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Comments

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Social Security Administration Joins Other Agencies With $300M "IT Boondoggle"

jeffb (2.718) A large IT project is late and over budget? (137 comments)

I've never heard of such a thing. Thank goodness Slashdot is here to challenge our preconceptions.

2 days ago
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Researchers Test Developer Biometrics To Predict Buggy Code

jeffb (2.718) This misses two of the biggest developer problems: (89 comments)

1) Arrogance. You know that average developers have a hard time with some kinds of code, but you're a superprogrammer, and you don't have those problems. If someone decides later that there's something wrong with your code, well, they should've gotten their requirements straightened out before they told you to go and build it. The only time you lose your cool is when you have to deal with idiot managers, analysts, or users.

1) Complacency. You've been pounding on this code forever, and you just don't care any more. Yeah, there'll be bugs, people will yell, they'll get fixed. That's just the way development goes. Why get worked up about it?

3 days ago
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AirMagnet Wi-Fi Security Tool Takes Aim At Drones

jeffb (2.718) Arguments based on drone range (52 comments)

It's possible to connect a controller to an antenna that vastly extends its range. Is your property extensive enough to give you a 2-kilometer perimeter around your house?

3 days ago
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AirMagnet Wi-Fi Security Tool Takes Aim At Drones

jeffb (2.718) I've got a similar idea in the works... (52 comments)

It's a receiver to detect the EM signature from the onboard electronics of a Prius.

See, I've heard that it's possible for a Prius driver to run over kids who are playing in the street. So I've designed this receiver that fits into a kiddy backpack, and sounds an alarm when there's a Prius nearby. That way, when my kids are playing in the street and a Prius approaches, they'll hear the alarm. I guess then they can get out of the street, but what I'm really looking for is a way to ban Priuses from driving on my street. After all, I'm a responsible parent who's keenly aware of the dangers Priuses pose to kids who play in the street.

4 days ago
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Verizon Boosts FiOS Uploads To Match Downloads

jeffb (2.718) And if you're in the vast FIOS-free zones... (230 comments)

...you'll be upgraded to pound sand with both hands.

North Carolina was promised FIOS "real soon now" for years. At this point, it's pretty clear that if you don't already have it, you won't be getting it. Google blimps, drones, and sewer lines will bring us high-speed broadband long before Verizon significantly extends their buildout.

4 days ago
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A Look At NASA's Orion Project

jeffb (2.718) Re:Old dreams (108 comments)

Well, if it tries to explode them out its nose, it doesn't go in the right direction.

5 days ago
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Cosmologists Show Negative Mass Could Exist In Our Universe

jeffb (2.718) Re:Negative mass is weird (214 comments)

Okay, as long as I've got you on the line... :)

What's supposed to happen when negative and positive mass collide?

If I throw a tennis ball at a wall, it bounces off (and the wall recoils imperceptibly). If I throw a negative tennis ball at a wall -- or throw it away, causing it to move toward the wall, whatever -- what happens when it hits? It seems like it would try to "recoil" in the same direction it was traveling, maybe even giving the wall a "tug" instead of a "push" when it hit. But it can't move forward, because presumably negative and positive matter can't simply interpenetrate -- or can they?

Gaah, so many microscopic/macroscopic behavior assumption violations...

about a week ago
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Cosmologists Show Negative Mass Could Exist In Our Universe

jeffb (2.718) Re:Negative mass- not antimatter, but odd (214 comments)

Negative mass is very diferent from antimatter. Antimatter is opposite to normal matter in charge and quantum numbers (such as baryon number, etc.), but still has positive mass.

Negative mass reacts oppositely to both gravity and intertia. Oddly, that means that negative mass still falls down in a gravitational field: The gravitational force is opposite, but negative mass responds negatively to force (a=F/m, where both F and m are negative). So negative mass particles repel each other gravitationally, but are attracted to positive mass objects.

Trying my best to ignore my intuition, which is heavily biased toward "all mass is positive":

A negative mass would fall down in a gravitational field (generated by a positive mass) -- it would experience a force directed away from the positive mass, and it would respond to that force by moving toward the positive mass.

However, the negative mass would repel the positive mass gravitationally -- effectively, exert a force directed away from itself -- correct?

It seems to me that if you had two equal but opposite masses in freefall, the negative mass would accelerate toward the positive, the positive would accelerate away from the negative, and the negative mass would chase the positive mass off the edge of the universe at constant acceleration.

It also seems like two negative masses would repel each other (exert a force directed away from each other), but respond to that repulsion by accelerating toward each other.

What am I missing?

about two weeks ago
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Brazil Nut Effect Explains Mystery of the Boulder-Strewn Surfaces of Asteroids

jeffb (2.718) Re:Explains the TV News (58 comments)

Still does nothing to explain the similar sorting of Slashdot comments, as illustrated in this thread.

about two weeks ago
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Phase-Changing Material Created For Robots

jeffb (2.718) "An' when they git ready..." (35 comments)

'... I say, when they git ready...... ever hear tell of a shoggoth?"

Terminator 2? Feh.

about two weeks ago
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Chemists Build First "Buckyball" Made of Boron

jeffb (2.718) Re:Boron? (39 comments)

Step 1: Build buckyball model out of wooden skewers and string.

Step 2: Wrap skewers in raw bacon.

Step 3: Microwave.

Step 4: Post to YouTube.

Step 5: Profit!

(Note to whoever actually tries this: Depending on the scale of your model, some of the bacon loops may resonantly couple with the field in your microwave oven. Don't be surprised at arcs and flames. Please don't skip Step 4.)

about two weeks ago
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Predicting a Future Free of Dollar Bills

jeffb (2.718) Re:Why? (753 comments)

That's not the way it worked for us. Overdraw charges? Sounds like you're talking about a debit card, not a credit card.

about two weeks ago
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Predicting a Future Free of Dollar Bills

jeffb (2.718) Re:Useless coins (753 comments)

No, "issued for circulation" means the Mint sends them to the Fed for distribution -- so they can be spent, given out as change, and so forth. The last few years of dollar coins haven't been issued for circulation. Yes, they're still legal tender, but since you have to pay more than face value to get them, it's kind of dumb to spend them.

Kennedy halves haven't been issued for circulation in years, either, but you'll still find recent-date ones in rolls occasionally. People inherit or steal them, don't care about collectable value, and just spend the coins or turn them in at the bank.

State quarters (and now America The Beautiful national park quarters) are issued for circulation -- at least, the ones minted in Philadelphia and Denver.

about two weeks ago
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Predicting a Future Free of Dollar Bills

jeffb (2.718) Re:Useless coins (753 comments)

Yeah, I think it's time for a full reset on our cash denominations. Knock out the cent and nickel (each one costs more than its face value to produce). Make dimes and half-dollars of the same general size and shape as today's cent and nickel. Make dollar coins like today's dime, and bring back the "eagles" -- quarter-eagle ($2.50), half-eagle ($5), eagle ($10), and double eagle ($20). Heck, you could even reinstate the half-union and union ($50 and $100), which never made it into circulation during the original 1850's gold rush.

But this will never happen. There's too much inertia around our current system, and by the time inflation trivializes all current denominations, the "cashless society" folks will most likely have won. Maybe the black and grey markets will go over to true hard currency, the silver and gold that's currently the domain of collectors and doomsayers.

about two weeks ago
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Predicting a Future Free of Dollar Bills

jeffb (2.718) Re:Useless coins (753 comments)

They're no longer issued for circulation. They're only made for collectors. This seems like an odd business for a government (manufacturing collectibles), but it does produce a small profit, so I guess there's not a lot of motivation for shutting it down completely.

about two weeks ago
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Predicting a Future Free of Dollar Bills

jeffb (2.718) Re:Why? (753 comments)

The thug prowling around in the woods can take and spend my $20s, and I've got no recourse unless he's caught. If he steals my credit cards, they're only good for him until I phone in the theft, and I'm out zero money in the end. Plus all that terrible OMG-Big-Brother-Ate-My-Privacy tracking can tell the police a good bit about where he's been and what he's been doing.

The Powers That Be have never frozen any of my accounts, but thugs have burglarized my house more than once. I have no desire to see cash go away, but it's disingenuous to claim that it's less risky than e-money.

about two weeks ago
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Biohackers Are Engineering Yeast To Make THC

jeffb (2.718) Re:Has the potential for extreme harm (159 comments)

That's got to be the weirdest "THINK OF THE CHILDREN!!!" argument I've ever seen.

about two weeks ago
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Biohackers Are Engineering Yeast To Make THC

jeffb (2.718) I've been calling for this for 20+ years... (159 comments)

Actually, I've been calling for someone to graft the THC-production complex into kudzu. That way, either we get government help to wipe it out, or the government finally gives up; either way, kudzu becomes useful for something.

Of course, I don't have much deep knowledge about GM or plant biology, so coming up with this idea was about on a par with saying "somebody ought to build a flying car". Here's hoping that the task these folks are tackling turns out more tractable than that one.

about two weeks ago

Submissions

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CES: Laser headlights edge closer to real-world highways

jeffb (2.718) jeffb (2.718) writes  |  about 7 months ago

jeffb (2.718) (1189693) writes "Audi will display laser-headlight technology on a concept car at the 2014 Consumer Electronics Show, joining BMW, whose plug-in hybrid should reach production in 2014. A November article on optics.org describes the technology in more detail. This approach does not scan or project a "laser beam" from the car; instead, it uses blue lasers as highly efficient light emitters, and focuses their light onto a yellow phosphor, producing an extremely intense and compact white light source and then forming that light into a conventional headlamp beam. The beam isn't coherent or point-sourced, so it won't produce the "speckling" interference effects of direct laser illumination, and it won't pose specular-reflection hazards. It's just a very bright and very well-controlled beam of normal white light.

HOWEVER, if multi-watt blue laser emitters go into mass production for the automotive market, it's likely to drive down their prices in other applications — for example, grey-market multi-watt "laser pointers". If you're looking for a tool to burn holes in the tires of drivers who offend you, this technology may indirectly help to fulfill your wish."
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Son of Therac-25: CT overdoses from "reset error"

jeffb (2.718) jeffb (2.718) writes  |  more than 4 years ago

jeffb (2.718) (1189693) writes "As the LA Times reports, 206 patients receiving CT scans at Cedar Sinai hospital received up to eight times the X-ray exposure intended. (The FDA alert gives details about the doses involved.) A misunderstanding over an "embedded default setting" appears to have led to the error. Human-computer interaction classes from the late 1980's onward have pounded home the lesson of the Therac-25, whose usability issues led to multiple deaths. Will we ever learn enough to make these errors truly uncommittable?"
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