A question about fundamental constants in Multiverse idea

[ftr]

Has there been a debate as to whether fundamental constants can be chosen freely for a theory or some constraints make it unlikely that to be the case. for example the dimentionful parameters don't have a specific value, only combinations give FSC, that means(to my mind) that there is unlikely this scenario of "different" constants. Am I correct in this thinking, if not why not?

Any reference is appreciated.

 

[craigi]

Has there been a debate as to whether fundamental constants can be chosen freely for a theory or some constraints make it unlikely that to be the case. for example the dimentionful parameters don't have a specific value, only combinations give FSC, that means(to my mind) that there is unlikely this scenario of "different" constants. Am I correct in this thinking, if not why not?

Any reference is appreciated.

John Barrow has written extensively on the subject.

What it comes down to is that the best conjecture we have for why we observe the constants that we do is that we wouldn't exist in order to observe others. See the Anthropic Principle. There is some controversy about its role in science, Turok and Smolin being particularly outspoken against it. Nevertheless, Weinberg successfully predicted the value of the cosmological constant using it.

A natural conclusion is that there exists state space where the constants take different values and multivese hypotheses provide this state space. The simplest of which, under Tegmark's classification, is an infinite or sufficiently large whole universe where the fundamental constants vary in spacetime. Bounce, bubble, brane, fecund universes etc. all perform a similar role. There have been measurements that suggest that the fine structure constant may not be constant at all and most recently there has been some doubt cast on whether the cosmological constant is a constant, which would have implications for the shape of the universe. Since the fundamental constants have only ever been empirically determined we have limited reason to expect them to be universally (or mulitversally) constant anyway.

Many physicists are reluctant to discuss the subject because it involves conjecture outside of the possibility of observation and flies in the face of the tradition of Popper falsifiability. Nevertheless, current predictions demonstrate that we will lose causal contact with the outermost parts of our observable universe and a far-future civilisation in the Milky Way would see only one galaxy formed from our local cluster and arrive at an analagous incomplete view of the universe by insisting on such falsifiability.

 

[ftr]

Thanks for the reply. I new most of the things you mentioned, but I was looking for a particular angle on the subject. I will try to clarify in the next few days hopefully.