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Atoms are ridiculous and unbelievably
small.

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A single human hair is about as thick as

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500,000 carbon atoms stacked
over each other.

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Look at your fist, it contains trillions
and trillions of atoms.

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If one atom in it were about as big as a
marble, how big would your fist be?

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Well… about the size of Earth.
Hm… still hard to imagine?

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Let’s try something different

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Look at your little finger.

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Imagine that its tip is as big as the
room you’re sitting in right now.

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Now fill the room with grains of rice.

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One rice corn represents one cell of your fingertip.

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Now let’s zoom in on the rice corn.

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And now, one cell is as big as the
room you’re in right now.

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Let’s fill it with rice again.
This is about the size of a protein.

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And now, let us fill all the empty spaces
between the rice corns

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with fine grains of sand.

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This is roughly how small atoms are.

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What is an atom made of?

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Let us just pretend that atoms look
like this for a minute

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to make it easier to understand.

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An atom consists of three
elementary particles:

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neutrons, protons and electrons.

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Protons and neutrons bind together and
form the atom core,

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held together by the strong interaction,

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one of the four fundamental forces in
the universe.

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They are made from quarks and
held together by gluons.

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Nobody knows exactly how small quarks are.

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We think they might literally be points,
like in geometry.

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Try to imagine them as being
zero-dimensional.

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We suspect that quarks and electrons are

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the most fundamental components
of matter in the universe.

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Electrons orbit the atom core. They
travel at a speed of about 2,200 km/s,

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fast enough to get around the Earth in
just over 18 seconds.

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Like quarks, we think electrons are
fundamental particles.

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99.999999999999%

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of an atom’s volume is just empty space…
Except that it isn’t.

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What we perceive as emptiness is actually
a space filled by quantum fluctuations,

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fields that have potential energy and
build and dissolve spontaneously.

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These fluctuations have a fundamental
impact on how charged particles interact.

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But that’s a topic for another video.

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How much space do the core and
electrons actually fill?

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If you were to subtract all the spaces
between the atom cores

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from the Empire State Building,
it would be about as big as a rice corn.

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All the atoms of humanity would
fit in a teaspoon.

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There are extreme objects where states
like this actually exist.

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In a neutron star, atom cores are
compacted so densely

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that the mass of three Suns fits into an
object only a few kilometers wide.

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By the way, what do atoms look like?

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Well, kind of like this.

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Electrons are like a wave function and a
particle at the same time.

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We can calculate where an electron might
be at any given moment in time.

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These clouds of probability,
called orbitals,

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are where electrons might be
with a certainty of 95%.

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The probability of finding an electron
approaches 0

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the further we get away from
the atom core,

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but it actually never is zero, which
means that, in theory,

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the electron of an atom could be on
the other side of the universe.

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Okay, wait a second.

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These strange thingies make up all
the matter in the universe.

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For many dozens of known elements,

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you don’t need many dozens of
elementary particles, just three.

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Take one proton and one electron,
and you have hydrogen.

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Add a proton and a neutron,
you have helium.

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Add a few more, you get carbon,
a few more, fluorine,

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even more, gold, and so on.

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And every atom of an element is the same:

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all hydrogen atoms in the universe,
for example, are the same;

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the hydrogen in your body is exactly
the same as the hydrogen in the Sun.

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Do you feel confused right now?
We certainly do!

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Nothing on this scale of the universe
makes any sense in our world,

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and we’ve not even begun talking about
quantum mechanics or the particle zoo,

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which are even stranger!

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Our model of atoms has changed a number
of times since we first conceived it,

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and the current one will certainly
not be the last.

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So let us support scientists and research

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and wait for the next wave of
mindboggling new information

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about this strange world that is the
basis for our existence.