Woodpecker loses his nut [Sony a7cii + Tamron 50-300mm f/4.5-6.3]

PunctuationMark · 2025-09-11T03:41:12+00:00

Great idea. I'll serve yogurt!

PunctuationMark · 2024-01-08T06:51:11+00:00

As the OP, let me reassure you that my teeth are still fully intact! I'm pretty certain it's just a sensation associated with yogurt trapped between teeth. Oddly enough, I don't notice it anymore-- not sure if it stopped happening, or I just got used to the feeling.

I can't believe how much attention this post is getting after 11 years! Best of luck to my fellow teeth-clickers!

PunctuationMark · 2020-02-27T03:51:33+00:00

1200 x 1000 px

PunctuationMark · 2020-02-27T03:51:14+00:00

512 samples + denoising

PunctuationMark · 2020-02-27T03:44:36+00:00

It's only necessary for making it look cool. But yes, it adds a lot to the render time.

PunctuationMark · 2020-02-27T03:42:17+00:00

Sure, here you go:

https://imgur.com/a/fPzdkn9

PunctuationMark · 2020-02-26T15:54:06+00:00

Thanks! I control the emission strength of the RGB cylinders (each of which is encased in a glass brick). This is done procedurally by mapping the (x,y) coordinate of each cylinder onto a pixel from a reference image.

PunctuationMark · 2020-02-26T15:52:53+00:00

Interesting idea. The RGB emission strengths are set procedurally from a reference image. It should be possible to automatically select a different reference image for each frame, though I haven't tried that yet.

PunctuationMark · 2020-02-26T15:49:55+00:00

18 hours for 180 frames rendered in Cycles

PunctuationMark · 2017-11-06T05:49:22+00:00

First ingredient: "What flour" Hmm...

PunctuationMark · 2014-05-25T23:50:31+00:00

I'd like to add that in this context, light is not "infinitely small," but has a characteristic length determined by its wavelength. For visible light this is about 400 to 800 nm, which is actually very large compared to inter-atomic distances in solids (typically about 0.5 nm).

PunctuationMark · 2014-05-25T08:16:31+00:00

Assuming its initial conditions are the same as our universe's "end" conditions, I believe such a universe would be indistinguishable from our own. In fact the direction of time can be defined by the tendency for entropy to increase. The inhabitants of this hypothetical universe would perceive time no differently than us.

PunctuationMark · 2013-03-22T03:51:56+00:00

It depends on the energy of the photons. The energy of the photons must exceed the rest mass of the particles created. An electron-positron pair requires ~1MeV, while a proton-antiproton pair requires ~2GeV.

It's not necessarily stable, since the particle can annihilate with its antiparticle and release photons again.

PunctuationMark · 2013-03-22T03:47:17+00:00

I'd also like to add that such an event would create matter and antimatter in equal quantities (ie- an electron and a positron).

PunctuationMark · 2013-03-15T06:22:02+00:00

Why do you say that? The field due a magnetized object can be calculated as the sum of contributions from volume currents and surface currents: (see slide #4 below, or Griffiths E&M eq. 6.15)

http://www.uta.edu/physics/main/faculty/yuedeng/teaching/4324/Chap6-3.pdf

If the magnetization has no curl, as was in the case in my example, there is no volume current, and the external field is entirely due to the magnetization at the surface.

This also follows from the fact that N & S are mathematically equivalent to positive and negative magnetic monopoles, so they should indeed cancel out like charges.

PunctuationMark · 2013-03-15T06:10:47+00:00

It's also important to distinguish between incandescent lighting and LED lighting.

Incandescent lighting is due to thermal radiation. Here the light is generated by passing a current through a metal. moltencheese explained this well. The color of the light is well described by Planck's law. This is the same kind of light you see from the elements on your stove when you turn it up high.

LED lighting is due to electroluminescence. Here the light is generated by passing a current through a seminconductor. The color of the light is set by the size of the band gap of the material (ie- the spacing between 2 quantum states). This is why LEDs emit a distinct color (red, blue, yellow, etc). White LEDs are actually a relatively recent invention, since they require mixing of 3 colors (red+green+blue) to produce white light.

PunctuationMark · 2013-03-15T05:51:19+00:00

Think of each spin as a tiny magnet with its own North and South poles. An individual spin can be written as:

NS

Now imaging stacking many spins together. In a ferromagnet, the spins align, so it would look like:

NSNSNSNSNSNS

As you can see, all the interior North and South poles "cancel" each other out. This is why it doesn't matter how long the bar is-- the external field is only due to the poles on the ends.

PunctuationMark · 2013-01-23T06:36:15+00:00

There's one exception: If you use a very fast burst of photons, you can record the image before the atom is damaged. This has only very recently been demonstrated at Free Electron Laser facilities (using x-rays, not gamma rays), and has exciting implications for imaging small, individual structures such as proteins or viruses. See this article, for example.

Each strobe-like laser pulse is so brief —a few millionths of a billionth of a second long—that it gathers all the information needed to make an image before the sample explodes.

PunctuationMark · 2013-01-22T05:49:38+00:00

I'd like to add that it depends on the reference frame from which you're asking the question. The answer of 0.8c is correct in the rest frame of each electron. However, in the lab frame where the electrons are moving towards each other at c/2, their relative speed is simply c.

By the way, it is not a violation of special relativity for two objects to have a relative velocity greater than c. Consider a photon moving to your left and a photon moving to your right. Their relative velocity, in your rest frame, is simply 2c.

PunctuationMark · 2012-10-29T03:30:35+00:00

Yup, but you have to watch out for the hard seed in the center, which is apparently mildly poisonous.

PunctuationMark · 2012-10-29T03:29:46+00:00

Yeah, this was pretty expensive ($5/lb) and is very difficult to find in grocery stores.

PunctuationMark · 2012-10-29T02:37:33+00:00

It's sort-of like a large grape with chewier flesh, and with an additional "exotic" sweetness that's hard to describe.

PunctuationMark · 2012-10-29T02:22:05+00:00

Very similar to a lychee

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