Re:Wait... so you're telling me...
on
A New Ice Age?
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· Score: 2, Interesting
Actually, an interesting thing I found out the other day - several hundred years ago, in post-medieval europe, one of the causes of death was "planet". This is what happened when a person died mysteriously when the planets were aligned in a particular way. It was interpreted as the planets having struck them down. So what did they really die of?
Forgive what may be an ignorant question - but how does having a moon slow down a planet's rotation? You mention angular momentum, but I have trouble seeing how that applies given that the moon and the planet are not connected (i.e. can't the moon and planet each have separate angular momentums? How does angular momentum of the moon get attached to the planet's angular momentum so that they act as a system?). I'm pretty curious how this works.
I think that ISPs could simply then start looking for seemingly random port probes by machine A on machine B, followed by machine B spewing gobs of data to machine A on a random port. That's the trick, make your protocol too good and it'll stand out because it's too random. If you ever actually talk to anyone who works at ISPs though, they generally just flag those customers with unbelievable upload/download ratios and then have a human look at their logs to see if they're violating the TOS (running a server, hosting warez, whatever).
First off, your assumption that they will use Proton rockets may be wrong - they may use a reconstructed Russian variant of a Saturn V, and launch everything in one or two trips. There's another post on this article that suggests alternatives to the Proton.
Secondly, I don't trust many numbers thrown around on/. without a reference, and that 1 million pounds for an expedition definitely sounds like a number out of thin air. Without looking at their designs, it's really impossible to speculate on the final weight/mass of the vehicle.
Finally, and perhaps most importantly, why go into orbit to assemble your vehicle? Why not launch it pre-assembled on a big-ass rocket (see pt. 1) and go straight for mars or whatever bodies you're using for a gravity assist trajectory? Going into orbit uses a lot of energy, and I really don't see the need for it. A lot of sci-fi involves orbital assemblies, but when you do the math it's not actually that practical...
All that being said however, I agree that I can't see this mission flying. It reeks of overly optimistic budgeting designed to secure enough venture capital to get some executives a fun, well paying job for a few years before the project dies in a sea of red ink.
IIRC, the exocet that struck the HMS Sheffield did detonate, but that was not the main problem. The problem was that the Type 42 Destroyer class used almost solid aluminium superstructures. In extremely high temperatures, aluminium can burn (just like magnesium, but even higher temps). When the ship was struck, it ignited the aluminium which then steadily burned. This is why you no longer see ships produced with all-aluminium superstructures any more.
Yeah, I thought the dance was pretty amazing - I had no idea that we'd come that far in robotics. However, I watched it a few times and if you focus on the feet, you realize that they're mostly just waving their arms, and their feet are making very small steps left, forward, turning, etc. The armwaving is considerably easier to manage in robotics, unless it's standing on one foot (notice that the robots didn't wave their arms much when they did that little demo of standing on one foot (mind you, I know plenty of humans that can't do that).
Still a pretty damn impressive show. The actuation in the arms was especially convincing. I'd like to see it in person actually.
Presumably it could be overwritten to obscure it whereas a watermark could not be removed without destroying the original data.
Actually, there is a method of removing watermarks. What you have to do is get multiple versions of the file - each with a different watermark (i.e. purchase the same song with different accounts multiple times). Then you take the files and average them. For every file you add to this process, the watermark becomes more obscured. Now, it might be impractical right now, but it is not difficult to change.
shit, that sounds even cooler - and it would actually be practical too! It'd be sweet to ride down the street on that and just watch the looks people give you...
yeah, but if we used a fractally patterned tread, the wheels would lock into the road and then you'd have a hard time going anywhere, regardless of the fact that you have an infinite road surface to drive on.:-)
That bike actually sounds pretty cool. Though it is ultimately more practical than this one, it still has a major drawback in that at certain times in a rotation (when there's a flat side down), square wheels will require ENOURMOUS amounts of torque to move forward and at others (when it's sitting on a point) it will require none at at. Devising a powertrain that can provide this kind of harmonically varying load given is another challenge that stands in the way of building a usable bike with square wheels.
Re:Talking about insanely short-sighted...
on
Weapons in Space
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· Score: 1
Actually, the famous physicist Heisenberg worked was the guy that the Nazis consulted on whether nuclear weapons were feasible. It has never been proven, but there is evidence to suggest that Heisenberg purposely fudged his calculations by introducing errors which are very elementary, and should have been recognized and fixed. This was primarily evident in his critical mass calculations, in which he used a plane of uranium, rather than a sphere, resulting in an enourmous, untransportable amount of uranium required to produce a fission explosion.
As well, the German program was retarded by their failure to realize that graphite was usable as a moderator. They thus invested enourmous energy and finances into heavy-water production, which is actually quite a technically difficult process.
This is also a technique commonly used in fruit farming. If a farmer is worried about a frost damaging his fruit, he can go around and spray water on all the fruit. When temperatures drop, the water freezes and the fruit doesn't. It also helps that ice is a pretty good insulator, so once it's frozen you now have effectively encased each fruit in an insulating shield. This is used regularly throughout the US, and I'd bet it's used around the world too.
He actually might have a future in competitive eating - I don't know anyone, even championship hotdog eaters, that has attempted to eat a 10-minute struggle!
Um, if you read the page you linked to, it says that the four test-launches of the N1 that they did were all miserable failures - maybe this also had something to do with their decision to kill the plans?
Angular momentum refers to the linear momentum of the probe times the radius from the sun at which it is orbiting.
As for the energy, It's actually pretty tricky to lose KE + PE in space - you either have to use engines (with expensive-to-launch fuel) or sophisticated aerobraking techniques and whatnot by making close passes to other planets. In fact, when this probe gets to Mercury, if i'm not mistaken, it will still have nearly the same energy (in terms of KE and PE).
In the scramjet reasearch buisiness, 10 seconds is an eternity. Most institutions who are researching this technology are universities and the like who don't have access to B-52s, rocket boosters, and the other equipment needed to actually flight test scramjets. Rather, they are forced to rely on less expensive wind tunnels. To simulate >mach 6 airflow (scramjet operational range), they either use an enourmous piston driven system, or a series of pressure build ups with a simultaneaous release. Regardless of the method, these techniques generally can't provide more than 5 milliseconds of flow time to test the engine. If you compare testing engines in 5 ms bursts to one sustained 10 s flight, the perspective kind of changes your opinion on how long 10 s is.
If you want a good paper on the subject, I suggest this one from the Australian National University.
um no, some very simple math indicates that if you go up 1 mile, the circumference is only about 6 miles longer. You have a point, but it's not nearly as big an effect (especially considering thinner air -> efficiency at high altitudes).
Well, as other posters have pointed out, it's quite simple to achieve ludicrous speeds in space, and the space shuttle regularly goes WAY faster than mach 7. However, for atmospheric flight the current record is held by the NASA/AF X-15 program in the 60's. In 1967 it hit a top speed of mach 6.7 and had two flights to over 100 km altitude (that's high enough to win the X-prize). The program was a great success, but had two failures, one of which totaled on of the planes and killed its pilot. Humans haven't returned to hypersonic (>mach 5) atmospheric flight since the program was cancelled (unless it's classified).
It might not seem that this scramjet test is that impressive given that it is only going 0.3 mach faster, and that it isn't even manned, but it does reflect the direction of the last 40 years of aviation innovation - efficiency. Whereas the X-15 was powered by a rocket, this will have a full airbreathing engine. However, I'll agree that if you look at the fact that Yeager broke mach 1 in 1947, and the X-15 hit mach 6.7 in 1967, it's pretty sad that we have no craft capable of even taking a human faster than mach 5 in 2004.
It's good to all have a laugh, but I actually know two guys who made a small fortune doing this. I'm from B.C. (west coast of Canada) which has a HUGE forestry industry. A good portion of the logs are hauled down to Vancouver in giant log booms towed by tug-boats. Inevitably, things go wrong and booms get lost, logs sink, get ensnared in cables, or whatever. Just a few months ago I met two guys who set themselves up to do log recovery a few years back. They do all SCUBA work, and basically the go down in places where there's known to be lots of old-growth logs that have sunk. They cut the cables and free up the logs and float them to the surface. Since these logs have been down there for ages, they technically count as salvage. That means these guys now own the logs outright and can sell them directly back to the forestry company. At >$10,000 per tree for those huge old-growth trees, they've actually made some significant coin at it.
The only downside to the work is that it's really dangerous. About a year ago they had an employee who was killed when cables got tangled wrong and the logs unfolded unexpectedly when the airbags were inflated. The guy got crushed between two big logs, and despite rushing him to hospital he died. I guess this is just another industry where robots are taking over profitable jobs that are too dangerous to justify humans doing them.
Personally I think his arguments are completely bunk - he just argues that just because something is small doesn't mean it shouldn't be considered a planet. Well, I hate to burst his bubble, but there are tons of small things out there that we don't call planets precisely because they are smaller: Asteroids! The human and dog analogy is completely inappropriate here - it's more like the difference between a boulder and a pebble. At what point does a rock become to small (or even big I suppose) to be considered a boulder? Too big to be considered a pebble? While not many people care about the exact, qualitative distinction between boulders and pebbles, the difference between asteroids and planets has all sorts of ramifications for cosmological classification systems. You have to draw the line somewhere.
My personal vote goes to the system that would make Pluto (and therefore Sedna, Ceres, et al) NOT a planet, but have Pluto grandfathered in solely for historical reasons.
Well, theoretically there may be no such thing as a centrifugal force, but in practice it makes a lot of sense to have a name for the relative force caused by centripetal acceleration. And calling it a tangential force makes almost no sense because there is nothing tangential about the centripetal acceleration - in fact if you are using a polar coordinate system (which it makes sense to do in this case) that tangential force is solely responsible for an angular acceleration and is actually completely perpendicular to the centripetal force. BTW, a centripetal force, or centripetal acceleration is what it is called.
I'm an engineer (mechanical), and while I and all the people I work with realize that there is technically no such thing as a centrifugal force, it's not uncommon to reference it in a discussion because it's simply more practical.
Slashdot Mirror
Actually, an interesting thing I found out the other day - several hundred years ago, in post-medieval europe, one of the causes of death was "planet". This is what happened when a person died mysteriously when the planets were aligned in a particular way. It was interpreted as the planets having struck them down. So what did they really die of?
Forgive what may be an ignorant question - but how does having a moon slow down a planet's rotation? You mention angular momentum, but I have trouble seeing how that applies given that the moon and the planet are not connected (i.e. can't the moon and planet each have separate angular momentums? How does angular momentum of the moon get attached to the planet's angular momentum so that they act as a system?). I'm pretty curious how this works.
I think that ISPs could simply then start looking for seemingly random port probes by machine A on machine B, followed by machine B spewing gobs of data to machine A on a random port. That's the trick, make your protocol too good and it'll stand out because it's too random. If you ever actually talk to anyone who works at ISPs though, they generally just flag those customers with unbelievable upload/download ratios and then have a human look at their logs to see if they're violating the TOS (running a server, hosting warez, whatever).
Three things:
/. without a reference, and that 1 million pounds for an expedition definitely sounds like a number out of thin air. Without looking at their designs, it's really impossible to speculate on the final weight/mass of the vehicle.
First off, your assumption that they will use Proton rockets may be wrong - they may use a reconstructed Russian variant of a Saturn V, and launch everything in one or two trips. There's another post on this article that suggests alternatives to the Proton.
Secondly, I don't trust many numbers thrown around on
Finally, and perhaps most importantly, why go into orbit to assemble your vehicle? Why not launch it pre-assembled on a big-ass rocket (see pt. 1) and go straight for mars or whatever bodies you're using for a gravity assist trajectory? Going into orbit uses a lot of energy, and I really don't see the need for it. A lot of sci-fi involves orbital assemblies, but when you do the math it's not actually that practical...
All that being said however, I agree that I can't see this mission flying. It reeks of overly optimistic budgeting designed to secure enough venture capital to get some executives a fun, well paying job for a few years before the project dies in a sea of red ink.
Yea, I'd pick July 1st - Canada's birthday! :-)
Thanks for correcting me - you learn something new every day. BTW, you've got a new friend...
IIRC, the exocet that struck the HMS Sheffield did detonate, but that was not the main problem. The problem was that the Type 42 Destroyer class used almost solid aluminium superstructures. In extremely high temperatures, aluminium can burn (just like magnesium, but even higher temps). When the ship was struck, it ignited the aluminium which then steadily burned. This is why you no longer see ships produced with all-aluminium superstructures any more.
Yeah, I thought the dance was pretty amazing - I had no idea that we'd come that far in robotics. However, I watched it a few times and if you focus on the feet, you realize that they're mostly just waving their arms, and their feet are making very small steps left, forward, turning, etc. The armwaving is considerably easier to manage in robotics, unless it's standing on one foot (notice that the robots didn't wave their arms much when they did that little demo of standing on one foot (mind you, I know plenty of humans that can't do that).
Still a pretty damn impressive show. The actuation in the arms was especially convincing. I'd like to see it in person actually.
Presumably it could be overwritten to obscure it whereas a watermark could not be removed without destroying the original data.
Actually, there is a method of removing watermarks. What you have to do is get multiple versions of the file - each with a different watermark (i.e. purchase the same song with different accounts multiple times). Then you take the files and average them. For every file you add to this process, the watermark becomes more obscured. Now, it might be impractical right now, but it is not difficult to change.
shit, that sounds even cooler - and it would actually be practical too! It'd be sweet to ride down the street on that and just watch the looks people give you...
yeah, but if we used a fractally patterned tread, the wheels would lock into the road and then you'd have a hard time going anywhere, regardless of the fact that you have an infinite road surface to drive on. :-)
That bike actually sounds pretty cool. Though it is ultimately more practical than this one, it still has a major drawback in that at certain times in a rotation (when there's a flat side down), square wheels will require ENOURMOUS amounts of torque to move forward and at others (when it's sitting on a point) it will require none at at. Devising a powertrain that can provide this kind of harmonically varying load given is another challenge that stands in the way of building a usable bike with square wheels.
Actually, the famous physicist Heisenberg worked was the guy that the Nazis consulted on whether nuclear weapons were feasible. It has never been proven, but there is evidence to suggest that Heisenberg purposely fudged his calculations by introducing errors which are very elementary, and should have been recognized and fixed. This was primarily evident in his critical mass calculations, in which he used a plane of uranium, rather than a sphere, resulting in an enourmous, untransportable amount of uranium required to produce a fission explosion.
As well, the German program was retarded by their failure to realize that graphite was usable as a moderator. They thus invested enourmous energy and finances into heavy-water production, which is actually quite a technically difficult process.
This is also a technique commonly used in fruit farming. If a farmer is worried about a frost damaging his fruit, he can go around and spray water on all the fruit. When temperatures drop, the water freezes and the fruit doesn't. It also helps that ice is a pretty good insulator, so once it's frozen you now have effectively encased each fruit in an insulating shield. This is used regularly throughout the US, and I'd bet it's used around the world too.
He actually might have a future in competitive eating - I don't know anyone, even championship hotdog eaters, that has attempted to eat a 10-minute struggle!
Um, if you read the page you linked to, it says that the four test-launches of the N1 that they did were all miserable failures - maybe this also had something to do with their decision to kill the plans?
do you have a Celestia update file for messenger (either its planned trajectory, or this revised one)? I'd be interested in getting that if you do
Um, no, and no.
Angular momentum refers to the linear momentum of the probe times the radius from the sun at which it is orbiting.
As for the energy, It's actually pretty tricky to lose KE + PE in space - you either have to use engines (with expensive-to-launch fuel) or sophisticated aerobraking techniques and whatnot by making close passes to other planets. In fact, when this probe gets to Mercury, if i'm not mistaken, it will still have nearly the same energy (in terms of KE and PE).
In the scramjet reasearch buisiness, 10 seconds is an eternity. Most institutions who are researching this technology are universities and the like who don't have access to B-52s, rocket boosters, and the other equipment needed to actually flight test scramjets. Rather, they are forced to rely on less expensive wind tunnels. To simulate >mach 6 airflow (scramjet operational range), they either use an enourmous piston driven system, or a series of pressure build ups with a simultaneaous release. Regardless of the method, these techniques generally can't provide more than 5 milliseconds of flow time to test the engine. If you compare testing engines in 5 ms bursts to one sustained 10 s flight, the perspective kind of changes your opinion on how long 10 s is.
If you want a good paper on the subject, I suggest this one from the Australian National University.
um no, some very simple math indicates that if you go up 1 mile, the circumference is only about 6 miles longer. You have a point, but it's not nearly as big an effect (especially considering thinner air -> efficiency at high altitudes).
Well, as other posters have pointed out, it's quite simple to achieve ludicrous speeds in space, and the space shuttle regularly goes WAY faster than mach 7. However, for atmospheric flight the current record is held by the NASA/AF X-15 program in the 60's. In 1967 it hit a top speed of mach 6.7 and had two flights to over 100 km altitude (that's high enough to win the X-prize). The program was a great success, but had two failures, one of which totaled on of the planes and killed its pilot. Humans haven't returned to hypersonic (>mach 5) atmospheric flight since the program was cancelled (unless it's classified).
It might not seem that this scramjet test is that impressive given that it is only going 0.3 mach faster, and that it isn't even manned, but it does reflect the direction of the last 40 years of aviation innovation - efficiency. Whereas the X-15 was powered by a rocket, this will have a full airbreathing engine. However, I'll agree that if you look at the fact that Yeager broke mach 1 in 1947, and the X-15 hit mach 6.7 in 1967, it's pretty sad that we have no craft capable of even taking a human faster than mach 5 in 2004.
It's good to all have a laugh, but I actually know two guys who made a small fortune doing this. I'm from B.C. (west coast of Canada) which has a HUGE forestry industry. A good portion of the logs are hauled down to Vancouver in giant log booms towed by tug-boats. Inevitably, things go wrong and booms get lost, logs sink, get ensnared in cables, or whatever. Just a few months ago I met two guys who set themselves up to do log recovery a few years back. They do all SCUBA work, and basically the go down in places where there's known to be lots of old-growth logs that have sunk. They cut the cables and free up the logs and float them to the surface. Since these logs have been down there for ages, they technically count as salvage. That means these guys now own the logs outright and can sell them directly back to the forestry company. At >$10,000 per tree for those huge old-growth trees, they've actually made some significant coin at it.
The only downside to the work is that it's really dangerous. About a year ago they had an employee who was killed when cables got tangled wrong and the logs unfolded unexpectedly when the airbags were inflated. The guy got crushed between two big logs, and despite rushing him to hospital he died. I guess this is just another industry where robots are taking over profitable jobs that are too dangerous to justify humans doing them.
you should try whitehouse.com - that's even funnier... :-)
Personally I think his arguments are completely bunk - he just argues that just because something is small doesn't mean it shouldn't be considered a planet. Well, I hate to burst his bubble, but there are tons of small things out there that we don't call planets precisely because they are smaller: Asteroids! The human and dog analogy is completely inappropriate here - it's more like the difference between a boulder and a pebble. At what point does a rock become to small (or even big I suppose) to be considered a boulder? Too big to be considered a pebble? While not many people care about the exact, qualitative distinction between boulders and pebbles, the difference between asteroids and planets has all sorts of ramifications for cosmological classification systems. You have to draw the line somewhere.
My personal vote goes to the system that would make Pluto (and therefore Sedna, Ceres, et al) NOT a planet, but have Pluto grandfathered in solely for historical reasons.
Well, theoretically there may be no such thing as a centrifugal force, but in practice it makes a lot of sense to have a name for the relative force caused by centripetal acceleration. And calling it a tangential force makes almost no sense because there is nothing tangential about the centripetal acceleration - in fact if you are using a polar coordinate system (which it makes sense to do in this case) that tangential force is solely responsible for an angular acceleration and is actually completely perpendicular to the centripetal force. BTW, a centripetal force, or centripetal acceleration is what it is called.
I'm an engineer (mechanical), and while I and all the people I work with realize that there is technically no such thing as a centrifugal force, it's not uncommon to reference it in a discussion because it's simply more practical.