Science Seen Time One author Colin Gillespie helps you understand the physics of your world.

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Multiverses versus Universe

In the physics stratosphere a great debate is going on. Physicists say it is about the future of physics and the nature of everything.This may be true, but the issues are also personal.

The story starts (or so it seems) with multiverses. Not long poems (though those still get more Google hits), I mean multiple-universe schemes. The idea has ancient roots in mythology. Modern multiverses may be found in comic books and fiction. The reason why the story has turned serious is that many physicists for whose smarts I have high regard now embrace one or another kind of multiverse. Of this, Italian physicist Carlo Rovelli says:

Today, many scientists do not hesitate to take seriously speculations such as … multiple universes, for which there isn’t a wit of empirical evidence.

Multiverses now appear in leading scientific journals. For example, in a recent article on quantum black holes in Science, unconstrained by referee or editor Argentinian astrophysicist Juan Maldacena can in all seriousness say:

Of course, the 10-dimensional space under consideration here is not the same as the four-dimensional region of the multiverse where we live.

Though they come in many versions, most multiverses seem to me to fall broadly in three groups (Max Tegmark finds four). Some suppose distinct or distant aspects of this universe. Others imagine universes that are, as South African cosmologist George Ellis puts it, ‘completely disconnected from our spacetime’. Then there is an in-between species, of which American physicist Sean Carroll says:

In inflationary cosmology, however, these different regions can be relatively self-contained — “pocket universes,” as Alan Guth calls them. When you combine this with string theory, the emergent local laws of physics in the different pocket universes can be very different.

So choose from: far-flung regions of this universe; other universes that are ‘disconnected from our spacetime’, wherever that is; and not-quite-disconnected pocket universes. It’s an inconsequential choice because you’ll never get to check what anybody says about them; all three kinds are utterly beyond any possibility of observation.

Physics that is beyond observation? Some say that this is a contradiction.

Next: How do physicists think themselves into such strange confabulations?

 

Justice Society of America #20 by Geoff Johns, Alex Ross, Jerry Ordway, and Dale Eaglesham

Sources

Carlo Rovelli (2009), “Unfinished Revolution”, in Approaches to Quantum Gravity, Daniel Oriti (ed.), New York: Cambridge University Press, p. 4; http://arxiv.org/pdf/gr-qc/0604045.pdf

Sean Carroll (2011), “Are Many Worlds and the Multiverse the Same Idea?”, Discover Magazine, Waukesha WI: Kalmbach Publishing, blog post May 26, http://blogs.discovermagazine.com/cosmicvariance/2011/05/26/are-many-worlds-and-the-multiverse-the-same-idea/

Juan Maldacena (2014), “Testing gauge/gravity duality on a quantum black hole”, Science, Washington: AAAS, vol. 344, p. 806; http://www.sciencemag.org/content/344/6186/806.full.pdf

Image: Justice Society of America #20 by Geoff Johns, Alex Ross, Jerry Ordway, and Dale Eaglesham

Other reading:

Max Tegmark (undated), “Welcome to My Crazy Universe”, http://space.mit.edu/home/tegmark/crazy.html

 

 

3 Comments

  1. http://siteseeker.top/heatsinkusa.com April 25, 2016 at 10:30 am #

    It’s great to find an expert who can explain things so well

  2. Aden March 5, 2016 at 12:53 am #

    Hi Bee:The asymmetry is false.Presently, we netehir individually nor collectively can ever have observed all of the past, all of the present let alone the future. The number of observations thus far made must always be smaller than the total number of possible’ observations. It follows that there consequently is no way to use axiomatically-based deductive reasoning to justify absolute belief in any fact’. With inductive reasoning, we try to approach a complete definition of an object, class or process, by extrapolation or interpolation from observation of only a sample of its parts. But it’s not logically possible to guarantee that such a definition, that depends upon contingent sets of observations, will also be true for any so far unobserved parts. This unavoidable logical incompleteness of all empirical inductive reasoning therefore must be an inescapable source of residual uncertainty and skepticism.This might be viewed as a Humean Uncertainty Principle that tells us that plausible scientific (or any other kinds of) predictions can never be proven to be absolutely true/certain or absolutely false.Therefore, in science, when any model/theory is stated in absolute terms; e.g., all swans are white ; all ravens are black ; these should be unallowable’ formulations. It is only such formulations that automatically insure the kind of trivial falsification that Karl Popper incorrectly claimed is so important in science!

  3. Darryl Nightingale August 4, 2014 at 9:38 am #

    Many modern theories of fundamental physics predict that our universe is contained inside a bubble. In addition to our bubble, this `multiverse’ will contain others, each of which can be thought of as containing a universe. In the other ‘pocket universes’ the fundamental constants, and even the basic laws of nature, might be different. Until now, nobody had been able to find a way to efficiently search for signs of bubble universe collisions . . .A team of cosmologists based at University College London (UCL), Imperial College London and the Perimeter Institute for Theoretical Physics has now tackled this problem.
    Science Daily (Aug. 3, 2011) Is Our Universe Inside a Bubble? First Observational Test of the ‘Multiverse’
    http://www.sciencedaily.com/releases/2011/08/110803102844.htm

    We can think of the original universe as a collection of bubbles and we live in one of the bubbles.
    Dept. of Physics, Syracuse (retrieved Aug. 2012) Beyond the Big Bang http://www.phy.syr.edu/courses/CCD_NEW/seti/topics/cosmology/cosmology2/beyond_Big_Bang.html

    String theory predicts that most of the universe is very rapidly expanding. However, these expanding phases are not stable, and can decay via the nucleation of bubbles of lower vacuum energy. Since our local region of the universe is not very rapidly expanding, string theory predicts we are inside such a bubble. The spatial curvature of the “universe” inside the bubbles that form by this process is negative, a testable prediction. Moreover, other bubbles will eventually form in the parent vacuum outside the bubble and collide with it. These collisions lead to potentially observable imprints on cosmology.
    Wikipedia (retrieved Aug 2012) String Theory
    http://en.wikipedia.org/wiki/String_theory

    With his outward breath Vishnu scattered clouds of bubbles into the waters, and every time he breathed in they were sucked back inside him. Each of these bubbles, which seemed so small in comparison with his gigantic sleeping form, grew into an entire universe like ours, whose lifespan was equal to a single breath of Vishnu. All these universes were clustered around the form of Vishnu like foam in the ocean.
    Ranchor Prime (retrieved Aug 2011) Hinduism and Ecology
    http://www.fov.org.uk/hinduism/hinduism.html

    Universes arise in the infinite consciousness, like bubbles on the surface of the ocean.
    Yoga Vasistha (circa 11th – 14th century AD) trans. Swami Venkatesananda (1921-1982)
    http://www.venkatesaya.com/242_vasistha02_months_tags/index.vasistha02_months_tags.php?m=5&d=25

    Like bubbles in the water, the worlds rise, exist and dissolve in the Supreme Self, which is the material cause and the prop of everything.
    Atma Bodha (A Treatise on Self Knowledge) by Sankaracharya (788-820 CE), trans Swami Chinmayananda (1916-1993)
    http://www.swamij.com/shankara-atma-bodha.htm

    The ocean waves, foams and bubbles are one and yet diverse in the universe. Similarly, are the Brahman and the world.
    Brahma Sutras (c. 200 BCE to 400 CE) trans. Swami Sivananda (1887-1963)
    http://www.swami-krishnananda.org/bs_2/bs_2.1.05.html

    In the Causal Ocean there are innumerable Brahmās rising and disappearing like bubbles. Brahmā and his creation are all part of the material universe, and therefore they are in constant flux.
    Bhagavad-Gītā (c. 500-400 BCE) trans. A. C. Bhaktivedanta Swami Prabhupāda (1896-1977)
    http://vedabase.net/bg/8/17/en

    The inexhaustible river of being flows on eternally while bubbles of creation rise on the surface, live for a time, then burst.
    Kena Upanisad (c. 700 BCE) trans. Swami Paramananda (1884–1940)
    http://www.yoga-age.com/upanishads/kena.html

    Within the framework of established knowledge of physics and cosmology, our universe could be one of many in a super-universe or multiverse. Linde (1990, 1994) has proposed that a background space-time “foam” empty of matter and radiation will experience local quantum fluctuations in curvature, forming many bubbles of false vacuum that individually inflate into mini-universes with random characteristics. Each universe within the multiverse can have a different set of constants and physical laws. Some might have life of a form different from ours; others might have no life at all or something even more complex or so different that we cannot even imagine it.
    Victor John Stenger (b. Jan 29, 1935), American particle physicist, outspoken atheist and popular religious skeptic.
    Wikipedia (retrieved Aug. 2012) Eternal inflation
    http://en.wikipedia.org/wiki/Eternal_inflation
    .

    This comment was originally posted on my Facebook page, Scientism, Intellectualization, and Cognitive Dissonance
    http://www.facebook.com/ScientismCriticizingOthersAndCognitiveDissonance
    .

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