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Comment Re:Many a young engineer.... (Score 2) 72

... every schematic drawn by every semiconductor engineer got the arrow backwards.

As I heard it, The arrow is "backward" because Benjamin Franklin, when doing his work unifying "vitreous" and "resinous" electricity as surplus and deficit of a single charge carrier (and identifying the "electrical pressure" later named "voltage"), took a guess at which corresponded to a surplus of a movable charge carrier. He had a 50% chance to assign "positive" to the TYPICAL moving charge carrier in the situations being experimented with (charge transfer by friction between different substances, currents in metallic conductors, and high voltage discharges in air and water-in-air aerosols) and happened to guess "wrong".

Thus we say electrons have a negative charge, "classical current" corresponds to the sum of the flow of moving positive charge minus the flow of negative charge (i.e. the negative of the electron current, which is all there is in normal-matter metallic conductors), the arrowhead on diodes (and junction transistors) points in the direction of classical current across a junction, and so on.

But though it's the charge carrier in metallic conduction and (hard) vacuum tubes, the electron ISN'T the only charge carrier. Even in the above list of phenomena, positive ion flow is a substantial part of electrical discharge currents in air - static sparks and lightning. Positive moving charge carriers are substantial contributors to current as you get to other plasma phenomena and technologies - gas-filled "vacuum" tubes (such as thyratons), gas an LIQUID filled "vacuum" tubes (ignatrons), gas discharge lighting, arc lighting, arc welding, prototype nuclear fusion reactors, ...

Move on to electrochemistry and ALL the charge carriers are ions - atoms or molecular groups with an unequal electron and proton count, and thus a net charge - which may be either positive or negative (and you're usually working wit a mix of both).

And then there's semiconductors, where you have both electrons and "holes" participating in metallic conduction. Yes, you can argue that hole propagation is actually electron movement. But holes act like a coherent physical entity in SO many ways that it's easier to treat them as charge carriers in their own right, with their own properties, than to drill down to the electron hops that underlie them. For starters, they're the only entity in "hole current" that maintains a long-term association with the movement of a bit of charge - any given electron is only involved in a single hop, while the hole exists from its creation (by an electron being ejected from a place in the semiconductor that an electron should be, by doping or excitation, leaving a hole) to their destruction (by a free electron falling into them and releasing the energy of electron-hole-pair separation). They move around - like a charge carrier with a very short (like usually just to the next atom of the solid material) mean free path.

For me the big tell is that they participate in the Hall Effect just as if they were a positive charge carrier being deflected by a magnetic field. The hall voltage tells you the difference between the fraction of the current carried by electrons excited into a conduction band and that carried by holes - whether you think of them as actual moving positive charge carriers or a coordinated hopping phenomenon among electrons that are still in a lower energy state. Further, much of interesting semiconductor behavior is mediated by whether electrons or holes are the "majority carrier" in a given region - exactly what the hall effect tells you about it.

So, as with many engineering phenomena, the sign for charge and current is arbitrary, and there are both real and virtual current carriers with positive charge. Saying "they got it wrong" when classical current is the reverse of electron current is just metallic/thermionic conduction chauvinism. B

Comment ...or the difference may be totally insignificant. (Score 1) 417

The marginal increase in the probability of an someone being a terrorist given that you know he's an engineer may be startling in relative terms, but in absolute terms it's insignificant.

Estimates of total active membership in terror groups worldwide is under 200,000, but let's assume there's even million active terrorists just for the sake of having round numbers and not having to quibble over where to put the decimal point. There are seven billion people in the world, so the rate of terrorist participation in the general population is 14 thousandths of a percent; let's call that p(T), and call the probability that someone is a terrorist given that they're an engineer p(T|E). Let's look at the absolute marginal difference being an engineer makes, i.e.:P(T|E) - P(T)

i. p(T) = 0.0001428
i. p(T|E) = 9 * P(T) = 0.001286
iii. P(T|E) - P(T) = 0.001143

So being an engineer increases your chance of being a terrorist by at most about 1/10 of 1% under wildly pessimistic assumptions. In fact the marginal difference is really more like 1/50 of 1%. Now it's interesting that the rates of terrorism are so much larger among engineers than other people, but it has little practical significance and being an engineer myself that's what I'm most concerned with. If you were designing a surveillance program and were picking out groups that need keeping tabs on, 1/10 % is a grasping-at-straws number

Comment Re:Vacuum tubes handle EMP's better (Score 1) 72

"No point progressing since the bombs are gonna fall any day now. Then where will your fancy silicon highways and databases be?"

Given that the Internet Protocol and much of the rest of the networking technology that still underpins the Internet were developed as part of a cold-war program to create a communication system that could survive a nuclear attack that destroyed most of it, and still reorganize itself to pass messages quickly, efficiently, and automatically among any nodes that still had SOME path between them, your post seems to come from some alternate universe to the one I inhabit.

Comment Re:what happened with computers? (Score 1) 238

If rockets were in any way physically analogous to computers, a Saturn V today would be the same height as the width of a human hair and still lift...

And Armstrong's famous footstep speech would be hacked and replaced by a plug for boner-pills.

"If you want a giant leap in your trousers..."

In short*, be careful what you ask for.

* No pun intended

Comment Re:what happened with computers? (Score 1) 238

now the military is buying the same tech as everyone else because it's better than their custom made stuff.

That's not entirely true. Often the difference is simply not enough to justify the huge price difference.

For example, a $500 "battle grade" hammer may be able to survive being run over by a tank during battle, but is that really worth the extra $460, or is it better to live with occasional flattened hammers and spend the $460 elsewhere.

Comment More than just money (Score 1) 238

During the age of Columbus, any schmuck with a ship could go out exploring.

No they could not unless they had the backing of someone wealthy to pay for the ships, equipment and salaries needed. However they were willing to pay for it because while it was expensive and dangerous they were motivated by a variety of things: hope of treasure to plunder, land to lay claim to and knowledge of distant peoples and creature to learn about.

It's a bit sad that someone who calls themselves a scientist thinks that the only reason anyone will ever do anything is purely for money. The ability to make money will certainly be what causes space exploration to take off in a big way but, as with any frontier be it in knowledge or on the map, the first explorers are often motivated by things other than how much money they will make...that tends to follow later.

Comment Let gamblers gamble (Score 1) 238

The practical current function of commercial space co's should be to provide routine transfer of staff and supplies to and from a station or base. That makes perfectly good sense. When something becomes a semi-commodity, private enterprise, with competition*, is usually more efficient.

If and when space does become profitable, such as asteroid mining, such commercial co's will already have some of the infrastructure and knowledge to pursue that market.

As far as pie-in-sky commercial endeavors like a one-way Mars mission, let investors waste money if they want. Who knows, maybe they'll stumble on an unforeseen way to make a profit. Surprises happen. If somebody discovers how to tame anti-gravity particles to get cheap launches, for example, existing space companies will have a big leg up. It's not irrational to devote some of one's investment portfolio on high-risk/high-reward stocks.

And even if they fail, humanity as a whole will be smarter for it, learning from their mistakes. Failure is experience.

* NASA does use lots of private contractors for current missions. But, they are mostly custom one-off products.

Comment Scientists trained to ask "Why?" (Score 1) 417

There is obviously a correlation between being dateless and becoming a terrorist.

It has to be more than that: computer scientists and physicists are not known for their terrorism or their dating (well unless it's radiocarbon dating).

Personally I think it has more to do with the fact that engineers are trained to follow rules and so it attracts people who are happy to follow rules without necessarily questioning them or completely understanding the reasoning behind them.

On the other hand scientists will question every rule you give them and even when they believe that the rules might be right they will still spend their time poking them to see if they really do apply everywhere....which is why we can be so annoying at times especially to those trying to use toxic, religious dogma to persuade others to commit irrational and immoral acts.

Comment More and faster options (Score 1) 171

The Internet generation expects easier choice, such as clicking on Favorites to go elsewhere on whim, and will not sit through long commercial breaks. Plus, gaming, social media/chatrooms, and cat videos compete for attention.

This may mean that TV shows are less profitable and have a smaller budget. But it could also mean that new lean and mean media companies will offer a wider variety and experiment more because they don't have to deal with the bureaucracy and oligopoly collusion of the big networks.

Comment Re:led by a president possibly insane enough to do (Score 1) 131

LOL! You gotta love these libs! So stupid, it's funny.

For something comparable, the tough talk of Iran's leader affects our decision makers here and now. His quotes are quite often used by the GOP to argue their stance.

Either GOP is heavily bluffing, or they would factor in his blustery talk if there were a related international issue that required a snap judgement.

It's not silly, as you imply, it's dead serious.

Comment John Wayne (Score 0) 131

U.S., then led by a president [percieved as] possibly insane enough to do it.

Yet another downside of electing Rambo wannabe's.

We were really lucky to survive the cold war, there were roughly a dozen or more close calls. Or, perhaps it's the Anthropic Principle, multiverses, and/or God (the server admin of our emulated universe) kicking in to save us.

I have a theory that it's impossible to prove anything, but I can't prove it.