A spacetime diagram is a diagram that shows the effects of special relativity. It looks like a rectangular coordinate system, with the vertical axis being "ct" (speed of light multiplied by time) and the horizontal axis being "x" (position). | A spacetime diagram is a diagram that shows the effects of special relativity. It looks like a rectangular coordinate system, with the vertical axis being "ct" (speed of light multiplied by time) and the horizontal axis being "x" (position). |