Enrique C

Not a new question I think but WHY?? I understand positive and negative, maybe even a ground wire, maybe more if you have several different voltages going into one wire... but why so many shapes? There's 4-pin round connectors, inline connectors, inline with a notch or a triangular side, square connectors, square with D-shaped side, square with a notch, plus round OR flat pins, or combinations of the two, or differently angled flat pins.... WHHYYY?

There are 10^23 visible stars; maybe many more, and ours has on e inhabited planet, and one more planet and moon that might be close to it. We've found small rocky planets at other stars. It seems almost inevitable that there is life elsewhere. We went from riding horses and using candles to putting telescopes in space, exploring Mars, building particle accelerators, nuclear reactors and neutrino detectors... all in less than 200 years. Yet humans have been around for a good fraction of a million years, the planet has been 'waiting' for 4 billion years, the universe is 14 billion years old. Who knows where we'll be in a million more years of technology, or a billion.

Yet we aim our radiotelescopes up and hear nothing. Where is everyone else? Can we possibly be the first ones to discover even radio communications? Do they all self-destruct or die from sudden disease? Is there a limit to technology? What's up? Discuss.

You have an airplane sitting on a moving runway (not fixed). The runway is like a treadmill, and it matches the speed of the plane but in the opposite direction. Can the airplane take off or not? Note that this is a tricky question.

Which do you think would win a drag race: a new Mustang or a Subaru Forester XT SUV? Why? Use sources.

Context: postulates of quantum mechanics, wavefunctions.

Background: Engineering graduate student (Calc3, DiffEq, PDE).

EELS of single-walled carbon nanotubes has been done by several groups but nobody has studied spectroscopy of a nanotube carrying a current. If I do momentum-resolved EELS on a nanotube while I apply a current across it, look at the sigma-to-pi peak and compare the parallel and anti-parallel DOS, will I be able to see the effect of the current?