Originally from Fight Club Games If you are reading this blog there is no doubt that you've heard about Minecraft, the legendary sandbox game. In Minecraft you can make your goal whatever you want: defeat an enemy faction, build an elaborate castle, slay a dragon, create a computer that can run Minecraft within Minecraft, etc.. These goals fall under two categories: survival or creative. Survival goals typically revolve around adventure and fighting while creative goals are more geared towards art and building. Back when I played Minecraft I was always obsessed with the survival goals. I would make elaborate plans of taking over a server by working together with friends or creating alliances with other users. My plans always failed eventually but it was certainly a fun way to waste valuable time. The thing that appealed to me about the game-play of Minecraft was being the leader of a faction and building up a kingdom from scratch; I never saw a point in single-player or creative mode. Although the gameplay was impressive the code that went in to Minecraft is what really blew my mind. If you had infinite computer space you would have an infinitely large Minecraft world. By this I don't mean that you could keep building things on a blank slate, I mean that the world would continue to generate new landscapes and structures that could be navigated forever. Even more amazingly, all worlds start out with a single string of characters called a "world seed" that the rest of the world is built upon.

A generated mountain region in Minecraft. Source: http://www.minecraftwiki.net/wiki/File:1.8_Biomes_Mountain.png Most of the time world seeds are randomly generated but if you specify a certain string of characters as a seed and then use the same seed to create another world you would end up with two identical, infinite worlds. The only difference in the worlds would be what the players change and a few minor random factors (weather, monster spawning, etc.). The theory behind this could be used to create true virtual realities. I recently finished reading "Ready Player One" by Ernest Cline and was shocked by how many times I stopped and said "I thought of that first!" while going through the amazing process of reading it, something I highly recommend doing. Here is a bit of the synopsis from the official website:

"It's the year 2044, and the real world is an ugly place. Like most of humanity, Wade Watts escapes his grim surroundings by spending his waking hours jacked into the OASIS, a sprawling virtual utopia that lets you be anything you want to be, a place where you can live and play and fall in love on any of ten thousand planets."

Who does this Ernest Cline guy think he is? It was my idea to create something like that first and now he thinks he can write a whole book about it? Fortunately for me this better version of Minecraft has yet to be created. By "better version of Minecraft" I mean a version of Minecraft with tinier blocks. Much tinier blocks. Atom-sized blocks. I mean a game that has every single law of physics programmed into it. The "world seed" would be the starting conditions for the Big Bang. This would mean that the universe itself would be infinite but the matter in it would be limited to how much was at the start of the Big Bang unlike in Minecraft, where terrain will continue to generate as long as your computer can store it. That is still too much matter to comprehend, so it will have to do.

The universe is not really infinite in the way we picture it. Source: http://hubblesite.org/gallery/album/galaxy/pr2012029a/ If you would like to look into the Big Bang theory applied to computers I would recommend reading "In The Beginning was the Command Line" by Neal Stephenson. For now, though, I would like to explain why this virtual universe is impossible with our current technology. Everything computers store can be broken down into ON or OFF (0 or 1 in binary). ON is when one of the bits inside of a hard drive is magnetized and OFF is when it is not. Strings of 0s and 1s (ONs and OFFs) make up everything you do on a computer.

Bits inside of a hard drive. Source: http://techcrunch.com/2011/10/14/how-to-enable-16tb-hard-drives-just-add-salt/ The space required to hold a single bit is much more than the size of an atom. Even if computers got to the point where bits were stored in the electrons inside of actual atoms it would still require more than one bit to store the information of a single virtual-reality atom. This means that storing a virtual universe on a computer would require much more physical space than storing an actual universe in real life. Small virtual universes would still be possible but in order to create one as large as ours' we would need to rethink the entire concept of computer storage. But enough about what we can't do. Let's think more about what we could do. In Minecraft, your player begins in a random spot in the world. This starting spot is the same in all worlds created with that world seed. Players (along with animals, monsters, and other NPCs) are considered completely different from other matter in Minecraft. In real life the only thing separating us from "inanimate" objects is the way the atoms that make us up are arranged.

A player near some cows in Minecraft. Source: http://hopealexander.hubpages.com/hub/Set-Up-Minecraft-Multi-Player-With-Simple-Server In our imaginary virtual universe there is no way for players to interact with the game without breaking the laws of physics. Besides supplying the world seed for the Big Bang, how else can players change the conditions of the universe? There are three different solutions that I have for this, all of which require breaking the laws of physics:

1. Play god. A physical body is not required for this. You can just zoom around the universe faster than light and move groups of atoms around. This is the equivalent to playing Minecraft in creative mode; you can't die and you can build whatever you want.
2. Spawn a player. This approach is the most similar to Minecraft and would probably be the most convenient in multiplayer virtual universes. Spawn a body wherever you want and start playing. The user-interaction part of the body would require a "magic" brain inside of the body that connects it to what the user does with the game controller. You could be whatever human or animal you want. You could choose to spawn on a random planet or automatically search for the most Earth-like planet to spawn on.
3. Take over an animal. If you would like to disturb the virtual universe as little as possible while experiencing the thrill of a survival challenge then this would be the spawning option for you. Automatically search the entire universe for animal-like structures and then pick one to "take over." By "take over" I mean replace the animal's brain with the magic brain discussed in the previous spawning option.

All of this implies many more questions than answers. How could a virtual universe like this be stored? What defines life? Are we already a part of a computer simulation? Questions like these often lead to troubling answers. If you would like to ask or answer some of these questions feel free to do so in the comments.