December 9, 2022
TURTLES ALL THE WAY DOWN...:
There Are No Laws of Physics. There's Only the Landscape. (Robbert Dijkgraaf, June 4, 2018, Quanta)
[N]ot everything is lost. Sometimes the path through the dark wilderness ends at another outpost. That is, at a different well-controlled model, this time made out of a completely different set of particles and forces. In such cases, there are two alternative recipes for the same underlying physics, just as with Alice and Bob's dishes. These complementary descriptions are called dual models, and the relation between them a duality. We can consider these dualities as a grand generalization of the famous particle-wave duality discovered by Heisenberg. For Alice and Bob, it takes the form of a translation between Chinese and Italian recipes.Why is this all so exciting for physics? First of all, the conclusion that many, if not all, models are part of one huge interconnected space is among the most astonishing results of modern quantum physics. It is a change of perspective worthy of the term "paradigm shift." It tells us that instead of exploring an archipelago of individual islands, we have discovered one massive continent. In some sense, by studying one model deeply enough, we can study them all. We can explore how these models are related, illuminating their common structures. It is important to stress that this phenomenon is largely independent of the question of whether string theory describes the real world or not. It is an intrinsic property of quantum physics that is here to stay, whatever the future "theory of everything" will turn out to be.A more dramatic conclusion is that all traditional descriptions of fundamental physics have to be thrown out. Particles, fields, forces, symmetries -- they are all just artifacts of a simple existence at the outposts in this vast landscape of impenetrable complexity. Thinking of physics in terms of elementary building blocks appears to be wrong, or at least of limited reach. Perhaps there is a radical new framework uniting the fundamental laws of nature that disregards all the familiar concepts. The mathematical intricacies and consistencies of string theory are a strong motivation for this dramatic point of view. But we have to be honest. Very few current ideas about what replaces particles and fields are "crazy enough to be true," to quote Niels Bohr. Like Alice and Bob, physics is ready to throw out the old recipes and embrace a modern fusion cuisine.
Why the laws of physics don't actually exist (Sankar Das Sarma, 12/09/22, New Scientist)
What we often call laws of physics are really just consistent mathematical theories that seem to match some parts of nature. This is as true for Newton's laws of motion as it is for Einstein's theories of relativity, Schrödinger's and Dirac's equations in quantum physics or even string theory. So these aren't really laws as such, but instead precise and consistent ways of describing the reality we see. This should be obvious from the fact that these laws are not static; they evolve as our empirical knowledge of the universe improves.Here's the thing. Despite many scientists viewing their role as uncovering these ultimate laws, I just don't believe they exist.A hundred years ago, an opinion like this would not have been controversial. Before then, most so-called laws of physics were all directly connected to concrete aspects of the natural world, like Hooke's law that describes how much force is needed to stretch a spring or Boyle's law about the relationship between the pressure, temperature and volume of a gas. But this started to change in the early 20th century when people like Albert Einstein took up the quest to find the ultimate theory of everything. He spent the last 30 years of his life searching for one to no avail. Dirac too believed in this view, having apparently said that all of chemistry can be derived just from his equation - though I think that particular remark is probably apocryphal.There are around 86 billion neurons in the human brain. This is less than the number of stars in the Milky Way which is just a miniscule part of the known universe. The universe seems almost infinite in comparison to the finite capacity of the human brain, leaving us perhaps little chance of figuring out ultimate laws. What is amazing is that we can make sense of some aspects of the universe through the laws of physics. It may have been Richard Feynman who first said that the issue is not how clever we humans are in figuring out how nature works, it is how clever nature is in following our laws!As we discover more about nature, we can hone our descriptions of it, but it is never-ending - like peeling an infinite onion, the more we peel, the more there is to peel.
First the ideology, then the math.
Posted by Orrin Judd at December 9, 2022 10:51 AM