From the graph, we can see that length contraction is only significant when an object is travelling at speed beyond 10 to 20% that of the speed of light. Hence, we would not expect detectable contraction when a bus moves at 70 km/h (0.000000064c) in our daily lives, as a bus of 4.5 metres will appear shorter by less than the diameter of an atomic nucleus. The faster it moves, the shorter its length will become. At the speed of light, its length will be zero.
This effect is easily demonstrated with the SOL Control System. Let us watch a bus pass by in front of us with speed 4 metres per second, corresponding to 90% the speed of light.
Observe that the bus has been contracted in its direction of motion. By the formula above, its length has decreased by 44%.
By intuition, we may conclude that if a person is in the bus moving at a high speed, he will observe that the bus and everything inside it become compressed while the outside view remains unchanged. However, this is not what Special Relativity predicts. Lorentz contraction is a relative effect and not an absolute one. The person in the bus may regard himself as being stationary while the world outside is passing by in the opposite direction. Hence, the world would undergo Lorentz contraction and appear compressed to the observer. To illustrate this effect, let us get onto the bus and go for a short spin.
