On Fri, Oct 23, 2020 at 9:24 PM 'Brent Meeker' via Everything List < [email protected]> wrote:
> > > On 10/23/2020 3:52 PM, Jason Resch wrote: > > > > On Fri, Oct 23, 2020 at 4:54 PM 'Brent Meeker' via Everything List < > [email protected]> wrote: > >> >> >> On 10/23/2020 8:15 AM, Jason Resch wrote: >> >> >> >> On Tue, Oct 20, 2020 at 4:37 PM 'Brent Meeker' via Everything List < >> [email protected]> wrote: >> >>> >>> >>> On 10/20/2020 1:20 PM, Jason Resch wrote: >>> >>> >>> >>> On Tue, Oct 20, 2020 at 1:23 PM 'Brent Meeker' via Everything List < >>> [email protected]> wrote: >>> >>>> >>>> >>>> On 10/20/2020 5:39 AM, Bruno Marchal wrote: >>>> >>>> >>>> On 15 Oct 2020, at 20:56, 'Brent Meeker' via Everything List < >>>> [email protected]> wrote: >>>> >>>> You should have read Vic Stenger's "The Fallacy of Fine Tuning". Vic >>>> points out how many examples of fine tuning are mis-conceived...including >>>> Hoyle's prediction of an excited state of carbon. Vic also points out the >>>> fallacy of just considering one parameter when the parameter space is high >>>> dimensional. >>>> >>>> But my general criticism of fine-tuning is two-fold. First, the >>>> concept is not well defined. There is no apriori probability distribution >>>> over possible values. If the possible values are infinite, then any >>>> realized value is improbable. >>>> >>>> >>>> >>>> I don’t think so. That is why Kolmogorov defines a measure space by >>>> forbidding infinite intersection of events. In the finite case the space of >>>> events is the complete boolean structure coming from the subset of the set >>>> of the possible results. In the infinite domain, the measure space os >>>> defined by a strict subset. I miss perhaps something, but the axiomatic of >>>> Kolmogorov has been invented to solve that “infinite number of value” >>>> problem. >>>> >>>> >>>> That's a non-answer. I was just using infinite (as physicists do) to >>>> mean bigger than anything we're thinking of. Kolmogorov just shaped his >>>> definition to make the mathematics simpler. There's nothing in Jason's >>>> analyses that defines the variables as finite. Jason just helps jimself to >>>> an intuition that a value between 7.5 and 7.7 is "fine-tuned". He didn't >>>> first justify the finite interval. >>>> >>> >>> I admit as much in the article. For most parameters, we don't understand >>> the range or probability distribution for the constants. >>> >>> >>> Then how can you assert there is fine tuning. Is a value of 20*+*1 >>> qualify? Does it matter whether the possible range was (0,100) or (19,21)? >>> >>> However, see my explanation for the cosmological constant, a value for >>> which the theory can account for the expected range and probability >>> distribution. >>> >>> >>> That's right, there is a theory that tells us something about a range >>> and probability distribution. But it's far from an accepted theory, and >>> might well be wrong. >>> >> >> It comes out of QFT, perhaps our most strongly tested theory in science, >> at least one that offers the most accurate verified prediction in physics. >> >> >> That "comes out of" is very misleading, since it's applying QFT to >> general relativity which is not even a quantum theory. >> > > But the quantum fields (vacuum) are known to gravitate. > > > "Known" how? You can write down a calculation...which give infinity as an > answer. > The Lamb shift <https://en.wikipedia.org/wiki/Lamb_shift>, for instance, is an artifact of vacuum energy. The Lamb shift changes the energy of the electron, which alters the mass of atoms, thereby affecting gravity. > Having arrived at an obviously wrong answer, you can introduce a cutoff > that you guess at based on some dimensional analysis > There is a notion of absolute hot <https://en.wikipedia.org/wiki/Absolute_hot>, which implies that momentum cannot grow unboundedly. > and get an answer that's wrong by 120 orders of magnitude, > It's not wrong by 120 orders of magnitude, it's unexpectedly small by 120 orders of magnitude. Say you had a wheel, marking every number from 0 to 2Pi on a continuous range. And upon rolling it, you get 10^-120. This result is not "wrong" or "impossible", it's as likely as any other result. But a priori, you would not expect to get such a small number. > instead of infinitely. And you then say this shows we know something like > this must be right??? > > I never said it must be right. Only that no known alternative explanation exists for the cosmological constant problem, and that according to QFT, the vacuum energy shouldn't be zero, and is known to not be zero (e.g. casimir effect, lamb shift, and accelerated expansion of the universe, all count as evidence that it is non zero). > > >> The first application of QFT to the problem gave the wrong answer by 120 >> orders of magnitude. >> > > Wrong is the wrong word here. The answer was unexpectedly small by that > many orders of magnitude, but it is still within the range of possibility. > > > Which is exactly what's wrong with the idea of "fine-tuning". The "range > of possibility" is just pulled out of thin air. Suppose life were possible > for 1e-60 ev/m3 to 1e-20 ev/m3. Would that be "fine-tuning" because > (1-e-20 - 1e-60)<<1 or because 30 orders of magnitude is small compared to > infinity. > It depends on the probability distribution of the variable. I think a more objective way to measure fine-tuning is to weigh universes and physical laws by their Kolmogorov complexity <https://en.wikipedia.org/wiki/Kolmogorov_complexity> -- what's the shortest possible description that produces them? The longer the length of the description, the more "tuning" was required to get there, and the rarer such universes are. In our case, Lambda would add ~120 digits to the cost of our universe in terms of additional information required to describe it. If the multiverse is real, we should expect that the Kolmogorov complexity of our universe is not much greater than the minimum for universes that produce conscious life. (Perhaps further weighted in terms of the number of observers each such universe produces). > > > >> I don't know what prediction you're referring to, there have been >> several. Can you cite the paper? >> > > The prediction that the vacuum state contains energy, and that this energy > under QFT is the sum of each of the field energies, some of which may be > positive or negative, and when they are summed, they come out to be 120 > orders of magnitude smaller than the Planck energy (which is the expected > energy level of each field). I don't know of a reference to the paper, but > I've read it was first calculated by Feynman and Wheeler. I also found this > derivation: https://i.imgur.com/m0QhWOv.png > > > This paper <https://arxiv.org/pdf/1906.00986.pdf> gives three citations > [6-8] to accompany this statement, which might also be useful to you: > > > "Nature contains two relative mass scales: the vacuum energy density V ∼ > (10−30MPl) 4 and the weak scale v 2 ∼ (10−17MPl) 2 where v is the Higgs > vacuum expectation value. Their smallness with respect to the Planck scale > MPl = 1.2 1019 GeV is not understood and is considered as ‘unnatural’ in > relativistic quantum field theory, because it seems to require precise > cancellations among much larger contributions. If these cancellations > happen for no fundamental reason, they are ‘unlikely’, in the sense that > summing random order one numbers gives 10^−120 with a ‘probability’ of > about 10^−120." > > > But who says the random number are order 1. > > It's all just fantasizing. > It's using the Planck scale as the upper bound. 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 view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CA%2BBCJUia3S9%2BN7_5pt296hy%2BiCjhqnxRovgfiEvqj_79U4VWPg%40mail.gmail.com.
