited. So, Mars is habitable in a reasonable short time; but for long-term habitability, we would need some way to restart its core and magnetic field.
Realistically Mars is a poor choice for terraforming because of it's atmosphere and sunlight. A far better choice is Venus, which has similar dimensions, mass and gravity as Earth, and is clearly capable of maintaining an atmosphere (it's single biggest problem at the moment). It's slightly closer to the sun, but not significantly - it's current surface temperature is entirely due to it's runaway greenhouse effect.
The atmosphere on Venus, terraforming wise, is almost certainly something we can work with and is mostly carbon dioxide. If we could add enough water to the planet to form major oceans, and maybe in the process shear some of the atmosphere off into space from the comet impacts we use to do it, then chances are we'd end up with an environment which Earth microbes could thrive in - and convert that CO2 into a breathable oxygen atmosphere, and breakdown the acidic environment.
It is conceivable that some parents do not want their children to grow up to be engineers, so I fail to see your point
Did you mean "grew up without any advertisement-caused brain damage, and could thus become a successful engineer"?
No parents should be deluding themselves to think they can somehow decide what their children will grow up to be. You give them a lot of stuff and see what they like, and struggle to teach them all the stuff they'll need.
Not really. An explosion - i.e. a detonation - is a very specific type of event with very specific and disasterous consequences. A pressure release is not necessarily a detonation.
Obviously SpaceX wants to achieve man-rating so that they can launch and return personnel in addition to the cargo runs they're currently beginning. I'm curious as to how this moderate malfunction will impact the rest of the program.
Bearing in mind, of course, the deaths of Chaffee, Grissom, and White in the Apollo 1 accident, the launch-time engine failure and later unrelated catastrophic failure for Apollo 13, the Challenger disaster, and the Columbia disaster, it's difficult to call SpaceX's anomaly as being any worse than those. If SpaceX manages a series of cargo deliveries without any loss of the capsule or with complete success on delivery then even with this anomaly they're arguably no worse off than any of the previous space programs were, as far as reliability and safety goes.
The important thing is whether they can successfully determine what actually happened, and why it happened (i.e. replicate the malfunction on a test bed engine). This was the thing Feynman was most critical of NASA for post-Challenger - that the whole disaster was caused by this faulty assumption about engineering risks on the O-Ring seals (i.e. the seals were getting eroded by exhaust during launch, but the question posed was "is this dangerous" not "why is this happening" - the former being foolish since the system was not designed to cope with this, and it's true cause was unknown).
It's a triumph that the launch still succeeded, but having averted an unforeseen consequence the only safe thing to do is make sure it's both forseen and mitigated in the future.
I'm pretty sure it actually has in a bunch of different Tokamak devices, just not sustainably (and with no conversion). That said you are right in that finding out how to do ignition with inertial confinement is kind of a big deal, since we can take that data and say - for example - this is the exact specifications we need to aim for to build ourselves a fusion powered rocket engine.
There are at least three. The "Polywell" (which uses a form of inertial electrostatic confinement fusion) is yet another approach.
There's also some ways to generate extremely inefficient table top fusion (eg, the Farnsworth fusor). Some day we might figure out how to make those efficient enough to generate power.
Farnsworth fusor's are physically due to losses due to material escaping confinement or slamming into the electrical grid in the middle. No matter how you tweak one, the Farnsworth design won't make energy - too many loss processes. Great for desktop neutrons though.
The Polywell was designed to fix the problems with Farnsworth fusor's by replacing the physical grid with a virtual one composed of focussed electrons. The problem is, the guy who did a lot of the work didn't keep great lab notes (and is now dead), so whether it can work or not is unknown - DARPA are funding some work on it though. The problem is you can't just build a big one - there's a lot of design and engineering and theory that needs to be developed to figure out what exactly we'd want to build, and whether that thing is likely to work (Polywell's have their own set of loss processes and competing issues which need to be balanced).
It really does need to stuck under the purview of the department of defense. I mean DARPA has had a long term interest in cold-fusion, simply because if it's at all possible they want to know about it - just in case. You'd think the benefits of hot fusion to powering submarines and aircraft carriers would warrant similar interest.
Depends how long you're thinking. In the long run it's still fusion, but one has to imagine that between asteroid mining and the cheap launch capability we might gain from fusion-powered rockets, we could assemble a Dyson-sphere like construct of satellites to harvest power off the big reactor above us.
There's also the significant expectation that practical fusion reactors are likely to lead to more capable fusion processes once we have actually built applied, working examples of the technology. While it's not known, I would be amazed if once D-T fusion was viable, that was the end game of man-made fusion power (i.e. if it was not at all possible to step it up to D-D).
A world where the US doesn't maintain an overwhelming deterrent to forces which espouse principles and ideals counter to those of freedom and liberal democracy is not a pretty place
US did not maintain an overwhelming deterrent to opposing forces for a good half of 20th century - it was at parity. The world did not collapse.
Military technology was also vastly different, and the period leading up to the establishment of the nuclear deterrent saw 2 of the bloodiest and largest wars ever fought occur.
To think that we could happily go back to that age is to be naive.
There was the article on/. a while back where MIT was answering questions about fusion and it was pointed out that based on the historical cutting of fusion research investment, fusion power is about $80 billion away, and has always been 25 years away because it's budget has been progressively cut.
The NIF is part of the military essentially. While it has the side-benefit of allowing us to investigate inertial confined fusion, I thought the whole point of places like that was as a way to test nuclear weapons without actually setting them off?
Well in Zero-G you have issues like vapor dispersion of fluids. The human blink reflex is pretty good on Earth with large droplets and gravity - in space a drop let floats around until it gets broken up into smaller things, so I imagine it's a serious concern that reasonably heavy particulates which normally aren't much of a problem would just be dispersed in the normal atmosphere.
This isn't even about the lack of surgery, but an unknown increase in risk for others, should one take place. Rather than identifying the risk and mitigating it (is it only from infected blood touching the bulkheads?, or microscopic blood pieces being respirated?), the solution is to spend billions eliminating the risk. If the "solution" was as simple as put everyone in "disposable" surgery suits, then after the surgery, everyone goes on a spacewalk while the inside is sterilized with high-power UV or a toxic aerosol, would that be cheaper than the surgery-box?
Then do the work to get that certified for space flight. Cheaper, easier, more reliable, and available now, with no development cost.
Unexpectedly respirated blood or infectious fluids is a pretty serious problem. Most of the worst diseases you can get are the result of normally fairly harmless bacteria getting into unusual places in the body.
What if the rotational section breaks down and you need to perform surgery? These two events are pretty well connected to each other - a potential mechanical failure in the rotational section, even repairable, might also cause an injured crewman. You would want to be able to do surgery or minor surgical procedures in zero or low gravity, because you might not be able to repair the rotation for some time.
Exactly. There's enormous potential applications for something like this on Earth. It's hardly a "dead end" and having additional tools available to us in Zero-G is hardly a bad thing.
Except that said photon could also be part of the system. Or more importantly - the alive and dead physicist could do other things like unlock the box and get out of it, becoming a very much alive physicist who has just successfully collapsed their own quantum state.
Slashdot Mirror
Aah yes, you are correct from a trust point of view. However, from a trust point of view, how can you really ever be truly sure of whom you are talking? Impersonation is always a problem, and then there's the issue of double agents and infiltrators. Then there's the whole sci-fi aspect like in the movie Face Off.
Which it's worth noting, was resolved in that movie the same way - by using the common body of shared secrets to establish who was who.
The only way to improve it would be to use the Socialist Millionaire means to allow them to establish that they have a shared secret without divulging what it is.
But this is true of all encrypted mechanisms and is the nature of establishing trust. There's no technological solution for it, other then to have actually met or otherwise established that who you are talking to holds a certain shared secret.
The idea that "direct point to point" channels fixes it is foolish - without a shared secret, you can't be sure the channel is point to point to who you think it is, and the trouble and effort to establish it is is just a very convoluted way of establishing a shared secret.
Actually, that's not correct. You do not need even one guaranteed interaction in order to establish an encrypted channel. Diffie-Hellman key exchange is pretty secure, as long as your encryption protocol is not broken.
Whatever the circumstances, you need trusted endpoints, and you need a viable encryption protocol. You need those two. Not two out of a set of three, which include those. Untrusted endpoints means you're open to side channel attacks or simple bugging. Even if you have bulletproof protocols and 100% trusted interaction, it's no help if your endpoints have keyloggers sending their data to Eve.
Diffie-Hellman just lets you establish session keys. It doesn't let you establish trust - you have no idea if the remote party is who you think they are, unless you communicate out-of-band or from a shared knowledge base.
Trust establishment can be very simple and only needs to be done once if you protect your system, but it can't be done technologically - it's all about establishing a causal chain from someone else's brain to whatever the technology exposes.
Radio can be point-to-point. You can't exactly intercept an airborne signal and try to relay it without building a shield large enough to fully encompass the sender. Something that they would readily be aware of.
This seems irrelevant though: provided two parties have some type of initial shared but not public knowledge, modern crypto can give you a reliably secure channel despite any number of intermediary parties.
I cannot stress lighting enough.
Almost everyone gets it wrong, and it's the most annoying to fix after the fact. You want whatever room you're in bright - very bright, and illuminated uniformly. If you're putting in shelves or anything that occludes light, plan to have lights attached to it. You'll find yourself *much* happier later.
It wouldn't. The main problem is the lack of liquid water, the second problem is the low atmospheric pressure, and the third is the low level of sunlight. A couple of ice asteroids would take care of the lack of water and atmosphere at the same time; after that, the question is how to prevent the newfound water from being stripped away by solar wind. While it would take millenias to happen, you can't exactly keep on asteroid bombing an inhabited planet and expect it to remain inhabited. So, Mars is habitable in a reasonable short time; but for long-term habitability, we would need some way to restart its core and magnetic field.
Realistically Mars is a poor choice for terraforming because of it's atmosphere and sunlight. A far better choice is Venus, which has similar dimensions, mass and gravity as Earth, and is clearly capable of maintaining an atmosphere (it's single biggest problem at the moment). It's slightly closer to the sun, but not significantly - it's current surface temperature is entirely due to it's runaway greenhouse effect.
The atmosphere on Venus, terraforming wise, is almost certainly something we can work with and is mostly carbon dioxide. If we could add enough water to the planet to form major oceans, and maybe in the process shear some of the atmosphere off into space from the comet impacts we use to do it, then chances are we'd end up with an environment which Earth microbes could thrive in - and convert that CO2 into a breathable oxygen atmosphere, and breakdown the acidic environment.
"Short order" is still a few hundred million years.
If we're capable of creating an atmosphere via terraforming, we are easily capable of replacing losses over that type of timescale.
Grew up to become an engineer.
It is conceivable that some parents do not want their children to grow up to be engineers, so I fail to see your point
Did you mean "grew up without any advertisement-caused brain damage, and could thus become a successful engineer"?
No parents should be deluding themselves to think they can somehow decide what their children will grow up to be. You give them a lot of stuff and see what they like, and struggle to teach them all the stuff they'll need.
Not really. An explosion - i.e. a detonation - is a very specific type of event with very specific and disasterous consequences. A pressure release is not necessarily a detonation.
I was under the impression that SpaceX had poached a ton of former NASA or support company people?
Obviously SpaceX wants to achieve man-rating so that they can launch and return personnel in addition to the cargo runs they're currently beginning. I'm curious as to how this moderate malfunction will impact the rest of the program.
Bearing in mind, of course, the deaths of Chaffee, Grissom, and White in the Apollo 1 accident, the launch-time engine failure and later unrelated catastrophic failure for Apollo 13, the Challenger disaster, and the Columbia disaster, it's difficult to call SpaceX's anomaly as being any worse than those. If SpaceX manages a series of cargo deliveries without any loss of the capsule or with complete success on delivery then even with this anomaly they're arguably no worse off than any of the previous space programs were, as far as reliability and safety goes.
The important thing is whether they can successfully determine what actually happened, and why it happened (i.e. replicate the malfunction on a test bed engine). This was the thing Feynman was most critical of NASA for post-Challenger - that the whole disaster was caused by this faulty assumption about engineering risks on the O-Ring seals (i.e. the seals were getting eroded by exhaust during launch, but the question posed was "is this dangerous" not "why is this happening" - the former being foolish since the system was not designed to cope with this, and it's true cause was unknown).
It's a triumph that the launch still succeeded, but having averted an unforeseen consequence the only safe thing to do is make sure it's both forseen and mitigated in the future.
I'm pretty sure it actually has in a bunch of different Tokamak devices, just not sustainably (and with no conversion). That said you are right in that finding out how to do ignition with inertial confinement is kind of a big deal, since we can take that data and say - for example - this is the exact specifications we need to aim for to build ourselves a fusion powered rocket engine.
There are two proposed approaches
There are at least three. The "Polywell" (which uses a form of inertial electrostatic confinement fusion) is yet another approach.
There's also some ways to generate extremely inefficient table top fusion (eg, the Farnsworth fusor). Some day we might figure out how to make those efficient enough to generate power.
Farnsworth fusor's are physically due to losses due to material escaping confinement or slamming into the electrical grid in the middle. No matter how you tweak one, the Farnsworth design won't make energy - too many loss processes. Great for desktop neutrons though.
The Polywell was designed to fix the problems with Farnsworth fusor's by replacing the physical grid with a virtual one composed of focussed electrons. The problem is, the guy who did a lot of the work didn't keep great lab notes (and is now dead), so whether it can work or not is unknown - DARPA are funding some work on it though. The problem is you can't just build a big one - there's a lot of design and engineering and theory that needs to be developed to figure out what exactly we'd want to build, and whether that thing is likely to work (Polywell's have their own set of loss processes and competing issues which need to be balanced).
The Z-machine, even if it does produce fusion, is hardly an easily repeatable or scalable device itself either.
It really does need to stuck under the purview of the department of defense. I mean DARPA has had a long term interest in cold-fusion, simply because if it's at all possible they want to know about it - just in case. You'd think the benefits of hot fusion to powering submarines and aircraft carriers would warrant similar interest.
Depends how long you're thinking. In the long run it's still fusion, but one has to imagine that between asteroid mining and the cheap launch capability we might gain from fusion-powered rockets, we could assemble a Dyson-sphere like construct of satellites to harvest power off the big reactor above us.
There's also the significant expectation that practical fusion reactors are likely to lead to more capable fusion processes once we have actually built applied, working examples of the technology. While it's not known, I would be amazed if once D-T fusion was viable, that was the end game of man-made fusion power (i.e. if it was not at all possible to step it up to D-D).
A world where the US doesn't maintain an overwhelming deterrent to forces which espouse principles and ideals counter to those of freedom and liberal democracy is not a pretty place
US did not maintain an overwhelming deterrent to opposing forces for a good half of 20th century - it was at parity. The world did not collapse.
Military technology was also vastly different, and the period leading up to the establishment of the nuclear deterrent saw 2 of the bloodiest and largest wars ever fought occur.
To think that we could happily go back to that age is to be naive.
There was the article on /. a while back where MIT was answering questions about fusion and it was pointed out that based on the historical cutting of fusion research investment, fusion power is about $80 billion away, and has always been 25 years away because it's budget has been progressively cut.
The NIF is part of the military essentially. While it has the side-benefit of allowing us to investigate inertial confined fusion, I thought the whole point of places like that was as a way to test nuclear weapons without actually setting them off?
Well in Zero-G you have issues like vapor dispersion of fluids. The human blink reflex is pretty good on Earth with large droplets and gravity - in space a drop let floats around until it gets broken up into smaller things, so I imagine it's a serious concern that reasonably heavy particulates which normally aren't much of a problem would just be dispersed in the normal atmosphere.
This isn't even about the lack of surgery, but an unknown increase in risk for others, should one take place. Rather than identifying the risk and mitigating it (is it only from infected blood touching the bulkheads?, or microscopic blood pieces being respirated?), the solution is to spend billions eliminating the risk. If the "solution" was as simple as put everyone in "disposable" surgery suits, then after the surgery, everyone goes on a spacewalk while the inside is sterilized with high-power UV or a toxic aerosol, would that be cheaper than the surgery-box?
Then do the work to get that certified for space flight. Cheaper, easier, more reliable, and available now, with no development cost.
Unexpectedly respirated blood or infectious fluids is a pretty serious problem. Most of the worst diseases you can get are the result of normally fairly harmless bacteria getting into unusual places in the body.
What if the rotational section breaks down and you need to perform surgery? These two events are pretty well connected to each other - a potential mechanical failure in the rotational section, even repairable, might also cause an injured crewman. You would want to be able to do surgery or minor surgical procedures in zero or low gravity, because you might not be able to repair the rotation for some time.
Exactly. There's enormous potential applications for something like this on Earth. It's hardly a "dead end" and having additional tools available to us in Zero-G is hardly a bad thing.
Except that said photon could also be part of the system. Or more importantly - the alive and dead physicist could do other things like unlock the box and get out of it, becoming a very much alive physicist who has just successfully collapsed their own quantum state.