Though science had made inroads into the mysteries of the Universe by 1900, many unknowns remained (and many still remain) unsolved including how the sun created and sustained continuous heat and light. The Egyptians thought the sun was a chariot of fire pulled across the sky by a god who presumably rekindled the fire each morning. In more modern times some suggested the heat source must be some sort of ‘burning’ like a furnace. Others thought that the sun was a huge rock glowing yellow hot, though that did not answer the question of what caused the heat in the first place. Another theory was that the sun was a huge lump of burning coal. Since coal was discovered to be a product of Earth biology from millions of years ago, that idea was discarded. Most scientists understood that any sort of conventional ‘burning’ would have consumed the fuel and ‘gone out’ long before. Yet, even so, the accepted theory was that the sun produced energy by an as yet unexplained type of chemical combustion. But then this guy, Einstein, came along with the deceptively simple formula, E=mc(squared), and opened the door on the discovery of an entirely new type of energy: the energy that exists within an atom.
The original bits of matter in the Universe were the simplest atoms, mostly hydrogen and some helium, yet in quantity so staggering as to defy even imagination. The other forms of matter like oxygen, iron, gold, carbon, uranium and so on did not exist. Through a process of gravitational collapse and attraction, the hydrogen and helium began to be attracted to areas of denser concentrations. Eventually these areas became billions of galaxies each made up of billions of stars. It is within these first generation stars that the more massive elements began to be ‘forged’. Our sun did not exist at that time. It is a third generation star made up of mostly hydrogen but also contains, along with the planets, a substantial dose of all the other elements, including everything that we are made of. Without the existence and demise of the previous stars, there would not be a sun or the Earth.
Why is that? What process within the sun and stars can create the other elements beginning with just primarily hydrogen? First of all the sun is huge. A million Earths could fit inside it. All that mass creates gravitational pressure that ‘squeezes’ the sun. The ‘squeezing’ creates tremendous pressure (and heat) on the hydrogen atoms at its core. This process forces hydrogen atoms to merge (fuse) together to form helium atoms. When this occurs, additional energy is released. Scientists from many countries have copied the basics of this process and produced the world’s nuclear arsenal; i.e. bombs. The interior of the sun is a nuclear furnace. Each second it creates the energy of a trillion bombs converting over 500 million tons of hydrogen into helium. It is the energy from this ‘furnace’ that eventually radiates into space in all directions and reaches us as heat and light.
So you may wonder why doesn’t the sun fly apart? The answer is gravity. The force of gravity pulling the sun ‘inward’ matches the power of the nuclear activity forcing the sun ‘outward’. The two forces have reached a ‘stalemate’ or balance where, thank goodness, neither wins. You may also wonder what happens when the sun runs out of hydrogen? While stable, the sun will never actually run out but when the level of hydrogen drops below a certain level and nuclear activity slows, gravity will slowly squeeze the sun ‘tighter’, the temperature of the core will increase and become hot enough to fuse helium atoms into the heavier elements up to and including iron, thus giving the sun a lease on life. It is when the sun reaches the end of producing iron, however, that the gravity of the sun will not be strong enough to squeeze it any further and element production ceases. The elements more massive than iron are produced in the explosive end of stars many times larger than the sun.
The processes described here are somewhat more complicated but then this is not a physics lesson. What Einstein’s insight discovered is that there is a staggering amount of energy stored up in what we think of as ordinary matter, and vastly more than what a simple fire or other chemical reaction can produce. It answers the question of how the sun can produce such incredible amounts of energy, and also how it can continue to produce energy for billions of years into the future.
Email Terry Mejdrich at firstname.lastname@example.org.