|How is it possible to breathe in zero gravity?
We breathe by expanding our lungs. This
literally pulls air into our lungs because we are
making more space inside our bodies. As long as
the air around us is thick enough we can breathe,
regardless of gravity. On Earth, gravity is what
holds our atmosphere. When astronauts go into
space they can breath, because their space ships
and space suits keep the air around them, even
though gravity is very weak.
Zero gravity has nothing to do with breathing.
If there is air, then you can breathe it; if there
isn't air, then you can't.
Gravity on planets tends to attract
atmospheres, and this means that planets with
gravity may have breathable atmospheres, unlike
the vacuum of space. However, if you have some
means of keeping an atmosphere without gravity
(for example, your atmosphere is contained inside
of your spaceship), then there is nothing
preventing you from breathing in zero gravity.
Breathing actually has to do with air pressure
rather than gravity. When we inhale air, the
diaphragm contracts and pulls down the lungs,
creating a "vacuum" inside (lower air pressure in
the lungs relative to the atmosphere outside). As
a result, air from outside your body rushes in and
we complete the inhalation.
That is a very interesting question. Let´s
clarify how gravity and air are related and what
that means for humans being able to breathe.
A person needs air (oxygen) to breathe, but as
long as they have it, then it does not matter
whether or not there is also gravity.
The complicated part is that gravity is the force
that holds us to the ground, and in fact, gravity
also is the force that holds the atmosphere, our
breathable air, against the earth where we can use
it. In space, there is no air because there isn´t
any gravity to hold in the atmosphere.
BUT, let´s say you are inside of a space ship,
which is closed container that holds air that
can´t escape. That means another force besides
gravity is keeping the air in so you can breathe
it. This force is the sealed walls of the space
So as long as there is air in the space ship, you
can breathe it, even if there is no gravity.
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