As with relativism in a narrow sense, the complete system of theory of relativity in a broad sense is also based on two core principles, namely, the principle of condensity in a broad sense and the principle of equivalence, which are the logical building blocks of relativity in a broad sense and the key entry point to understanding the core content of the doctrine. In 1915, einstein formally completed the construction of a broad relativity theory, which completely broke the absolute temporal and gravitational vision of newton mechanics, which has lasted for more than 200 years, and which is the fundamental starting point of einstein's theory of the core equation of broad relativity. We have learned before that narrow relativism is based on relativism and the constant speed of light, and applies only to the particular scenes of the inertial reference system, while two fundamentals of broad relativity have broken this limit, allowing the theory to apply to all reference systems in the universe。
2. In order to understand the broad principle of coherency, we should first recall the theory of relativity in narrow relativity and the concept of inertia that is closely related to it. In narrow relativism, we call it the inertial reference system, known as the inertial system, where only flat-speed straight motion does not exist. The central expression of the principle of relativity is that the laws of physics are identical in all inertial reference systems. In other words, if the two closed laboratories only have a relatively flat-speed straight-line movement without any acceleration or deceleration, the results of the identical physical experiments conducted in the two laboratories will be fully consistent. This doctrine is the core foundation of narrow relativity, but it also places clear limits on narrow relativity: the theory applies only to the particular scenario of the inertial reference system and does not address the problem of the non-inertial system of acceleration。
3 the broad principle of symmetry is essentially a more general principle of relativity, which einstein has often referred to as “a broad principle of relativity” in the construction of the doctrine. Its core content can be summarized as follows: in any reference system, the laws of physics take exactly the same form, regardless of how they interact with each other. The relativist principle of narrow relativism requires only that the laws of physics remain unchanged in the inertial reference system, while the principle of broad competitivity completely breaks down the special position of inertia in physics and extends its application to all reference systems, whether the inertial system of the pacing movement or the existence of an accelerator, or a non-inertial system of motion. This doctrine also addresses the long-standing logical flaw in newton mechanics and narrow relativism: the difficulty of inertia cannot be strictly defined。
4. The second core principle of relativity in the broad sense is the principle of equivalence, which is expressed at the core: the mechanical effects of acceleration, and those of gravity, cannot be distinguished by any experiment. In order to visualize this principle, we can use einstein's classic closed elevator idea experiment. Assuming that you are in a completely closed lift car without seeing anything outside, the first scenario is that the elevator is still on the surface of the earth, and you feel you're being pulled by a force to the ground of the elevator, and your feet can feel a clear weight, while you find that any object that goes free will accelerate its movement to the surface at a speed of 9. 8 metres per second, which is the gravity effect that we feel on a daily basis。
Five, we look at the second completely different scenario, the same thing as this closed lift car, where you can still see nothing from the outside, when the elevator and you are in a completely empty space in the universe, far from any celestial object, and not affected by any gravity field, but the elevator is accelerating at an acceleration rate of 9. 8 metres per second, in the direction of pointing from the ground to the ceiling. At this point in the elevator, you will still feel you are being pulled by a force towards the surface of the car, your feet will feel exactly the same weight on the surface of the earth, and objects that fall freely will continue to move towards the surface at an acceleration rate of 9. 8 metres per second. You can't tell whether you're still in the earth's gravity field, or whether you're moving faster in space without gravity, through any mechanical experiments done in the elevator。
6. In fact, the strong correlation between the effects of gravity and the effects of acceleration has long been found in newton's classic system of mechanics, which is essentially equivalent to the strict mass of gravity of objects and inertia. In newton mechanics, inertial mass describes the object's resistance to acceleration, and gravity mass describes the strength of the object's gravitational effect, which has a completely different physical significance, but experimental measurements find that their values are identical. In newton mechanics, however, this equivalence is seen as a coincidence and is not given a deeper physical meaning. Einstein, on the other hand, has aptly grasped the coincidence and elevated it to the basic principle of general relativism, arguing that there is no difference in the nature of the two effects。
7. Starting with the late 19th century experiments, a large number of high-precision physical experiments over a hundred years have proved the equivalence of gravity and inertia, providing a solid empirical support for the principle of equivalence and making it one of the most solid foundations of general relativity. And the two fundamental principles of broad competitivity and equivalence are the logical starting point for einstein to deduce the core equation of broad relativity. On the basis of these two principles, einstein, by rigorous mathematically deduced, eventually received the core equation of a broad relativity, which directly linked the curvature of time and space to the distribution of material energy in the universe, completely recasting human perception of gravity: gravity is not the force of hyperdistance between objects, but the geometric effect of the presence of the substance that causes a time and space curve。
8. The many predictions of broad relativism based on these two fundamental principles have been confirmed over the centuries by numerous astronomical observations and physical experiments, further confirming the validity of both principles. In 1919, astronomer eddington validated the convulsion of the broad relativity prophecy in the solar gravitational field, allowing for global acceptance of the broad relativism; followed by precise calculations of anomalies in the near-day movement of mercury, ground and astronomical observations of the gravitational red movement phenomenon, first direct human detection of gravitational waves in 2015, and the photographing of the first black hole in 2019. These two fundamentals not only reshape the gravitational theory of modern physics, but also profoundly alter human perceptions of the nature of time and space and the evolution of the universe。
