A detailed and easy to understand introduction to Einstein s theory of relativity

The moving bell slows down, and the moving ruler becomes shorter.

Einstein's theory of relativity revealed: the special theory of relativity revealed the connection between space, time, mass, and the motion of matter; The general theory of relativity established the theory that space and time change with the distribution of matter and the speed of motion. Einstein's theory of relativity is a basic theory about space-time and the force of incendiary power, mainly founded by Albert Einstein, and is divided into special relativity (special relativity) and general relativity (general relativity).

Applications of the theory of relativity.

The theory of relativity is needed whenever we study objects that are (a) moving in a strong gravitational field or (b) moving at close to the speed of light.

If (b) is true, but (a) is not, we can use a simpler version of the theory that calls the knower a special theory of relativity;

Historically, this was first developed by Einstein, while the broader theory of general relativity came later.

Neither (a) nor (b) is true in everyday life on Earth, so we usually don't have to worry about relativity at all.

Still, its effectiveness is important when extreme precision is required.

For example, one of the most important applications of the theory of relativity involves the Global Positioning System (GPS), which simply cannot work if we do not consider the relativistic effect.

Einstein's theory of relativity revealed the relativity of time and space.

The relativity of space-time refers to the fact that the specific space-time of each specific thing is temporary, conditional, and relative, and the specific characteristics of time-regret and space-time change with the change of the state of material motion. Einstein's theory of relativity reveals this philosophical connotation from a scientific point of view.

It is generally accepted that the difference between special and general relativity lies in whether the problem under discussion involves gravity (bending space-time), i.e., special relativity only deals with those problems where there is no gravitational force or the gravitational effect can be ignored, while general relativity deals with physics when gravity is involved.

In the language of relativity, the background space-time of the special theory of relativity is straight, that is, the four-dimensional trivial manifold is matched with the Min's gauge, and its curvature tensor is zero, also known as the Min's space-time; The background space-time of general relativity, on the other hand, is curved, and its curvature tensor is non-zero.

Applications of the theory of relativity.

1. The atomic clock on the satellite of the Global Positioning System (GPS) is very important for accurate positioning. These clocks are affected by both the slowing down of time due to the high speed of motion due to special relativity and the faster time effect of general relativity due to the weaker gravitational field (day).

The net effect of relativity is that those clocks run faster than terrestrial clocks. As a result, the software of these satellites needs to calculate and cancel out all relativistic effects to ensure accurate positioning.

2. The algorithm of the global positioning system itself is based on the principle of invariance of the speed of light, if the principle of invariance of the speed of light is not true, then the global positioning system needs to be replaced by a different algorithm to be accurately positioned.

Albert Einstein once said that if you sit with a beautiful woman, you will feel that time flies, but if you sit with an ugly woman, you will feel that time is unbearably slow, and this is the theory of relativity. The motion of an object is relative and depends on the frame of reference you take. The measure of time and length in each frame of reference for relative motion is not the same.

For example, Cuba's Robles broke Liu Xiang's world record in the 110-meter hurdles some time ago, but those in a spaceship moving close to the speed of light relative to the Earth will think that he did not break the record, and those on the spacecraft measured that he would have taken longer to reach the finish line. This is because in frames of reference that move close to the speed of light, the measure of time becomes longer. In the same way, if you are wearing 25 cm shoes, the length of the shoes you are wearing by someone on a spaceship may only be 20 cm.

Another point is that the high-speed motion does not change the simultaneity of the event, and the two cars that reach the end at the same time appear to arrive at the same time on the ship. However, the order in which events occur at different times may be reversed, and the people on the ship may see that you eat the apple first, and then see the apple fall to the ground.

To put it simply, use a popular algorithm (in junior high school physics): if you fly forward at half the speed of light and observe another beam of light.

That beam of light should be half the speed of light.

This is not consistent with the experiment.

Light always moves only at the speed of light.

Even if you run forward at the same speed as that light.

That light is not still relative to you.

The answer to Einstein's formula is the speed of light.

This formula also brings the strange result that the faster the movement, the shorter the length, the slower the time, and even the e=mc*c can be deduced

But these seemingly impossible results were proved by experiments that observed the motion of particles at high speeds, and Einstein's formula was demonstrated.

The theory of relativity has greatly changed mankind's "common-sense" concept of the universe and nature, and has put forward new concepts such as "simultaneous relativity", "four-dimensional space-time", and "curved space-time". It developed Newtonian mechanics and propelled physics to a new level.

Fundamentals of Special Relativity:

1. In any inertial frame of reference, the laws of nature are the same, which is called the principle of relativity.

2. In any inertial frame, the vacuum speed of light c is the same, that is, the principle of invariance of the speed of light.

The first of these is the principle of relativity, and the second is the invariance of the speed of light. The whole theory of special relativity is based on these two basic principles. It follows that when the quantities of time and space are transformed from one inertial frame to another, the Lorentz transform should be satisfied, not the Galilean transform.

And from this leads to many important conclusions, such as:

1. The sequence of the occurrence of the two events or whether they are "simultaneous" is different in different frames of reference (but the law of cause and effect still holds).

2. When measuring the length of an object, the length of the moving object in the direction of motion will be shortened compared with that at rest. Similarly, when measuring the time process, you will see that the moving clock is progressing more slowly than the stationary clock.

3. The mass m of the object increases with the increase of velocity v.

4. The speed of any object cannot exceed the speed of light.

5. The mass-energy relation between the mass m and the energy e of the object satisfies the mass-energy relationship e=mc2.

The above conclusions are consistent with the current experimental facts, but the effect is only significant when moving at high speeds. In general, relativistic effects are so small that classical mechanics can be considered an approximation of relativistic mechanics at low speeds.

Fundamentals of General Relativity:

1. The principle of general relativity, i.e., the laws of nature can be expressed in the same mathematical form in any frame of reference.

2. The principle of equivalence, that is, the gravitational force in a small volume range and the inertial force in a certain acceleration system are equivalent to each other.

According to the above principle, the gravitational force arises due to the existence and certain distribution of matter, which makes the properties of time and space uneven (the so-called space-time curvature); and thus established the theory of gravitational field; Special relativity, on the other hand, is a special case of general relativity when the gravitational field is weak.

When you hold this red iron plate in your hand, you will feel that 1 second is like 1 hour, and when you hold this beautiful woman, you will feel that 1 hour is as short as 1 second.

The main points include the narrow relativity theory and the broad sense of the relativity theory, and the differences between the narrow sense relativity theory and the broad relativity theory are.

The former discusses the physical laws between the reference frames of uniform linear motion (inertial reference frames), while the latter extends to reference frames with acceleration (non-inertial frames) and under the assumption of equivalence principles. It is widely used in gravitational fields. The most well-known corollary of the special relativity theory is the mass energy formula, which can be used to calculate the energy released during the nuclear reaction process and led to the birth of the atom bomb. Gravitational lenses and black holes, as predicted by generalized relativity, have also been confirmed by astronomical observations.

I only knew a little bit about this, and then I looked up some on the Internet.

e=mc*c.When the velocity reaches close to the speed of light, the mass of the object will change