On 19 Jan 2014, at 04:05, meekerdb wrote:

On 1/18/2014 1:09 AM, LizR wrote:On 18 January 2014 19:51, meekerdb <meeke...@verizon.net> wrote: On 1/17/2014 10:18 PM, LizR wrote:On 18 January 2014 19:12, meekerdb <meeke...@verizon.net> wrote:But where does it exist? X has to be conscious of a location, aphysics, etc. If all this is the same as where I exist, then itis just a translation of this world into arithmetic. It's theflip side of "A perfect description of X is the same as X", i.e."X is the perfect description of X". If every perfect descriptionis realized somewhere in arithmetic (and I think it probably is)nothing is gained by saying we may be in arithmetic.Don't we gain less entities, making Occam a bit happier? If we canget the appearance of a universe without having to actually haveone, can't we "retire the universe" and just stick with the"appearance-of-one-with-equal-explanatory-value" ? (Not anoriginal idea, of course, I'm fairly sure Max Tegmark saidsomething along those lines regarding his mathematical universehypothesis -- that if the maths was isomorphic to the universe,why bother to assume the universe was physically there?).I'm asking why have the maths?Well (putting on my AR hat) we have it because the maths isnecessarily existent, while the universe isn't.I disagree. The maths are necessarily true, i.e. "axioms implytheorems" is true.

OK.

But why should that imply *existence*.

`It does not. Unless we believe in the axioms, which is the case for`

`elementary arithmetic. But then we believe in the existence of prime`

`numbers, and in the many relative computational states.`

We know we can invent all kinds of maths by just changing the axiomsor even changing the rules of inference.

`OK. But note that we don't do that for arithmetic, except by adding`

`axioms, or using another theory.`

Sometimes people on this list post the semi-mystic opinion thateverything=nothing, pointing to the need for discrimination. I lookat this as saying positing everything is the same as saying nothing.

`I agree. But searching a theory, we have to define the things first.`

`then in some theory the "nothing" can appear to be already Turing`

`complete, so that in that frame, the nothing theory get incarnated.`

`In classical physics you need at least three bodies to get Turing`

`universality.`

In quantum mechanics the vacuum is already Turing complete. For example.

Of course there's an answer - we can manipulate the maths - butthen doesn't that proves that the maths aren't the universe. Theywouldn't be any use as predictive and descriptive tools if theyWERE the things described. They are only useful because they areabstractions, i.e. they leave stuff out (like existence?).Well .... the maths does have that "unreasonableeffectiveness" (that you're probably bored to death hearing about).And one reason for that could be because it is - in the guise ofsome yet-to-be-discovered TOE - isomorphic to the universe.Or it could be because we, denizens of this physics/universe, inventthem.

`But that's the case we have to explained why they work or seem top`

`work, it seems to me.`

Bruno http://iridia.ulb.ac.be/~marchal/ -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.