Einstein’s Special Theory of Relativity

Before we explain this theory, you must have in mind something:

There are 2 postulates:

  1. Objects move relative to each other. If you are in a moving car, while reading this article, then you don’t move relative to the driver, but you move relative to the ground or to the universe with a certain speed.
  2. The speed of light is constant in the universe and in astrophysics it’s notated with ‘c’.

Let’s say there is you and Einstein. You both have a light Clock which has a light beam bouncing between two parallel mirrors.

When you both stay on Earth without moving relative to it, both light beams travel the same distance.

Let’s say you remain on Earth and Einstein is traveling in the space with 90% of the speed of light, Einstein’s light beam would travel much faster than yours.

Though this contradicts the second postulate…

For the both speeds of the light beam to be the same, there must be another factor

And that is Time.

So it turn out the faster you move in space, the slower time passes. You experience this thing every day, but insemnificant. Differences of some nanoseconds.

Here is another example:

There are 2 twins on Earth, one of them goes on a spaceship, traveling with 80% light speed for 1 sec in total. When he comes back, his twin will be older with some years.

But how can we measure this?

Let’s note time on Earth with Te and time in space with Ts.

Te = Ts / √ 1-(v^2/c^2)

So 1 second of space travel with 0,8 c = 1,67 seconds on Earth.

And this is How you can be younger than your Twin 😉

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See you next time!