MTL - Bringing the Supermarket to the Apocalypse-Chapter 419 Time and space

Usually, to determine the size of an object, its shape and size are known. 》

For a cuboid, know its length, width, and height, and calculate the volume using the Euclidean geometry formula. Just know that it is relative to the up, down, left, and right and left distances of another negligible size of the static reference. A few miles of geometry is enough.

Describe the instantaneous position of a moving object is not enough, you need to know the instantaneous speed and acceleration. Thus, the concept of a three-dimensional space coordinate system and one-dimensional time coordinates can be abstracted. The nature and laws of the motion of objects are closely related to the measurement of the spatial coordinate system and time coordinates. In order to determine the inertial system, l. Newton abstracts the concept of three absolute spaces and one absolute time. The absolute space satisfies the three-dimensional Euclidean geometry, and the absolute time passes uniformly. Their nature is independent of any specific object and its motion. The object that is moving in a stationary or uniform linear motion relative to the absolute space is the coordinate system of the reference object, which is the inertial system.

In classical mechanics, any object satisfies the Galilean transformation between the spatial coordinate quantity and the time coordinate quantity of different inertial coordinate systems. Under this set of transformations, the position and velocity are relative; the space length, time interval, and acceleration of the moving object are absolute or constant. The simultaneity in time measurement is also invariant; it is constant relative to whether two events of an inertial frame of reference occur simultaneously. Two events occurring simultaneously with respect to one inertial frame of reference, two events occurring simultaneously with respect to one inertial frame of reference, must also be simultaneous with respect to other inertial frame of reference, called the absoluteity of simultaneity. All laws of Newtonian mechanics, including the law of universal gravitation, are invariant under the Galilean transformation. This can be abstracted into the principle of Galilean relativity; the law of mechanics is invariant under the transformation of the inertial frame of reference. At the same time, invariance is closely related to the law of conservation. The time-translation invariance of a moving object under Galilean transformation corresponds to the conservation of energy of the object; the spatial translation and spatial rotation invariance under Galileo transformation correspond to the conservation of momentum and the conservation of angular momentum of the object.

If there is absolute space, the motion of the object relative to the absolute space should be measurable. This is equivalent to requiring certain degrees of mechanical motion to contain absolute speed. However, there is no absolute speed in the laws of science. In other words, the correctness of the laws of the last days does not require absolute space.

According to this type of transformation, the length and time interval of the ruler (i.e., the speed of the clock) are not constant; the ruler of high speed movement becomes shorter with respect to the stationary ruler, and the clock of high speed movement becomes slower than the stationary clock.

Simultaneity is no longer constant (or absolute); two events that occur simultaneously for one inertial frame of reference do not occur simultaneously with another high-speed motion of the inertial frame of reference.

In the special theory of relativity, the speed of light is an invariant, so the time-space interval (referred to as space-time interval) is also an invariant; some inertial systems, except for energy conservation and momentum conservation corresponding to time translation and spatial translation invariance, There is also a time-space translation invariance; thus, there is an energy-moment conservation law. According to this conservation law, the mass-energy relationship can be derived. This relationship is extremely basic in atomic physics and nuclear physics.

The principle of special relativity requires that all physical laws have the same form for the inertial reference frame. However, incorporating the law of gravity into this requirement does not correspond to the observations.

According to the general theory of relativity, if the inertial force or gravitational interaction between objects is considered, there is no large-scale inertial frame of reference, and there is only a local inertial system at any time and space point; between the local inertial systems of different time and space points, through inertia Force or gravity is related to each other. The space-time with inertial force is still a straight four-dimensional Kyivsky time and space.

There is a space-time of the gravitational field, which is no longer straight. It is a four-dimensional curved space-time, and its geometric properties are described by the four-dimensional Riemannian geometry of the metric with symbol difference. The degree of curvature of time and space is determined by the gravitational field equation of the energy-momentum tensor in which matter (object or field) and its motion.

In general relativity, time-space is no longer just a "stage" of object or field motion, and bending time - space itself is the gravitational field. The nature of the time-space characterizing gravity is closely related to the nature of the objects and fields in which it moves.

On the one hand, the energy-momentum of the object and the field motion is used as the source of the gravitational field. The field equation is used to determine the strength of the gravitational field and the degree of bending of the instantaneous space. On the other hand, the geometrical properties of the curved space-time also determine the object and field in which the motion is moving. The nature of the sport.

For example, the sun acts as a source of gravitational field, and its mass causes the time and space of the sun to bend, and its degree of curvature characterizes the strength of the solar gravitational field. The trajectory of Mercury, which is closest to the Sun, is most affected, and the starlight passing through the edge of the Sun is deflected, and so on.

Soon after the introduction of general relativity, astronomical observations show that the theoretical calculations of general relativity are consistent with the observations.

The understanding of space and time has always been closely related to the understanding of the universe. Modern cosmology is based on the principles of cosmology and Einstein's gravitational field equations.

The principle of cosmology believes that the universe as a whole evolves in time, that is, there are time arrows, which are uniform and isotropic in space.

The spatial position and momentum, time and energy of the system described by quantum mechanics cannot be accurately measured at the same time. They satisfy the relationship of uncertainty; the classical orbit no longer has precise meaning. How to understand quantum mechanics and the essence of measurement has been debated. In the end times, research on quantum entanglement, quantum teleportation, and quantum information has brought new problems and challenges to important concepts such as causality and locality, which are closely related to time and space.

The combination of quantum mechanics and special relativity leads to the quantum electrodynamics, quantum field theory, and electroweak unified model, including the standard model describing the quantum chromodynamics of strong action. Although it has achieved great success, it also brings some challenges. Difficulties. While profoundly changing some important concepts about time-space, it also brought some principle problems.

If the vacuum is not empty, there is zero energy and vacuum fluctuation, which greatly changes the understanding of physics in vacuum.

On this basis, the calculation of the quantum electrodynamic perturbation theory can give the results that are in good agreement with the experiment. However, this perturbation expansion is unreasonable. The mechanism of symmetry breaking leads to the mass of the weakly acting intermediate boson. However, the vacuum expectation of the Hagers field and the aforementioned zero energy are equivalent to the common sense of the universe in a certain sense, but the value is better than that of astronomical observation. Cosmological constants range from tens to more than a hundred orders of magnitude.