Hey, Vsauce. Michael here.
And today, we're going to talk about water.
Because today is World Water Day.
A day about raising awareness of the fact
that, even though, here on Earth, there is
enough clean, safe, drinking water for everybody
to have enough, they don't.
In fact, a billion of them don't.
But it doesn't have to be that way.
Now first, I wanna cover how water is not
just vital and amazing, but to this day, continues
to surprise us.
For instance, the Mpemba effect.
The effect has been observed many many many
times, but has never been explained.
In fact, it is so famously anti-common sense,
whenever people throughout history have observed
it, they've tended to think that they just
did something wrong.
Which is why even though Aristotle himself
wrote about it, it wasn't until the 20th century
that it got its name.
Simply put, the Mpemba effect is the observation
that under the right circumstances a glass
of boiling hot water inside a freezer can
turn to ice more quickly than a glass of cold
water.
It doesn't make a lot of sense, but it can
happen.
A few possible causes have been thrown out.
For instance, if you heat up or boil water,
you remove some of the dissolved gas.
And having less stuff dissolved in it may
be what makes hot water easier to freeze.
It's the opposite of why we throw down salt
during wintery weather.
The salt dissolves into the water, putting
more stuff in it, making it more difficult
to freeze.
But does that account for the entire effect?
Well, some other possible explanations involve
convection currents.
A glass of warm water will contain more cycling
convection currents, meaning that the top
of that glass of water is warmer.
And a glass of warm water will tend to freeze
from the sides in, whereas the glass of cold
water will tend to freeze all across the top
down.
But once that top layer is frozen, it acts
as an insulator, so all the water below it
freezes more slowly.
The point is that we still do not have a complete
explanation of the effect.
Part of the problem is how difficult it is
to control every single variable.
Should we be using equal masses of water or
equal volumes?
Should they be in the same freezer or in separate
freezers?
And what about evaporation?
The warm water will be evaporating faster
and evaporations into thermosis, it's losing
heat more quickly than the cold water.
It's tough.
But here's what we do know.
Earth has a lot of water.
70% of Earth's surface is covered in it.
And, interestingly enough, excluding fat,
the human body is about 70% water.
But when you were born you were a big old
sack of water.
That's right.
A new baby is 78% water.
Now, that number drops to 65% by the time
that baby is 1 year old.
And it'll drop even further to about 60% when
you're an adult... man.
Adult women are only about 55% water.
This is because women's physiology on average
contains more fat, which doesn't hold as much
water as lean tissue.
In fact, fat people, regardless of gender,
contain less water than thin people.
Earth has a lot of water, but it's almost all salty.
96.5% of the water on Earth is in the oceans.
Another 3.4% of Earth's water can be found
in other large bodies of water or frozen inside
glaciers or ice caps.
But you, me, all the other animals we see,
other manufactured products?
They all contain water.
About 0.0003% of Earth's total water.
And all of the storms and clouds and rain
and thunderstorms happening contain only about
0.0001% of all the water Earth has.
That's a lot of water, but despite that fact,
almost a billion people on Earth don't have
access to potable water.
Potable comes from the Latin for "to drink,"
which means clean, safe water free from disease
and contamination.
The number of people on Earth who do not have
sustainable access to potable water is equivalent
to the number of people living inside the
United States.
Except multiplied by three.
And every year 3.5 million people die because
of non-potable water-related diseases.
That's equivalent to the entire population
of Los Angeles.
So every year, Earth, our planet, looses an
entire city of Los Angeles because people
don't have access to clean water.
So today, on World Water Day, it's worth talking
about organisations that are making a difference,
because things don't have to be the way that
they are.
Organisations like Water.org help local communities
build sustainable clean water solutions that
the community itself will own.
Now, they gave me a chance to go out to India
to see this in action, along with WheezyWaiter and Strawburry17.
Unfortunately, I wasn't able to go, but those
other two people were and they've got videos
over on their channels about their experiences.
So go check those out and if you wanna learn
more, got water.org/vsauce to see how you
can help.
And as always,
thanks for watching.
