
The universe may be a billion years younger than we thought - okket
https://www.nbcnews.com/mach/science/universe-may-be-billion-years-younger-we-thought-scientists-are-ncna1005541
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btilly
There is actually a third way to bound the age of the universe. And that is to
say that it must be older than the oldest known stars. In particular, older
than
[https://en.wikipedia.org/wiki/HD_140283](https://en.wikipedia.org/wiki/HD_140283).

This star is (barely) compatible with the Plank readings. It is nowhere near a
fit with the new figures. So while a lot of science has to be done to
reconcile the methodologies, I'm betting that the universe doesn't wind up
being a billion years younger than we thought.

~~~
sfifs
If you read the paper, the age calculation reads like assumption upon
assumption upon assumption upon assumption. The distance measurement is
remarkable though.

~~~
btilly
_Every_ age calculation in astronomy reads like that. Distance calculations as
well.

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astro123
The full story is actually (I think) more interesting than the headline
suggests.

Really what we have here are two methods of calculating the age of the
universe that disagree. And we are getting to a stage where the disagreement
(or "tension") is fairly statistically significant (3 or 4 sigma if I remember
correctly). But, if LambdaCDM is the correct model for the universe these two
methods should give the same age and so the fact that they are different
implies that there is more to the universe (new physics!) than LambdaCDM. This
is very exciting (and imo much more exciting than a 10% change of the age of
the universe)!

Of course, both sets of measurements are fantastically hard to make and so
there is a chance that this disagreement is just a result of a systematic that
hasn't been properly understood/controlled for... But people are starting to
think this might be real.

Here's a readable summary of what's going on:
[https://astrobites.org/2016/08/22/the-trouble-
with-h0/](https://astrobites.org/2016/08/22/the-trouble-with-h0/)

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tomcam
I swear when the weather’s good it doesn’t look a day over 9 billion around
here.

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beaconfield
This is a really cool story. Science FTW! We have new evidence and people are
starting to adjust their frame of mind and thinking in regards to the new
evidence. Hopefully they can prove their hypothesis and we'll have a better
idea of the actual age of the universe.

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sunstone
I would like to see a scattergram of the universe's estimated age over the
past one hundred years just to see if we're starting to converge yet or not.

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earthboundkid
MOND, MOND, MOND…

~~~
earthboundkid
I can believe in dark matter.

I can believe in dark energy.

I cannot believe in both…

MOND, MOND, MOND…

~~~
Tomminn
MOND doesn't actually get rid of dark matter, it just means you only need ~20%
as much of it. If it did fix dark matter it'd very possibly be the more
popular theory. The issue is that galaxies-- according to the dark matter
paradigm-- don't have a precisely predictable amount of dark matter. There are
galaxies that seem to have vastly different quantities of dark matter than
other galaxies that despite the fact that their ordinary mass distribution
looks very similar. That is, different galaxies need different amounts of
correction from Newtonian Dynamics in ways that are seemingly random, and
therefore cannot be incorporated into MOND. So you still need some dark matter
to fix this problem.

~~~
DougN7
This has always felt a little wrong to my layman mind. It’s like saying 4+2=7.
Oh it doesn’t match? Well, invent some magic stuff to fix the difference
(4+2+magic=7) so we don’t have to change what we believe. I guess I don’t
understand why it’s not easier to doubt what we think we know than invent
something we don’t have evidence for. Is dark matter’s existence a settled
thing?

~~~
AnimalMuppet
I am also a layman, but I'll take a stab at it.

Here's a galaxy with a certain amount of mass, distributed a certain way. It
has a certain rotational velocity (as a function of radius from the center).

Here's a different galaxy that has just about the same mass and mass
distribution, but it has a different rotational velocity. That leaves a very
few options:

\- Our measurements are wrong.

\- Rotational velocity is not a function of mass.

\- Or, there's more mass than we can see.

People have carefully checked the first, but it's still possible. The second
seems really weird: Rotational velocity depends on mass plus the roll of
2d6?!? That leaves dark matter as the explanation that seems the most
reasonable.

~~~
DougN7
Aren’t the first and third the same thing - we didn’t measure it all?

To just invent something that can’t be explained to make us feel better sounds
a whole lot like religion.

[edit] Also, thank you for your reply. It helps

~~~
AnimalMuppet
One is, either we didn't correctly measure the mass (which we measure by the
light emitted), _or_ we didn't measure the rotational velocity correctly
(which we measure by doppler differences between the different sides of the
galaxy).

The third is that there is mass that doesn't emit light at all. (I think it's
a bit stronger than that. I think that they think that it doesn't interact
with light at all, not just not emit it. But I forget how they think they know
that, and I'm not certain that they think they know it at all.)

> To just invent something that can’t be explained to make us feel better
> sounds a whole lot like religion.

They don't invent it to make themselves feel better. They invent it so their
equations work. (Of course, they feel better when their equations work...)

~~~
dogma1138
Dark matter doesn’t interact with any of the forces other than gravity and
possibly the weak force.

Not interacting with the electromagnetic force is the same thing as not
emitting light.

But this also means that DM cannot be cold baryonic matter.

MOND or any other modifications of Newtonian Gravity or GR aren’t random.

In the case of MOND (and TEVES) Gravity is modified but it’s modified in a
manner that is consistent with both macro and micro observations it’s not
adding a random dice throw.

The reason why people went after MOND and the rest is that Newtonian Gravity
is surprisingly accurate even without using PPN.

Now the big problem with MOND and most of the other modifications is the speed
of gravitational waves that pretty much shut down much of the discussion.

That said I’m not entirely sure they had the wrong idea at this point I think
it’s more likely we don’t understand something about gravity or space time
than there is a new class of matter out there.

That said the fact that we have both found clusters which apparently more dark
matter than usual and those which seem to completely lack DM is still a good
reason to continue searching for DM.

However I really don’t like how MOND proponents were treated especially pre-
LIGO.

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rightbyte
It's quite silly being surprised by inaccuracies in measuring the age of the
universe by dead reckoning from some "ether" background radiation.

"More shocking, Hubble found that the farther away the galaxies are, the
faster they're moving apart."

Like really? Shocking? Relative fast moving galaxies are further away than the
ones with slow relative velocity by the time of measurement?

I feel the hunt for astonishing publications are to blame for all the
hullabaloo.

~~~
jtbayly
That's not what's happening according to the article:

"Given the stakes, everyone involved is checking and rechecking their results
for possible sources of error. Increasingly, though, it looks like the problem
lies not with the observations but with the theories of cosmology that
underpin them. If those theories are wrong or incomplete, the interpretation
of the Planck readings will be flawed, too."

~~~
rightbyte
Ye, the reevaluation of prior result is a sign of good science and should be
of greater prestige (i.e. more grant money) among researchers. There is a
science wide bias for interesting results.

The same article also writes "Then came an unexpected turn of events" when
another researcher disagrees to some degree, which is in no way unexpected.

