Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?

Comment Re:Tech failed? (Score 1) 232

First of all, Agile doesn't work in every situation unless you stretch the definition to include non-agile practices where warranted. Second, the distinction between users and testers isn't as clean as you suggest. Users *are* testers until they become habituated to the system.

Comment Re:Tech failed? (Score 1) 232

Give that some systems are worse than others in inviting operator error, you can't just assume it's not the tech because operator error was involved. However even if the tech is as good as humans can possibly make it, that still wouldn't prevent operator error.

This kind of fault is hard to test for, because it's a non-functional requirement. You can't simply do a functional test and check off "prevent accidental message from being sent". At best you can simulate various scenarios, but those simulations are unreliable because you're dealing with testers, not people who are habituated to the system and who thus use it differently.

Clearly there were several kinds of operational faults here that may have been compounded by design flaws. But one of the operational mistakes was purely a matter of planning: not programming in a "false alarm" message to be sent after the inevitable operator error. This also suggests a design shortcoming in the system in that designers didn't anticipate the need to ever issue an ad hoc message on short notice.

Comment Re:Uforgiveable (Score 1) 232

I don't know. In my experience every design choice has unintended (although hopefully not unaccounted-for) consequences.

You have to add up all the foreseeable failure modes of a system with a mechanical switch -- including but not limited to a mechanical failure when you actually need to use it -- weighted by the probabilities of those failure modes. Just throwing a mechanical switch into a system because you had a failure is not engineering. In engineering you don't just focus on the desired result of a feature.

I'm not saying that a physical arming switch isn't the best option, but designing a solution to this problem is a job for someone with experience dealing with human factors in systems. I suspect having distinct armed/test modes is a good idea, but a switch alone isn't going to be enough, you'd need to have other indications the system is live -- e.g. klaxons and flashing lights.

Comment Re:Simple question (Score 3, Insightful) 59

Well, it makes lunar habitation feasible in the relatively nearer future.

Consider this analogous question: did the discovery of the cancer gene BRCA1 affect anyone at all? To your way of thinking, no, because it didn't immediately cure anyone's cancer. It only affected the lives of a very small number of cancer scientists by pointing them down promising avenues of research.

Comment Re:Inquiring minds want to know (Score 2) 225

Depends on the altitude of the blast. EMP is primarily produced by the interaction of gamma rays with the upper atmosphere. A single large warhead detonated at an altitude calculated for maximum casualties would almost certainly NOT produce the kind of EMP effects lazy thriller writers have taught the public are an inevitable part of any nuclear attack.

I know this because I've critiqued a number of science fiction manuscripts, and the "huge bomb creates the end of technological civilization" scenario is so popular as an inciting incident in crummy manuscripts that I actually did the research that the authors didn't do. The optimal profile for an EMP attack is a large number of small, non-thermonuclear atomic warheads detonated well above the stratosphere. This is not to say there would be *no* EMP effects of a ground level burst, but they're likely to affect long conductors like transmission lines, not the printed circuit traces in a transistor radio.

Comment Re: I was there... (Score 4, Informative) 225

Nope. The radius of destructive effect rises as the 2/3 power of yield. That's because the energy is dissipated in a three dimensional volume, and you're calculating the radius of intersection of that volume with a two dimensional surface. TL;DR: 20x the yield equals 7x the destructive radius.

Anyhow you can look up on the expected fatal radius by bomb type and yield, and the immediately fatal thermal effects of the warhead NK tested for an unprotected individual would be less than 5 miles, although many closer would survive because of shelter. Honolulu is about 12 miles across. If you put the warhead in the geographic center of the city to maximize casualties a lot of people on either end will survive. A lot of them will be uninjured too. The 5 psi blast radius is only three miles, outside that radius even residential buildings will still stand and people shaded by them will likely escape uninjured if they can get inside before the fallout.

Comment Re:Inquiring minds want to know (Score 3, Informative) 225

Baby boomer here. I remember when they taught this shit in school. Stay in your house, away from windows, keep curtains drawn. Have a battery radio and fill up containers with drinking water.

There are multiple ways for a nuclear strike to kill you: ionizing radiation burn, pressure wave, thermal radiation burn, firestorm, and fallout. Each has its own characteristic radius within which you will probably die from it, but your chances are improved by being inside.

You car would be a bad idea for many reasons unless it is in a garage. If your car is outside it will get quickly covered with very hot short-lived radioactive fallout. The gamma rays will cut through your car like it wasn't even there. You want physical distance to cut down your radiation dose until the hottest isotopes decay. The area in which the fallout will kill you quickly actually begins to contract after only an hour or so, even though the fallout is spreading. The area in which short exposures to fallout represents a health risk starts to drop after a day.

Get inside, stay inside, listen on the radio for the all clear.

Comment Re: I was there... (Score 5, Insightful) 225

The closest Hiroshima survivor was in a cellar only 300 m from ground zero -- which is very close when you consider that the bomb was detonated at 500 m altitude.

Now the device North Korea tested back in September was 10x to 20x more powerful than the Hiroshima bomb, but still if a bomb were detonated over Pearl Harbor and you were standing on the beach in Waikiki, you'd almost certainly survive, albeit possibly with thermal burns.

Here's the thing about all that Duck and Cover stuff from the 50s: when you're talking about a handful of bombs distributed over the entire country, diving under a picnic blanket actually makes sense. It wont' help you if you're at ground zero, but if you're five miles away or so it could make the difference between surviving uninjured or requiring hospital treatment. Multiply that by tens of thousands of people, and duck and cover type education is a sensible defensive strategy.

There is, however, a simple counter: attack with a lot more warheads. By the early 70s the Soviets had something like 25,000 of them. An all-out attack would not only result in multiple bombs falling on every city, it would guarantee the collapse of American society and a short and hellish existence for anyone unlucky enough to survive. Fatalism makes sense in that scenario. You might as well enjoy the show for a few hundred milliseconds and then die.

That's not where we are with a North Korean nuclear attack, not by a long shot. North Korea's arsenal is not large enough yet to cause the collapse of American society, or even to kill the majority of people in a city like Honolulu. So maybe we should be dusting off those old civil defense films.


Fake 'Inbound Missile' Alert Sent To Every Cellphone in Hawaii (chicagotribune.com) 225

"Somebody sent out a false emergency alert to all cell phones in Hawaii saying, 'BALLISTIC MISSILE THREAT INBOUND TO HAWAII. SEEK IMMEDIATE SHELTER. THIS IS NOT A DRILL'," writes Slashdot reader flopwich, adding "Somebody's had better days at work." The Associated Press reports: In a conciliatory news conference later in the day, Hawaii officials apologized for the mistake and vowed to ensure it will never happen again. Hawaii Emergency Management Agency Administrator Vern Miyagi said the error happened when someone hit the wrong button. "We made a mistake," said Miyagi. For nearly 40 minutes, it seemed like the world was about to end in Hawaii, an island paradise already jittery over the threat of nuclear-tipped missiles from North Korea...

On the H-3, a major highway north of Honolulu, vehicles sat empty after drivers left them to run to a nearby tunnel after the alert showed up, the Honolulu Star-Advertiser reported. Workers at a golf club huddled in a kitchen fearing the worst... The Hawaii Emergency Management Agency tweeted there was no threat about 10 minutes after the initial alert, but that didn't reach people who aren't on the social media platform. A revised alert informing of the "false alarm" didn't reach cellphones until 38 minutes later, according to the time stamp on images people shared on social media.

Comment Re:"Balky" (Score 1) 41

Words are like nice new wood chisels that get stored in a common work area. They don't stay sharp long because people keep misusing them.

"Balky" means "tending to refuse to respond as directed". If you have a car which often fails to start, that is a balky car. Balkiness is a tendency to a particular kind of malfunction, but the submitter here used it as a synonym for "malfunctioning".

Slashdot Top Deals

What hath Bob wrought?