But that is not an accurate quote of what Tegmark actually says.
Verbatim Tegmark's words are; "our physical world does not just have some mathematical properties, it has only mathematical properties."
I will keep this in mind as I read. I would like to understand exactly what it is that Tegmark is actually asserting.
Mario Livio recalls how Einstein wondered why mathematics worked so well in explaining the universe as we see it.
I've often wondered why hammers work so well in building houses. But houses are not hammers. Again you'd say I'm mischaracterizing Tegmark. You're probably right.
Thus the first question is; does the universe have indeed any (some) mathematical properties and what constitutes mathematical properties?
Well first, are the properties inherent in the universe? Or is our math the way our mind understands the world, no different in principle than the way a bat uses sound to experience the world?
Obviously it does not recognize our mathematical symbolisms, but we are able to recognize universal mathematical patterns and are able to unlock its mysteries by means of our symbolic mathematics. So it would seem that the assumption of some mathematical properties is not unreasonable.
On the contrary, it's an entirely unreasonable metaphysical speculation. When you have a hammer everything looks like a nail. When you have a brain wired for binary logic it perceives the world in terms of binary logic. Bumblebees have an understanding of the world too. It just doesn't happen to involve the historically contingent subject of human physics. The claim that the mathematics is "literally" true about the world is a gross conceit. Tegmark acknowledges this point (in the paper) and admits that when he says the world obeys the laws of physics, he doesn't mean to imply that we know all those laws yet!
The assumption that our models PERFECTLY represent some aspect of reality has no support. Every physical theory is an approximate. How do you know there is ANY "ultimate" law?
If so, is it reasonable and logical to propose that the universe might indeed have only (pervasive) mathematical properties, which eventually can lead us to unlocking the remaining mysteries?
The premise is absurd on its face and as false as false can be. Math is the toolkit we use to deal with the world. It's not the world itself nor necessarily any part of it. But if for sake of discussion I grant you your false premise, then I suppose your conclusion holds vacuously. That's the best I can do in granting a tiny degree of agreement. Since your premise MIGHT be true but you have no proof, and I have plenty of evidence it's false.
If it is not reasonable and logical to propose that the universe functions in a mathematical fashion, then what is the alternative?
Ah that's the fallacy that says, "If you're so smart, what would YOU do?" I haven't got the answer here. I just note that the claim that there even ARE any ultimate laws of the universe is a metaphysical speculation. All known physical laws are historically contingent approximations that are breakthroughs one century then refined and seen in a larger context the next. It's a game of successive approximation. Any speculation past that is not science. Science is descriptive and not explanatory, that's the great lesson of Newton's "I frame no hypotheses."
Can anyone imagine a different set of universal laws more informative than our human perception of reality and ability to translate that perception with our symbolic mathematical language?
The caterpillar on a leaf on a tree in a forest has a theory of his own world too. What makes anyone think we're nature's final product? If intelligence evolves past us (either elsewhere in the universe or ourselves in the future) perhaps our own contemporary physics will seem as quaint and wrong as the phlogiston theory of heat and the geocentric universe.
I can't, but I am wide open to suggestions.
I'm only questioning Tegmark's metaphysical assumptions. I can still grant him his IF this THEN that, which is all he's really claiming in fact. He doesn't assert his premises, he only examines their logical consequences. I can live with that.
I'm going to go read some more.