The 2 posters who note the proof’s division by zero are correct. Division by zero is prohibited. Congratulations to those 2 posters.
A few years ago I taught a graduate-level Cost Accounting course, and I put that proof on the blackboard. No student saw the flaw, and no one in the class pursued the matter even though common sense says that 2 of anything cannot be equal to 1 of the same thing. Moreover, no student in that class had heard of Socrates. How does one complete 16 years of schooling without at least having heard of Socrates?
The Lorentz transformation, which is a consequence of Einstein’s theory of special relativity, has a term that is 1 divided by the square root of 1 minus v squared over c squared, where c is the speed of light and v is the velocity of a moving body. As v approaches c, the denominator of the quotient approaches zero. V cannot reach c (otherwise division by zero would occur), which implies that nature has a built-in speed limit, it being the speed of light.