On Thu, Dec 20, 2018 at 8:22 PM Bruce Kellett <[email protected]> wrote:
> On Fri, Dec 21, 2018 at 1:03 PM Jason Resch <[email protected]> wrote: > >> On Thu, Dec 20, 2018 at 7:05 PM Bruce Kellett <[email protected]> >> wrote: >> >>> On Fri, Dec 21, 2018 at 11:45 AM Jason Resch <[email protected]> >>> wrote: >>> >>>> 1. It is a prediction of eternal inflation and string theory. >>>> >>> >>> String theory and its "landscape" are very speculative, and unlikely to >>> have any relation to the real world -- there is no evidence that string >>> theory is even a coherent theory! Eternal inflation, although popular, is >>> only one possibility for inflation, and even inflationary theory itself is >>> not well-established science. >>> >> >> I agree they are speculative, but they are on the side many many >> universes. >> Meanwhile there is no evidence for "the only universe that exists is the >> one I can see". >> > > The universe we see is the only one for which we have any concrete > evidence, and that evidence is indubitable. > > That's not evidence towards this being the only thing that exists. > >> 2. There is no known principal that prohibits other systems ruled by >>>> different laws. >>>> >>> >>> The idea that everything that is not forbidden must exist is a silly >>> metaphysical notion. >>> >>> >> That's not the position I was advocating, though I think that notion is >> less silly than the idea that we should expect to be in a position to see >> everything that exists. >> > > Why? That is, in fact, all we have any direct evidence for. > We have no evidence nor reason to presume that we should be in a position to see everything that exists. In fact, we already know that not to be the case. We know we can't see what lays beyond the cosmological horizon, for example. As to why I think there are likely many other universes with different laws, I have many separate reasons, and they all point in the same direction: 1. The trend of science has always been to humble humanity by showing us what exists is much larger than we assumed. (Out planet is one of many, our star is one of many, our galaxy is one of many, our Hubble volume is one of many, etc.) 2. It's suggested by our leading cosmological theory (eternal inflation is part of the standard model of cosmology, it is the default theory/assumption in that field of science) 3. It's suggested by the only theories we have that are compatible with QM and gravity 4. It explains the apparent fine tuning without resorting to intelligent design or fantastic luck 5. Multi-verse theories are often simpler than those that constrain possibility 6. It addresses the Wheeler question "Why these laws, not others" 7. There are many other perfectly sound and consistent equations (e.g. one where the gravitational constantly is a different value) why should this particular value for that free parameter be the only one to be "realized" 8. It's a conclusion of arithmetical realism > >> >> 3. The digits of the dimensionless constants at significance levels not >>>> important to life appear to be randomly distributed >>>> >>> >>> Appearances can be deceptive -- vide flat earth. >>> >>> >> >> What do you think determines the dimensionless constants? >> > > They may not be determined by some theory. Or they may be determined by > some TOE. Who knows? > Exactly! > > >> >> 4. It is highly surprising that the dimensionless constants hold the >>>> values they do as if they were even slightly different, the universe would >>>> be too simple for any life to exist >>>> >>> >>> How do you know that? >>> >>> >> It is difficult to create systems that develop spontaneous complexity, as >> any programmer could tell you. That our universe is such a system is >> surprising, given that most systems do not yield spontaneous complexity. >> >> >>> Look, the Bayesian prior for any argument about the nature of the >>> universe is that we exist. So there is nothing in the least surprising >>> about the fact that the universe we observe is compatible with our >>> existence. Anything else is just idle speculation. >>> >> >> But that's not the correct prior to use. >> > > It is, you know. If you did not exist you could not be arguing about this. > So your existence must be part of any prior about the nature of the > universe we see. The prior must include total evidence available. > > >> Your assumption is that one and only one universe exists. >> > > That is all we have evidence for, but it is not so much an assumption as a > well-founded conclusion. > How is this a conclusion of anything? You haven't presented any evidence to this, yet you hold it as a well-founded conclusion. > > >> Starting from that assumption you must then ask what is the probability >> that life will exist in that one and only one universe. Given that the >> probability is low, would suggest the initial assumption is wrong. Of the >> 26 dimensionless constants, lets say each one had a 50/50 chance of leading >> to catastrophe (no life) if in an invalid range. Then the probability that >> all constants would be in the correct range is (1/2)^26 = 1 in 67 million. >> We should then be (1 - (1/2)^26) sure that the universe we can see is not >> the only one. >> > > That is fallacious reasoning, since we do not have any evidence that the > parameters were selected randomly from unknown distributions. > In either case, there is no escape from it, because if they are dependent on something else, you would have to consider what are the odds that the this more fundamental principle is the one thing that exists and it only allows all of these free parameters to only be in a certain range that allows for complex life to spontaneously emerge. > > Why do you believe there is only one inevitable possibility for the laws >>>> of physics? I've never heard any justification for that idea. >>>> >>> >>> Why do you think I believe that? >>> >> >> You seemed to reject the idea of other possible physical systems ruled by >> different laws, and that the dimensionless constants are not from some >> random distribution. >> > > I reject these notions because there is no evidence for them. > But you don't reject the notion that this is the only universe. (Despite there being no evidence for that) > And if you assume this, it does not actually answer any questions, since > you know that the universe in which you exist must be compatible with your > existence. > > The prior for "I will find myself in a universe compatible with my existence" is 100%. I grant you. But the prior you describe is not for this statement, but for "I will find myself in a universe compatible with my existence AND this is the only universe that exists" My argument is the prior for that second statement is far lower than 100%, and I believe it to be very close to zero given the fine tuning coincidence. > > >> One idea about the end-point of physics is that there is a TOE that will >>> explain everything -- predict the values of all constants and so on, maybe >>> even specify a lot of the boundary conditions. Why do you believe that such >>> a TOE is not possible? >>> >> >> I realize that is the dream of many physicists, but science has provided >> no justification for the success that initiative, and substantial evidence >> that such an initiative is doomed to fail (e.g., all the evidence of >> landscapes). >> > > There is actually no evidence for landscapes. These occur only in some > speculative, unevidenced theories. > > Which is not a lot of reason to believe them, I agree. But it is more than exists on the side of "this is the only universe that exists". Jason -- 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 post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
