What are the two basic principles of special relativity?

In 1905, Albert Einstein proposed two hypotheses:

1。The principle of relativity: Physics has the same mathematical expression in all inertial frames of reference, that is, all inertial frames are equivalent for describing physical phenomena. (Absolutely).

Relativistic constraints and scalability.

Albert Einstein put forward two hypotheses:

1 The laws of physics have the same mathematical expression in all inertial frames of reference.

Problem: When an object falls freely from the roof of a car moving at a constant speed on the ground, the trajectory observed by the people in the car is not the same mathematical expression. I cannot use the simple unity of coefficients.

Question: Humans have never had a vacuum in the physical sense, and the conclusion is not debated. Is there a more general scope of application?

The revisions are as follows: 1 The laws of physics repeat experiments under the same conditions, with the same mathematical expression. Coordinate transformations can be used to convert between different reference systems.

2 In a homogeneous and stable medium, the velocity of motion of any wave is the same. In other words, the velocity of any wave is related only to the medium and not to the motion of the wave source after emitting the wave.

These two assumptions are in fact axioms, and no one will object to them, so there is no need to assume.

A brief history of natural life in the universe, your popular science primer丨Produced by scientific sound, it must be a high-quality product.

Special Relativity: Can It Reveal the Mysteries of Space and Time? One minute will take you to understand the special theory of relativity.

Special theory of relativityThe two basic principles are the principle of relativity in the narrow senseThe principle that the speed of light does not change

1. The principle of special relativity.

All laws of physics (mechanics other than gravity, electromagnetism, and other interacting dynamics) are valid in all inertial frames; In other words, the equations for all the laws of physics (except gravity) are transformed in Lorenz.

The form remains unchanged under the same. Experiments conducted at different times give the same laws of physics, which is the experimental basis of the principle of relativity.

2. The principle of invariance of the speed of light.

Light always travels at a definite velocity c in a vacuum, and the magnitude of the velocity is independent of the state of motion of the light source. In all directions in a vacuum, the speed of light propagation (i.e., the speed of light in one direction) is the same (i.e., the speed of light is the same as the residuality).

The speed of light is the same as the state of motion of the light source and the observer.

The inertial frame in which it is located has nothing to do with it. This principle is incompatible with classical mechanics. With this principle, it is possible to accurately define the simultaneity of different locations.

The basic principle of general relativity is the principle of equivalence: a reference frame with a uniform acceleration of linear motion with acceleration a is perfectly equivalent to a stationary local reference frame with acceleration g=a. In other words, a local frame of reference that falls freely in a gravitational field is perfectly equivalent to an inertial frame of reference without a gravitational field.

What exactly is Einstein's theory of general relativity?

The basic principles of special relativity are: (1) In all inertial frames, the fundamental physical laws are the same, which is called the special principle of relativity. (2) In any inertial frame, the speed of light in a vacuum is the same, is constant equal to c, and is independent of the motion of the light source, which is called the principle of invariance of the speed of light.

Therefore, it is concluded that when the quantities of time and space are transformed from one inertial frame to another, the Lorentz transform should be satisfied, rather than the Galilean transform, and many important conclusions are derived, mainly including: when measuring the length of an object, the length of the moving object along the direction of motion is shorter than that at rest, that is, the shrinkage effect; When measuring the time history of an object, the time course of the moving object is slower than the stationary time, and the moving clock travels slower than the stationary clock, i.e., the clock slowness effect. The mass of the object increases with the speed of motion; The total energy of an object with mass m is e=mc2 (mass-energy relation); It is impossible for any object to exceed the speed of light, c, etc., and these conclusions are consistent with the empirical facts of a large number of particles moving at high speed (close to the speed of light), especially in the release of atomic nuclear energy, the mass-energy relationship is concretized, which enables mankind to enter the age of atomic energy, and lays the foundation for the further development of the theory of electromagnetic field, nuclear force field and weak force field. The above theory starts from the principle of relativity and is only valid for inertial frames, which is called special relativity.

Special Relativity: Can It Reveal the Mysteries of Space and Time? One minute will take you to understand the special theory of relativity.

1. The principle of special relativity: all physical laws are valid in all hail index inertial frames; In other words, the equations of all physical laws remain unchanged in form under the Lorentz transformation. Experiments conducted at different times give the same laws of physics, which is the experimental basis of the principle of relativity;

2. The principle of invariance of the speed of light: light always travels at a certain speed in a vacuum, and the magnitude of the speed has nothing to do with the motion state of the light source. In all directions in a vacuum, the magnitude of the propagation speed of the optical signal is the same; The speed of light has nothing to do with the state of motion of the light source and the inertial frame in which the observer is located.

This principle is incompatible with classical mechanics. With this principle, it is possible to accurately define the simultaneity of different locations.

1. The principle of special relativity: all physical laws are valid in all inertial frames; In other words, the equations of all physical laws remain unchanged in form under the Lorentz transformation. Experiments carried out at different times give the same laws of physics, which are the experimental basis of the principle of relativity;

2. The principle of invariance of the speed of light: Li rotten light always propagates at a certain speed in a vacuum, and the magnitude of the speed has nothing to do with the motion state of the light source. In all directions in a megavacuum, the propagation velocity of the optical signal is the same; The speed of light has nothing to do with the state of motion of the light source and the inertial frame in which the observer is located.

This principle is incompatible with classical mechanics. With this principle, it is possible to accurately define the simultaneity of different locations.

Equivalence principle: The inertial mass is equivalent to the gravitational mass, which means that any point in the gravitational field is equivalent to a non-inertial frame.

Generalized covariance principle: In contrast to the special equivalence principle of special relativity (where all physical laws are formally consistent in any coordinate system), the generalized covariance principle states that all laws are consistent across all reference frames, not just inertial frames.