Why and how is sun producing energy?
– The ‘how’ is straightforward: Nuclear fusion of hydrogen atoms to produce Helium. Since there is less energy required to hold Helium proton/neutron together as compared to the energy required to hold them in hydrogen atoms, the energy difference is released as photon energy that reaches earth at some point. So as long as there are sufficient hydrogen atoms in the sun to keep this fusion process going, we should expect to continue to have solar energy as a source.
– The ‘why’ is the hard part for me right now. Fusion takes place only at extremely high temperatures (like at millions of kelvin); and that temperature is reached at sun’s core due to its very strong gravitational force. Whenever gravity comes into picture, I always pause myself as I frankly do not understand gravity much. I know what gravity is but why there is gravity is something I do not understand. We attribute so much of our understanding to gravitational forces, but not really sure how it plays. Are there magnetic forces acting as gravity or is there a field in another dimension that is acting as gravity etc.?
Anyways, without digressing further, the next question is ‘how did those hydrogen atoms come together into the sun’ or basically ‘how did that hydrogen fuel with that huge amounts of energy get stored in the sun’?
The answer is probably ‘big bang’, when all energy exploded out into the universe and a tiny fractions of it got together to form matter as we understand it.
The next obvious question is ‘was all the energy currently in universe present at that point of big bang?’ And how did that big bang contain so much energy?