Arguments for multiverse mutually exclusive?

Some of us have long wondered when it would become more generally apparent that most "multiverse" stuff is really just playing games around theories. Maybe now?

In Nature (19 January 2011), "George Ellis reminds us that Brian Greene's beguiling book on parallel worlds is more theory than fact.

The book is The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos (Allen Lane: 2011), and Ellis comments,

... Greene's nine types of multiverse are as follows. First, if space extends forever, an infinite number of domains similar to ours might lie beyond the part of the Universe that we can see. Second, some versions of inflationary theory — the idea that the newborn Universe had a fleeting period of super-fast accelerating expansion — predict the existence of innumerable other universes, with different characteristics from our own. Third, string theory, the pre-eminent theory of quantum gravity, suggests that our Universe might be one of many four-dimensional 'braneworlds' floating in a higher-dimensional space-time.

This option is developed further in the fourth and fifth proposals, which involve cyclic universes, or variations on physical parameters that are possible in the string-theory landscape. The sixth is a quantum mechanics idea that many worlds simultaneously exist as branches of the wave function of the Universe. The seventh suggests that the Universe is a holographic projection. The eighth states that we live in one of a set of artificial universes created as simulations on a super-advanced computer. The ninth argues that it is a philosophical necessity that every possible universe must be realized somewhere, in “the grandest of all multiverses”.

By presenting this plethora of theories, Greene gives the impression that the multiverse is on a sound scientific footing, but these nine arguments are mutually exclusive.

Yes but, in a multiverse, "mutually exclusive" is meaningless by definition.

Cosmology’s little wars: what’s a universe or two, or many?

Cosmic microwave background - the battleground

Some friends were talking about a recent story in Technology Review’s Physics ArXiv blog, “Astronomers Find First Evidence Of Other Universes” (12/13/2010).

The idea is that astronomers have found evidence that our cosmos was "bruised" in collisions with other universes:

Last month, Roger Penrose at the University of Oxford and Vahe Gurzadyan at Yerevan State University in Armenia announced that they had found patterns of concentric circles in the cosmic microwave background, the echo of the Big Bang.

This, they say, is exactly what you'd expect if the universe were eternally cyclical. By that, they mean that each cycle ends with a big bang that starts the next cycle. In this model, the universe is a kind of cosmic Russian Doll, with all previous universes contained within the current one.

That's an extraordinary discovery: evidence of something that occurred before the (conventional) Big Bang.

Today, another group says they've found something else in the echo of the Big Bang. These guys start with a different model of the universe called eternal inflation. In this way of thinking, the universe we see is merely a bubble in a much larger cosmos. This cosmos is filled with other bubbles, all of which are other universes where the laws of physics may be dramatically different to ours.

Tentative evidence for the latter proposition is said to have been found in the cosmic microwave background, though it might, researchers admit, be just a trick of the eye.

Indeed, for so momentous a discovery (evidence of other universes?), it attracted little attention.

Astrophysicist friend Rob Sheldon comments:

Penrose and Gurzadyan found these circles in the microwave background radiation (CMB) and attribute them to things that happened before the Big Bang (a time before time), using it to disprove inflation universe models. Well that got the inflation guys unhappy, who are, after all, the majority of cosmologists. So some young guy without a reputation to defend decides to take them on and claim that these circles are proof of inflation in a multiverse (a space beyond space), claiming instead that this disproves Penrose.

Neither Penrose's "aeons" require circles, nor multiverse "D-branes" require circles, so you're seeing a lot of post-facto theorizing here, ...

Yes, one had begun to wonder about that. The research is here.

Go here, here, and here for other responses, and here for Gurzadyan and Penrose’s response.

Multiverse: Recent studies suggest that some alternative universes "may not be so inhospitable" - assuming they exist

In "Looking for Life in the Multiverse: Universes with different physical laws might still be habitable" Scientific American Magazine (December 16, 2009) By Alejandro Jenkins and Gilad Perez make clear what is and is not accepted in science (as they understand it) and why:

The laws of physics-and in particular the constants of nature that enter into those laws, such as the strengths of the fundamental forces-might therefore seem finely tuned to make our existence possible. Short of invoking a supernatural explanation, which would be by definition outside the scope of science, a number of physicists and cosmologists began in the1970s to try solving the puzzle by hypothesizing that our universe is just one of many existing universes, each with its own laws. According to this"anthropic" reasoning, we might just occupy the rare universe where the right conditions happen to have come together to make life possible. Amazingly, the prevailing theory in modern cosmology, which emerged in the1980s, suggests that such "parallel universes" may really exist-in fact, that a multitude of universes would incessantly pop out of a primordial vacuum the way ours did in the big bang. Our universe would be but one of many pocket universes within a wider expanse called the multiverse. In the overwhelming majority of those universes, the laws of physics might not allow the formation of matter as we know it or of galaxies, stars, planets and life. But given the sheer number of possibilities, nature would have had a good chance to get the "right" set of laws at least once. Our recent studies, however, suggest that some of these other universes-assuming they exist-may not be so inhospitable after all. Remarkably, we have found examples of alternative values of the fundamental constants, and thus of alternative sets of physical laws, that might still lead to very interesting worlds and perhaps to life. The basic idea is to change one aspect of the laws of nature and then make compensatory changes to other aspects.

Our work did not address the most serious fine-tuning problem in theoretical physics: the smallness of the "cosmological constant," thanks to which our universe neither recollapsed into nothingness a fraction of a second after the big bang, nor was ripped part by an exponentially accelerating expansion. Nevertheless, the examples of alternative, potentially habitable universes raise interesting questions and motivate further research into how unique our own universe might be.

Well, the supernatural may be "outside the scope of science," but universes whose existence is not demonstrated, which are imagined principally to get out of a jam with the evidence from this universe, are reasonably doubted, despite thought experiments. The tentative tone here is well justified. It should be used more often.

See other multiverse and fine tuning stories:

Multiverse:

Cosmology: If you needn't worry about paying the rent Friday, you can worry about this stuff

Cosmology: Science's leader in things that don't make sense

Cosmology: Crisis of the month: gravitation

Cosmology: Multiverse - getting comfortable with a zillion of everything that is unique.

Cosmology: I seem to have yanked particle physicist Lawrence Krauss's chain

Cosmology: Wow. It takes guts to wage warwith Stephen Hawking. He appeared in Star Trek

Cosmology: Arguments against flatness (plus exposing sloppy science writing)

Cosmology: If the universe has free will, where do I go to file a claim for damages?

Fine tuning:

New podcasts on fine tuning of the universe

Also: Gravity doesn't make sense? Hold on to that thought!

Multiverse: Getting comfortable with a zillion of everything that is unique?

Can the laws of physics evolve?

Like clouds in our coffee, all these other universes

Major media, imagining themselves sober, think there are many universes, not just double vision

The Big Bang exploded; seriously, is there room for reasonable skepticism about the Big Bang?

Could God live in an infinite sea of universes? It depends.

Will the cosmic multiverse landscape ensure the triumph of intelligent design?

Now, remind me again why we need multiverse theory in the first place?

Multiverse theory: Replacing the big fix with the sure thing?

New podcasts on fine tuning of the universe

Two interesting ones here, from the Discovery Institute:

Cosmological Fine Tuning and the Multiverse Model

On this episode of ID the Future, Casey Luskin interviews Dr. Scott Chambers, who discusses his current research and his interest in the debate over evolution, which began in college and continues through this day.

Dr. Chambers explains how the evidence for intelligent design from the fine-tuning of the universe and the fundamental constants of physics "smacks of design," and he addresses the multiverse hypothesis.

Click here to listen.

Also, Is the earth uniquely situated for scientific observation? Do we live on a privileged planet?

On this episode of ID The Future we have a short clip about the book The Privileged Planet. In the book, authors Jay Richards and Guillermo Gonzalez suggest that earth was designed for scientific discovery. They introduce a new idea that more than just being rare in the universe, the earth is ideally located for scientific observation.

Go here to listen.

Here are some other stories on the controversy over whether the universe is fine tuned or whether there are many universes:

Gravity doesn't make sense? Hold on to that thought!

Multiverse: Getting comfortable with a zillion of everything that is unique?

Can the laws of physics evolve?

Like clouds in our coffee, all these other universes

Major media, imagining themselves sober, think there are many universes, not just double vision

The Big Bang exploded; seriously, is there room for reasonable skepticism about the Big Bang?

Could God live in an infinite sea of universes? It depends.

Will the cosmic multiverse landscape ensure the triumph of intelligent design?

Now, remind me again why we need multiverse theory in the first place?

Multiverse theory: Replacing the big fix with the sure thing?

(Note: If you follow me at Twitter, you will get regular notice of new Colliding Universes posts, usually when I have posted five or so stories.)

Can the laws of physics evolve?

A friend writes to say that in "The unique universe" (PhysicsWorld.com, 2 June 2009), Toronto-based cosmologist Lee Smolin attempts to develop a different view of time that allows him the laws of physics tp evolve in time. My friend wonders, "Presumably this is an alternative way of addressing the design challenge of fine tuning?"

Here's the essay's At a Glance:

Against the timeless multiverse

- Many cosmologists today believe that we live in a timeless multiverse - a universe where ours is just one of an ensemble of universes, and where time does not exist

- The timeless multiverse, however, presents a lot of problems. Our laws of physics are no longer determinable from experiment and it is unclear what the connection is between fundamental and effective laws

- Furthermore, theories that do not posit time to be a fundamental property fail to reproduce the space-time that we are familiar with

- Many of these puzzles can be avoided if we adopt a different set of principles that postulates that there is only one universe and that time is a fundamental property of nature. This scenario also opens the way to the possibility that the laws of physics evolve in time.

Well, some people go to a lot of trouble to evade the implications of fine tuning of the universe (= design).

Here is what I wrote about Lee Smolin's work in By Design or by Chance?:

New Universes Sprout Only in Black Holes?

Cosmologist Lee Smolin is a bit more conservative than Tegmark. He speculates that new universes might erupt—but not just anywhere that a particle goes one way rather than the other. Perhaps only in the middles of cosmic black holes. The new universes are disconnected from our universe, because the laws of physics break down in black holes. That is why we don’t know about them.

Smolin believes that the eruption of new universes in black holes follows the principles of Darwinism (natural selection). He explains:

"It seemed to me that the only principle powerful enough to explain the high degree of organization of our universe—compared to a universe with the particles and forces chosen randomly—was natural selection itself. The question then became: Could there be any mechanism by which natural selection could work on the scale of the whole universe?"

In other words, natural selection (the outcome of law acting on chance), lurking in a black hole, organizes a complex universe, excruciatingly fine-tuned for life. Smolin does not claim that the black hole spouts millions of them. Alternatively, he is attracted to the idea that the universe organizes itself:

"I believe more in the general idea that there must be mechanisms of self-organization involved in the selection of the parameters of the laws of nature than I do in this particular mechanism, which is only the first one I was able to invent. "

All these universes popping up in the clouds in our coffee, in the torment of a black hole, in the futility of an escaped balloon—their existence guarantees that our universe is a product of chance. If only they would exist . . . if only they would exist . . . (pp. 34-35)

Here are some more fine tuning stories:

Astronomer vs. pop science TV

Materialism strikes back: We create the universe, not God

The universe has hallmarks of desgn: And what can anyone do about it?

Like clouds in our coffee, all these other universes

Major media, imagining themselves sober, think there are many universes, not just double vision

The Big Bang exploded; seriously, is there room for reasonable skepticism about the Big Bang?

Could God live in an infinite sea of universes? It depends.

Will the cosmic multiverse landscape ensure the triumph of intelligent design?

Now, remind me again why we need multiverse theory in the first place?

Multiverse theory: Replacing the big fix with the sure thing?

Multiverse: Comic vid mocks the paradoxes

If you have decided that a multiverse makes more sense than a designed universe, chances are, you will rethink after you see this:



"Time Travelling the Universe," produced by Rob Bryanton of What You Ought to Know.

See also:

Science fiction scores big - on the reference shelf?

Science fiction: Reflections on the nature of time

Physicist to pop science writer: In a hole? Stop digging

Materialism strikes back: We create the universe, not God?

Not just aliens: The multiverse gotta be out there too!

No escape from philosophy through equations?

Now, remind me again why we need this multiverse theory in the first place ...

Letter: Multiverses are nonsense but so is much contemporary physics

The universe has the hallmarks of design and what can anyone do about it?

Quantum mechanics and popular culture: Artist's lot offers chance to produce trillions of universes

No escape from philosophy through equations?

Big physics could end up putting physicists out of a job?

Will it be a disaster for physics if the Higgs boson is the ONLY thing the Large Hadron Collider finds?

And so forth (Other stuff I have written on the bleeping multiverse, for which It, (Inc.) is suing me ... But the writ was sent to an infinite number of wrong universes, so ... )

More "who takes this multiverse stuff seriously?" stories here:

Cosmology: If you needn't worry about paying the rent Friday, you can worry aboutthis stuff

Cosmology: Science's leader in things that don't make sense

Cosmology: Crisis of the month: gravitation

Cosmology: Multiverse - getting comfortable with a zillion of everything that is unique.

Cosmology: I seem to have yanked particle physicist Lawrence Krauss's chain

Cosmology: Wow. It takes guts to wage warwith Stephen Hawking. He appeared in Star Trek

Cosmology: Arguments against flatness (plus exposing sloppy science writing)

Cosmology: If the universe has free will, where do I go to file a claim for damages?