This is my first post here. I have been trying to understand the logic behind the exclaimation that time is relative. To this moment I have failed. I guess I need some additional information in order to do this so I ask for your help. As it looks to me now Einstein has merely proven that relativity of time is a possibility, but not a fact. ---------------- 1. The speed at which physical objects operate is affected by circumstances. 2. Time is measured by the speed at witch some defining physical objects operate. - - - 3. Therefor time can be (and is) affected by circumstances. 4. Time is relative. -------------------- I think that 3 and 4 can not be derived from 1 and 2. Even if we accept that the measuring of time is relative, that doesn´t necessarily mean time itself is relative - does it? Time could very well be universal and constantly the same even though all time measuring devices start to behave differently. A crude example would be this. 1. Temperature affects steel rods. 2. The distance from Paris to Calais can be measured by using steel rods. - - - 3. Therefor temperature can affect the measuring of the distance between Paris and Calais. 4. The distance between Paris and Calais is relative. How is relativity of time different from this fallacy? Couldn't you deny that time was relative simply by saying that science has showed that clock can't measure time? (even though I doubt you had to go so far).