New star described in a model combining relativity and quantum mechanics

March 9, 2018, International School of Advanced Studies (SISSA)
Credit: CC0 Public Domain

A new kind of star is reported in a study by SISSA postdoctoral researcher Raúl Carballo-Rubio. In a paper recently published in Physical Review Letters, Carballo-Rubio describes a novel mathematical model combining general relativity with the repulsive effect of quantum vacuum polarization. The result is a description of an ultra-compact configuration of stars that scientists previously believed did not exist in equilibrium.

"As a consequence of the attractive and repulsive forces at play, a massive star can either become a neutron star, or turn into a black hole" says Carballo-Rubio. In neutron stars, stellar is the result of the balance between gravity, an attractive force, and a quantum mechanical repulsive force called degeneracy pressure. "But if the star's mass becomes higher than a certain threshold, about three times the solar mass, the equilibrium would be broken and the star collapses due to the overwhelming pull of the gravitational force."

In the study, Carballo-Rubio investigated the possibility that additional quantum mechanical forces expected to be present in nature permit new equilibrium configurations for stars above this threshold. The additional force is a manifestation of the quantum vacuum polarization effect, which is a robust consequence of mixing gravity and mechanics in a semiclassical framework. "The novelty in this analysis is that, for the first time, all these ingredients have been assembled in a fully consistent model. Moreover, it has been shown that there exist new stellar configurations, and that these can be described in a surprisingly simple manner."

There are still several important issues that remain to be studied, including the observational applications of these results. "It is not clear yet whether these configurations can be dynamically realized in astrophysical scenarios, or how long would they last if this is the case." From an observational perspective, these "semiclassical relativistic stars" would be very similar to . However, even minute differences would be perceptible in the next generation of gravitational wave observatories: "If there are very dense and ultracompact in the Universe, similar to black holes but with no horizons, it should be possible to detect them in the next decades."

Explore further: A better way to model stellar explosions

More information: Raúl Carballo-Rubio, Stellar Equilibrium in Semiclassical Gravity, Physical Review Letters (2018). DOI: 10.1103/PhysRevLett.120.061102

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cantdrive85
2.4 / 5 (5) Mar 11, 2018
Nevermind the fact that relativity and QM are incompatible.
poisonoak
2 / 5 (4) Mar 11, 2018
Increasing disturbing trend at phys.org and other web sites - tacking on a picture, any picture, that has nothing to do with the subject at hand. See https://phys.org/...em.html. Same stupid picture having nothing to do with the article.
mackita
1 / 5 (2) Mar 11, 2018
Same stupid picture having nothing to do with the article
This is picture of dense aether model, so-called AWT.
quantum vacuum polarization effect, which is a robust consequence of mixing gravity and quantum mechanics in a semiclassical framework
Quantum vacuum polarization effect is product of Coulomb electromagnetic forces, not gravity. Charged stars will be really stabilized against their collapse, but the application of quantum polarization to gravity is merely conformal bootstrap approach.
Turgent
1 / 5 (1) Mar 11, 2018
Increasing disturbing trend at phys.org and other web sites - tacking on a picture, any picture, that has nothing to do with the subject at hand.


Yes. Some are very misleading and detrimentally so.
mackita
1 / 5 (2) Mar 11, 2018
The additional force is a manifestation of the quantum vacuum polarization effect, which is a robust consequence of mixing gravity and quantum mechanics in a semiclassical framework.
Vacuum polarization effect is also basis of many "field based" dark matter theories (MOND, MiHSc) so that we could also say, that "quantum-like repulsive" dark matter effects stabilize dense stars before their collapse. Ironically similar hyper-dimensional effects stabilize black holes before their quantum evaporation once they get finally formed, so that dark matter will change into attractive force beneath the event horizon (due to topological space-time inversion existing there) and it introduces hysteresis or sorta "quantization" into normal matter - black holes transitions.
mackita
1 / 5 (2) Mar 11, 2018
Within human society we can also observe dark matter-like effects at the boundary of high informational density like "repulsively" dismissive attitude of mainstream community (black hole) toward changes of established paradigm from outside (typically aether) followed by unhealthy adherence to ideas which would support it coming from inside (string theory) - despite that both concepts converge to similar outcome and predictions - they're just perceived from opposite sides of informational singularity or event horizon.
The analogy of quantum polarization effect is so-called pluralistic ignorance, i.e. subtle and hardly confessed yet omnipresently biased attitude of every peer of mainstream community against/toward ideas coming from outside/inside of mainstream. Without this attitude the mainstream paradigm would already collapse into a narrow singularity of hard-core sympathizers - but pluralistic ignorance keeps it alive.
mackita
1 / 5 (2) Mar 11, 2018
Note also how dense aether model illustrates the topological inversion of space-time at the event horizon: the total amount of observable information remains preserved for any observer passing it, it's just based on a new - usually dual - space-time metric. The similar effect happens during paradigm change in science: many connections of old paradigm get forgotten (who actually today remembers the algebra of defferents and epicycles of geocentric model?) but many new connections are rederived from exactly the opposite model (heliocentric one). From position of us, distant winners the transition to heliocentric model may look like scientific revolution - but in reality it took more than two centuries before the heliocentric model has been finally accepted. The similar thing happens with event horizon of black holes, which looks like sharp reflecting boundary from distance but from proximity it wouldn't differ very much from universe around us.
mackita
1 / 5 (2) Mar 11, 2018
From an observational perspective, these "semiclassical relativistic stars" would be very similar to black holes. However, even minute differences would be perceptible in the next generation of gravitational wave observatories
Such a semiclassical black holes can be detected way easier as they would be based on merely classical objects (ultradense quark and neutrino stars) surrounded by event horizon, which may or may not exist above physical surface of such "star". Once the star will become "naked singularity" (usually at poles for fast rotating and/or charged object), it will change into a brightly radiating object ("white hole"). As you may guess, many black hole jets would belong into this category, once it will turn out, no accretion of matter from outside is actually needed for their formation.
Da Schneib
2.3 / 5 (3) Mar 12, 2018
One of the things not to lose sight of here is that this doesn't mean black holes are theoretically excluded. It just means that there are other things between BHs and neutron stars that we haven't found any demonstrable examples of; and we're not even sure they're stable solutions, so don't hold your breath until this math all gets worked out.

The paper is open access at arXiv: https://arxiv.org...06.05379
mackita
1 / 5 (1) Mar 12, 2018
this doesn't mean black holes are theoretically excluded
It depends on what you call "theoretically". By quantum mechanics itself all particles and massive objects are excluded - not just black holes. This theory predicts only repulsive forces - never attractive.
Anda
4 / 5 (4) Mar 12, 2018
Still there "aether guy"???
It's Mackita now... aren't you tired of writing the same nonsense over and over for years?
Spaced out Engineer
not rated yet Mar 12, 2018
Nevermind the fact that relativity and QM are incompatible.

Yes, relativity is wrong, but useful enough for all intensive purposes in some dimensialities, namely those of the 4th kind. A reduction whose illusion tells us there is more to time, whether we say by the collectively exhaustive or the maximally extended.

You bring the integer of dimension. I'll bring the mirroring of features. We will get by and by.
mackita
1 / 5 (2) Mar 12, 2018
aren't you tired of writing the same nonsense over and over for years
Just above in the article we can all read
in neutron stars, stellar equilibrium is the result of the balance between gravity, an attractive force, and a quantum mechanical repulsive force called degeneracy pressure
The theory which predicts different result for the same phenomena can be never reconciled at the formal level in similar way like system of equations x = -4 and x = +5 can never have any common solution. I'm of course aware that both theories are nearly equivalent consequence of insintric and extrinsic perspectives of curved space-time observation by its own waves, but this level of understanding isn't what the formally thinking mainstream physicists are looking for. They hope instead, they could construct an theory which would merge x = -4 and x = +5 equations into a single formula.

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