Friday, December 14, 2012

Physics Phriday

Take your time on this one, as many times as you wish.

The first image is a model of a 1+1 dimensional spacetime, the time axis is vertical, the x axis is horizontal, the speed of light is 1, the orange cone is the light cone and the blue line is the world line of any physical object. At any point on it the world line is confined to the future (+) and past (-) of the light cone at that point, and the point always moves forward in time.

In the second image, I've done some "manifold surgery": I've made a cut each at t = -1 and t = +1 each of which extends from x=1 to x=3. Now I restitch them, but stitch the bottom edge of the lower cut to the top edge of the upper cut, and also the top edge of the lower cut is stitched to the bottom edge of the upper cut.

What have I built?


Reg Gilbert said...

Not that I will ultimately have any idea how to answer this, but 1) I see no orange cone (is it something to do with that big red x across the wavy blue line?), and 2) I can't figure out what information "the x axis is horizontal" was supposed to convey -- should it say something like "the world is the horizontal axis"?

Ranjeet said...

Hi Reg,
1. What looks like an orange "X" with two diagonal lines is the cross section of a double cone, parts of the figure weren't reproduced correctly.
2. The X-axis is the space axis, so yes, a spatial slice of our world is horizontal.