Do the laws of physics stay the same wherever you are?

For this question of the week, James Tytko was tasked with finding an answer to Daniel's question on the human understanding of the universe. Luckily, cosmologist Toby Wiseman from Imperial College London was on hand to help...

Toby - Does physics change as we move around the universe? One of the fundamental tenets of cosmology is in fact that we don't live in a special location. All locations, all directions are the same, and that is absolutely what is observed when we look out into the universe. Our modern theory of cosmology uses our theory of particle physics, which we derive from collider experiments such as CERN on the Earth, and then our theory of gravitation, Einstein's general theory of relativity. Now, it isn't a complete theory, but if we are not worried about physics in the very earliest epoch of the universe, then the theory is remarkably good. We can understand everything that happens within this theory from way earlier than a second after the Big Bang. You start with this almost blank canvas of the Big Bang with little quantum fluctuations on it from what we call the theory of inflation. And those quantum fluctuations grow, cede structure because of gravity pulling structure together, and then eventually this forms the galaxies, stars and so on that we see today.

James - I think Janus' comment on our forum post for this question captures what Toby is saying about some of the unanswered questions we have and how they fit into our understanding of the universe very nicely here. They write, 'It would be possible for another civilization to have pierced the veil more deeply and have a better understanding of some of those principles than we do. This would not constitute a change in the rules, however, but just a better understanding of what they are.'

Toby - If you are sitting on a particular star somewhere, you may look down at your star and call it a different name, and you may look at the elements in it and call them different things. But this theory really predicts all of that physics. It has all of that physics in it, and we think of this theory, of the standard model of particle physics together with gravity, as something that we've discovered and uncovered rather than something we have constructed. The fact that we can write down the theory of all the forces and all of matter on a T-shirt and a couple of lines is astonishing, and it's a process of uncovering. We've got closer and closer, and the theory in many ways has got simpler and more elegant as we've honed in on it. It's very difficult to understand how that could be a human construct. This is the most accurate thing that's ever been predicted by any theory of anything, and it works. That's where my money is, anyway.