Why Does the SUN SHINE? The Quantum Mechanical Reason!

Why does the sun shine? Why doesn't it burn out? How long will its fuel last? To a scientist living in the 18th century, he might have compared it to a log in a fireplace. When wood burns it releases about 1 ten-millionth of a trillionth of a watt per atom.
0:00 Sun's energy
5:00 How fusion happens
7:19 Quantum tunneling
8:25 Fusion chart
9:51 Where energy comes from
12:39 Why Helium is more stable
15:14 Future of sun
The mass of the sun was well understood, and translates to about 10^57 atoms. This leads to a lifetime of the sun of about 20,000 years. But we know the sun is at least 4.5 billion years old. So where does the sun's energy come from? from: E=MC^2, which tells us that energy and mass are equivalent. If the sun could convert all its mass 2 x 10^30 kg to energy, it would burn for 15 trillion years!

But the sun doesn’t convert all its energy to mass. It converts only about 0.7 percent of its mass to 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 approximately, 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 would repel each other. This is true, due to the coulomb force. This is what keeps atoms from spontaneously fusing.

The protons have to overcome an energy barrier. Once they get over this barrier, and get very close to each other, the strong nuclear force takes over and glues them together.

The strong nuclear force is about 100 times stronger than the electromagnetic force pushing protons apart, but it acts at only a very short range – about the width of the proton. So how do the protons get close enough for this to happen?

Inside stars extreme temperature, about 15 million degrees Celsius, rips atoms into their components: protons, neutrons and electrons. Extreme pressures also force these components to be close together. This gets fusion started, but to keep things going, the sun uses quantum tunneling. This is due to the uncertainty principle in quantum mechanics.

In the hydrogen to helium fusion process, first two protons fuse. Usually, the pair breaks apart again immediately, but once in a while one of the protons is transmuted into a neutron. This happens due to the weak nuclear force in a process called beta decay. A neutron turns into a proton by releasing a positron (anti-electron) and a neutrino. The resulting proton-neutron pair is deuterium.

When the positron emitted from the beta decay encounters its antiparticle (an electron), the pair annihilates to form a gamma ray, which is the most energetic form of photons. Gamma rays eventually work their way up from the core of the sun and out into space in the form of sunlight. The deuterium nuclei can merge to form helium nuclei (He-4), or they can interact with other protons to make another isotope of helium (He-3). Two He-3 nuclei can fuse to make an unstable beryllium nucleus (Be-6) that breaks apart to give He-4 and two protons. Energy is released at each step.

So overall, we start with 4 hydrogen nuclei, or 4 protons, and end up one Helium nucleus, or 2 protons and 2 neutrons. This is really a fusion of our 4 original protons. Two of them have just transmuted to neutrons in a beta decay.

Energy comes from mass being converted to energy. 2 neutrons and 2 neutrons separately weigh more than when they are together, about 0.7% more. And this difference is responsible for nearly all the energy that you see coming from the sun.

Helium has higher binding energy than Hydrogen, which is the amount of energy needed to pull the nucleons apart. Hydrogen has zero binding energy because there is only one proton in the nucleus. There is nothing to pull it apart from. The difference in binding energy between Helium and hydrogen is the source of the energy released in the fusion process.

Why are the 4 nucleons of helium more stable together than when they are separated apart? Most of the mass does not come from the Higgs field. Only about 1% of the mass is due to the Higgs field. 99% comes from the strong force. The energy required to keep protons and neutrons bound together and keep the quarks bound to within the nucleon is where most of the mass of objects is located.
#fusion #sun #quantumphysics
The helium atom with 4 nucleons is more stable than the nucleons on their own. That is the quantum mechanical explanation of why the sun shines.
OUTRO: "Mysterious synth drum beat" by Nicolas Antwi, BMI

[MrGold-]

When he said: „But we are quantum physicists, so let’s get one step deeper!“ This really brought a smile to my face 🙂

[johnshepherd]

I feel smarter..but if I tried to explain this to anyone else I'd sound pretty dumb. 💀😂😂😂

[rcchristian]

Can you believe some people think that the earth is flat...??? !!! They are missing a whole world of physics, chemistry and astronomy!

[SidKnight]

ME WATCHING: "Huh? Where does all the energy come from?"
ARVIN ASH: "I bet you're wondering where all that energy comes from..."
ME: 👀

[mayo]

the only problem with this channel, is that after watching I want more :)

[rahulmirlekar]

I am cancer biologist, but loves Arvin videos. If he was my teacher, I could have been quantum physicist.
Amazing videos with great explanations, can’t wait till next video.
Thanks for such amazing contribution!

[modiankit]

Arvin is doing such a good job. I wish he was my teacher.

[DrDeuteron]

Did I tell you I met Hans Bethe? It is said that after he put the Nobel prizing winning paper in the mail, he was on a date, and his date said, "Aren't the stars beautiful?"....
...he said, "Yes, and I am the only man in the world who knows how they work."
(We were not "Bros", so I was in no position to check the veracity of this legend).

[Ikbeneengeit]

This could easily have been a 10 hour long video without running out of fascinating science, thank you.

[nHans]

Arvin, you pointed out a very important fact—in the Sun's nuclear reaction, only 0.7% of the mass gets converted to energy.

In fact, one of your viewers asked why not a 100%. I explained the law of conservation of baryon number as well as I could. But I'm sure a video from you would be worth a 1000 times as much. Yup, that's a request—a video on the lesser-known conservation laws such as charge, parity, baryon number, lepton number etc.


I have another reason for requesting this. Some enthusiastic but misguided proponents of nuclear fusion forget this 0.7% limit. They tell you how much energy _E_ we humans consume, how much fossil fuel we burn for that energy, and how much pollution we cause because of it. Then they use Einstein's famous _E = mc²_ and arrive at a ridiculously small amount _m = E/c²_ of uranium, plutonium, or some other nuclear fuel that could replace all those gigatons of fossil fuels. A lot of naïve people get convinced by such false arguments. But, as you mentioned in this video, they are off by a factor of more than 140. But you did not explain why. In order to have a rational and fact-based discussion on such topics, it would be nice to have the science explained in a simple and clear fashion, as you do in your other videos.

[informing_]

Best school ever, thanks for inspiring me to start learning quantum physics and science in general, thanks to this channel and the internet my life took turn and from a mainstream person I began to search more and more, many things including installing solar panels to get my electricity, making circuits, making ethanol from sugar and even fruits began here, thanks for the great content quantum physics is very interesting and fundamental I hope we learn more about it, but as we learn more I only have more questions haha

[jampoles]

Arvin Ash exudes the energy of happiness + enthusiasm C square

[DavidFMayerPhD]

"When wood burns it releases about 1 ten-millionth of a trillionth of a watt per atom."
should be
"When wood burns it releases about 1 ten-millionth of a trillionth of a JOULE per atom."

[themagic]

Arvin does such a great job of explaining things that he might be the world's single greatest source in terms of making the world more intelligent.

[onebylandtwoifbysearunifby]

It's pleasing to see quantum explanations.
Quantum physics has been hidden away for decades.

Explanations without quantum components have always seemed incomplete, and harder to understand.

Hooray for the Standard Model,
incomplete as she may be.

[michaelwolske]

Love the way you teach this material. The flow is engaging and the graphics make the content more easy to understand

[wellbeef]

I would like to say, thank you Arvin. I am a very recent subscriber to your content but have learned so much from you already. The first video I watched of yours was the "How nuclear fission works" and because of how you deliver the facts and theories, made re watching and absorbing the info very easy. Keep up the great work and I hope you and your channel get the recognition it deserves.

[meows_and_woof]

Can you please make a video on what if we could see in a every wave length? I mean including the X-ray and uv waves. All the possible waves of electromagnetic fields

[SamsChannelsan]

I loved his statement at 10:45

"We are Quantum-Physicists Darn it!"

[juandiez]

This is by far the best channel I've subscribed in. I'll definitely support it and try to make as many questions I possibly can!!! Thanks so much for enlighten my curiosity and show and explain so many facts, wich, most of the times, I was wrong about them. Thanks so much, thanks a lot for teaching so complicated science in such an easy way. Thanks