Can everyone be below average? Infinite expected value and the St. Petersburg Paradox.

Keylynn · 9 months

The Cleveland Museum of Art is pretty great, and it's free admission.

boss1000 · 9 months

From a biologist's perspective, this answer is useless, but it's an interesting application of a really cool part of information theory.

Suppose I give you a list of random numbers, and ask you to sort them. It's possible to put a theoretical lower bound on the amount of energy you're burning by sorting them.

Start by measuring the change in entropy. The entropy of n random numbers is -Kb * ln(1/(# states)), where Kb is the Boltzmann constant = 1.38*10^-23 J/K, and the number of states = n!.

The entropy of n sorted numbers is -Kb * ln(1), since there is only one sorted state. ln(1) is zero, so the change in entropy by sorting the numbers is Kb * ln(1/n!). This is a negative number, since ln(x) < 0 if x < 1.

According to the Second Law of Thermodynamics, the total entropy of the universe must increase - that means, if the entropy of the part of your brain that stores these numbers decreases, the entropy somewhere else has to increase by at least the same amount!

So we know that your brain has to heat up at least enough to increase its thermal entropy by Kb * ln (1/n!). The thermal entropy change of a system is equal to the heat dissipated * the temperature. So we multiply our entropy by room temperature (around 300K), and after plugging some numbers into our calculator, we derive that the total energy dissipated by sorting 100 numbers, whether in our brain, a computer, or anywhere else, must be at least 1.510^-18 joules, or 310^-19 thermal calories, or 3*10^-24 nutritional calories.

tmsgirl · 1 year

This isn't like a "magnetic bracelet" - the magnetic fields generate eddy currents in the brain and materially affect the neurons. Regardless of whether or not it cures cancer, it certainly has an effect.

thethirdmoose · 1 year

It would still have the light traveling in it. There is a device called an optical cavity, or optical resonator, (http://en.wikipedia.org/wiki/Optical_cavity) that operates on this principle - it is used in lasers, for example, and has two parallel mirrors, each very highly reflective and very slightly transmissive. So by shining a light at one of the mirrors, you build up really high optical power inside the cavity, since if the cavity length is a multiple of the wavelength of the light, you build up really high optical power (lots of photons). If you have a gain medium, like in a laser, you get lots of stimulated emission, which means a whole lot more photons, all in phase. Now, if you remove one of the mirrors, you get a huge burst of light.

quantum_foam · 1 year

I did this by taking a piece of glass and holding it over a candle to get a nice thick layer of black soot on it, then holding two x-acto knife blades parallel to each other and scraping two nice thin lines right next to each other in the soot.

uvasfinest · 1 year

He got there faster when he was driving calmly.

carolinafever · 1 year

Aluminum deforms really easily, leaving everyone I know with a macbook with the misaligned screen problem, where the top half and bottom half are out of alignment, and some people with worse problems, like ethernet ports that don't work because the aluminum has deformed around them. Plastic is a much better material because it doesn't deform - if it's put under too much stress, it cracks, which believe it or not is better than permanently bending.

carolinafever · 1 year

incredible chassis

Aluminum is probably the worst material for a laptop chassis. It's possible that there are worse materials, like lead, or maybe cardboard, but I'm pretty sure cardboard is more impact resistant.

SureillBuildThat · 1 year

For a cool demonstration of this, check http://www.youtube.com/watch?v=cey-JBeHrww

EtaoinGuitardlu · 1 year

Current is the flow of charge.

Initially, your ground has some potential (say 0V), your - terminal has some other potential (say 5V), and your + terminal has a third potential (14 V).

What happens when you connect your - terminal to ground? The charges in the battery see a path to a lower potential - so they take that path. As this happens, the potential on the battery decreases. So there's a very short period where the charges move (in this case the electrons move from the ground to the battery), but after they're done moving, the ground and the - terminal of the battery are at the same potential - so there's no reason for the electrons to move, so there's no current.

A battery, on the other hand, is a charge pump. This means that it maintains a potential across the terminals - so if you put a wire between the terminals, as electrons move from - to +, the battery pushes more electrons down to -, using chemical energy.

JavaLSU · 1 year

Pound is a unit of weight/force (see: pounds/square inch compares to newtons/square meter), so foot-pounds compares with joules, and joules wins. But we also have things like BTU and calorie for energy.

cmortell · 1 year

They probably tell you to fuck off because there's no such thing as a non-specific immune response?

perceived_pattern · 1 year

http://ngrams.googlelabs.com/graph?content=fuck,+suck&year_start=1701&year_end=2008&corpus=0&smoothing=3 explains that phenomenon pretty well. old s's were written like f's.

raket · 1 year

"Point of view" is one of those cool phrases that gets pluralized in the middle, like this: "This is one of my favorite points of view".

disposablehappyslap · 1 year

Live well. It is the greatest revenge.

Alterego21213 · 1 year

Actually, you're going to die whether or not you develop AIDS.

thethirdmoose · 1 year

Is anyone else reading this entire thread in a thick canadian accent?

SpeakMouthWords · 1 year

RobotRollCall's answer is partially correct, but there's more. Our eyes measure luminous flux, which is the intensity of the light times the angle over which it falls. If a source of light is farther away, you have 1/r² photons hitting 1/r² pigment molecules on your retina, so it cancels out and looks "as bright". This doesn't work for stars because they are basically point particles, since the width of the star is such a small fraction of the distance from you.

tg989 · 1 year

I hear the Union won. No word on when troops will leave the South, though.

thethirdmoose · 1 year

We were also evolutionary designed to run around the savanna clubbing gazelles to death.

I'll stick with my supermarket, thanks very much.

alias08 · 1 year

It happened to me with the fourier series representation of floor(x), though it's still an awesome way to get the frequency space representation of a function.

fosskers · 1 year

Entropy - basically, there are way more tangled states than nicely arranged states. Since it doesn't take a lot of energy to tangle cords, jostling puts them into a random state, which is more likely to be tangled than untangled.

blagobung · 1 year

Cellar door.

thethirdmoose

TROPHY CASE

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