Nikolai Lobachevsky is one of the creators of non-Euclidean geometry. He suggested that parallel lines may intersect, and tried to prove that this was impossible, but the formulas suggested otherwise, and it turned out that this is actually possible. Thus, Lobachevsky proved the geometry that is familiar to us is not the only possible one. In physics, Lobachevsky's geometry is used at those scales where velocities approach the speed of light.

This portrait of Nicholas Lobachevsky is drawn with curved rulers, symbolising the curved space of non-Euclidean geometry.

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