The z-axis is arbitrary; you just pick some direction and call it the z direction.

The "nucleus with balls spinning around it" is a significantly oversimplified statement of the true quantum weirdness that goes on in atoms.
See here and responses.

At atomic scales electrons cannot be thought of as points; instead they are smeared out probability distributions. They don't exist at any given point, there's a chance for a given electron to be found throughout a whole region of space, and the probability of finding it at any given point is given by a probability distribution. These probability distributions are called wave functions, and given an electron's wave function you can calculate the likelihood of getting different results when you take a measurement of the electron. It is a strange aspect of quantum mechanics that you can't calculate exactly what you will measure, you can only establish the probabilities of each possible outcome.

Another aspect of quantum mechanics is that if you measure, say, the energy of an electron in an atom, you can only get one of a certain set of discrete values, and never any energy in between those values. The energy of the electron is quantized. In general, if you measure an electron's energy you have a certain probability to get a result corresponding to the first energy level, a probability to find it in the second energy level, and so on. This is also the case for some other things you can measure, like angular momentum.

However, there are certain wave functions that correspond to exactly one value of energy; that is, if you have an electron with this wave function, you are guaranteed to get a certain energy value when you measure it. In fact, there is a special set of wave functions with the following three properties:

• They each have a definite energy level.
• They each have a definite total angular momentum around the nucleus.
• They each have a definite angular momentum around the z axis.

These wave functions are the atomic orbitals that are so important in chemistry. If you calculate the shapes of the wave functions that satisfy these properties, you get the shapes shown on the Wikipedia page. They are listed in a table indexed by the variables n, l, and m. n corresponds to the energy level, l corresponds to the total angular momentum, and m corresponds to the angular momentum around the z axis. For example, you can see that orbitals with high m (angular momentum around the z axis), like the ones on the very right of the Wikipedia table, are sort of flattened out by the centrifugal force from spinning fast around a vertical axis.

Whenever I see things like this I can't help but wonder if people aren't succumbing to the common assertion that things (scientific literacy, societal values, quality of education, etc.) used to be good, but things started going down hill this generation. Without some kind of supporting evidence my default position is to be very skeptical of this kind of assertion. What evidence shows that scientific literacy is going downhill?

Human heads cover quite a small percentage of the earth's surface; it would be rather remarkable if the balloon hit a person.

Anyway, pretty neat. I thought at first they were talking about a rocket, which I thought must cost much more than $150 to get 20 miles up. But I guess a balloon gets you much higher for much cheaper. Not as cool as a rocket though. I think really big amateur rocket launches go about 10 miles up? There are some impressive videos on youtube.

If it proved predictive, yes. If not, no.

No, that's not the point. Of course if your standards for statistical significance are low enough you will find all sorts of nonsense "correlations." That is not the point. The point is that while there is a very strong correlation between the income of Massachusetts pastors and the price of rum, the pastors are neither financing the rum trade nor profiting off it.

A robot that notices and picks up coins when they are dropped is not beyond our capabilities. The important point, I feel, is that at one point (when you were very young) you couldn't have performed any of those steps, but now you can. It's the creation of a robot with this kind of ability to learn and grow that is beyond our capabilities.

Then the title should have been "Bacteria Used to Make Toxic Metals Inert."

I voted for world peace, and this was my reaction too. Perhaps it just says that /. readers are cynical geeks; I wonder what you'd get from polling a different population.

if the human race lasts long enough. I'd rank them like this in order of increasing likelihood of impossibility:

• World peace: this just requires (a) nice people or (b) a powerful enough superstate, which should happen eventually. If this hasn't happened within 1,000 years it will be because we destroyed ourselves; technology will be too powerful for war. I think world peace is much more likely than an apocalypse, though
• Human level AI: obviously possible through brute-force simulation of a brain, so this must happen eventually. Will probably happen within 1,000-10,000 years.
• Immortality: will probably happen eventually through the advance of medical science, say within 10,000 years.
• Aliens: surely they exist somewhere in the universe, but the fact that there's no evidence for them suggests that the closest (intelligent) ones are very far away. I estimate 10,000,000 to 100,000,000 million years to first contact. If there is nontechnological life in the galaxy, perhaps only 100,000 to 1,000,000 years till we find some.
• FTL: a good chance that this is impossible in principle, but there's some real research into warp drives and physics is incomplete, so the door is still open. Say within 100,000 years if it's possible.
• Time travel: very likely impossible. Nature seems to work very hard to prevent any scheme by which time travel might succeed.

Pretty sure no one's going to stop you from taking a glass jar onto a plane. What are they going to do, confiscate glass picture frames in people's carry-ons? Heaven forbid that some pickle juice should make it on, though.