# The age of the universe

divegeester
Science 04 Jun '23 10:09
1. 04 Jun '23 10:091 edit
Given that time is relative to velocity, mass and proximity to mass, how can astrophysicists estimate that the universe is approx 14bn years old using current scales of distance and local time?
2. moonbus
Über-Nerd
04 Jun '23 11:22
@divegeester

We know what the rate of expansion is. So do a thought experiment and reverse the process until the universe shrinks to a singularity; that tells you how long the expansion has been going on.
3. 04 Jun '23 15:07
@moonbus said
@divegeester

We know what the rate of expansion is. So do a thought experiment and reverse the process until the universe shrinks to a singularity; that tells you how long the expansion has been going on.
But…

What I posted about relatively, mass, etc etc
4. moonbus
Über-Nerd
04 Jun '23 17:07
@divegeester said
But…

What I posted about relatively, mass, etc etc
Actually, there are at last two methods of estimating the age of the universe:

https://map.gsfc.nasa.gov/universe/uni_age.html

This help ?
5. sonhouse
Fast and Curious
05 Jun '23 04:21
@moonbus
What do you think of the problem turned up by James Webb V Hubble about the expansion of the universe?

https://www.nationalgeographic.com/science/article/the-universe-is-expanding-faster-than-it-should-be
6. moonbus
Über-Nerd
05 Jun '23 05:241 edit
@sonhouse

It is very exciting news. It means we still have some work to do to understand the universe we live in. My admittedly layman's attitude to discrepancies in measurements is that, given that we're living in an explosion, it should not surprise us that the universe is not expanding uniformly in all directions. It is only to be expected that there would bits expanding faster than other bits, giving rise to regional differences in measurement. Think of the universe having 'lumps' -- not too implausible, really.
7. 05 Jun '23 10:11
@moonbus said
Actually, there are at last two methods of estimating the age of the universe:

https://map.gsfc.nasa.gov/universe/uni_age.html

This help ?
Why not just discuss my OP instead of lazily posting links to NASA editorials.
8. 05 Jun '23 10:34
@divegeester

https://www.redhotpawn.com/forum/science/how-old-is-the-universe.196645
9. 05 Jun '23 10:38
@moonbus said
@divegeester

We know what the rate of expansion is. So do a thought experiment and reverse the process until the universe shrinks to a singularity; that tells you how long the expansion has been going on.

https://www.forbes.com/sites/startswithabang/2018/07/27/there-was-no-big-bang-singularity/
10. moonbus
Über-Nerd
05 Jun '23 12:01
@metal-brain said

https://www.forbes.com/sites/startswithabang/2018/07/27/there-was-no-big-bang-singularity/
Yup. That’s how science works. Keep looking for better evidence.
11. moonbus
Über-Nerd
05 Jun '23 13:11
@divegeester said
Why not just discuss my OP instead of lazily posting links to NASA editorials.
I find the most interesting portion of the history of the universe to be the invisible part, the horizon past which our instruments cannot measure, when the very early universe was too hot to propagate photons. This portion is harder to estimate because we have only theory, not observable evidence.
12. 05 Jun '23 15:15
@metal-brain said

https://www.forbes.com/sites/startswithabang/2018/07/27/there-was-no-big-bang-singularity/
13. 05 Jun '23 15:19
@moonbus said
I find the most interesting portion of the history of the universe to be the invisible part, the horizon past which our instruments cannot measure, when the very early universe was too hot to propagate photons. This portion is harder to estimate because we have only theory, not observable evidence.
Sonhouse was correct when he was referring to the universe have lumps, as I understand it anyway.

As the universe expanded the matter/mass accelerated in all directions stretching out spacetime. My question in my OP relates to this expansion which wasn’t uniform in terms of the destruction of mass and therefore time would not have been uniform and in a constant state of relativistic change.

So I’m posing the question of how would this dynamic change our perception and measurement of the universes age when we are only looking at it from our local perspective.
14. moonbus
Über-Nerd
05 Jun '23 21:57
@divegeester said
Sonhouse was correct when he was referring to the universe have lumps, as I understand it anyway.

As the universe expanded the matter/mass accelerated in all directions stretching out spacetime. My question in my OP relates to this expansion which wasn’t uniform in terms of the destruction of mass and therefore time would not have been uniform and in a constant state ...[text shortened]... tion and measurement of the universes age when we are only looking at it from our local perspective.
I don't know what it would mean for time to be not uniform. Supposing 'time' went sometimes faster or slower, all processes 'in' time would also go faster and slower, including any clocks attempting to measure this -- so everything would still be 'in synch' and no fluctuation would be noticeable.

I don't see any problem with there being 'lumps' in the distribution of matter. There are measurable variances in the cosmic background radiation level, too. My guess is, these average out, in calculating the age of the universe. But that's just a guess. I'm not familiar with the equations astronomers are actually using to calculate the age of the universe.
15. 06 Jun '23 05:00
@moonbus said
Supposing 'time' went sometimes faster or slower, all processes 'in' time would also go faster and slower, including any clocks attempting to measure this -- so everything would still be 'in synch' and no fluctuation would be noticeable.
This is what happens and it would have an impact.

For example if person A was travelling at close to light speed for one month relative to and away from person B who was stationary, and then person A returned at the same speed for another month. Then person A would age hardly at all, while person B would have aged 2 months. This is true for all matter.

Also if a person travelled to the edge of the event horizon of a black hole as they approached time would be increasingly slowed down for them relative to an observer from a distant place. Eventually the mass of the black hole would slow time for the traveller so much that the observer would see them come to a stop at the event horizon as their respective time experiences were so different.

So, back to my OP. In the early universe we have no idea of how time was impacted by the intense almost infinite mass. We also have no idea how time is impacted by the incredible speed at which the distant universe is expanding; expanding so fast that the fabric of space is expanding faster than light can traverse it, hence the limit of the observable universe”. Eventually if person C lived long enough then they would look into the night sky and see nothing at all.