Example 2 (Speed of Light is Constant)
A skier skis downhill at 50 km/h and an avalanche behind him is moving at 60 km/h. The avalanche is therefore moving towards the skier at 10 km/h. If the skier stops the avalanche will be approaching the skier at 60 km/h.
* This demonstrates how Newtonian physics holds for velocities that are not too large. As you approach the speed of light Newton’s theories begin to break down.
If the avalanche is made of light it will always be moving towards the skier at the speed of light. No matter whether the skier is moving in the same direction as the avalanche or if he is stationary relative to it. Even if the skier were moving at the speed of light, the avalanche would still be traveling towards the skier at the speed of light.
Example 3 (Principle of Simultaneity Fails)
Two
Tribes, “A” and “B”
are watching a member of each prepare to compete in a challenge against
one another. A member of each tribe
stands at opposite ends of a trolly car. They
stand equidistant from a flagpole in at the center of the trolly.
At the top of the flag pole there is a light bulb.
Each tribal participant runs at the same speed.
The challenge for the participants is to run to the flagpole when they
see the light bulb flash. If the watching tribes see one start to run before the other
they will go to WAR.
When the trolly is at rest, and the light bulb flashes, both participants begin
to run at the same time, and both reach the flagpole at the same time.
Now the cart is set moving at a constant speed. The light bulb flashes, and the tribes go to war, because they observe the participant on the left before the one on the right. The people on the cart, however, observe that they move at the same time. When the light bulb flashes at a single instant in time, light begins to travel towards each participant. The participants, however, are moving left at a constant velocity, and so in the instant after the light bulb flashes the participant to the left is now closer to where the light source originated and the participant to the left is further from it. Therefore the light reaches the eye of the participant on the left first and he appears to move before the one on the right.
The notion of Simultaneity goes out the window! (As do both tribes futures)