Physics in Spacetime
The equations of special relativity can be written in a manifestly covariant form. The position of an event in spacetime is given by a contravariant four vector with components:
We define x0 = ct so that the time coordinate has the same dimension of distance as the other spatial dimensions; so that space and time are treated equally. Superscripts are contravariant indices in this section rather than exponents except when they indicate a square (it should be clear from the context). Subscripts are covariant indices which also range from zero to three, as with the four-gradient of a scalar field φ:
Read more about this topic: Special Relativity
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“We must be physicists in order ... to be creative since so far codes of values and ideals have been constructed in ignorance of physics or even in contradiction to physics.”
—Friedrich Nietzsche (1844–1900)