As you’re going by your day to day business, somewhere far, far away, around 150 million kilometers to be exact, big things are going on. In just a second, enormous amount of energy, too big for us to even comprehend, is being released by hydrogen isotopes combining to form helium atoms. This is called nuclear fusion, and is the power source of stars, including our Sun, 150 million kilometers away. But what are the physics behind it, and can we one day use it to power our world?
Nuclear fusion had first been suggested in 1920 to explain where stellar power came from, and later on, in 1932, laboratory fusion was achieved for the very first time. Not long after, humanity, as it usually does, began attempting to militarize fusion and the first thermonuclear fusion bomb was developed in 1952, earning the name hydrogen bomb. However, even though fusion was achieved in the H-Bomb operation, for it to be used as an energy source, controlled and self sustaining fusion was required. However, the technology for fusion reactors was not and still is not fully developed, and may not even be possible. So, if we're not even sure if we'll be able to reach fusion, why do we waste so much money on developing new technologies? Would it even be worth it?
To answer that question, we first need to understand how and why fusion works. To put simply, the fusion in our sun works by fusing two hydrogen isotopes (hydrogen atom with differeng numbers of neutrons) into a helium atom. Now, this might sound counter-intuitive, as you would need energy to combine things, right? Well, that’s true, which is why fusion is so hard to achieve and needs extreme environments like the cores of starts to occur. However, while fusion requires a great amount of energy, the output is that much more. The reason being that the newly-fused helium atom has a mass lower than that of the two deuterium atoms. So, where does the remaining mass go? The answer is, it’s converted into energy. The equation for the conversion of mass into energy is the infamous "E=mc²", where E is energy, m is mass and c is the speed of light. As you can tell, the energy output here would be massive, seeing as the speed of light by itself is a pretty large number (almost 300 million meters per second!) and multiplying mass by that number squared gives us a pretty big result which is why fusion produces so much energy. And not just that, but fusion produces no unwanted products and does not release any harmful gasses. On top of that, the fuel required for fusion, deuterium and tritium, is either abundant or possible to synthesize. So, if we were to achieve sustaining fusion, we would have ourselves a very, very, very long term and extremely clean kind of energy.
Even though the results are promising, fusion energy still remains a dream to humanity. For now, the output does not match the cost. However, each year, new discoveries are being made and science is leaping forwards, and it seems optimistic, however rightfully so, to imagine a future powered by fusion.