In principle, any mass, if packed densely enough, could become a black hole. For each mass - from a cluster of atoms to an entire galaxy - there is a calculable quantity called the Schwarzschild radius. If you could somehow pack the mass so that it fit inside a volume smaller than that mass's Schwarzschild radius, the force of gravity would invariably overcome all other forces and cause the mass to become a singularity. The Schwarzschild radius also defines the "edge" of the black hole - if anything, including light, gets closer than one Schwarzschild radius from the central mass, it will not be able to escape. In other words, at the Schwarzschild radius, the escape velocity is the speed of light.
It is easy to see how the core of a really big star could collapse on itself in a supernova - there's just so much mass, coupled with the force of the explosion. However, our own sun could become a black hole - if some as-yet unknown physical process could squeeze its entire mass into a 6-km diameter sphere. The Schwarzschild radius of one solar mass is about 3 km.
It is important to note that, were this to happen tomorrow, the Earth and the other planets would continue to orbit the black hole sun exactly as they have done for billions of years. The gravity of the sun hasn't changed, because its mass hasn't changed. If you were, however, unfortunate enough to come within 3 km of the center of the black hole sun, that's the last the universe would ever see of you. (As a practical matter, you'd be doomed long before then, simply because no rocket would be powerful enough to bring you away once you got closer than a few thousand kilometers. To escape the black hole sun once you were, say, 3.1 km away, you would need to somehow achieve a speed near to the speed of light, which we simply can't do.)
It is also important to note that you would not be sucked into a black hole if you came within 3 km of the center of the sun as it exists today, shining hot and bright. This is because 99.999% of the mass of the sun lies outside of that 3 km radius and so "doesn't count" in terms of the force of gravity. Aside from instantly transforming into plasma from the heat, you would actually feel far less gravity than you would on the Moon. (For reasons why, see here.) Remember: a black hole would exist only if you could compress the whole mass of the sun into that 3-km radius spherical volume.
This can be applied to just about any mass. The Schwarzschild radius of the Earth is about 9 mm - smaller than a grape. This gives you a sense of how densely you'd have to pack things if you wanted to make an Earth-mass black hole. For a pair of protons smashed together at high energies - as in the LHC - I think you need to bring in other areas of physics than just general relativity. Suffice to say the Schwarzschild radius would be much, much, much smaller than the size of a proton, which in turn is much, much, much smaller than the size of an atom, which is much smaller than the distance between atoms in most solids. So in order for a micro-black-hole to accumulate mass, it would need to pass very close, on the order of its Schwarzschild radius, to the nucleus of another atom. At the length scales we are talking about, that's about as likely as me randomly shooting off a bb gun and hitting a passing bird a kilometer away.
So rest easy, the world isn't about to end.
I apologize for the long answer, but I hope it has answered your question.
It is likely that most of the parts of the world you think are overpopulated (with the notable exceptions of China and India) have lower population densities than the parts you think are not overpopulated.
Ordinarily I'd ask that you provide statistics to back up such a claim, but I'll skip that to point out just this:
The only way that very densely populated places like Western Europe, Japan, parts of the USA, and Korea are able to sustain that density is by importing lots of their necessities from places that are less dense, then exporting the waste back to those less dense areas. On the whole, humanity is getting by (not yet having mass die-offs) supporting a population of 6 billion, but when more of the less dense places that provide food and raw materials become as crowded as Japan, how are we going to feed and clothe ourselves, let alone keep the lights on?
Nothing against you or your fiance, but it seems that she has more than made up for you, since while in this generation there are just the two of you, your childrens' generation has four. Congratulations, you've doubled the population in a generation.
The major problems keeping these things out of power transmission have been temperature and the problem where superconductivity halts if you try to put more than a small amount of current per unit of area through it
In terms of infrastructure, this is actually a desirable effect: the cable is self-limiting. One of the reasons that blackouts become such a problem is that a problem in one location causes substantially more power to flow through alternate routes - routes that weren't designed to handle the load. Hot cables aren't so much the problem as fried transformer substations. Cable can be restrung relatively quickly and cheaply; replacing large transformers is expensive and time-consuming. A current-limited superconducting transmission trunk should be able to "shut off" flow before damage to downstream systems occur. This is something that is being demonstrated in a few real-world projects (one on Long Island I think). One can also buy a standalone superconducting fault current limiter - think of it as a utility-scale fuse.
Which is precisely why we need an international molasses non-proliferation treaty. Then, when rogue nations refuse to sign it, we'll have that much more justification for bombing their storage tanks!
My point with the Hiroshima bomb is that the nuclear fuels used have enormous sunk energy costs in mining, refining, enriching, and shaping them into the final weapon. Thirteen kilotons of TNT is the energy equivalent of 15 gigawatt-hours, or a couple thousand gallons of gasoline. How much fuel did the Enola Gay use to deliver the bomb, how much for the Indianapolis to transport it across the Pacific, how much electrical energy to enrich the uranium at Oak Ridge? Overall, orders of magnitude more energy went into the production of that weapon than was actually released by it. But all that energy couldn't be delivered in a compact blow like you get with a nuclear weapon, so, bombs away!
But getting back to the Star Trek - yes, you need to produce antimatter, and doing so takes a lot more energy than you can recapture from it. But so what? The same could be said for the cryogenic fuels used in rockets and spacecraft. The reason why they get used is because their energy content is much more available and in a more useful form than all the energy that went into producing them.
By extension, no one serious about the subject considers hydrogen to be an energy source. It can't be mined from the atmosphere or ocean; it must be chemically extracted using yet more energy. It is a fuel, a material means to transport energy in a way that makes (some) sense, even if energy is lost along the way. The same would be true of the anti-matter in Star Trek. It's not the ultimate source of energy, just a carrier of it.
As for safety, I will definitely conceed that it's difficult, probably intractable. Figuring out a containment method that can fail safely and gracefully is the trickiest bit. But, who knows, that might be a well-established technology by the (real) 24th century.
As it is in Star Trek, it is a very useful way to produce energy - if you need a tremendous amount of energy in a relatively small space released in a big hurry. It doesn't need to be a net-energy gain in order for it to be useful. The Hiroshima blast was about 13 kilotons of TNT worth of energy. Just how much energy do you think went into making the bomb?
My last place of work was rather straight-laced. All the professional staff were expected to wear business attire, kinda like this; even us work-a-day engineers and IT folks.
The study controls for teachers' reports of aggression and impulsivity at age 10, the child's gender, and parenting style.
That still does not imply causation, merely much more tight correlation. It could be that violent people simply like candy more, not that the candy led an otherwise good child to grow into a violent offender. It could be that there is yet another cause, beyond what the researchers controlled for, that is the cause of both the sweet tooth and violent behavior.
A way to make the causation argument more substantive would be to come up with a way to test their causation hypothesis:
The researchers theorize the correlation comes from the way candy is given rather than the candy itself. Candy frequently given as a short-term reward can encourage impulsive behavior, which can more likely lead to violence.
I'm guessing that this might be what's next for them.
Hovever - What Exaclty is a phone company supposed to tell the FBI or CIA when they show up with a request from the AG/President?
Considering that complying with such a request without judicial approval is against the law? Yes, indeed, what should they have done?
There were laws in place, the FISA court, an entire fucking apparatus for dealing with such requests in a way that balanced national security and civil rights. The telco lawyers and regulatory affairs offices knew of the apparatus, had interacted with it before, and yet set the whole thing aside at the say-so of an overbearing administration. Fears about "lack of cooperation" is a bullshit excuse.
"I did as I was told" has been the flimsy excuse of who-knows-how-many culpable collaborators in both war and peace. We still managed to hold them accountable.
I was pissed as all get out that the telcos got immunity for cooperating with an illegal government action. They should have had their asses nailed to the wall, as a reminder that businesses should not accept the government at its word about national security.
At this point, however, I wonder if revoking the immunity is a good way to go. It's not quite the same as double jeopardy, since the companies were not acquitted by a jury, but it's close. In order for companies to function, they need some predictability. Congress' granting retroactive immunity to the telcos set a bad precedent. But having done so, revoking it also sets a bad precedent.
On the other hand, is it ever late too late to seek justice?
Thankfully, as the article states, the military isn't planning on making this aircraft to open a speedy and luxurious cruise line over Afghanistan. The airships will be used for aerial surveillance, where staying in one place for long periods of time is the main goal. They are designed to remain aloft for a few weeks at a time, something that ordinary aircraft can't do.
It's done over a cable - something the summary and most articles I've seen on it has failed to make apparent.
I did wonder about its usefulness myself, though. Why would I need to connect my iPhone to five different things at once? I rareky even need to connect my laptop to more than one or two things at a time.
Then I gave it some more thought and it occurred to me: at some point in the not-too-distant future smartphones will have the capabilities of today's laptops in terms of computing power and storage. You're unlikely to use that much power on the go, and you're hampered by the small screen and keyboard. But, for at least a segment of the population, you'll be able to dock your supersmartphone much like you can dock a laptop today. The dock will connect to a larger monitor, perhaps a keyboard and mouse (though those may be wireless direct to the phone), network, optical drive, offline storage, printer, and other peripherals. Your smartphone would be the computing guts of a much broader and capable system.
But the docking connectors on dock-able laptops are enormous compared to the size of a smartphone. Having a single, small, optically-based connector that can connect your phone to all those other devices will be key to this paradigm.
That is, of course, unless wireless technologies completely supplant wired connections for peripherals.
computer programmes which act as 'agents' to monitor and process information.... Its main objectives include the 'automatic detection of threats and abnormal behaviour or violence
Miller said. "Snow Leopard's more secure than Leopard, but it's not as secure as Vista or Windows 7," he said. "When Apple has both [in place], that's when I'll stop complaining about Apple's security."
Call me a cynic, but I somehow think he, and everyone else that looks at OS security, will still find things to complain about. The tech blog and journalism industry depends on it!
Slashdot Mirror
That just makes me cry.
In principle, any mass, if packed densely enough, could become a black hole. For each mass - from a cluster of atoms to an entire galaxy - there is a calculable quantity called the Schwarzschild radius. If you could somehow pack the mass so that it fit inside a volume smaller than that mass's Schwarzschild radius, the force of gravity would invariably overcome all other forces and cause the mass to become a singularity. The Schwarzschild radius also defines the "edge" of the black hole - if anything, including light, gets closer than one Schwarzschild radius from the central mass, it will not be able to escape. In other words, at the Schwarzschild radius, the escape velocity is the speed of light.
It is easy to see how the core of a really big star could collapse on itself in a supernova - there's just so much mass, coupled with the force of the explosion. However, our own sun could become a black hole - if some as-yet unknown physical process could squeeze its entire mass into a 6-km diameter sphere. The Schwarzschild radius of one solar mass is about 3 km.
It is important to note that, were this to happen tomorrow, the Earth and the other planets would continue to orbit the black hole sun exactly as they have done for billions of years. The gravity of the sun hasn't changed, because its mass hasn't changed. If you were, however, unfortunate enough to come within 3 km of the center of the black hole sun, that's the last the universe would ever see of you. (As a practical matter, you'd be doomed long before then, simply because no rocket would be powerful enough to bring you away once you got closer than a few thousand kilometers. To escape the black hole sun once you were, say, 3.1 km away, you would need to somehow achieve a speed near to the speed of light, which we simply can't do.)
It is also important to note that you would not be sucked into a black hole if you came within 3 km of the center of the sun as it exists today, shining hot and bright. This is because 99.999% of the mass of the sun lies outside of that 3 km radius and so "doesn't count" in terms of the force of gravity. Aside from instantly transforming into plasma from the heat, you would actually feel far less gravity than you would on the Moon. (For reasons why, see here.) Remember: a black hole would exist only if you could compress the whole mass of the sun into that 3-km radius spherical volume. This can be applied to just about any mass. The Schwarzschild radius of the Earth is about 9 mm - smaller than a grape. This gives you a sense of how densely you'd have to pack things if you wanted to make an Earth-mass black hole. For a pair of protons smashed together at high energies - as in the LHC - I think you need to bring in other areas of physics than just general relativity. Suffice to say the Schwarzschild radius would be much, much, much smaller than the size of a proton, which in turn is much, much, much smaller than the size of an atom, which is much smaller than the distance between atoms in most solids. So in order for a micro-black-hole to accumulate mass, it would need to pass very close, on the order of its Schwarzschild radius, to the nucleus of another atom. At the length scales we are talking about, that's about as likely as me randomly shooting off a bb gun and hitting a passing bird a kilometer away.
So rest easy, the world isn't about to end.
I apologize for the long answer, but I hope it has answered your question.
Ordinarily I'd ask that you provide statistics to back up such a claim, but I'll skip that to point out just this:
The only way that very densely populated places like Western Europe, Japan, parts of the USA, and Korea are able to sustain that density is by importing lots of their necessities from places that are less dense, then exporting the waste back to those less dense areas. On the whole, humanity is getting by (not yet having mass die-offs) supporting a population of 6 billion, but when more of the less dense places that provide food and raw materials become as crowded as Japan, how are we going to feed and clothe ourselves, let alone keep the lights on?
Nothing against you or your fiance, but it seems that she has more than made up for you, since while in this generation there are just the two of you, your childrens' generation has four. Congratulations, you've doubled the population in a generation.
This explains how chemistry textbooks keep coming out with new editions every freakin' year so they can charge you an arm and a leg.
I'm trying to figure out what you are referring to.
Ridgeway, WI?
this guy's house in Belleville, IL?
Memphis, TN?
New Orleans, LA?
The Galapagos Islands?
In terms of infrastructure, this is actually a desirable effect: the cable is self-limiting. One of the reasons that blackouts become such a problem is that a problem in one location causes substantially more power to flow through alternate routes - routes that weren't designed to handle the load. Hot cables aren't so much the problem as fried transformer substations. Cable can be restrung relatively quickly and cheaply; replacing large transformers is expensive and time-consuming. A current-limited superconducting transmission trunk should be able to "shut off" flow before damage to downstream systems occur. This is something that is being demonstrated in a few real-world projects (one on Long Island I think). One can also buy a standalone superconducting fault current limiter - think of it as a utility-scale fuse.
Which is precisely why we need an international molasses non-proliferation treaty. Then, when rogue nations refuse to sign it, we'll have that much more justification for bombing their storage tanks!
The Soviets powered some remote sensing stations and lighthouses in Siberia with nuclear batteries.
To modify a quip often rolled out in gun control debates: If we outlaw candy, then only violence-prone 10-year olds will have candy.
My point with the Hiroshima bomb is that the nuclear fuels used have enormous sunk energy costs in mining, refining, enriching, and shaping them into the final weapon. Thirteen kilotons of TNT is the energy equivalent of 15 gigawatt-hours, or a couple thousand gallons of gasoline. How much fuel did the Enola Gay use to deliver the bomb, how much for the Indianapolis to transport it across the Pacific, how much electrical energy to enrich the uranium at Oak Ridge? Overall, orders of magnitude more energy went into the production of that weapon than was actually released by it. But all that energy couldn't be delivered in a compact blow like you get with a nuclear weapon, so, bombs away!
But getting back to the Star Trek - yes, you need to produce antimatter, and doing so takes a lot more energy than you can recapture from it. But so what? The same could be said for the cryogenic fuels used in rockets and spacecraft. The reason why they get used is because their energy content is much more available and in a more useful form than all the energy that went into producing them.
By extension, no one serious about the subject considers hydrogen to be an energy source. It can't be mined from the atmosphere or ocean; it must be chemically extracted using yet more energy. It is a fuel, a material means to transport energy in a way that makes (some) sense, even if energy is lost along the way. The same would be true of the anti-matter in Star Trek. It's not the ultimate source of energy, just a carrier of it.
As for safety, I will definitely conceed that it's difficult, probably intractable. Figuring out a containment method that can fail safely and gracefully is the trickiest bit. But, who knows, that might be a well-established technology by the (real) 24th century.
As it is in Star Trek, it is a very useful way to produce energy - if you need a tremendous amount of energy in a relatively small space released in a big hurry. It doesn't need to be a net-energy gain in order for it to be useful. The Hiroshima blast was about 13 kilotons of TNT worth of energy. Just how much energy do you think went into making the bomb?
Not according to Dan Brown.
My last place of work was rather straight-laced. All the professional staff were expected to wear business attire, kinda like this; even us work-a-day engineers and IT folks.
xkcd said it better.
That still does not imply causation, merely much more tight correlation. It could be that violent people simply like candy more, not that the candy led an otherwise good child to grow into a violent offender. It could be that there is yet another cause, beyond what the researchers controlled for, that is the cause of both the sweet tooth and violent behavior.
A way to make the causation argument more substantive would be to come up with a way to test their causation hypothesis:
I'm guessing that this might be what's next for them.
My question is: after your 3rd day awake in Vegas with a .28 and a swollen left eye, why on earth are you checking up on Slashdot?
Isn't this just the same story from two days ago?
Considering that complying with such a request without judicial approval is against the law? Yes, indeed, what should they have done?
There were laws in place, the FISA court, an entire fucking apparatus for dealing with such requests in a way that balanced national security and civil rights. The telco lawyers and regulatory affairs offices knew of the apparatus, had interacted with it before, and yet set the whole thing aside at the say-so of an overbearing administration. Fears about "lack of cooperation" is a bullshit excuse.
"I did as I was told" has been the flimsy excuse of who-knows-how-many culpable collaborators in both war and peace. We still managed to hold them accountable.
Ah, thank you! I have now received my recommended daily allowance of sarcasm.
And yet I feel so sad and empty inside...
I was pissed as all get out that the telcos got immunity for cooperating with an illegal government action. They should have had their asses nailed to the wall, as a reminder that businesses should not accept the government at its word about national security.
At this point, however, I wonder if revoking the immunity is a good way to go. It's not quite the same as double jeopardy, since the companies were not acquitted by a jury, but it's close. In order for companies to function, they need some predictability. Congress' granting retroactive immunity to the telcos set a bad precedent. But having done so, revoking it also sets a bad precedent.
On the other hand, is it ever late too late to seek justice?
Thankfully, as the article states, the military isn't planning on making this aircraft to open a speedy and luxurious cruise line over Afghanistan. The airships will be used for aerial surveillance, where staying in one place for long periods of time is the main goal. They are designed to remain aloft for a few weeks at a time, something that ordinary aircraft can't do.
It's done over a cable - something the summary and most articles I've seen on it has failed to make apparent.
I did wonder about its usefulness myself, though. Why would I need to connect my iPhone to five different things at once? I rareky even need to connect my laptop to more than one or two things at a time.
Then I gave it some more thought and it occurred to me: at some point in the not-too-distant future smartphones will have the capabilities of today's laptops in terms of computing power and storage. You're unlikely to use that much power on the go, and you're hampered by the small screen and keyboard. But, for at least a segment of the population, you'll be able to dock your supersmartphone much like you can dock a laptop today. The dock will connect to a larger monitor, perhaps a keyboard and mouse (though those may be wireless direct to the phone), network, optical drive, offline storage, printer, and other peripherals. Your smartphone would be the computing guts of a much broader and capable system.
But the docking connectors on dock-able laptops are enormous compared to the size of a smartphone. Having a single, small, optically-based connector that can connect your phone to all those other devices will be key to this paradigm.
That is, of course, unless wireless technologies completely supplant wired connections for peripherals.
That's already been done before.
Call me a cynic, but I somehow think he, and everyone else that looks at OS security, will still find things to complain about. The tech blog and journalism industry depends on it!