[FRIAM] cosmic underdetermination theorem

[Santafe]

btw, thank you for this.

Like the cosmic horizon, both the top link and the journal article are behind paywalls.  But the university could get me the second one.  A 3-page paper.  Amazing.  I read the construction, and think I follow the claims.  I haven’t spent time looking at the manifolds he constructs, enough to convince myself that I can see them.  But that’s just time.

Eric



> On Jan 29, 2025, at 10:06, glen <gepropella at gmail.com> wrote:
> 
> 
> https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fiai.tv%2farticles%2fthe-universe-is-unknowable-from-within-it-auid-3057&c=E,1,AwRg2KvGth_GUJNej88XfasttX1aPURydaXEN5gmJ6dMKxuwMl3JdpIAkGubWAXi5tfnWlj8tgE1UycYvSgY6FNlCIwxJuhaShCol9rByga_qoOi2vlrfEmGWvAh&typo=1
> 
> "In light of the situation, one might insist that spacetime have certain global properties instead. But what justifies this move? Given the theorem, we know this justification cannot be due to any observational data we have collected -- even after allowing for any local induction on such data. Perhaps one could appeal to some strong form of global induction. For example, the Copernican principle could be invoked which seems to modestly deny us a special status in the cosmos: the observable universe is presumed to be representative of the entirety of spacetime. But as the philosopher John Earman has aptly remarked, "this seeming modesty is belied by the immodest use to which the principle is put in justifying an inductive extrapolation'' [9]. Indeed, induction on such vast scales would seem to be suspect given that we are able to observe only the tiniest fraction of the universe [10]. Remember the ants!"
> 
> 2 of the interesting references are here:
> 
> Manchak, J. (2009), "Can We Know the Global Structure of Spacetime?" Studies in History and Philosophy of Modern Physics, 40: 53-56.
> https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fdoi.org%2f10.1016%2fj.shpsb.2008.07.004&c=E,1,37U3FCfmt2kwwoKkBsYaXr_rchHZnkSAi9xBTqlvvdv028Es-FGPFjYp8EdtMUAU1hhZ5Z1U0wHTkLD1l91G3KQBPW3CsXm9qS9sgXrDdMH_1K1PQzHg_4-6NQ,,&typo=1
> 
> Malament, D. (1977), “Observationally Indistinguishable Space-Times,” in J. Earman, C. Glymour, and J. Stachel (eds.), Foundations of Space-Time Theories, Minnesota Studies in the Philosophy of Science, Volume VIII, Minneapolis: University of Minnesota Press, 61-80.
> https://linkprotect.cudasvc.com/url?a=https%3a%2f%2fdoi.org%2f10.1086%2f288937&c=E,1,Q_uB9n6h8cuxI8PJfJUAUXEneL5kf0t-_7I3B0hD5dKR_BsE-8DV8QnxeWQrawsI-DjEs7bq0UpHjFOtH-Hfxukjcd2VW0D-u4jftuuEbvf7eIngs1-0vXmmLyU,&typo=1
> 
> -- 
> ¡sıɹƎ ןıɐH ⊥ ɐןןǝdoɹ ǝ uǝןƃ
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