What Is a Gravitational Field?

A gravitational field is a theoretical model that describes how an object extends into space and has an attractive effect on another object. The modern point of view is that the gravitational field is the space bending effect produced by matter in space. When the object moves in the curved space, the movement state of the space in the right angle space changes, thus reflecting the gravitational effect. Quantitative descriptions of gravitational fields are found both within the classical theoretical framework of Newtonian mechanics and under the framework of Einstein's theory of general relativity. However, it is found that the motion of interstellar matter in the universe is inconsistent with existing theories through modern observation methods, so the concepts of "dark matter" and "dark energy" are introduced to bridge the gap between the original theory and actual observation. Although the academic community has begun to study the possible quantities, distributions and properties of dark matter and dark energy, they are still unknown concepts that are greater than known and have not yet been fully proven.

Gravitational field

Newton used the law of universal gravitation to describe the gravitational effect between objects in the classical mechanics system, and the particularity of this interaction is that it is only related to the mass of objects and the distance between objects. In the law of gravity, gravity is described as a point-to-point interaction between any two objects with mass in space (see

Scientists have repeatedly confirmed through various observations and calculations that dark energy dominates the universe, accounting for 73%, dark matter accounts for nearly 23%, and materials we are familiar with account for only about 4%. So the movement of the universe is not driven by matter that we are familiar with, but by dark energy. The motion of the solar system and the galaxy is vortex, so dark energy must be a

The gravity of an object is generated by the gravitational field. Without a gravitational field, there is no gravity in an object. Therefore, gravity is not an attribute of the object itself, but it is not an attribute of the gravitational field itself. The body itself does not produce gravity, nor does the gravitational field itself. The gravity of an object is the product of the interaction of the gravitational field and the mass of the object. The theory of universal gravitation actually equates gravity with gravity. It also regards the mass of an object as the main factor that generates the gravitational field, so it is not clear what gravity is and what gravity is. In other words, it cannot explain the gravity of an object. You can use the following formula to calculate the gravity of an object:

P = G2mF (2)

In formula (2), P represents the gravity of the object, m represents the mass of the object, F represents the gravitational force of the body in the vortex field, and G2 is a gravity constant.

The formula (2) means that the gravity of an object is proportional to the product of the mass of the object and the gravitational field of the gravitational field.

Gravity equation

Gravity G1 and gravity G2

The average speed of the earth's movement around the sun is represented by V1, and its average orbit radius is represented by R1. Then there is V1 = 29790 m / s, R1 = 1.49597870 × 1011 meters, and the mass of the earth is M0. According to the principle that the centripetal force of the earth moving around the sun is equal to its centrifugal force, the following formula can be obtained:

=

R1V12 1.49597870 × 1011 × (29790) 21 2.209146 × 1010

G1G2 = = ==

MnM (17796M0) × (337691M0) M0 × M0

The mass of the earth, M0 = 589 × 1024kg, is substituted into the above formula. After calculation, we get:

G1G2 = 6.36786 × 10-38 (4)

The unit of the gravitational force F is kg / m2, which means that the gravitational force in the gravitational field is reduced by the square of the height. There must be no unit of time in the unit of gravity, because the gravitational field in the gravitational field is independent of time. The unit of G1 is kg-1, and the unit of G2 is m3kg-1s-2.

Substituting gravity P = mg into formula (3) gives:

G2 = g / F (5)

Gravity in a gravitational field is a relative concept, not an absolute concept. We should set a standard for measuring gravity. This standard can be defined as follows: The gravitational force on the surface of the sun is set to 274 kg / m2, which is used as a measure of the gravitational force in the gravitational field. The gravitational acceleration of the sun's surface is 274 m / s ^ 2. According to this standard and formula (5), we get

Take the solar system as an example to illustrate the planet's centripetal force. The gravitational force in the gravitational field of the solar system can be calculated according to formula (1). The gravity P of the planets in the gravitational field of the solar system can be calculated according to formula (2). Substituting formula (1) into formula (2), the following formula can be obtained:

P = G2mF =

(3)

In the gravitational field of the solar system, the direction of the gravity of the planet is directed to the sun, so the gravity of the planet can also be called the planetary orbit

Scientists can use the gravitational formula to calculate the centripetal force of the earth's movement around the sun, and the calculation result is expressed by F0. The above-mentioned formula (3) can also be used to calculate the centripetal force of the earth's movement around the sun, and the calculation result is represented by P0. By comparison, it will be found that F0 = P0. Why do two different theories have the same result? The reason is simple: theoretical imperfections can often be corrected with constants in the formula. Because this constant is the result of a lot of experiments and calculations by scientists, it is correct.

In the same gravitational field, as in the gravitational field of the solar system, the universal gravitational constant G is a constant value. But in different gravitational fields, the G value is different. when

According to the law of universal gravitation (the law of inverse square), the strength of the gravitational field is the basic physical quantity describing the nature of the gravitational field, and it is a vector. It is exactly equivalent to the electric field strength.

The intensity E of the gravitational field at an observation point in the gravitational field is equal to the ratio of the gravitational force F to the mass m received by the stationary mass m placed at that point.

The unit of gravitational field strength should be Newton (ton) per kilogram. In the SI system, the symbol is N / kg. If the gravitational force of a 1kg particle at a point in the gravitational field is 1N, the gravitational field strength at this point is 1N / kg. If the earth's surface is taken as the research object, its gravitational field strength is g, which is the magnitude of gravity acceleration. However, the strength of the gravitational field is not equal to acceleration.

In general relativity, the gravitational field is described as space-time bent by mass, so the "strength" of the gravitational field can be described by the gauge tensor on the left side of the equation. The metric tensor uniquely determines the geometric properties of space-time. For Minkowski space-time (time and space without gravity, that is, the four-dimensional space-time of special relativity studies), the metric g (11) =-c ^ 2, g (22) = g (33) = g (44) = 1, the rest g (ij) = 0.