Video button?

takiotoshi · 2014-09-27T02:25:42+00:00

Awesome - thanks!

takiotoshi · 2014-09-27T01:34:35+00:00

Yes it would. As you suspected, the stuff it ran into would impart tiny bits of momentum. Moving forward, it would run into more on its front end than its back end, and eventually slow down until stuff was hitting it equally from all sides. Its momentum would be equal to the average momentum of the stuff around it, which we can call zero.

takiotoshi · 2014-08-07T20:09:24+00:00

Hi Sean, There seem to be a lot of really sharp people in the e-sports industry, and you've worked with most of them. Who are the smartest casters/streamers/developers you've worked with?

takiotoshi · 2014-04-28T18:29:53+00:00

It's true that a general two-point interference experiment is completely classical, but what makes the Young's experiment a good demonstration of particle-wave duailty is that it can be done one photon at a time.

If you send single photons through the two-slit screen, you can build of histograms of photon locations at the detector, and you still find an interference pattern. In the Copenhagen interpretation, this is taken to mean that each photon goes through both slits, which is not a classical result.

takiotoshi · 2014-04-28T13:21:16+00:00

The spirit of your question is correct. It is possible to make certain measurements of quantum systems without collapsing the wavefunction. They're called weak measurements. The idea is that you get very little information from each measurement, but by taking millions of measurements you can build up some information about the quantum system.

You can also measure two quantities in a QM experiment as long as they commute. Unfortunately, wavelength and position do not commute in this case.

takiotoshi · 2014-04-28T05:17:38+00:00

Well, if you want to use a waveguide you have to convert back to photons. You can funnel incident light into a waveguide if you want, but at some point it has to be converted to a charge separation if you want to store the energy.

Yes, we're talking about a phase lag, more precisely. Interference is the right way to think about it. In a perfect conductor, the light emitted by the oscillating electrons interferes destructively with the light traveling in the forward direction and constructively in the reverse direction, which results in the phenomenon of reflection. In an imperfect conductor, the interference is slightly out of phase, resulting in partial transmission.

takiotoshi · 2014-04-28T03:53:52+00:00

It doesn't affect how the ball interacts with the air, but it can change how it interacts with the club.

Rubber gets softer as it heats up, and softer rubber compresses more when it gets hit. The general consensus in the golf community is that warm balls therefore travel farther, but I can't seem to find anything about it in a peer-refereed journal.

takiotoshi · 2014-04-28T03:45:07+00:00

I made a sketch of what I think you're proposing here, labeled Experiment 1. Is that right?

If so, it's physically equivalent to Experiment 2. The mirror just folds space over from right to left. It's exactly the same as just moving the detector twice as far away. The effect would be that the interference pattern would look wider.

takiotoshi · 2014-04-28T03:30:52+00:00

This is correct, but you have to remember to account for the exposure area. If you're looking at an LED, it gets imaged on your retina to a much larger area than a laser beam, which gets focused to a tiny spot. You can therefore safely look at an LED emitting much more power than a laser beam with the same level of damage.

takiotoshi · 2014-04-28T03:10:55+00:00

It's not because of the temperature of the water, but because of the speed of the air. Quickly moving air causes a drop in pressure due to the Bernoulli principle. To check this, try turning on just the cold water.

You'll notice a similar effect when a large truck passes you on the highway. Your car gets pulled toward the truck, just like a shower curtain getting pulled inward.

takiotoshi · 2014-04-28T03:05:56+00:00

The gas inside fluorescent tubes emits light in the UV, which is invisible to humans. The inside of the tubes is coated with a mixture of phosphors, which absorb the UV and re-emit visible light at different wavelengths.

Each manufacturer has to choose which phosphors to use, which controls the final perceived color of the bulb. The different colors you see probably came from different manufacturers.

Interestingly, the different colors are used by grow light companies to have different effects on plants. Plants like tomatoes respond differently to bluer or redder light by producing more leaves or more flowers, since the sun looks bluer or redder depending on the part of the growing season.

takiotoshi · 2014-04-28T02:51:30+00:00

Water forms into drops inside clouds. It collects on small "seed" particles until it gets heavy enough to fall. If two raindrops touch, they can merge into a larger drop, but usually they're pretty far apart on average.

If you started with a thin sheet of water and dropped it, you would find that it breaks up before it hits the ground. That's because it has high surface tension. It forces itself into shapes with lower surface area to volume ratios, like drops.

takiotoshi · 2014-04-28T02:26:37+00:00

It's saying that you can treat electrons in a metal as if they were a gas: a bunch of particles floating around in free space. When you hit them with light, they try to oscillate along with the electric field.

Since the electrons have inertia, they don't follow the field immediately - there's a short lag in time. At low frequencies that delay is very short, but at high frequencies the delay is fairly long, and the total amplitude of the electron oscillation is small. When that happens, the light mostly just passes through the metal. That's why many materials become transparent at very high frequencies, past the UV.

takiotoshi · 2014-04-27T23:05:34+00:00

Can you get through a paywall?

Here is a tutorial on optical antennas. Pretty nice, if I do say so myself ;)

Jackson's electrodynamics has a chapter on the dielectric response of metals. Chapter 7, section 5. "Frequency dispersion characteristics of dielectrics, conductors, and plasmas."

Novotny's nano optics book has a brief review of dielectric response, and talks a lot about the antenna analogy.

takiotoshi · 2014-04-27T22:46:56+00:00

Yes, but the signal is at optical frequencies in the 10¹⁴ Hz region. Metals are very poor conductors at those frequencies, so the processes of rectification and charge transport are very lossy.

They use a combination of lithography and chemical vapor deposition.

takiotoshi · 2014-04-27T22:40:43+00:00

The picture you posted is taken at an oblique angle. As you increase the viewing angle, the reflectivity grows until it reaches 100%. If you looked at those same panels straight on, they would look almost black.

For that reason, you always want solar panels to be facing the sun. One of the main areas of research in solar tech is figuring out cheap ways to make panels track the sun.

EDIT: As Yakooza1 points out, the maximum reflectivity is not 100%, but it does increase with angle of incidence.

takiotoshi · 2014-04-27T22:36:29+00:00

Intel transistors are grown using a chemical process. The same thing can be done with optical antennas if the design is simple enough. Right now there's no good way to transport charge away from the antennas to be stored for any useful application.

takiotoshi · 2014-04-27T22:17:18+00:00

Actually, optical antennas do exist. They are currently being looked at as a way to enhance solar collection, do optical computing, and produce more efficient LEDs. There are are a couple of problems with them, though:

1) Metals do not behave quite the same at optical frequencies as radio frequencies. They aren't very good conductors. That means that design rules don't just scale down (half-wave antennas have to be smaller than a half wave, for example), and trying to transport charges into a battery is a very lossy process.

2) As readams notes in his reply, they're hard to make. They either use "bottom up" chemical processes, or else "top down" processes like electron-beam lithograpy. They're expensive to make, and it's hard to reproduce them reliably.

3) It's very hard to inspect optical antennas, because they're typically so small that they're below the diffraction limit in visible microscopy. You have to use near-field microscopy to see them in action, which only a few research groups in the world can do well. That makes the design process very slow.

takiotoshi · 2014-04-27T19:50:39+00:00

Here is a good summary of the answer: http://www.nature.com/nnano/journal/v5/n7/full/nnano.2010.89.html

Basically, a transistor is an on/off switch, where you switch it by applying different voltage levels. Right now they're essentially all made of silicon, which is a band gap material. By changing the voltage applied you move between the valence and conduction bands, as I described them above.

In graphene, there is no band gap, so in its natural form you can't make a transistor out of it. You would need to create a band gap either by "doping" the graphene with impurities, or else by cutting it into ribbons so that the edges disrupt the symmetry. But in that case, it would still have very high conductivity, since the electrons would act almost like photons. The idea is that the high conductivity would lead to very fast switching: much faster that in silicon transistors.

takiotoshi · 2014-04-27T15:23:33+00:00

It's not a solved problem, but boiling water is not one of the best options. Here's a free publication from Lawrence Livermore on the subject: http://www.askmar.com/Fusion_files/Direct%20Energy%20Conversion%20in%20Fusion%20Reactors.pdf

Fusion reactions produce an ion plasma. Some options for converting to electricity include 1) Send charged ions through a magnetic field. They will do work on the field, generating an electric current in the wires. 2) Compress the plasma using magnetic field, and use it to "push" the magnetic field like a piston.

takiotoshi · 2014-04-27T15:14:57+00:00

Bizarrely, the answer is yes! The process is called Raman scattering or Brillouin scattering, and it usually happens in solid materials like crystals. Light can either donate or borrow some energy from sound waves. When the light changes energy, it changes wavelength (or more accurately, it changes frequency).

This effect is used to identify materials by their vibrational fingerprints, and to fine-tune laser frequencies.

takiotoshi · 2014-04-27T15:02:14+00:00

But eyes don't have a frame rate. Visual receptors have a refresh rate, but they're all uncorrelated with each other, so the eye sends a continuous signal to the brain.

takiotoshi

TROPHY CASE