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A shelf life for the universe?

While Sean Carroll’s latest chat-from-home presentations on his YouTube channel address the “biggest ideas” in the universe, other theoretical physicists explore whether our mind-boggling big universe has sort of a shelf life. A final reservation date, so to speak, at a fantastically socially-distanced restaurant at the end of the universe.

Reference: Forbes > “What Will It Be Like When We Reach The End Of The Universe?” by Ethan Siegel, Senior Contributor (May 6, 2020).

It’s remarkable how our understanding of the universe has changed over recorded history.[1] Once viewed as so perfect and eternal – a timeless realm, the universe may in fact have an expiration date. But in what sense? And there’s no need to panic. Even the demise of life on Earth when the Sun becomes a red giant is likely one or two billion years away.

The Forbes article referenced above is a good overview of research regarding the fate of the universe, the various scenarios, and whether “heat death” remains the most likely projection.[2] It includes some excellent visuals and contains a socially-distanced presentation (video) sponsored by the Perimeter Institute, as part of its reimagined lecture series, by astrophysicist Dr. Katie Mack, basically promoting her new book (a labor of love) The End of Everything: (Astrophysically Speaking) which will be released in August.

[Teaser] From one of the most dynamic rising stars in astrophysics, an accessible and eye-opening look at five ways the universe could end, and the mind-blowing lessons each scenario reveals about the most important concepts in cosmology.

… a mind-bending tour through five of the cosmos’s possible finales: the Big Crunch, Heat Death, the Big Rip, Vacuum Decay (the one that could happen at any moment!), and the Bounce.

YouTube > Perimeter Institute for Theoretical Physics > “A Conversation with Katie Mack” (May 6, 2020)

In a special live webcast, theoretical cosmologist and science communicator Katie Mack — known to her many Twitter followers as @astrokatie — will answer questions about her favorite subject: the end of the universe. Mack is an Assistant Professor at North Carolina State University whose research investigates dark matter, vacuum decay, and the epoch of reionization. Mack is a popular science communicator on social media, and has contributed to Scientific American, Slate, Sky & Telescope, Time, and Cosmos.
Our deepest galaxy surveys can reveal objects tens of billions of light years away, but there aremore galaxies within the observable Universe we still have yet to reveal between the most distant galaxies and the cosmic microwave background, including the very first stars and galaxies of all. As the Universe continues to expand, the cosmic frontiers will recede to ever greater distances.
Update 5-21-2020

So, how does a mind-boggling cosmology connect with our search for meaning and purpose? A framework of such vast scales (10^-n – 10^n) with an end to the universe or to time itself – what does that do to us? Is this quest for cosmic specialness a timeless journey as well?

Well, that’s what physicist Brian Greene discusses in his new book Until the End of Time: Mind, Matter, and Our Search for Meaning in an Evolving Universe. Here’s a YouTube conversation about the book.

YouTube > Pioneer Works > “Until the End of Time: Brian Greene in Conversation with Janna Levin” (April 23, 2020).

Brian Greene, the world-renowned physicist and best-selling author of The Elegant Universe, launches his captivating new book Until the End of Time: Mind, Matter, and Our Search for Meaning in an Evolving Universe at Pioneer Works. Join Janna Levin, our Director of Sciences, in conversation with Brian Greene to grasp and gain a refined appreciation for our fleeting, but utterly exquisite, moment in the cosmos.

This project is supported by Science Sandbox, a Simons Foundation initiative dedicated to engaging everyone with the process of science.

Here’re some notes after watching the video.

A perspective on the journey toward an answer … highly reductionist but with synthesis [cf. Sean Carroll’s poetic naturalism]. Deeper understanding … scales of meaning … [book] The Denial of Death by Ernest Becker [3] … awareness of mortality, what does that do to us? Our lifespan and interplay with life cycle of universe, that physics explores an end to the universe.

We are the product of purposeless mindless laws of physics playing themselves out on our bags of particles. That perspectives changes the way we search for meaning and purpose. Manufacture our own meaning, coherence, make sense of existence. That doesn’t make it artificial but more noble, rather than accepting purpose thrust upon us from outer world. Doesn’t lead to darkness.

Re entropy, pockets of order – stars, so not total loss of structure. Entropic two-step. Big Bang as highly ordered start. Currently laws of physics do not define initial conditions, just the evolution from that. [Personally, I like the notion of evolution (from a Big Bang, for example) as the most efficient way to disperse energy across the universe.]

Challenge to explain life, consciousness. (Levin: A map of the external world evolving to a map of the internal world. A map because there’s just too much information.) Challenge of tethering that limited map to physical processes. (Levin: Free will debate.) Utterly spectacular that same laws for objects orchestrate consciousness (versus a magical impetus). A continuity. Of unfolding. A kind of freedom that distinguishes us from the inanimate world. Not freedom from laws of physics but a freedom in our range of behaviors.

A different kind of gratification than the notion of free will. A view of our role in the world. (Levin: Development of language and story telling.) About the mysteries that excite us, in different communities. Why we spend time doing that. A realm where people can make up (all kinds of) so so tales.

Some research that story telling prepares us for encounters in the real world. Safe rehearsals so to speak. [Cf. neuroscience.] And competition among those narratives. Visions of the world. The limits of language to describe some experiences. (Levin: And the dark side of arbitrary projections …) [Risks of imagination gone wild.]

(Levin: Myth and religion.) Being a spiritual person vs. a religious one. Religious journey of his older brother. (Levin: Paths to meaning.) A resonance between questions in each journey, physics and religion. [Cf. Two cultures redux.] (Levin: Survival value … adaptive role …) Utility of junk food as preying on past adaptive utility of energy rich foods in evolution. Music … we can highly value although predicated on primitive roles. Such as innovation. In physics new patterns of how the world works.

In book a metaphor for time scales that defy human intuition … logarithmic (powers of 10) floors in Empire State building. 10th floor as Big Bang to date. Floor 11 Sun goes red giant. … (Levin: A time when there can be no thought anymore.)

A reverence that we are here and what we can do [despite the dark side], our moment on the cosmic time line.

Q&A: Einstein’s block universe? Greene: That was a classical world. Determinism vs. probabilistic world. That’s not what we mean by free will. Not whether in classical or quantum world, but is the universe lawful? …

Related posts

Defining a universe — how many constants?

Cosmological fact and fiction

Biggest thing in the universe?

Beyond the Milky Way — a game-changing discovery


[1] Example: > “Four amazing astronomical discoveries from ancient Greece” by Gareth Dorrian, Ian Whittaker (May 10, 2020, originally published at The Conversation).

Herodotus (484BC to 425BC)
Aristarchus of Samos (310BC to 230BC)
Eratosthenes (276BC to 195 BC)

[2] Regarding Wiki’s article on heat death of the universe (aka Big Chill or Big Freeze), the Controversies section is interesting. Even the phrase “entropy of the universe” may not make sense. And I’ve always wondered how the universe could be considered a closed system in equilibrium. And how does gravity add to the mix?

Max Planck wrote that the phrase “entropy of the universe” has no meaning because it admits of no accurate definition. More recently, Walter Grandy writes: “It is rather presumptuous to speak of the entropy of a universe about which we still understand so little, and we wonder how one might define thermodynamic entropy for a universe and its major constituents that have never been in equilibrium in their entire existence.” According to Tisza: “If an isolated system is not in equilibrium, we cannot associate an entropy with it.” Buchdahl writes of “the entirely unjustifiable assumption that the universe can be treated as a closed thermodynamic system“.

[3] Amazon’s listing for Ernest Becker‘s book contains an excerpt. Here’s a quote from that excerpt.

It doesn’t matter whether the cultural hero-system is frankly magical, religious, and primitive or secular, scientific, and civilized. It is still a mythical hero-system in which people serve in order to earn a feeling of primary value, of cosmic specialness, of ultimate usefulness to creation, of unshakable meaning. They earn this feeling by carving out a place in nature, by building an edifice that reflects human value: a temple, a cathedral, a totem pole, a skyscraper, a family that spans three generations. The hope and belief is that the things that man creates in society are of lasting worth and meaning, that they outlive or outshine death and decay, that man and his products count. When Norman O. Brown said that Western society since Newton, no matter how scientific or secular it claims to be, is still as “religious” as any other, this is what he meant: “civilized” society is a hopeful belief and protest that science, money and goods make man count for more than any other animal. In this sense everything that man does is religious and heroic, and yet in danger of being fictitious and fallible.

4 thoughts on “A shelf life for the universe?

  1. Here’s an article from 2019 on the debate over the Big Bang theory – scenarios and models. A new prediction remains to be tested (observed) regarding the Big Bang’s inception – that, in the lead-up, characteristic “ripples” in the quantum fields are subtly preserved as detectable density variations.

    Daily Galaxy > “The Big Bang Signal –’That Could Kill the Theory’” (posted on Mar 26, 2019 in Science).

    In a paper that appeared in September of 2018 on the physics preprint site,, Loeb [an astrophysicist and cosmologist at Harvard University] and two Harvard colleagues, Xingang Chen and Zhong-Zhi Xianyu, … predicted an oscillatory pattern in the distribution of matter throughout the cosmos that, if detected, could distinguish between inflation and alternative scenarios — particularly the hypothesis that the Big Bang was actually a bounce preceded by a long period of contraction.

    The primordial universe was not entirely uniform. There were tiny irregularities in density on minuscule scales that became the seeds of the large-scale structure observed in today’s universe. This is the primary source of information physicists rely on to learn about what happened before the Big Bang. The ticks of the standard clock [any type of heavy elementary particle in the primordial universe] generated signals that were imprinted into the structure of those irregularities. Standard clocks in different theories of the primordial universe predict different patterns of signals, because the evolutionary histories of the universe are different.

    The team calculated how these standard clock signals should look in non-inflationary theories, and suggested how they should be searched for in astrophysical observations [for example, in the CMB or distribution of galaxies].

  2. And as to how our understanding of the universe has changed over recorded history, there’s an interesting bit about philosophy of science in this article, e.g., the influence of ancient Greek philosophy. The rabbit hole of ideal forms.

    Scientific research is based on the relationship between the reality of nature, as it is observed, and a representation of this reality, formulated by a theory in mathematical language. > “Einstein’s two mistakes” by François Vannucci, The Conversation (May 26, 2020).

    Einstein’s mistakes are summarized as:

    1. Fiddling with the cosmological constant – “I refuse to believe in a beginning of the universe.”

    2. Not accepting fundamental indeterminism in quantum mechanics – “I refuse to believe in chance.”

    But this philosophical riff was what interested me.

    At the beginning of the 20th century, people lived with the well-established idea of a static universe where the motion of stars never varies. This is probably due to Aristotle‘s teachings, stating that the sky is immutable, unlike Earth, which is perishable. This idea caused a historical anomaly: in 1054, the Chinese noticed the appearance of a new light in the sky, but no European document mentions it. Yet it could be seen in full daylight and lasted for several weeks. It was a supernova, that is, a dying star, the remnants of which can still be seen as the Crab Nebula. Predominant thought in Europe prevented people from accepting a phenomenon that so utterly contradicted the idea of an unchanging sky. A supernova is a very rare event, which can only be observed by the naked eye once a century. The most recent one dates back to 1987. So Aristotle was almost right in thinking that the sky was unchanging – on the scale of a human life at least.

  3. • YouTube > Fermilab > Don Lincoln > “23 Subatomic Stories: Dark energy and the fate of the universe” (Sept 9, 2020)

    Proposed 3 scenarios: Expand & crunch, Expand & stop, Expand & never stop. But what was discovered in 1998 was a 4th scenario: accelerating expansion.

    • YouTube > Fermilab > Don Lincoln > “24 Subatomic Stories: Where’s all the antimatter?” (Sept 16, 2020)

    Converting energy to matter always produces matter and anti-matter in equal quantities.

    (from transcript) Actually, when you convert energy, you convert it into equal amounts of matter and antimatter. Convert a photon, and you make an electron and antimatter electron, or quark and antiquark. That’s how it works, and it’s true for all kinds of energy. It’s also true that the two are always equal. The matter and antimatter are in identical amounts. That’s an experimental fact that scientists have confirmed again and again.

    In the Q&A re expansion rate, 5 billion years ago:

    (from transcript) But the changing speed of the expansion of the universe wasn’t some weird and arbitrary change. It has a clear explanation that should calm any fears of a spontaneous changing of physical laws.

    It comes down to a couple of things that are woven together. First, gravity by matter – ordinary or dark – is attractive. Second, gravity by dark energy is repulsive. Third, the density of dark energy is constant. And four, the universe is expanding. Those are the four important points.

    Shortly after the Big Bang, there was a fixed amount of total regular and dark matter in the universe. Dark energy was the same constant density it is now. The visible universe had a smaller volume. Multiplying density by volume gives total dark energy which is, of course, small due to the small volume of the universe. But, remember, the universe was expanding. The total amount of matter was constant, but the dark energy was increasing. At about five billion years ago, the amount of dark energy equaled the amount of matter. And, of course, over the last five billion years, the volume has increased more, leading to more dark energy. Since dark energy is a repulsive form of gravity, it was five billion years ago that repulsion overcame attraction and the expansion of the universe sped up. We see that five billion years ago wasn’t a time when dark energy “turned on,” so to speak. It just became dominant then.

  4. This topic is something that’s always given me pause, namely, that cosmologists view the universe as homogeneous (and isotropic) at large scales. How uniform? What scale is large enough? – when galaxies become cows? What, besides the CMB, contributes to that view? > “Gravity causes homogeneity of the universe” by Pia Gärtner, University of Vienna (September 24, 2020)

    Up to now, it was not clear whether the homogenization of the universe can be explained completely by Einstein’s equations.

    In the concrete problem, the time evolution of the originally strong deviations from the homogeneous state as cosmological gravitational waves has to be analyzed mathematically. It has to be shown that they decay in the course of the expansion thus allowing the universe to get its homogeneous structure.

    Until now, these [geometric] methods could only achieve such results for small deviations from the homogeneous space-time geometry. David Fajman from the University of Vienna has now succeeded for the first time to transfer these methods to the case of arbitrarily large deviations.

    The results published in the renowned journal PRL [Physical Review Letters] show that homogenization in the investigated class of models is already completely explained by Einstein’s theory and does not require any additional modifications. If this finding can be transferred to more general models, it means that it does not necessarily need a mechanism like inflation to explain the state of our present universe, but that Einstein’s theory could finally triumph once again.

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