# Reply to post: What is speed relative to?

### Voyager 1 fires thrusters last used in 1980 – and they worked!

#### What is speed relative to?

Question and one that used to wind my physics teachers up. What pray is the speed relative to. To have a given speed then it must be able to be compared with something that relative to the moving object is stationary. So please pray tell me in the universe which object is stationary. For example, if a gun on the satellite was fired say in the direction of travel at 700mph, is the bullet going at the speed of the satellite +700 or is the bullet going to come out of the back of the rifle. it cannot go backwards it must go forwards so if light was projected back to earth would it be at what speed.

You see the radio waves which travel at the speed of light get to the unit and come back, therefore in space there must be a "stationary" whatever that may be. A point in time, a geographic point. There now some body explain that. No person not even serious boffins have been able to explain it.

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