In today’s blog we chat with Dr. Luke Barnes of Western Sydney University, PhD from the University of Cambridge, on fine tuning.
David: I want to ask meaningful when, why, and how questions about the universe as a whole. Can and how does philosophy of science help?
Luke: Yes, if for no other reason than I see cosmologists make elementary philosophical mistakes when they try to speak on some of these issues. Krauss thinking that science can answer “why is there something rather than nothing?” is a prime example.
David: Provincial perspectives on the universe have often created the impression of fine tuning. We have a handle on 4% of the universe. Does that small slice of understanding not render fine tuning discussions premature?
Luke: Fine-tuning is about looking at the deepest laws of physics we have, and using the constants of nature to explore other ways the universe could have been. Sometimes a deeper understanding has led to less apparent fine-tuning, and sometimes to more. Incidentally, we have enough of a handle on the 96% to know the consequences of changing the properties of dark energy and dark matter. This is enough for fine-tuning, even if physics doesn’t know everything.
David: Do you view the low entropy of the early universe in terms of fine turning?
Luke: Yes, but it’s an initial condition so it’s not as straightforward as other cases. I certainly think that the low entropy of the universe is something that seemingly could have been very different, and the vast majority of alternatives are far less suitable for life.
David: Have we made progress on understanding the degree to which fine tuning is a real thing in your lifetime?
Luke: Yes, better theoretical calculations are continually improving our understanding of the implications of changing the constants of nature. The overall degree of fine-tuning hasn’t changed too much, though we’ve discovered that stars are somewhat more robust to changes to their nuclear physics than we previously thought.
David: Between the universe itself, the laws, and the initial conditions, what if any is more fundamental? Do you see a sense in which any of this is necessary?
Luke: I don’t see any trace of metaphysical necessity in physics. We just don’t work in those terms. Nothing in our observations demands that the universe must have been a certain way, rather than some other way. Apart from mathematical consistency, necessity doesn’t much help us. I’m not sure what “more fundamental” means. Also, it’s debatable whether we can separate the universe from its laws. This is the line between “Regularity” and “Governance” views of the laws of nature: https://plato.stanford.edu/entries/laws-of-nature/
David: Thank you Professor!