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Today's Topics:
1. O/t: The universe is expanding too fast to fit theories:
Hubble tension in crisis (Stephen Loosley)
2. Australia in a 'good position' as AUKUS powers ahead
(Stephen Loosley)
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Message: 1
Date: Mon, 20 Jan 2025 21:30:33 +1030
From: Stephen Loosley <[email protected]>
To: "link" <[email protected]>
Subject: [LINK] O/t: The universe is expanding too fast to fit
theories: Hubble tension in crisis
Message-ID: <[email protected]>
Content-Type: text/plain; charset="UTF-8"
The universe is expanding too fast to fit theories: Hubble tension in crisis
New measurements support faster-than-expected Universe expansion
Date: January 17, 2025
Source: Duke University &
https://www.sciencedaily.com/releases/2025/01/250117161235.htm
Summary:
The Universe really seems to be expanding fast. Too fast, even. A new
measurement confirms what previous -- and highly debated -- results had shown:
The Universe is expanding faster than predicted by theoretical models, and
faster than can be explained by our current understanding of physics. This
discrepancy between model and data became known as the Hubble tension. Now,
results provide even stronger support to the faster rate of expansion. Share:
FULL STORY
The Universe really seems to be expanding fast. Too fast, even.
A new measurement confirms what previous -- and highly debated -- results had
shown: The Universe is expanding faster than predicted by theoretical models,
and faster than can be explained by our current understanding of physics.
This discrepancy between model and data became known as the Hubble tension.
Now, results published in the Astrophysical Journal Letters provide even
stronger support to the faster rate of expansion.
"The tension now turns into a crisis," said Dan Scolnic, who led the research
team.
Determining the expansion rate of the Universe -- known as the Hubble constant
-- has been a major scientific pursuit ever since 1929, when Edwin Hubble first
discovered that the Universe was expanding.
Scolnic, an associate professor of physics at Duke University, explains it as
trying to build the Universe's growth chart: we know what size it had at the
Big Bang, but how did it get to the size it is now?
In his analogy, the Universe's baby picture represents the distant Universe,
the primordial seeds of galaxies. The Universe's current headshot represents
the local Universe, which contains the Milky Way and its neighbors. The
standard model of cosmology is the growth curve connecting the two. The problem
is: things don't connect.
"This is saying, to some respect, that our model of cosmology might be broken,"
said Scolnic.
Measuring the Universe requires a cosmic ladder, which is a succession of
methods used to measure the distances to celestial objects, with each method,
or "rung," relying on the previous for calibration.
The ladder used by Scolnic was created by a separate team using data from the
Dark Energy Spectroscopic Instrument (DESI), which is observing more than
100,000 galaxies every night from its vantage point at the Kitt Peak National
Observatory.
Scolnic recognized that this ladder could be anchored closer to Earth with a
more precise distance to the Coma Cluster, one of the galaxy clusters nearest
to us.
"The DESI collaboration did the really hard part, their ladder was missing the
first rung," said Scolnic. "I knew how to get it, and I knew that that would
give us one of the most precise measurements of the Hubble constant we could
get, so when their paper came out, I dropped absolutely everything and worked
on this non-stop."
To get a precise distance to the Coma cluster, Scolnic and his collaborators,
with funding from the Templeton foundation, used the light curves from 12 Type
Ia supernovae within the cluster. Just like candles lighting a dark path, Type
Ia supernovae have a predictable luminosity that correlates to their distance,
making them reliable objects for distance calculations.
The team arrived at a distance of about 320 million light-years, nearly in the
center of the range of distances reported across 40 years of previous studies
-- a reassuring sign of its accuracy.
"This measurement isn't biased by how we think the Hubble tension story will
end," said Scolnic. "This cluster is in our backyard, it has been measured long
before anyone knew how important it was going to be."
Using this high-precision measurement as a first rung, the team calibrated the
rest of the cosmic distance ladder. They arrived at a value for the Hubble
constant of 76.5 kilometers per second per megaparsec, which essentially means
that the local Universe is expanding 76.5 kilometers per second faster every
3.26 million light-years.
This value matches existing measurements of the expansion rate of the local
Universe.
However, like all of those measurements, it conflicts with measurements of the
Hubble constant using predictions from the distant Universe.
In other words: it matches the Universe's expansion rate as other teams have
recently measured it, but not as our current understanding of physics predicts
it. The longstanding question is: is the flaw in the measurements or in the
models?
Scolnic's team's new results adds tremendous support to the emerging picture
that the root of the Hubble tension lies in the models.
"Over the last decade or so, there's been a lot of re-analysis from the
community to see if my team's original results were correct," said Scolnic,
whose research has consistently challenged the Hubble constant predicted using
the standard model of physics.
"Ultimately, even though we're swapping out so many of the pieces, we all still
get a very similar number. So, for me, this is as good of a confirmation as
it's ever gotten."
"We're at a point where we're pressing really hard against the models we've
been using for two and a half decades, and we're seeing that things aren't
matching up," said Scolnic. "This may be reshaping how we think about the
Universe, and it's exciting! There are still surprises left in cosmology, and
who knows what discoveries will come next?"
This work was conducted with funding from the Templeton Foundation, the
Department of Energy, the David and Lucile Packard Foundation, the Sloan
Foundation, the National Science Foundation and NASA.
--
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Message: 2
Date: Mon, 20 Jan 2025 23:07:43 +1030
From: Stephen Loosley <[email protected]>
To: "link" <[email protected]>
Subject: [LINK] Australia in a 'good position' as AUKUS powers ahead
Message-ID: <[email protected]>
Content-Type: text/plain; charset="UTF-8"
Australia in a 'good position' as AUKUS powers ahead
Story by Tess Ikonomou 6 hours ago
https://www.msn.com/en-au/news/australia/australia-in-a-good-position-as-aukus-powers-ahead/ar-AA1xtIcd
The AUKUS partnership looks safe as key members of the Trump administration
back an agreement that will ease the United States' security burden, experts
say.
Concerns have been raised over the future of the partnership, struck under the
Biden administration, as incoming-president Donald Trump prepares for his
inauguration.
The president-elect is yet to comment publicly on the $368 billion program.
[Photo caption: US President-elect Donald Trump hasn't said anything publicly
yet on the AUKUS deal. (Mick Tsikas/AAP PHOTOS)]
The Congressional Research Service has previously warned of cost blowouts and
delays as the US submarine industrial base comes under increasing pressure.
Australia is set to acquire at least three second-hand Virginia-class
submarines from the US in the early 2030s, with a new class of nuclear-powered
boats to be built for delivery from the 2040s.
Australia is in a "really good position" with people in important positions
backing the partnership, Peter Dean from the University of Sydney's United
States Studies Centre said.
"I'd be very, very surprised if Trump himself didn't continue the AUKUS deal
... and all the indicators are that he will," he told AAP.
"But the caveat for everything with President Trump is he's very material, so
we'll have to wait and see."
[Photo caption: The government is confident AUKUS will be supported by the
Trump administration. (Lukas Coch/AAP PHOTOS)]
AUKUS allowed the transferring of technology to Australia, which would increase
the military capabilities of America's allies, Professor Dean said.
"He (Trump) wants more capable allies who lift more of the burden or and
relieve some of the pressure from the United States," he said.
"One of the key ways of doing that is sharing with countries like Australia,
with close partnerships key technologies."
The president-elect's pick for secretary of state, Marco Rubio, confirmed
support for AUKUS during his Senate confirmation hearings.
Defence Minister Richard Marles said Australia had taken the unprecedented step
of making a "significant contribution" to the American industrial base to
improve production rates.
[Photo caption: "AUKUS is happening and it is on course," Richard Marles said.
(Lukas Coch/AAP PHOTOS)]
"All the agreements that we've asked to be signed and steps to be taken are
being taken. AUKUS is happening and it is on course," he told ABC radio on
Monday.
Foreign Minister Penny Wong is in Washington and will attend Mr Trump's
inauguration ceremony.
She will meet members of the Trump administration, including Senator Rubio,
during her visit.
"We are on a pathway of increasing defence expenditure," she told reporters in
Washington.
--
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