Is there a reason to why the world line for light is oriented at 45 degrees to the axes?
2007-01-21 12:08:42 · 1 answers · asked by sh 1 in Science & Mathematics ➔ Astronomy & Space
That represents the equation of motion of a photon, which is travelling at the speed of light. That is, x = c t, where x is position, c is the speed of light, and t is time. The slope is "c" here, but frequently, when relativists work with spacetime diagrams, they just let c =1 to make things simpler, without any loss of generality. Hence, we end up with the equation x = t, and that's where you get your 45 degrees.
Commonly with these spacetime diagrams, the t axis is vertical, so there aren't any real paths below this line at 45 degrees, because that would mean it's going faster than the speed of light. That's the reason for speaking about "light cones", when this same graph is generalized to include the other dimensions y, and z. Nothing can travel "outside the light cones".
2007-01-21 12:15:31 · answer #1 · answered by Scythian1950 7 · 2⤊ 0⤋