It is said that cats have "nine lives", and given that cats probably came to China around the Tang Dynasty, the idea that cats have nine lives has not been found in ancient Chinese texts or novels, (probably from a kind of witchcraft from abroad) A book written by an English author William Baldwin in 1584 called "Beware of Cats" contains the phrase: A witch can occupy her cat's body 9 times, that is, cats can have 9 lives. Of course, this is not to say that it is really dead after it dies nine times, but that the cat is very capable of surviving and is not easy to die.
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For many well-known physicists, cats are friends at work, partners when they relax, and even tools in experiments, and these physicists always throw cats from windows downstairs with curiosity: why they always land on all fours when they land.
From the physicist Maxwell to the mathematician Stokes, they are all "cat throwing masters" in the academic world, Maxwell explained, my research purpose is to find out how fast the cat can turn over, and the research method is only to let the cat jump off the two-foot table or bed, but in this case the cat is still on the ground.
Stokes also tried to see something interesting and unusual in the cat's body flipping problem. The study of the "cat problem" is inseparable from high-speed cameras. Back in 1894, French scientist Étienne-Jules Marey published a photo of a cat falling with a high-speed camera on Nature, showing that the cat had completed the turnover movement in the first 1/8 second of the fall.
If the cat is thrown from the sky on all fours, in the process of falling, the first head and neck are twisted, then the forelimbs and torso are also twisted, and finally the hind limbs are also twisted.
Therefore, when the moment falls to the ground, it is first landed on all fours. Its series of reflex activity processes and mechanisms are the same as the upside-down reflexes of animals after being pushed down or flipped.
They gave this skill a name: the flip reflex. Because its reflex nerves are strong, it can quickly adjust the body in a limited time in the high altitude, maintain balance and land on all four feet, which is incomparable to many higher creatures.
In 1969, two researchers, Kane and Scher, built the Kane-Scher model, which modeled the cat as a pair of connected cylinders capable of changing the opposite direction, representing the upper and lower bodies of the cat, respectively, and the two parts rotated with zero angular momentum.
For the average cat, as long as the height of 30cm can be completed to complete the flip, the process is as follows:
Bend the body so that the front and back of the body rotate on different axes.
Flex the forelimbs to reduce the moment of inertia (MOI) of the front half of the body while stretching the hind limbs to increase the moment of inertia of the lower body. This allows the front half to rotate at a greater angle (90°) and the back half to rotate at a smaller angle (10°).
Stretch the forelimbs and flex the hindlimbs so that the rear body rotates at a greater angle, while the front half rotates in reverse at a smaller angle.
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Coincidentally, a doctor in Australia did not believe in the legend that cats had nine lives, so he found one hundred and fifty different cats and did a cruel experiment, he threw cats of different sizes from different floors, and examined the different degrees of damage to their bodies.
About one-tenth of cats died on the spot, and the Doctor believed that if it was at the right height, the cat's survival ability was very high, the degree of injury was very small, and if the height of the third to sixth floors was smaller, and if the floor was too short, they would be hurt to a certain extent because they could not adjust the body perfectly.
If the floor is too high, the cat's bones cannot withstand the acceleration of gravity, which will cause greater damage.
Therefore, it can be seen from this experiment that cats do not actually have nine lives, and the legend of the nine-life cat is naturally self-defeating.
Legend has it that cats are tigers' teachers, whether domestic or feral cats, purr and purr after injury, which is one of the ways for cats to heal themselves; the reason why people call cats have 9 lives is inextricably linked to cats snoring when they rest. Scientific studies have shown that this purring, which comes from the larynx, helps them treat bone and organ damage. And human experiments have shown that exposing humans to sound waves at frequencies similar to cats' purring can also help improve human bone quality.
Tips: Please do not throw the cat from a high place at will, this is extremely irresponsible behavior.
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"Schrödinger's Cat" is the name of an ideal experiment proposed by the Austrian physicist Schrödinger in 1935, which describes the truth of quantum mechanics: certain properties of particles cannot be determined until measured external forces force them to choose.
The whole experiment was carried out like this: a cat in a box, and a small amount of radioactive material. Within an hour, there is about a 50% chance that the radioactive material will decay and release poison gas to kill the cat, and the remaining 50% probability is that the radioactive material will not decay and the cat will survive.
The cat about Schrödinger has led many scientists to have more reverie. When we don't observe the world, is everything in an uncertain superposition? If the cat were replaced by a human, he would never feel that he had been in a "dead/alive" superposition.
The difference between humans and cats is that people observe themselves, that is, people are "conscious" animals. So the more bizarre question arises: Are physical phenomena related to "consciousness"?
Physicists increasingly feel that "Schrödinger's cat" can exist in principle, but the current technology is not mature enough. At present, the technical conditions are still far from being far behind, and there is no difference between "technically impossible" and "impossible in principle".
For 2,000 years, we have believed that the world is as Plato described in the Republic: the same thing cannot exist in opposite states at the same time, nor can it be opposite at the same time. But now that phrase is less absolute. Schrödinger's cat grows up day by day, and one day the universe will show its more bizarre side.
References: Yan Xiangning, genius physics cat