Perhaps you’re familiar with Mark Twain’s comment: “The report of my death was an exaggeration” (New York Journal, June 2, 1897). This correction was necessitated by a reporter’s having confused Twain with his seriously ill cousin. How often have my fellow astronomers and I hoped for a similar correction with respect to the big bang! Reporters continue to confuse minor adjustments with the model’s demise.
To scoop the story of the big bang’s having been overturned may be as tempting to journalists as announcing the death of a revered cultural icon, perhaps more so. The magnitude of what’s at stake seems inestimable. Given what the big bang implies about the origin and unfolding of the universe—and about the one ancient account that anticipated its discovery—rigorous and repeated tests of its certainty do seem warranted.
I speak, of course, about the biblical writers who described major features of the big bang thousands of years before scientists could have.1 The advance of technology has allowed for increasingly potent tests of their unprecedented claims. Thus far, each new test—including one of the latest described for you in this article—further solidifies the certainty of their claim about a creation event.
Time Dilation Test of the Big Bang One of the most straightforward and direct substantiations of the big bang creation model is a phenomenon referred to as time dilation. The time dilation test is based on Einstein’s special theory of relativity, founded on the one physics equation nearly everyone knows: E = mc2 (in which E is for energy, m is for mass, and c is for the constant velocity of light). This equation easily ranks as the most firmly established of all the equations in physics. Experiments confirm its veracity to better than twenty places of the decimal.2
From a straightforward application of algebra to this equation, we can deduce that clocks moving at high velocities relative to Earth will advance more slowly in proportion to the speed at which they’re traveling.3
A fundamental characteristic of all big bang models is that the universe began as an infinitesimally small volume and has continuously expanded from its origin event. This cosmic feature predicts that the more distant an object is from Earth, the more rapidly it will appear to be moving away from Earth. Thus, according to Einstein’s theory, clocks in distant galaxies will advance at measurably slower rates than clocks on Earth or in our Milky Way Galaxy (MWG). By comparing/contrasting clocks in distant galaxies to clocks in the MWG, we can directly observe the signature of cosmic expansion, a definitive test of big bang models.
Confirmation from Three Cosmological “Clocks” Many objects in the universe behave as clocks. The best-known examples are the periods of eclipsing binary stars, Cepheid variable stars, galaxy rotation rates, and supernova eruptions. Eclipsing binary stars and Cepheid variable stars are too faint for astronomers to detect and measure in distant galaxies. Likewise, astronomers are able to make accurate measurements of galaxy rotation rates only in relatively nearby galaxies. However, astronomers do have the capacity to observe supernovae in galaxies as far away as 9 billion light-years.
Supernovae
Astronomers have observed several hundred supernova eruption events both in the MWG and in nearby galaxies. Figure 1 shows the light curve of a type Ia supernova eruption in a nearby galaxy. Each of the seven different types of supernovae manifests a distinct light curve over a specific time period.
Figure 1: Light Curve for Nearby Type Ia Supernovae Credit: Hugh Ross
Astronomers have observed that light from supernovae in galaxies billions of light-years away indeed takes extra time to brighten and then become dim, as indicated by their light curves seen from Earth. Based on the measured amount of extra time, we can determine that the cosmos has expanded to its present size from an infinitesimal volume over roughly 13.8 billion years.4
2. Gamma-Ray Bursts
Gamma-ray bursts (GRBs) are extremely energetic and rapid explosions that rank as the most energetic electromagnetic events since the big bang. These blasts, whether from hypernovae or the formation of black holes, last from ten milliseconds to a few hours. A typical GRB releases as much energy in a few seconds as the Sun would emit in ten billion years.
As clearly visible as they may be, GRBs are only rarely observed. The average GRB rate of occurrence is just a few per galaxy per million years. Astronomers have seen them only in very distant galaxies. However, unlike supernovae, astronomers are able to observe gamma-ray bursts at distances beyond 10 billion light-years.
Astronomers have determined, based on statistical distribution, that GRB duration lengthens with increasing distance. The degree of lengthening appears consistent with the expansion of the cosmos from an infinitesimal volume to its present size over 13.8 billion years.5
3. Quasars’ Emission Variability
Because of the relatively small sample size of GRBs, confirmation of the big bang based on them is less robust than the confirmation based on supernova eruptions. However, the GRB test is significant in that it extends the confirmation to greater cosmological distances than are possible based on supernova eruptions alone.
Quasars, on the other hand, are abundant, and like GRBs, they can be observed at distances beyond 10 billion light-years. Quasars are extremely luminous active galactic nuclei powered by supermassive black holes with masses ranging from hundreds of millions to tens of billions of times the Sun’s mass (see figure 2). Thanks to the James Webb Space Telescope and other super telescopes, astronomers have detected and measured quasars as far away as 13.47 billion light-years, a distance that correlates to just 320 million years after the cosmic origin event.6
Figure 2: 3C 273, the Visually Brightest Quasar 3C 273 was the first quasar to be identified. It was discovered by Allan Sandage in the early 1960s. Like most quasars, 3C 273 is firing off a relativistic jet (left). Its jet is more than 200,000 light-years long. Credit: NASA/ Hubble Space Telescope
To date, astronomers have detected and measured over a million quasars. These objects are seen to exhibit light variations as their supermassive black holes draw huge quantities of matter toward their event horizons, where they convert this matter into energy with up to 42% efficiency. (For comparison, the Sun’s nuclear furnace converts matter into energy with 0.07% efficiency.)
Quasar light variations are somewhat predictable, rather than completely random, given that the density of the matter—stars and giant molecular clouds—in the vicinity of the quasars’ supermassive black hole falls within a known range. Therefore, given a large enough sample of quasars, astronomers can use the variability of quasars to test big bang prediction of cosmic time dilation.
The key to using quasar observations as a robust test of cosmic time dilation is sample size. Accuracy depends on a large sample of very distant quasars. The greater the distance of the quasar, the greater the time dilation effect. It is a nonlinear effect. For example, clocks about 8 billion light-years away will run about 10% more slowly than clocks on Earth. Clocks about 13 billion light-years away will run about five times more slowly.
Until recently, astronomers lacked a sufficiently large sample of quasars more distant than 12 billion light-years from which to make quality observations of quasar variability. This lack made it difficult for astronomers to establish, via quasar observations, the certainty of cosmic time dilation.7 Now the lack has been addressed.
Astronomers Geraint Lewis and Brendon Brewer assembled a sample of 190 quasars more distant than 12 billion light-years and monitored their variability for over two decades at multiple wavelengths.8 The variability of these quasars manifested an unambiguous signal of cosmic time dilation. The variability of quasars during the first billion years of cosmic history (quasars more distant than 12.8 billion light-years) measured roughly five times slower than the variability of quasars during the most recent six billion years of cosmic history (quasars less distant than 6.0 billion light-years).
Theological-Philosophical Implications Thanks to the work of Lewis and Brewer, the big bang prediction of cosmic time dilation has been verified for all look-back times. That is, astronomers have observed the expected time dilation effect operating throughout the entire history of the universe. The big bang creation model has successfully passed another test.
The observation of cosmic time dilation also provides yet another confirmation of Einstein’s relativity theory. Over the past century, astronomers and physicists have challenged both the theory and the big bang in dozens of ways. Relativity and big bang cosmology have passed all these tests with flying colors. While further refinements can be anticipated, both have been established beyond reasonable doubt.
All big bang models indicate that the universe began to exist. Thus, the inference of a transcendent cosmic Beginner springs reasonably from the law of cause and effect. Astronomers’ observations of cosmic time dilation by multiple means and at all look-back times further provide evidence of the universe’s age. At ~13.8 billion years old, the universe appears far too young to allow for any credible naturalistic explanation for the origin and history of life. Neither is it as “young” as a mere 6,000 to 10,000 years, as some creationists claim.
Thousands of years before astronomers had even a hint as to the fundamental features of the cosmos, the Bible described at least some of the most significant ones: a beginning that includes the beginning of space and time, matter and energy; physical laws that remain constant throughout history; a pervasive law of decay (entropy); and continual cosmic expansion. On the basis of these facts, we can truthfully say that the Bible has predictive power with respect to science. On the basis of history, we have good reasons to believe that the Bible is, indeed, the Word of God, trustworthy in everything it says about both physical and spiritual matters.
Sidney Coleman and Sheldon L. Glashow, “Cosmic Ray and Neutrino Tests of Special Relativity,” Physics Letters B 405, nos. 3–4 (July 24, 1997): 249–252, doi:10.1016/S0370-2693(97)00638-2; P. W. Cattaneo, “Testing the Special Relativity Theory with Neutrino Interactions,” Europhysics Letters 99, no. 5 (September 2012): id. 51001, doi:10.1209/0295-5075/99/51001; P. Delva et al., “Test of Special Relativity Using a Fiber Network of Optical Clocks,” Physical Review Letters 118, no. 22 (June 2, 2017): id. 221102, doi:10.1103/PhysRevLett.118.221102.
For clocks moving at high velocities relative to Earth, time will be slowed a factor of 1 divided by the square root of (1 – v2/c2), where v is the velocity of the clock. For example, time for a clock moving at half the velocity of light relative to Earth will be “stretched” by a factor of 1.154.
S. Blondin et al., “Time Dilation in Type Ia Supernova Spectra at High Redshift,” Astrophysical Journal 682, no. 2 (August 1, 2008): 724–736, doi:10.1086/589568; Ryan J. Foley et al., “A Definitive Measurement of Time Dilation in the Spectral Evolution of Moderate-Redshift Type Ia Supernova 1997ex,” Astrophysical Journal Letters 626, no. 1 (June 10, 2005): L11–L14, doi:10.1086/431241; Bruno Leibundgut et al., “Time Dilation in the Light Curve of the Distant Type Ia Supernova SN 1995K,” Astrophysical Journal Letters 466, no. 1 (July 20, 1996): L21–L24, doi:10.1086/310164; A. G. Riess et al., “Time Dilation from Spectral Feature Age Measurements of Type Ia Supernovae,” Astronomical Journal 114, no. 2 (August 1997): 722–729, doi:10.1086/118506; G. Goldhaber et al., “Timescale Stretch Parameterization of Type Ia Supernova B-Band Light Curves,” Astrophysical Journal 558, no. 1 (September 1, 2001): 359–368, doi:10.1086/322460; Bruno Leibundgut, “Cosmological Implications from Observations of Type Ia Supernovae,” Annual Review of Astronomy and Astrophysics 39 (September 2001): 67–98, doi:10.1146/annurev.astro.39.1.67.
Amitesh Singh and Shantanu Desai, “Search for Cosmological Time Dilation from Gamma-Ray Bursts—a 2021 Status Update,” Journal of Cosmology and Astroparticle Physics 2020 (February 2022): id. 10, doi:10.1088/1475-7516/2022/02/010; Mariusz Tarnopolski, “Can the Cosmological Dilation Explain the Skewness in the Gamma-Ray Burst Duration Distribution?” Astrophysical Journal 897, no. 1 (July 1, 2020): id. 77, doi:10.3847/1538-4357/ab8eb1.
B. E. Robertson, “Identification and Properties of Intense Star-Forming Galaxies at Redshifts z >10,” Nature Astronomy 7 (April 4, 2023): 611–621, doi:10.1038/s41550-023-01921-1.
M. R. S. Hawkins, “On Time Dilation in Quasar Light Curves,” Monthly Notices of the Royal Astronomical Society 405, no. 3 (July 2010): 1940–1946, doi:1111/j.1365-2966.2010.16581.x.
Geraint F. Lewis and Brendon J. Brewer, “Detection of the Cosmological Time Dilation of High-Redshift Quasars,” Nature Astronomy 7 (July 3, 2023) online release ahead of print issue, doi:10.1038/s41550-023-02029-2.
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