Hello, First of all, I'm sorry since I bet there are quite a few threads about this but I still have a bit of a hard time wrapping the axes of the Minkowski diagram around my head. I understand very well that, to have the speed of light traveling at a 45 degree angle in a space-time diagram, one could change the time (t) and distance (x) axes in 2 ways since the length of each t and each x unit are the same in the diagram: 1. Change the t units into time units in which light travels one x unit distance, thus the vertical t axis having units of x / c time. (since distance / velocity equals the time that the speed of light travels one x distance) 2. Change the x units into distance units that light travels in one unit time, thus the horizontal x axis having units of c ⋅ t distance (since velocity times time gives the distance) However, I can't for the life of me get how a time axis of c ⋅ t would give a 45 degree angle of the speed of light as well. I know that c ⋅ t will give a distance unit but that means that the space-time diagram will have 2 distance axes. How can light (or anything else for that matter) therefore travel at a distance unit per distance unit?? Looking at it this way would make me say that for each square in the diagram, light travels a 300.000.000m per meter which is hard for me to understand. Is there a clear way to explain the meaning of 2 distance axes and, maybe formula wise, to explain why lightspeed would have a 45 degree angle in such a case? I'd appreciate the help a lot.