I have mixed feelings about this. It's great to see a more inherently-safe reactor design being popularized. But on the other hand, it reminds me of just how much ground we (the U.S.) have lost compared to other nations.
I worked at General Atomic in the 1980s. At that time, they had a complete high temperature gas-cooled pebble reactor design, but were having regulatory troubles building and deploying one in the U.S.
Now the Chinese nuclear physicists will eat their lunch. Sorry, guys. Here's hoping that you'll finally get to build 'em here.
"Mathematicians use the first definition almost exclusively..."
Well, certainly. That just means that mathematicians know precisely the thing about which they are talking (the "complex numbers" has a very precise meaning, to someone who has followed the formal definition of the set). Since the Riemann hypothesis deals with functions defined on the set of complex numbers (and limits of functions), it is very precisely posed.
I will not go through the exercise of proving so here, but there really isn't any way to come up with more than one answer, without speaking of something other than the usual complex numbers.
You "...could say that numbers are actual entities, and that there is an actual set of complex numbers that exists in some sense... [that] isn't precisely defined." -- but such a set would not be the "complex numbers" that are being described by mathematicians. It would be something else entirely.
Hmmm... Thanks for the "...of course you are right...", but, er, you just described the definition of decidability. If it's "impossible to write a [n algorithm] which takes as input a description of a program P and a description of an input x and decides whether P halts on x", then the question of whether P halts on x is not decidable.
``Magnetic motors'' - bah. They don't conserve energy, so most rational people don't believe in them. I've analyzed a few designs myself, for fun when I was a gradual student. There's always some little mistake the inventor made, where the power gets lost. Then, when you point it out, they get angry at you for spoiling their perfect idea.
No, er, actually, decidability is all about being able to determine, in advance, whether program 'A' or program 'B' is right for a particular set of inputs.
The whole point of the halting problem is that there are computational sequences of all lengths (including aleph-null) that are irreducible. You can't know the result of such an irreducible sequence unless you've run through a certain minimum number of logical steps. In some sense, you can't know the answer to an irreducible computing problem unless you've brute-forced the answer already.
Saying "of course it's decidable -- either program A or program B is the correct answer" is not legitimate. The whole point of the halting problem is that it's impossibly hard to decide which (of A or B) is the correct answer in all cases. There are a few cases for which you'd have to wait literally forever.
Of course, there's a very large class of computations that are in fact decidable. In a lot of cases, it's enough to say "this halts in less time than X" or "this doesn't halt in less time than X", for a finite value of X.
In the 1960s, several automotive companies looked into turbine power -- in fact, a semi truck powered with a turbine power plant traveled coast-to-coast to demonstrate the technology. The problem is that turbines are only efficient in a particular, even narrower range of power outputs than infernal combustion engines.
That made turbine engines impractical for the last four decades -- but a turbine might be just the ticket for a series hybrid car. The batteries then become a power conditioner / load leveler that isolates the turbine from the wheels better than any transmission could...
In fact, for a while I considered doing exactly what the article suggests -- making my existing car (a VW microbus) into a series hybrid. My idea was to pull the engine (but not transaxle) and adapt a series-wound DC motor to the transaxle. Then put a small deck on top of the motor (about where the normal shrouding goes) and stick either a commercial generator or a small aviation APU on top of it (where the carburetors and other ancillary crap for the VW engine would normally live). There's enough room on either side of the engine comparement to hold about a dozen car batteries, with a custom rack mount (I was planning on UniStrut, the Erector set for grown-ups). Supporting all that weight was an issue -- but you can buy heavy-duty torsion bars that would support it all.
Then I gave my van to a starving artist and bought a Prius. Haven't looked back.
Fuel cell technology is likely to succeed, in the sense the fuel cells become a not-too-expensive way to power, say, a car. But the other half of the infrastructure -- producing renewable fuels from non-petroleum energy sources -- still has a long, long way to go.
The problem I see stems from the dwindling world supplies of petroleum. There just isn't enough oil to burn at cheap prices, to power all those skycars. On the other hand, there's (comparatively) a lot of uranium around.
Won't take over if they're powered by petroleum
on
A Flying Leap for Cars?
·
· Score: 2, Insightful
The biggest problem (societally) with flying cars is not the individual cost -- it's that they're so energy-intensive. SUV's may have dismal efficiencies, but they look like jellybean riceburners compared to personal helicopters. The "springtail" mentioned in the article gets less than 20 MPG under ideal conditions -- carrying a single person and not counting hover time.
Over the next 50 years, unless renewable, portable fuel (e.g. fuel cells together with solar or nuclear electrolysis plants) become insanely cheap, the name of the transportation game will be "efficiency". $40/barrel oil may seem expensive now, but in another few decades it'll seem insanely cheap.
AJWM made a comment about the amount of uranium in coal, and added a little spice about the energy content of that uranium. I went back and did a back-of-the-envelope and found that, hey wow, it works.
In practice, it would be quite difficult to extract those 75 mg of uranium from the tonne of coal, making coal about a suitable as cola for uranium ore -- but AJWM has a point that fly ash (which presumably contains precipitatable uranium oxide) might be a good ore.
The problem that caused the steam explosion was Xe-135 buildup. Xe-135 is a fission daughter product. It is a secondary product (produced by decay of fission products) and itself decays with a few-hour half-life. Xe-135 is a "neutron poison" and when present in the reactor it has the same effect as a control rod, only Xe-135 is much more effective per atom than (say) Cadmium or Boron, the two main materials used for control rods.
Xe-135 is destroyed when it absorbs a neutron. So in an operating reactor is it "burned" rapidly as it is produced. But when you shut off the reaction, Xe-135 levels rise over the next eight hours to a peak level and then decay. This makes it very difficult to start a power reactor eight hours after you shut it down: the Xe-135 acts like an additional control rod, damping the reaction. You find that you have to pull the control rods much farther out to get the reaction started.
There's a problem with that: as soon as you get the reaction going in the core, the Xe-135 will rapidly "burn" off, restoring the usual control laws. That is dynamically unstable, as more neutrons -> less Xe-135 -> more reactive core -> even more neutrons!
The operators should have known what was happening when the found they had to pull the rods much farther than expected in order to bring the reactor stable "zero"-power operation ("zero-power" operation means that a chain reaction is being sustained but is not producing a significant amount of power. It is an important first step in operating the reactor: you start the reaction going, demonstrate positive control, calibrate your control settings, and then proceed to the power level you want. In the reactor where I worked, 5 watts of power, out of a rated maximum of 250 kilowatts, was considered "zero power".).
That unstable positive coefficient (as the Xe-135 burned off) made the reactor spike rapidly in power to a high thermal level -- where the reactor's positive void coefficient [what the Muerte23 described in the parent article] took over. That is a poor element of reactor design -- the Chernobyl reactors were "over-moderated". Fission neutrons come out fast, but uranium absorbs neutrons best when they're moving slowly. So you put the reactive material in a medium (water or graphite or Zirconium hydride or whatever) that will absorb energy from the neutrons without absorbing the neutrons themselves -- they bounce around, losing energy, until they can be absorbed by the core. Too little moderation, and the core won't start up. Too much moderation, and the neutrons will get absorbed and the core won't start up. The Chernobyl reactors were over-moderated, so that small voids in the graphite/water matrix in the core would increase the reactivity of the core. That's just stupid -- properly designed reactors are under-moderated, so that if the water boils the reaction tends to shut itself down.
Anyhow, all that would be moot except that the operators had disabled the main reactor shutdown mechanisms -- they couldn't SCRAM (or rapidly re-insert the rods into the core), but were forced to rely on the much slower drive mechanisms -- which couldn't contain the reaction. A rapid-drop SCRAM system existed (and would have saved the facility) but had been disabled for testing.
The problem (as I see it) with nuclear power is that people are such fuckin' idiots. Reactors are completely safe around people with what is called "common sense" but unfortunately, common sense isn't. Eventually, pointy haired bosses and Joe Sixpack rule the day.
(BTW, I hold a no-longer-current nuclear reactor operator's license).
This last comment was interesting enough that I looked it up.
According to the USGS,
most coal has a concentration of under 2 ppm (mass/mass, I think) of
uranium. However, a significant amount of coal in the U.S. has
concentrations of 10ppm and above. Now, U-235, the useful isotope,
has a relative abundance of 0.75%, so if you select the proper mine
you can get about (7.5e-3)(1e-5)(1e9 mg/tonne) = 75 milligrams of U-235
per tonne of coal (note "tonne"=1000kg=2200 lb, not "ton"=2000 lb).
Fissioning U-235 releases about 200 MeV/fission, or about
(2e8 eV/fission)(1.6e-19 J/eV)(6.02e23 fissions/235 g)(0.075 g) = 6e9
Joules per tonne of the more enriched coal. That's about 1.6 megawatt-hours
of heat, that can be derived from fissioning the U-235 in a tonne of coal.
Bituminous coal has an energy density of combustion of about
25e9 Joules per tonne, or about 7 megawatt-hours of heat from burning
a tonne of coal.
At first glance, the combustion seems to win, especially when you
consider that you can only get about 10% of the energy out of the
uranium without reprocessing. But if you use the U-238 too (to make
plutonium, which will then also fission in a conventional reactor),
you get about 100x as much energy as from fissioning just the U-235.
Of course, that takes reprocessing the fuel at least once, which is
energy intensive, and there will of course be losses in the system.
So maybe you only win by 30x. The fission
should yield about 50 megawatt-hours of heat in a proper breeder-reactor
setup. That's more than ten times the heat of combustion. Even
"crappy" coal with only 1.5ppm of uranium in it could match the energy of
combustion.
That is to say, how could a hypothetical masturbating guy in a car possibly do any harm to me in my apartment (other than by sucking a bit of bandwidth)? So long as I don't have to see whatever twisted headphone-fetish images he's downloading, why should I, the hypothetical wifi-owner, care?
Hmm... there's an interesting trade-off there. Illuminating your dials with red is a good way to preserve night vision for driving -- but illuminating them with blue is a good way to keep you from having to re-focus too much. Because of dispersion in the eye's lens and cornea, nearly everyone is quite nearsighted in blue. So you can see blue-illuminated gauges in the near field, and then flick back to normally-illuminated streetscape, much quicker than you can look down at (and focus on) a set of red gauges. That probably doesn't matter so much for young drivers, who still have flexible lenses -- but aging drivers whose eyes take longer to focus might actually prefer dim blue illumination to brighter red illumination, despite the blue's effects on night vision.
The article states that this doesn't effect free software at all.
Assuming that you mean "...this doesn't change anything related to free software at all", rather than "...this doesn't create any free software at all", you wanted to use "affect" here instead of "effect".
Remember: If Bob effects chocolate cake, he is making serviceable chocolate cake. If Bob affects chocolate cake, he is causing change in the cake.
(Time to check Strunk and White...)
Most folks don't realize, but there really are four primary colors. Most geeky types are familiar with the red, green, and blue cone cells in our eyes -- but the rod cells that are used for night vision have their own separate response spectrum, weighted heavily toward the blue/violet end of the spectrum.
That means you have four separate "detector systems" in your eye, each of which is sensitive to a different slice of the optical spectrum. In particular, you can distinguish shades of violet and magenta that differ only in the blue-cone/rod response levels.
Ever think about why blue light is used universally to signify "darkness" or "moonlight" on stage? It's because, in low light levels, your cones shut down and your rods -- which in bright light connote blueness -- are the only part of your retina that works well.
It's also the reason why night-vision flashlights are red, and why blue LEDs appear so bright when used as flashlights. The red light doesn't stimulate your rods, preserving their sensitivity; and the blue light gives you extra rod stimulation per unit power, making blue LEDS very efficient as nighttime illumination.
This is a pain, and it has certainly hit us in the PDL world. We're only now starting to get appropriate automated packages built.
On the other hand, if all you need is perl modules (no external libraries) then you can use the CPAN module itself to reach out to CPAN, get the perl code, and test it right there on your system. nearly all the time, it just plain works. That is amazing (to me, anyway).
I want to know that when I buy a "book" for my eBook, I can:
read it now
read it later
lend it to my friends
give it to my children to read
run textual analysis on it
write in the margins
read it on any device that I own.
I don't trust a DRM program to allow me to do those things, especially if my DRM e-book hardware becomes obsolete or breaks. And I don't want to risk going to jail for cracking my own damned copy of the book.
(DMCA).
One might argue that DVDs don't have those things, and were adopted anyway. But DVDs have several things going for them that ebooks do not:
they are physical artifacts and hence give the impression of permanence: once I buy a DVD, well, I own it.
they are better than the preceding technology (VHS) not only because they are more compact, but because they offer a significantly better experience (nice video).
there is pretty much one universal standard.
the cost of the reader is not much larger than the cost of the media. I can get a new DVD player for the cost of about 4-5 DVDs. An e-book reader might cost the equivalent of 30 new paperback books, or 200 used paperback books.
Until e-books are available with either no DRM at all or minimal DRM, I probably won't be buying into them. It's just too annoying to not have control of my own data.
My wife has recently been purchasing some equipment over Ebay. Many of the sellers use PayPal. An interaction between the multiple auctions, PayPal, and the per-charge limit on her credit card meant that she got flagged as a possible fraudster. As a result, not only have several of her auctions not closed -- people who were already paid have lost their money. That is, people who sold us stuff, received the money from PayPal, and sent the stuff had their money pulled back out of their accounts. The money has not been credited back to our credit cards -- it is just... gone. From the point of view of the sellers, we might as well be fraudsters: they have neither their stuff nor their money.
Would you keep using a bank where stories like this kept cropping up? I thought not.
PayPal is useful for amounts up to what you would willingly lose in a poker game -- but for any more serious amount of money, they suck.
Blue lights being out of focus (especially at night) is normal. It is due to dispersion in your eye, and it is a normal phenomenon. The materials that make up your cornea and lens have a higher index of refraction for blue light than for red and green, so you are more nearsighted in blue light than in anything else. The difference is of order 1-2 diopter between red and deep blue/violet. So if your vision is perfect for distant green lights, you can expect to focus slightly closer for red lights (but probably won't notice) and you can expect not to be able to focus for blue lights. The effect is stronger at night, because your pupil is open and the depth-of-field of your focus is much less.
You probably didn't notice that effect when your correction was -5.5, but now that it's 0, it's obvious.
I hacked one together -- it sorts based on the original To: field in the header (which is preserved by sendmail if your provider is using simple virtual hosting). Route any unknown address to your shitpile. Maintain a list of known addresses that you have handed out.
My catchall gets over 2,000 spams a day, mostly from cretins on fishing expeditions for valid accounts.
And yet one may certainly calculate the MPG based on an aircraft's typical cruise speed and fuel consuption. A Cessna 182 Skylane gets about 10-12 gallons per hour (depending on engine) while cruising at 110 knots -- or about 120-130 mph. That makes 11-15 mpg, or about the same as a typical SUV, but twice as fast.
I once worked out that a Boeing 747, 2/3 full, gets about 60 passenger-miles per gallon. I don't remember the specifics of the calculation, but I imagine that was with 200 people on board (a nice round number), for a total of 3.3 gallons per mile in flight. That's just over a half a gallon per second, not bad considering the size of the beast.
Seriously: since they're being offered as rewards, they must be worth something -- but any geek worth his/her salt has his/her own domain and mx anyway.
Slashdot Mirror
I worked at General Atomic in the 1980s. At that time, they had a complete high temperature gas-cooled pebble reactor design, but were having regulatory troubles building and deploying one in the U.S.
Now the Chinese nuclear physicists will eat their lunch. Sorry, guys. Here's hoping that you'll finally get to build 'em here.
That word. I do not think it means what you think it means.
Well, certainly. That just means that mathematicians know precisely the thing about which they are talking (the "complex numbers" has a very precise meaning, to someone who has followed the formal definition of the set). Since the Riemann hypothesis deals with functions defined on the set of complex numbers (and limits of functions), it is very precisely posed.
I will not go through the exercise of proving so here, but there really isn't any way to come up with more than one answer, without speaking of something other than the usual complex numbers.
You "...could say that numbers are actual entities, and that there is an actual set of complex numbers that exists in some sense
See some of the definitions online...
``Magnetic motors'' - bah. They don't conserve energy, so most rational people don't believe in them. I've analyzed a few designs myself, for fun when I was a gradual student. There's always some little mistake the inventor made, where the power gets lost. Then, when you point it out, they get angry at you for spoiling their perfect idea.
The whole point of the halting problem is that there are computational sequences of all lengths (including aleph-null) that are irreducible. You can't know the result of such an irreducible sequence unless you've run through a certain minimum number of logical steps. In some sense, you can't know the answer to an irreducible computing problem unless you've brute-forced the answer already.
Saying "of course it's decidable -- either program A or program B is the correct answer" is not legitimate. The whole point of the halting problem is that it's impossibly hard to decide which (of A or B) is the correct answer in all cases. There are a few cases for which you'd have to wait literally forever.
Of course, there's a very large class of computations that are in fact decidable. In a lot of cases, it's enough to say "this halts in less time than X" or "this doesn't halt in less time than X", for a finite value of X.
That made turbine engines impractical for the last four decades -- but a turbine might be just the ticket for a series hybrid car. The batteries then become a power conditioner / load leveler that isolates the turbine from the wheels better than any transmission could...
In fact, for a while I considered doing exactly what the article suggests -- making my existing car (a VW microbus) into a series hybrid. My idea was to pull the engine (but not transaxle) and adapt a series-wound DC motor to the transaxle. Then put a small deck on top of the motor (about where the normal shrouding goes) and stick either a commercial generator or a small aviation APU on top of it (where the carburetors and other ancillary crap for the VW engine would normally live). There's enough room on either side of the engine comparement to hold about a dozen car batteries, with a custom rack mount (I was planning on UniStrut, the Erector set for grown-ups). Supporting all that weight was an issue -- but you can buy heavy-duty torsion bars that would support it all.
Then I gave my van to a starving artist and bought a Prius. Haven't looked back.
The problem I see stems from the dwindling world supplies of petroleum. There just isn't enough oil to burn at cheap prices, to power all those skycars. On the other hand, there's (comparatively) a lot of uranium around.
Over the next 50 years, unless renewable, portable fuel (e.g. fuel cells together with solar or nuclear electrolysis plants) become insanely cheap, the name of the transportation game will be "efficiency". $40/barrel oil may seem expensive now, but in another few decades it'll seem insanely cheap.
In practice, it would be quite difficult to extract those 75 mg of uranium from the tonne of coal, making coal about a suitable as cola for uranium ore -- but AJWM has a point that fly ash (which presumably contains precipitatable uranium oxide) might be a good ore.
Xe-135 is destroyed when it absorbs a neutron. So in an operating reactor is it "burned" rapidly as it is produced. But when you shut off the reaction, Xe-135 levels rise over the next eight hours to a peak level and then decay. This makes it very difficult to start a power reactor eight hours after you shut it down: the Xe-135 acts like an additional control rod, damping the reaction. You find that you have to pull the control rods much farther out to get the reaction started.
There's a problem with that: as soon as you get the reaction going in the core, the Xe-135 will rapidly "burn" off, restoring the usual control laws. That is dynamically unstable, as more neutrons -> less Xe-135 -> more reactive core -> even more neutrons!
The operators should have known what was happening when the found they had to pull the rods much farther than expected in order to bring the reactor stable "zero"-power operation ("zero-power" operation means that a chain reaction is being sustained but is not producing a significant amount of power. It is an important first step in operating the reactor: you start the reaction going, demonstrate positive control, calibrate your control settings, and then proceed to the power level you want. In the reactor where I worked, 5 watts of power, out of a rated maximum of 250 kilowatts, was considered "zero power".).
That unstable positive coefficient (as the Xe-135 burned off) made the reactor spike rapidly in power to a high thermal level -- where the reactor's positive void coefficient [what the Muerte23 described in the parent article] took over. That is a poor element of reactor design -- the Chernobyl reactors were "over-moderated". Fission neutrons come out fast, but uranium absorbs neutrons best when they're moving slowly. So you put the reactive material in a medium (water or graphite or Zirconium hydride or whatever) that will absorb energy from the neutrons without absorbing the neutrons themselves -- they bounce around, losing energy, until they can be absorbed by the core. Too little moderation, and the core won't start up. Too much moderation, and the neutrons will get absorbed and the core won't start up. The Chernobyl reactors were over-moderated, so that small voids in the graphite/water matrix in the core would increase the reactivity of the core. That's just stupid -- properly designed reactors are under-moderated, so that if the water boils the reaction tends to shut itself down.
Anyhow, all that would be moot except that the operators had disabled the main reactor shutdown mechanisms -- they couldn't SCRAM (or rapidly re-insert the rods into the core), but were forced to rely on the much slower drive mechanisms -- which couldn't contain the reaction. A rapid-drop SCRAM system existed (and would have saved the facility) but had been disabled for testing.
The problem (as I see it) with nuclear power is that people are such fuckin' idiots. Reactors are completely safe around people with what is called "common sense" but unfortunately, common sense isn't. Eventually, pointy haired bosses and Joe Sixpack rule the day.
(BTW, I hold a no-longer-current nuclear reactor operator's license).
Fissioning U-235 releases about 200 MeV/fission, or about (2e8 eV/fission)(1.6e-19 J/eV)(6.02e23 fissions/235 g)(0.075 g) = 6e9 Joules per tonne of the more enriched coal. That's about 1.6 megawatt-hours of heat, that can be derived from fissioning the U-235 in a tonne of coal.
Bituminous coal has an energy density of combustion of about 25e9 Joules per tonne, or about 7 megawatt-hours of heat from burning a tonne of coal.
At first glance, the combustion seems to win, especially when you consider that you can only get about 10% of the energy out of the uranium without reprocessing. But if you use the U-238 too (to make plutonium, which will then also fission in a conventional reactor), you get about 100x as much energy as from fissioning just the U-235. Of course, that takes reprocessing the fuel at least once, which is energy intensive, and there will of course be losses in the system. So maybe you only win by 30x. The fission should yield about 50 megawatt-hours of heat in a proper breeder-reactor setup. That's more than ten times the heat of combustion. Even "crappy" coal with only 1.5ppm of uranium in it could match the energy of combustion.
Wow.
That is to say, how could a hypothetical masturbating guy in a car possibly do any harm to me in my apartment (other than by sucking a bit of bandwidth)? So long as I don't have to see whatever twisted headphone-fetish images he's downloading, why should I, the hypothetical wifi-owner, care?
Hmm... there's an interesting trade-off there. Illuminating your dials with red is a good way to preserve night vision for driving -- but illuminating them with blue is a good way to keep you from having to re-focus too much. Because of dispersion in the eye's lens and cornea, nearly everyone is quite nearsighted in blue. So you can see blue-illuminated gauges in the near field, and then flick back to normally-illuminated streetscape, much quicker than you can look down at (and focus on) a set of red gauges. That probably doesn't matter so much for young drivers, who still have flexible lenses -- but aging drivers whose eyes take longer to focus might actually prefer dim blue illumination to brighter red illumination, despite the blue's effects on night vision.
Assuming that you mean "...this doesn't change anything related to free software at all", rather than "...this doesn't create any free software at all", you wanted to use "affect" here instead of "effect".
Remember: If Bob effects chocolate cake, he is making serviceable chocolate cake. If Bob affects chocolate cake, he is causing change in the cake. (Time to check Strunk and White...)
Most folks don't realize, but there really are four primary colors. Most geeky types are familiar with the red, green, and blue cone cells in our eyes -- but the rod cells that are used for night vision have their own separate response spectrum, weighted heavily toward the blue/violet end of the spectrum.
That means you have four separate "detector systems" in your eye, each of which is sensitive to a different slice of the optical spectrum. In particular, you can distinguish shades of violet and magenta that differ only in the blue-cone/rod response levels.
Ever think about why blue light is used universally to signify "darkness" or "moonlight" on stage? It's because, in low light levels, your cones shut down and your rods -- which in bright light connote blueness -- are the only part of your retina that works well.
It's also the reason why night-vision flashlights are red, and why blue LEDs appear so bright when used as flashlights. The red light doesn't stimulate your rods, preserving their sensitivity; and the blue light gives you extra rod stimulation per unit power, making blue LEDS very efficient as nighttime illumination.
Ever looked at CPAN?
On the other hand, if all you need is perl modules (no external libraries) then you can use the CPAN module itself to reach out to CPAN, get the perl code, and test it right there on your system. nearly all the time, it just plain works. That is amazing (to me, anyway).
>"C#"
You misspelled "INTERCAL".
- read it now
- read it later
- lend it to my friends
- give it to my children to read
- run textual analysis on it
- write in the margins
- read it on any device that I own.
I don't trust a DRM program to allow me to do those things, especially if my DRM e-book hardware becomes obsolete or breaks. And I don't want to risk going to jail for cracking my own damned copy of the book. (DMCA).One might argue that DVDs don't have those things, and were adopted anyway. But DVDs have several things going for them that ebooks do not:
Until e-books are available with either no DRM at all or minimal DRM, I probably won't be buying into them. It's just too annoying to not have control of my own data.
Would you keep using a bank where stories like this kept cropping up? I thought not.
PayPal is useful for amounts up to what you would willingly lose in a poker game -- but for any more serious amount of money, they suck.
Blue lights being out of focus (especially at night) is normal. It is due to dispersion in your eye, and it is a normal phenomenon. The materials that make up your cornea and lens have a higher index of refraction for blue light than for red and green, so you are more nearsighted in blue light than in anything else. The difference is of order 1-2 diopter between red and deep blue/violet. So if your vision is perfect for distant green lights, you can expect to focus slightly closer for red lights (but probably won't notice) and you can expect not to be able to focus for blue lights. The effect is stronger at night, because your pupil is open and the depth-of-field of your focus is much less.
You probably didn't notice that effect when your correction was -5.5, but now that it's 0, it's obvious.
My catchall gets over 2,000 spams a day, mostly from cretins on fishing expeditions for valid accounts.
I once worked out that a Boeing 747, 2/3 full, gets about 60 passenger-miles per gallon. I don't remember the specifics of the calculation, but I imagine that was with 200 people on board (a nice round number), for a total of 3.3 gallons per mile in flight. That's just over a half a gallon per second, not bad considering the size of the beast.
Seriously: since they're being offered as rewards, they must be worth something -- but any geek worth his/her salt has his/her own domain and mx anyway.