So the speed of light is 300,000km/s. If you have a solid bar of metal floating in space that is 300,000km long, and there is a person standing at either end, and one person pushes the bar... does the person at the other end see the bar move in front of them instantaneously and then see the person at the other end push it one second later? Or, does the bar not move for a second either?
A: The person never sees the bar move because standing in the vacuum of space caused a horrible, violent death.
Seriously though... anybody know the answer?
none of the above. nothing can travel at the speed of light but light itself. i win.
The push would ripple through the bar at the speed of sound, not light, so it's no more complicated than lightning/thunder.
not mikikikikikikik (guest)
none of the above,
The speed of light in the vacuum of free space is an important physical constant usually denoted by the letter c. The SI metre is defined such that the speed of light in a vacuum is exactly 299,792,458 metres per second. (For the value in km/h and other units, see below.)
The speed of light is of fundamental importance in physics. It is the speed of not just light, but of all electromagnetic radiation, as well as gravitational waves and anything having zero rest mass. In Einstein's theory of relativity the speed of light plays the crucial role of a conversion factor between space and time within spacetime. This theory together with the principle of causality requires that no matter or information can travel faster than the speed of light.
The speed of light is so fast that it can often be regarded as essentially instantaneous. However, for short times or large distances, the finite speed of light can be important. For example, in the Global Positioning System (GPS), a GPS receiver measures its distance to satellites based on how long it takes for the radio signal to arrive from the satellite. In astronomy, distances are often measured in light-years, the distance light travels in a year (around ten trillion kilometers).
The speed of light when it passes through a transparent or translucent material medium, like glass or air, is less than its speed in a vacuum. The speed is governed by the refractive index of the medium. In specially-prepared media, the speed can be tiny, or even zero.