A superintellect has monkeyed with physics, as well as with chemistry and biology.
--Sir Fred Hoyle1
For decades scientists of all disciplines recognized exquisite fine-tuning in the laws governing the universe in order to permit life. If the individual strengths or ratios of the four fundamental forces of nature observed today -- gravity, electromagnetic force, and the strong and weak nuclear forces -- were minutely stronger or weaker, life becomes impossible. The same constraint also applies to the fundamental parameters of the universe, such as the mass of the electron, the number of large space dimensions, or the expansion rate. Nontheistic scientists' responses to such fine-tuning generally fall into two categories.
One response is to hope and search for some physical principle that forces these fine-tuned quantities to assume the values they do. For example, it takes fine-tuning to make a long, thin rod stand on its end and not fall over. However, if the same rod is held at the top so that it cannot tip, the appearance of fine-tuning disappears because the position of the rod can only assume one value. To these scientists' dismay, this "solution" to the fine-tuning "problem" seems increasingly unlikely.
The second category of explanations, growing in popularity, invokes the idea of a multiverse. Naturalistic scientists posit that instead of this universe being all that exists, there also exists a multitude of other "universes" -- each exhibiting different laws and fundamental parameters. These different universes never contact one another, so it is impossible to detect or to directly measure any of them. However, if this multitude of universes exists, scientists argue that the required fine-tuning for life in this universe could simply be a consequence of life arising in the universe where it is possible. As summarized by the Weak Anthropic Principle (WAP), this universe must appear designed for life or else we would not be here to observe it.
While at first glance the multiverse proposal sounds ad hoc, scientists point to two lines of support. First, recent evidence strongly points to a period of hyperexpansion -- dubbed inflation -- very early in the universe when the universe grew by a factor of 1030 in an infinitesimal fraction of a second.2 Some speculated theoretical modeling suggests that the physics causing inflation results in many different inflating "bubbles."3 One bubble contains this universe, but other bubbles could contain other universes.
Second, the two most tested and verified scientific theories, general relativity and quantum mechanics, are mutually exclusive if only four space-time dimensions operate in the early universe. How could both be true? As scientists currently understand the universe, string theory4 provides a superior model that successfully incorporates both general relativity and quantum mechanics. However, the possible solutions to the equations of string theory are about 10500, each with different laws, dimensionalities, and parameters. Cosmologists point to this plethora of possible solutions as possible universes for inflation to populate. (For a particularly enthusiastic explanation, read The Cosmic Landscape.5) Interestingly, none of the explored solutions match this universe, indicative of the fine-tuning exhibited by the universe.
Part of the favor that multiverse proposals garner derives from the notion that strictly natural theories are inherently more scientific than those which include supernatural causation. However, all multiverse models can be recast in terms of a single universe. Although possible, the multiverse proposal rests completely on speculated theoretical calculations -- to date, no experimental or observational data exists that differentiates between a single, finely tuned universe and any of the multiverse speculations.
See "How Does A Christian Respond to the Multiverse Concept?" for a more thorough response.
Fred Hoyle, "The Universe: Past and Present Reflection," Annual Reviews of Astronomy and Astrophysics 20 (1982): 16.
- The three-year data release from the Wilkinson Microwave Anisotropy Probe (WMAP) provides compelling evidence that this period of faster-than-light expansion did indeed occur when the universe was approximately 10-34 seconds old. See http://map.gsfc.nasa.gov/m_mm.html.
- Alan H. Guth, The Inflationary Universe (Reading, MA: Helix Books, 1997).
- Hugh Ross, Beyond the Cosmos (Colorado Springs, CO: NavPress, 1999), 36-46.
- Leonard Susskind, The Cosmic Landscape (New York: Little, Brown, 2006).