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For thousands of years, people have been trying
to understand why the universe looks the way it does.
Why, because we’re humans and that’s what we do.
In the last several decades, one way scientists
have been approaching this question
is by studying dark matter.
This is a mysterious substance that’s needed
to explain the observed distributions
and motions of galaxies.
We can’t see it, smell it, or detect it
with any of the techniques available to us,
but whatever it is, evidence suggests it exerts
a gravitational force on visible matter.
Evidence also suggests that there’s a lot
of it,
and that it might make up about 80% of the universe’s mass.
Of course, if we can’t actually detect this
stuff, it’s kind of hard to know anything beyond that,
like where dark matter came from,
for example.
But a new study, published last week in Physical
Review Letters,
may have just opened the door to a startling possibility.
It provides mathematical evidence suggesting
that dark matter might be so hard to find
because it formed before the Big Bang.
Alright, if that last sentence made you freak
out, it’s fine.
I understand.
This hypothesis doesn’t break everything
you thought you knew about the Big Bang:
It just depends on your definition of that term.
Normally, we talk about the Big Bang as the
very beginning of the universe.
But some scientists actually use a different
definition.
This paper treats the Big Bang as the beginning
of the expanding universe as we know it,
the time where things started to cool down after
a period of rapid growth.
That growth period was called cosmic inflation,
and that’s when this paper argues that dark matter may have formed.
During this short period, the universe expanded
much faster than it does today,
like, trillions of trillions of times faster.
It was an alien, quantum world,
so it’s not weird to think that something like dark matter could have formed during this time.
Besides, some scientists already believe that
certain particles called scalars
might have formed during cosmic inflation.
Scalar particles have a pretty technical definition,
they’re bosons with a zero spin,
if that means anything to you.
But the important thing to know here is that
they can also be notoriously difficult to detect.
In fact, the only fundamental one we’ve
managed to pin down with any certainty is
the famous Higgs Boson, and that took decades.
So if dark matter formed along with scalars,
or is made of scalar particles, well,
it’s not surprising we haven’t been able to find
it.
Now, it is worth noting that this idea about
dark matter isn’t entirely new.
But for the first time, this study has done
the math to show that it could be true.
This work already fits with what we know dark
matter can and can’t be,
based on previous measurements.
It also gives parameters that could help us
test the new model to find out more about dark matter
with astronomical observations,
rather than with particle physics.
That investigation will likely take a while.
But in the meantime, we at least have a framework
for a testable hypothesis,
something that is rare in the speculation-heavy field of
dark matter physics.
It’s big, complicated research, but in the
end, if this hypothesis is confirmed,
it could launch us into an entirely new era of dark
matter research.
Of course, dark matter isn’t the only thing
in the universe we’re still not sure about.
I don’t even know what I had for breakfast
this morning.
There are all kinds of objects keeping their
secrets close to their chests,
like my avocado toast and like neutron stars.
Neutron stars are small, incredibly dense,
rapidly-rotating objects.
They’re made almost entirely of neutrons,
and they form after a star explodes at the end of its life.
Most neutron stars spin many times per second,
but occasionally they glitch, and their rotation can speed up even more.
In a study published Monday in Nature Astronomy,
scientists have used a glitch like this to study the heart of a neutron star for the first time.
And while they were able to confirm some previous
ideas, they also uncovered a shiny new mystery.
The team’s observations focused on the Vela
pulsar,
a neutron star a thousand light-years away that’s known to glitch about once every three years.
During its last glitch in 2016, a radio telescope
in Australia took some great data,
and in this new study, the authors analyzed that
data to figure out what was going on
in the star’s interior.
According to their results, the star is composed
of a rigid crust that surrounds layers
of spinning, superfluid neutrons.
These neutrons so cold and dense that they
can keep flowing without losing any kinetic energy.
But sometimes, complex processes can cause
that flow to change, and that leads to a glitch.
First, the outermost layer of superfluid neutrons
starts to move outwards,
where it hits the star’s rigid outer crust and causes it to
spin faster.
Then, the innermost layer of superfluid neutrons
moves outward, too.
It catches up with the first layer and ultimately
causes the star to slow down again.
Although this kind of behavior has been predicted,
these analyses were able to confirm it for the first time,
but that wasn’t the only
important thing they did.
The data also turned up another surprising
phenomenon:
Before the glitch, the star’s rotation actually appeared to slow down.
Scientists have never seen something like
this in a neutron star before,
and the researchers admit that right now, they have no idea why it happens.
It’s something they’re going to have to
keep checking out,
once they’re done celebrating these new findings, at least.
Because regardless of what comes next,
this study has given us amazing insight into a mysterious cosmic object.
And with every paper like this, we’re getting
a better understanding
of how our universe works as a whole.
Which, honestly, is pretty amazing.
So whether it’s from new data or new hypotheses,
these papers have opened doors to new research paths.
And it’s going to be exciting to see where they
lead!
As always, we’ll keep you updated.
Thanks for watching this episode of SciShow
Space News!
If you enjoyed this, there’s a good chance
you would also like our podcast.
It’s called SciShow Tangents.
It’s part science podcast, part game show,
and just generally a very good time.
I host it along with three really smart, funny
people,
and I always learn something new and ridiculous.
You can listen wherever you get your podcasts.
And if you want to ask us a question for our
next episode,
you can find us on Twitter 
@SciShowTangents.
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