### Re: Coherent states of a superposition

```

On Sunday, January 13, 2019 at 4:13:24 AM UTC, agrays...@gmail.com wrote:
>
>
>
> On Saturday, January 12, 2019 at 8:41:23 AM UTC, agrays...@gmail.com
> wrote:
>>
>>
>>
>> On Friday, January 11, 2019 at 7:40:13 PM UTC, Brent wrote:
>>>
>>>
>>>
>>> On 1/11/2019 1:54 AM, agrays...@gmail.com wrote:
>>>
>>>
>>> *How can you prepare a system in any superposition state if you don't
>>> know the phase angles beforehand? You fail to distinguish measuring or
>>> assuming the phase angles from calculating them. One doesn't need Born's
>>> rule to calculate them. Maybe what Bruce meant is that you can never
>>> calculate them, but you can prepare a system with any relative phase
>>> angles. AG *
>>>
>>>
>>> In practice you prepare a "system" (e.g. a photon) in some particular
>>> but unknown phase angle. Then you split the photon, or entangle it with
>>> another photon, so that you have two with definite relative phase angles,
>>> and with the same frequency,  then those two branches of the photon wave
>>> function can interfere, i.e. the photon the interferes with itself as in
>>> the Young's slits experiment.  So you only calculate the relative phase
>>> shift of the two branches of the wf of the photon, which is enough to
>>> define the interference pattern.
>>>
>>> Brent
>>>
>>
>> *Can a photon be split without violating conservation of energy? In any
>> event, I see my error on this issue of phase angles, and will describe it,
>> possibly to show I am not a complete idiot when it comes to QM. Stayed
>> tuned. AG*
>>
>
> *Maybe I spoke too soon. I don't think I've resolved the issue of
> arbitrary phase angles for components of a superposition of states. For
> example, let's say the superposition consists of orthonormal eigenstates,
> each multiplied by a probability amplitude. If each component is multiplied
> by some arbitrary complex number representing a new phase angle, the
> probability of *measuring* the eigenvalue corresponding to each component
> doesn't change due to the orthonormality (taking the inner product of the
> sum or wf, and then its norm squared). But what does apparently change is
> the probability *density* distribution along the screen, say for double
> slit experiment. But the eigenvalue probabilities which don't change with
> an arbitrary change in phase angle, represent positions along the screen
> via the inner product, DO seem to *shift* in value -- that is, the new
> phases have the effect of changing the probability *density* -- and this
> fact. if it is a fact, contradicts my earlier conclusion that changing the
> relative phase angles does NOT change the calculated probability occurrence
> for each eigenvalue. Is it understandable what my issue is here? TIA, AG*
>

*IOW, if I change the phase angles, the interference changes and therefore
the probability density changes, but this seems to contradict the fact that
changing the phase angles has no effect on the probability of occurrences
of the measured eigenvalues. AG *

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### Re: Coherent states of a superposition

```

On Saturday, January 12, 2019 at 8:41:23 AM UTC, agrays...@gmail.com wrote:
>
>
>
> On Friday, January 11, 2019 at 7:40:13 PM UTC, Brent wrote:
>>
>>
>>
>> On 1/11/2019 1:54 AM, agrays...@gmail.com wrote:
>>
>>
>> *How can you prepare a system in any superposition state if you don't
>> know the phase angles beforehand? You fail to distinguish measuring or
>> assuming the phase angles from calculating them. One doesn't need Born's
>> rule to calculate them. Maybe what Bruce meant is that you can never
>> calculate them, but you can prepare a system with any relative phase
>> angles. AG *
>>
>>
>> In practice you prepare a "system" (e.g. a photon) in some particular but
>> unknown phase angle. Then you split the photon, or entangle it with another
>> photon, so that you have two with definite relative phase angles, and with
>> the same frequency,  then those two branches of the photon wave function
>> can interfere, i.e. the photon the interferes with itself as in the Young's
>> slits experiment.  So you only calculate the relative phase shift of the
>> two branches of the wf of the photon, which is enough to define the
>> interference pattern.
>>
>> Brent
>>
>
> *Can a photon be split without violating conservation of energy? In any
> event, I see my error on this issue of phase angles, and will describe it,
> possibly to show I am not a complete idiot when it comes to QM. Stayed
> tuned. AG*
>

*Maybe I spoke too soon. I don't think I've resolved the issue of arbitrary
phase angles for components of a superposition of states. For example,
let's say the superposition consists of orthonormal eigenstates, each
multiplied by a probability amplitude. If each component is multiplied by
some arbitrary complex number representing a new phase angle, the
probability of *measuring* the eigenvalue corresponding to each component
doesn't change due to the orthonormality (taking the inner product of the
sum or wf, and then its norm squared). But what does apparently change is
the probability *density* distribution along the screen, say for double
slit experiment. But the eigenvalue probabilities which don't change with
an arbitrary change in phase angle, represent positions along the screen
via the inner product, DO seem to *shift* in value -- that is, the new
phases have the effect of changing the probability *density* -- and this
fact. if it is a fact, contradicts my earlier conclusion that changing the
relative phase angles does NOT change the calculated probability occurrence
for each eigenvalue. Is it understandable what my issue is here? TIA, AG*

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### Re: What is comparable and incomparable between casually disconnected universes?

```On Saturday, January 12, 2019 at 4:17:56 PM UTC-6, Brent wrote:
>
>
>
> On 1/12/2019 2:51 AM, Philip Thrift wrote:
>
>
>
> On Friday, January 11, 2019 at 7:19:06 PM UTC-6, Brent wrote:
>>
>>
>>
>> On 1/11/2019 1:57 PM, Philip Thrift wrote:
>>
>>
>>
>> On Friday, January 11, 2019 at 2:46:35 PM UTC-6, Brent wrote:
>>>
>>>
>>>
>>> On 1/11/2019 6:01 AM, John Clark wrote:
>>>
>>> On Thu, Jan 10, 2019 at 8:18 PM Brent Meeker
>>> wrote:
>>>
>>> * > The fine structure constant is e^2/hbar*c.  Those three values are
measured independent of any Feynman diagrams*

>>>
>>> Absolutely correct. So if you use Feynman diagrams to predict what some
>>> physical system is going to do, such as a physical system of 2 electrons
>>> being hit by a photon of light with a wavelength small enough to contain
>>> enough energy to prevent the electrons repulsion, then you'd better get a
>>> number very close to the Fine Structure Constant. If you don't then Feynman
>>> Diagrams aren't any good.
>>>
>>> They didn't use 12,672 Feynman Diagrams because they wanted to know
>>> what the Fine Structure Constant was, they already knew what that
>>> number was to many decimal places from exparament, they used 12,672
>>> Feynman Diagrams because they wanted to see if Feynman Diagrams worked.
>>> And it turned out they worked spectacularly well in that situation, and
>>> that gives scientists great confidence they can use Feynman Diagrams in
>>> other situations to calculate what other physical systems will do that
>>> involve the Electromagnetic Force.
>>>
>>>
>>> There's always an interplay between theory and experiment.  It's
>>> completely analogous to Maxwell's discovery that light is EM waves. There
>>> were already experimental values of the permittivity and permeability of
>>> the vacuum and there were values for the speed of light.  Maxwell showed
>>> that his theory of EM predicted waves and using the permittivity and
>>> permeability values the speed of the waves matched that of light.  Now the
>>> speed of light is a defined constant and so are the permittivity and
>>> permeability of the vacuum.  So the connecting of the three values by a
>>> theory allows their values to be defined.  In the case of the anomalous
>>> magnetic moment of the electron, hbar and c are already defined constants.
>>> So quantum field theory (for which Feynman diagrams are just a
>>> calculational tool) linked them and e to g.
>>>
>>> Brent
>>>
>>>
>>
>>
>> If Feynman Diagrams (tools) are sufficient (to match experimental data)
>> then Quantum Field Theory can be thrown in the wastebasket.
>>
>>
>> ?? Feynman Diagrams are just a mathematical trick for summing up terms to
>> approximate the propagator of QFT.
>>
>> Brent
>>
>
>
> You just make Feynman Diagrams the fundamental elements of the theory, and
> propagators derived from them.
>
>
> How many diagrams?  The propagator has a clear interpretation as
> connecting the field at x with the field at y.  Feynman showed that his
> diagrams provided a good mnemonic for the infinite number of terms that
> would sum to the propagator.  If you take the diagrams as fundamental you
> then need to specify how many.
>
>
> Just like histories are made fundamental, and Hilbert Spaces are derived
> from them.
>
>
> Hilbert spaces are infinite dimensional vector spaces.  So you have the
> same problem: How many histories?
>
> Brent
>

The number of diagrams grows exponentially. As I recall the QED industry is
up to 12 orders of radiative corrections and renormalization orders. The
number of diagrams to evaluate and sum is in the millions if not billions.
This stuff is done on supercomputers these days. People do not really
evaluate Feynman diagrams, they write computer programs.

LC

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### Re: What is comparable and incomparable between casually disconnected universes?

```

On Saturday, January 12, 2019 at 4:17:56 PM UTC-6, Brent wrote:
>
>
>
> On 1/12/2019 2:51 AM, Philip Thrift wrote:
>
>
>
> On Friday, January 11, 2019 at 7:19:06 PM UTC-6, Brent wrote:
>>
>>
>>
>> On 1/11/2019 1:57 PM, Philip Thrift wrote:
>>
>>
>>
>> On Friday, January 11, 2019 at 2:46:35 PM UTC-6, Brent wrote:
>>>
>>>
>>>
>>> On 1/11/2019 6:01 AM, John Clark wrote:
>>>
>>> On Thu, Jan 10, 2019 at 8:18 PM Brent Meeker
>>> wrote:
>>>
>>> * > The fine structure constant is e^2/hbar*c.  Those three values are
measured independent of any Feynman diagrams*

>>>
>>> Absolutely correct. So if you use Feynman diagrams to predict what some
>>> physical system is going to do, such as a physical system of 2 electrons
>>> being hit by a photon of light with a wavelength small enough to contain
>>> enough energy to prevent the electrons repulsion, then you'd better get a
>>> number very close to the Fine Structure Constant. If you don't then Feynman
>>> Diagrams aren't any good.
>>>
>>> They didn't use 12,672 Feynman Diagrams because they wanted to know
>>> what the Fine Structure Constant was, they already knew what that
>>> number was to many decimal places from exparament, they used 12,672
>>> Feynman Diagrams because they wanted to see if Feynman Diagrams worked.
>>> And it turned out they worked spectacularly well in that situation, and
>>> that gives scientists great confidence they can use Feynman Diagrams in
>>> other situations to calculate what other physical systems will do that
>>> involve the Electromagnetic Force.
>>>
>>>
>>> There's always an interplay between theory and experiment.  It's
>>> completely analogous to Maxwell's discovery that light is EM waves. There
>>> were already experimental values of the permittivity and permeability of
>>> the vacuum and there were values for the speed of light.  Maxwell showed
>>> that his theory of EM predicted waves and using the permittivity and
>>> permeability values the speed of the waves matched that of light.  Now the
>>> speed of light is a defined constant and so are the permittivity and
>>> permeability of the vacuum.  So the connecting of the three values by a
>>> theory allows their values to be defined.  In the case of the anomalous
>>> magnetic moment of the electron, hbar and c are already defined constants.
>>> So quantum field theory (for which Feynman diagrams are just a
>>> calculational tool) linked them and e to g.
>>>
>>> Brent
>>>
>>>
>>
>>
>> If Feynman Diagrams (tools) are sufficient (to match experimental data)
>> then Quantum Field Theory can be thrown in the wastebasket.
>>
>>
>> ?? Feynman Diagrams are just a mathematical trick for summing up terms to
>> approximate the propagator of QFT.
>>
>> Brent
>>
>
>
> You just make Feynman Diagrams the fundamental elements of the theory, and
> propagators derived from them.
>
>
> How many diagrams?  The propagator has a clear interpretation as
> connecting the field at x with the field at y.  Feynman showed that his
> diagrams provided a good mnemonic for the infinite number of terms that
> would sum to the propagator.  If you take the diagrams as fundamental you
> then need to specify how many.
>
>
> Just like histories are made fundamental, and Hilbert Spaces are derived
> from them.
>
>
> Hilbert spaces are infinite dimensional vector spaces.  So you have the
> same problem: How many histories?
>
> Brent
>
>
> https://arxiv.org/abs/1002.0589
>
> Theories do not come from Mount Olympus.
>
> - pt
>
>
As many histories/diagrams as you need. There are supercomputers now.

But what do physicists *really *think is *closer to actual reality*?
Something closer to Histories/Diagrams or to a Hilbert Space. Do some
really think that* in fact*  *material reality is actually an
infinite-dimensional Hilbert Space?*

That is so freaking bizarre, isn't it, when you think about it.

- pt

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### Re: UDA and the origin of physics

```

On Saturday, January 12, 2019 at 4:23:51 PM UTC-6, Brent wrote:
>
>
>
> On 1/12/2019 3:06 AM, Philip Thrift wrote:
>
>
>
> On Friday, January 11, 2019 at 7:25:55 PM UTC-6, Brent wrote:
>>
>>
>>
>> On 1/11/2019 2:36 PM, Philip Thrift wrote:
>> >> Of course there are math professors (Dr. Z at Rutgers) who teach on
>> >> the evils of Platonism. And "Truth" is like God, as Rorty said.
>> >
>> >
>> >
>> >
>> >
>> > That is a good summary of Plato. Hirsschberger sum up Plato by saying
>> > that the God of Plato is Truth. Not the one we make public, but the
>> > one we search.
>> >
>> > Now, all my life I have got the feeling that Plato is dismissed, and
>> > badly seen, notably in opposition to Aristotle. But Aristotle did not
>> > understood Plato, except in a curious passage of the “metaphysics”
>> > where he seems to suddenly got the point, and seems to come back to
>> > Plato without saying (but that is an optimistic reading of Aristotle’s
>> > metaphysics, To be sure I found some scholars who saw that too, like
>> > Gerson.
>> >
>> > That "truth is God" makes sense for a computationalist, because
>> > “truth” when encompassing the description of a machine at its correct
>> > substitution level, is no more definable by that machine. Yes, Truth,
>> > and semantics, is very much like the platonician notion of God. You
>> > force me to agree with Rorty on this!
>> >
>>
>> At the same time Rorty said,"Truth is like God" he was a "strict
>> atheist".  He was also a pragmatist, meaning he thought the measure of
>> truth was solely whether it worked.  So I'd gather that Rorty didn't
>> think that "truth" was very useful idea; which is confirmed by him being
>> called an "ironist" by his friends.
>>
>> Brent
>>
>
> He was called a  "boring" atheist.
>
>
> By Danny Postel.  But from Habermas:
>
> * His colleague Jürgen Habermas's obituary for Rorty points out that
> Rorty's contrasting childhood experiences, such as beautiful orchids versus
> reading a book in his parents' house that defended Leon Trotsky against
> Stalin, created an early interest in philosophy. He describes Rorty as an
> ironist:*
>
> *"Nothing is sacred to Rorty the ironist. Asked at the end of his life
> about the 'holy', the strict atheist answered with words reminiscent of the
> young Hegel: 'My sense of the holy is bound up with the hope that some day
> my remote descendants will live in a global civilization in which love is
> pretty much the only law.'[6]"*
>
> Brent
>
>
>
>
>
> *Danny Postel once wrote that Richard Rorty can be*
> *probably best described as a "boring atheist.” Now, can*
> *we hear anything interesting about religion from a*
> *boring atheist? In the case of Rorty, we surely can, at*
> *least in two respects: a) by reading his papers on religion*
> *we can get a picture of his opinions on the role of*
> *religious experience in the lives of human beings that is*
> *far from trivial; b) by using "redescription” as Rorty’s*
> *most powerful weapon in advancing our intellectual and*
> *moral standards, we can reformulate some of his ideas*
> *as being able to enter a conversation with the kind of*
> *thinking known as postmodern Christianity (or weak*
> *theology being its instance). Rorty’s atheism definitely*
> *does not fall into the same category as the atheism of*
> *Richard Dawkins or Daniel Dennett. Rorty seems to*
> *perfectly understand the broadness of religious*
> *experience and its various contexts, although, for*
> *himself, religion is not a live option. His growing*
> *willingness to enter into debate with religion, as we saw*
> *it in the last several years of his life, is supposedly an*
> *inevitable conclusion of contentions published in his*
> *earlier papers where he called religion a "conversationstopper.” *
> *It may well be the case that religion sometimes*
> *is a conversation-stopper, but as Rorty himself holds, it is *
> *our (philosophers’) responsibility to maintain the*
> *discussion even with these sometimes "unwilling” forms*
> *of discourse. Since we know that when discussion*
> *ceases, other forms of persuasion come into play, we*
> *must make sure it will carry on. *
>
>
>
> *Rorty: On Truth*
>
> - pt
>
>

"*Ironist, *a term coined by Richard Rorty
" (in *Contingency, Irony, and
Solidarity*)

[ https://en.wikipedia.org/wiki/Ironism ]

Rorty was the one saying who the Ironists were!

In *Contingency, Irony, and Solidarity
*, Rorty
argues that Proust , Nietzsche
, Foucault
, Heidegger
```

### Re: Solomonoff induction and mechanism

```

On 1/12/2019 3:12 AM, Philip Thrift wrote:

On Friday, January 11, 2019 at 8:14:14 PM UTC-6, Mason Green wrote:

Solomonoff’s method of induction seems like a good fit for a
mechanist view of things. For instance, it could be used to assign
a relative probability to the universe being generated by a
universal dovetailer: 2^(-K) * m, where K is the Kolmogorov
complexity of the universal dovetailer and m is the measure the
dovetailer assigns to universes like ours.

This formula implies that a (more complex) non-universal
dovetailer might be preferable _if_ it assigned a much higher
measure to universes like ours. Such a dovetailer might, for
instance, output only (or mostly) habitable worlds, instead of
outputting mostly uninhabitable worlds as the standard UD does,
and the higher resulting measure would offset the increased
Kolmogorov complexity.

If we live in a highly “atypical” universe, that might also affect
how we should do Solomonoff induction. For instance if we knew
that we lived in a universe with much less suffering than an
“average” inhabited universe, that could imply we were generated
by a dovetailer that doesn’t like suffering. If the opposite is
true and we live in a “mean world”, that means we might be
generated by a sadistic dovetailer, etc.

Generating universes without any emotion (taken widely) possible is
sort of like "Invasion of the Body Snatchers".

A universe without emotion is logically consistent; but it's the same as
a universe without life, which is highly unlikely.

Brent

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### Re: UDA and the origin of physics

```

On 1/12/2019 3:06 AM, Philip Thrift wrote:

On Friday, January 11, 2019 at 7:25:55 PM UTC-6, Brent wrote:

On 1/11/2019 2:36 PM, Philip Thrift wrote:
>> Of course there are math professors (Dr. Z at Rutgers) who
teach on
>> the evils of Platonism. And "Truth" is like God, as Rorty said.
>
>
>
>
>
> That is a good summary of Plato. Hirsschberger sum up Plato by
saying
> that the God of Plato is Truth. Not the one we make public, but the
> one we search.
>
> Now, all my life I have got the feeling that Plato is dismissed,
and
> badly seen, notably in opposition to Aristotle. But Aristotle
did not
> understood Plato, except in a curious passage of the “metaphysics”
> where he seems to suddenly got the point, and seems to come back to
> Plato without saying (but that is an optimistic reading of
Aristotle’s
> metaphysics, To be sure I found some scholars who saw that too,
like
> Gerson.
>
> That "truth is God" makes sense for a computationalist, because
> “truth” when encompassing the description of a machine at its
correct
> substitution level, is no more definable by that machine. Yes,
Truth,
> and semantics, is very much like the platonician notion of God. You
> force me to agree with Rorty on this!
>

At the same time Rorty said,"Truth is like God" he was a "strict
atheist".  He was also a pragmatist, meaning he thought the
measure of
truth was solely whether it worked.  So I'd gather that Rorty didn't
think that "truth" was very useful idea; which is confirmed by him
being
called an "ironist" by his friends.

Brent

He was called a  "boring" atheist.

By Danny Postel.  But from Habermas:/

His colleague Jürgen Habermas's obituary for Rorty points out that
Rorty's contrasting childhood experiences, such as beautiful orchids
versus reading a book in his parents' house that defended Leon Trotsky
against Stalin, created an early interest in philosophy. He describes
Rorty as an ironist://

//
//"Nothing is sacred to Rorty the ironist. Asked at the end of his life
the young Hegel: 'My sense of the holy is bound up with the hope that
some day my remote descendants will live in a global civilization in
which love is pretty much the only law.'[6]"/

Brent

/Danny Postel once wrote that Richard Rorty can be/
/probably best described as a *"boring atheist.”* Now, can/
/we hear anything interesting about religion from a/
/boring atheist? In the case of Rorty, we surely can, at/
/least in two respects: a) by reading his papers on religion/
/we can get a picture of his opinions on the role of/
/religious experience in the lives of human beings that is/
/far from trivial; b) by using "redescription” as Rorty’s/
/most powerful weapon in advancing our intellectual and/
/moral standards, we can reformulate some of his ideas/
/as being able to enter a conversation with the kind of/
/thinking known as postmodern Christianity (or weak/
/theology being its instance). Rorty’s atheism definitely/
/does not fall into the same category as the atheism of/
/Richard Dawkins or Daniel Dennett. Rorty seems to/
/perfectly understand the broadness of religious/
/experience and its various contexts, although, for/
/himself, religion is not a live option. His growing/
/willingness to enter into debate with religion, as we saw/
/it in the last several years of his life, is supposedly an/
/inevitable conclusion of contentions published in his/
/earlier papers where he called religion a "conversationstopper.” /
/It may well be the case that religion sometimes/
/is a conversation-stopper, but as Rorty himself holds, it is /
/our (philosophers’) responsibility to maintain the/
/discussion even with these sometimes "unwilling” forms/
/of discourse. Since we know that when discussion/
/ceases, other forms of persuasion come into play, we/
/must make sure it will carry on. /
/
/

*Rorty: On Truth*

- pt

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.
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.

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### Re: What is comparable and incomparable between casually disconnected universes?

```

On 1/12/2019 2:51 AM, Philip Thrift wrote:

On Friday, January 11, 2019 at 7:19:06 PM UTC-6, Brent wrote:

On 1/11/2019 1:57 PM, Philip Thrift wrote:

On Friday, January 11, 2019 at 2:46:35 PM UTC-6, Brent wrote:

On 1/11/2019 6:01 AM, John Clark wrote:

On Thu, Jan 10, 2019 at 8:18 PM Brent Meeker
wrote:

/> The fine structure constant is e^2/hbar*c.  Those
three values are measured independent of any Feynman
diagrams/

Absolutely correct. So if you use Feynman diagrams to
predict what some physical system is going to do, such as a
physical system of 2 electrons being hit by a photon of
light with a wavelength small enough to contain enough
energy to prevent the electrons repulsion, then you'd better
get a number very close to the Fine Structure Constant. If
you don't then Feynman Diagrams aren't any good.

They didn't use 12,672 Feynman Diagramsbecause they wanted
to know what the Fine Structure Constantwas, they already
knew what that number was to many decimal places from
exparament, they used 12,672 Feynman Diagramsbecause they
wanted to see if Feynman Diagrams worked. And it turned out
they worked spectacularly well in that situation, and that
gives scientists great confidence they can use Feynman
Diagrams in other situations to calculate what other
physical systems will do that involve the Electromagnetic Force.

There's always an interplay between theory and experiment.
It's completely analogous to Maxwell's discovery that light
is EM waves. There were already experimental values of the
permittivity and permeability of the vacuum and there were
values for the speed of light.  Maxwell showed that his
theory of EM predicted waves and using the permittivity and
permeability values the speed of the waves matched that of
light.  Now the speed of light is a defined constant and so
are the permittivity and permeability of the vacuum.  So the
connecting of the three values by a theory allows their
values to be defined.  In the case of the anomalous magnetic
moment of the electron, hbar and c are already defined
constants.  So quantum field theory (for which Feynman
diagrams are just a calculational tool) linked them and e to g.

Brent

If Feynman Diagrams (tools) are sufficient (to match experimental
data) then Quantum Field Theory can be thrown in the wastebasket.

?? Feynman Diagrams are just a mathematical trick for summing up
terms to approximate the propagator of QFT.

Brent

You just make Feynman Diagrams the fundamental elements of the theory,
and propagators derived from them.

How many diagrams?  The propagator has a clear interpretation as
connecting the field at x with the field at y.  Feynman showed that his
diagrams provided a good mnemonic for the infinite number of terms that
would sum to the propagator.  If you take the diagrams as fundamental
you then need to specify how many.

Just like histories are made fundamental, and Hilbert Spaces are
derived from them.

Hilbert spaces are infinite dimensional vector spaces.  So you have the
same problem: How many histories?

Brent

https://arxiv.org/abs/1002.0589

Theories do not come from Mount Olympus.

- pt
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.
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```

### Re: What is comparable and incomparable between casually disconnected universes?

```On Fri, Jan 11, 2019 at 4:57 PM Philip Thrift  wrote:

*> If Feynman Diagrams (tools) are sufficient (to match experimental data)
> then Quantum Field Theory can be thrown in the wastebasket.*
>

You don't have to use Feynman Diagrams, you can think about things the way
Julian Schwinger did and get the same correct answer; but a calculation
that might take Schwinger a month to do Feynman could do in a hour or so with
his diagrams. Both methods are mathematically consistent but neither gives
us a strong intuition why those troublesome physical infinities go away,
all we know is that they do and they give the right answer, aka they agree
with experiment.
John K Clark

>
>

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### Re: What is comparable and incomparable between casually disconnected universes?

```On Fri, Jan 11, 2019 at 5:29 PM Lawrence Crowell <
goldenfieldquaterni...@gmail.com> wrote:

> *Everyone seems to be overlooking charge renormalization.*
>

I didn't. I said before Feynman you got ridiculous answers when you tried
to calculate, like infinite mass/energy for the electron and probabilities
that don't add up to 1. I also said even though it gave sensible answers
that agreed with exparament and even though he could explain why it worked
mathematically he felt that he had just swept the problem under the rug
because he couldn't explain why it worked physically.  Maybe he was being
too self critical, maybe not.

John K Clark

>
>

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### Re: Solomonoff induction and mechanism

```

On Friday, January 11, 2019 at 8:14:14 PM UTC-6, Mason Green wrote:
>
> Solomonoff’s method of induction seems like a good fit for a mechanist
> view of things. For instance, it could be used to assign a relative
> probability to the universe being generated by a universal dovetailer:
> 2^(-K) * m, where K is the Kolmogorov complexity of the universal
> dovetailer and m is the measure the dovetailer assigns to universes like
> ours.
>
> This formula implies that a (more complex) non-universal dovetailer might
> be preferable _if_ it assigned a much higher measure to universes like
> ours. Such a dovetailer might, for instance, output only (or mostly)
> habitable worlds, instead of outputting mostly uninhabitable worlds as the
> standard UD does, and the higher resulting measure would offset the
> increased Kolmogorov complexity.
>
> If we live in a highly “atypical” universe, that might also affect how we
> should do Solomonoff induction. For instance if we knew that we lived in a
> universe with much less suffering than an “average” inhabited universe,
> that could imply we were generated by a dovetailer that doesn’t like
> suffering. If the opposite is true and we live in a “mean world”, that
> means we might be generated by a sadistic dovetailer, etc.

Generating universes without any emotion (taken widely) possible is sort of
like "Invasion of the Body Snatchers".

- pt

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### Re: UDA and the origin of physics

```

On Friday, January 11, 2019 at 7:25:55 PM UTC-6, Brent wrote:
>
>
>
> On 1/11/2019 2:36 PM, Philip Thrift wrote:
> >> Of course there are math professors (Dr. Z at Rutgers) who teach on
> >> the evils of Platonism. And "Truth" is like God, as Rorty said.
> >
> >
> >
> >
> >
> > That is a good summary of Plato. Hirsschberger sum up Plato by saying
> > that the God of Plato is Truth. Not the one we make public, but the
> > one we search.
> >
> > Now, all my life I have got the feeling that Plato is dismissed, and
> > badly seen, notably in opposition to Aristotle. But Aristotle did not
> > understood Plato, except in a curious passage of the “metaphysics”
> > where he seems to suddenly got the point, and seems to come back to
> > Plato without saying (but that is an optimistic reading of Aristotle’s
> > metaphysics, To be sure I found some scholars who saw that too, like
> > Gerson.
> >
> > That "truth is God" makes sense for a computationalist, because
> > “truth” when encompassing the description of a machine at its correct
> > substitution level, is no more definable by that machine. Yes, Truth,
> > and semantics, is very much like the platonician notion of God. You
> > force me to agree with Rorty on this!
> >
>
> At the same time Rorty said,"Truth is like God" he was a "strict
> atheist".  He was also a pragmatist, meaning he thought the measure of
> truth was solely whether it worked.  So I'd gather that Rorty didn't
> think that "truth" was very useful idea; which is confirmed by him being
> called an "ironist" by his friends.
>
> Brent
>

He was called a  "boring" atheist.

*Danny Postel once wrote that Richard Rorty can be*
*probably best described as a "boring atheist.” Now, can*
*we hear anything interesting about religion from a*
*boring atheist? In the case of Rorty, we surely can, at*
*least in two respects: a) by reading his papers on religion*
*we can get a picture of his opinions on the role of*
*religious experience in the lives of human beings that is*
*far from trivial; b) by using "redescription” as Rorty’s*
*most powerful weapon in advancing our intellectual and*
*moral standards, we can reformulate some of his ideas*
*as being able to enter a conversation with the kind of*
*thinking known as postmodern Christianity (or weak*
*theology being its instance). Rorty’s atheism definitely*
*does not fall into the same category as the atheism of*
*Richard Dawkins or Daniel Dennett. Rorty seems to*
*perfectly understand the broadness of religious*
*experience and its various contexts, although, for*
*himself, religion is not a live option. His growing*
*willingness to enter into debate with religion, as we saw*
*it in the last several years of his life, is supposedly an*
*inevitable conclusion of contentions published in his*
*earlier papers where he called religion a "conversationstopper.” *
*It may well be the case that religion sometimes*
*is a conversation-stopper, but as Rorty himself holds, it is *
*our (philosophers’) responsibility to maintain the*
*discussion even with these sometimes "unwilling” forms*
*of discourse. Since we know that when discussion*
*ceases, other forms of persuasion come into play, we*
*must make sure it will carry on. *

*Rorty: On Truth*

- pt

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### Re: What is comparable and incomparable between casually disconnected universes?

```

On Friday, January 11, 2019 at 7:19:06 PM UTC-6, Brent wrote:
>
>
>
> On 1/11/2019 1:57 PM, Philip Thrift wrote:
>
>
>
> On Friday, January 11, 2019 at 2:46:35 PM UTC-6, Brent wrote:
>>
>>
>>
>> On 1/11/2019 6:01 AM, John Clark wrote:
>>
>> On Thu, Jan 10, 2019 at 8:18 PM Brent Meeker  wrote:
>>
>> * > The fine structure constant is e^2/hbar*c.  Those three values are
>>> measured independent of any Feynman diagrams*
>>>
>>
>> Absolutely correct. So if you use Feynman diagrams to predict what some
>> physical system is going to do, such as a physical system of 2 electrons
>> being hit by a photon of light with a wavelength small enough to contain
>> enough energy to prevent the electrons repulsion, then you'd better get a
>> number very close to the Fine Structure Constant. If you don't then Feynman
>> Diagrams aren't any good.
>>
>> They didn't use 12,672 Feynman Diagrams because they wanted to know what
>> the Fine Structure Constant was, they already knew what that number was
>> to many decimal places from exparament, they used 12,672 Feynman Diagrams
>> because they wanted to see if Feynman Diagrams worked. And it turned out
>> they worked spectacularly well in that situation, and that gives scientists
>> great confidence they can use Feynman Diagrams in other situations to
>> calculate what other physical systems will do that involve the
>> Electromagnetic Force.
>>
>>
>> There's always an interplay between theory and experiment.  It's
>> completely analogous to Maxwell's discovery that light is EM waves. There
>> were already experimental values of the permittivity and permeability of
>> the vacuum and there were values for the speed of light.  Maxwell showed
>> that his theory of EM predicted waves and using the permittivity and
>> permeability values the speed of the waves matched that of light.  Now the
>> speed of light is a defined constant and so are the permittivity and
>> permeability of the vacuum.  So the connecting of the three values by a
>> theory allows their values to be defined.  In the case of the anomalous
>> magnetic moment of the electron, hbar and c are already defined constants.
>> So quantum field theory (for which Feynman diagrams are just a
>> calculational tool) linked them and e to g.
>>
>> Brent
>>
>>
>
>
> If Feynman Diagrams (tools) are sufficient (to match experimental data)
> then Quantum Field Theory can be thrown in the wastebasket.
>
>
> ?? Feynman Diagrams are just a mathematical trick for summing up terms to
> approximate the propagator of QFT.
>
> Brent
>

You just make Feynman Diagrams the fundamental elements of the theory, and
propagators derived from them.

Just like histories are made fundamental, and Hilbert Spaces are derived
from them.

https://arxiv.org/abs/1002.0589

Theories do not come from Mount Olympus.

- pt

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### Re: Coherent states of a superposition

```

On Friday, January 11, 2019 at 7:40:13 PM UTC, Brent wrote:
>
>
>
> On 1/11/2019 1:54 AM, agrays...@gmail.com  wrote:
>
>
> *How can you prepare a system in any superposition state if you don't know
> the phase angles beforehand? You fail to distinguish measuring or assuming
> the phase angles from calculating them. One doesn't need Born's rule to
> calculate them. Maybe what Bruce meant is that you can never calculate
> them, but you can prepare a system with any relative phase angles. AG *
>
>
> In practice you prepare a "system" (e.g. a photon) in some particular but
> unknown phase angle. Then you split the photon, or entangle it with another
> photon, so that you have two with definite relative phase angles, and with
> the same frequency,  then those two branches of the photon wave function
> can interfere, i.e. the photon the interferes with itself as in the Young's
> slits experiment.  So you only calculate the relative phase shift of the
> two branches of the wf of the photon, which is enough to define the
> interference pattern.
>
> Brent
>

*Can a photon be split without violating conservation of energy? In any
event, I see my error on this issue of phase angles, and will describe it,
possibly to show I am not a complete idiot when it comes to QM. Stayed
tuned. AG*

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