On 10/24/2020 5:29 AM, Jason Resch wrote:
On Fri, Oct 23, 2020 at 9:24 PM 'Brent Meeker' via Everything List
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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]
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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]
<mailto:[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]
<mailto:[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]
<mailto:[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.
There's also a sense in which the temperature scale wraps around to
negative values. What does this have to do with anything?
and get an answer that's wrong by 120 orders of magnitude,
It's not wrong by 120 orders of magnitude,
The calculation is wrong because it purports to compute the vacuum
energy density.
it's unexpectedly small by 120 orders of magnitude.
You mean the measured value it small...but not unexpectedly. Most
people expected it to be zero.
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.
A priori you wouldn't expect to get 1.0 either. "Such a small number"
just reflects our convenient naming conventions. Notice that if you had
labelled your wheel 0 to 360 degrees, then "You wouldn't expect to get
such a small number as 1.0".
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?
Any finite law can be described in one word, like "Newton's". Kolmogorov
complexity measure only makes sense for infinite strings.
The longer the length of the description, the more "tuning" was
required to get there, and the rarer such universes are.
Which is essentially assuming what you're trying to argue, i.e. that
there is an infinite ensemble of "everythingism" and "fine-tuning" that
is evidence for it. The trouble is you keep needing to slip in
assumptions equivalent to your conclusions.
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.
So what? That's assuming the Planck scale means something, but it's
already rejected as 'unatural'. You can't have it both ways.
Brent
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