Can the Universe Cause Itself to Exist from a Physics Perspective?

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The discussion explores the concept of whether the universe can cause itself to exist from a physics perspective, with participants noting that this topic often veers into philosophical territory. Theories such as quantum fluctuations and the Big Bang are mentioned, suggesting that the universe may have emerged from a prior state, though the specifics remain speculative. The role of dark energy is highlighted, indicating that it complicates traditional models of the universe's fate, including possibilities like a Big Crunch or perpetual expansion. Participants express uncertainty about the origins of the universe and the nature of time before the Big Bang, emphasizing the need for further scientific exploration. Ultimately, the conversation reflects a blend of physics and philosophy, with no definitive answers currently available.
  • #91
Dmitry67 said:
This is impossible
To prove that any mathematical theory is self-consistent, you always need to use more powerful/more complicated theory.
So the whole mathematics is based on the pure belief.
...
Thanks Dmitry67, I realize this now and that we already know that the universe is fully consistent, otherwise lot of weird stuff would happen to us... and the math describing this must therefore be fully consistent.
DevilsAvocado said:
Chalnoth said:
... An inconsistency is an impossibility. ...
Thanks a lot for the explanation. I think I see the light now...

We already know that the universe is fully consistent, otherwise we wouldn’t be here, right? Or we would be here, but a lot of people would get killed on the 'inconsistent highway' everyday – by Boltzmann Brains popping out of nowhere and smashing into their windshields...

So, if we can find a mathematical structure that describes this fully consistent universe, it is okay. And then we would know that the universe is isomorphic to that mathematical structure.
 
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  • #92
Chalnoth said:
No, it really doesn't. The problem is that there's a tension between different definitions of the word, and neither class of definition comes close to solving the problem. The more specific your definition gets, the more complex your God gets, and thus the less it becomes an explanation. The less specific your definition gets, the more meaningless the term God even becomes, and thus it fails as an explanation in the other direction.

Because of this vague slipperiness of the very definition of the word "god", it is an impossibility to ever bring up any evidence for or against, and for that reason the hypothesis simply fails as being too poorly-defined.

Well, we shouldn't be too dismissive of Chronos' view or the "God Hypothesis" since "God" is more of a metaphysical assertion rather than a scientific theory, others who have a naturalistic world view would think God and most metaphysical statements are meaningless, yet as Karl Popper said, they are not meaningless but rather not falsifiable, hence metaphysical statements implies something about the universe that are not empirically testable, but remain epistemically plausible.
 
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  • #93
celebrei said:
... as Karl Popper said, they are not meaningless but rather not falsifiable, hence metaphysical statements implies something about the universe that are not empirically testable, but remain epistemically plausible.


I don’t agree, because scientifically this statement:
"I favor the God hypothesis. It provides a reasonable, albeit incomplete, explanation."
Has the exactly the same significance as this statement:
"I favor the Santa Claus hypothesis. It provides a reasonable, albeit incomplete, explanation."
For those who believe in Santa Claus, even if not empirically testable, Santa remains epistemically plausible.
For science, and those who don’t believe in Santa Claus, this means absolutely nothing.
 
  • #94
Newai said:
I don't see why the universe has to have been created at all...

DaveC426913 said:
Well, our current evidence seems to suggest it was.

Or more to-the-point: our current evidence seems to suggest that, at one time, it wasn't.

I believe that statement is out of line with current expert opinion. There is no scientific reason to believe that the universe did not exist before, say, 13.7 billion years ago, according to the relevant research community.

For example, according to Einstein-Online, a Max Planck Institute public outreach site, most scientists would be surprised if it actually turned out that there was a singularity at the start of expansion. By a singularity I mean a point where time stops as you work back, where there is no "before". The expectation is that time and existence go back before the start of expansion. If you want a non-technical pubic outreach discussion as of 2006, try the E-O essay called "A tale of two big bangs". It is the top google hit if you say "tale of two big bangs". Or use this link:
http://www.aei.mpg.de/einsteinOnline/en/spotlights/big_bangs/index.html

If you want a technical sample of what the research community is actually studying these days ( non-singular models of conditions leading up to the start of expansion) just do a spires search with keyword "quantum cosmology" for papers from 2006 and later.
You can use this link:
http://www.slac.stanford.edu/spires/find/hep/www?rawcmd=dk+quantum+cosmology+and+date%3E2005&FORMAT=WWW&SEQUENCE=citecount%28d%29
or just go to Spires and ask for keyword "quantum cosmology" and date > 2005.

You will see 374 papers, after 2005, studying several different non-singular models of what can have led up to the start of expansion, pursuing several ideas. Some papers proposing ways to test nonsingular models by astrophysical observation--primarily features of the microwave background.

Roger Penrose pointed out in 2005 that there had been a change in conventional scientific opinion, among the relevant expert community. According to a talk he gave at Cambridge, before 2005 it was generally considered meaningless to talk about before-BB (like "what is north of the north pole?") but according to him 2005 was a watershed year when the prevailing scientific opinion changed. Of course some had been working on nonsingular models already for quite some time, but he picked out 2005 as the year that dominant opinion shifted. For what it's worth---just one person's take on a change of fashion in scientific thought.

I set up the Spires search to list in order of citation-count so you get the most cited papers first. All or virtually all of the first hundred or so treat non-singular models----where time and existence go back before the start of expansion.
 
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  • #95
This thread's really slipped under the radar: theological or philosophical discussions are not permitted in the cosmology forum. Thus, this thread is closed.
 

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