Education News

Archive for the ‘Science’ Category

According to the laws of motion first established in detail by Isaac Newton in 1680-89, two or more movements are added according to the rules of arithmetic. Suppose a train passes by us at 20 mph and a child throws a ball off the train at 20 miles per hour in the direction of motion of the train. For the child who moves with the train, the ball moves at 20 miles per hour. But for us train movement and the ball are added, so the ball will move at the speed of 40 miles per hour.

As you see, can not speak of the speed of the ball to dry. What counts is its speed relative to a particular observer. Any theory of movement attempts to explain how the speed (and related phenomena) seem to vary from one observer to another would be a “theory of relativity.”

The theory of relativity Einstein was born the following fact: what works for balls thrown from a train does not work for light. In principle it could be that the light spread, or for the earth’s motion or against it. In the first case would seem to travel faster than the second (the same way that a plane travels faster in relation to the ground when you carry a tailwind as when it is facing). However, very careful measurements showed that the speed of light never varies, whatever the nature of the motion of the source emitting the light.

Einstein then said, suppose that when measuring the speed of light in vacuum, it is always the same value (about 299,793 miles per second) in all circumstances. How can we have the laws of the universe to explain this? Einstein found that to explain the constancy of the speed of light had to accept a series of unexpected events.

He found that objects had to be shortened in the direction of movement, especially as most were its speed, and finally to zero in a length limit of the speed of light the mass of moving objects had to increase with speed to be infinite in the limit of the speed of light, that over time a moving object was getting slower with increasing speed, up to stop at this limit, the mass was equivalent to a certain amount of energy and vice versa.

All this developed in 1905 in the form of the “special theory of relativity”, which dealt with a constant velocity of bodies. In 1915 drew even more subtle consequences for objects with variable speed, including a description of the behavior of gravitational effects. It was the “general theory of relativity.”

The changes predicted by Einstein are only noticeable at high speeds. Such speeds have been observed between the subatomic particles, finding that the changes were predicted by Einstein really, and with great accuracy. Moreover, if the theory of relativity Einstein was wrong, particle accelerators could not function, atomic bombs would not explode and certain astronomical observations impossible to do.

But running speeds, the predicted changes are small enough to be ignored. In these circumstances governing the numeracy of Newton’s laws, and as we are accustomed to the operation of these laws, we now seem “common sense”, whereas Einstein’s law seems to us “weird.”