‘…One of the strangest properties of our universe is that it has very low entropy, meaning there is relatively low disorder, or conversely a large amount of order, among all of the particles. Think of it this way: Imagine a bomb full of sand exploding onto an empty surface—that’s the Big Bang. You would expect a pretty uniform heap of sand after the explosion, but instead, our universe immediately arranged into lots of sand castles seemingly for no reason and with no help, and we don’t really know why, Stefan Countryman, a physics Ph.D. student at Columbia University, explained to Gizmodo. The Big Bang could have (and maybe should have) resulted in a high-entropy mass of uniformly distributed, disorganized stuff. Instead, we’ve got star systems, galaxies, and galactic clusters all linked together with dark voids between them. We have order.
Additionally, entropy or disorder can only increase over time—without outside help, the sand castles will erode away. In fact, according to Carroll, our observation of time is dependent on increasing entropy since the universe began. Entropy is a physical property that is completely time dependent, riding the one-way time train into the future. So: the laws of physics say entropy can only increase, and today’s entropy is still very low. Carroll says that means the early universe had to have had even lower entropy—in other words, it must have been even more organized. That has implications for what things were like before the Big Bang. “There’s a lot of people who think the early universe was simple, smooth and featureless with tiny little ripples and that’s a natural place for universe to start,” said Carroll. “Once you think about entropy… your perspective changes and you realize it’s something you have to explain.” …’