Inside knowledge: Is information the only thing that exists?
来源：未知 作者：邹瘗福 时间：2019-03-01 01:16:04
Lessandroencarnacao/Stockimo/Alamy Stock Photo By Anil Ananthaswamy “IT FROM bit.” This phrase, coined by physicist John Wheeler, encapsulates what a lot of physicists have come to believe: that tangible physical reality, the “it”, is ultimately made from information, or bits. Concepts such as entropy in thermodynamics, a measure of disorder whose irresistible rise seems to characterise our universe, have long been known to be connected with information. More recently, some efforts to unify general relativity, the theory that describes space and time, with quantum mechanics, the theory that describes particles and matter, have homed in on information as a common language. But what is this information? Is it “ontological” – a real thing from which space, time and matter emerge, just as an atom emerges from fundamental particles such as electrons and quarks and gluons? Or is it “epistemic” – something that just represents our state of knowledge about reality? Here opinions are divided. Cosmologist Paul Davies argues in the book Information and the Nature of Reality that information “occupies the ontological basement”. In other words, it is not about something, it is itself something. Sean Carroll at the California Institute of Technology in Pasadena disagrees. Even if all of reality emerges from information, he says, this information is just knowledge about the universe’s basic quantum state. So we have to drill deeper. In quantum mechanics,