Time dilation simply explained: what is it anyway?

An important part of Einstein's theory of relativity is time dilation. You can find out exactly what this is in this practical tip.

Time dilation - what is it anyway?

Before we explain time dilation in detail, you need to know two things: 1. No object can be faster than light. 2. Light always has the same speed, namely 299792458 meters per second. You do not need more to understand the time dilation. We will explain it to you using the example of a so-called "light clock": This is a fictitious clock, in which light is always reflected back and forth between two mirrors, creating a fixed cycle.

• In our thought experiment, one of these clocks is mounted in a spaceship that does not move relative to us at any speed (V), so V = 0. Another spaceship with a light clock now flies past this spaceship at a speed (relative to the observer ) close to the speed of light, for example V = 0.99 ⋅ c.
• Now you have to get a little creative: imagine the light as a small dot. With a spaceship that does not move, the light can run completely vertically from top to bottom and back again. A distance corresponds to the distance between the mirrors. Since the second spaceship is moving, the light has to run diagonally in order to catch up with the flying spaceship. Here, the light has a long way to go because the speed of light c always remains the same.
• However, this phenomenon can also be applied to other physical processes. The faster the system moves relative to the observer, i.e. the faster the relative speed, the slower the other system appears to the observer and vice versa.
• This time can also be calculated using a simple formula. Here the formula ∆t '= ∆t: √ (1 - V²: c²) is used. However, note the point-before-dash calculation.
• In addition to normal time dilation, there is also gravitational time dilation, which also occurs in Einstein's general theory of relativity. Time passes more slowly in the vicinity of a strong gravitational field and consequently in the vicinity of a strong curvature of space. In contrast to normal time dilation, an observer who is further up in the gravitational field sees the time of the observer below that running more slowly, while the observer below sees the time of the other one running faster.

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In the next practical tip, we will explain how quantum computers work.