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relativity

Einstein’s mass-energy and kinetic energy

Andrew James Steinmetz

It’s easy to notice that the famous equation \(E = mc^2\) is similar to the classical expression for kinetic energy \(T = \frac{1}{2}mv^2\). Both are proportional to mass, and both have a “speed” (\(c\) or \(v\)) which is squared. That they are alike might prompt the question: why doesn’t...

What is time?

Jason K. Resch

Download eBook Watch Episode What is time? Few things are so familiar and mysterious. Our lives are governed by time, and yet we have so little understanding of it. In many ways time behaves like a dimension. We move through and have a position in time, just as we move through and...