Sisyphus

1) Where did you get such an idea? 2) What convinced you it was more accurate than... all of medical science?

It's mentioned offhandedly in this NYTimes article about echidnas that their brains are 50% neocortex, which presumably is a lot (human brains are 30% neocortex). They also call them "brainy," and say they're surprisingly intelligent. Wikipedia says "a high neocortex ratio is thought to correlate with a number of social variables such as group size and the complexity of social mating behaviors" (unreferenced). What significance does it have? How unusual is a ratio of 50%? What are the odds that echidnas secretly rule the world?

Did you read through this thread?

The thing is, there's a very good tool for objectively evaluating whether something actually works, which we call science. If it is subjected to this tool and is proved to work, the "alternative" gets dropped from "alternative medicine." And the only real reason for purposely avoiding scientific evaluation is if you already know or strongly suspect it doesn't work, and want to keep selling it anyway. So yeah, anything called "alternative medicine" is almost certainly just bullshit. Of course, I guess that depends on your definitions. Certainly some herbal remedies are better than placebos, and you might call that alternative medicine, but generally that's just because they contain active ingredients that are considered medicine. And something like "a healthy lifestyle" isn't really "medicine," per se, and might be "an alternative" to specifically medical treatments, but again, that's something that can be and is scientifically evaluated by "medical science." So, you know, whatever. And finally, there's the good old placebo effect. If I was a doctor, I would be happy to let my patients try anything they thought might work (without actually endorsing it), as long as it wasn't actually harmful or a replacement for real medicine. Why not? And hey, homeopathy, in sufficient quantities, can be a very effective treatment for dehydration.

I'm afraid I don't. Let's see: Alright. In other words, there is no ratio between the finite and the infinite. True enough. Thus, if space is infinite, then any finite portion (like the visible universe) is no fraction of the total. Is that a supposition or an assertion? I guess. The analogy you're making, if I understand you correctly, is finite is to infinite as infinitessimal is to finite. That makes sense in that neither composes any fraction of its counterpart, but it's not exactly the same thing. No ratio is no ratio. And after that, I think you lost me...

How about: http://en.wikipedia.org/wiki/Ultraviolet_catastrophe (One of my favorite physics terms/great band names ever.)

This might be the most obvious comment I've yet to make here, but: People like sex. Why are we doing away with it, again? What is this thread about?

The two main reasons, I should think, would be magnitude of output and consistency/controllability. The Hoover Dam has put out 2 gigawatts of clean, consistent energy for the last 70 years (at the cost of localized screwing with the river's ecosystem). That's a role that it solar would find extremely difficult to fulfill. Merged post follows: Consecutive posts merged There are lots of different types of tidal power, and I expect we'll be making a lot more use of it in the next few decades. I think what you're talking about are the ones make use of horizontal flow, like "underwater wind turbines." The flow is more consistent and predictable than wind and, because its water instead of air, a lot more energy can be extracted. I've read somewhere that New Zealand was looking into the technology for the strait between the north and south islands, as the current is strong and broad enough there that they could basically power the whole country, and expand as needed. The downsides being that the ocean environment is very harsh, and maintenance would likely be difficult. There are other designs, of course, making use of vertical motion. Like huge barges that extract energy from both rising and falling with the tides.

Wouldn't it still be limited by a need to transport nutrients to the top? Or maybe there's some kind of hydraulic circulation or something? Also, why would it evolve to be that tall? Just intense competition for sunlight?

Actually I think those statistics are per 100000. As in 6 homicides per 100000 people in NYC in 2007, for a total of 494. And of those, fewer than a hundred were cases where the victim didn't know the killer. In a city of 8.5 million. In Manhattan there were fewer homicides than there were episodes of Law and Order. So yeah, I'd hardly call it a Robocop-esque pseudo war zone.

Well, that's rather more strongly worded than I was going for. Still, though, there's no such thing as "the criminals," as if there were groups of comic book henchmen out there somewhere.

Methinks you've watched too many movies? Most cops killed in the line of duty in the U.S. die in traffic accidents. Also, your bloodlust and implied separation into "us" and "them" is very unnerving. You little [Godwin] you.

Guesses with varying degrees of certainty. The outer core is very probably nickel-iron, based on its density, seismic characteristics, and the fact that nickel-iron is very common in our solar system, but you couldn't say it's actually proven. I also don't know any of the details of the actual calculations they use to determine this.

Most of what we know about the core is via extensive analysis of seismic waves. We know for sure it's solid, how dense it is, how it moves, etc. AFAIK stuff like the actual composition, temperature, etc., are educated guesses based on the seismic data, as well.

A good comparison of the visibility of the arch would be with Earth's moon. The moon's diameter is about 1/100th its distance from us. It is quite large in the sky and clearly visible in the daytime. Assuming our dimensions, the width of the ring at its farthest point would be about 1/200th its distance from an observer. Obviously this particular point would be behind the sun and thus always invisible, but most of it would be clearly visible. A quarter away around the ring would be almost as wide as the moon is to us, and it wouldn't be just a circle, but a huge band across the sky, widening down to meet fully half the horizon. So yes, it would certainly be visible, day and night. If anything, the "archlight" would be inconveniently bright at night.

Surely the answer is never?

Yes, basically. Although instead of saying that it wants to return to its original position, I'd just say it is pulled downwards by gravity. The ball is also pulled downwards by gravity, but, less so, because it is less massive. A cubic meter of water has a lot more downwards force than a cubic meter of air, so there is a strong tendency to push the air up and out of the way, which makes a simulated upwards force on the air. Or anything else that is less dense the medium its in. Helium is less dense than air, so a helium balloon has positive buoyancy in air, etc.

No, it's not a tube. It's flat, like a fan belt. In the book it's described as like a circular loop of ribbon, an inch wide and 50 feet long, with a candle in the center (the candle being the sun). "Inner" as in facing towards the sun, as opposed to away from the sun. The atmosphere is prevented from escaping by thousand mile tall walls at the edges, pointing towards the sun. A "ceiling" is thus unnecessary. And yeah, it's a sci fi classic and a quick read, so give it a look.

I didn't want to mar my ceiling, so I have mine suspended on a short elastic from a helium balloon (for neutral net buoyancy).

No, it's not that. If that were the case, once you got it under water and were no longer moving, it would stay in place. Instead, it still wants to shoot upwards. The way I think about buoyancy is that the force comes from the weight of the water. By pushing it downwards, you are, by necessity, displacing that same volume of water and pushing it upwards. In other words, you're lifiting it. This is easier to see in a smaller container, where you can actually see the water level rise, than in the ocean, but it works the same way. Holding a ball full of air under water is equivalent to holding that same volume of water up in the air. (This isn't the only way to describe buoyancy, but I find it's the most intuitive.)

CaptainPanic, only the inner surface of the Ringworld is habitable. It isn't in orbit around the sun, but is spinning quite a bit faster - fast enough that the centrifugal effect experience by someone standing on the inner surface approximates Earth gravity. It's held in place purely by the tensile strength of the material, which obviously is enormous. The day and night cycle is accomplished with a smaller ring similarly spinning at about half the radius, this one composed of large solid sections connected by ridiculously strong tethers. There are large bodies of water interspersed throughout the ring (though not connected, and tiny relative to the size of the ring itself, as well as two huge oceans on opposite sides. And yes, the surface area would be huge, which is the point: 3 million times the surface area of the Earth. Anyway, I read that book many years ago, but I'm pretty sure I remember some of those questions addressed. (If not there, then in the first sequel, The Ringworld Engineers). Curvature would be completely indetectable at the surface, creating the illusion of an infinitely distant horizon. The atmosphere would become opaque at a distance when anything noticeable would happen. However, the ring would still be visible overhead, appearing as an arch (with the sun under it!). I'm pretty sure stars would be visible at "night," too, as they are in a solar ecclipse. The construction is left deliberately mysterious, although I think allusions are made to "a suspension bridge with no endpoints." Weather patterns are addressed, too, I'm sure, in the discussion about the "eye storm," although I don't remember the details. The radiation shield bit is also addressed, although I think in the second book. So too is the gravitational instability. I won't talk about it, though, cus they're actually kind of key plot points...

Is anyone else just baffled why so many people are apparently terrified of these people in prison anywhere nearby? I mean, wow. Talk about "the terrorists have won," if they've got us this timid. Do people think we've got Hannibal Lecter down there? Maybe Magneto? No. These are people who would be lost in the U.S., and, judging by the ideology they (allegedly) subscribe to, probably aren't even that bright. Run of the mill gang members pose more of a threat. Which, of course, is practically nil, since people don't escape from supermaximum security prisons in the first place.

Great Scott!

I.... can't tell whether either or both of you are joking...

Most cops never fire a gun at all, in fact. The exception being SWAT teams, cops specifically trained for the situations when they need to act like soldiers. I'm pretty sure they already employ RC robots in some cases, although it seems robots that are as aware, quick, agile, or adaptable as a human simply don't exist yet, and certainly not for lack of trying. Robots in war are being developed more and more (the most prominent example being flying drones), but AFAIK something that could take the the place of boots on the ground isn't yet on the horizon. I could be wrong, though.