In E equal m c squared. E is energy. m is mass. c is the speed of light. So what it's basically saying is that mass and energy is
the same thing. So by getting lighter the sun can release the mass
as energy, and that's how the Sun is shining. At the same time, byproduct
called neutrinos. So,
if you would like to answer the question, how
do we know that this reaction is indeed happening inside the Sun, there's an answer to this question?
Namely, we can detect these neutrinos,
and this neutrinos such goes like objects, they can just
penetrate the entire Sun with great ease.
It can penetrate the entire Earth with no problems at all, and as a result they
must be a hundred trillion
neutrinos going
through your body every second. So, the Sun
is converting mass
to energy. That’s what it's doing, and that's
how the Sun shines.
And this is far more powerful source of energy than
any chemical reactions. So the Lord Kelvin was wrong.
The sun is going to
last a lot longer. But then the question is, can
we really test this?
By detecting these weird particles called
neutrinos. How
do we ever detect these neutrinos to find the proof that this is indeed happening at the center of the Sun. To see the evidence that this
reaction is happening at the center of the sun naming that the sun is shedding its mass in
converting it to energy.
We would like to verify that these neutrinos are indeed coming
from the sun. So
that would be a challenge if you would try to detect these neutrinos coming from the
sun.
But there is a way to see these nearly invisible neutrinos. Basically that, neutrinos
has such a low probability
to interact with anything; we need to
build a big target. If the target is big enough, there may be some small chance that neutrinos
might cause some reaction inside this big target.
So, we need to have something really big. We
believe the sun is burning atoms by fusing four hydrogen’s
atoms into helium
with the neutrinos of the by product. Those neutrinos
are going through our body every second like trillions
of them. They don't interact very much so
we don't feel them, but once we have a big tank there
is some chance that neutrinos
might cause some reaction and even with this huge tank and so many neutrinos
coming from the sun, it turns out that we may
be able to see maybe five neutrinos a day, and so
that’s very hard to see. But if you just wait long enough like five years keep recording these neutrinos
coming from the sun time and time eventually we
can take a picture of the sun after a long exposure. This is
remarkable.
This is the way we now have a
firm evidence that the inside the sun indeed you are forcing these elements to come together.
Fuse them together to build a bigger element. That’s what
happening inside the sun. So, Lord Kelvin was wrong.
He was assuming that the sun burns based on like chemical fuel, but that was not the case.
The nuclear fusion is far
more powerful than burning chemicals.
So now we have a revised estimate how much the
sun is going to last. The answer turned out to be about four and a half billion years. That's a big difference, right? So we don't have to worry about the sun sort of a, going out of
steam in 1000 years from now. It’s going to happen four and a half billion years from now.
But it would have
come to an end and what would happen then is that there is no hydrogen fuel anymore the
sun can use to power up, and once there’s no power
of the sun then it can't
support its
own weight.
It would crush at the center of the sun. As a result the outskirt
of the sun would
blow up. It becomes much, much bigger,
to the extent that it
might end up swallowing the earth.
That's how big the sun is going to become. It’s
called a red giant.
So obviously, before this happens, we need to come up with an escape plan. We need to build a big spaceship or something.
We go to some other
planet in four and a half billion years. That’s certainly a subject of a research.
contd....
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