matter as we know it atoms stars and galaxies planets and trade rocks and US
this matter
accounts for less than 5% of the known universe about 25% is dark matter and
70% dark energy
both of which are invisible this is kind of strange because it suggests that
everything we experience is really only a tiny fraction of reality but it gets
worse we really have no clue what dark matter and energy are or how they work
we are pretty sure they exist though so what do we know
doesn't matter is the stuff that makes it possible for galaxies to exist when
we calculated why the universe is structured the way it is it quickly
became clear that there's just not enough normal matter the gravity of the
visible matter is not strong enough to form galaxies and complex structures the
stars would will likely be scattered all over the place and not form galaxies so
we know there is something else inside and around them something that doesn't
amid all reflect light something but besides being able to calculate the
existence of dark matter we can see it kind of places with a high concentration
of dark matter bend light passing nearby so we know there's something there that
interacts with gravity right now we have more ideas about what dark energy is not
than what it is we know dark matter is not just clouds of normal matter without
stars because it would emit particles we could detect dark matter is not
antimatter antimatter produces unique emerets when it reacts with normal
matter dark matter is also not made up of black holes very compact objects that
violently affect their surroundings world dark matter seems to be scattered
all over the place basically we only know three things for sure
12 interacts with gravity
3 there is a lot of it dark matter is probably made up of a complicated exotic
particle that doesn't interact with light and matter in a way we expect but
right now we just don't know dark energy is even more strange and mysterious we
can't detect it we can't measure it and we can't taste it but we do see its
effects
very clearly in 1929 edwin hubble examined how the wavelength of light
emitted by distant galaxies shifts towards the red end of the
electromagnetic spectrum as it travels through space he found that fainter more
distant galaxies showed a large degree of redshift closer galaxies not so much
hubbell determined that this was because the universe itself is expanding the red
shift occurs because the wavelengths of light are stretched as the universe
expands more recent discoveries have shown that the expansion of the universe
is accelerating before that it was thought the pull of gravity would cause
the expansion to either slow down or even retract and collapse in on itself
at some point
space doesn't change its properties as it expands there's just more of it
you space is constantly created everywhere
galaxies are tight bound classes of staff held together by gravity so we
don't experience this expansion in our daily lives but we see it everywhere
around us wherever there is empty space in the universe is forming every second
so dark energy seems to be some kind of energy intrinsic to empty space energy
that is stronger than anything else we know that keeps getting stronger as time
passes by empty space has more energy than everything else in the universe
combined we have multiple ideas about what dark energy might be one idea is
that dark energy is not a thing just a property of space empty spaces not
nothing it has its own energy it can generate more space and is quite active
so as the universe expands it could be that just two more and more space
appears to fill the gaps and this leads to a faster expanding universe this idea
is close to an idea that Einstein had back in nineteen seventeen of the
concept of a cosmological constant of faults that counter entered the force of
gravity the only problem is that when we tried to calculate the amount of his
energy the result was so wrong and weird that it only added to the confusion
another idea is that empty space is actually full of temporary virtual
particles that spontaneously and continually form from nothing and then
disappear into nothing again the energy from those particles could be dark
energy all maybe dark energy is an unknown kind of dynamic energy fluid or
field which permeates the entire universe but somehow has the opposite
effect on the universe than normal energy and matter but if it exists we
don't know
how and where or how we could detect it so there are still a lot of questions to
answer our theories about dark matter and dark energy is still just that on
the one hand this is kind of frustrating on the other hand this is frontier
science making it very exciting it shows us that no matter how much we feel we're
on top of things is still very much a piece with smartphones on a tiny fragile
island in space looking into the sky
wondering how our universe works there is so much left to learn and that is
also this video is supported by the Australian Academy of Science which
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