[Moderator's note: I have tried to transform 8-bit characters to
something more legible. Please post only 7-bit printable ASCII
characters. -P.H.]

root wrote:
^^^^
Please post here using your real name.

Can the recent findings of the Space Telescope Institute be used
to revise the age of the universe.

Yes, if those findings were *conclusive*, i.e. would mean that the Hubble
constant *definitely* is greater, then that would mean that our universe
would be slightly younger than previously thought (see below).

However, different from the *wrong* popular-scientific accounts, the HST
estimate merely shows that there might be something fundamental that we do
not yet understand about the universal expansion because different *recent*
measurement methods produced so many different estimates for the Hubble
constant:

https://en.wikipedia.org/wiki/Hubble%27s_law#Observed_values_of_the_Hubble_const ant

Previously one could have thought (and IIUC it had been thought) that
the precision of the experiments were just not so good in the past, but
now we have for the Hubble constant e.g. 67.66±0.42 (km/s)/Mpc by
\_Planck_/ in 2018 (obtained from observing the CMB) and 74.03Â1.42
(km/s)/Mpc by HST in 2019 (obtained from observing cepheids in the LMC).
At some point in time the estimates should converge to one value, but
apparently they do not.

These accounts should be a reliable description of what was really found
and concluded by the HST scientists:

https://www.nasa.gov/feature/goddard/2019/mystery-of-the-universe-s-expansion-rate-widens-with-new-hubble-data

https://www.spacetelescope.org/news/heic1908/

I think that the following much less hysterically written article sums
up and clarifies in laymen terms the
*misconceptions*/*misrepresentations* about the HST result as published
in the rest of the non-scientific media (Business Insider, CBC, Daily
Star, Digital Trends, Heise Newsticker, Science Alert, Sputnik News
etc.) pretty well:

https://gizmodo.com/hubble-measurements-confirm-theres-something-weird-abou-1834339830

What would the estimate of 13.7E9 years

The previous estimate was already 13.796p±0.020 * 10^9 years (Planck
Collaboration 2018: TT,TE,EE+lowE+lensing+BA 68 % limits [1]), which is
"13.8E9 years" when properly rounded.

become if the current rate of acceleration obtained over the entire lifetime?

In that case I will leave the calculation to you, because you *can* do
it Because in that case the age of our universe is easily obtained as
the reciprocal of the Hubble constant:

t = 1/H_0.

[Moderator's note: True if the current RATE of expansion were constant,
but not if the current ACCELERATION were constant. -P.H.]

Note that the Hubble constant is a speed per distance, usually specified
in units of (km/s)/Mpc, which is a length over time over a length, and
therefore has dimensions of 1/[time]. [3]

However, this simple calculation definitely produces the wrong value
(sorry ;-)) because we know from observation that the speed of expansion
was and is not constant over time. Instead, the Hubble constant is
merely the value of the time-dependent Hubble *parameter*

H(t) = a'(t)/a(t)

*now*, at the *current* time:

H(t=t_0) = a'(t=t_0)/a(t=t_0) = H_0,

where a(t) is the scale factor of our universe at time t.

[Moderator's note: Actually, the deceleration and acceleration almost
balance so that the age of the universe is very close to the Hubble
time. In our universe, this happens only near the present epoch. There
have been a couple of papers addressing this coincidence. -P.H.]

For example, if you use the Planck Collaboration's 2015 value of H_0 =
67.31 (km/s)/Mpc (TT+lowP) [1], with 1/H_9 = 14.5 Ga you do NOT obtain
Planck's corresponding t_0 = 13.813 Ga but something considerably
larger.

Therefore I think that obtaining the correct age is not trivial: you
would have to solve an integral of a function over time that involves
the Hubble parameter. That function needs to be designed such that it
fits the actual development of the past expansion speed as obtained from
theory and/or observation of distant objects:

https://en.wikipedia.org/wiki/Universe#/media/File:CMB_Timeline300_no_WMAP.jpg

[Moderator's note: It is an elliptic integral, so somewhat non-trivial
analytically, but well known, and can also be done numerically. -P.H.]

Note in this 2006 depiction of an inflationary LambdaCDM model (based on
WMAP data) the extreme expansion speed in the epoch of inflation (as per
the theory of cosmic inflation) in the first 10â¹ years; then a
moderate, almost linear expansion until our universe was 13 Ã=97 10â¹
years old, followed by an accelerated expansion due to Dark Energy
(Î=9B) since about 770 Ã=97 10ⶠyears ago.

[Moderator's note: Due to the non-ASCII characters, I'm not sure what
was meant, but in any case the age of the universe is essentially
independent of inflation since that lasted only a fraction of a second.
-P.H. There was deceleration until a few billion years ago and since
then acceleration.]

See also (highly recommended):

Tamara M. DAVIS & Charles H. LINEWEAVER (2003). Expanding Confusion:
common misconceptions of cosmological horizons and the superluminal
expansion of the Universe. https://arxiv.org/abs/astro-ph/0310808v2

_______
[1] https://en.wikipedia.org/wiki/Age_of_the_universe#Planck
[2] ESO (2018): Planck 2018 results. VI. Cosmological parameters.
https://arxiv.org/pdf/1807.06209.pdf
[3] Lawrence M. Krauss (2017): Physics Made Easy. Tomasa Terry.
https://youtu.be/bywYBtkfsWA?t=2636 (I recommend the entire talk)
--
PointedEars

Twitter: @PointedEars2
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