12 thoughts on “Age of universe — implications?”

1. As Carl Sagan noted:

   To discover that the Universe is some 8 to 15 billion and not 6 to 12 thousand years old* improves our appreciation of its sweep and grandeur; to entertain the notion that we are a particularly complex arrangement of atoms, and not some breath of divinity, at the very least enhances our respect for atoms; to discover, as now seems probable, that our planet is one of billions of other worlds in the Milky Way Galaxy and that our galaxy is one of billions more, majestically expands the arena of what is possible; to find that our ancestors were also the ancestors of apes ties us to the rest of life and makes possible important—if occasionally rueful—reflections on human nature.

   * “No thinking religious person believes this. Old hat,” writes one of the referees of this book. But many “scientific creationists” not only believe it, but are making increasingly aggressive and successful efforts to have it taught in the schools, museums, zoos, and textbooks. Why? Because adding up the “begats,” the ages of patriarchs and others in the Bible, gives such a figure, and the Bible is “inerrant.” — Demon-Haunted World: Science as a Candle in the Dark by Carl Sagan

2. Since finding the expansion rate of the cosmos is key to determining the age of the universe, I found this recent Space.com article interesting: “Does Dark Energy Exist?”

   Two competing teams, using different telescopes, different datasets and different methodologies, were independently coming to the same conclusion. Our universe wasn’t slowing down, but speeding up.

   They published their work almost 20 years ago. In the meantime, after several independent lines of evidence all pointed to the same conclusion, they shared in a Nobel Prize for their unexpected discovery.

   The name for that observed phenomenon — dark energy — sticks with us today, but we still don’t understand it. We don’t know why the expansion of the universe is accelerating, but we do know that it does accelerate.

   [Paul Sutter is an astrophysicist at The Ohio State University and the chief scientist at COSI Science Center. Sutter is also host of Ask a Spaceman, We Don’t Planet, and COSI Science Now. Sutter contributed this article to Space.com’s Expert Voices: Op-Ed & Insights.]

3. Pondering an expanding universe billions of years old tends to raise the question of our place in the cosmos — of both the Earth and our species.¹ This July 27, 2017, Space.com article “Why Looking for Aliens Is Good for Society (Even If There Aren’t Any)” addresses some implications of that perspective: “a sense of deep, or big, history.”

   It is simply not possible to consider searching for life on Mars, or on a planet orbiting a distant star, without moving away from the narrow Earth-centric perspectives that dominate the social and political lives of most people most of the time. Today, the Earth is faced with global challenges that can only be met by increased international cooperation. Yet around the world, nationalistic and religious ideologies are acting to fragment humanity. At such a time, the growth of a unifying cosmic perspective is potentially of enormous importance.

   In the early years of the space age, the then US ambassador to the United Nations, Adlai Stevenson, said of the world: “We can never again be a squabbling band of nations before the awful majesty of outer space.” Unfortunately, this perspective is yet to sink deeply into the popular consciousness. On the other hand, the wide public interest in the search for life elsewhere means that astrobiology can act as a powerful educational vehicle for the popularisation of this perspective.

   [1] As noted in another Space.com article:

   We orbit a typical star, in a typical spiral galaxy, in a typical branch of a typical supercluster. Our planet and its evolutionary leap to intelligent beings could’ve occurred in any old spot around the cosmos and we ought to have come to the same conclusions about the big science questions: the Big Bang, dark energy, the cosmic web, the works.

4. Over the weekend, I started reading some books¹ by Lawrence Krauss. So, I learned about The Origins Project.

   By casting a sharp lens on the origins of the universe, life, disease and complex social systems, the Origins Project develops new knowledge and inspires the public on fundamental questions that are at the heart of the 21st Century’s greatest challenges.

   [1]

   • Quantum Man: Richard Feynman’s Life in Science (2011), Norton and Co.
   • A Universe from Nothing: Why There Is Something Rather Than Nothing (2012), Atria Books
   • The Greatest Story Ever Told—So Far: Why Are We Here? (2017), Atria Books

5. Today Space.com posted an article “WMAP Team Wins $3 Million Breakthrough Prize in Fundamental Physics” (12-4-2017) summarizing two “big science” projects which contributed to measurement of the Cosmic Microwave Background (CMB) and determination of the age of the universe.

   Those folks worked on NASA’s WMAP space mission [Wilkinson Microwave Anisotropy Probe], which was awarded the 2018 Breakthrough Prize in Fundamental Physics today (Dec. 3) during a ceremony in Palo Alto, California.

   From 2001 to 2009, WMAP mapped the cosmic microwave background (CMB) — the light left over from the Big Bang — with unprecedented precision. This work allowed scientists to nail down the age of the universe (about 13.8 billion years), its rate of accelerating expansion (roughly 70 kilometers per second per megaparsec) and its basic composition (about 5 percent “normal” matter, 24 percent dark matter and 71 percent dark energy).

   “I see the legacy as establishing the standard model and making cosmology quantitative,” Spergel told Space.com. “There have been improvements in the measurements since WMAP, but I think we provided a very solid base that the field is building on.”

   Those improvements were provided largely by the European Space Agency’s Planck spacecraft, which mapped the CMB from 2009 to 2013. Planck’s data have reinforced and refined, rather than challenged, the WMAP results.

6. So, some religious conservatives dispute the scientific consensus on the age of the Earth and the universe — that is strange. But a Space.com article today — “8 Times Flat-Earthers Tried to Challenge Science (and Failed) in 2017” — reminds me that there’s an even stranger group, namely, those who still play with the notion that the Earth is flat. Whether as performance art or for publicity, eh.

7. Yesterday, Space.com posted this interesting article: Stephen Hawking Is Worried About Humanity’s Future.

   After a brief profile of Hawking’s second-ever episode of “Favorite Places,” an Emmy-winning series, which premieres on CuriosityStream.com on January 8, the article includes some quotes on the age of the universe and our origins.

   “In order for a sun and planets like ours to be born, an entire generation of giant stars had to live and die before them,” he says. “And here is a remarkable thing: It takes around 7 billion years for that to happen. Our sun is just over 4.5 billion years old and the universe is only 13.7 billion. So, you and I came into existence at precisely the time it became possible, and not a moment later.”

   It seems miraculous, Hawking says, but attributing it to miracles makes it unknowable, and he needs to know.

   To Proxima Centauri and beyond!

8. Reference: Forbes > “The Expanding Universe Might Not Depend On How You Measure It, But When” by Ethan Siegel, Senior Contributor (February 7, 2020).

   So, there’s interplay between the age of the universe and the expansion rate (Hubble constant). Science communicator Ethan Siegel’s latest Forbes article summarizes research on the different ways of measuring how fast the universe is expanding. Unlike in my post “Wine before time itself – stars older than the universe?” he says that uncertainties [wiggle-room] in the distance ladder do not account for the different values.

   No sources of error have been identified that could explain the discrepancy, with multiple independent lines of evidence existing for both sets of results. Recently, however, a very clever new test of the Universe’s expansion rate has been devised and leveraged, and it appears to offer a clue like none before: the same test favors different values at late versus early times. Perhaps expanding Universe depends on when, rather than how, you measure it.

   His article contains several visualizations and diagrams.

   One of the most puzzling facts about the Universe is that different ways of measuring how fast it’s expanding yield different results. It’s not that there are two ways to measure it and they don’t agree; it’s that there are perhaps a dozen different ways of measuring it, and they yield two different sets of results. Both of them require a Universe filled with normal matter, dark matter, and dark energy, but their preferred values differ by about 9%: much greater than the uncertainties involved.

   About a decade ago, there were three independent sets of measurements that all revealed properties of the Universe in comprehensive, complementary but independent ways: the fluctuations in the cosmic microwave background; the clustering of galaxies, galaxy clusters, and other features of the Universe’s large-scale structure; and direct measurements of distances-and-redshifts of individual objects, from individual nearby stars to distant supernovae across the Universe.

   The biggest achievement of the new paper is to factor in the effect of cosmic voids: the vast and largely empty regions of space that exist between the strands of the cosmic web that trace out our Universe’s large-scale structure.

   It’s definitely the case that different methods of measuring the expanding Universe give different values, but this is the first time that the same method has yielded two different results depending on whether you look at the full data set or the late-time measurements alone.

9. So, for decades, I’ve wondered about cosmologists’ and physicists’ models of the universe, in particular, assumptions on the uniformity of stuff – average density of matter. Thinking like a physicist involves models that are good enough in approximating reality, reducing complexity to permit solutions. What could possibly go …

   Phys.org > “Solved: The mystery of the expansion of the universe” by University of Geneva (March 10, 2020).

   The Earth, solar system, the entire Milky Way and the few thousand galaxies closest to us move in a vast “bubble” that is 250 million light years in diameter, where the average density of matter is half as high as for the rest of the universe. This is the hypothesis advanced by a theoretical physicist from the University of Geneva (UNIGE) [set out in the journal Physics Letters B] to solve a conundrum that has been splitting the scientific community for a decade: At what speed is the universe expanding?

   Model frameworks

   Hubble-Lemaître law, including the Hubble constant (H0).

   Calculating the expansion rate: (1) analysis of the cosmic microwave background, (2) study of supernovae that appear sporadically in distant galaxies.

   Assumptions: the universe is homogeneous and isotropic at some vast enough scale – for “[cosmic] volumes thousands of times larger than a galaxy.”

   Related posts

   • Photographing a black hole? – comment re Friedmann’s equations.

   The Friedmann equations start with the simplifying assumption that the universe is spatially homogeneous and isotropic, i.e. the cosmological principle; empirically, this is justified on scales larger than ~100 Mpc.

   • Vocabulary at the end of the verse which notes this Space.com article > “The (Cosmological) Axis of Evil” by Paul Sutter (June 29, 2017) in which Sutter says:

   When it comes to cosmology, two assumptions make the difference between a world of math-pain and math-paradise: that our universe is homogenous and isotropic. Homogenous means that, at big enough scales, one patch of the universe is roughly like any other patch. Obviously you have to go to beefy enough scales to make this work (for example, the Earth is very different than the sun), and for our universe that happens at around 200 million light-years. Isotropic means that the cosmos looks pretty much the same no matter what direction you look in — again, over sufficiently large distances.

   With these two assumptions in place, the math of GR is slightly less torturous and progress (i.e., generating testable hypotheses and confirming/refuting them with experiment) can be made.

   • Beyond the Milky Way — a game-changing discovery – comment re the universe is homogeneous and isotropic when averaged over very large scales.

   “The simplest assumption to make is that if you viewed the contents of the universe with sufficiently poor vision, it would appear roughly the same everywhere and in every direction,” NASA stated. “That is, the matter in the universe is homogeneous and isotropic when averaged over very large scales. This is called the cosmological principle.”

   One example of the cosmological principle at work is the cosmic microwave background, radiation that is a remnant of the early stages of the universe after the Big Bang. Using instruments such as NASA’s Wilkinson Microwave Anisotropy Probe, astronomers have found the CMB is virtually identical wherever one looks.

10. Re the cosmic expansion rate … general relativity … first Friedmann equation … standard candles (with the assumption that light emitted from a source always spreads out in a spherical shape) and standard rulers …

    • Forbes > “Ask Ethan: Could Measurement Inaccuracies Explain Our Cosmic Controversies?” by Ethan Siegel (Oct 23, 2020)

    For the expanding Universe, we typically assume the following:

    • the laws of physics are the same, everywhere, for all observers at all times,
    • that General Relativity, as put forth by Einstein, is our theory of gravitation,
    • that the Universe is isotropic, homogeneous, and expanding,
    • and that light obeys Maxwell’s laws of electromagnetism when it behaves classically, and the quantum rules that govern it (quantum electrodynamics) apply when it exhibits quantum behavior.

    A small part of that redshift (or blueshift, if the object is moving towards us) will be due to the gravitational influence of all the other objects around it: what astronomers call “peculiar velocity.”

    But that effect is always superimposed over the expansion of the Universe, which is primarily responsible — especially at large distances — the redshifts we observe.

    Earlier this month, exactly that test was performed, as astronomer Ian Steer leveraged the NASA/IPAC Extragalactic Database of Distances (NED-D) to tabulate multiple distances for 12,000 separate galaxies, using a total of six different methods. In particular, a couple of key galaxies frequently used as “anchor points” in constructing the cosmic distance ladder, like the Large Magellanic Cloud and Messier 106, were included. The results were spectacular: all six methods (spanning 77 various indicators) yielded consistent distances for each of the examined cases. It’s the largest independent test like this we’ve ever performed, and it shows that — to the limits of what we can tell — we don’t appear to be fooling ourselves about cosmic distances, after all.

11. As if a reply to Ethan Siegel’s article of October 23, 2020 – “Could Measurement Inaccuracies Explain Our Cosmic Controversies?” (noted above), Paul Sutter’s latest Space.com article posits that: “Maybe we just don’t understand some cosmic phenomena as well as we think we do.”

    • Space.com > “Is there really a ‘crisis’ in cosmology?” by Paul Sutter (July 26, 2021) – includes a video monolog on the question.

    (quote) To measure the age of the universe, you have to know its expansion history. And to get the expansion history, you need to do some mathematical modeling. Mathematical modeling is pretty common in science (indeed, it basically is science), …

    Sutter discusses the standard two ways of calculating the expansion rate, as noted above (March 10, 2020):

    Calculating the expansion rate: (1) analysis of the cosmic microwave background, (2) study of supernovae that appear sporadically in distant galaxies.

    But not particularly more basic assumptions:

    Assumptions: the universe is homogeneous and isotropic at some vast enough scale – for “[cosmic] volumes thousands of times larger than a galaxy.”

    He does, however, note the need to introduce a dark energy profile when using the CMB method.

    So, based on the Big Bang model (particularly quantum plasma theory):

    • Use Einstein’s theory of general relativity -> the Friedmann equations.
    • Measure the stuff – using two primary methods:

    (1) Measure the CMB and add in the amount of dark energy.

    or

    (2) Measure the expansion rate in the nearby universe using standard candles, like Type Ia supernovas.

    Sutter discounts flaws in CMB measurement as an explanation of any discrepancy (albeit relatively small) in predictions of the two methods. Maybe there’s “wiggle room” in the dark energy mix. Or variability. Maybe the need for more complicated Friedmann equations.

    A more likely explanation (a simpler solution to the “crisis”), he concludes, is “a dash of uncertainty in modeling supernovas.” Not a lot of data points either – from only 6 key galaxies.

    (quote) The most boring way to solve the crisis is to admit that supernovas aren’t as powerful a probe of the expansion rate as we would hope. But that wouldn’t produce nearly as many papers as a crisis, and our cosmological conferences would be a lot less entertaining.

    Models within models all the way down, eh. A cow is not really a sphere … not really a point …

    Related posts

    • When conservation of energy goes out the window? > Notes > “The Hardest Thing To Grasp In Physics? Thinking Like A Physicist” by Chad Orzel (Aug 29, 2016).

    • Wine before time itself – stars older than the universe?

12. Continuing research on the mass (energy) mix of the universe, critical to estimating its age …

    I like the term “undetectable” rather than “dark” energy. Much like “dark” matter is better termed “invisible” – invisible to the entire electromagnetic spectrum.

    • Space.com > “Phantom energy and dark gravity: Explaining the dark side of the universe” by Paul Cockburn, All About Space magazine (June 30, 2021) – Understanding the ‘undetectable’ cosmos could lead to significant changes in some highly cherished theories about space-time [Einstein’s theory].

    Research into the universe’s energy accounting (allocation) – refining models of the “dark” aspects of the universe:

    • Emergent gravity [gravity is not a fundamental force (interaction) after all] … dark (“modified”) gravity …

    • Dark energy [“assumed to be the foot on the accelerator causing the universe to expand”] -> phantom energy … dark radiation [undiscovered subatomic particles, perhaps sterile neutrinos] …

    Related posts

    • Hidden in plain sight — dark matter

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