The Squeezing of Space
Just as velocity warps time, it also warps physical space. Length Contraction (or Lorentz-FitzGerald contraction) is the phenomenon where a moving object appears to shrink in the direction of motion as measured by a stationary observer.
If a spaceship flies past Earth at near light-speed, an observer on Earth will see the spaceship literally squashed flat along its direction of travel.
The Illusion of Rigidity
Length contraction proves that physical dimensions are not absolute properties of an object. The length of a car depends entirely on who is measuring it and how fast they are moving relative to it.
Importantly, length contraction only occurs in the direction of motion. If a spherical spaceship flies past you at 99% the speed of light, it will look like a flattened pancake, not a smaller sphere.
The Formula
Example Calculation
A spaceship is exactly $100 , \text{meters}$ long when parked (Proper Length, $L_0$). It flies past a space station at 86.6% the speed of light.
- Calculate the Lorentz Factor denominator: $\sqrt{1 - 0.866^2} \approx \sqrt{0.25} = 0.5$.
- Multiply: $100 \times 0.5 = 50 , \text{meters}$.
To the people on the space station, the ship is only $50 , \text{meters}$ long. However, to the pilot inside, the ship is still $100 , \text{meters}$ long.