How does the sun works? Why does the sun shine? Why does it not burn? How long will its fuel last?

How the sun works? Why does the shine? Why does it not burn?  How long will its fuel last? 

"How the sun works" - For a scientist living in the 18th century, he would have compared it to a log in a chimney. When wood burns, it emits about one millionth of a trillion per watt of atom.

 

The mass of the Sun was well understood, and translated into about 10^57 atoms. This leads to a lifetime of about 20,000 years of sun.  But we know that the sun is at least 4.5 billion years old.  

So where does the sun's energy come from?  

From: E = MC², which tells us that energy and mass are equivalent.  If the sun can convert all its mass into 2 x 10 30 kg of energy, it will continue to burn for 15 trillion years!

But the sun does not convert all its energy into mass. It converts about 0.7 percent of its mass into energy in a process called fusion. This is when 4 hydrogen atoms fuse to form one helium atom. And using this process, the sun will last for about 10 billion years.  It is already middle-aged.

 

So how does fusion work?

You would think that since the protons that make up the nuclei of the 4 hydrogen atoms are positively charged, they repel each other.  This is true, which is caused by the force of the coulomb. It is one that spontaneously keeps the atom from fusing.

The proton must overcome an energy barrier. Once they cross this barrier, and get very close to each other, strong nuclear power captures them and joins them together.

 

 The strong atomic force is about 100 times stronger than the electromagnetic force separating the proton, but it operates at a very small range about the width of the proton.  

So how do protons close enough for this to happen?

Inside stars with temperatures of about 15 million degrees Celsius, atoms in their components are ripped: protons, neutrons, and electrons.  

Excessive pressures also force these components to pass together.  This starts the fusion, but to keep things running. The sun uses quantum tunneling. This is due to the uncertainty principle in quantum mechanics.

 

In the hydrogen to helium fusion process, the first two protons fuse.  Typically, the pair immediately separates again, but one proton at a time is transferred to one neutron.  

This is due to the weak atomic force in a process called beta decay.  A neutron is released into a proton by releasing a positron (anti-electron) and a neutrino.  The resulting proton – neutron pair is deuterium.

 

 When a positron emitted by a beta decay encounters its antiparticle (an electron), the pair forms a gamma ray, the most energetic form of the photon.  

Gamma rays eventually work their way up from the core of the Sun and into space as sunlight.  

Deuterium nuclei can merge to form helium nuclei (He-4), or they can interact with other protons to form another isotope of helium (He-3).  

The two He-3 nuclei can fuse to form an unstable beryllium nucleus (Be-6) that splits to give He-4 and two protons. Energy is released at each stage.

 

 So overall, we start with 4 hydrogen nuclei, or 4 protons, and end with a helium nucleus, or 2 protons and 2 neutrons. This is actually a fusion of our 4 basic protons. Two of them have transmitted neutrons in beta decay.

 

 Energy comes from the conversion of mass into energy.  2 neutrons and 2 neutrons are different when they are together, about 0.7% more. And this difference is responsible for almost all the energy that you come from the Sun.

 Helium has a higher binding energy than hydrogen, which is the amount of energy required to separate the nucleus.  

Hydrogen has zero binding energy because the nucleus has only one proton. There is nothing to pull apart from this.  

The difference in binding energy between helium and hydrogen is the source of energy released in the fusion. 

 

Why are the 4 nuclei of helium more stable than when they are separated together?  

Most of the mass does not come from the Higgs field. Only 1% of the mass is due to the Higgs field.  99% comes from strong force.  The energy 9 required to bind protons and neutrons together and to keep the quarks bound within the nucleus is where most of the mass of the objects is located.

  Helium atom with 4 nuclei is more stable than nuclei by themselves. This is the quantum mechanical explanation of why the sun shines.

 

OUTRO: "Mysterious Synth Drum Beat" by Nicholas Antavi, BMI

| How does the sun works? | Why does the shine? | Why does it not burn? | How long will its fuel last? |

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