# measurement of length in relativity

## Recommended Posts

if length is defined to be nothing but some times a standard length only then why 2 people one moving with respect to the other measures differently the distance between two points?

previous answers i got from people is that it is so for the concept of simultanity differs to the two people. what i dont get is what it's got to do with length?

if we cannot understand two distance to be same if light doesnt reach our eyes simultaneously then what if we are having a continuous source of light? two light rays started at different times may reach our eyes at the same time even when we r moving. how do we know they started the same time?

my question may be stupid its just that i am only a 1st year student in honours course so dont know much. please dont ban me.

##### Share on other sites

Simultaneity is important because it relates to how we measure length. Reality is what we measure it to be, and it depends on your frame of reference.

We don't ban people for asking questions.

##### Share on other sites

well then how we actually measure it can u please explain.

##### Share on other sites

simultaneity - by itself in science means that things that happen simultaneous is not viewed the same by all observers. if you are sitting in a bus, with respect to a person inside it, you are stationary. with respect to a person outside the moving bus, you are moving. with respect to you, that person is moving. but in a vectorially opposite direction. this by itself is the best example of the loss of simultaneity. the reason for this is because, the reference frames of observers are entirely different.

but the speed of light must be a constant in all frames, irrespective of the velocity or other physical properties. so, in order to maintain a universality of the speed of light, the physical dimensions and the time dimensions are distorted. but again the length contraction does not lead to a change in the measurement of the length of that particular object in its frame. that is because it is purely associated with the the moving frame.so to say, in order to maintain a universality of the speed of light, the basic dimensions bend and curve. more so, even gravity succumbs to the constancy of the speed of light.

##### Share on other sites

Since there is already an open thread on a very similar topic I am closing this one.

Go here

##### Share on other sites

This topic is now closed to further replies.
×