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Comment: Re:How did this get modded up (Score 1) 187

by jcrb (#47389807) Attached to: Train Derailment Dumps Two 737 Fuselages Into Clark Fork River

You can't prove a negative

It's called proof by contradiction.

No you have it backwards, proof by contradiction is a method of showing something is true by showing that if it were false it would be a contradiction with something known to be true. An example in this case would be to say,

"assume there are purple unicorns, that would imply through a chain of logic that there can not be pink spotted elephants, since we know that pink spotted elephants do exist then purple unicorns can not exist, QED"

since you are likely to have difficulty finding a contradiction that results by assuming that purple unicorns do exist this method of proof it unlikely to helpful in this case.

Comment: Re:Warranty (Score 2) 187

by jcrb (#47389725) Attached to: Train Derailment Dumps Two 737 Fuselages Into Clark Fork River

What the fuck?

The illegibility that you find so shocking would seem to come from the terminal the poster is using (based on their previous comments) the content would seem to come from the fact that all they appear to want to do is assert that various political view points are bad along with those who hold them regardless of how relevant it might be to the discussion at hand.

Or their views on the world may just be the result of living in Seattle and not having sex for 20 years, can't tell which is the cause and which is the effect.

Comment: Important work - gives handle on earth's dynamo (Score 4, Insightful) 80

by Cliff Stoll (#47298935) Attached to: Satellite Swarm Spots North Pole Drift

This is important work, which compliments terrestial geomagnetic measurements and space based observations.

The earth's magnetic field results from a planetary dynamo. Magnetic field lines get frozen into the electrically conductive fluid core. Then, differential motions in the fluid causes the magnetic field to get twisted up -- it's no longer is the simple dipole (like those bar magnets that you played with as a kid). Instead, the earth's magnetic field develops high order moments (sorta like bumps and dips). These shapes evolve as the conductive core moves. Eventually, the magnetic field gets so tangled up, that it unravels. At that time, the earth's field reverses. These magnetic field reversals show up in the geologic record ... every 10,000 to 100,000 years, there's a flipover.

Measurements like the ESA Swarm satellite give us a handle on the evoloution of the Earth's magnetic field, as well as showing how that field interacts with the magnetic and particle environment of the solar wind.

(disclaimer - most of what I just posted is from a terrific graduate class that I took at the Lunar & Planetary Labs way back in 1979, and when I worked with Charles Sonett, who studied the solar wind. Likely, much of this is way out of date!)

Comment: Re:Well, yes, I was there... (Score 1) 120

by Cliff Stoll (#47182183) Attached to: Whom Must You Trust?

And my thanks back to you, oh Anonymous Coward: The 15 cents in royalties from your purchase of m'book is now helping my kids attend college. Uh, it'll last about 1.3 minutes.

You say that you're managing firewalls - all sorts of possibilities! I had the honor of working with Van Jacobson at LBL when he first researched TCP/IP traffic jams and compression. I was amazed at how much could be done by looking at traffic and thinking about the interaction of traffic, buffers, routers, and network congestion. Wonderful stuff - what looks like a boring problem may be an opportunity for research.

With that in mind, here's my encouragement to you: Go and sharpen your tcpdump & wireshark tools. Figure out what's really happening to those packets. Who knows what you'll uncover?

Comment: Re:IF you are the REAL Cliff Stoll? (Score 1) 120

by Cliff Stoll (#47182047) Attached to: Whom Must You Trust?

(blush). Thanks!

Now it's your turn: Go forth and make our networked community friendlier, stronger, more trustworthy, and more useful.

Best wishes,
-Cliff

PS: Of course, you raise a fascinating, self-referential question. How can you tell if this posting is from the real Cliff Stoll? I know it's me - and it's easy to prove in person, but difficult online. For the best proof, well, stop by for coffee. Way more fun than posting online.

Comment: Well, yes, I was there... (Score 5, Interesting) 120

by Cliff Stoll (#47181593) Attached to: Whom Must You Trust?

It's been a quarter century since I chased down those hackers. Hard to think back that far: 2400 baud modems were rarities, BSD Unix was uncommon, and almost nobody had a pocket pager. As an astronomy postdoc (not a grad student), I ran a few Unix boxes at Lawrence Berkeley Labs. When the accounting system crashed, my reaction was curiosity: How come this isn't working? It's an attitude you get from physics -- when you don't understand something, it's a chance to do research. And oh, where it led...

Today, of course, everything's changed: Almost nobody has a pocket pager, 2400 baud modems are a rarity, and Berkeley Unix is, uh, uncommon. What started out as a weirdness hiding in our etc/passwd file has become a multi-billion dollar business. So many stories to tell ...

I've since tiptoed away from computer security; I now make Klein bottles and work alongside some amazing programmers at Newfield Wireless in Berkeley. Much fun debugging code and occasionally uncorking stories from when Unix was young.

Warm cheers to m'slashdot friends,
-Cliff

Comment: They only had no idea because they didn't look (Score 1) 653

by jcrb (#46526951) Attached to: $30K Worth of Multimeters Must Be Destroyed Because They're Yellow

If you go to the USPTO trademark search and put in "multimeter and yellow" the FIRST result is a Fluke yellow multimeter.

If you are in the business of making multimeters and claim you have never heard of Fluke or seen one you are clearly full of it.

Company caught clearly knocking off other company's product tries to play the "trademark laws is bad, boo hoo" card.

Not impressed

Comment: Re:Wasn't this a movie? (Score 1) 237

by jcrb (#46129307) Attached to: Now On Video: GCHQ Destroying Laptop Full of Snowden Disclosures

No you misunderstand the nature of recovering data from a HDD. It s not that the data from the 49th overwrite could be recovered, it is that the data from the 1st write might be recoverable. How is it that the data from the 1st write could be recovered but the data from the most recent couldn't be? Because if the 1st write sits for a long time then 1 that was written to the drive when over written by a 0 becomes not a 0 but a 0.1 or the 0 overwritten by a 1 becomes a 0.9 not a 1. so while the drive itself is not going to be able to recover anything if you just write 0's to the whole drive, someone with better equipment that is prepared to read the drive over and over may be able to sift out the 0's and the 0.1's as if they were 0's and 1's. So by randomly writing 0s and 1s back and forth you give all the bits a randomized amount of magnetism and make it unrecoverable.

So if the disk had one set of data stored on it for an extended period of time and then you wrote a new set of data there would be a period of time where you could 0 the drive and potentially recover the first set of data, so at most you could say the drive contains somewhat less than 2X its rated capacity, with great difficulty.

Comment: Think of the children!!!!! (Score 1) 22

by jcrb (#46126005) Attached to: Meet the MOSS Modular Robots (Video)

I'm sure the government will step in and protect us from these products just as they did with Buckyballs.

Buckyballs were sold as adult office toys and the Consumer Product Safety Commission still felt the need to save the children from swallowing the ball magnets. Given that these say they are for ages 8 and up I don't think they stand a chance... which is sad because they certainly look like they could be a lot of fun.

Clearly what they need to do is include an "Emergency Extraction Super Magnet Rescue Tool" (that is too big to swallow) with each set along with a DVD copy of the movie Fortress, and print "Rescue Tool Instructional Video" on the DVD, and then they should be good to go.

Comment: Sadly (Score 5, Insightful) 383

by jcrb (#46090411) Attached to: Congressmen Say Clapper Lied To Congress, Ask Obama To Remove Him

It's not a "lie" if they aren't convicted, and even then for most people it will still be a "misstatement".

The win at all costs nature that American politics have turned into as of late have made seeing just how blatant a lie you can get away with part of the game rather than something to be avoided.

Asking nicely for his removal will accomplish nothing at all. Either go for conviction or don't bother. Saying "he's not nice and we don't like him anymore" is not going do anything other than cause the administration to chuckle.

panic: kernel trap (ignored)

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