For some intuition as to why people would think that things that can’t ever affect our future experiences are ‘real’, imagine living in the distant past and watching your relatives travel to a distant land, and assume that long-distance communication such as writing is impossible. You would probably still care about them and think they are ‘real’ , even though by your definition they no longer exist to you. Or if you want to quibble about the slight chance of seeing them again, imagine being in the future and watching them get on a spaceship which will travel beyond your observable horizon. Again, it still seems like you would still care about them and consider them ‘real’.
I like the Mathematical Universe Hypothesis for simplicity and internal consistency, but it seems like we’re assuming a lot. And it’s not as simple as all that, either. Where do we draw the line? Only computable functions? The whole Turing hierarchy? Non-standard Turing Machines? If we draw the line at “anything logically conceivable”, I would worry that things like “a demon that can jump between different branches of the multiverse” ought to be popping into our reality all the time.
If we want our theory to be predictive, we should probably cut it off at “anything computable exists”, but if predictability was our goal, why not go all the way back to “anything observable exists”?
I agree it’s hard to get the exact details of the MUH right, but pretty much any version seems better to me than ‘only observable things exist’ for the reasons I explained in my comment. And pretty much any version endorses many-worlds(of course you can believe many-worlds without believing MUH). Really this is just a debate about the meaning of the word ‘exist’.
You’ve essentially re-invented the Mathematical Universe Hypothesis, which many people around here do in fact believe.
For some intuition as to why people would think that things that can’t ever affect our future experiences are ‘real’, imagine living in the distant past and watching your relatives travel to a distant land, and assume that long-distance communication such as writing is impossible. You would probably still care about them and think they are ‘real’ , even though by your definition they no longer exist to you. Or if you want to quibble about the slight chance of seeing them again, imagine being in the future and watching them get on a spaceship which will travel beyond your observable horizon. Again, it still seems like you would still care about them and consider them ‘real’.
I like the Mathematical Universe Hypothesis for simplicity and internal consistency, but it seems like we’re assuming a lot. And it’s not as simple as all that, either. Where do we draw the line? Only computable functions? The whole Turing hierarchy? Non-standard Turing Machines? If we draw the line at “anything logically conceivable”, I would worry that things like “a demon that can jump between different branches of the multiverse” ought to be popping into our reality all the time.
If we want our theory to be predictive, we should probably cut it off at “anything computable exists”, but if predictability was our goal, why not go all the way back to “anything observable exists”?
I agree it’s hard to get the exact details of the MUH right, but pretty much any version seems better to me than ‘only observable things exist’ for the reasons I explained in my comment. And pretty much any version endorses many-worlds(of course you can believe many-worlds without believing MUH). Really this is just a debate about the meaning of the word ‘exist’.