LIGO scientists row back on claim to detect black-holes from their gravitational signal

It is gradually coming out that LIGO’s main gravitational wave pulse could indicate various types of binary astrophysical systems, as we said on this blog in February. Cardoso et al 2016 point out (Phys Rev Lett. to come) there are compact objects that are not black holes, including gravastars of similar dimensions (~30 solar masses) which produce a similar main signal. The late part of the signal was below detection threshold, and that is needed to distinguish between astrophysical objects. In discussing this, Physics World quotes Prof Sathyaprakash from Cardiff’s LIGO team saying that “Our signal is consistent with both the formation of a black hole and a horizonless object – we just can’t tell.” Rather different from him in the Guardian of 11 Feb. “The fusion of two black holes created this event”. Now, Remo Ruffini (of the Rees-Ruffini-Wheeler textbook) co-authors an preprint (16 May 2016) saying: unfortunately the signal of the merging “occurs just at the limit of the sensitivity of LIGO (so is) not sufficient to determine the astrophysical nature of GW 150914, nor to assess that it was produced by a binary black-hole merger leading to a newly formed black-hole.”

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Gravitational wave event at last – success for Einstein, not black-holes

Detecting gravitational waves after decades of searching and developing more sensitive techniques is a great achievement, in technology as well as the accompanying analysis.

What a pity the research teams have sullied the discovery by conflating the detection of a very clear gravitational wave signal with their particular interpretation.  Doubtless the big signal over milliseconds implies very large condensed masses interacting cataclysmically, inferred to be over 25 solar masses. The event had to be relatively close to us in space to give a signal well above numerous extragalactic ones.  The teams apply their model for two ‘black holes’ merging, as if it’s the sole contending explanation. The model merging scale is the Schwarzschild radius MG/c2, not of point-like black holes. Megamassive condensed stars (largely of neutrons) are of this scale too.  The rapid merging two of them would generate a similar signal, if with differences in detail.  This was dismissed simply on the basis of the out-dated belief that neutron stars can be no bigger than 2 solar masses (Ms).

Einstein himself did not believe in Black Holes; physicists should at least accord him respect in allowing that this first clear gravitational wave event implies the sudden rebalancing of large condensed masses, probably a merging binary – to give his quadrapole emissions – and opens up a way to investigate such structures.  The big majority of the gravitational energy pulse comes out from the mutually orbiting stars (rapid, up to ~0.5c) as they become increasing close in last second before becoming one.  Open-minds are especially required when black-hole modelling uses a faulty metric, having a non-physical region beyond a ‘surface of separation’, which requires dodgy computational treatments.

The discovery kills off the notion that gravitational energy is non-localised. The observed pulse was tightly constrained in time, ~10ms scale.  The pulse moves through space with the speed of light, akin to electromagnetic waves, not through “space-time” as is confusingly said.  Both electromagnetic and gravitational equations have wave solutions to small perturbations – travelling waves that carry energy – as Einstein first predicted, though not dipole but of quadrupole order for gravitational waves.

The inference of large compact masses – neutron stars of tens of solar masses – is an indirect discovery of an unrecognised population of mega-stars that are indeed predicted from the Hilbert-Einstein equations of General Relativity.  These can be neutron stars above the so-called TOV size limit of 2.0Ms given by Cameron (1959); our modelling given at the recent Moscow PIRT conference (link here) finds higher mass ‘gravastar’ structures, ie. shell-stars of compact matter with centres dominated by hypergravitational fields.

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Einstein not to blame for the Flow-of-Time deviation

comment on Saving time: Physics killed it. Do we need it back?  

New Scientist feature 01 November 2013 by Michael Slezak

It’s unfair to blame Einstein for the ‘fatal blow’ to the ‘flow of time’, which some physicists still find problematic.  Lee Smolin argued recently (26 April 2013) that the blows were never fatal.

The source of the trouble is the time-reversible formulations of ‘laws’ of physics, such as Newton’s laws. Einstein’s special relativity showed clock-timing is not unique, but did retain the time-sequence that is essential for causality – a principle that Einstein stoutly defended.

Einstein also advocated the Faraday-Maxwell concept of space-filling fields, and extended the differential equations for their field-borne light waves to apply to field-borne gravity waves.

However, these time-reversible formulations are not the whole story. Light-rays reach us only from the past, not the future. The time-explicit formulation of light waves uses (Liénard-Wiechert) retarded potentials to form an integral over waves reaching each point from earlier times. This integral satisfies both Maxwell’s time-reversible equations and the Penrose criterion that a truly fundamental law of physics is irreversible.

Thus the difficulty of standard physics with the ‘flow of time’ arises because it tries to dispense with fields of force, presuming they can be represented by particles (‘photons’, ‘gravitons’) governed by reversible interactions. Physics has to return to fields, carrying waves at the speed of light (following Einstein’s special relativity) to recover common sense over passage of time.

Einstein’s much quoted phrase “the distinction between past, present, and future is only a stubbornly persistent illusion” was written 3 weeks before his death and months after he’d expressed doubts about his whole life’s work including gravitation “based on the field principle”.  Evidently, the Einstein in 1955 was failing fast, had lost confidence and influence as a physicist, and his weak blow to the flow of time has proved non-fatal.

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Why Space has Three Dimensions

Why Space has Three Dimensions   – see Matthew Chalmers, New Sci 28 Sept 2013

That space is 3-D follows from electromagnetic and gravitational theory, both being experimentally validated and both free of quantum theory’s offence to views of reality (Chalmers, NS 28 Sept, p.34).

The reasons are surely much deeper than the inverse square ‘law’ (argument in the Box).

First, accelerated charges emit synchrotron radiation in a beam relative to the inertial reference frame of special relativity, of 3-space plus time.

Second, Einstein’s general relativity gives slightly different answers for light travel times (eg. Earth to Venus) for different accelerated frames – a unique answer comes by specializing to the inertial frame.

Einstein’s strong form of the “equivalence principle” led him astray, in that it took accelerated frames as equally valid, rejecting a unique space frame. His followers like Fock, Weinberg and Logunov have found good reasons for the inertial frame and thus for 3-space being real.

Seeing 3-space as real and higher dimension spaces as mathematical models, thus implies a weak form of the equivalence principle, applying locally, eg. in Einstein’s lift, but not in rotating planetary systems.

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Not only time is real, but space too!

Comment on “Time Reborn: from the crisis in physics to the future of the universe”

Time is real, okay! A time-sequence is essential for the causality principle. Good that Lee Smolin comes out against “laws of physics” that take time to be an illusion. We know the laws are man-made. As he writes, light-rays reach us only from the past, not the future, so the ‘laws’ should encompass this.

The time coordinate in Maxwell’s electromagnetic theory is different from the 3 space coordinates. The beauty of the 4-vector differential formulation, with ‘imaginary’ time the 4th coordinate, has led people astray.

The time-explicit formulation of light waves uses (Liénard-Wiechert) retarded potentials to form an integral over waves reaching each point from earlier times. This satisfies the Penrose criterion for a truly fundamental law being irreversible, unlike the differential equations of Maxwell.

If general relativity (GR) is to encompass gravity and electromagnetic fields, as is often claimed, it must be formulated so as to cover travelling waves. It cannot depict them as sources of energy-mass that distort the geometry of space.

There has been progress in reformulating GR, in identifying a real energy-momentum tensor (not the pseudo-tensor of Einstein) which describes fields and associated waves carrying real energy through space – not across space, as in theories of photons. Defining a real tensor requires, however, the choice of a preferred metric, ie. with coordinates for real space.

Some leading physicists of the mid-20th Century (Vlad Fock, Steven Weinberg) saw it as essential to define a real energy tensor in GR, and were ready to adopt real space coordinates. They were largely ignored by the abstract theorists, including Smolin. Time now for him to acknowledge both real time and real space!

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Higgs-like particle

Such was the hype in billing the CERN results that the science teams were forced to come up with something definite. And that has persisted despite scientists soon questioning the fundamentalist claims: the Higgs boson does not relate to the neutrino, gravity or ‘dark matter’ and could be a composite particle.

Now it’s downgraded to a “a Higgs-like particle”: the recent $3million Fundamental Physics Prize was awarded for discovering “a Higgs-like particle at CERN’s Large Hadron Collider”.

But the British media continues in ignorance, encouraged by the aging Peter Higgs and the award of a New Year “honour”. An interview reprinted from El Mundo reports the Higgs particle in mystical terms:

“In 1963 Higgs predicted the existence of a force-carrying particle, part of an invisible energy field that filled the vacuum throughout the observable universe. Without the field, or something like it, we would not be here. The field clings to the smallest fundamental particles and gives them mass. The field, which switched on moments after the big bang, allowed particles to come together and form all the atoms and molecules around today.”

Peter Higgs played this up, disclosing emotion over-riding science:

What was so overwhelming really was the response of the audience at Cern. It wasn’t like a scientific seminar, it was like the end of a football match when the home team has won, and that was what was overwhelming to me, to be a part of that …

So cocky is Higgs that he ventures to defend religious beliefs, arguing in the El Mundo interview, that science and religion were not incompatible. He attacked Richard Dawkins for ‘fundamentalism’, without appreciating how closely he fits the Dawkins cap:

The true scientist, however passionately he may ‘believe’, in evolution for example, knows exactly what would change his mind: evidence! The fundamentalist knows that nothing will.”

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Gravitational collapse without black holes

The contemporary notion of black holes originates in Oppenheimer and Snyder’s 1939 article “On Continued Gravitational Contraction” (Phys. Rev. 56:455, 1939).  Later Roger Penrose (Phys. Rev. Lett. 14:57, 1965)  showed that the O&S metric gave rise to trapped surfaces, ie. regions of space from which no light rays can escape, and proved that within such surfaces black-hole formation is inevitable. But what if their metric is faulty?

Trevor Marshall’s challenging article uses differential geometry to show that a simple modification of the O&S metric, fully consistent with General Relativity, enables all radial light rays originating in the interior escape to the exterior. There is no trapped surface and no black hole; on the contrary there is a stable end state with finite density, contained within a sphere of Schwarzschild radius, contracting ever more slowly on itself over infinite time.

Such solutions may be seen as counter-intuitive if, above a certain density, “no force can countervail against gravity”.  Indeed, they require gravity to be repulsive in the extreme high regime, where its energy density is comparable to mass densities.  It therefore fits intuitively with the field interpretation of gravity.  On the other hand, the purely geometric interpretation based on the extreme form of the ‘Equivalence Principle’ has no light-ray connectivity, so is not consistent with causality. Is that not counter-intuitive?

Trevor Marshall’s full paper is in the December issue of Astrophys. Space Sci. (2012) 342:329–332.  DOI 10.1007/s10509-012-1170-y

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