
The universe is expanding faster and is younger than we thought - pzs
https://www.apnews.com/fac50d45a19f4239848b1712cfd22c36
======
acqq
The paper:

[https://arxiv.org/abs/1903.07603](https://arxiv.org/abs/1903.07603)

The disagreement existed for years already, the news is one more value from
those measurements using the "distance ladder" which disagrees with the values
obtained from "CMB and BAO" method. Both groups believe they haven't made any
error in their measurements and can still claim so:

[https://www.forbes.com/sites/startswithabang/2019/05/03/cosm...](https://www.forbes.com/sites/startswithabang/2019/05/03/cosmologys-
biggest-conundrum-is-a-clue-not-a-controversy/)

~~~
mirimir
OK, so these are basically expansion rates measured for different times,
right? And so they're not expected to be the same. But what's problematic is
disagreement with models for how the expansion rate changed over time. Yes?

~~~
acqq
> And so they're not expected to be the same.

Still there was a kind of hope that there would be just one Hubble constant
eventually, resulting from both measurements, that some kind of unexpected
error would be discovered on one (or both) of the sides. But what's happening
is illustrated on the picture subtitled "Modern measurement tensions..." in
the second link, plus the newest result from the Riess' paper: "74.03 +/\-
1.42 km/s/Mpc" with "an uncertainty of 1.91%" which you should imagine
appearing to the right of the picture, with the dot at 74 and much narrower
red bar.

So, looking at that picture again, we have the "blue" and the "red" results
for years already that don't converge and keep doing so, although both
approaches use always more advanced techniques.

But, quoting from the second link:

"It is possible that the ways we measure the expansion rate of the Universe
are actually revealing something novel about the nature of the Universe
itself. Something about the Universe could be changing with time" "Some
options include:

\- our local region of the Universe has unusual properties compared to the
average (which is already disfavored),

\- dark energy is changing in an unexpected fashion over time,

\- gravity behaves differently than we've anticipated on cosmic scales,

\- or there is a new type of field or force permeating the Universe."

"The option of evolving dark energy is of particular interest and importance,
as this is exactly what NASA's future flagship mission for astrophysics,
WFIRST, is being explicitly designed to measure."

But also:

[https://en.wikipedia.org/wiki/Wide_Field_Infrared_Survey_Tel...](https://en.wikipedia.org/wiki/Wide_Field_Infrared_Survey_Telescope)

"The Trump administration's proposed FY2019 budget would terminate WFIRST"

"Again the Trump administration proposed to terminate WFIRST in its FY2020
budget proposal to Congress"

And finally, from the OP article:

"Distinguished University of Chicago astrophysicist Wendy Freedman" "spent
five years looking at different stars than Riess to come up with _a third
calculation of the expansion rate_. They just submitted their work to the same
journal. Freedman wouldn’t reveal her number but said it is between the two
other figures."

~~~
mirimir
Thanks.

I was thinking of a recent post[0] pointing to a NASA press release.[1] And
this part in particular:

> As the team's measurements have become more precise, their calculation of
> the Hubble constant has remained at odds with the expected value derived
> from observations of the early universe's expansion. Those measurements were
> made by Planck, which maps the cosmic microwave background, a relic
> afterglow from 380,000 years after the big bang.

> The measurements have been thoroughly vetted, so astronomers cannot
> currently dismiss the gap between the two results as due to an error in any
> single measurement or method. Both values have been tested multiple ways.

> "This is not just two experiments disagreeing," Riess explained. "We are
> measuring something fundamentally different. One is a measurement of how
> fast the universe is expanding today, as we see it. The other is a
> prediction based on the physics of the early universe and on measurements of
> how fast it ought to be expanding. If these values don't agree, there
> becomes a very strong likelihood that we're missing something in the
> cosmological model that connects the two eras."

0)
[https://news.ycombinator.com/item?id=19768990](https://news.ycombinator.com/item?id=19768990)

1) [https://www.nasa.gov/feature/goddard/2019/mystery-of-the-
uni...](https://www.nasa.gov/feature/goddard/2019/mystery-of-the-universe-s-
expansion-rate-widens-with-new-hubble-data/)

Edit:

> But, quoting from the second link:

ResearchGate doesn't like my IP address. What's the URI?

~~~
acqq
I see. Yes, the two sides are measuring different things. Still note that the
major news there is effectively: "Riess's team reduced the uncertainty in
their Hubble constant value to 1.9% from an earlier estimate of 2.2%."

I fail to see that as something that can bring us to conclude anything exactly
at this moment but that still more different approaches to measurements are
needed. Maybe that Freedman's, or using WFIRST, if it manages to be, or, in
the HN link you give, as ncmncm writes, LIGO:
[https://news.ycombinator.com/item?id=19773731](https://news.ycombinator.com/item?id=19773731)

After more measurements, maybe the theory indeed will have to be more complex
than what just "one and only" Hubble constant could allow. Still, the values
are close enough that even as different as they're now I'm confident that
everything we learned up to now is _mostly_ right. In the cosmological scales
there are maybe some adjustments to come, but anything that affects us is
really good known.

~~~
sanxiyn
I am very excited about Wendy Freedman's number. Her program is called
CCHP(Carnegie-Chicago Hubble Program). The first paper was in 2016:
[https://arxiv.org/abs/1604.01788](https://arxiv.org/abs/1604.01788). The idea
is to use only Population II stars, while Adam Riess's number uses Population
I stars. If the number is in between, that's really cool.

------
everdev
> Using that 74 figure means the universe is somewhere between 12.5 billion
> and 13 billion years old. That’s much younger than the established estimates
> of 13.6 billion to 13.8 billion.

If true, would that mean that the observable universe is smaller than we
thought? And that the distances to distant galaxies might be off as well?

~~~
irjustin
Wow great question, I'm just as confused.

I imagine because the absolute distance is still the same, but how quickly it
got to that position is what's unknown.

The confusion I have is how much is redshift used to determine the distance of
the galaxy vs using standard candle extrapolation?

------
syllable_studio
What if the universe isn't expanding, but rather we're contracting?

~~~
dpark
And the laws of physics are continuously changing with our contraction such
that it’s indistinguishable from the universe expanding?

In that case, there is no difference, so reframing it in term of local
contraction is meaningless.

See also:
[http://www.rogermwilcox.com/darksucker.html](http://www.rogermwilcox.com/darksucker.html)

------
AstralStorm
One day both methods will be looked upon just as the Ptolemeian model of the
solar system is now. Great fit, incorrect model.

