hello there , now excuse me to those to whom this looks like the questions you have hard a thousand times before.(adsbygoogle = window.adsbygoogle || []).push({});

Now I understand how we calculate the speed of light in vacuum and no doubt we can do that under laboratory conditions etc.

Light bending in gravitational fields is also understood.

Now I understand that we have other ways of telling the approximate age of the universe , but here I want to ask about the one which involves distant stars and objects and light traveling from them.

Now it is clear that as both the observer (earth) and the distant star move ahead in time simultaneously , when the observer from earth suddenly wants to take a look at the distant star he sees the star as it was when the light, that now has came to the observers "eye", left the distant star.So from that we take to calculate how long the light has traveled from the distant star hence we get the age.Now when we look the furthest possible we can see , we say that this light that we saw has traveled that and that years and "voula" we get the age of the universe.

Now after all that I just said I have a hard time understanding how can we calculate and say the time it took for the light to come to us if we don't know the distance it has traveled ? I'm not a mathematics genius but I can tell that just by knowing the speed of a car you can't tell how long it has been traveling at that or other speeds.

The difficulty here for me is that we know the light speed in vacuum and we can measure that , we also can tell the frequency change due to red or blue shift (gravity) but how can we tell how far hence old is the light that has come to us if the photons that hit our "eye" are just that photons emitted from a source a "while" ago but they don't tell about themselves nothing more than just the speed and frequency of them and speaking in big terms the "picture" they show us.

maybe I'm missing out a stupid little but very important thing here so help me out.?

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# Speed of light , age, etc.

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