Slashdot Mirror
Strange Bacteria Sustains Itself Without Sunlight
Hahnsoo writes "A colony of bacteria found 2.8 kilometers below the Earth's surface in a South African gold mine is able to sustain itself without energy from the Sun. While sub-surface colonies of microorganisms utilizing sulfur (mostly near deep sea hydrothermal vents) is not new, this particular colony is unusual. The colony does it by relying on radioactive uranium to split water into hydrogen gas. Thus, instead of solar energy and photosynthesis, this species relies on radioactive materials and sulfur/hydrogen to facilitate its energy needs. There is some speculation about life on other planets in the article as well."
"What is the point of having an electric car if you're just going to charge it by burning coal and oil?"
Electric motors are much more efficient.
Electricity can come from non-polluting sources.
The cost of electricity hasn't risen 300% in six years.
Pollution from a few sources is more easily managed and disperses less than from millions of ground level sources.
Electric cars are simpler mechanically, more reliable and easier to repair.
Electric cars accelerate faster and can use regenerative braking.
Existing range limitations can be overcome with improved battery chemistry.
see www.whokilledtheelectriccar.com to see why we're not driving them and why all the EV1's were destroyed.
Offtopic but you did ask.
That's partly true. The burning covering provided the soot that was able to glow and make the flames visible. Hydrogen flames are almost invisible.
However, urban legends about the extreme flammability of the doping notwithstanding, there is NO WAY a vessel the size of the Titanic could be vaporized in 30 seconds, throwing a mushroom cloud hundreds of feet into the air, unless the reaction was driven mainly by the burning hydrogen gas. The gas did dissipate quickly; it just happened to be burning as it did.
Actually, that's not entirely correct. No star we know produces elements heavier than iron and nickel, which aren't very radioactive. In fact, they're the most stable nuclei we know.
The thing is, anything lower than iron and nickel tends to release energy when fused into something heavier. Anything heavier than that needs to absorb energy to fuse into something even heavier, and conversely releases some energy when split.
So eventually the reaction stops at iron and nickel. Given intense photon bombardment in the star, most nickel actually disintegrates right back into smaller nuclei, not fuse further into heavier stuff. Iron pretty doesn't do anything whatsoever, and just stays iron.
The thing there is that as you move upwards, the energy and temperature requirements tend to be insane. For example for the next step up from fusing hydrogen into helium, it takes a red giant and temperatures of about 100 _million_ Kelvin to even fuse helium into carbon before blowing itself up.
And most stars either (A) stop short of even that and become a red dwarf, or (B) blow themselves up within seconds when they start fusing helium, because that's a very unstable reaction, whose rate increases with temperature, and temperature increases with fusion rate.
But at any rate, even if you had a star massive enough, you wouldn't get many nuclei past iron, or you wouldn't get them out of the star. By the moment a star got massive and hot enough to start fusing iron into something heavier, it would just rapidly lose heat in that reaction. It just can't explode that way, so at most you'd get a black hole in the end of it all.
So since you mention stars exploding... well, that's actually where the heavier elements come from. Supernovae don't just spread those heavier metals, they _create_ them. The iron, carbon, helium and whatever else was created will be smashed with tremendous amounts of energy and at insane temperatures, and a lot of it will fuse into heavier stuff. And since the star is already blowing up, they'll get spread all over the place.
A polar bear is a cartesian bear after a coordinate transform.
And to further answer the GP's question, there's been plenty of time since the Big Bang for this process to happen (several times). Large stars burn through their fuel much faster than well-behaved dwarf stars like our sun. I believe that a supergiant star can complete its lifecycle in about 15 million years. That means that if current estimates on the age of the universe are correct, that it could have happened over 900 times by now, assuming a perfect linear succession of supergiant stars. The real estimate is probably much closer to a couple hundred, but there has certainly plenty of time for all the heavy elements in our planet (and the rest of the solar system) to have formed in the hearts of stars since the Big Bang.
As Carl Sagan said, "We are all made of starstuff.".
End of lesson. You may press the button.