Sisyphus

Not that I can see, no. You're implying causality? How very unscientific...

They’re both real. The reason they’re different “when one of them stops” is because starting and stopping involves acceleration, which means that the situation is not symmetrical. Take a look at the Wikipedia article on the Twins Paradox, which explains it in some detail in a few different ways: http://en.wikipedia.org/wiki/Twins_paradox Merged post follows: Consecutive posts merged But we do have all sorts of other "clocks," everything that happens in your body and mind that takes an amount of time. Which is to say, everything that happens in your body and mind. The reason light traveling back and forth is especially useful is because the speed of light is constant no matter what, so it’s a straightforward and reliable way to measure how much time is really passing, and because it’s a good way to show why time in different frames must be different.

"How can both be correct" isn't a meaningful question unless you give some apparent reason why they can't. This is because the "fast" observer has done all the accelerating.

It would be nice to think so, but I doubt it. Scientists and engineers that are politicians are still politicians, and leaders with those backgrounds haven't really stood out as ideal leaders. The only U.S. Presidents with engineering/science backgrounds are Herbert Hoover and Jimmy Carter (and arguably Thomas Jefferson, but by modern standards we'd call his education "liberal arts"). The only current world leader I can think of with training as an engineer is Mahmoud Ahmadinejad.

I don't think the stopwatch thing is really testing reaction time. You're not reacting to anything, you're just pushing a button twice. It would have to be one of you starting it and the other stopping. But that wouldn't really work either, since you wouldn't be reacting to the watch starting, you'd be reacting to the other's thumb starting to tense up and move. Maybe include a fake-out rule, where if the you hit the stop button when the other guy hasn't hit start you automatically lose? Of course, all of this is testing the reaction time of something you're entirely expecting at your peak level of alertness. You really want to test his reaction time, whip a tennis ball at his head from the side while he's eating breakfast.* *Note: By doing this, you assume full responsibility for all consequences.

Thinking about it again, it seems like a much bigger impact-related threat than stuff like tsunamis would be climate change. Much like a volcanic eruption, Tunguska caused a detectable decrease in atmospheric transparency for months afterwards all over the world. How much bigger would an impact have to be to seriously screw up the global climate? Obviously something 10km across would (that’s what caused the KT extinction, right?), but what effect would something, say, 100m across (1/millionth KT impact size) cause?

It seems like the main problem is that any black hole long-lived enough to be useful would be too long-lived to be safe and too massive to be able to be manipulated. And any black hole small enough to be safe and manageable would be so short-lived that it would be probably impossible to keep it in equilibrium by feeding it mass, and even if you could, it would give off way too much radiation. A black hole of appropriate size to supply all of the Earth’s energy needs would surely kill us all.

The terrorism threat with significant quantities of radioactive material is always dirty bombs. However, there would surely be few enough shipments that they could all be well-guarded, so theft is probably a negligible risk. Actually bombing a train carrying waste, however, could cause one hell of a mess anywhere along the transport route. How much of a mess and how likely it would be I'm not qualified to say. But dismissing it by saying "anything could be used as weapon" is rather disingenuous.

Actually, there are plants in Brazil, Argentina, and South Africa, with plans in the works in Chile and several north African countries (who would at least have the Sahara).

http://en.wikipedia.org/wiki/Fuel_efficiency_in_transportation

Well, I'm not an expert (so feel free to correct any flawed assumptions), and obviously there are various factors involved, but: The Tunguska event is estimated to have a seismic effect of about magnitude 5. The 2004 tsunami was about magnitude 9.2, which corresponds to a release of approximately 63 million times as much energy. (The scale is logarithmic - each increase of 1 magnitude corresponds to 31.6 times as much energy. 31.6^5.2=62,859,776.) So, an asteroid 63 million times the size of the one that hit Tunguska? That does seem high...

Who the hell wouldn't be worried whether or not it's going to work? Who are those 17%?

Extravagant spending is part of the point of it, actually. The analogy with buying an expensive car isn't applicable. He'd have to be buying it from himself, and building it himself too. It's about real wealth creation - building a car and getting paid for it instead of trying to find a job, and then keeping the car. Now, you can disagree that this is the best allocation of spending or even with the whole concept of stimulus spending (although that would be better argued in a different topic), but don't misrepresent the fundamental concept.

As others have said, the biggest hazard of electric shock to humans is overloading the nervous system, which can stop the heart and lungs among other effects. But that’s not the only hazard – a more straightforward one is simply burning. Where electricity meets resistance, it heats up everything in its path (that’s what an electric stove is), and since the body is not nearly as good a conductor as something like a copper wire, very high voltage passing through you is going to fry your insides along the route the current takes. I’m guessing it would also fry algae, so no, they’re not immune to electricity. That said, I still doubt you’d be able to make it work, for the reasons DrDNA mentions. It would also be very dangerous to try to get around those obstacles, so I discourage the attempt.

Accounting for 50% of variation is not the same thing as "changing your intelligence by 50%."

Objects that size hit the Earth at an average rate of about 1 per year. So, the answer is "zero tsunamis."

No, it really won't. You're vastly underestimating the kind of energy involved in a "devastating tsunami." By many orders of magnitude. Nuclear bombs cannot cause tsunamis. Especially not in the upper atmosphere. And frankly, the idea that every few decades one or another ocean's coastlines is swamped with tsunamis hundreds of feet tall, and nobody has realized it because we only just started living on the coasts (?) is, well, kind of ridiculous. You're welcome.

It wouldn't be "giving marriage to the religious." Nothing would be stopping anyone from saying they're "married," just the meaning of the word would have to be self-defined and not legally defined. For a religious person, it could mean "married in the eyes of God" or whatever, and for the rest of us it would just be a traditional formal pledge of love and commitment. Or whatever. While a "civil union" (or whatever) would be the legal agreement granting rights of shared property, power of attorney, child custody, etc. Similarly, there are several people I refer to as my friends, but there's no legal definition of "friend" anywhere. Yet somehow people manage to understand what I mean, and I don't feel particularly oppressed by the lack of official recognition. (On the other hand, if there was some religious group that managed to get "friend" legally defined according to their own standards which would come with legal priveleges, then that would greatly annoy me.)

A "global tax" is never ever ever going to happen, especially not one levied by the UN. Nor should it, nor is it necessary. The spacefaring nations have already managed to work together remarkably well, with things like the ISS and astronauts sharing rides on other nations’ vehicles. You're not going to see the level of investment you're asking for, though. It’s just not important enough in the short term*, and our ability to deal with NEOs will inevitably increase naturally, as space tech in general improves. *I know you think it’s the most important thing ever, but again, risk vs. reward. Tunguska sized impacts happen on average about once every thousand years or so, and when they do happen, they’re mostly harmless. Yes, harmless. The Tunguska event was a release of energy about equal to a midsize nuclear weapon. Enough to wipe out a city if it’s a direct hit, but we’re not talking about tsunami-causers, which are orders of magnitude rarer. And hitting a city is very unlikely. Most of the Earth is ocean, and most of the land is sparsely populated. Almost certainly, several have hit the Earth over the history of human civilization, and nobody noticed.

The Earth's core is solid, not plasma.

http://forgetomori.com/2009/ufos/worst-dressed-grays-list/ An amusing compilation of alleged alien abductee's descriptions of extraterrestrial fashion choices, together with totally coincidental similar depictions in popular culture.

That intelligence is at least partly inherited would be pointless to deny, as is the fact that it is not entirely inherited. Pretty much every study ever supports that very general statement, as does common sense. The reason there's no such agreement on the details is because "intelligence" itself is such a slippery concept, poorly defined and less well understood. Modelling it as some kind of substance that a mind can possess in greater or less quantities is tempting and has some uses, but ultimately is probably a poor representation for what is actually going on.

I'm thinking it would be more effective to actually spend it on some sort of preventative measure.

That's true, of course, but "one person" is an exaggeration. It's probably the most impressive team of economists ever assembled. Not to say that that makes you wrong - I'm not saying a "best team of people" can really predict the market, either. But that's precisely the problem. That particular strict contrast between government intervention and "market forces" seems like a false one, because in reality the big fluctuations we see day to day are not caused by consumer behavior (like long term trends are), but by the hurried predictions of an over-excitable mob in a room on Wall Street and a handful of financial institution executives, which is kind of a de facto centralization.

Usually we just call that "west."