How would you feel if you purchased a house and you knew the total square footage of the home, but were locked out from access to 70 percent of the house? Wouldn’t you be curious about the nature of that 70 percent? Wouldn’t you attempt to enlist the assistance of a locksmith to gain access to that 70 percent?

How you would feel and respond to being locked out of 70 percent of a house describes well the drive and curiosity astronomers express about the nature of dark energy. As I described in my blog post on April 23, astronomers’ recent analysis of measurements on 1,133,326 galaxies from the Sloan Digital Sky Survey showed that dark energy makes up 69.9 percent of all the stuff of the universe.1 What astronomers know so far about the stuff that comprises 69.9 percent of the universe is that it is an unknown form of energy that permeates the universe’s entire space surface so as to tend to accelerate the universe’s expansion rate. However, even though astronomers are now convinced that dark energy is the dominant component of the universe and that it is the factor either entirely or mostly responsible for the accelerating expansion of the universe, they still know little about its fundamental properties and nature. Hence, a massive search is underway to discover the specific nature of dark energy.

In my April 23rd blog post, I reported on how an analysis of the sample of 1,133,326 galaxies indicated that the acceleration of the cosmic expansion rate was consistent with dark energy being governed by a single nonvarying constant, otherwise known as the cosmological constant. Specifically, the analysis determined that w = -1.042 ± 0.067, where w = P/ρ, where P and ρ denote dark energy’s pressure and energy density respectively, and w exactly = -1.0, which means that dark energy is governed by a single nonvarying constant.

In a paper published in the April 10 issue of the Astrophysical Journal, a team of ten astronomers (including one I knew personally from my time at Caltech), based on measurements of 1,364 supernovae, determined that w = -0.989 ± 0.057.2 Both this determination and the one I reported on in my April 23 blog post were predominantly based on cosmic expansion rate measures of galaxies closer to us than 10 billion light-years. That is, they were determining the properties of dark energy for the last 9 billion years of cosmic history, but not so much for the first 5 billion years of cosmic history.

In the same issue of the Astrophysical Journal, three Chinese astronomers—Ji-Ping Dai, Yang Yang, and Jun-Qing Xia—reconstructed w from the latest observations that included type Ia supernovae, the cosmic microwave background radiation (radiation left over from the cosmic creation event), the universe’s large-scale structure (go here for a mind-blowing video clip of the development of the cosmic large-scale structure), measurements of the cosmic expansion rates based on objects nearer than 9 billion light-years, and baryon acoustic oscillations.3 They found that this reconstruction was consistent with w = -1.0. However, when they added in the baryon acoustic oscillation determinations based on measurements of the Lyman α forest of spectral lines seen in quasars at distances ranging from 9 to 13.5 billion light-years, they noted “a strong preference for the time-evolving behavior of dark energy.”4

In other words, Dai, Yang, and Xia’s study indicates that while dark energy appears to show no evolution over the past 9 billion years, dark energy may indeed be evolving over the first 4.8 billion years of cosmic history. They close their paper with an appeal for astronomers to use the next generation of telescopes to gain more accurate and comprehensive observations of the Lyman α forest of spectral lines in distant quasars to determine the true nature of dark energy.

A team of five astronomers in France, Germany, and the United Kingdom used an entirely different method to constrain w. They used measurements of the thermal Sunyaev Zel’dovich power spectrum to establish that w = -1.10 ± 0.12.5 Three other astronomers explained how the Square Kilometre Array radio telescope (construction to begin in 2019), through measurements of the 21-cm spectral line of neutral hydrogen in very distant quasars and galaxies, will definitely provide an accurate measure of the nature of dark energy during the first few billion years of cosmic history.6

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Figure: Artist’s Impression of the South African Half of the Square Kilometer Array. Image credit: SKA Project Development Office and Swinburne Astronomy Productions

In the last few months, astronomers have made significant progress in determining the nature of dark energy. The new generation of optical telescopes (e.g., the Extremely Large Telescope), infrared telescopes (e.g., the James Webb Space Telescope), and radio telescopes (e.g., the Square Kilometre Array) promises to accurately nail down the properties of dark energy. When that happens, we will know what is going with 70 percent of the universe. That knowledge undoubtedly will unveil yet even more evidence for the fine-tuning design of the universe that makes the existence of physical life, and human life in particular, possible.

Endnotes
  1. Hugh Ross, “Million Galaxy Study Yields Improved Cosmic Creation Model,” Today’s New Reason to Believe (blog), Reasons to Believe, April 23, 2018, http://www.reasons.org/explore/blogs/todays-new-reason-to-believe/read/todays-new-reason-to-believe/2018/04/23/million-galaxy-study-yields-improved-cosmic-creation-model.
  2. D. O. Jones et al., “Measuring Dark Energy Properties with Photometrically Classified Pan-STARRS Supernovae. II. Cosmological Parameters,” Astrophysical Journal 857 (April 10, 2018): id. 51, doi:10.3847/1538-4357/aab6b1.
  3. Ji-Ping Dai, Yang Yang, and Jun-Qing Xia, “Reconstruction of the Dark Energy Equation of State from the Latest Observations,” Astrophysical Journal 857 (April 10, 2018): id. 9, doi:10.3847/1538-4357/aab49a.
  4. Dai, Yang, and Xia, “Reconstruction of the Dark Energy Equation,” page 1 of id. 9.
  5. Boris Bolliet et al., “Dark Energy Constraints from the Thermal Sunyaev Zeldovich Power Spectrum,” Monthly Notices of the Royal Astronomical Society. Published ahead of print, March 29, 2018. doi:10.1093/mnras/sty823.
  6. Bikash R. Dinda, Anjan A. Sen, and Tirthankar Roy Choudhury, “Dark Energy Constraints from the 21-cm Intensity Mapping Surveys with SKA1,” eprint arXiv:1804.11137 (April 2018), https://arxiv.org/abs/1804.11137.

Check out more from Dr. Hugh Ross @Reasons.org

 

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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