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Answer: Invariance of the speed of light in vacuum </h2>
Special relativity was proposed on 1905 by Einstein, who developed his theory based on the following two postulates:
<em>1. The laws of physics are the same in all inertial systems. There is no preferential system. </em>
<em>2. The speed of light in vacuum has the same value for all inertial systems. </em>
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Focusing on the first postulate, it can be affirmed that any measurement on a body is made with reference to the system in which it is being measured.
In addition, it deals with the <u>dilation of time</u> stating that <u>time passes at different rates in regions of different gravitational potential</u>. That is, the greater the local distortion of space-time due to gravity, the slower the time passes.
On the other hand, following what relativity establishes, bodies within a gravitational field follow a curved space path.
, we have