A Brief History of the Energy Conversion of Light [History]

Renewable and sustainable sources of light on Earth are usually associated with energy from the sun. However, scientists predict that, in about 5 billion years, this source of light, which is now about 4.6 billion years old, will no longer be sustainable and extinguish when its own energy produced by nuclear fusion in its core due to hydrogen atoms converting into helium will no longer burn hydrogen. The sun at that time will glow redhot rather than white-hot due to the cooling of its surface and become a full-blown red giant star (Figure 1) instead of a yellow dwarf star, as it is today. As it cools, it will eventually become a white dwarf star and no longer produce energy by fusion. The sun will grow significantly in size since gravitational forces will no longer be balanced in its core energy conversion process, causing it to expand.