Slashdot is powered by your submissions, so send in your scoop


Forgot your password?

Comment Two anecdotes (Score 5, Insightful) 929

First - My work place was on the 3rd floor overlooking a main post office. I remember a case where someone left his groceries when he picked up his mail from his mailbox. About 20m later, we saw the guy sprinting back a few blocks down the street. However, the bomb disposal people were at ground level... and their robot shot his bag before he could get close enough for them to see him. Veggies everywhere. So no, this isn't picking up on someone in particular. Leave a bag unattended in a sensitive public place, and this may happen to you - regardless of who and what you are.

Second - I am sure this girl had a most unpleasant time. She is overlooking the fact that she wasn't a suspect as such. If you were a terrorist trying to smuggle a bomb into a high security area, a good way would be to plant it on some young, sympathetic, naive, idealistic western girl who is "obviously" not a terrorist - a profile this girl fit to a T. To rule this out you need to ask a lot of invasive, personal, seemingly irrelevant questions. If this sounds far fetched to you, read about who planted a bomb in his pregnant Irish fiance's bag. I am certain she went through a most unpleasant time as well. I am also certain she appreciated keeping her and her baby's lives. I am also certain all the other passengers on her flight appreciated continuing living, too. And the crew. And all their families. And friends.

The bottom line is that security in Israel is different from the USA. Instead of inflicting ineffective, mindless, low-level nuisance on everyone, it focuses on people who may (knowingly or unknowingly) pose a risk and gives them a thoroughly unpleasant, but effective, screening. This method works. And for most people, Israeli security is a much more pleasant experience than going through USA security. Of course, for the few who end up getting the 3rd degree, it is much worse.

Comment Proproetary systems are holding GPS back (Score 1) 177

Why can't I push a button on my cell phone and send my location to the phone of whoever is on the other side of the line? Have locations as part of the contact information in my address books? Push a button on my phone to save the current location in a contact? Use bluetooth to send a location (or even just an address) from my phone to my car or hand-held GPS so I can navigate to it? Have one GPS software to run on my Netbook that will work in the USA, Europe, Israel, Russia and China? Even when not online?

Maintaining maps is costly, for sure. But it is a cost that the government already spent using your tax money. If you think about it, it is insane to have multiple companies map the same roads and cities from scratch. At some level all the companies start with the same (tax paid) database and just tweak and update it. It may take a decade or two but eventually "free" (tax paid) maps will finally force GPS companies to focus on something other than charging money for basic maps, such as actual useful every-day functionality (and possibly specialized map layers).

Comment Karatand! (Score 4, Interesting) 285

Get a (thick?) glove fill with the stuff. Possibly have the external layer contain some inserts... You can now break sticks and stones - and bones - with impunity. The original concept and the name "Karatand" appear in "Stand on Zanzibar" by John Brunner. It seems you can use 3do as an approximation:

Comment Change the terminology (Score 2, Interesting) 365

Instead of talking about false positives and negatives and dependent distributions (which fly right over the head of the average joe), boil it down to the "amplification power" of the test. A random person "presumed innocent until proven guilty" has a chance of 1/3000 to be a terrorist. If you apply your 90% test, people failing it will be terrorists ~1/333 of the time. So the test as an "amplification power" of ~9x. Now everything becomes intuitive. You are looking for a 1-in-3000 needle in a haystack with an amplification power of ~9x, you now need to look for a ~1-in-333 needle in a haystack. The term "90% accuracy" doesn't appear anywhere to confuse things, and it is something everyone can easily grasp. And yes, I know, this ignores the terrorists false negatives; for that you say the test has a "miss rate" of 1/9 so about 1 in nine terrorists will slip through. These three numbers - (1) how rare what you are looking for is, (2) what's the "amplification power" of the test, and (3) what is the "miss rate", give you enough info to intuitively convey all you need to get a good feel for how effective the test really is.

Comment Servers in the sky (Score 1) 204

The idea is to launch a lot (zillions) of tiny (grams) solar-powered servers to orbit. This means you have no power of cooling issues. It sounds pretty crazy on the face of it, but if it costs ~$1G to build a data center, it may actually be economical. There are a ton of practical issues, of course - the site goes into them in some detail.

Comment Re:Forever War is fantastic (Score 2, Interesting) 296

Heinlein pretty much posits that all wars are a matter of population growth and limited resources.

This is so weirdly Malthusian, particularly coming from a technological optimist like Heinlein, that I never bought into it.

Heinlein tries to pretty up various completely irrational ideas as to why people fight to make it seem inevitable, but the only one that made sense to me was at the individual level. The rest amounted to, "Eventually we will meet something that wants to fight us, and we'd better be ready"--the H&MP instructor says almost exactly that at some point. And we will meet something that wants to fight us because "that's the way the world is."

A point often lost on people is that memes share the same Malthusian crunch as biological creatures. In fact, memes may face a stronger crunch. Technological advances may keep us feeding larger populations, for a while anyway... but nothing will create sufficient brains for the memes to populate without "meme wars".

Some memes engage in "limited warfare", accept their losses gracefully, and fade off the scene. Some drive their hosts to fight to the death and try to convert as many others as possible. Guess which type of meme tends to survive longer in the human population?

If this sounds academic to you, open a history book. "Why don't we all just get along" sounds great in theory, and is certainly the purely rational-economic point of view. But when asked to convert to Islam, or get baptized, or pay taxes to a government overseas, or some other "meme only" change that has little or no physical effect on you... People are most emphatically not pure rational-economic machines. People have culture (memes) and a little thing such as forbidding/allowing/forcing girls to wear a veil to school causes them to react "irrationally".

And this doesn't even go into the fact that, when all is said and done, Maltus was right on the money. Advancing technology aside, if the human race continues to grow exponentially, very quickly (in a millenium or two) you reach absurdities. Asimov calculated that if we double the number of people every 30-40 years, the total mass of humans will equal the total time of the universe - before the year 7000. Even if we double the number of people every 100 years instead of 30, it takes an alarmingly short time for people to eat the whole of the earth (molten core and all).

At some point, the number of deaths must balance the number of births. Sure, rich countries are getting close to that point, but the western world as a rule is not there yet, and its doubtful it ever will be. You also have a problem with the poor-but-developing countries who have access to modern medicine and are making babies like crazy. If people are willing to react violently to the amount and placement of fabric on school girls, you can imagine how they'll react when not/having babies comes into play. You'll be fighting the Catholics and the Muslims at the same time. And that's just for starters.

Finally, in the 10,000 years of documented history of this planet, there hasn't been a single one AFAIK when there wasn't some war going on somewhere. This seems a pretty strong indication that war isn't going anywhere. The meme "why don't we all just get along" just isn't working that well, and saying that it will some day take over the world takes a whole lot more justification than "Maltus was wrong because of the last 400 years". First, we had plenty of the most nasty imaginable wars in the last 400 years, and second, they were extremely atypical.

Heinlein was a technological optimist but he was no fool either. If anything, his explanation for the war seems much more realistic than Haldeman's. In Heinlein's universe, humans and "bugs" and other races could live on the same planets, and assuming such planets are in very finite supply, you have all the makings of a nasty war. Also, Heinlein makes some philosophical points there about why people would choose to become soldiers, and why would a society encourage or even be built on this (as many have in human history), which are worth thinking about (whether you agree or not).

Haldeman's humans and aliens started fighting for no good reasons ("a ship was lost to an accident, an alien ship happened to be around, and some generals polished their medals and declared war" - yeah, right) and then stopped for no good reason ("it is a clone thing"). His soldiers are either conscripted or grown for the job (no choice involved) and are completely divorced from the society (this is in fact a main theme of the book). The whole thing is so weak that the only consistent reading of it is that the protagonist doesn't get to know the reasons behind the war started or stopping. He's just a pawn with no choice; what's more, he never in the whole book stops to think about it - not ever! Heinlein's protagonist spends most of the book thinking about how and why he got to be where he is!

That said, both authors did a great job describing an individual-caught-in-a-war point of view. Granted this point of view is different - Heinlein's is "What is good about being a Marine in WWII" (and they were all volunteers to the corp) and Haldeman's is "What is bad about being Infantry in Vietnam" (minus the "this is a stupid politician war" bitching that draftees were certain to share). But both do a great job at it, and are definitely worth reading.

Comment Re:So what next? (Score 1) 522

Charge a fee. It doesn't have to be money. It could be cycles.

Have the client hash the message append some random characters to the end of the message. Have it change vary the characters until the hash matches some pre-defined pattern before sending. Cheap to verify on the incoming machine (just one hash), arbitrarily expensive on the sending machine.

Beautiful; you can even write the code in Javascript so all humans will notice is a <1s delay when pressing the "submit" button".

But - the spambot can simply bombard you with all the possible suffixes, letting your servers pick the one that is correct (and melting your CPUs while at it).

You'll need to restrict the number of retries for the same message, so they'll have no recourse other than simply tacking some random bits at the end and hoping to hit the jackpot. At this point it becomes a balance act between the amount of CPU the spammer is willing to invest, and the amount of time a valid user is willing to wait.

Whether there is a sweet spot that drives spammers away and keeps users in depends on the relative cost of CPU for users and spammers. Now, even if spammers steal their CPU from zombies, it isn't "free" - they may move on to a site that cheaper to hack. But it is still pretty cheap...

It would be very interesting to see some site trying it in practice.

Comment Welcome to the 60s (Score 2, Insightful) 217

Look up "TEMPEST", e.g. in - this isn't merely "old news", this is "so ancient it dates before I was born", and I am old enough to have used punch cards.

This is why some computer rooms will never contain wireless peripherals or wireless networks or Internet connections; but will have an intimidating sign on the door, and combined biometric/keypad entry, and Faraday cages built into their walls, and a self destruct mechanism, and fences around them, and 24/7 armed guards, and a hot line to a fast-response team on a separate near-by base.

For everyone else, well, when you buy tinfoil rolls, remember to buy enough for your hat _and_ your peripherals cables :-)

Slashdot Top Deals

In the future, you're going to get computers as prizes in breakfast cereals. You'll throw them out because your house will be littered with them.