You're reading the public-facing archive of the Category Theory Zulip server.
To join the server you need an invite. Anybody can get an invite by contacting Matteo Capucci at name dot surname at gmail dot com.
For all things related to this archive refer to the same person.
Keith Elliott Peterson (Sep 07 2024 at 00:08):Is the idea that there are one or more extra-cosmic beings that created the universe (or multiverse if that's what you're into) a good or bad philosophical hypothesis?
Does the existence of all things require a creator, or is there a sufficient bootstrapping explanation for why things exist? Could there ever be? Do things eventually just "pop" into existence like initial morphisms in set theory, or is it just symmetry breaking all the way down?
Madeleine Birchfield (Sep 07 2024 at 00:27):The idea that one or more gods are needed to create the universe presumes that there is some finite time in the past when the universe was created.
Note that we don't have any observational scientific evidence of anything before the cosmic microwave background. It is possible that our current model of cosmology, Lambda CDM, breaks down sometime before the cosmic microwave background was formed. This would allow the possibility of the universe continuing on forever into the past, with no beginning, thus making this whole question moot.
Madeleine Birchfield (Sep 07 2024 at 00:33):But what happens at time ? Well, that is a time that we don't even know exists, and if we assume that time is correctly modeled by the real numbers, then that time doesn't exist.
John Baez (Sep 07 2024 at 13:18):Is the idea that there are one or more extra-cosmic beings that created the universe (or multiverse if that's what you're into) a good or bad philosophical hypothesis?
I don't know what counts as a good or bad 'philosophical hypothesis' so I have rather little to say about this, except to note that sometimes the assumption of an extra-cosmic creator is used to put an end to questions about how the world works - a manuever that I find counterproductive in the realm of science.
John Baez (Sep 07 2024 at 13:23):The question of 'what happened before the Big Bang?' or 'does the concept of before the Big Bang even make sense?' is much more interesting to me. Physicists have a bunch of fascinating theories about this. For example, Ashtekar argues that loop quantum gravity predicts that the concept of linearly ordered time breaks down near the Big Bang, but that you can approximately think of our universe as having a time-reversed Big Crunch before the Big Bang. He calls this theory the Big Bounce:
This short review is addressed to cosmologists. General relativity predicts that space-time comes to an end and physics comes to a halt at the big-bang. Recent developments in loop quantum cosmology have shown that these predictions cannot be trusted. Quantum geometry effects can resolve singularities, thereby opening new vistas. Examples are: The big bang is replaced by a quantum bounce; the 'horizon problem' disappears; immediately after the big bounce, there is a super-inflationary phase with its own phenomenological ramifications; and, in presence of a standard inflaton potential, initial conditions are naturally set for a long, slow roll inflation independently of what happens in the pre-big bang branch.
John Baez (Sep 07 2024 at 13:29):But this is just one of dozens of theories. For these theories to be good science, they need to make testable predictions. (Ashtekhar is trying to provide such predictions.) One way to test such predictions would be to study the gravitational background radiation left over from very earlier times, much earlier than the microwave background radiation, since gravitational waves must have decoupled from matter long before 380,000 years after the Big Bang. The LISA satellites will try to measure the gravitational background radiation sometime in the 2030s.
This will be vastly more exciting to me than anything anyone says about extra-cosmic creators. There's just more solid stuff for me to sink my teeth into: I can think about the experimental challenges of launching 3 satellites into space to detect low-frequency gravitational waves, the theory of how gravitational waves interact with the extremely dense matter at very early times, the various theories of quantum gravity and how people have used them to guess what happened 'before the Big Bang' or how the ordinary concept of time breaks down under extreme conditions, etc. etc. etc.
John Baez (Sep 07 2024 at 13:39):So, to me the main problem with "the idea that there are one or more extra-cosmic beings that created the universe" is that it's boring compared to many other subjects. It may produce a brief 'sugar high', but whenever I spend more than a few minutes contemplating it, I wonder what solid knowledge I'm going to get in the end, and I always decide that it's much better to spend time in some other way.
In fact these days I even avoid thinking about quantum gravity, for essentially the same reasons, though it's a lot more substantial than theology: at least there's a lot of good math and experimental physics connected to quantum gravity.
Julius Hamilton (Sep 07 2024 at 13:44):One response, that only occurs to me because of things I have learned over the past year, is:
The question puts forward a particular conceptual model - “Gods”, “universe”, “causation”, “existence”, and presumably assumes the relevance of related categories like “time”, “space”, etc.
It then asks for the resolution of a certain question “over that conceptual model”. If the conceptual model is sufficiently precisely defined, that question may be very answerable. You can think of it as a provable conjecture in a logical system, or maybe as a query over a data model.
Maybe things like Gödel’s ontological proof fall prey to this same mistake, which is that for a given conceptual model someone is using (either explicitly defined or implicitly assumed), it might be easy to make complete, even formal logical argument for what kinds of conclusions can be drawn from the premises of that model.
The fallacy is that we may have no justification for why that conceptual model is relevant to “the thing around us” (existence, the universe, etc.) So long as we make use of even basic assumptions like the existence of “time”, “the universe”, etc., and certain minimal properties they have, we are distracting (rhetorically speaking) ourselves by resolving logical propositions about a conceptual model we built in our minds, when we have no way of knowing if the assumptions built into those categories we are using, like “time”, are accurate descriptors of “the thing we actually want to describe” (the world around us, etc.)
This is what I think about when I hear things like “quantum gravity may imply that time did not exist before the Big Bang”: if we try to work out a logically perfect answer to questions like “does there have to be a “first mover”? How could something come from nothing?””, even if our logic within a chosen ontology is impeccable, we may be blinded by how the ontology we are using has nothing to do with “the thing around us” (the world).
Julius Hamilton (Sep 07 2024 at 13:47):And in case it wasn’t clear, I wasn’t discounting those ideas about quantum gravity, but using it as an example of discovering that one’s basic assumptions about the world, like time as an infinite continuum, can turn out to be very inaccurate.
John Baez (Sep 07 2024 at 13:49):I agree, Julius: one great advantage of focusing on "the thing around us" by doing careful experiments is that doing so may reveal that our preconceptions about the nature of reality are approximations that break down under conditions that we hadn't experienced yet. Examples: quantum mechanics and general relativity.
Madeleine Birchfield (Sep 07 2024 at 14:17):Also, there is the theory held by some polytheists that the universe created gods, rather than gods creating the universe.
Morgan Rogers (he/him) (Sep 07 2024 at 20:21):One could rephrase Keith's question (up to delineating limited boundaries for "the universe") as "Why is there something rather than nothing?" Extra-cosmic beings seem to just push the problem down the road a little, don't they?
Julius Hamilton (Sep 08 2024 at 17:10):Morgan Rogers (he/him) said:
One could rephrase Keith's question (up to delineating limited boundaries for "the universe") as "Why is there something rather than nothing?" Extra-cosmic beings seem to just push the problem down the road a little, don't they?
I’m just engaging with you in conversation rather than seeking to rebut you; I think some would argue that metaphysical conceptions of God are meant to resolve the “aporia” of the question “How could something come from nothing?” (that’s not necessarily my view).
Some metaphysical treatments of God posit God as some kind of “absolute entity” that is capable of being its own cause, for example, since, allegedly, something is needed to transcend the issue of “How could something come from nothing?”
I read a good book on this question in high school called “Why Does the World Exist?”
Madeleine Birchfield (Sep 08 2024 at 17:58):Julius Hamilton said:
I’m just engaging with you in conversation rather than seeking to rebut you; I think some would argue that metaphysical conceptions of God are meant to resolve the “aporia” of the question “How could something come from nothing?”
The question “How could something come from nothing?” presumes that there used to be a finite time in the past where there was nothing. It could also simply be the case that there was always something infinitely far back in time, meaning that something never came from nothing.
Julius Hamilton (Sep 08 2024 at 18:18):I personally think the most interesting part of the question is what the nature of “causation” is. Here are some good resources on that topic:
https://plato.stanford.edu/entries/causation-metaphysics/
https://academic.oup.com/edited-volume/42621
In my own thinking, I have been using the minimal hypothesis that causation is the same thing as logical implication, except with a time parameter.