| What is the universe made of?|
|Question Date: 2018-01-09|
Great question! Keep thinking big! Most
people don't ask important questions like
The simple answer to your question is that
the universe is made up of three things: 5%
normal matter, 27% dark matter, and 68% dark
energy. The not-so-simple answer to your
question is...well, not so simple! So let's
Normal matter is anything that has mass and
takes up space by having volume. The stars in
the sky, our planet Earth, and even you are made
up of matter! To be specific, you are made up
of around 7 x 1027 atoms all vibrating
with electrons, neutrons, and protons flying
around inside of you! Despite the massive
number of atoms that make up just you alone,
normal matter only makes up a mere 5% of the
stuff in our universe.
Dark matter is...not as simple to
explain. Why? Well, honestly because
not even the top scientists fully understand what
it is. So they learn about it, by identifying what
it isn't. Unlike normal matter (for example, you),
dark matter neither reflects nor emits
light...so how do we know it's there?
It began in the 1930s as astronomers were
asking the same question that you asked
"what is the universe made of?" In
the process, they found that the galaxies in our
universe are spinning very fast...too fast for
them to be held together by the gravity from
normal matter alone! Imagine that the galaxies are
like people riding a merry-go-round that is
spinning at 300 miles an hour. Even if they have
good grips and strong arms...they should have been
ripped from their seats by now! So there must be
another force keeping them on this imaginary
Thinking the same thing, in 1933 a Swiss
astronomer named Fritz Zwicky suggested
that the universe can't only be made of normal
He called it dark matter because it does not
reflect or emit light, but it most certainly
is there. Today, all we know is that dark
matter makes up about 27% of the universe, and
that it is not like atoms...it's more like a
medium or a substance.
Dark energy is the last thing on our
list, but also the biggest. Dark energy makes
up about 68% of our universe, and despite how
much of it there is...we know so little about it!
To grasp it, one proposed definition is that
dark energy is the energy that comes from empty
space in the universe. It's not necessarily a
thing, but rather a property of space. Just
like dark matter, it is not made up of particles
and while we can't observe it directly, we know
it exists because we have observed how it bends
light coming from distant stars.
Hopefully this sheds some light on what the
universe is made of!
This is actually a very interesting question.
Though we already have a good amount of knowledge
about our universe, there are still a lot of
unanswered questions. I will talk about what we
know so far.
To talk about what our universe is made of,
I'd like to offer my answers in two directions.
The general sense is that universe include all
the space, time, energy, etc.
First, we can talk about our universe in a
relative large scale, ignoring the details. In
that sense, our universe includes galaxies,
planets, stars, black holes, etc. There are also a
large part of dark matter and dark energies
which are less known to us. In this picture, our
universe is filled with galaxies (includes
planets, stars, etc.) in space, running with time,
and don't forget the dark matter and dark energy.
Second, we can talk about our universe in terms
of the basic particles, such as leptons
(example electrons), hardons, and photons.
Those basic particles will form the matter we
know, from electrons, neutrons, protons, to atoms,
to molecules, to compounds, and so on. Then it is
more familiar to you now. Since those compounds
and matter will form our Earth, the moon, our Sun,
our solar system, etc. Here I want to emphasize
again: those dark matter and dark energy are
still little known. In this picture, our
universe is made of those elementary particles and
also include dark matter and dark energy.
The universe is everything, and so is made of
About 60% of the energy in the universe is
something called "dark energy" ("dark" meaning
that we don't understand it and can't see it,
not that it's evil or something like that). It
seems to exert a repulsive gravity-like
force that keeps the universe expanding.
36% of the energy is "dark matter" (same
meaning of the word "dark"). This seems to be
mysterious particles that have mass and gravity as
we understand them, but don't interact with the
rest of the universe except via their gravity (at
least, not that we've ever seen).
The remaining 4% contains all of the atoms
that we are familiar with. Of the atoms in
the universe, about 90% are hydrogen, 9% are
helium, 0.6% are oxygen, 0.3% are carbon, and
everything else is in trace amounts.
Some of the universe is made up of the same
atoms which make up the world around us. These
atoms are listed in the periodic table, and they
can be combined into the various molecules and
compounds in everything we see, like dirt,
tables, and each other. This "normal" matter only
comprises about 5% of the universe though. Another
25% is said to be "dark matter", which we
don't really know anything about except that it
has gravitational effects, and "dark energy",
which we also don't really know anything about.
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