Theory of Relativity is a set of studies by the German physicist Albert Einstein (1879-1955), which define a relationship between space and time, both of which are relative and not static.
Briefly, the Theory of Relativity states that time is not the same for everyone, and it can change according to three variables: speed, gravity and space.
Einstein's Theory of Relativity is formed by joining two other theories:
- Restricted (or Special) Relativity Theory: first published in 1905.
- General Theory of Relativity: published in 1915.
Physicist Albert Einstein: creator of the Theory of Relativity.
Theory of Restricted Relativity
The main idea of Restricted Relativity is that the speed of light is an equal constant for the entire universe. This concept also states that space and time are not absolute quantities, but totally subjective.
Among its main assumptions, the theory of General Relativity states that gravity is nothing more than the distortion that a given mass causes in the “tissue” of space.
When an object moves at great speed through space, so-called gravitational waves are created.
Postulates of the Theory of Restricted Relativity
The Theory is based on two postulates:
- The laws of physics are the same in any inertial frame.
- The speed of light in a vacuum (300,000 km/s) is the same in all inertial frames.
The Theory of Restricted Relativity is based on references from inertia, that is, those related to Newton's First Law (or law of inertia). According to this law, bodies tend to keep moving with speed or at rest if no force is applied to them.
Example of the Theory of Restricted Relativity
A very famous example that helps to clarify some of the principles of the Theory of Relativity is the Gemini Paradox.
The example describes two twins on Earth, one of whom is put on an aircraft heading to a distant location in the galaxy. It travels at the speed of light while the other stays on the planet.
When he returns to Earth, the traveling brother will be many years younger than the other.
This would happen because time passes faster when a body remains in inertia, however, this time decreases proportionally to the speed that an object moves. When you reach the speed of light (approximately 1.07 billion km/h), time simply stops passing.
General Relativity Theory
This theory was developed by Einstein ten years after the publication of the Theory of Restricted Relativity, from the change of the observed referents - until then inertial. At that moment, unlike what he did in the previous theory, he started to consider the so-called non-inertial referents.
The biggest difference from the Restricted Theory it is your perception of curved space (or curvature). Einstein observed that the existence of matter was capable of causing a curvature in the notion of space and time.
He found that there is a curvature that is produced around the bodies, which is proportional to the mass of the body. Thus, he concluded that: the greater the mass of a given body, the greater the space-time curvature.
See too:
- Newton's Laws
- Newton's First Law
- Newton's Second Law
- Newton's Third Law.
