Relativity for Dummies

The thing behind the famous $E = mc^2$ thing no one understands.

(Einstein stuff)

What’s the Deal?

  1. The speed of light $c$ is a universal constant.
  2. You are always traveling through spacetime precisely at the speed of light.
  3. Spacetime is the creative result of shoving space and time into one concept.

What is Speed?

Speed is a distance traveled from point $p_1 \to p_2$ in space during the (non-zero) time period from $t_1 \to t_2$. It is usually expressed the following way algebraically:

$v = \frac{s}{t}$

In this equation, $v$ is velocity (speed in a direction), $s$ is the distance $p_2 - p_1$ and $t$ is the time period $t_2 - t_1$. Speed is a movement in both time and space.

Combining the Above

If you are always moving at the speed of light, then your $v = c$.

What If I am Standing Still?

We have to look at our simple equations again and perhaps rearrange them:

  1. The definition of speed: $v = \frac{s}{t}$

  2. Your movement in spacetime is always the speed of light: $v = c$

  3. That implies: $c = \frac{s}{t}$

As $c$ is a universal constant (extensively verified by experiments), the distance $s$ and the time $t$ always balance each other out resulting in the speed $c$. In other words, as speed is a movement in both space and time, then you are moving more in time than you are in distance should you be “standing still”.

(You never stop moving in time, or do you?)

What if I Travel Like Really Really Fast?

Let’s try and see what happens with some small numbers. The speed of light is a long nasty number, so I’ll just make the numbers nice to work with for the sake of the example:

  1. $c = 42$ # We declare the speed of light 42 something…

  2. $s = 21$ # and a motion in space 21 something.

  3. $c = \frac{s}{t}$ # Now we solve for $t$.

  4. $c = \frac{s}{t} \to ct = s \to t = \frac{s}{c}$ # Now plug in numbers!

  5. $t = 21 \div 42 = 0.5$

If we instead declared the motion in time as 21, the motion in space becomes 0.5.

Conclusion(s)

  1. You move less in time when you move more in space.
  2. You move more in time when you move less in space.