A man overcomes 4 km in an hour of leisurely walking. Wind speed - 35-70 km / h, space rocket - 8 km / s. The Earth, revolving around the Sun, travels 30 km in just one second. A fast movement is one that we stop catching at close range. Example: flying bullets, shells. But what is the fastest thing in the world? The article will be the answer to this question.
How the speed of light was measured
People have always been interested in what is the fastest in the world. Many scientists tried to find out whether the light spreads instantly or with a delay, but the Danes O. Roemer succeeded for the first time. In 1676, an astronomer observed the motion of the satellite of Jupiter and noticed that he was periodically late. The fact that the distance between the Earth and this gas giant is changing was natural: at the time of each new observation, our planet was moving in orbit.
Another thing was curious - this distance increased by an amount equal to the diameter of the earth's orbit. It was at the time of the greatest distance between the two planets that the satellite came out of the shadows with a maximum delay. After comparing the facts, Roemer realized that the light wave does not propagate instantly. He divided the diameter of the Earth by the delay time of the satellite and calculated the speed of light.
How the speed of sound was measured
At the beginning of the XVII century, science did not yet know what was the fastest in the world. The Frenchman Mersenne tried to get an answer to this question. In 1630, a scientist, to find out the speed of sound, conducted an experiment with a shot. He measured the distance from the observer to the weapon and divided it by the time elapsed between the flash and the sound of the shot.
After 50 years, Isaac Newton calculated the speed of a sound wave. It turned out that his theoretical result and the result of the Mersenne experiment are very different. Only in 1808, the Frenchman Poisson came to the conclusion that the value obtained by Newton is true only for a constant air temperature, which is impossible to achieve under ordinary conditions.
In 1822, the experiments of a group of French scientists confirmed guesses. The conclusion was this: the speed of sound depends on temperature, the higher it is, the faster the sound wave propagates.
Sound or light - which is faster?
At zero air temperature, the speed of sound is 331 m / s. At 20 ° - 344 m / s. A sound wave propagates not only in air, but also in liquids, solids. It is known that the more a substance resists compression, the better it conducts sound. So, the speed of sound in water is 1484 m / s. Metals, for example, aluminum, steel, iron, conduct sound at a speed of 5000-6000 m / s, and sapphire - at a speed of 11400 m / s.
The value of the speed of light obtained by Roemer was slightly corrected, and more than once, because the methods of measurement and calculation changed over time. Light travels a distance of 150 million km in 8 minutes. Its speed is slightly less than 300 thousand km / s, but for the convenience of calculations it is customary to round off the value.
Today, science knows for sure: light is that which is the fastest in the world. In other words, these particles move faster than anyone.