> On 22 Jan 2020, at 21:46, 'Brent Meeker' via Everything List > <[email protected]> wrote: > > > > On 1/22/2020 7:40 AM, Bruno Marchal wrote: >> >>> On 19 Jan 2020, at 19:52, 'Brent Meeker' via Everything List >>> <[email protected] >>> <mailto:[email protected]>> wrote: >>> >>> >>> >>> On 1/18/2020 11:58 PM, Alan Grayson wrote: >>>> >>>> >>>> On Sunday, January 19, 2020 at 12:18:54 AM UTC-7, Brent wrote: >>>> >>>> >>>> On 1/18/2020 10:56 PM, Alan Grayson wrote: >>>>> I don't claim anything except that GR has solutions for a cosmos in which >>>>> space is flat and, in that solution, space is infinite and empirically it >>>>> appears that space is flat. >>>>> >>>>> Measurements don't establish it's flat, as I previously argued. And, as >>>>> you previously stated, the sign of k, the parameter in GR intimately >>>>> associated with curvature, is folded into the initial conditions. But >>>>> since the initial conditions are really unknown, or are speculative, you >>>>> can assume initial conditions which satisfy your bias, in this case FLAT. >>>>> AG >>>> >>>> No. It's not an assumption. Empirically the universe appears flat, which >>>> (assuming the FLRW model) implies it was always flat. It is not a >>>> question of assuming an initial condition, it is inferring the initial >>>> condition from present measurements of k. >>>> >>>> This seems to modify what you wrote a few day ago. In any event, >>>> "empirically" means "measurement", and one cannot measure the curvature as >>>> exactly zero, which is what you need to empirically establish flatness. >>>> The measurements are very close to zero, but not zero. AG >>> >>> When you measure something and it is so close to zero as to be >>> indistinguishable from zero, then taking it to be zero is not an assumption. >> >> Locally. > > No. Even taking it to be flat globally is more than an assumption, it is an > inductive inference. I know that as a (deductive) logician you deprecated > inductive inference...nevertheless as Sean Carroll quipped, "All human > knowledge has come from studying the shadows on the cave wall.”
No problem with this. I am an empiricist, and I do not deprecate inductive inference at all. My feeling that Mechanism is an interesting option comes from my study of biology, theory of evolution, etc. But they lead to assumptions only, and indeed science is only assumption/theories. Even the hardly doubtful fact that we have parents is a theory/assumption. Now some theories are more plausible than other theories. Sean Carroll is right, we can only study the shadows on the cave wall, but we can judge plausible the idea that they are only that: shadows of a deeper reality, and not the fundamental reality itself. Bruno > > Brent > >> >> Be careful, you might be cited by some platists! (Those defending that the >> Earth is flat!). >> >> Bruno >> >> >>> >>> Brent >>> >>> -- >>> 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 [email protected] >>> <mailto:[email protected]>. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/everything-list/5E24A55D.7000604%40verizon.net >>> >>> <https://groups.google.com/d/msgid/everything-list/5E24A55D.7000604%40verizon.net?utm_medium=email&utm_source=footer>. >> >> -- >> 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 [email protected] >> <mailto:[email protected]>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/everything-list/9C28952E-AFDD-486F-B298-D98E02F5FD67%40ulb.ac.be >> >> <https://groups.google.com/d/msgid/everything-list/9C28952E-AFDD-486F-B298-D98E02F5FD67%40ulb.ac.be?utm_medium=email&utm_source=footer>. > > > -- > 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 [email protected] > <mailto:[email protected]>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/everything-list/620c66f9-f146-94a6-4f47-fe06b2cef539%40verizon.net > > <https://groups.google.com/d/msgid/everything-list/620c66f9-f146-94a6-4f47-fe06b2cef539%40verizon.net?utm_medium=email&utm_source=footer>. -- 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/A6C28200-B467-4223-AAD7-98A622896E7B%40ulb.ac.be.
