# The Hidden Reality

As if I wasn’t lucky enough to meet Brian Greene, (I have proof don’t worry everyone….*see image below*) I also bought one of his many famous books. The one I chose was *The Hidden Reality*. I was even luckier and also had him sign the book for me. I probably sound like I am “fan-girling” over this man but-let’s be honest I really am. I want to talk a little more about the book and Greene. He is a theoretical physicist who has done lots of work regarding the string theory. What is the string theory you might ask? I’ll give you a little history lesson. Firstly, when the electron was discovered, it unleashed the study of particle physics. Particle physics was developed using quantum mechanics. Einstein focused a great amount of time on the subatomic particles and created the Special Theory of Relativity. He then took Newton’s law of gravitation and created the General Theory of Relativity. Einstein’s findings led to a few predictions that are very intriguing: black holes and an expanding universe. The problem with particle theory is that it only works when we neglect gravity. The string theory was founded to determine the relationship between mass of a particle and the spin. Physicists discovered there to be a particle with no mass and two units of spin-also known as the graviton. If they implemented the quantum field theory to gravitons, the math did not work. Particle interactions occur at a single point of spacetime, at zero distance between the two particles. In string theory, the strings collide over a small but finite distance and the answers do make sense. So here’s a little example to make everything seem understandable: “Think of a guitar string that has been tuned by stretching the string under tension across the guitar. Depending on how the string is plucked and how much tension is in the string, different musical notes will be created by the string. These musical notes could be said to be **excitation modes** of that guitar string under tension. In a similar manner, in string theory, the elementary particles we observe in particle accelerators could be thought of as the "musical notes" or excitation modes of elementary strings. In string theory, as in guitar playing, the string must be stretched under tension in order to become excited. However, the strings in string theory are floating in spacetime, they aren't tied down to a guitar. Nonetheless, they have tension. The string tension in string theory is denoted by the quantity 1/(2 p a'), where a' is pronounced "alpha prime" and is equal to the square of the string length scale.”

So with that, Greene has been studying the possibility of parallel universes. To quote Greene, “There are only so many ways matter can arrange itself within that infinite universe. Eventually, matter has to repeat itself and arrange itself in similar ways. So if the universe is infinitely large, it is also home to infinite parallel universes. Does that sound confusing? Try this: Think of the universe like a deck of cards. "Now, if you shuffle that deck, there's just so many orderings that can happen," Greene says. "If you shuffle that deck enough times, the orders will have to repeat. Similarly, with an infinite universe and only a finite number of complexions of matter, the way in which matter arranges itself has to repeat."

I think studying more about this and having a deeper understanding is a goal I have. I am so excited to read this book and learn more about all the possibilities out there.

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