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matter as we know it atoms stars and
galaxies planets and trade rocks and US

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this matter

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accounts for less than 5% of the known
universe about 25% is dark matter and

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70% dark energy

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both of which are invisible this is kind
of strange because it suggests that

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everything we experience is really only
a tiny fraction of reality but it gets

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worse we really have no clue what dark
matter and energy are or how they work

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we are pretty sure they exist though so
what do we know

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doesn't matter is the stuff that makes
it possible for galaxies to exist when

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we calculated why the universe is
structured the way it is it quickly

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became clear that there's just not
enough normal matter the gravity of the

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visible matter is not strong enough to
form galaxies and complex structures the

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stars would will likely be scattered all
over the place and not form galaxies so

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we know there is something else inside
and around them something that doesn't

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amid all reflect light something but
besides being able to calculate the

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existence of dark matter we can see it
kind of places with a high concentration

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of dark matter bend light passing nearby
so we know there's something there that

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interacts with gravity right now we have
more ideas about what dark energy is not

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than what it is we know dark matter is
not just clouds of normal matter without

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stars because it would emit particles we
could detect dark matter is not

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antimatter antimatter produces unique
emerets when it reacts with normal

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matter dark matter is also not made up
of black holes very compact objects that

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violently affect their surroundings
world dark matter seems to be scattered

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all over the place basically we only
know three things for sure

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12 interacts with gravity

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3 there is a lot of it dark matter is
probably made up of a complicated exotic

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particle that doesn't interact with
light and matter in a way we expect but

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right now we just don't know dark energy
is even more strange and mysterious we

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can't detect it we can't measure it and
we can't taste it but we do see its

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effects

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very clearly in 1929 edwin hubble
examined how the wavelength of light

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emitted by distant galaxies shifts
towards the red end of the

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electromagnetic spectrum as it travels
through space he found that fainter more

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distant galaxies showed a large degree
of redshift closer galaxies not so much

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hubbell determined that this was because
the universe itself is expanding the red

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shift occurs because the wavelengths of
light are stretched as the universe

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expands more recent discoveries have
shown that the expansion of the universe

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is accelerating before that it was
thought the pull of gravity would cause

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the expansion to either slow down or
even retract and collapse in on itself

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at some point

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space doesn't change its properties as
it expands there's just more of it

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you space is constantly created
everywhere

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galaxies are tight bound classes of
staff held together by gravity so we

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don't experience this expansion in our
daily lives but we see it everywhere

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around us wherever there is empty space
in the universe is forming every second

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so dark energy seems to be some kind of
energy intrinsic to empty space energy

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that is stronger than anything else we
know that keeps getting stronger as time

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passes by empty space has more energy
than everything else in the universe

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combined we have multiple ideas about
what dark energy might be one idea is

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that dark energy is not a thing just a
property of space empty spaces not

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nothing it has its own energy it can
generate more space and is quite active

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00:04:18,289 --> 00:04:22,979
so as the universe expands it could be
that just two more and more space

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appears to fill the gaps and this leads
to a faster expanding universe this idea

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is close to an idea that Einstein had
back in nineteen seventeen of the

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concept of a cosmological constant of
faults that counter entered the force of

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gravity the only problem is that when we
tried to calculate the amount of his

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energy the result was so wrong and weird
that it only added to the confusion

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another idea is that empty space is
actually full of temporary virtual

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particles that spontaneously and
continually form from nothing and then

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disappear into nothing again the energy
from those particles could be dark

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00:05:01,389 --> 00:05:06,570
energy all maybe dark energy is an
unknown kind of dynamic energy fluid or

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field which permeates the entire
universe but somehow has the opposite

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effect on the universe than normal
energy and matter but if it exists we

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don't know

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how and where or how we could detect it
so there are still a lot of questions to

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answer our theories about dark matter
and dark energy is still just that on

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the one hand this is kind of frustrating
on the other hand this is frontier

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science making it very exciting it shows
us that no matter how much we feel we're

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on top of things is still very much a
piece with smartphones on a tiny fragile

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island in space looking into the sky

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wondering how our universe works there
is so much left to learn and that is

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also this video is supported by the
Australian Academy of Science which

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00:05:55,610 --> 00:06:00,310
promotes and supports excellence in
science learn more about this topic and

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00:06:00,310 --> 00:06:05,470
others liked it and move at all da tu it
was a blast to work with them so go

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check out their site

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