It’s good to focus on “General Relativity” and Cosmology without the cloak of mathematics gone wild and unsupervised, indeed.

Anything having to do with “General Relativity” has a lot of extremely debatable philosophy hidden below a thick carpet of computations. Abuse of philosophically unsupervised spacetime leads one to believe in time machines, wormholes, and similar absurdities. A recent discovery such as Dark Energy (ever expanding space faster than previously anticipated), and a not so recent one, Dark Matter, show one has to be extremely careful.

Einstein equation of “General Relativity” (GR) is basically Curvature = Mass-Energy. Einstein long observed that the left hand side of the equation was built of mathematical beauty, and the right hand side of a murky mud of a mess. The discovery of Dark Matter proved him prophetic about that. (BTW, I know perfectly well that, stricto sensu, it’s the Ricci tensor, derived from the full Curvature tensor on the left…)

First a philosophical trap: “General Relativity” (GR) is a misnomer. It’s not clear what’s being generalized. GR is certainly a theory of the relationship between gravity and local space-times (the Theory of Relativity of space and time which *Poincaré* named that way in 1904).

Einstein was initially motivated to explain inertia according to the Newton-Mach observation that the distant stars seemed to endow matter with inertia (because if matter rotates relative to distant stars, a centrifugal force appears).

That way, he failed, as Kurt Goedel produced spacetime models which rotated wildly without local consequences. Frame dragging exists nevertheless, and is crucial to GPS. So GR has local consequences.

Neither Poincaré nor Einstein liked the concept of “spacetime”.

A question has naturally come up: if space expands, how come we don’t? An answer to this has been the raisin bread model of the expanding universe.

As *Sabine Hossenfelder*, a theoretical physicist in Quantum Gravity and High energy physics puts it: *“In cosmology, too, it helps to first clarify what it is we measure. We don’t measure the size of space between galaxies — how would we do that? We measure the light that comes from distant galaxies. And it turns out to be systematically red-shifted regardless of where we look. A simple way to describe this — a space-time slicing that makes calculations and interpretations easy — is that space between the galaxies expands.”*

However, the entire area is contentious. The usual snap-back of haughty physicist keen to deny any brains worth noticing to the Commons, is to say that all those who don’t understand the mathematics at hand should shut up.

That’s a disingenuous answer, as NOBODY understands fully the mathematics at hand (those with snappy rejoinders know this, but they enjoy their power maliciously).

An example of the non-universality of the notion of expanding space is the following exact quote from Physics Nobel Laureate Steven Weinberg, author, among many other things, such as the Weinberg-Salam model of the electroweak interaction, of the most famous textbook on the subject, “Gravitation and Cosmology”: *“…how is it possible for space, which is utterly empty, to expand? How can nothing expand? The answer is: space does not expand. Cosmologists sometimes talk about expanding space, but they should know better”*

Well, they don’t.

Reference https://www.physicsforums.com/threads/raisin-bread-model-of-space-time.901290/

Personally, I think that both space and time are local concepts (as long as one does not add to consideration the Quantum theory, as it was created, post 1923, by De Broglie, and after 1924, by the Copenhagen School). Local space and local time are united by the speed of light, c, through naturally ubiquitous light clocks. Space and time are measured locally (although Poincaré proposed a slow motion to move synchronized clocks around, and Einstein copied and published that mechanism, verbatim, as he had with E = m c²).

It has been proposed that the redshift of cosmological photons, and its attribution, 100%, to the expansion of spacetime, is a proof of the expanding “spacetime”. One must say that this statement is the core of present cosmology. And anybody looking down on the idea will not be viewed as serious by famous physicists. However just saying something does not prove it. Especially when the conclusion seems to be the hypothesis.

Lorentz- Poincaré Local Space and Time theory was experimentally provable (electromagnetism proved it).

But where is the proof that the universe is like an expanding dough, spacetime, with galactic raisin grains in it? Just waving the notion that the atomic force is 10⁴⁰ the gravitation force at a small scale does not seem compelling to me. It’s rather a question of range: gravitation is much longer range, although, much weaker. Thus the geodesic deviations due to gravitation show up at a very great distance, whereas those due to atomic and molecular force cause enormous geodesic deviations, but only at very short range. We are these enormous local deviations, larger by 10⁴⁰ locally.

Yet, even this more precise argument smacks of hand waving. Why? Because a theory of local forces as curvatures, although posited by Riemann in 1865, and the foundation of GR, still does not exist (that’s one thing string theory was trying to achieve, and failed). Gravitation remains the only force that is tautologically equivalent to a curved space theory.

Quantum Physics has provided that theoretical spacetime with a nonlocal causal architecture (through Quantum Entanglement). However that “causality” although geometric, is non metric (and thus manifests itself with no geodesic deviation, no force).

Einstein, after a debate on nonlocality imparted by the Quantum, with the Austrian philosopher Karl Popper, attracted the world’s attention on that problem in 1935, with his famous EPR paper. There Einstein denounced the way the “spooky action at a distance” affected distant “elements of reality”. Since then, the spookiness at a distance has been amply confirmed (and enables to encrypt space communications while knowing 100% whether they have been breached, as a Chinese satellite recently showed). Nonlocal effects show unambiguously that the metric (of “spacetime”) does not capture all the geometry (an notion which may surprise physicists, but not those mathematicians who have studied the foundations of their field).

This Quantum architecture has led, so far, to no prophecy, let alone theory, by established physicist. Entangled Quantum architecture is actually not part of the General Relativistic raisin cake model (or any GR model). However, I will venture to say one can view it as predicting Dark matter, at the very least. It’s just a question of baking something more sophisticated than raisin bread.

Patrice Ayme

Tags: Expansion, Local Versus Global, Raisin Bread, Spacetime

August 5, 2017 at 1:41 am |

Patrice,

The problem I keep pointing out is that saying redshift is evidence of expanding space overlooks the fact this assumes a constant speed of light across that intergalactic distance, because if the light is redshifted, it means it is taking longer as the distance grows. The units measured by the speed of light, aka lightyears, are not expanding, there are presumably more of them. That is what causes redshift!

The reply I get is that the speed of light is only measured locally, but it is comparing the speed and spectrum of the VERY SAME INTERGALACTIC LIGHT!!!!

As Einstein said, “Space is what you measure with a ruler.” And the cosmic ruler is the speed of light. That is not local. If there are more lightyears between two points, that isn’t expanding space, but an increasing amount of stable space.

August 5, 2017 at 6:39 am |

Brodix: All textbooks will tell you the speed of light doesn’t depend upon its frequency. Visible light goes at the same speed as radio waves. So you are wrong on that.

More stable space is what Weiner seems to be saying?

August 5, 2017 at 7:43 am |

Correct on both points. More later!

August 5, 2017 at 10:40 am |

Gmax,

The point is the cosmic redshift is still about doppler shift. Consider the theory says all of space began as a point and expanded from there. Given the visible universe is many billions of lightyears across, did it take billions of years for light to cross that point?

Did the speed of light remain constant to this initial distance, or has the distance increased and it takes light longer to cross?

If the speed of light did remain constant to this initial space, such that the speed of light increases, as the space expands, why would it redshift?

If everything is moving apart and the light is taking longer to cross between galaxies, what is this vacuum through which light travels at C, if it isn’t the same space expanding between galaxies?

August 5, 2017 at 7:59 pm |

Patrice made a big point once that the universe didn’t start necessarily as a point, she lashed out at Ethan Siegel for sayING that. Siegel is an astrophysicist who writes for Forbes.

Nobody knows what the vacuum is made of

August 5, 2017 at 8:23 pm |

Yeap, see answer to Brodix. Nature of vacuum is unknown, although lots of weird stuff is known…

August 5, 2017 at 9:09 pm |

Gmax,

Aside all the unknowns, there is a basic logical contradiction in the theory.

Way back when they realized all those galaxies are redshifted proportional to distance, they realized this made it appear as though we are at the exact center of the universe, so rather than assuming it is a simple expansion of matter, in space, the argument became, based on the premise of spacetime, that space itself is expanding and so every point appears as the center.

But this still assumes the redshift is due to recession, i.e. the other galaxies are moving away.

Yet one of the central premises of GR is that the speed of light in a vacuum is a constant, but if the light is redshifted because it is taking longer to cross, as the source recedes, then it is not constant.

The cosmic ruler is the speed of light, i.e., lightyears. If there are more lightyears between galaxies, that is not expanding space, but increasing distance, in stable space.

We are at the center of our view of the universe, so an optical explanation for redshift might be worth considering.

August 5, 2017 at 9:37 pm

The cosmic LCDM redshift is caused by space expansion. It’s not a Doppler shift (although often presented that way by people who know better!!!!)

Taking longer to cross doesn’t shift to the red. Only space expansion does this.

In my own theory, lots of the redshift is caused by (cosmic) fatigue of the light, itself a Quantum effect. Same effect created Dark Matter and Dark Energy…

August 5, 2017 at 8:21 pm |

Big Bang Cosmology, the LCDM model, requires the universe to start with a singularity in time, not space.

Speed of light not constant: Dirac pondered that one. There no answer. LCDM assumes a constant speed of light. Ironically GR does not…

Lots to say on the vacuum. Actually clearly the Casimir effect shows that the vacuum depends upon boundary conditions. However, GR has no boundary conditions.

Lots of GR would make more sense if math advanced. One argument of mine is that “spacetime”, or, at least space can be embedded in higher dimensional euclidean space. However I didn’t write down the proof in detail… There are caveats:

http://www.mathpages.com/home/kmath342.htm

August 5, 2017 at 7:42 am |

There are indeed problems about the one way speed of light. That was pointed out explicitly by the philosopher of science Reichenbach, nearly a century ago. But Poincare’ I think at the argument already by 1904… Hence his general caution in the area. Einstein too was cautious and he heaped contempt on “spacetime”.

As Gmax said, the speed of light is independent of frequency. My general mood here is that, indeed, some of the whole cosmological picture may well be false (as contradiction between physicists indicate)!

August 5, 2017 at 2:47 am |

To say that curvature equals energy introduces an interesting problem with dimensions.

Having said that, one issue for me is that I can accept that spacetime is a useful tool for solving the equations of GR, but just as using Cartesian coordinates is useful but does not imply that there is something physical there, why does everyone assume that spacetime is something. (Especially bad from my point of view is the wretched “heavy body on a trampoline” view).

August 5, 2017 at 7:37 am |

I think that’s what Weinberg is saying. The counter-argument is virtual particles, and the counter to that in turn is that virtual particles aren’t real. The counter of the counter to the original counter is first that “real particles” are not really real either, and secondly, but most importantly virtual particle effects are real: consider the Casimir effects and their consequence, Van de Waala forces… That is, chemistry…

The point of my essay is that there is a problem: when one looks at a super giant galactic clusters, it’s clear the argument that the space within the clusters does not expand is not clear…

August 5, 2017 at 6:30 am |

Pretty astounding contradiction between Sabine H and Steven W! What you seem to be saying it that physicists routinely claim as a basic proof that space within galactic clusters don’t expand an argument they have not computed in details?

Loved the ctenophores essay too. We need more of these mind expanding facts

August 6, 2017 at 1:58 am |

Those “raisins” are galactic vortices and Einstein described gravity as collapsing space. Because of this, he felt compelled to add a “cosmological constant” to explain why the entire universe isn’t collapsing.

It is my suspicion that Hubble actually found this CC, as the radiological expansion of the measure of space, between galaxies, to balance the gravitational and mass contraction of the measure of space into them. Resulting in what amounts to a cosmic convection cycle.

Possibly the explanation for “dark matter” is this process of contraction goes all the way back to the quantification of light, so much of this attraction is in the radiological spectrum, rather than the mass spectrum.

A couple of interesting links;

The loading theory of light;

http://fqxi.org/data/essay-contest-files/Reiter_challenge2.pdf

The redshift of multi spectrum light packets;

http://fqxi.org/data/forum-attachments/2008CChristov_WaveMotion_45_154_EvolutionWavePackets.pdf

If one assumes light traveling for billions of years, over billions of trillions of miles(lightyear=trillion miles) doesn’t do it as individual photons, but as waves and the quantization of light is a function of its absorption, the above would explain why the light from distant galaxies is redshifted, as an optical effect. Just as gravitational curvature of light is optical.

August 6, 2017 at 5:55 am |

Thanks for the links, Brodix, very interesting.

It’s true that both papers address MANY issues which have not been fully addressed.

However, QUANTUM theory is proven beyond dispute. That fight of Quantum versus loading was Einstein versus Planck. Einstein got the Nobel mostly for that (the Nobel committee said, 95 years ago, or so). Einstein’s idea was tiny, but strong: he just SYMMETRIZED logically, Planck’s quantization of energy transfer upon emission. I can understand Planck’s got infuriated not to have thought of it, because it was a tiny add-on, relative to Planck’s formidable work.

Reiter also complain about the linear guiding wave theory (the De Broglie theory). That theory is an attempt at what I call SUB Quantum theory. Official Quantum theory brushes all and any related considerations below the logical carpet. So If Reiter criticizes Quantum, it’s unfair to criticize SUB Quantum De Broglie.

Now for the wave packet link: present theory has a problem dealing with single photons. Single photons can’t be packets, but only packets have a beginning and an end. There one is immediately into SUB Quantum questions. Questions, not answers. Hard core theorists all avoid those subject scrupulously. Nowadays. Perhaps everybody is afraid of what happened to De Broglie and Bohm?

Calling the deviation of geodesics “optical” is interesting, but it’s admitting the obvious: in Relativity, light is THE FOUNDATION (because Lorentz and Poincare’ made it so, correctly!!!!) So light follows geodesics. In a way ALL Relativity is “optical”! So is the Quantum, as the usage of complex numbers reflects light polarization: complex numbers incorporate rotation.

In any case, the human eye detects single photons. Single photons are not packets. What happened to a cosmic photon is unknown to me (and the others too, although some may not admit so)

August 6, 2017 at 1:10 pm |

Patrice,

Obviously this is not my territory and expertise, so only thankful if I can make a few connections.

That said, even I can sense there are significant problems that are being lost in professional politics.

It was only through interest in how society functions, that I got into physics, by way of philosophy, so finding the field dominated by politics opens some basic, familiar insights. Such as that as reality is fundamentally non-linear and only tactically linear, thermodynamics is a more basic expression of the process, than time. Which is an effect of change, by which future becomes past.

So upon reading way back when that the expansion of the universe is inversely proportional to the contraction of gravity, the relationship made sense to me as a cosmic convection cycle, of expanding radiation and collapsing mass. Through all the bits of theories, blowing in the wind, I find this view still holds.

I am holding out hope the James Webb space telescope will find structures to make the age restrictions of the current model untenable, opening up the field to different ideas.

August 7, 2017 at 10:30 am |

Patrice, Gmax,

To get back to this, yes, it is argued that space expands, as light crosses it, but there are still two metrics being compared.

The analogy of the inch worm crossing an expanding balloon is a useful example. What determines the pace of the inch worm? As in what is this vacuum through which light travels at C, if it isn’t space?

As such one is the denominator and the other is the numerator.

Consider that when this was first being considered, the alternative theory was “tired light.” That the speed of light was somehow being slowed, but this was rejected because nothing was distorting the light.

So in that relationship, space was considered neutral and the speed of light was slowed. Which made space the denominator and the speed of light the numerator.

While in the expanding space theory, it is the speed of light that is assumed to be neutral and space which is expanding. so it would make the speed of light the denominator and space the numerator.

Which would make the speed of light the ruler, as Einstein put it.

August 7, 2017 at 9:26 pm |

It was discovered by Lorentz and Poincare’ that all what matters is the equations of electromagnetism, which implied equations for local spacetime. The nature of spacetime couldn’t be revealed, and was irrelevant. Einstein duplicated the reasoning which he got from Poincare’ “Science et Hypothese”.

By definition, light goes at c.

To speak of the speed of light absolutely: an idea of mine is to embed everything in a larger Euclidean space, but the math are obscure because spacetime is an NON Riemannian pseudo manifold. I don’t have the time to do the math. Nobody would care, anyway… And they would be WRONG… Whether virtual particles are, after all, real, is a more interesting subject…

August 8, 2017 at 1:38 am |

Patrice,

Consider the math of a geocentric universe is perfectly valid, because we are the center of our point of view of the universe and so it can logically be mathematically modeled. The problem was the physical explanation, epicycles, giant cosmic gearwheels of the clockwork universe, was a direct projection of this model. Just as spacetime is a direct projection of the math of Relativity.

Time is not a dimension. It is an effect, like temperature. Past and future cannot physically exist because all energy is conserved as the present state. That it is changing form creates the effect of time.

Just as we still see the sun rising in the east and setting in the west, we experience time as the point of the present moving from past events to future ones, but that is the opposite of what happens, change turning future to past. Just as it is really the earth turning west to east.

August 8, 2017 at 7:13 pm |

Time in Relativity, a dimension is mathematically different from time in Quantum Physics, a one parameter group of operators. So I don’t disagree with what you say…Different natures of time in different realms of physics show that physics is far from being coherent, let alone complete

August 8, 2017 at 9:00 pm |

A neurologist’s view;

https://www.newscientist.com/article/2132847-your-brain-is-a-time-machine-why-we-need-to-talk-about-time/?utm_campaign=Echobox&utm_medium=Social&utm_source=Twitter#link_time=1496743708

August 9, 2017 at 7:44 am

Very interesting, thanks for the link…

However, mentioning the “BLOCK universe” (I don’t know what it is) and puzzling about “Relativity of Simultaneity” from Poincare’ Relativity, at last, says the author, natural from the “BLOCK universe”is, well grandiose, but empty.

I have studied Relativity for decades. Relativity of simultaneity is as natural for me as Relativity of thunder. And the “BLOCK universe” is another way of talking about spacetime with time loops, something I don’t believe in (nor did Poincare’ and Einstein, I strongly suspect; although this outrageous subject didn’t occur in their… time…)

Pop science ain’t science, but it sells well…

August 10, 2017 at 1:40 am |

Patrice,

Time is reduced to a measure of duration between events, on the assumption it is “movement” from past to future and duration is the “dimension” between events, just as distance(measure of a single dimension of space) is between two points in space.

Yes, there is no real clarification, or specification of what this underlaying dimension of duration signifies.

I keep pointing out duration is the state of the present, as events unfold, i.e. coalesce out of potential and fade into residual, going future to past.

As such, it is an effect of activity in this physical state. Making it more in common with temperature, than space.

Occurrence is the process of calculating the total input into an event, so that occurrence yields determination. Events are first present, then past.

Viewing it as a flow from past to future has caused science to either project past determination onto future possibilities, aka determinism, or project future possibilities onto past outcomes, aka Everett multiworlds(worldlines split by the non-collapse of probabilities), because there is little conceptual distinction between past and future, so they are projected onto each other.

August 10, 2017 at 10:26 am

The art of physics comes down to computations (now on computer). You should study Quantum Time as found in elementary Quantum Mechanics (not QED and QFT, where it’s more traditional aslong as one multiplies if by i…)