If gravitational field make clocks run slow, how can we know the true age of the universe?

Question

If time is measured differently in different frames, how can the Universe have only one age? how certain is the universe age as 13.8 billion years old.?

Answer 1

This is a very good question!

It is true that time intervals are measured differently in different frames. But when doing cosmology, there are frames called 'comoving frames' that are used for time measurements. Essentially, a comoving frame is one that is at rest with respect to the average motion in its neighborhood. Galaxies are good approximations to comoving observers. Anyway, in general relativity, all comoving observers will record the same time intervals and so will agree as to the age of the universe. This happens even though the galaxies are 'moving' with respect to each other. The geometry of spacetime counteracts the special relativity Lorentz laws. So, when we say that the universe is 13.8 billion years old, we say that for comoving frames.

Answer 2

Slow or fast is not absolute. It depends on your set of coordinates. Pls. remember the example of a train whistle frequency when the train is approaching or leaving a station.
There are other clues, for example the decay of radioactive materials, which can give us the age if not of the whole universe at least the age of some earthly minerals.
I understand this is not a complete answer. I am not an expert.
The astronomers may have other means to calculate the age of the universe, such as the apparent speed of galaxies and their distance from the Big Bang origin.

Answer 3

just because gravity increses friction on a clocks moving parts causing it to slow down does not mean time is slower and mag feilds also change current flow in electric clocks as well they may also effect biological clocks. also the universe is not 13.8 billion years old that time fram is not long enough to suport the evidence of galixy collisions that we can see in the sky in a big bang all matter is going out from one point of origin. a galixy collision demonstrats two different points of origin unless you think one galixy just did a 180 degree u turn as two colide with another. that one u turn would probably take billions of billions of years to compleate and require a great gravitational effect to change the course of its mass and add to that the distance away that this collision occured is billions of light years. all of these factors add up to a time fram well beyond 13.8 billion years.

Answer 4

That was a very interesting question. Remember that time itself is relative, so the 13.8 billion years is relative to us Earthlings, because we took the readings. Some other observer who was moving, let's pretend, at high speed relative to us would see the colours (i.e. Doppler shifts) of the galaxies differently than we would. He would conclude different speeds for them, and, extrapolating back to the beginning of time, might conclude that the universe is a different number of years old than our figure.

Answer 5

We don't know the true age of the universe. Astronomers are constantly revising their estimates as new technology provides new information, and there are different opinions on the likely age. Current beliefs vary from 12billion to 20billion years

Answer 6

1.
The time depends from gravitational fields.
Every planets have own gravitational fields,
own time.
2.
Since most of the Universe is empty.
So in the Empty Universe / Vacuum there is not time.
3.
Question:
How from Empty Universe / Vacuum
the all Existence created?
======================
http://www.socratus.com

Answer 7

Since most of the universe is empty, unless you are near a massive object, there is very little distortion of time because of the lack of strong gravitational fields.

Answer 8

I imagine time is given as a constant as I will be set here on earth.
And lets be honest most things in astronomy are inferred so they are only guessing anyway

Answer 9

If you go to this USGS web site, it has a detailed description of how time has been kept and recorded withing the earth itself.

Hope this helps a little.

http://pubs.usgs.gov/gip/geotime/age.html