The Anthropic Principle by Robert Nemiroff Michigan Tech Physics X: About This Course • Officially "Extraordinary Concepts in Physics" • Being taught for credit at Michigan Tech o Light on math, heavy on concepts o Anyone anywhere is welcome • No textbook required o Wikipedia, web links, and lectures only o Find all the lectures with Google at: "Starship Asterisk" then "Physics X" o http://bb.nightskylive.net/asterisk/viewforum.php?f=39 Anthropic Principle Is it a coincidence that all the physical constants like G, e, h, etc. are just that needed for life to develop?. 1. Yes, we sure are lucky. 2. No, it has to be this way. 3. Maybe a little bit. Anthropic Principle The answer is debatable, however a consensus is that: 2. No. Only those universes with life-enabling constants can observe those constants. Other universes are unobservable. This is the Anthropic Principle. First coined by B. Carter in 1973. Anthropic Principle Is it a coincidence that you are seeing this information on a computer screen? 1. Yes, I could have seen this on paper. 2. No, this is an analog of the Anthropic Principle. Anthropic Principle 2. No, this is an analog of the Anthropic Principle. The number of times a paper copy is seen will be much less than a computer screen copy. One can estimate how often each is observed. Say it is 100 to 1. Then regardless of the amount of paper and the number of computer screens in the world, only those showing this slide are relevant. Anthropic Principle The Personal Anthropic Principle Is it a coincidence that you yourself are contemplating the Anthropic Principle? With all of the billions of people, life forms, and computer forms, what chance is it that you yourself would be contemplating it? Anthropic Universe Varieties • Unique universe: Some physical Theory of Everything (ToE) can explain everything. If we understood the ToE, we would understand how it enables life. • Wheeler's Participatory Anthropic Principle: Only universes with a capacity for consciousness can exist. Anthropic Universe Varieties • Theism: God created the universe to be the way it is. • Multiverse: All possible universes exist but only those universes that develop brains can observe their own universe. Anthropic Principle RJN's view: Invoking the Anthropic Principle is a scientific attempt to include relevant information in statistical arguments. It is the physical equivalent of including "priors" in Bayseian statistics, or taking a better inventory of the number of fair trials, in frequentist statistics. Therefore,although some consider the AP "not science", I consider it an attempt at "good science". Boltzmann Brain Paradox Boltzmann Brain: A random fluctuation that develops into a universe- observing, self-aware, brain. Paradox: If entropy and disorder always increase, why do we observe such order in the universe? Restated paradox: Our existence in such an ordered universe would seem to be highly improbable in a sufficiently vast universe where many Boltzmann brains could randomly pop into existence and observe a much less ordered universe. Boltzmann Brain Paradox Which is more likely? 1. Our brains developed along side many other brains in this large universe. 2. Your single brain developed with false memories and only the impression that many other brains exist. Simulated Reality • It is not possible to distinguish a sufficiently sophisticated computer simulation from reality. • This is the philosophical Brain in a Vat paradox. • For all we know, we (or just you) may be living in such a computer simulation (e.g. The Matrix) Simulated Reality • Boltzmann's computer: Multiple computer simulations might be easier to run than brains are to make. • Penrose: The human mind is too quantum mechanical to be simulated by a conventional (non-QM) computer.