The speed of light is 299,792,458 m/s, which is about 3x65,438+00 m/s, which is about 300,000 kilometers per second. The speed of light refers to the propagation speed of light waves or electromagnetic waves in vacuum or medium. The mass of an object is also related to the speed at which it moves. The mass of an object will increase with the increase of speed. When the speed of an object approaches the speed of light, its dynamic mass tends to infinity, so it is impossible for an object with non-zero mass to reach the speed of light. The speed of light in vacuum is the maximum speed of natural objects found at present.

Research methods:

1, astronomical method

1676, Danish astronomer O.C. Romer used the change of the eclipse time of Jupiter satellite to prove that the propagation speed of light is limited. 1727, British astronomer J. Bradley estimated the speed of light as c = 303,000 km/s by using the phenomenon of stellar aberration.

2. Bradley aberration method

1728, British astronomer bradley used the aberration method of stars to draw the conclusion that the speed of light is a limited physical quantity again. When observing the stars on the earth, Bradley found that the apparent position of the stars was constantly changing. Within a year, all the stars seem to revolve around an ellipse with an equal semi-long axis at the zenith. He believes that this phenomenon is due to the fact that it takes some time for the light emitted by the stars to reach the ground, but during this time,

3. Galileo's method of measuring the speed of light

In the history of physics development, it was the Italian physicist Galileo who first proposed to measure the speed of light. 1607 in his experiment, two distant observers were given a lamp that could be shielded. Observer a turns on the light. After a period of time, the light reaches observer B, and he immediately turns on his light. After a certain time, the signal returns to A, so A can record the time interval T from the time when he turns on the light to the time when the signal returns to A from B. If the distance between two observers is S, the speed of light is C = 2s/t. ..