The sun is a wondrous thing. The light and heat it provides is vital to us as a human race to survive. As most people know, it takes a little over 8 minutes for light to cover the 150 million kilometres from the sun to the Earth (as the speed of light is approximately 300,000 km/sec). Well, 8 minutes and 170,000 years. Photons of light that travel from the core to the surface of the sun (some 700,000 km away) would take less than 3 seconds if the path was clear. However, as the core of the sun is so dense, there are many collisions happening all the time, dramatically slowing the movement of the photons. Supremely ancient light we’re seeing then! (New Scientist).
The speed of light is the reason why, when you look up at the stars at night, you are seeing into the past. I thought you could also apply this to everything you see around you, in that it takes a fraction of a second for light to reach your eye (3.3 nanoseconds for light to travel 1m), so everything you’re seeing could be considered to be in the past. But I didn’t take into account the time it takes for light to travel from my eye to my brain. It takes a tenth of a second for light, once it has hit my eye, to be perceived by my brain. The brain compensates for this by generating a perception of what the world will look like in a tenth of a second. In this way, you aren’t seeing reality, but a construct of it. You are actually seeing the future the whole time! How incredible is that? It also partly explains why optical illusions work so well on us.
From ancient sunlight to time bending brains, the speed of light and how we perceive it is phenomenal. Here’s to seeing the past and the future! Onwards!