Shining meat, can I get my mouth?

"The beautiful day is about to end again. Tomorrow on weekends, I have to eat some good on the weekend." As I sorted out the desktop, I calculated in my heart to wait for something to buy. Decided, tonight, I will eat the famous food from Leshan, Sichuan -Sweet Duck!

After get off work, go to the market, buy sweet skin ducks, go home in one go. Just when I opened the box, strange things happened. How did this duck sparkle? Is it too hungry and I can't see it clearly?

Duck meat presents colorful metallic luster at different angles (picture source: author shooting)

After careful observation, I found that the metallic luster only occurred in a place where the muscles were solid. This phenomenon did not observe the bone, white fat layer and epidermis. Therefore, after reasonable speculation, this should be related to the interaction between light and muscles. What about the details, and listen to me slowly.

1. The structure of the muscle

Muscle microstructure schematic diagram (translated by the author of the author, see the source of the picture)

Taking skeletal muscle as an example, skeletal muscle fiber is muscle cells, with slender shape and multi -core cells. Skeletal muscles are composed of muscle fiber bundles, muscle fiber beams are composed of muscle cells, muscle cells contain multiple muscle fibers, and muscle fibers can be divided into several muscle sections. In the fine structure of the muscles, it is divided into coarse and thin muscle shreds.

Looking at the word "muscle" full of screens, don't you know this word? It doesn't matter, just need to know that the muscle structure is complicated, and it actually looks very simple. It is a piece of rules one by one, like a wire and cable. After cutting the meat horizontally, the muscle section is composed of a small cut surface. When the light is cooked and the oily muscle is cut, the reflection of light is actually done by small cut surface.

So what does this have to do with color reflection? Please continue to look down.

Second, the interference of light waves and grating scattered

When the rain drops falling on the calm lake, the lake surface became active, and the water waves on it were painting their circles lonely, but it seemed to be interfered with each other.

The raindrops fall on the lake (picture source: Veer gallery)

A kind of electromagnetic wave, it spreads in vacuum, is a fixed value. Usually it is represented by letters C. The approximate value is 300,000 kilometers per second. What is even more amazing is that the speed of light in real vacuum is not related to the motion status of the inertial reference system, nor is it related to the color of light, that is, the frequency of light. Because in the air around us, the refractive index is not changed much, so the relationship between "frequency and wavelength is equal to the speed of light" can be known that in life, we can also think that the color of the light in the air is related to the wavelength.

The transmission of a single light wave source and the dissemination of the double -point light wave source (picture source: author provided by the author)

As shown in the figure above, when there is only one point light wave source in the space, the spread of light is like a drop of water falling on the water surface, spreading around, and gradually weakening as the waves far away from the light source. This is the result of conservation of energy, because with the expansion of the circle, energy is certain, which will inevitably lead to gradually weakening the waves increase with the increase. Imagine that we lit a candle, the farther the fire will become, the darker.

When there are two point light sources in the space in the space, the spread of the waves is no longer uniform, but the directionality appears. In some directions, the spread is strong, and some directions are weaker or even zero. This is also a manifestation of energy conservation -in some directions, there must be a weak direction of spreading and concentrating energy.

Is it even more amazing about the horizontal section of the muscle? That's right, this is what happened!

Third, grating and color scattered effect

The dissemination behavior of red and blue light in the "muscle model" (picture source: author provided by the author)

Mathematical modeling and physical modeling of the muscle structure, each muscle fiber bundle is regarded as a wave source connected, and the spacing of light sources is far less than the wavelength. The gap separated by the muscle membrane can be regarded as a broken source of continuous wave source. According to the micro -structure of the muscle shown in FIG. 7, the diameter of the muscle fiber section is about 50 μm and the interval is about 10 μm. From this data, we carried out the simulation after the light wave reflected on the muscles, and found that the magical phenomenon appeared!

Scanning electron microscopy images of cooked muscles under normal pressing (picture source: reference [2])

First of all, regardless of the color of light, their communication has obvious direction. Secondly, according to "red, yellow, yellow, green, blue, blue and purple", the light waves of red colors are long and the blue wavelel length of the blue color. In the process, except for the symmetrical lines perpendicular to the muscle surface, they are the same direction, red light, which The folding angle is less than the blue purple light. This is exactly the opposite of glass refractive behavior.

And this structure is like a grid (zhà) column, and this structure is also called "grid (shān)" by the image. As for why reading the grating (shān) is another story.

1200 anti -light racks per millimeter (picture source: author shooting)

Because different colors of light shows different communication angles except the center, the grating structure has the effect of separating the light according to the color of the color (accurate as the wavelength and frequency), so the grating of our grating has scattered ability. One of its most important applications is a spectrometer.

Optical fiber spectrometer structure (picture source: author shooting)

Grav Sanda renderings (Picture Source: Author provided)

Is there a grating in life that allows us to see the rainbow -colored light? Of course, that is the CD.

CD -ROM and hexagonal wrenches (pay attention to shadow and color sorting) and the micro -structures of the CD -ROM electronic microcontrol structure (picture source: authors) The microstructure of the disc is also a fence of a lane. The point above is the burned information. In the figure, we can see that the shadow is on the left side, indicating that the sun is on the top right. The red light on the left is on the right side, indicating that the red light corner is larger than the blue light, and it also meets our simulation results.

Therefore, if you also want to see the glittering meat, you can try to observe it, because the cross section of the muscle is basically flat, and you will have the color dispersing effect of the grating. Through the above simulation experiments, I believe that we have solved the doubts at the beginning. Faced with this shiny meat, you don't need to be tangled to eat, taste it!

Produced: Popular Science China

Author: Tang Hongyang (Institute of Optoelectronics Technology, Chinese Academy of Sciences)

Producer: China Science Popularization Expo

references:

[1] Zhong Xihua. (2012). Modern optical foundation. Peking University Press.

[2] Wang Zhijiang, & Jiang Aimin. (2015). The impact of ultra -high -pressure treatment on the micro -structured chicken in cooked chicken.

The China Science Popularization Expo is the Science Popular Science Platform of the Chinese Academy of Sciences. It is sponsored by the Computer Network Information Center of the Chinese Academy of Sciences. Relying on the high -end scientific resources of the Chinese Academy of Sciences, it is committed to spreading cutting -edge scientific knowledge and providing fun science and education services.

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