Re: CMBR and Horizon Problem
On Wednesday, December 26, 2018 at 2:37:59 AM UTC, Brent wrote: > > > > On 12/25/2018 4:42 PM, agrays...@gmail.com wrote: > > > > On Tuesday, December 25, 2018 at 11:26:14 PM UTC, Brent wrote: >> >> >> >> On 12/25/2018 8:01 AM, agrays...@gmail.com wrote: >> >> >> >> On Tuesday, December 25, 2018 at 1:16:53 PM UTC, John Clark wrote: >>> >>> On Mon, Dec 24, 2018 at 3:21 PM wrote: >>> >>> >> You can never prove that any physical quantity is exactly zero, but > we do know from observations of the cosmic microwave background radiation > that if the universe is curved at all it is by less than one part in > 100,000. > >>> >>> *> Agreed. However, IMO the observed universe cannot be flat with exactly zero curvature (which I refer to as "mathematically flat) since that would imply infinite volume * >>> >>> If information can't travel faster than light then by definition the >>> radius of the spherical volume of the universe you can observe can't be >>> larger than the age of the universe in years times a light year. >>> >>> *> **which contradicts its finite age.* >>> >>> There is no reason spacetime couldn't extend a finite distance into the >>> past but an infinite distance into the future. >>> >> >> *The observable universe could continue to expand forever, but it always >> has a finite radius. We have no information about the unobserved part, so >> it could be any size, maybe even tiny. AG* >> >> >> All of those inferences are based on the universe obeying Friedman's >> equations, i.e. Einstein's equations for a homogeneous, isotropic >> universe. So they are inconsistent with the unobserved part of the >> universe obeying some other conditions. Whether there is a solution with >> the observable patch being different from the unobservable part is an open >> question. If you find one, publish it. But you can't just assume that >> because there's an unobserved part that it could be anything. >> > > *If we don't know anything about the unobservable part of the universe, it > could obey any conditions; maybe consistent with the Friedman's equations, > maybe not. I was just saying we can't assume anything. AG* > > > And I'm saying you can't say the observable part of the universe satisfies > the Friedman equations and the rest of can be anything. That the rest of > the universe is constrained by what the observable part is like is a > consequence of Einstein's equations. Could Einstein's equations be wrong? > Sure they could, but they've passed every test, so applying them is not an > assumption. > *I concur. Using the Cosmological Principle, one would expect the unobservable region to obey the same or similar laws as the observable region. What's your view of whether inflation solves the flatness problem? TIA, AG* > > Brent > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
Re: CMBR and Horizon Problem
On 12/25/2018 4:42 PM, agrayson2...@gmail.com wrote: On Tuesday, December 25, 2018 at 11:26:14 PM UTC, Brent wrote: On 12/25/2018 8:01 AM, agrays...@gmail.com wrote: On Tuesday, December 25, 2018 at 1:16:53 PM UTC, John Clark wrote: On Mon, Dec 24, 2018 at 3:21 PM wrote: >> You can never prove that any physical quantity is exactly zero, but we do know from observations of the cosmic microwave background radiation that if the universe is curved at all it is by less than one part in 100,000. /> Agreed. However, IMO the observed universe cannot be flat with exactly zero curvature (which I refer to as "mathematically flat) since that would imply infinite volume / If information can't travel faster than light then by definition the radius of the spherical volume of the universe you can observe can't be larger than the age of the universe in years times a light year. *> */which contradicts its finite age./ There is no reason spacetime couldn't extend a finite distance into the past but an infinite distance into the future. *The observable universe could continue to expand forever, but it always has a finite radius. We have no information about the unobserved part, so it could be any size, maybe even tiny. AG* All of those inferences are based on the universe obeying Friedman's equations, i.e. Einstein's equations for a homogeneous, isotropic universe. So they are inconsistent with the unobserved part of the universe obeying some other conditions. Whether there is a solution with the observable patch being different from the unobservable part is an open question. If you find one, publish it. But you can't just assume that because there's an unobserved part that it could be anything. *If we don't know anything about the unobservable part of the universe, it could obey any conditions; maybe consistent with the Friedman's equations, maybe not. I was just saying we can't assume anything. AG* And I'm saying you can't say the observable part of the universe satisfies the Friedman equations and the rest of can be anything. That the rest of the universe is constrained by what the observable part is like is a consequence of Einstein's equations. Could Einstein's equations be wrong? Sure they could, but they've passed every test, so applying them is not an assumption. Brent -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
Re: CMBR and Horizon Problem
On Tuesday, December 25, 2018 at 11:26:14 PM UTC, Brent wrote: > > > > On 12/25/2018 8:01 AM, agrays...@gmail.com wrote: > > > > On Tuesday, December 25, 2018 at 1:16:53 PM UTC, John Clark wrote: >> >> On Mon, Dec 24, 2018 at 3:21 PM wrote: >> >> >> You can never prove that any physical quantity is exactly zero, but we do know from observations of the cosmic microwave background radiation that if the universe is curved at all it is by less than one part in 100,000. >>> >> >> *> Agreed. However, IMO the observed universe cannot be flat with exactly >>> zero curvature (which I refer to as "mathematically flat) since that would >>> imply infinite volume * >>> >> >> If information can't travel faster than light then by definition the >> radius of the spherical volume of the universe you can observe can't be >> larger than the age of the universe in years times a light year. >> >> >>> *> **which contradicts its finite age.* >>> >> >> There is no reason spacetime couldn't extend a finite distance into the >> past but an infinite distance into the future. >> > > *The observable universe could continue to expand forever, but it always > has a finite radius. We have no information about the unobserved part, so > it could be any size, maybe even tiny. AG* > > > All of those inferences are based on the universe obeying Friedman's > equations, i.e. Einstein's equations for a homogeneous, isotropic > universe. So they are inconsistent with the unobserved part of the > universe obeying some other conditions. Whether there is a solution with > the observable patch being different from the unobservable part is an open > question. If you find one, publish it. But you can't just assume that > because there's an unobserved part that it could be anything. > *If we don't know anything about the unobservable part of the universe, it could obey any conditions; maybe consistent with the Friedman's equations, maybe not. I was just saying we can't assume anything. AG* > > Brent > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
Re: CMBR and Horizon Problem
On 12/25/2018 8:01 AM, agrayson2...@gmail.com wrote: On Tuesday, December 25, 2018 at 1:16:53 PM UTC, John Clark wrote: On Mon, Dec 24, 2018 at 3:21 PM > wrote: >> You can never prove that any physical quantity is exactly zero, but we do know from observations of the cosmic microwave background radiation that if the universe is curved at all it is by less than one part in 100,000. /> Agreed. However, IMO the observed universe cannot be flat with exactly zero curvature (which I refer to as "mathematically flat) since that would imply infinite volume / If information can't travel faster than light then by definition the radius of the spherical volume of the universe you can observe can't be larger than the age of the universe in years times a light year. *> */which contradicts its finite age./ There is no reason spacetime couldn't extend a finite distance into the past but an infinite distance into the future. *The observable universe could continue to expand forever, but it always has a finite radius. We have no information about the unobserved part, so it could be any size, maybe even tiny. AG* All of those inferences are based on the universe obeying Friedman's equations, i.e. Einstein's equations for a homogeneous, isotropic universe. So they are inconsistent with the unobserved part of the universe obeying some other conditions. Whether there is a solution with the observable patch being different from the unobservable part is an open question. If you find one, publish it. But you can't just assume that because there's an unobserved part that it could be anything. Brent -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
Re: Are you smarter than a 5th grade amoeba?
I realized this when it turns out that ants can solve a similar NP problem linearly or nearly P when it comes to setting up their tracks. LC On Saturday, December 22, 2018 at 8:09:39 PM UTC-6, Brent wrote: > > Bruno should enjoy this. > > Brent > > > Forwarded Message > > This is a cool bio hack, but is this approach ever going to be faster > and/or cheaper than an electronic computer for the same precision of > optimization? > > > https://phys.org/news/2018-12-amoeba-approximate-solutions-np-hard-problem.html > > > Amoeba finds approximate solutions to NP-hard problem in linear time > > December 20, 2018 by Lisa Zyga, Phys.org > > Researchers have demonstrated that an amoeba--a single-celled organism > consisting mostly of gelatinous protoplasm--has unique computing > abilities that may one day offer a competitive alternative to the > methods used by conventional computers. > > The researchers, led by Masashi Aono at Keio University, assigned an > amoeba to solve the Traveling Salesman Problem (TSP). The TSP is an > optimization problem in which the goal is to find the shortest route > between several cities, so that each city is visited exactly once, and > the start and end points are the same. > > https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.180396 > > Remarkable problem-solving ability of unicellular amoeboid organism > and its mechanism > > Choosing a better move correctly and quickly is a fundamental skill of > living organisms that corresponds to solving a computationally > demanding problem. A unicellular plasmodium of Physarum polycephalum > searches for a solution to the travelling salesman problem (TSP) by > changing its shape to minimize the risk of being exposed to aversive > light stimuli. In our previous studies, we reported the results on > the eight-city TSP solution. In this study, we show that the time > taken by plasmodium to find a reasonably high-quality TSP solution > grows linearly as the problem size increases from four to eight. > Interestingly, the quality of the solution does not degrade despite > the explosive expansion of the search space. Formulating a > computational model, we show that the linear-time solution can be > achieved if the intrinsic dynamics could allocate intracellular > resources to grow the plasmodium terminals with a constant rate, even > while responding to the stimuli. These results may lead to the > development of novel analogue computers enabling approximate solutions > of complex optimization problems in linear time. > > > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
Re: "No black-hole singularities" in an undated loop-quantum-gravity theory
The singularity of a black hole represents a change in phase of a system.
The path integral defines states of the form
|ψ> = Z|0> = ∫D[φ]q e^{-iH(φ)t/ħ}|0>.
The partition function in statistical mechanics is of the form
Z = sum_n e^{-E_nβ}.
The primary differences are the partition function is Euclidean and
discrete, while path integrals are complex valued and for continuous fields
are themselves continuous. Let us consider the Ising model of spins with H
= κσ_iσ_j. The partition function may then be thought in the manner
Onsanger considered as
Z = sum_{ij} e^{-|i – j|ξ(β)},
where ξ(β) = (β - β_c)^n. Here β_c represents a critical temperature
1/kT_c. The system is discrete since the Hamiltonian operates for nearest
neighbor interactions. However for β = β_c the range expands “to infinity”
and the system is continuous in that limit. This occurs at a phase change.
We may then compare this to the hypothesis that spacetime is built up from
quantum entanglements. At the critical phase entanglements are entirely
nonlocal and the path integral, or in the Euclidean sense, is continuous.
The connection between the two is that ξ(β) = τ/ħ for τ = it a
Euclideanized time. At ξ(β) = 0 there is a quantum critical point and in
the setting of entanglements and spacetime what we think of as a continuous
spacetime is then defined.
It is better to consider the Reissnor-Nordstrom or Kerr-Newman black hole
with the outer and inner horizons
r_± = m ± sqrt{m^2 - a^2cos^2θ}.
The ring singularity occurs for r = 0 and θ = 0 or in Cartesian coordinates
a^2 = x^2 + y^2. The departure from spherical coordinates and Cartesian
coordinates is an oddity of spacetime being so twisted up in this region.
The outer ergosphere occurs at r = 2m, there is also an inner horizon that
occurs at r = a cosθ, This inner ergosphere is continuous with the ring
singularity at θ = 0. The region bounded by the inner ergosphere is where
timelike geodesics are forced into closed loops. These closed timelike
loops are then associated with a monodromy induced by a phase where
spacetime breaks down.
[image: Kerr-surfaces.png]
Dafermos and Luk found that within the inner horizon there is a breakdown
in uniqueness conditions for solution https://arxiv.org/abs/1710.01722 .
This is because within this region geodesics may be timelike, and within
the inner ergosphere they are constrained to be closed. I will confess to
have not as yet read their entire paper, as it is a long tome with rather
dense mathematics. However, the result appears at least commensurate with
the hypothesis that spacetime as understood in general relativity becomes
less defined.
Closed geodesics occur in anti-de Sitter spacetime as well. I have found a
homomorphism between black hole horizon states and states in AdS or
equivalently CFT states on the boundary. This interestingly is defined with
a form of the Riemann ζ-functions that give eigenvalues. The AdS_{n+1} has
in general topology S^1×R^n for S^1 timelike. Scott Aaronson have found
that closed timelike loops for quantum computers solve NP problems, and in
fact appear to cover all of P-SPACE https://arxiv.org/pdf/0808.2669.pdf .
The diagram illustrates this
[image: quantum computer with closed timelike curves.png]
There are then two registers of qubits R_{cr} that is causality respecting
and R_{ctc} for qubits on closed timelike paths. The closed timelike curves
in the path integral provide constructive and destructive interference of
the wave function that is NP. There is evidence the zeros of the Riemann
ζ-function is of a geometric complexity class that is NP
https://www.youtube.com/watch?v=Nn4B-9YspuI . The quantum eigenstates of
gravity are then “computed” by closed timelike paths in a path integral,
but where observers only have direct access to qubits in the R_{cr}.
LC
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Re: CMBR and Horizon Problem
On Tuesday, December 25, 2018 at 1:16:53 PM UTC, John Clark wrote: > > On Mon, Dec 24, 2018 at 3:21 PM > wrote: > > >> You can never prove that any physical quantity is exactly zero, but we >>> do know from observations of the cosmic microwave background radiation that >>> if the universe is curved at all it is by less than one part in 100,000. >>> >> > > *> Agreed. However, IMO the observed universe cannot be flat with exactly >> zero curvature (which I refer to as "mathematically flat) since that would >> imply infinite volume * >> > > If information can't travel faster than light then by definition the > radius of the spherical volume of the universe you can observe can't be > larger than the age of the universe in years times a light year. > > >> *> **which contradicts its finite age.* >> > > There is no reason spacetime couldn't extend a finite distance into the > past but an infinite distance into the future. > *The observable universe could continue to expand forever, but it always has a finite radius. We have no information about the unobserved part, so it could be any size, maybe even tiny. AG* > > John K Clark > > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
Re: CMBR and Horizon Problem
On Mon, Dec 24, 2018 at 3:21 PM wrote: >> You can never prove that any physical quantity is exactly zero, but we >> do know from observations of the cosmic microwave background radiation that >> if the universe is curved at all it is by less than one part in 100,000. >> > *> Agreed. However, IMO the observed universe cannot be flat with exactly > zero curvature (which I refer to as "mathematically flat) since that would > imply infinite volume * > If information can't travel faster than light then by definition the radius of the spherical volume of the universe you can observe can't be larger than the age of the universe in years times a light year. > *> **which contradicts its finite age.* > There is no reason spacetime couldn't extend a finite distance into the past but an infinite distance into the future. John K Clark -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
Re: What is more primary than numbers?
On Monday, December 24, 2018 at 5:54:41 PM UTC-6, agrays...@gmail.com wrote:
>
>
>
> On Monday, December 24, 2018 at 1:16:36 PM UTC, Bruno Marchal wrote:
>>
>>
>>
>>>
>>> The SE remains always correct. It is only if you make the other
>>> “universe" disappearing that the SE is not correct.
>>>
>>
>> *BS. You utterly fail to understand the point of the horse race example.
>> The SE doesn't extend to other worlds. *
>>
>>
>> ?
>>
>> The SE is what define the other worlds, or superposition terms, and the
>> SE describes them literally. The double linearity (tensor product and
>> evolution) makes the SE describing the prediction relatively to each
>> branch. The collapse of the wave is a non linear process (if it is seen as
>> a process) violating the SE.
>>
>
> *You insist that everything that's possible to happen, must happen.
> Nothing to support this idea but your bias. In a horse race, you are
> demanding that universes are created in which each horse wins. Do you
> really think this is how the universe functions? As for the SWE, you've
> imposed your will on where it applies, and appeal to the non linearity of
> the collapse process to justify your preference. But there ARE non linear
> processes in nature. So your claim is poorly based. AG*
>
>>
>> Many-worlds (or many-histories, …) is basically just the SWE, without
>> collapse. Everett theory is just Copenhagen minus the idea of a physical
>> collapse.
>>
>> *Those who claim otherwise are adding something to QM which suits their
>> fancy; that everything that's possible to happen, must happen.*
>>
>> Only with a special probability, and relatively to the observer.
>> Yes, that “everything” needs to be realise, or we don’t get the
>> interference.
>>
>
> *I don't see why interference depends on everything happening. The many
> universes you claim come into existence when a single outcome occurs, are
> disjoint. So it's hardly obvious why the interference observed over many
> outcomes Iin our universe, depends on these other universes. AG *
>
>>
>>
I great book title for quantum reality ("Timeless Reality" was the title of
Victor Stenger's book) would be
"Don't Make Waves".
The wave function is one of the worst ideas to ever enter physics.
- pt
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