I have a question about mining hardware and hashing algorithms. Why are there different types of mining hardware for different hashing algorithms? Why can't we use an Antminer ASIC for Ethereum or Lightcoin mining? Is Antminer more "optimized" for calculating SHA256 hashes?
The hardware you are referring to are called Application Specific Integrated Circuits (ASICs), and they are named that for a reason. It's because they are not general purpose computers like desktops, tablets, and mobile phones. Instead, they are computers designed to do a very specific thing. In the case of an AntMiner, that thing is the SHA256 algorithm. It cannot be reprogrammed to perform other hashing algorithms, such as SCRYPT (used by litecoin). In fact, it can't be reprogrammed at all.
By hard-wiring these devices to perform one, and only one task, they are much faster and more energy efficient than would be a general purpose computer programmed for the same task. This is why all Bitcoin mining is currently done with ASICs, and is not feasible to do with CPUs anymore. It's also why the same miner cannot perform anything other than what it was built for.