Why is the universe
"just right" for life?
Do we live in a multiverse
or was our universe designed?
( Part 2 )

by Craig Rusbult, Ph.D.

A History of Two Pages:  This page was written first (in 2003) and later I condensed it to form Part 1.  Since then I've been revising Part 1 more than this page;  in March 2010, I went through this page and deleted a few parts that duplicated ideas in Part 1, but there are still some parts that have a partial duplication plus some "added value" that supplements Part 1.  Basically, you should read Part 1 first, then look through this page to see what looks interesting.

      Here is a brief summary from a condensed-and-revised version of this page about Anthropic Principle, Fine Tuning, and Theology: Multiverse and/or Intelligent Design.  You should read it first to get a quick overview of "what needs explaining" plus two possible explanations:
      An amazing discovery of scientists, in recent decades, is that many properties of the universe are "just right" for life.  Most scientists are convinced that the constraints on a life-allowing universe are very tight, that small changes would make the existence of intelligent life impossible.  There are, however, two main theories claiming to explain why our universe is what it is:
      • The simplest causal theory is Intelligent Design plus design-directed action, with our universe being designed and produced by an extremely intelligent and powerful designer/producer who cleverly designed the universe so it would support life.
      • A universe able to support life is extremely improbable, but a theory proposing a Multiverse (containing Many Universes) is a way to beat these odds.  Imagine that scientists have analyzed the probability of a universe capable of producing life-forms that are intelligent, and have estimated the odds to be extremely low.  If there is only one universe, and it was not designed for life, we must conclude that we are extremely lucky.  But if, as proposed in a Multiverse Theory, there were an immense number of universes, and the properties of these universes were distributed across a wide range, the odds would favor having at least one universe with intelligent life.
      note:  Perhaps we should just say "So what?" because if we are observing a universe, it obviously must have properties that allow our existence.  This anthropic principle — which states that because humans exist, we will observe a universe consistent with our existenceis logically valid, and is compatible with either the presence or absence of a designer, so it doesn't favor either possibility.

Properties — Characteristics, Constants, and Conditions
      When thinking about "what might not happen" if the universe was slightly different, we can think about three types of properties — characteristics, constants, and conditions:
      • The basic characteristics of our universe include matter/energy in a variety of "elementary particle" forms (like protons, electrons,...) and their possible components (such as quarks & leptons), + and - charge, wave/particle duality (which prevents matter from forming inert clumps of +- charge) and the resulting quantizations, Pauli Exclusion Principle, 3-dimensional physical space, four basic forces (gravitational, electromagnetic, weak nuclear, strong nuclear), causal relationships (as formulated by Newton, Einstein, Faraday, Maxwell, and others) and more.
      • Some important features of these characteristics depend on physical constants such as the force constants that help determine the strength for each type of force, Planck's Constant for the quantization of energy, the charge and mass for each particle, and the relative mass-ratios between protons, neutrons, electrons,....
      • The current state of the universe also depends on initial conditions such as the initial spatial distribution and amounts of matter and antimatter (and the excess of matter over antimatter), and the initial rate of expansion during the Big Bang.

Should we be amazed?  If a universe could produce and support life with almost any combination of properties, we could say "Of course there is life, since wherever matter exists there will necessarily be life."  The reality, however, is that a universe able to support life is extremely improbable.
      Is carbon-based life the only possibility?  Probably.  In principle, life might exist without familiar ingredients like sunshine or DNA, but most scientists are convinced that the constraints on a life-allowing universe are very tight, that small changes would make it impossible to produce intelligent life of any kind we can imagine.  Based on scientific evidence, there is little doubt about this conclusion.

    The Science & Theology of Design:  A scientific theory of Intelligent Design, when supplemented by a theistic interpretation, can become a theological theory of divine creation.  And for those who want to avoid the need for a designer/creator, a scientific theory of Many Universes, when supplemented by an atheistic interpretation, can become a theological theory about a universe without God.  {more about science and theology}

Beating the Odds
      A theory of Many Universes (MU) proposes a way to beat the odds.  Imagine that scientists have analyzed the probability of a universe capable of producing life-forms that are intelligent (so they can analyze the probability for their own existence!) and have estimated the odds to be very low, less than 1 in a thousand million billion trillion zillion.  If there is only one universe, we must conclude that we are very lucky.  But if there were enough universes (as proposed in MU), and if all properties of these universes were distributed across a wide range, the odds would be highly in favor of having at least one universe with intelligent life.
      For example,... {most of what was here is now in the appendix of Part 1}

      Questions about a Multiverse

      How could it be produced?
If there is a multiverse (with many universes) instead of just one universe (the one we live in and can observe), how was the multiverse produced?
      Before our universe, perhaps there was a long series of sequentially existing universes produced by cycles involving a Big Bang expansion followed by a Big Crunch contraction of the whole universe into a concentrated ball of mass-energy that would cause another Bang (and Crunch) and then another, over and over until it produced our universe.  Although this theory was popular for awhile, it has been discredited for a variety of reasons (*), and most current proposals are for simultaneous universes, as explained below.  * There doesn't seem to be enough mass to cause a Big Crunch ( 1  2a  2b ) and "dark energy" causes expansion rather than contraction, so proposing that another Big Bang would follow is wildly speculative (and in fact it seems to be wrong) and if properties were different (why? more speculation is required) a universe would soon occur in which there would be no crunch, and the series would end.
      Currently, most theories about Many Universes propose a multitude of simultaneously existing universes, with a gigantic Mega-Universe containing many smaller universes, including our own.  The most popular theories propose that at the beginning of a big bang there is an inflationary period (with curved space and vacuum energy, as described in general relativity and quantum mechanics, plus a hypothetical inflaton field) in which an immense number of additional "big bang universes" are produced.  In another MU theory, new universes are born in the energy-dense environment within black holes.  A variety of speculative proposals for universe-producing mechanisms include curved space, vacuum energy, quantum tunneling, imaginary time, and backward causation, and also (or combined with) the "many worlds" interpretation of quantum mechanics.

      Would different universes have different properties?
      If all universes are formed in the same way, we might expect them to have the same properties.  If the properties are different in each universe, as proposed by MU, why are they different?  To explain the origin of many "worlds with varying properties," scientists have proposed many multiverse-mechanisms, involving string theory, inflationary expansion, quantum mechanics, black holes, and colliding 10-dimensional branes.  { one possibility }

      How plausible are theories about a multiverse?
      For many scientists, a religious motivation for proposing MU is to support an atheistic worldview by avoiding a conclusion that "our universe was designed and created by an extremely intelligent and powerful designer/creator."  And for other scientists, a religious motivation for proposing an intelligent design of the universe (ID) is to provide scientific support for a theistic worldview.  But in each case, with MU or ID, we can evaluate the scientific theory based on scientific evidence and logic, independent of any nonscientific motivations for proposing the theory.
      According to current theories in physics, even if other universes existed they could not be observed, so there is no direct empirical evidence for or against MU.  Why?  If our theories predicted that we should be able to observe other universes, and we did not observe them, this would be evidence against MU.  But if non-observation is predicted by both MU and ID, non-observation is scientifically neutral.  Similar logic applies to the current lack of empirical testability for string theory.
      Theories about MU seem untestable and are highly speculative, but (according to those who are more expert than myself in the relevant fields) MU theories are consistent with accepted theories of science, and are worthy of serious consideration.  For example, Robin Collins says that "it is in the realm of real physical plausibility that a viable inflationary many-universes scenario could be constructed that would account for the fine-tuning of the parameters of physics and the initial conditions of the cosmos," but then he explains why "there still remains a powerful case for design from physics and cosmology."  For example, "even if a 'many-universes generator' exists it seems to need to be well-designed" in order to produce a multitude of new universes with widely varying properties.  Therefore, the correct theory could be Intelligent Design AND A Multiverse."  William Lane Craig is more critical of inflationary theory, but he agrees that it does not eliminate questions about design: "Inflationary scenarios have problems of their own,... [and they] seem to require the same sort of fine-tuning which some theorists thought these models had eliminated."  {details}
      Does MU violate principles of simplicity and parsimony?  Not necessarily.  We know that one universe exists, but we cannot know with certainty that there is only one universe.  Victor Stenger, a proponent of MU and opponent of ID, explains: "Some theologians and scientists dismiss the notion as a gross violation of Occam's razor.  It is not.  No new hypothesis is needed to consider multiple universes.  In fact, it takes an added hypothesis to rule them out — a super law of nature that says only one universe can exist.  But we know of no such law, so we would violate Occam's razor to insist on only one universe."  Robin Collins, a proponent of ID, agrees: "The only way we could close this door [for MU theories] is if we discovered that the ultimate laws of physics did not allow either many-universes or enough variation in the parameters and laws of physics among universes."

      A Grand Unified Explanation?

      Some scientists hope that eventually a "grand unified theory of everything" will show why it is physically necessary for properties to be what they are in our universe.  Some atheists are hoping this would support their theory of non-design.  But this seems analogous to hoping that we will find, if we deal one hand (if the unified theory applies to all universes within the multiverse) and we see a royal flush, that the supposedly random dealing is "fixed" (but not by a designer) so it can produce only a royal flush.
      If scientists do discover/construct a grand unified theory, why would we conclude — if there is only one way to combine everything into a set of properties (if the unified theory applies to all universes within the multiverse *), and if this one set produces a universe that allows life — that the universe, operating as described in this elegantly unified theory, has not been cleverly designed?   (* Or we could rationally conclude, along with Robin Collins, that a mechanism which produces universes with widely varying unifying properties would "need to be well-designed." )
      Or instead of a unified theory saying "there is only one possibility" some variation might be possible, but (due to the structure imposed by the unifying relationships) this variation occurs only within a narrow range.  In this case the question would be modified, "If there is no design, why should this narrow range include the combination of properties needed for life?", and it would still pose a challenge for non-design.
      Although a unified theory might provide evidence against design, it seems more likely that it would support a theory of design.

      A Conclusion?
      How did our universe begin, and why does it have properties that allow life?  I think the most plausible explanation is that our universe was designed and created by a designer/creator whose intelligence and power are beyond our abilities to comprehend.  But this theory cannot be proved, and alternative theories about "many universes" also seem impossible to prove or disprove, largely because our evaluations are hindered by an absence of empirical data about what existed and what happened before the Big Bang.
      Theistic and atheistic worldviews propose different descriptions of reality (and explanations for it), including different ideas about what existed before the beginning of the universe.  An atheist assumes the existence of a materialistic capability for creating our universe.  A theist assumes the existence of God, who has this capability.  Each asks the other, "Can you explain what caused the existence of what you assume as the starting point?"  Neither offers an answer that satisfies the other, and neither assumption can be tested.  Should this lack of a conclusion bother us?  No.  In fact, I think that a state of uncertainty is the way God wants it to be.  What is the spiritual significance of this logical deadlock, with humans apparently unable to prove or disprove the existence and actions of God?  Why isn't God more obvious?


      For more information about the many ways in which our universe is "just right" for life, visit the links-page for Design of the Universe.   {back to main body}

      Is the universe designed to PRODUCE life?
      Why do I describe a universe cleverly designed "so it would support life" but not "so it would produce life"?  Because natural process does seem sufficient to support life, but I think it seems unlikely that it will produce life from lifeless matter.  There are two types of design theories, proposing design-directed action at the beginning of history (in a design of the universe) and during the history of nature, as explained in the homepage for Origins Evidence.  In the community of Christian scientists, there is agreement that the universe was designed to support life, but not about whether it was designed to produce life, or if design-action during history was necessary.   {back to main body}

      Scientific Theories and Theological Theories
      For each of the two main explanations for fine tuning (a designed universe, or a multiverse that may or may not be designed) we should distinguish between the basic scientific theory and a semi-associated theological theory that is constructed when the science is supplemented by interpretation.  The distinction between design (science) and creation (theology) is summarized in another page.   {back to main body}

      String Theory and "many worlds" Quantum Mechanics
Here is a possible mechanism (it's one of the numerous speculations) for producing many universes with varying properties:  In string theory, during the early high-energy inflationary expansion of a Big Bang the "string shapes" vary rapidly, thus producing a temporary variability in the string-shapes until they "freeze" into a stable form (before the inflationary period ends) and produce the stable properties of nature in a particular universe.   { But even if string theory is true, some properties would not be controlled by string-shapes, as explained in the section below. }  Or there might be other mechanisms, either currently speculated or now unknown, that would produce variability.  {string theory: superstringtheory.com & superstrings! & caltech.edu}
      And in a "many worlds" interpretation of quantum mechanics, every quantum interaction — including those that would occur during the inflationary period when property-determining string shapes are changing and then stabilizing — produces a "splitting" into different histories in different universes, one history for each of the many quantum possibilities that could occur at every instant of time, thereby increasing (by exponential multiplications occurring zillions of times per second!) the number of new universes with varying properties.
      a confession:  I haven't been keeping up-to-date in this area, therefore much that is relevant and important has been omitted in this section and the two below.

      Variations in Properties (Can they be explained by Variations in Strings?)
      Robin Collins explains what strings (if they exist) would and would not control:
      Some of the background laws of physics must be right for the universes generated to be life-permitting.  For example, without the principle of quantization,...; without the Pauli-exclusion principle,.....  These background laws and principles... cannot be explained as a many-universes selection effect. ...  Even if an inflationary/superstring many-universe generator exists, it along with the background laws and principles could be said to be an irreducibly complex system...with just the right combination of laws and fields for the production of life-permitting universes: if one of the components were missing or different, such as Einstein's equation or the Pauli-exclusion principle, it is unlikely that any life-permitting universes could be produced.  In the absence of alternative explanations, the existence of such a system suggests design. .....  {back to Would different universes have different properties?}  { question for reviewers:  Could strings plus a unified theory (to link strings with other requirements) provide what is required in MU?  or if the "other requirements" just vary widely, as proposed in MU? }

      Many Universes (scientific details from Collins and Craig)
      The following excerpts are from Design and the Many-Worlds Hypothesis by Robin Collins:
      It is in the realm of real physical plausibility that a viable inflationary many-universes scenario could be constructed that would account for the fine-tuning of the parameters of physics and the initial conditions of the cosmos. ...  Despite the current popularity of both inflationary cosmology and superstring theory, both are highly speculative. ...  Even if superstring theory or inflationary cosmology turn out to be false, they have opened the door to taking the many-universes explanation of the fine-tuning as a serious physical possibility since some other physical mechanisms could give rise to multiple universes with a sufficiently large number of variations in the parameters of physics.  The only way we could close this door is if we discovered that the ultimate laws of physics did not allow either many-universes or enough variation in the parameters and laws of physics among universes.
      ... [But] there still remains a powerful case for design from physics and cosmology. ...  Much of the evidence for design that we will present cannot be naturally explained by any many-universe scenario, and thus circumvents any objection to design based on the many-universe hypothesis. .....
      Even if a "many-universes generator" exists it seems to need to be "well-designed" in order to produce life-sustaining universes...[by] the expansion of a small region of space into a very large region...[with] the sort of mass-energy we find in our universe. .....
      Finally, it should be stressed that theists need not be opposed to the inflationary many-universe hypothesis.  Indeed, there are several reasons theists could give in support of a theistic version of it.

      and these ideas are from The Teleological Argument and The Anthropic Principle by William Lane Craig:
Inflationary scenarios seem to require the same sort of fine-tuning which some theorists thought these models had eliminated.  For example, in order to proceed appropriately, inflation requires that the two theoretical components of Einstein's cosmological constant, "bare lambda" and "quantum lambda," cancel each other out with an enormously precise though inexplicable accuracy.  A change in the strengths of either aG or aw by as little as one part in 10100 would destroy this cancellation on which our lives depend.

back to How plausible are theories about Many Universes?

      Can we be certain?
      Originally a quoted excerpt was here (from my page asking, Is there proof of God's existence and activity?) but it has been removed because you can just go to the page and read it, if you want.

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Here are other related pages:

Anthropic Principle & Fine Tuning: Multiverse and/or Intelligent Design? — Part 1

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