After death, Hawking cuts 'multiverse' theory down to size

May 6, 2018 by Mariette Le Roux And Laurence Coustal
In his last contribution to cosmology, Hawking proposes dramatically scaling down the multiverse concept, a theory that has long divided theoretical physicists

With a science paper published after his death, Stephen Hawking has revived debate on a deeply divisive question for cosmologists: Is our Universe just one of many in an infinite, ever-expanding "multiverse"?

According to one school of thought, the cosmos started expanding exponentially after the Big Bang.

In most parts, this expansion or "inflation" continues eternally, except for a few pockets where it stops.

These pockets are where universes like ours are formed—multitudes of them that are often likened to "bubbles" in an ever-expanding ocean dubbed the .

Many scientists don't like the idea, including Hawking, who said in an interview last year: "I have never been a fan of the multiverse."

If we do live in an ever-inflating multiverse, it would mean the laws of physics and chemistry can differ from one to another, a concept that scientists struggle to accept.

In his last contribution to cosmology, Hawking—with co-author Thomas Hertog from the KU Leuven university in Belgium—does not dismiss the multiverse concept, but proposes dramatically scaling it down.

"We are not down to a single, unique universe," the University of Cambridge quoted Hawking as saying of the paper submitted before his death on March 14 and published this week in the Journal of High Energy Physics.

However, "our findings imply a significant reduction of the multiverse, to a much smaller range of possible universes."

While the multiverse theory has its defenders, others consider it a "fringe idea" that complicates our understanding of the universe

The new hypothesis relies on a branch of theoretical physics known as string theory, and concludes that the cosmos is "clearly finite", Hertog told AFP, though still composed of numerous universes.

'Fringe idea'

"It is a debate that touches on the very foundations of cosmology," Hertog said.

"The underlying question is whether we can achieve a deeper understanding of where the laws of nature come from, and whether they are unique."

Not everyone likes the new theory.

"The idea that we live in a 'multiverse' is a fringe idea in a small part of a subfield of the physics community," said theoretical physicist Sabine Hossenfelder of the Frankfurt Institute for Advanced Studies.

"Nobody who does serious science works with the multiverse because it's utterly useless," she told AFP.

The main problem, Hossenfelder explains, is that any multiverse theory is "underdetermined" and "doesn't contain enough information to make calculations".

For detractors, a multiverse theory complicates our understanding of our own Universe.

Thomas Hertog, who co-authored work on the multiverse concept with Hawking, says the measurement of gravitational waves can help determine whether the theory is scientifically sound

But it has its defenders too.

For astrophysicist Aurelien Barrau of Laboratory of Subatomic Physics and Cosmology in Paris, "the concept makes sense."

"It is remarkable that today numerous types of universe can be envisaged. Several theories, reliable for some and speculative for others, lead to the prediction of a multiverse," he said.

For Hertog, the new theory is a step in the right direction.

It "makes the cosmology based on our new theory a lot more predictive, a lot... stronger as a scientific theory and therefore ultimately, we hope, testable", he explains on the UK Leuven website.

'Assumptions'

Hossenfelder disagrees. She described the new theory as just another "variant" of eternal inflation, "with some additional assumptions on top of it."

Thomas Hertog, who co-authored work on the multiverse concept with Hawking, says the measurement of gravitational waves can help determine whether the is scientifically soundHertog hopes to use gravitational waves, ripples in the fabric of spacetime caused by black hole collisions, supernova explosions, or the formation of the early Universe, to test the new hypothesis he created with Hawking.

The British cosmologist died at the age of 76 after a lifelong battle against , which paralysed him and left him unable to speak.

Hawking, who once said his life goal was "a complete understanding of the universe", famously overturned a core tenet of physics by predicting that black holes—believed until then to devour everything in their vicinity, including light—leak radiation.

Explore further: Taming the multiverse—Stephen Hawking's final theory about the big bang

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RobertKarlStonjek
1 / 5 (7) May 06, 2018
String theory, religion and multiverse each rely on faith in the inspired seer rather than empirically verifiable science.

Each of them, including the Christian religion, hope that one day physical verification of their faith will occur.

Do we really need this in science?
mackita
1 / 5 (4) May 06, 2018
In dense aether model the Universe is infinitely dimensional and large, there is no place for some multiverse. But the observable portion of Universe exhibits some patterns of multiverses in the sense, that distribution of extradimensions inside our 4D space-time isn't homogeneous (their projection into 4D isn't compact manifold). Which is most clearly visible on massive bodies and particles - they're all pretty separated each other. The simplest way how to understand is is the water surface analogy of emergent space-time. At sufficient distance all ripples would get scattered into underwater sound waves, which propagate much faster than the surface ripples and portion of their energy gets returned back. Which means we would see our Universe from inside out at the boundary of its visibility scale, which may resemble effect of parallel universe, sharing its boundary with our Universe at the particle horizon. This hypothesis can be tested by hall of mirror effect for example.
mackita
1 / 5 (2) May 06, 2018
Another insight comes from the fact, that every space-time curvature around massive objects behaves like embedded lobe of particle horizon (surface of observable universe) and it also brings extradimensional phenomena to its surface. As you may guess, these phenomena are colloquially named dark matter, whereas the extradimensions (violations of relativistic FRLW metric) at the perimeter of particle horizon are recognized as a dark energy, Gurzadyan-Penrose circles, WMAP cold spot, CMB anisotropy, dark axis and dark flow. They're not manifestation of some multiverse - rather manifestation of intrinsic inhomogeneity of both our space-time both extradimensional curvatures projected into it.
Benni
1 / 5 (10) May 06, 2018
Cosmology is a great fantasy.

You can have anything you want & you never need to know how to solve differential equations to be tagged as someone who has a scientific mind bent, right jonesy? schneibo? Etc?
rodkeh
1.5 / 5 (8) May 06, 2018
More meaningless nonsense from an irrelevant sideshow cripple!
Steve 200mph Cruiz
4.5 / 5 (6) May 06, 2018
I think this is actually pretty important.
Yeah most theories of a multiverse aren't scientific, but there are a lot of lines of reasoning that imply it could be a possibility. By discovering constraints on the allowable physics of hypothetical other universes, maybe we will eventually get some insight into our own measurable universe, and why it is the way it is.

Who knows what gravitational astronomy is going to bring to the table over the next 30 years, we've only scratched the surface of what we can measure the cosmos with. This branch of science has only been around for 100 years, who knows where we will be at 400 years from now.
granville583762
3 / 5 (2) May 06, 2018
What happened to gravitons antiparticle?
Steve 200mph Cruiz > Who knows what gravitational astronomy is going to bring to the table over the next 30 years, we've only scratched the surface of what we can measure the cosmos with. This branch of science has only been around for 100 years, who knows where we will be at 400 years from now.

We've been using Chinese rockets for a 1000years, in 400yeays that will be 1400years and its already 50years since we last stepped foot on a planet, and that was in earth's orbit.
What has happened to theorising of late, what happened to gravitons antiparticle, the gravitons antiparticle will free us of those obsolete chemical rockets that have served their purpose?
mackita
1 / 5 (2) May 06, 2018
"Nobody who does serious science works with the multiverse because it's utterly useless said theoretical physicist Sabine Hossenfelder"
It's cultural thing as Dr. Hossenfelder does research of quantum gravity phenomenology. Many string theorists refrained to multiverse speculations when their own deductions failed experimental tests at LHC and elsewhere. The resistance against multiverse concept is particularly strong between proponents of competitive (loop) quantum gravity (theory), because they consider it as a re-incarnation of stringy theories. Their hostility was inspiration for relations of Sheldon and Leslie Winkle in famous Big Bang Theory sitcom. There were rumors, that Dr. Hossenfelder served as an inspiration for Leslie character personally, because she's a bit similar to her...
mackita
1 / 5 (2) May 06, 2018
If I would utilize the dense aether model, I wouldn't be completely dismissive regarding multiverse, because the Universe looks like very lose and fuzzy cluster of bubbles, with the largest one centered to observable part of Universe and smaller ones embedded both inside both outside of it (with increasing fuzziness and randomness). The difference is, this perspective is virtual, generated by scattering of light at the quantum fluctuations and it would travel together with us whenever we would move across Universe: new bubbles would emerge before us and these ones behind our back would dissapear. The traces of this dodecahedron geometry can be observed in CMB fluctuations, but it's also heavily broken and partially replaced by spherical harmonics across half of sky. This is because at largest scales the particle and wave characters of Universe become indistinguishable.
mackita
1 / 5 (1) May 06, 2018
This situation can be also understood/imagined by 2D water surface model, because surface ripples form solitons, which behave like particles and they would occupy the most compact hexagonal packing there (the dodecahedral foam structure in 3D). But at such large distance most of surface ripples would get also scattered into underwater waves, which would resonate in circular/spherical harmonics in 2D/3D. The resulting observable structure therefore must be composite of both - and this is really what we can observe in angular power spectrum of CMB. The labeled points just correspond the dodecahedral vortices of E8 geometry in it.

In addition, the Universe is deformed into saddle shape by CMB anisotropy at large scales, so that one part of sky looks like system of densely packed particles, whereas the rest rather like system of standing waves. It's just simple, right?
mackita
1 / 5 (1) May 06, 2018
Just this fuzziness of the dark matter/CMB geometry at large scales represents an obstacle for deterministic models of contemporary physics, because the Universe looks like strange mixture of many alternative models at large scales and the theorists have nowhere to catch there.
We can formulate it like this: just imagine, we are compressing dense gas up to level, when the solitons / wave packets between its density fluctuations will form another density fluctuations recursively. Suppose for example we compress particles at the core of black hole up to level, when they all will be just about to dissolve into homogeneous continuum. Both particle packing both wave packing will apply in the same way in the resulting mixture. Which largest periodic geometry we could observe in this nearly random mess? Well, this is just what we can see in nearly homogeneous and transparent space on the sky: space-time looks like transparent interior of black hole
mackita
1 / 5 (1) May 06, 2018
Most of string theory is just about geometry of most compact particle packing within hyperspace, despite the string theorists realize it or not. Or better to say, the physicists aren't sure which geometry is the best one, but important group of string theories deals with exceptional Lie groups in eight-dimensional space. This so-called E8 group just describes most compact packing of 8-dimensional hyperspheres residing on kissing (touching) points of another hyperspheres recursively into complex nested polyhedral (mostly dodecahedral) structure. The answer, why just this structure describes most compact particle packing follows from quantum mechanics: at high energies the virtual photons exchanging energy between squeezed particles behave like massive particles by itself and as such they must be also involved in packing geometry, as they also occupy some space.
mackita
1 / 5 (1) May 06, 2018
Now, when we compress particles in the lab, for example some gas inside the sealed capillary, we can see, that the condensation of gas into fluid doesn't run completely homogeneously: the phase interface forms layers which repeatedly dissolve and form - about three times in total.. This peculiar phenomenon is caused by the fact, that just 3D structures have smallest surface/volume ratio, they're most compact ones. Even multidimensional hyperspace therefore will be composed on nested layers of foam, embedded inside another ones - three layers in total. These layers give origin of three particle generations between others. Original Howking-Hartle model handled Universe like quantum particle and it proposed, that our Universe would be also surrounded of two or three adjacent layers of parallel Universes. In his last study Hawking apparently changed his mind and reduced it into single one.
mackita
1 / 5 (1) May 06, 2018
IMO this step is rather logical, because even if some multiple layers of parallel Universes would exist outside our Universe, they wouldn't be visible for us anyway in similar way, like the objects hidden inside the fog - behind the particle horizon of Universe. But the less are parallel Universes are visible outside of Universe, the more their traces are visible inside of it in form of dark matter filaments and clouds between/around galaxies where they also form structure of nested foam. Therefore the unconstrained Howking-Hartle model still lives - just inside of our Universe, not outside it.
Steve 200mph Cruiz
5 / 5 (6) May 06, 2018
What happened to gravitons antiparticle?


Bosons dont have anti-particles, there is no such thing as an anti-photon either.

I understand rocket tech is old, I just don't think the science of cosmology existed until Hubble found out we aren't the only galaxy and that the universe appears to be expanding faster and faster. For it to be a science you need to take measurements of the large scale structure of the universe, which we don't have until about 100 years ago.
Rocketry is a different subject
granville583762
5 / 5 (1) May 06, 2018
What happened to gravitons antiparticle?

Steve 200mph Cruiz > Bosons don't have anti-particles, there is no such thing as an anti-photon either.
I understand rocket tech is old, I just don't think the science of cosmology existed until Hubble found out we aren't the only galaxy and that the universe appears to be expanding faster and faster. For it to be a science you need to take measurements of the large scale structure of the universe, which we don't have until about 100 years ago. Rocketry is a different subject

Its different but related, there is a limit as to what we can theorise about our universe that can only be corrected by visiting our galaxies, at present we have no space propulsion engine so no means of getting there, as our moon is the limit and now gravitons antiparticle is ruled out. Theorising beyond our solar system comes with the wish to visit; we cannot even send unmanned space vehicles beyond our solar system in our lifetime.
BobSage
1.4 / 5 (9) May 06, 2018
If the material universe is all that exists,
Then spirit cannot exist.
But you are spirit.
Therefore, the material universe is not all that exists.

Isn't it clear that physics and cosmology and even biology are leading to the conclusion that that the universe is not material?

The material paradigm is good for inventing things. It goes beyond its capabilities when it attempts to explain creation.

Varade
1 / 5 (1) May 07, 2018
Heisenberg uncertainty is the proof that our universe/multiuniverse is finite.
granville583762
5 / 5 (1) May 07, 2018
Excessive theorising has clouded the distinction between science and theology
BobSage> If the material universe is all that exists,
Then spirit cannot exist.
But you are spirit.
Therefore, the material universe is not all that exists.
Isn't it clear that physics and cosmology and even biology are leading to the conclusion that that the universe is not material?
The material paradigm is good for inventing things. It goes beyond its capabilities when it attempts to explain creation

Spot on BobSage, you have homed in on the precise point as to what is troubling science of late. Excessive theorising has clouded the distinction between science and theology, Heisenberg uncertainty has now been brought into the theological bandwagon stating our universe is finite
mackita
1 / 5 (1) May 07, 2018
Our understanding of the universe's expansion is really wrong.. Mine not.. :-) The article is paywalled but it addresses this problem. You can also consider it as a manifestation of multiverse (umm, multiple results for the same effect) - but I'd recommend to understand dense aether model first..
Urgelt
4 / 5 (4) May 07, 2018
Self-styled sage 'Bob' wrote: "But you are spirit. Therefore..."

Self-styled sage Bob does not understand the difference between an assumption and a fact.

He's none too clear with definitions, either. What, exactly, does he mean by 'spirit' in the context of a discussion about science?

Science is about measurements. Where are Bob's measurements?
mackita
1 / 5 (1) May 07, 2018
You can find similar text at many other places. We would observe similar effect even at the water surface, because the speed in which waves are scattered depends on their wavelength and the longer waves scatter more. BTW The same effect should be observable at the extreme small distance scale and it leads to artifact called Higgs doublet.
milnik
1 / 5 (2) May 07, 2018
Who allows the function of each of your living cells and you know which programs you have built into your brain. ? Where can these programs be purchased and what they need to function? Imagine how small a sperm is and what develops from it. Whether it was created under the influence of a "small, inch, medium, virtual burst". Every normal person, if he knows himself, will never say that everything was created out of nothing, and that nothing spreads, and multiplies it as viruses.
Call upon consciousness to return to you, because you will disappear in some universe, which some see as a bubble. These are your theories of Dante's hell. When you enter there, do you see a warning: "through me I enter the eternal city of distress, through me passes into eternal suffering, leave all who enter."
granville583762
3.7 / 5 (3) May 07, 2018
Steven Hawkins suggestion that Georges Lemaitre Cosmic-Egg is billions in number

Everyone has heard of Georges Lemaitre's Cosmic-Egg where it has the escape velocity of light, in effect we are living in a blackhole with a 15billion light radius. All a multiverse is are Cosmic-Eggs spread throughout the vacuum of space. There are no intellectual gymnastics hoops of the imagination to jump through to realise the blackhole with its 15billion light radius that we inhabit is the same as Georges Lemaitre's Cosmic-Egg but in billion of numbers.
Just like when the sun when round the earth and we realised our arrogance and believe differently.
It is equally arrogant to refute Steven Hawkins's suggestion that Georges Lemaitre's Cosmic-Egg is billions in number!
Porgie
1 / 5 (3) May 07, 2018
What ever he believed or though he believed he has now solved the great mystery. And will satisfy his debt if there is one. Of course he is answering to a higher power as I believe. He was an arrogant fool.
milnik
1 / 5 (2) May 08, 2018
Is it logical and logical to make conclusions and claims about phenomena in the universe at distances of billions of light years, and no one has yet learned from science: why our moon, which is only one light-time from us, no one knows what our moon always has one side facing the earth?
Do you know who you give many of your claims about these remote femmes? If science finds out this about the moon, then it will find out what are the true and true paths of the celestial bodies and will see that Einstein's, Lorenz's and Hablov's claims are only fabrications and their fossom. Who wants to discuss the position of the moon?
RTM99999
2 / 5 (4) May 09, 2018
granville583762
"Steven Hawkins suggestion that Georges Lemaitre Cosmic-Egg is billions in number "

Urgelt
"Science is about measurements. Where are Bob's measurements?"

Sorry guys and gals according to research done by CERN and BASE the Universe shouldn't exist at all.

"All of our observations find a complete symmetry between matter and antimatter, which is why the universe should not actually exist," and "An asymmetry must exist here somewhere but we simply do not understand where the difference is. What is the source of the symmetry break?" - Christian Smorra of the RIKEN institute

milnik
1 / 5 (3) May 09, 2018
Anyone who does not know what matter is, and how and from what it forms, is only man if he is, without consciousness, and therefore does not know any of the natural laws. With such human beings everything is blurred in their memory, like some dull dream. Which fool can say that there is no universe, or there are billions of universes. Then it was formed as a forgery of nature in order to prove that there can be such, which do not comprehend anything in the universe.
mackita
1 / 5 (1) May 10, 2018
Hawking: based on this we conjecture that the exit from eternal inflation does not produce an infinite fractal-like multiverse, but is finite and reasonably smooth.

This Hawking's particular study is for example commented here. Quite ironically the outcome of this study actually disfavors multiverse concept, despite Hawking meme (personality cult actually) has been recently widely abused for promotion of it (see for example here 1, 2). But no one bothered to actually read it - even the critics, not to say supporters of multiverse... ;-)
Is this even possible?
It just illustrates, how the multiverse concept became socio-economical artifact - a hype separated from facts (i.e. the religion)
Da Schneib
3 / 5 (4) May 10, 2018
Who the hell is Steven Hawkins?
milnik
not rated yet May 11, 2018
Hawking,
like most scholars, are pupils who were educated in "elementary school Einstein" and had their deity BB, to which they still believe today.
granville583762
not rated yet May 11, 2018
Da Schneib> Who the hell is Steven Hawkins?

Its a bit late now, he's with the angels in eternal peace.
mackita
not rated yet May 11, 2018
granville583762
5 / 5 (2) May 11, 2018
Atheists and their eternal peace
It's a bit late now, he's with the angels in eternal peace

mackita> Angels you say?

Even atheists have their seat reserved, it is metaphysical figure of speech because there is nowhere to go as in the end we just go back to the earth whence we came.

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