If I had evidence it wouldn't be a belief. I did say "I believe".
The only thing that would be close to evidence would be that the big bang theory states that the physical laws didn't all apply at the beginning of big bang (if I understand it right). Space-time came to be, but for instance certain laws in nature relating to particles, or chemistry, and such, didn't exist yet. This might be an interesting topic for another thread.
I've read some article once about it, and I think I've seen some other people writing about it too.
Hang on. I'm doing a google to see if there was something that originally got me thinking in this direction...
Like this one:
Quasars Reveal That Laws of Nature Change Over Time
Or this one:
Changes spotted in fundamental constant - physicsworld.com
And I found a few articles on some universities with people arguing against immutable laws. After all, the universe has a temporal aspect, which already suggests mutability.
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And one more thing, everything else evolves, why not the things that we consider and think of as laws?
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Also, the concept of a bubble multiverse, each universe has its own set of laws, which suggests that laws can be different, and not a fixed thing. Why not each universe also have changing laws?