Re: Discrete theories of space.

[John Clark]

On Sun, Jan 20, 2019 at 5:55 PM Philip Thrift  wrote:

> As for LQG's "quantum geometry" being empirical, as I posted before
>
> *Glimpses of Space-Time Beyond the Singularities Using Supercomputers*
> https://arxiv.org/abs/1809.01747
>

I see nothing empirical in that, it's a supercomputer simulation. It's
saying "maybe this is what's going on when things get smaller than the
Planck length", well maybe it is and maybe it isn't. I saw no experiment or
even a proposed  experiment that could tell us. Perhaps someday Loop
Quantum Gravity or String Theory will be able to make a testable prediction but
they're not there yet so until then it's mathematics not physics.

> Why are people so wedded to the traditional spacetime.
>

Because they're wedded to the scientific method.  I asked before how you
could perform an experiment without making use of space or time but
received no answer.

 John K Clark

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Re: Planck Length

[Lawrence Crowell]

On Sunday, January 20, 2019 at 9:16:01 AM UTC-6, Bruno Marchal wrote:
>
>
> On 19 Jan 2019, at 01:42, Lawrence Crowell  > wrote:
>
> On Thursday, January 17, 2019 at 6:31:06 AM UTC-6, Bruno Marchal wrote:
>>
>>
>> On 17 Jan 2019, at 09:22, agrays...@gmail.com wrote:
>>
>>
>>
>> On Monday, January 7, 2019 at 9:25:16 PM UTC, John Clark wrote:
>>>
>>> On Mon, Jan 7, 2019 at 8:03 AM  wrote:
>>>
>>> *> How does one calculate Planck length using the fundamental constants 
 G, h, and c, and having calculated it, how does one show that measuring a 
 length that small with photons of the same approximate wave length, would 
 result in a black hole? TIA, AG*
>>>
>>>  
>>> In any wave the speed of the wave is wavelength times frequency and 
>>> according to 
>>> Planck E= h*frequency  so E= C*h/wavelength.  Thus the smaller the 
>>> wavelength the greater the energy. According to Einstein energy is just 
>>> another form of mass (E = MC^2) so at some point the wavelength is so 
>>> small and the light photon is so energetic (aka massive) that the escape 
>>> velocity is greater than the speed of light and the object becomes a Black 
>>> Hole.
>>>
>>> Or you can look at it another way, we know from Heisenberg that to 
>>> determine the position of a particle more precisely with light you have to 
>>> use a smaller wavelength, and there is something called the  "Compton 
>>> wavelength" (Lc) ; to pin down the position of a particle of mass m to 
>>> within one Compton wavelength would require light of enough energy to 
>>> create another particle of that mass. The formula for the Compton 
>>> Wavelength is Lc= h/(2PI*M*c).
>>>
>>> Schwarzschild told us that the radius of a Black Hole (Rs), that is to 
>>> say where the escape velocity is the speed of light  is:  Rs= GM/c^2. At 
>>> some mass Lc will equal Rs and that mass is the Planck mass, and that Black 
>>> Hole will have the radius of the Planck Length, 1.6*10^-35 meters.
>>>
>>> Then if you do a little algebra: 
>>> GM/c^2 = h/(2PI*M*c)
>>> GM= hc/2PI*M
>>> GM^2 = hc/2*PI
>>> M^2 = hc/2*PI*G
>>> M = (hc/2*PI*G)^1/2and that is the formula for the Planck Mass , 
>>> it's .02 milligrams.
>>>
>>> And the Planck Length turns out to be (G*h/2*PI*c^3)^1/2 and the Planck 
>>> time 
>>> is the time it takes light to travel the Planck length. 
>>>
>>> The Planck Temperature Tp is sort of the counterpoint to Absolute Zero, 
>>> Tp is as hot as things can get because the black-body radiation given off 
>>> by things when they are at temperature Tp have a wavelength equal to the 
>>> Planck Length, the distance light can move in the Planck Time of 10^-44 
>>> seconds. The formula for the Planck temperature is Tp = Mp*c^2/k where Mp 
>>> is the Planck Mass and K is Boltzmann's constant and it works out to be 
>>> 1.4*10^32 degrees Kelvin.  Beyond that point both Quantum Mechanics and 
>>> General Relativity break down and nobody understands what if anything is 
>>> going on.
>>>
>>> The surface temperature of the sun is at 5.7 *10^3  degrees Kelvin so if 
>>> it were 2.46*10^28 times hotter it would be at the Planck Temperature, and 
>>> because radiant energy is proportional to T^4 the sun would be 3.67*10^113 
>>> times brighter. At that temperature to equal the sun's brightness the 
>>> surface area would have to be reduced by a factor of 3.67*10^113, the 
>>> surface area of a sphere is proportional to the radius squared, so you'd 
>>> have to reduce the sun's radius by (3.67*10^113)^1/2, and that is  
>>> 6.05*10^56. 
>>> The sun's radius is 6.95*10^8   meters and  6.95*10^8/ 6.05*10^56  is 
>>> 1.15^10^-48 meters. 
>>>
>>> That means a sphere at the Planck Temperature with a radius 10 thousand 
>>> billion times SMALLER than the Planck Length would be as bright as the sun, 
>>> but as far as we know nothing can be that small. If the radius was 10^13 
>>> times longer it would be as small as things can get and the object would be 
>>> (10^13)^2 = 10^26 times as bright as the sun. I'm just speculating but 
>>> perhaps that's the luminosity of the Big Bang; I say that because that's 
>>> how bright things would be if the smallest thing we think can exist was as 
>>> hot as we think things can get. 
>>>
>>> John K Clark
>>>
>>
>>
>> *Later I'll post some questions I have about your derivation of the 
>> Planck length, but for now here's a philosophical question; Is there any 
>> difference between the claim that space is discrete, from the claim or 
>> conjecture that we cannot in principle measure a length shorter than the 
>> Planck length? *
>> *TIA, AG *
>>
>>
>> That is a very good question. I have no answer. I don’t think physicists 
>> have an answer either, and I do think that this requires the solution of 
>> the “quantum gravity” or the “quantum space-time” problem. 
>> With loop-gravity theory, I would say that the continuum is eventually 
>> replaced by something discrete, but not so with string theory; for example. 
>> With Mechanism, there are a

Re: Discrete theories of space.

[Philip Thrift]

On Sunday, January 20, 2019 at 4:37:35 PM UTC-6, John Clark wrote:
>
> On Sun, Jan 20, 2019 at 4:31 PM Philip Thrift  > wrote:
>   
>
>> *>>> What we call space (x,y,z) is just what we measure with a ruler.*
 *What we call time t is just what we measure with a clock.*

>>>
>>> >>True, and thus space and time have well defined definitions. And 
>>> that's why we can't do experiments without a ruler and a clock, you 
>>> wouldn't know where to look for the results or when to look. Without
>>>  experiment or prediction or even postdiction you're just navel gazing 
>>> not doing physics.
>>>
>>
>> > *I don't understand space and time have well defined definitions.*
>>
>
> it's odd you don't understand that as you give crystal clear definitions 
> yourself, space is what a ruler measures and time is what a clock measures. 
> Zero ambiguity in that. 
>  
>
>> * > If (say) LQG is right, then* []
>>
>
> Then we'll never know it's right without an experiment that can confirm 
> it,  and experiments can't exist without rulers and clocks. 
>
>> > *then all rulers and clocks are are things made of QPSCs.*
>>
>
> So what? Everything is made of something else unless you're at the 
> fundamental level. Space and time may not be made of anything but at least 
> they're measurable, I don't see how claiming the fundamental level is mot 
> made of anything and is not measurable either get's you anywhere; you could 
> theorize it's made of anything you like and it would still be consistent 
> with any conceivable experiment. In other words its just navel gazing.
>
> John k Clark
>
>
>
>
As for LQG's "quantum geometry" being empirical, as I posted before

*Glimpses of Space-Time Beyond the Singularities Using Supercomputers*
https://arxiv.org/abs/1809.01747 

"Numerical studies using HPC reveal the existence of an effective 
space-time description that sheds important light on the way continuum 
space-time emerges from quantum geometry and *potentially links LQG with 
astronomical observations*. In coming years, one challenge is to extend 
these results to inhomogeneous space-times where the understanding of 
analytical aspects in quantum gravity is yet to be completed. Given the 
progress over the past couple of years, it can be expected that 
supercomputers will prove to be an invaluable and essential tool for the 
complete discovery of the new physics at the Planck scale, and to go beyond 
the limitations of Einstein’s GR."


Why are people so wedded to the traditional spacetime.
Is the Immanuel Kant Song right? :)

- pt

>  
>

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Re: Discrete theories of space.

[John Clark]

On Sun, Jan 20, 2019 at 4:31 PM Philip Thrift  wrote:


> *>>> What we call space (x,y,z) is just what we measure with a ruler.*
>>> *What we call time t is just what we measure with a clock.*
>>>
>>
>> >>True, and thus space and time have well defined definitions. And
>> that's why we can't do experiments without a ruler and a clock, you
>> wouldn't know where to look for the results or when to look. Without
>>  experiment or prediction or even postdiction you're just navel gazing
>> not doing physics.
>>
>
> > *I don't understand space and time have well defined definitions.*
>

it's odd you don't understand that as you give crystal clear definitions
yourself, space is what a ruler measures and time is what a clock measures.
Zero ambiguity in that.


> * > If (say) LQG is right, then* []
>

Then we'll never know it's right without an experiment that can confirm it,
 and experiments can't exist without rulers and clocks.

> > *then all rulers and clocks are are things made of QPSCs.*
>

So what? Everything is made of something else unless you're at the
fundamental level. Space and time may not be made of anything but at least
they're measurable, I don't see how claiming the fundamental level is mot
made of anything and is not measurable either get's you anywhere; you could
theorize it's made of anything you like and it would still be consistent
with any conceivable experiment. In other words its just navel gazing.

John k Clark

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Re: Discrete theories of space.

[Philip Thrift]

On Sunday, January 20, 2019 at 2:56:19 PM UTC-6, John Clark wrote:
>
> On Sun, Jan 20, 2019 at 2:03 PM Philip Thrift  > wrote:
>
> >> Experiments involve space and time, if those equations involve neither 
>>> I don't see how you could ever test them to see if they're correct;  and if 
>>> you can't do that then it's not science, it's just philosophy. And 
>>> philosophers have been proven wrong far more often than proven right.
>>>
>>  
>> *> What we call space (x,y,z) is just what we measure with a ruler.*
>> *What we call time t is just what we measure with a clock.*
>>
>
> True, and thus space and time have well defined definitions. And that's 
> why we can't do experiments without a ruler and a clock, you wouldn't know 
> where to look for the results or when to look. Without experiment or 
> prediction or even postdiction you're just navel gazing not doing physics.
>
> John K Clark
>
>
>>
I don't understand space and time have well defined definitions. If (say) 
LQG is right, then all there are are quantum particles and spinfoam cells 
(QPs+SCs=QPSCs) - that's all the stuff there is (spacetime itself is now 
stuff to), then all rulers and clocks are are things made of QPSCs.

- pt

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Re: Discrete theories of space

[agrayson2000]

On Sunday, January 20, 2019 at 3:14:39 PM UTC, Lawrence Crowell wrote:
>
> On Saturday, January 19, 2019 at 5:42:12 AM UTC-6, agrays...@gmail.com 
> wrote:
>>
>> Since it seems conceptually impossible to model a theory with DISJOINT 
>> discrete spatial units, thus requiring the units to be juxtaposed, do such 
>> theories acknowledge difficulty of motion between the units, which might or 
>> might not have boundaries? TIA, AG
>>
>
> I am not sure how to impress people with how bad this thinking is. 
>

*Instead of being rude, why don't you state YOUR definition of DISCRETE in 
the context of DISCRETE space? I speak ENGLISH as a native language.  Do 
you? AG*

These slice and diced chunks of spacetime, whether voxels, plaquettes and 
> so forth have violations of Lorentz symmetry of spacetime. This means that 
> curiously the symmetry of gravitation would be violated at higher energy, 
> and in fact where it is quantized. These ideas have further been falsified 
> by the lack of dispersion from distant sources. These ideas are bad 
> interpretations of the Planck length. The Planck length is just the 
> smallest length beyond which you can isolate a quantum bit. Remember, it is 
> the length at which the Compton wavelength of a black hole equals its 
> Schwarzschild radius. It is a bit similar to the Nyquist frequency in 
> engineering. In order to measure the frequency of a rotating system you 
> must take pictures that are at least double that frequency. Similarly to 
> measure the frequency of an EM wave you need to have a wave with Fourier 
> modes that are 2 or more times the frequency you want to measure. The black 
> hole is in a sense a fundamental cut-off in the time scale, or in a 
> reciprocal manner the energy, one can sample space to find qubits. 
>
> The levels of confusion over this are enormous. It does not tell us that 
> spacetime is somehow sliced and diced into briquets or pieces. It does not 
> tell us that quantum energy of some fields can't be far larger than the 
> Planck energy, or equivalently the wavelength much smaller. This would be 
> analogous to a resonance state, and there is no reason there can't be such 
> a thing in quantum gravity. The Planck scale would suggest this sort of 
> state may decay into a sub-Planckian energy.  Further, it is plausible that 
> quantum gravity beyond what appears as a linearized weak field 
> approximation similar to the QED of photon bunched pairs may only exist at 
> most an order of magnitude larger than the Planck scale anyway. A 
> holographic screen is then a sort of beam splitter at the quantum-classical 
> divide.
>
> LC
>

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Re: Discrete theories of space.

[John Clark]

On Sun, Jan 20, 2019 at 2:03 PM Philip Thrift  wrote:

>> Experiments involve space and time, if those equations involve neither I
>> don't see how you could ever test them to see if they're correct;  and if
>> you can't do that then it's not science, it's just philosophy. And
>> philosophers have been proven wrong far more often than proven right.
>>
>
> *> What we call space (x,y,z) is just what we measure with a ruler.*
> *What we call time t is just what we measure with a clock.*
>

True, and thus space and time have well defined definitions. And that's why
we can't do experiments without a ruler and a clock, you wouldn't know
where to look for the results or when to look. Without experiment or
prediction or even postdiction you're just navel gazing not doing physics.

John K Clark


>

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Re: Discrete theories of space.

[Philip Thrift]

On Sunday, January 20, 2019 at 9:23:09 AM UTC-6, John Clark wrote:
>
> On Saturday, January 19, 2019 at 5:22:25 PM UTC-6, Philip Thrift wrote:
>
> > *T*
>>
>>
>> *his by Carlo Rovelli:> https://arxiv.org/abs/1802.02382 
>> > concludes:> "Notice that nowhere in the 
>> basic equations of the theory a time coordinate t or a space coordinate x 
>> show up**"*.
>
>
> Experiments involve space and time, if those equations involve neither I 
> don't see how you could ever test them to see if they're correct;  and if 
> you can't do that then it's not science, it's just philosophy. And 
> philosophers have been proven wrong far more often than proven right.
>
>  John K Clark
>
>
 

What we call space *(x,y,z)* is just what we measure with a ruler.
What we call time* t* is just what we measure with a clock.

A space measurement = a ruler measurement.
A time measurement = a clock measurement.

That's all we know about space and time.

- pt

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Re: Discrete theories of space

[Philip Thrift]

On Sunday, January 20, 2019 at 9:14:39 AM UTC-6, Lawrence Crowell wrote:
>
> On Saturday, January 19, 2019 at 5:42:12 AM UTC-6, agrays...@gmail.com 
> wrote:
>>
>> Since it seems conceptually impossible to model a theory with DISJOINT 
>> discrete spatial units, thus requiring the units to be juxtaposed, do such 
>> theories acknowledge difficulty of motion between the units, which might or 
>> might not have boundaries? TIA, AG
>>
>
> I am not sure how to impress people with how bad this thinking is. These 
> slice and diced chunks of spacetime, whether voxels, plaquettes and so 
> forth have violations of Lorentz symmetry of spacetime. This means that 
> curiously the symmetry of gravitation would be violated at higher energy, 
> and in fact where it is quantized. These ideas have further been falsified 
> by the lack of dispersion from distant sources. These ideas are bad 
> interpretations of the Planck length. The Planck length is just the 
> smallest length beyond which you can isolate a quantum bit. Remember, it is 
> the length at which the Compton wavelength of a black hole equals its 
> Schwarzschild radius. It is a bit similar to the Nyquist frequency in 
> engineering. In order to measure the frequency of a rotating system you 
> must take pictures that are at least double that frequency. Similarly to 
> measure the frequency of an EM wave you need to have a wave with Fourier 
> modes that are 2 or more times the frequency you want to measure. The black 
> hole is in a sense a fundamental cut-off in the time scale, or in a 
> reciprocal manner the energy, one can sample space to find qubits. 
>
> The levels of confusion over this are enormous. It does not tell us that 
> spacetime is somehow sliced and diced into briquets or pieces. It does not 
> tell us that quantum energy of some fields can't be far larger than the 
> Planck energy, or equivalently the wavelength much smaller. This would be 
> analogous to a resonance state, and there is no reason there can't be such 
> a thing in quantum gravity. The Planck scale would suggest this sort of 
> state may decay into a sub-Planckian energy.  Further, it is plausible that 
> quantum gravity beyond what appears as a linearized weak field 
> approximation similar to the QED of photon bunched pairs may only exist at 
> most an order of magnitude larger than the Planck scale anyway. A 
> holographic screen is then a sort of beam splitter at the quantum-classical 
> divide.
>
> LC
>



Where is the "inconsistency" in the article

*Space and Time in* *Loop Quantum Gravity*
Carlo Rovelli 
https://arxiv.org/abs/1802.02382

Replacing spacetime with spinfoam still has some spin cycles left.

- pt

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Re: UDA and the origin of physics

[Philip Thrift]

On Sunday, January 20, 2019 at 8:52:54 AM UTC-6, Bruno Marchal wrote:
>
>
> On 15 Jan 2019, at 12:56, Philip Thrift > 
> wrote:
>
>
>
> On Tuesday, January 15, 2019 at 5:33:01 AM UTC-6, Bruno Marchal wrote:
>>
>>
>> > On 14 Jan 2019, at 20:27, Brent Meeker  wrote: 
>> > 
>> > 
>> > 
>> > On 1/14/2019 3:22 AM, Bruno Marchal wrote: 
>> >> The physics comes from the first person statistical interference 
>> between those dreams. 
>> > 
>> > Where can this "person" be to make a statisical inference, if there are 
>> only the dreams? 
>> > 
>>
>> That person makes the inference in the dreams, and test them in the mean 
>> (most normal, in the Gaussian sense) consistent extensions where it 
>> consciousness differentiate. 
>>
>> Those dream are not “nocturnal” type of dream. A dream here is just a 
>> computation supporting a Löbian machine, which itself supports a person 
>> ([]p &p). The measure one is given either by []p & p (p sigma_1), or just 
>> []p & <>t. “[]p” alone cannot work, because G adds “cul-de-sac world” at 
>> any transition, and we have to get rid of them, to get the default 
>> hypotheses used in probability or credibility theory. 
>>
>> We do reverse engineering somehow. We extract the geometry of the 
>> universe (the accessibility relations) from the modal logic of the 
>> observable/predictable, which is derived from the “material variants” of G 
>> (mainly Z). 
>>
>> With mechanism, there are no other way, unless adding a magical selection 
>> principle, but that would make impossible to trust any digitalist doctors. 
>> Would you say yes to a doctor who says that the transplant needs some 
>> prayer? 
>>
>> Bruno 
>>
>>
>>
> But what exactly counts as a digital implant?
>
>  Likely, neurosurgeons in the future will be replacing neurons and groups 
> of neurons in human brains with synthetic neurons made of some sort of 
> materials, perhaps including silicon, but also biopolymers …
>
>
>
> An implant can be said digital if it is emulable at the relevant 
> substitution level (that we cannot know for sure, that is why it is a sort 
> of bet).
>
> If the primitive matter plays a role, it has to be non Turing emulable at 
> all, but there are no evidences for this, and some contrary evidences do 
> exist.
>
> Bruno
>
>
>

Suppose you replace one neuron (e.g. w/[OEBN], but something of that kind) 
in a human brain. Everything's fine. The you replace a group of neurons. 
Everything's fine. Eventually all neurons are replaced. Is the result an 
*emulation*?

[OEBN] *An organic electronic biomimetic neuron enables auto-regulated 
neuromodulation*
https://www.sciencedirect.com/science/article/pii/S0956566315300610

Abstract

Current therapies for neurological disorders are based on traditional 
medication and electric stimulation. Here, we present an *organic 
electronic biomimetic neuron*, with the capacity to precisely intervene 
with the underlying malfunctioning signaling pathway using endogenous 
substances. The fundamental function of neurons, defined as 
chemical-to-electrical-to-chemical signal transduction, is achieved by 
connecting enzyme-based amperometric biosensors and organic electronic ion 
pumps. Selective biosensors transduce chemical signals into an electric 
current, which regulates electrophoretic delivery of chemical substances 
without necessitating liquid flow. Biosensors detected neurotransmitters in 
physiologically relevant ranges of 5–80 µM, showing linear response above 
20 µm with approx. 0.1 nA/µM slope. When exceeding defined threshold 
concentrations, biosensor output signals, connected via custom 
hardware/software, activated local or distant neurotransmitter delivery 
from the organic electronic ion pump. Changes of 20 µM glutamate or 
acetylcholine triggered diffusive delivery of acetylcholine, which 
activated cells via receptor-mediated signalling. This was observed in 
real-time by single-cell ratiometric Ca2+ imaging. The results demonstrate 
the potential of the organic electronic biomimetic neuron in therapies 
involving long-range neuronal signaling by mimicking the function of 
projection neurons. Alternatively, conversion of glutamate-induced 
descending neuromuscular signals into acetylcholine-mediated muscular 
activation signals may be obtained, applicable for bridging injured sites 
and active prosthetics.

- pt


 

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Discrete theories of space.

[John Clark]

On Saturday, January 19, 2019 at 5:22:25 PM UTC-6, Philip Thrift wrote:

> *T*
>
>
> *his by Carlo Rovelli:> https://arxiv.org/abs/1802.02382
> > concludes:> "Notice that nowhere in the
> basic equations of the theory a time coordinate t or a space coordinate x
> show up**"*.


Experiments involve space and time, if those equations involve neither I
don't see how you could ever test them to see if they're correct;  and if
you can't do that then it's not science, it's just philosophy. And
philosophers have been proven wrong far more often than proven right.

 John K Clark

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Re: Planck Length

[Bruno Marchal]

> On 19 Jan 2019, at 11:36, Philip Thrift  wrote:
> 
> 
> 
> On Saturday, January 19, 2019 at 2:36:23 AM UTC-6, Bruno Marchal wrote:
> 
>> On 18 Jan 2019, at 15:44, Philip Thrift > 
>> wrote:
>> 
>> 
>> 
>> On Friday, January 18, 2019 at 7:36:34 AM UTC-6, Bruno Marchal wrote:
>> 
>>> On 17 Jan 2019, at 21:02, Philip Thrift > wrote:
>>> 
>>> 
>>> 
>>> On Thursday, January 17, 2019 at 12:45:31 PM UTC-6, Brent wrote:
>>> 
>>> 
>>> On 1/17/2019 12:22 AM, agrays...@gmail.com <> wrote:
 Later I'll post some questions I have about your derivation of the Planck 
 length, but for now here's a philosophical question; Is there any 
 difference between the claim that space is discrete, from the claim or 
 conjecture that we cannot in principle measure a length shorter than the 
 Planck length? 
 TIA, AG
>>> 
>>> The theory that predicts there is a shortest measured interval assumes a 
>>> continuum.  There's no logical contradiction is this. But physicists tend 
>>> to have a positivist attitude and think that a theory that assumes things, 
>>> like arbitrarily short intervals, might be better expressed and simpler in 
>>> some way that avoids those assumptions.  This attitude does not assume the 
>>> mathematics itself is the reality, but only a description of reality; so 
>>> there can be different descriptions of the same reality.
>>> 
>>> Brent
>>> 
>>> 
>>> 
>>> A theory that does this assumes a continuous mathematics.
>>> But that doesn't mean every theory has to.
>>> 
>>> As Max Tegmark's little lecture to physicists says:
>>> 
>>> Our challenge as physicists is to discover ... infinity-free equations.
>>> 
>>> http://blogs.discovermagazine.com/crux/2015/02/20/infinity-ruining-physics/#.XEDdLs9KiCQ
>>>  
>>> 
>>> 
>>> Unless he is wrong in his premise, of course!
>> 
>> 
>> That assumes non-mechanism, and thus bigger infinities. Tegmark is right: we 
>> cannot assume infinity at the ontological level (just the finite numbers 0, 
>> s(0), s(s(0)), …). But the physical reality is phenomenological, and 
>> requires infinite domain of indetermination, making some “observable” having 
>> an infinite range. The best candidate could be graham-Preskill frequency 
>> operator (that they use more or less rigorously to derive the Born rule from 
>> some “many-worlds” interpretation of QM.
>> 
>> Bruno
>> 
>> 
>> 
>> 
>> 
>> I think it is possible some of this can be approached with what is referred 
>> to as higher-type computing, where 
>> 
>> higher-type computing is about
>> 
>> -  the characterization of the sets that can be exhaustively searched [1] by 
>> an algorithm, in the sense of Turing, in finite time, as those that are 
>> topologically compact
>> 
>> - infinite sets that can be completely inspected in finite time in an 
>> algorithmic way, which perhaps defies intuition
>> 
>> [1] Exhaustible sets in higher-type computation
>>  https://arxiv.org/abs/0808.0441 
>> [2] A Haskell monad for infinite search in finite time
>>  
>> http://math.andrej.com/2008/11/21/a-haskell-monad-for-infinite-search-in-finite-time/
>>  
>> 
>> 
>> from Martin Escardo's page
>>  http://www.cs.bham.ac.uk/~mhe/ 
>> 
>>  - pt
> 
> 
> That is the constructive move. With mechanism, this is given by S4Grz1, 
> and/or typing the combinators. It corresponds to the first person. Tegmark 
> seems oscillate between third and first person views, but when taking 
> mechanism seriously *in the cognitive science* (and not in physics), we have 
> to take both points of view, and derive their relations from self-reference. 
> As I said, the 1p/3p relation is more subtle than the bird/frog change of 
> scale.
> 
> You might try to explain Haskell monad for infinite search in finite time. 
> Mechanism explains this from the first person point of view, but is not seen 
> as being something algorithmic.
> 
> Bruno
> 
> 
> 
> The key to the higher-type computing approach
> 
> from Infinite sets that admit fast exhaustive search
>  http://www.cs.bham.ac.uk/~mhe/papers/exhaustive.pdf
> 
> 
> is to relate a certain kind of computing to topology
> 
>exhaustible sets are to compact sets as 
>computable functions are to continuous maps
> 
> There is one example in the above paper [code below]  (I haven't run any of 
> his code).
> 
> 
> It should be really be called something like  topological computing: 
> 
> Programs that are like continuous maps have the property that even though 
> they apparently deal with infinite objects, because these objects are (in a 
> computationally-defined way) topological compact, their computing time is 
> finite (and maybe even efficient).


As I said, a sort of topological intuition arise from the modes []p & p (p 
sigma_1)

Re: Planck Length

[Bruno Marchal]

> On 19 Jan 2019, at 01:42, Lawrence Crowell  
> wrote:
> 
> On Thursday, January 17, 2019 at 6:31:06 AM UTC-6, Bruno Marchal wrote:
> 
>> On 17 Jan 2019, at 09:22, agrays...@gmail.com  wrote:
>> 
>> 
>> 
>> On Monday, January 7, 2019 at 9:25:16 PM UTC, John Clark wrote:
>> On Mon, Jan 7, 2019 at 8:03 AM > wrote:
>> 
>> > How does one calculate Planck length using the fundamental constants G, h, 
>> > and c, and having calculated it, how does one show that measuring a length 
>> > that small with photons of the same approximate wave length, would result 
>> > in a black hole? TIA, AG
>>  
>> In any wave the speed of the wave is wavelength times frequency and 
>> according to Planck E= h*frequency  so E= C*h/wavelength.  Thus the smaller 
>> the wavelength the greater the energy. According to Einstein energy is just 
>> another form of mass (E = MC^2) so at some point the wavelength is so small 
>> and the light photon is so energetic (aka massive) that the escape velocity 
>> is greater than the speed of light and the object becomes a Black Hole.
>> 
>> Or you can look at it another way, we know from Heisenberg that to determine 
>> the position of a particle more precisely with light you have to use a 
>> smaller wavelength, and there is something called the  "Compton wavelength" 
>> (Lc) ; to pin down the position of a particle of mass m to within one 
>> Compton wavelength would require light of enough energy to create another 
>> particle of that mass. The formula for the Compton Wavelength is Lc= 
>> h/(2PI*M*c).
>> 
>> Schwarzschild told us that the radius of a Black Hole (Rs), that is to say 
>> where the escape velocity is the speed of light  is:  Rs= GM/c^2. At some 
>> mass Lc will equal Rs and that mass is the Planck mass, and that Black Hole 
>> will have the radius of the Planck Length, 1.6*10^-35 meters.
>> 
>> Then if you do a little algebra:
>> GM/c^2 = h/(2PI*M*c)
>> GM= hc/2PI*M
>> GM^2 = hc/2*PI
>> M^2 = hc/2*PI*G
>> M = (hc/2*PI*G)^1/2and that is the formula for the Planck Mass , it's 
>> .02 milligrams.
>> 
>> And the Planck Length turns out to be (G*h/2*PI*c^3)^1/2 and the Planck time 
>> is the time it takes light to travel the Planck length. 
>> 
>> The Planck Temperature Tp is sort of the counterpoint to Absolute Zero, Tp 
>> is as hot as things can get because the black-body radiation given off by 
>> things when they are at temperature Tp have a wavelength equal to the Planck 
>> Length, the distance light can move in the Planck Time of 10^-44 seconds. 
>> The formula for the Planck temperature is Tp = Mp*c^2/k where Mp is the 
>> Planck Mass and K is Boltzmann's constant and it works out to be 1.4*10^32 
>> degrees Kelvin.  Beyond that point both Quantum Mechanics and General 
>> Relativity break down and nobody understands what if anything is going on.
>> 
>> The surface temperature of the sun is at 5.7 *10^3  degrees Kelvin so if it 
>> were 2.46*10^28 times hotter it would be at the Planck Temperature, and 
>> because radiant energy is proportional to T^4 the sun would be 3.67*10^113 
>> times brighter. At that temperature to equal the sun's brightness the 
>> surface area would have to be reduced by a factor of 3.67*10^113, the 
>> surface area of a sphere is proportional to the radius squared, so you'd 
>> have to reduce the sun's radius by (3.67*10^113)^1/2, and that is  
>> 6.05*10^56. The sun's radius is 6.95*10^8   meters and  6.95*10^8/ 
>> 6.05*10^56  is 1.15^10^-48 meters. 
>> 
>> That means a sphere at the Planck Temperature with a radius 10 thousand 
>> billion times SMALLER than the Planck Length would be as bright as the sun, 
>> but as far as we know nothing can be that small. If the radius was 10^13 
>> times longer it would be as small as things can get and the object would be 
>> (10^13)^2 = 10^26 times as bright as the sun. I'm just speculating but 
>> perhaps that's the luminosity of the Big Bang; I say that because that's how 
>> bright things would be if the smallest thing we think can exist was as hot 
>> as we think things can get. 
>> 
>> John K Clark
>> 
>> Later I'll post some questions I have about your derivation of the Planck 
>> length, but for now here's a philosophical question; Is there any difference 
>> between the claim that space is discrete, from the claim or conjecture that 
>> we cannot in principle measure a length shorter than the Planck length? 
>> TIA, AG 
> 
> That is a very good question. I have no answer. I don’t think physicists have 
> an answer either, and I do think that this requires the solution of the 
> “quantum gravity” or the “quantum space-time” problem. 
> With loop-gravity theory, I would say that the continuum is eventually 
> replaced by something discrete, but not so with string theory; for example. 
> With Mechanism, there are argument that something must stay “continuous”, but 
> it might be only the distribution of probability (the real-complex 
> amplitude). 
> 
> Bruno
> 
> The Planck length is just the 

Re: Discrete theories of space

[Lawrence Crowell]

On Saturday, January 19, 2019 at 5:42:12 AM UTC-6, agrays...@gmail.com 
wrote:
>
> Since it seems conceptually impossible to model a theory with DISJOINT 
> discrete spatial units, thus requiring the units to be juxtaposed, do such 
> theories acknowledge difficulty of motion between the units, which might or 
> might not have boundaries? TIA, AG
>

I am not sure how to impress people with how bad this thinking is. These 
slice and diced chunks of spacetime, whether voxels, plaquettes and so 
forth have violations of Lorentz symmetry of spacetime. This means that 
curiously the symmetry of gravitation would be violated at higher energy, 
and in fact where it is quantized. These ideas have further been falsified 
by the lack of dispersion from distant sources. These ideas are bad 
interpretations of the Planck length. The Planck length is just the 
smallest length beyond which you can isolate a quantum bit. Remember, it is 
the length at which the Compton wavelength of a black hole equals its 
Schwarzschild radius. It is a bit similar to the Nyquist frequency in 
engineering. In order to measure the frequency of a rotating system you 
must take pictures that are at least double that frequency. Similarly to 
measure the frequency of an EM wave you need to have a wave with Fourier 
modes that are 2 or more times the frequency you want to measure. The black 
hole is in a sense a fundamental cut-off in the time scale, or in a 
reciprocal manner the energy, one can sample space to find qubits. 

The levels of confusion over this are enormous. It does not tell us that 
spacetime is somehow sliced and diced into briquets or pieces. It does not 
tell us that quantum energy of some fields can't be far larger than the 
Planck energy, or equivalently the wavelength much smaller. This would be 
analogous to a resonance state, and there is no reason there can't be such 
a thing in quantum gravity. The Planck scale would suggest this sort of 
state may decay into a sub-Planckian energy.  Further, it is plausible that 
quantum gravity beyond what appears as a linearized weak field 
approximation similar to the QED of photon bunched pairs may only exist at 
most an order of magnitude larger than the Planck scale anyway. A 
holographic screen is then a sort of beam splitter at the quantum-classical 
divide.

LC

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Re: The semantic view of theories and higher-order languages

[Bruno Marchal]

> On 19 Jan 2019, at 00:14, John Clark  wrote:
> 
> On Fri, Jan 18, 2019 at 8:30 AM Bruno Marchal  > wrote:
> 
> >Nwe cannot assume, neither a physical universe, nor analysis or set theory. 
> >Since recently, I have realised that we cannot even assume the induction 
> >axioms,
> 
> Induction says that things are usually pretty much the same from one moment 
> of time to the next and from one point in space to a nearby one,


That is the case for inductive inference, but here I was alluding to the 
induction axioms, which are used only in deduction.

The induction axioms on the numbers is 

P(0) & [For all n (P(n) -> P(s(n)))] ->. For all n P(n).

Or, for the combinators, it is

P(K) & P(S) & [For all x y ((P(x) & P(y)) -> P(xy)) -> For all x P(x)

I do think that inductive inference has deep relation with mathematical 
induction, though. But that is beyond the cope of this post.



> if Everett is right (and my hunch is he is) for some universes that would be 
> true, but such  a chaotic universe would not have structures capable of 
> producing thought or consciousness. Therefore  it is not only safe for us to 
> assume induction we DO assume it and we could not survive in the physical 
> world longer than about 45 seconds without it. At this very second although I 
> have no detailed knowledge of the wiring involved and have not seen the 
> blueprints I am assuming that when I hit the key marked "I" on my keyboard a 
> "I" symbol will appear on my screen; I assume it will happen this time 
> because that's what usually happened in the past, the only time it didn't was 
> when my keyboard was defective a few years ago but that was quickly replaced. 

But when used in physics, this type of inductive inference assume not only a 
reality, but a “brain-mind” identity, which is not consistent with the 
mechanist hypothesis.

Bruno




> 
>  John K Clark  
> 
> 
> 
> 
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Re: Solomonoff induction and mechanism

[Bruno Marchal]

> On 16 Jan 2019, at 05:05, Russell Standish  wrote:
> 
> On Fri, Jan 11, 2019 at 06:14:14PM -0800, 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.
> 
> It doesn't work like that. Let's say that the mᵢ is the measure of
> our universe by program i, and Kᵢ the Kolmogorov complexity of that
> program, with respect to some fixed reference universal machine U.
> 
> Then for any universal dovetailer u, m_u will be >= ∑ⱼ 2^{-Kⱼ} mⱼ, so
> there will be at most only be a short constant difference Kᵤ in
> complexity between the universe implemented on universal dovetailer
> and the one implemented on the non-universal dovetailer. Once you sum
> over all programs, m=∑ⱼ2^{-Kⱼ}mⱼ, converges to a value that is basic 2
> to the power of the complexity of our universe. The sum will be
> dominated by contributions from universal dovetailers, as these are
> such short programs.
> 
> 
>> 
>> 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.
>> 
> 
> One could say this about any property, such as the density of black
> holes present, or flatness of the universe. It is the stuff of
> anthropic reasoning. However, computing the measure of even those
> formulae expressed above in known to be highly intractible, so what
> tends to happen is a bunch of heuristics are assumed about the
> measure, which may well make the whole argument devoid of meaning…



The measure is on the first person experiences, which needs the “theaetetus' 
solution" of the “knower” problem. It works, because incompleteness refutes 
Socrate’s refutation, and it also, provides, thanks to incompleteness again, 
the distinction between private non communicable knowledge, and sharable 
beliefs, or even the locally sharable first person *plural* relative measure on 
the physical predictions. Physics still needs an identity thesis to make its 
prediction, and that one is only locally correct, but globally, and 
fundamentally, inoperative.

Bruno



> 
> 
> -- 
> 
> 
> Dr Russell StandishPhone 0425 253119 (mobile)
> Principal, High Performance Coders
> Visiting Senior Research Fellowhpco...@hpcoders.com.au
> Economics, Kingston University http://www.hpcoders.com.au
> 
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Re: UDA and the origin of physics

[Bruno Marchal]

> On 15 Jan 2019, at 12:56, Philip Thrift  wrote:
> 
> 
> 
> On Tuesday, January 15, 2019 at 5:33:01 AM UTC-6, Bruno Marchal wrote:
> 
> > On 14 Jan 2019, at 20:27, Brent Meeker > 
> > wrote: 
> > 
> > 
> > 
> > On 1/14/2019 3:22 AM, Bruno Marchal wrote: 
> >> The physics comes from the first person statistical interference between 
> >> those dreams. 
> > 
> > Where can this "person" be to make a statisical inference, if there are 
> > only the dreams? 
> > 
> 
> That person makes the inference in the dreams, and test them in the mean 
> (most normal, in the Gaussian sense) consistent extensions where it 
> consciousness differentiate. 
> 
> Those dream are not “nocturnal” type of dream. A dream here is just a 
> computation supporting a Löbian machine, which itself supports a person ([]p 
> &p). The measure one is given either by []p & p (p sigma_1), or just []p & 
> <>t. “[]p” alone cannot work, because G adds “cul-de-sac world” at any 
> transition, and we have to get rid of them, to get the default hypotheses 
> used in probability or credibility theory. 
> 
> We do reverse engineering somehow. We extract the geometry of the universe 
> (the accessibility relations) from the modal logic of the 
> observable/predictable, which is derived from the “material variants” of G 
> (mainly Z). 
> 
> With mechanism, there are no other way, unless adding a magical selection 
> principle, but that would make impossible to trust any digitalist doctors. 
> Would you say yes to a doctor who says that the transplant needs some prayer? 
> 
> Bruno 
> 
> 
> 
> But what exactly counts as a digital implant?
> 
>  Likely, neurosurgeons in the future will be replacing neurons and groups of 
> neurons in human brains with synthetic neurons made of some sort of 
> materials, perhaps including silicon, but also biopolymers …


An implant can be said digital if it is emulable at the relevant substitution 
level (that we cannot know for sure, that is why it is a sort of bet).

If the primitive matter plays a role, it has to be non Turing emulable at all, 
but there are no evidences for this, and some contrary evidences do exist.

Bruno



> 
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Re: Coherent states of a superposition

['scerir' via Everything List]

> Il 20 gennaio 2019 alle 13.25 agrayson2...@gmail.com ha scritto:
> 
> 
> 
> On Sunday, January 20, 2019 at 12:10:25 PM UTC, scerir wrote:
> 
> > > 
> > 
> > > > > Il 20 gennaio 2019 alle 12.56 agrays...@gmail.com ha 
> > scritto:
> > > 
> > > 
> > > 
> > > On Sunday, January 20, 2019 at 10:46:01 AM UTC, scerir wrote:
> > > 
> > > > > > > 
> > > > 
> > > > [BRUNO writes] It has a non null amplitude of 
> > > > probability of being here and there at the same time, like having a non 
> > > > null amplitude of probability of going through each slit in the two 
> > > > slits experience. If not, you can’t explain the inference patterns, 
> > > > especially in the photon self-interference.
> > > > 
> > > > 
> > > > Interesting to point out that, in the two-slit, it is 
> > > > possible to have interference even when there is just one slit open 
> > > > (and the other slit shut, and viceversa, with some appropriate 
> > > > frequence). In this case it seems that the two amplitudes cannot 
> > > > interfere.
> > > > 
> > > > - Leonard Mandel : "On the Possibility of Observing 
> > > > Interference Effects with Light Beams Divided by a Shutter", 
> > > > J.Opt.Soc.Amer.,
> > > > 49, (1959), 931.
> > > > - R.M. Sillitto, Catherine Wykes: "An Interference 
> > > > Experiment With Light Beams Modulated In Anti-Phase By An Electro-Optic 
> > > > Shutter",
> > > > Physics Letters, 39-A-4, (1972), 333-334.
> > > > 
> > > > > > > 
> > > Isn't this called diffraction? AG
> > > 
> > > > > 
> > No, they show it is interference
> > 
> > > 
> ??? CMIIAW, but I'm pretty sure that single slit interference is called 
> DIFFRACTION. There is interference for a single slit. Apply Huygen's 
> principle where each point in the slit acts as source of waves which mutually 
> interference. AG
> 

Interference is interference. Diffraction is diffraction.

After useful considerations by Leonard Mandel [J. Opt. Soc. Amer., 49, (1959), 
931] at last R.M. Sillitto and Catherine Wykes [Physics Letters, 39-A-4, 
(1972), 333] performed the experiment suggested by Janossy and Nagy (1956) and 
found a beautiful INTERFERENCE when just one photon was present in their 
interferometer, at a time, and when their electro-optic shutter (closing one or 
the other slit, alternatively) was switched several times during the 
time-travel of each photon.

In terms of photons (that is to say: particles) the condition for INTERFERENCE 
is that the two in principle *possible* paths lead to the same cell of phase 
space, so that the path of each photon is intrinsically indeterminate (the 
usual 'welcher weg', or 'which path', issue).

Of course the shutter must be switched in a time which is less than the 
uncertainty in the time arrival of the photon.

In other words. Here the INTERFERENCE seems to be due to the 
indistinguishability of the two possible paths (only one of these paths is 
actual, because there is that shutter). It is very difficult to see here an 
interference between two amplitudes.

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Re: Coherent states of a superposition

[agrayson2000]

On Sunday, January 20, 2019 at 12:10:25 PM UTC, scerir wrote:
>
>
> Il 20 gennaio 2019 alle 12.56 agrays...@gmail.com  ha 
> scritto: 
>
>
>
> On Sunday, January 20, 2019 at 10:46:01 AM UTC, scerir wrote:
>
>
> [BRUNO writes] It has a non null amplitude of probability of being here 
> and there at the same time, like having a non null amplitude of probability 
> of going through each slit in the two slits experience. If not, you can’t 
> explain the inference patterns, especially in the photon self-interference.
>
>
> Interesting to point out that, in the two-slit, it is possible to have 
> interference even when there is just one slit open (and the other slit 
> shut, and viceversa, with some appropriate frequence). In this case it 
> seems that the two amplitudes cannot interfere. 
>
> - Leonard Mandel : "On the Possibility of Observing Interference Effects 
> with Light Beams Divided by a Shutter", J.Opt.Soc.Amer., 
> 49, (1959), 931. 
> - R.M. Sillitto, Catherine Wykes: "An Interference Experiment With Light 
> Beams Modulated In Anti-Phase By An Electro-Optic Shutter", 
> Physics Letters, 39-A-4, (1972), 333-334.
>
>
> *Isn't this called diffraction? AG *
>
> No, they show it is interference
>


*??? CMIIAW, but I'm pretty sure that single slit interference is called 
DIFFRACTION. There is interference for a single slit. Apply Huygen's 
principle where each point in the slit acts as source of waves which 
mutually interference. AG *

>  
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Re: Coherent states of a superposition

['scerir' via Everything List]

> Il 20 gennaio 2019 alle 12.56 agrayson2...@gmail.com ha scritto:
> 
> 
> 
> On Sunday, January 20, 2019 at 10:46:01 AM UTC, scerir wrote:
> 
> > > 
> > 
> > [BRUNO writes] It has a non null amplitude of probability of being 
> > here and there at the same time, like having a non null amplitude of 
> > probability of going through each slit in the two slits experience. If not, 
> > you can’t explain the inference patterns, especially in the photon 
> > self-interference.
> > 
> > 
> > Interesting to point out that, in the two-slit, it is possible to 
> > have interference even when there is just one slit open (and the other slit 
> > shut, and viceversa, with some appropriate frequence). In this case it 
> > seems that the two amplitudes cannot interfere.
> > 
> > - Leonard Mandel : "On the Possibility of Observing Interference 
> > Effects with Light Beams Divided by a Shutter", J.Opt.Soc.Amer.,
> > 49, (1959), 931.
> > - R.M. Sillitto, Catherine Wykes: "An Interference Experiment With 
> > Light Beams Modulated In Anti-Phase By An Electro-Optic Shutter",
> > Physics Letters, 39-A-4, (1972), 333-334.
> > 
> > > 
> Isn't this called diffraction? AG
> 

No, they show it is interference

> 
>  
> 
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Re: Coherent states of a superposition

[agrayson2000]

On Sunday, January 20, 2019 at 11:54:43 AM UTC, agrays...@gmail.com wrote:
>
>
>
> On Sunday, January 20, 2019 at 9:56:17 AM UTC, Bruno Marchal wrote:
>>
>>
>> On 18 Jan 2019, at 18:50, agrays...@gmail.com wrote:
>>
>>
>>
>> On Friday, January 18, 2019 at 12:09:58 PM UTC, Bruno Marchal wrote:
>>>
>>>
>>> On 17 Jan 2019, at 14:48, agrays...@gmail.com wrote:
>>>
>>>
>>>
>>> On Thursday, January 17, 2019 at 12:36:07 PM UTC, Bruno Marchal wrote:


 On 17 Jan 2019, at 09:33, agrays...@gmail.com wrote:



 On Thursday, January 17, 2019 at 3:58:48 AM UTC, Brent wrote:
>
>
>
> On 1/16/2019 7:25 PM, agrays...@gmail.com wrote:
>
>
>
> On Monday, January 14, 2019 at 6:12:43 AM UTC, Brent wrote: 
>>
>>
>>
>> On 1/13/2019 9:51 PM, agrays...@gmail.com wrote:
>>
>> This means, to me, that the arbitrary phase angles have absolutely no 
>> effect on the resultant interference pattern which is observed. But 
>> isn't 
>> this what the phase angles are supposed to effect? AG
>>
>>
>> The screen pattern is determined by *relative phase angles for the 
>> different paths that reach the same point on the screen*.  The 
>> relative angles only depend on different path lengths, so the overall 
>> phase 
>> angle is irrelevant.
>>
>> Brent
>>
>
>
> *Sure, except there areTWO forms of phase interference in Wave 
> Mechanics; the one you refer to above, and another discussed in the 
> Stackexchange links I previously posted. In the latter case, the wf is 
> expressed as a superposition, say of two states, where we consider two 
> cases; a multiplicative complex phase shift is included prior to the sum, 
> and different complex phase shifts multiplying each component, all of the 
> form e^i (theta). Easy to show that interference exists in the latter 
> case, 
> but not the former. Now suppose we take the inner product of the wf with 
> the ith eigenstate of the superposition, in order to calculate the 
> probability of measuring the eigenvalue of the ith eigenstate, applying 
> one 
> of the postulates of QM, keeping in mind that each eigenstate is 
> multiplied 
> by a DIFFERENT complex phase shift.  If we further assume the eigenstates 
> are mutually orthogonal, the probability of measuring each eigenvalue 
> does 
> NOT depend on the different phase shifts. What happened to the 
> interference 
> demonstrated by the Stackexchange links? TIA, AG *
>
> Your measurement projected it out. It's like measuring which slit the 
> photon goes through...it eliminates the interference.
>
> Brent
>

 *That's what I suspected; that going to an orthogonal basis, I departed 
 from the examples in Stackexchange where an arbitrary superposition is 
 used 
 in the analysis of interference. Nevertheless, isn't it possible to 
 transform from an arbitrary superposition to one using an orthogonal 
 basis? 
 And aren't all bases equivalent from a linear algebra pov? If all bases 
 are 
 equivalent, why would transforming to an orthogonal basis lose 
 interference, whereas a general superposition does not? TIA, AG*


 I don’t understand this. All the bases we have used all the time are 
 supposed to be orthonormal bases. We suppose that the scalar product (e_i 
 e_j) = delta_i_j, when presenting the Born rule, and the quantum formalism.

 Bruno

>>>
>>> *Generally, bases in a vector space are NOT orthonormal. *
>>>
>>>
>>> Right. But we can always build an orthonormal base with a decent scalar 
>>> product, like in Hilbert space, 
>>>
>>>
>>>
>>> *For example, in the vector space of vectors in the plane, any pair of 
>>> non-parallel vectors form a basis. Same for any general superposition of 
>>> states in QM. HOWEVER, eigenfunctions with distinct eigenvalues ARE 
>>> orthogonal.*
>>>
>>>
>>> Absolutely. And when choosing a non degenerate 
>>> observable/measuring-device, we work in the base of its eigenvectors. A 
>>> superposition is better seen as a sum of some eigenvectors of some 
>>> observable. That is the crazy thing in QM. The same particle can be 
>>> superposed in the state of being here and there. Two different positions of 
>>> one particle can be superposed.
>>>
>>
>> *This is a common misinterpretation. Just because a wf can be expressed 
>> in different ways (as a vector in the plane can be expressed in uncountably 
>> many different bases), doesn't mean a particle can exist in different 
>> positions in space at the same time. AG*
>>
>>
>> It has a non null amplitude of probability of being here and there at the 
>> same time, like having a non null amplitude of probability of going through 
>> each slit in the two slits experience.
>>
>> If not, you can’t explain the inference patterns, especially in the 
>> phot

Re: Coherent states of a superposition

[agrayson2000]

On Sunday, January 20, 2019 at 10:46:01 AM UTC, scerir wrote:
>
>
> [BRUNO writes] It has a non null amplitude of probability of being here 
> and there at the same time, like having a non null amplitude of probability 
> of going through each slit in the two slits experience. If not, you can’t 
> explain the inference patterns, especially in the photon self-interference.
>
>
> Interesting to point out that, in the two-slit, it is possible to have 
> interference even when there is just one slit open (and the other slit 
> shut, and viceversa, with some appropriate frequence). In this case it 
> seems that the two amplitudes cannot interfere. 
>
> - Leonard Mandel : "On the Possibility of Observing Interference Effects 
> with Light Beams Divided by a Shutter", J.Opt.Soc.Amer., 
> 49, (1959), 931.
> - R.M. Sillitto, Catherine Wykes: "An Interference Experiment With Light 
> Beams Modulated In Anti-Phase By An Electro-Optic Shutter", 
> Physics Letters, 39-A-4, (1972), 333-334.
>


*Isn't this called diffraction? AG *

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Re: Coherent states of a superposition

[agrayson2000]

On Sunday, January 20, 2019 at 9:56:17 AM UTC, Bruno Marchal wrote:
>
>
> On 18 Jan 2019, at 18:50, agrays...@gmail.com  wrote:
>
>
>
> On Friday, January 18, 2019 at 12:09:58 PM UTC, Bruno Marchal wrote:
>>
>>
>> On 17 Jan 2019, at 14:48, agrays...@gmail.com wrote:
>>
>>
>>
>> On Thursday, January 17, 2019 at 12:36:07 PM UTC, Bruno Marchal wrote:
>>>
>>>
>>> On 17 Jan 2019, at 09:33, agrays...@gmail.com wrote:
>>>
>>>
>>>
>>> On Thursday, January 17, 2019 at 3:58:48 AM UTC, Brent wrote:



 On 1/16/2019 7:25 PM, agrays...@gmail.com wrote:



 On Monday, January 14, 2019 at 6:12:43 AM UTC, Brent wrote: 
>
>
>
> On 1/13/2019 9:51 PM, agrays...@gmail.com wrote:
>
> This means, to me, that the arbitrary phase angles have absolutely no 
> effect on the resultant interference pattern which is observed. But isn't 
> this what the phase angles are supposed to effect? AG
>
>
> The screen pattern is determined by *relative phase angles for the 
> different paths that reach the same point on the screen*.  The 
> relative angles only depend on different path lengths, so the overall 
> phase 
> angle is irrelevant.
>
> Brent
>


 *Sure, except there areTWO forms of phase interference in Wave 
 Mechanics; the one you refer to above, and another discussed in the 
 Stackexchange links I previously posted. In the latter case, the wf is 
 expressed as a superposition, say of two states, where we consider two 
 cases; a multiplicative complex phase shift is included prior to the sum, 
 and different complex phase shifts multiplying each component, all of the 
 form e^i (theta). Easy to show that interference exists in the latter 
 case, 
 but not the former. Now suppose we take the inner product of the wf with 
 the ith eigenstate of the superposition, in order to calculate the 
 probability of measuring the eigenvalue of the ith eigenstate, applying 
 one 
 of the postulates of QM, keeping in mind that each eigenstate is 
 multiplied 
 by a DIFFERENT complex phase shift.  If we further assume the eigenstates 
 are mutually orthogonal, the probability of measuring each eigenvalue does 
 NOT depend on the different phase shifts. What happened to the 
 interference 
 demonstrated by the Stackexchange links? TIA, AG *

 Your measurement projected it out. It's like measuring which slit the 
 photon goes through...it eliminates the interference.

 Brent

>>>
>>> *That's what I suspected; that going to an orthogonal basis, I departed 
>>> from the examples in Stackexchange where an arbitrary superposition is used 
>>> in the analysis of interference. Nevertheless, isn't it possible to 
>>> transform from an arbitrary superposition to one using an orthogonal basis? 
>>> And aren't all bases equivalent from a linear algebra pov? If all bases are 
>>> equivalent, why would transforming to an orthogonal basis lose 
>>> interference, whereas a general superposition does not? TIA, AG*
>>>
>>>
>>> I don’t understand this. All the bases we have used all the time are 
>>> supposed to be orthonormal bases. We suppose that the scalar product (e_i 
>>> e_j) = delta_i_j, when presenting the Born rule, and the quantum formalism.
>>>
>>> Bruno
>>>
>>
>> *Generally, bases in a vector space are NOT orthonormal. *
>>
>>
>> Right. But we can always build an orthonormal base with a decent scalar 
>> product, like in Hilbert space, 
>>
>>
>>
>> *For example, in the vector space of vectors in the plane, any pair of 
>> non-parallel vectors form a basis. Same for any general superposition of 
>> states in QM. HOWEVER, eigenfunctions with distinct eigenvalues ARE 
>> orthogonal.*
>>
>>
>> Absolutely. And when choosing a non degenerate 
>> observable/measuring-device, we work in the base of its eigenvectors. A 
>> superposition is better seen as a sum of some eigenvectors of some 
>> observable. That is the crazy thing in QM. The same particle can be 
>> superposed in the state of being here and there. Two different positions of 
>> one particle can be superposed.
>>
>
> *This is a common misinterpretation. Just because a wf can be expressed in 
> different ways (as a vector in the plane can be expressed in uncountably 
> many different bases), doesn't mean a particle can exist in different 
> positions in space at the same time. AG*
>
>
> It has a non null amplitude of probability of being here and there at the 
> same time, like having a non null amplitude of probability of going through 
> each slit in the two slits experience.
>
> If not, you can’t explain the inference patterns, especially in the photon 
> self-interference.
>
>
>
>
>
> Using a non orthonormal base makes only things more complex. 
>>
> * I posted a link to this proof a few months ago. IIRC, it was on its 
>> specifically named thread. AG*
>>
>>
>> But all this makes my poi

Re: Coherent states of a superposition

['scerir' via Everything List]

[BRUNO writes] It has a non null amplitude of probability of being here and 
there at the same time, like having a non null amplitude of probability of 
going through each slit in the two slits experience. If not, you can’t explain 
the inference patterns, especially in the photon self-interference.


Interesting to point out that, in the two-slit, it is possible to have 
interference even when there is just one slit open (and the other slit shut, 
and viceversa, with some appropriate frequence). In this case it seems that the 
two amplitudes cannot interfere.

- Leonard Mandel : "On the Possibility of Observing Interference Effects with 
Light Beams Divided by a Shutter", J.Opt.Soc.Amer.,
49, (1959), 931.
- R.M. Sillitto, Catherine Wykes: "An Interference Experiment With Light Beams 
Modulated In Anti-Phase By An Electro-Optic Shutter",
Physics Letters, 39-A-4, (1972), 333-334.

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Re: Coherent states of a superposition

[Bruno Marchal]

> On 18 Jan 2019, at 18:50, agrayson2...@gmail.com wrote:
> 
> 
> 
> On Friday, January 18, 2019 at 12:09:58 PM UTC, Bruno Marchal wrote:
> 
>> On 17 Jan 2019, at 14:48, agrays...@gmail.com  wrote:
>> 
>> 
>> 
>> On Thursday, January 17, 2019 at 12:36:07 PM UTC, Bruno Marchal wrote:
>> 
>>> On 17 Jan 2019, at 09:33, agrays...@gmail.com <> wrote:
>>> 
>>> 
>>> 
>>> On Thursday, January 17, 2019 at 3:58:48 AM UTC, Brent wrote:
>>> 
>>> 
>>> On 1/16/2019 7:25 PM, agrays...@gmail.com <> wrote:
 
 
 On Monday, January 14, 2019 at 6:12:43 AM UTC, Brent wrote:
 
 
 On 1/13/2019 9:51 PM, agrays...@gmail.com <> wrote:
> This means, to me, that the arbitrary phase angles have absolutely no 
> effect on the resultant interference pattern which is observed. But isn't 
> this what the phase angles are supposed to effect? AG
 
 The screen pattern is determined by relative phase angles for the 
 different paths that reach the same point on the screen.  The relative 
 angles only depend on different path lengths, so the overall phase angle 
 is irrelevant.
 
 Brent
 
 Sure, except there areTWO forms of phase interference in Wave Mechanics; 
 the one you refer to above, and another discussed in the Stackexchange 
 links I previously posted. In the latter case, the wf is expressed as a 
 superposition, say of two states, where we consider two cases; a 
 multiplicative complex phase shift is included prior to the sum, and 
 different complex phase shifts multiplying each component, all of the form 
 e^i (theta). Easy to show that interference exists in the latter case, but 
 not the former. Now suppose we take the inner product of the wf with the 
 ith eigenstate of the superposition, in order to calculate the probability 
 of measuring the eigenvalue of the ith eigenstate, applying one of the 
 postulates of QM, keeping in mind that each eigenstate is multiplied by a 
 DIFFERENT complex phase shift.  If we further assume the eigenstates are 
 mutually orthogonal, the probability of measuring each eigenvalue does NOT 
 depend on the different phase shifts. What happened to the interference 
 demonstrated by the Stackexchange links? TIA, AG 
 
>>> Your measurement projected it out. It's like measuring which slit the 
>>> photon goes through...it eliminates the interference.
>>> 
>>> Brent
>>> 
>>> That's what I suspected; that going to an orthogonal basis, I departed from 
>>> the examples in Stackexchange where an arbitrary superposition is used in 
>>> the analysis of interference. Nevertheless, isn't it possible to transform 
>>> from an arbitrary superposition to one using an orthogonal basis? And 
>>> aren't all bases equivalent from a linear algebra pov? If all bases are 
>>> equivalent, why would transforming to an orthogonal basis lose 
>>> interference, whereas a general superposition does not? TIA, AG
>> 
>> I don’t understand this. All the bases we have used all the time are 
>> supposed to be orthonormal bases. We suppose that the scalar product (e_i 
>> e_j) = delta_i_j, when presenting the Born rule, and the quantum formalism.
>> 
>> Bruno
>> 
>> Generally, bases in a vector space are NOT orthonormal.
> 
> Right. But we can always build an orthonormal base with a decent scalar 
> product, like in Hilbert space, 
> 
> 
> 
>> For example, in the vector space of vectors in the plane, any pair of 
>> non-parallel vectors form a basis. Same for any general superposition of 
>> states in QM. HOWEVER, eigenfunctions with distinct eigenvalues ARE 
>> orthogonal.
> 
> Absolutely. And when choosing a non degenerate observable/measuring-device, 
> we work in the base of its eigenvectors. A superposition is better seen as a 
> sum of some eigenvectors of some observable. That is the crazy thing in QM. 
> The same particle can be superposed in the state of being here and there. Two 
> different positions of one particle can be superposed.
> 
> This is a common misinterpretation. Just because a wf can be expressed in 
> different ways (as a vector in the plane can be expressed in uncountably many 
> different bases), doesn't mean a particle can exist in different positions in 
> space at the same time. AG

It has a non null amplitude of probability of being here and there at the same 
time, like having a non null amplitude of probability of going through each 
slit in the two slits experience.

If not, you can’t explain the inference patterns, especially in the photon 
self-interference.




> 
> Using a non orthonormal base makes only things more complex. 
>> I posted a link to this proof a few months ago. IIRC, it was on its 
>> specifically named thread. AG
> 
> But all this makes my point. A vector by itself cannot be superposed, but can 
> be seen as the superposition of two other vectors, and if those are 
> orthonormal, that gives by the Born rule the probability to obtain the "Eigen 
> r

Re: Discrete theories of space

[Philip Thrift]

On Sunday, January 20, 2019 at 2:16:56 AM UTC-6, agrays...@gmail.com wrote:
>
>
>
> On Saturday, January 19, 2019 at 5:20:16 PM UTC, Philip Thrift wrote:
>>
>>
>>
>> On Saturday, January 19, 2019 at 5:42:12 AM UTC-6, agrays...@gmail.com 
>> wrote:
>>>
>>> Since it seems conceptually impossible to model a theory with DISJOINT 
>>> discrete spatial units, thus requiring the units to be juxtaposed, do such 
>>> theories acknowledge difficulty of motion between the units, which might or 
>>> might not have boundaries? TIA, AG
>>>
>>
>>
>> In quantum space or quantum spacetime approaches (like loop quantum 
>> gravity, casual dynamical triangulation), space or spacetime is in really a 
>> collection of 3D or 4D *cells *(tetrahedra or pentahedra) that are 
>> "glued" together somehow.
>>
>> There is no "space"  in the conventional Euclidean of Riemannian  
>> geometrical/metrical sense, so these cells aren't *in* space (there is 
>> no space inside of them or between them). The cells collectively *are* 
>> space.
>>
>> - pt
>>
>
> *I know. The alleged cells aren't IN space, but collectively ARE space.  
> But they can't be separated. If they were, light and material bodies would 
> have to traverse a Void of Nothingness to get anywhere. Motion would be 
> impossible. OTOH, if they're juxtaposed yet somehow distinguishable, they 
> would have to have boundaries, another big conceptual problem. I find the 
> idea of discrete spatial units, either juxtaposed or not, conceptually 
> unintelligible. AG*
>



What you just wrote (with words like "separated", "boundaries") is still 
presuming a background concept of space as some (x,y,z) coordinate entity 
as taught in school. (But see the Rovelli paper on the LQG "spinfoam" 
picture.)


Also apropos (regarding our preconception of space), the Immanuel Kant Song:

https://www.youtube.com/watch?v=DC8ioZkb-Sc

- pt


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Re: Discrete theories of space

[agrayson2000]

On Saturday, January 19, 2019 at 5:20:16 PM UTC, Philip Thrift wrote:
>
>
>
> On Saturday, January 19, 2019 at 5:42:12 AM UTC-6, agrays...@gmail.com 
> wrote:
>>
>> Since it seems conceptually impossible to model a theory with DISJOINT 
>> discrete spatial units, thus requiring the units to be juxtaposed, do such 
>> theories acknowledge difficulty of motion between the units, which might or 
>> might not have boundaries? TIA, AG
>>
>
>
> In quantum space or quantum spacetime approaches (like loop quantum 
> gravity, casual dynamical triangulation), space or spacetime is in really a 
> collection of 3D or 4D *cells *(tetrahedra or pentahedra) that are 
> "glued" together somehow.
>
> There is no "space"  in the conventional Euclidean of Riemannian  
> geometrical/metrical sense, so these cells aren't *in* space (there is no 
> space inside of them or between them). The cells collectively *are* space.
>
> - pt
>

*I know. The alleged cells aren't IN space, but collectively ARE space.  
But they can't be separated. If they were, light and material bodies would 
have to traverse a Void of Nothingness to get anywhere. Motion would be 
impossible. OTOH, if they're juxtaposed yet somehow distinguishable, they 
would have to have boundaries, another big conceptual problem. I find the 
idea of discrete spatial units, either juxtaposed or not, conceptually 
unintelligible. AG*

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