Can the recent findings of the Space Telescope Institute be used
to revise the age of the universe. What would the estimate
of 13.7E9 years become if the current rate of acceleration obtained
over the entire lifetime?
Can the recent findings of the Space Telescope Institute be used
to revise the age of the universe.
What would the estimate of 13.7E9 years
become if the current rate of acceleration obtained over the entire lifetime?
Can the recent findings of the Space Telescope Institute be used
to revise the age of the universe. What would the estimate
of 13.7E9 years become if the current rate of acceleration obtained
over the entire lifetime?
root wrote:
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.
| 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.
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 10^9 years; then a
moderate, almost linear expansion until our universe was 13 * 10^9
years old, followed by an accelerated expansion due to Dark Energy
(Lambda) since about 770 * 10^6 years ago.
| 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.
Thomas 'PointedEars' Lahn wrote:
root wrote:
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.
The OP was not even talking about the `current acceleration', but the `current rate of acceleration'.
| 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.
I think I have shown here that the moderator's statement is not true.
A difference of several hundred million years is NOT "very close".
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 10^9 years; then a
moderate, almost linear expansion until our universe was 13 * 10^9
years old, followed by an accelerated expansion due to Dark Energy
(Lambda) since about 770 * 10^6 years ago.
| 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.
So the image I referred to is imprecise in that regard?
| 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.
I think I have shown here that the moderator's statement is not true.
A difference of several hundred million years is NOT "very close".
There are at least two papers on arXiv on this topic, one by Geraint
Lewis, Pim van Orschok (not sure of the spelling), and possibly more
authors, and one by Bob Kirshner and a co-author. The degree of
coincidence is independent of the Hubble constant, but of course depends
on the values of lambda and Omega used. (The second paper has an
obvious title; the first is also about something else, but the title
isn't obvious.) I can't check now but they can probably be found at arXiv.org in less than a minute.
The main point of the Space Telescope Institute work https://arxiv.org/abs/1903.07603
is that 4.4 sigma discrepancy between Planck Ho and STI Ho is not
readily attributable to an error in any one source or measurement,
increasing the odds that it results from a cosmological feature beyond LambdaCDM'.
In article <u6mdnbzd2qfIWFTBnZ2dnUU7-YnNnZ2d@giganews.com>,=20
"Richard D. Saam" <rdsaam@att.net> writes:
The main point of the Space Telescope Institute work https://arxiv.org/abs/1903.07603
is that 4.4 sigma discrepancy between Planck Ho and STI Ho is not=20 readily attributable to an error in any one source or measurement,=20 increasing the odds that it results from a cosmological feature beyond=
LambdaCDM'.=20
Indeed. Whatever it is, it doesn't seem to be statistics.
The preprint (linked above) gives references to other work on the CMB
and BAO, which methods give the Hubble-Lemaitre parameter at high
redshift, i.e., early in the history of the Universe. A simple
summary is that dark energy appears to have increased over
cosmological time. =20
Fig 4 of the preprint gives some ideas of why
that might have happened. Another possibility, of course, is that
there is some unrecognized systematic error in one of the
measurements. The local H_0 looks pretty solid to me. I know less
about the early H but can't help wondering about the calculated
sound-wave distances, which depend on baryonic physics.
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