Advancing science continues to reveal that we live in a just-right universe. Our universe exhibits three truly astounding features: it is presently extremely large, every region of the universe is thermally connected to every other region, and its shape is geometrically flat. All of these amazing cosmic features are necessary for physical life to exist in the universe and without cosmic inflation, we wouldn’t have them.

Life-Friendly Features
Despite the vast stretches of space between stars and galaxies, every region of the universe manifests the same overall temperature. Without this temperature similarity and temperature smoothness, the universe would be much more clumpy than it is and the kind of galaxy cluster, galaxy, star, and planetary system that physical life requires would never exist. The vast stretches of space that currently exist between stars and galaxies mean that it is possible for life—especially advanced life—to exist somewhere in the universe where deadly radiation and gravitational disturbances from adjacent stars and galaxies do not pose a threat. If the universe were spherically shaped rather than flat (see figure below), the universe would expand from the cosmic creation event, stop expanding, and collapse back in on itself before a galaxy, star, and planetary system could form in which physical life could possibly exist. If the universe were hyperbolically shaped rather than flat (see figure below), the universe would expand so quickly from the cosmic creation event that galaxies, stars, and planets would be unable to form.


Figure: Possible Cosmic Geometries. Only in a universe that is very close to possessing a flat geometry will galaxies, stars, and planets form that are necessary to make life possible. Image credit: NASA. Diagram credit: Hugh Ross

Cosmic Inflation Necessary for Life
The thermal connectedness, vast size, and flat geometry of the universe that presently exist would be impossible if the universe expanded from the cosmic creation event at a rate that never exceeded the velocity of light. An extremely brief inflation episode, lasting from less than 10-36 to 10-32 seconds after the cosmic creation event, where the universe expands by at least a factor of 1026 (from smaller than a proton to about the size of a grapefruit, or about a trillion trillion times faster than the velocity of light) when the universe is very young (10-36 to 10-32 seconds old) solves all three problems.

First, the hyper-accelerated expansion of space during a brief inflation event would stretch out any initial variations in matter, density, or temperature, such that the universe becomes homogeneous and uniform on large size scales—on the largest size scale to about one part in one hundred thousand. Second, temperature differences among regions in the universe would get reduced to only about one part in a hundred thousand. And third, the curvature of space would get reduced to where it measures to be flat to at least four places of the decimal.

Observational Confirmation of Cosmic Inflation
These outcomes are not only what is needed to make life in the universe possible, but they’re also what astronomers have determined by their measurements to be true about the universe. The ongoing Sloan Digital Sky Survey of galaxies and galaxy clusters1 and the Planck2 and WMAP3 maps of the cosmic microwave background radiation (CMBR) have yielded undeniable affirmations.

Another strong affirmation comes from measurements of the scalar spectral index. A value for the scalar spectral index, ns, arises from accurate measurements of the E-polarization mode in maps of the CMBR.

For a universe with no inflation event, ns equals 1.0 or greater. For a universe that manifests a simple inflation event, ns equals exactly 0.95. For a universe that has experienced a complex inflation event, ns equals 0.96–0.97.

An analysis of the two best maps to date of the CMBR, plus the best map of the baryon acoustic oscillation, yielded a value for ns = 0.9658 ± 0.0038.4 This measurement is a major improvement on the previous best measure of ns that I wrote about in my book The Creator and the Cosmos, 4th edition: ns = 0.9593 ± 0.0067.5 The error (uncertainty) in the new measure, ±0.0038, implies there is less than 1 chance in 6 quintillion (1 chance in 6,000,000,000,000,000,000) that the universe did not experience an inflation event very early in its history.This measure of certainty that the universe must have experienced an inflation event compares with 1 chance in 900 million that it did not, based on the previous best measure.

The error measure, ±0.0038, also implies there is less than 1 chance in 16,000 that the universe experienced a simple—as opposed to a complex—inflation event. However, in the physical sciences an event is not considered certain unless the probability of an alternative outcome is less than 1 chance in 1,750,000. Therefore, astronomers have yet to determine exactly what kind of inflation occurred in the very early history of the universe. It appears, though, regardless of what kind of inflation occurred, the event must have been fine-tuned for physical life in the universe to be possible.


Readers wanting a more in-depth description and explanation of how an early cosmic inflation event must be fine-tuned to make physical life possible will find it in my book The Creator and the Cosmos4th edition, 68–69.

Check out more from Reasons to Believe

  1. Beth A. Reid et al., “Cosmological Constraints from the Clustering of the Sloan Digital Sky Survey DR7 Luminous Red Galaxies,” Monthly Notices of the Royal Astronomical Society 404, no. 1 (May 2010): 60–85, doi:10.1111/j.1365-2966.2010.16276.x; Max Tegmark et al., “Cosmological Constraints from the SDSS Luminous Red Galaxies,” Physical Review D 74, no. 12 (August 2006): id. 123507, doi:10.1103/PhysRevD.74.123507.
  2. P. A. R. Ade et al., Planck Collaboration, “Planck 2015 Results. XIII. Cosmological Parameters,” Astronomy & Astrophysics 594 (October 2016), id. A13, doi:10.1051/0004-6361/201525830.
  3. Gary Hinshaw et al., “Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Parameter Results,” Astrophysical Journal Supplement Series 208, no. 2 (October 2013): 1, id. 19doi:10.1088/0067-0049/208/2/19.
  4. Narges Rashidi and Kourosh Nozari, “Gauss-Bonnet Inflation after Planck2018.” Preprint, submitted January 20, 2020. https://arXiv:2001.07012v1.
  5. Hugh Ross, The Creator and the Cosmos: How the Latest Scientific Discoveries Reveal God, 4th ed. (Covina, CA: RTB Press, 2018), 69.
  6. Kevin Dowd et al., “How Unlucky is 25-Sigma?” Preprint, submitted March 24, 2008.


About The Author

Dr. Hugh Ross

Reasons to Believe emerged from my passion to research, develop, and proclaim the most powerful new reasons to believe in Christ as Creator, Lord, and Savior and to use those new reasons to reach people for Christ. I also am eager to equip Christians to engage, rather than withdraw from or attack, educated non-Christians. One of the approaches I’ve developed, with the help of my RTB colleagues, is a biblical creation model that is testable, falsifiable, and predictive. I enjoy constructively integrating all 66 books of the Bible with all the science disciplines as a way to discover and apply deeper truths. 1 Peter 3:15–16 sets my ministry goal, "Always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have. But do this with gentleness and respect, keeping a clear conscience." Hugh Ross launched his career at age seven when he went to the library to find out why stars are hot. Physics and astronomy captured his curiosity and never let go. At age seventeen he became the youngest person ever to serve as director of observations for Vancouver's Royal Astronomical Society. With the help of a provincial scholarship and a National Research Council (NRC) of Canada fellowship, he completed his undergraduate degree in physics (University of British Columbia) and graduate degrees in astronomy (University of Toronto). The NRC also sent him to the United States for postdoctoral studies. At Caltech he researched quasi-stellar objects, or "quasars," some of the most distant and ancient objects in the universe. Not all of Hugh's discoveries involved astrophysics. Prompted by curiosity, he studied the world’s religions and "holy books" and found only one book that proved scientifically and historically accurate: the Bible. Hugh started at religious "ground zero" and through scientific and historical reality-testing became convinced that the Bible is truly the Word of God! When he went on to describe for others his journey to faith in Jesus Christ, he was surprised to discover how many people believed or disbelieved without checking the evidence. Hugh's unshakable confidence that God's revelations in Scripture and nature do not, will not, and cannot contradict became his unique message. Wholeheartedly encouraged by family and friends, communicating that message as broadly and clearly as possible became his mission. Thus, in 1986, he founded science-faith think tank Reasons to Believe (RTB). He and his colleagues at RTB keep tabs on the frontiers of research to share with scientists and nonscientists alike the thrilling news of what's being discovered and how it connects with biblical theology. In this realm, he has written many books, including: The Fingerprint of God, The Creator and the Cosmos, Beyond the Cosmos, A Matter of Days, Creation as Science, Why the Universe Is the Way It Is, and More Than a Theory. Between writing books and articles, recording podcasts, and taking interviews, Hugh travels the world challenging students and faculty, churches and professional groups, to consider what they believe and why. He presents a persuasive case for Christianity without applying pressure. Because he treats people's questions and comments with respect, he is in great demand as a speaker and as a talk-radio and television guest. Having grown up amid the splendor of Canada's mountains, wildlife, and waterways, Hugh loves the outdoors. Hiking, trail running, and photography are among his favorite recreational pursuits - in addition to stargazing. Hugh lives in Southern California with his wife, Kathy, and two sons.

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