The Anthropic Principle as a new scientific paradigm
I never finished this thought:
The fact that we can study the Universe and formulate simple laws that govern its behavior is a miracle. For the longest time this miracle was simply attributed to God. Scientists studied physics and mathematics in order to get some insight into God's creation. The theory was that God created the Universe with brilliantly simple laws. The mere existence of laws was proof of God's existence.
Scientists no longer speak of God, so what are the alternatives? Well, even if they don't, there still is an element of faith behind physics. It's called the TOE. Physicist believe that there ultimately is a Theory Of Everything--a self contained set of laws from which all phenomena can (at least in principle) be derived. Of course, there is a pragmatic side to this belief--it proved very fruitful in unifying electricity and magnetism, and later the weak interactions. We have a quantum theory of strong interactions too. Only gravity seems to be elusive. Hence the belief in the string theory (which is so complex that nobody can prove that it doesn't contain quantum gravity).
But this trend towards reducing things to basic laws might turn out to be wrong. We know that it is wrong in mathematics--the quest to find the minimal set of axioms for mathematics was shattered by Goedel. Why should physics be different? In math, we were also able to follow the axiomatic approach ever since Euclid, and a lot of good math was (and still is being done) using it. Maybe that's the case with physics as well? We have unified whatever was unifiable (with some ad-hoc rules, as far as the Higgs mechanism goes).
There is another problem with physics that used to be easily solved within religion--why is the universe friendly to us? This is not a frivolous question. The theory of the universe that we have now is full of arbitrary constants--these constants could be anything, and yet in our universe they have very precise values that make life as we know it possible. Even the smallest variations in these values would result in a totally unfriendly universe. For instance, the actual value of the cosmological constant is just on the boundary between a universe that would immediately collapse and one that would very quickly blow up, so that not even galaxy formation would be possible. Similarly with the fine-structure constant and the masses of particles.
If it's not god who handpicked these values then who? The modern answer is more and more often... us! We picked the fine-tuned values! It's called the anthropic principle and it's very simple--only in a universe that supports intelligent life can there be observers who can appreciate it. So assume that all possible universes, with all possible values of constants, actually exist. Most of them can't support life, not to mention intelligent life. But in all the ones that happen to be life-friendly, the local scientists are amazed.
I think the anthropic principle has many more uses. For instance, I believe that in a universe that has no "laws of physics"-- meaning, a few rules that are relatively simple rather than an infinity of rules, all extremely complex--life would be impossible. Lifeforms compete with each other by creating simplified models of the environment and trying to predict the future. A predator chasing pray would never succeed if it couldn't predict the pray's position from moment to moment. The possibility of creating a model that is simpler that the actual physical system is something we take for granted in our universe. But this is equivalent to having laws of physics!
Interaction with the environment must be, at least to some extent, predictable. Without that, there's no life!
So, what I'm saying is that the existence of laws of physics in our universe follows from the anthropic principle. Those universes where you can't formulate even the simples Newton's laws of motion are just not habitable. Note: it's not necessary that the whole of physics be reducible to simple theories. Life will thrive around those parts of physics that are reducible. This makes it almost obvious that, for instance, there is no life inside neutron stars--their relativistic quantum physics is much less reducible than the simple classical physics of our environment. My theory can make testable predictions!
The fact that we can study the Universe and formulate simple laws that govern its behavior is a miracle. For the longest time this miracle was simply attributed to God. Scientists studied physics and mathematics in order to get some insight into God's creation. The theory was that God created the Universe with brilliantly simple laws. The mere existence of laws was proof of God's existence.
Scientists no longer speak of God, so what are the alternatives? Well, even if they don't, there still is an element of faith behind physics. It's called the TOE. Physicist believe that there ultimately is a Theory Of Everything--a self contained set of laws from which all phenomena can (at least in principle) be derived. Of course, there is a pragmatic side to this belief--it proved very fruitful in unifying electricity and magnetism, and later the weak interactions. We have a quantum theory of strong interactions too. Only gravity seems to be elusive. Hence the belief in the string theory (which is so complex that nobody can prove that it doesn't contain quantum gravity).
But this trend towards reducing things to basic laws might turn out to be wrong. We know that it is wrong in mathematics--the quest to find the minimal set of axioms for mathematics was shattered by Goedel. Why should physics be different? In math, we were also able to follow the axiomatic approach ever since Euclid, and a lot of good math was (and still is being done) using it. Maybe that's the case with physics as well? We have unified whatever was unifiable (with some ad-hoc rules, as far as the Higgs mechanism goes).
There is another problem with physics that used to be easily solved within religion--why is the universe friendly to us? This is not a frivolous question. The theory of the universe that we have now is full of arbitrary constants--these constants could be anything, and yet in our universe they have very precise values that make life as we know it possible. Even the smallest variations in these values would result in a totally unfriendly universe. For instance, the actual value of the cosmological constant is just on the boundary between a universe that would immediately collapse and one that would very quickly blow up, so that not even galaxy formation would be possible. Similarly with the fine-structure constant and the masses of particles.
If it's not god who handpicked these values then who? The modern answer is more and more often... us! We picked the fine-tuned values! It's called the anthropic principle and it's very simple--only in a universe that supports intelligent life can there be observers who can appreciate it. So assume that all possible universes, with all possible values of constants, actually exist. Most of them can't support life, not to mention intelligent life. But in all the ones that happen to be life-friendly, the local scientists are amazed.
I think the anthropic principle has many more uses. For instance, I believe that in a universe that has no "laws of physics"-- meaning, a few rules that are relatively simple rather than an infinity of rules, all extremely complex--life would be impossible. Lifeforms compete with each other by creating simplified models of the environment and trying to predict the future. A predator chasing pray would never succeed if it couldn't predict the pray's position from moment to moment. The possibility of creating a model that is simpler that the actual physical system is something we take for granted in our universe. But this is equivalent to having laws of physics!
Interaction with the environment must be, at least to some extent, predictable. Without that, there's no life!
So, what I'm saying is that the existence of laws of physics in our universe follows from the anthropic principle. Those universes where you can't formulate even the simples Newton's laws of motion are just not habitable. Note: it's not necessary that the whole of physics be reducible to simple theories. Life will thrive around those parts of physics that are reducible. This makes it almost obvious that, for instance, there is no life inside neutron stars--their relativistic quantum physics is much less reducible than the simple classical physics of our environment. My theory can make testable predictions!