Wonders of the Universe, a new BBC series by Professor Brian Cox, explores the Universe and everything about it. The first episode, entitled Destiny, talks about time, death, and the end of the Universe. Kind of odd for a beginning, but fascinating none the less. I would highly recommend watching it, even if you’re not a fan of physics, as Professor Brian Cox does an amazing job of explaining things clearly and concisely, whilst simultaneously making staring into the distance cool. I know I for one learnt a lot from the episode!
Perhaps the most important concept he explored was the Arrow of Time. The basic premise of this is that as each moment passes, things change, and they can’t be undone. This results in a future that will always be different from the past, thereby driving the evolution of the Universe. One of the major factors causing this is due to the second law of thermodynamics: entropy. Entropy is a natural state whereby, if left untouched, things go from an ordered state to a disordered state, which can also be written as going from a low entropy to a high entropy. Entropy always increases over time, and is the reason why time only runs forwards.
Another fascinating concept is that when you look up at the stars, you are looking back in time. Light takes time to reach Earth, so whatever light you see from the stars has already happened a long time ago. An amazing example of this is GRB 090423, a small red dot (seen in the centre of the image on the right) first observed on April 23rd 2009. This was discovered to be the oldest known object in the Universe, as the light emitted by it took approximately 13 billion years to reach us. 13 BILLION years. That’s a huge number! Considering the Universe is approximately only 13.7 billion years old, this massive star lived, exploded, and burnt out to form a black hole roughly 630 million years after the Big Bang. That is just mind bendingly insane. It shows that even at the start of the Universe, stars were dying. Our sun will probably explode in 6 billion years or so, leaving a white dwarf, which will cool and transform into a black dwarf, which will become a black hole, before the Universe as we know it ends. But don’t worry, this won’t happen for approximately another 10 thousand trillion trillion trillion trillion trillion trillion trillion trillion years. So don’t hold your breath.
Enjoy life, however brief on the cosmic scale it is. Onwards!