In the last few months, I’ve been struck by how many articles have been published in the popular media and science news about black holes and the Big Bang. Mainstream physics and science communications (like phys.org, quantamagazine.org, etc) lately seem to be discussing more and more “mind blowing” geometries of the universe (or multiverse, eh).
Of course, the topic of black holes always has been glamorous, a darling of the media and a touchstone of physics . Lots more articles on the massive black hole at the center of our very own galaxy. Lots more speculation about interactions near black holes. Merging of black holes , wandering black holes, white holes, etc. The reality and fiction of singularities.
The discovery of gravity waves by LIGO (as well as marketing of big science) may have broadened the appeal of massive cosmological events. Newsworthiness.
As for the Big Bang, there’s been more speculation about the character (and language) of spacetime before and after that event. Mirror positive and negative universes arising from such an event . Multiverses of big bangs. The rise and end of the universe.
There is the challenge of what makes for good stories, whether to popularize science or serve some pseudoscientific agenda. The film and TV industry has long loosely used glamorous aspects of science as dramatic plot elements. Stereotypes and tropes abound, as noted in this Scientific American blog post: “Hollywood’s Portrayals of Science and Scientists Are Ridiculous“ (January 15, 2019). 
But for scientists and science communicators there’s also the challenge of what the physics really says versus the hype, speculation, and claims of both story tellers and scientists (physicists). The science versus commentary about the science. Consensus versus open topics of active research. What makes for an interesting interview may stretch theory or become more about personality than the facts.
Quantum physics is indeed weird, but epistemic and ontic interpretations of quantum physics spawned bewildering tropes on the topic. The so-called Copenhagen interpretation and wave function multiverses, in particular, made for much artful fiction and pseudoscience. 
This distinction between ontic and epistemic viewpoints is the Big Divide for interpretations of quantum mechanics. It’s where you must reveal your true colours. Does the wavefunction express a limitation on what can be known about reality, or is it the only meaningful definition of reality at all? — Ball, Philip. Beyond Weird (p. 55). University of Chicago Press. Kindle Edition.
The same may be said for cosmology. In particular, for stories about the origin of the universe. Or whether terms like “origin” or “creation” even apply. And the limits of language to even discuss the topic. The entangled ‘verse … 10^n and 10^-n. So, where does that leave us regarding the big picture?
Well, that’s why Sean Carroll’s latest blog post caught my attention: “True Facts About Cosmology (or, Misconceptions Skewered)” (January 12, 2019). While I’m still unsure about his position on the multiverse, I admire his ongoing effort to clarify cosmological fact versus fiction, state of knowledge versus conjecture — defend against the “zone” being flooded with nonsense (to speak politely).
In his post, Carroll lists 19 talking points (below). (Bolding and ’s are mine.) Comments on his post are interesting also.
- The Big Bang model is simply the idea that our universe expanded and cooled from a hot, dense, earlier state. We have overwhelming evidence that it is true. [See Wiki …]
- The Big Bang event is not a point in space, but a moment in time: a singularity of infinite density and curvature. It is completely hypothetical, and probably not even strictly true. (It’s a classical prediction, ignoring quantum mechanics.)
- People sometimes also use “the Big Bang” as shorthand for “the hot, dense state approximately 14 billion years ago.” I do that all the time. That’s fine, as long as it’s clear what you’re referring to.
- The Big Bang might have been the beginning of the universe. Or it might not have been; there could have been space and time before the Big Bang. We don’t really know.
- Even if the BB was the beginning, the universe didn’t “pop into existence.” You can’t “pop” before time itself exists. It’s better to simply say “the Big Bang was the first moment of time.” (If it was, which we don’t know for sure.)
- The Borde-Guth-Vilenkin theorem says that, under some assumptions, spacetime had a singularity in the past. But it only refers to classical spacetime, so says nothing definitive about the real world.
- The universe did not come into existence “because the quantum vacuum is unstable.” It’s not clear that this particular “Why?” question has any answer, but that’s not it.
- If the universe did have an earliest moment, it doesn’t violate conservation of energy. When you take gravity into account, the total energy of any closed universe is exactly zero.
- The energy of non-gravitational “stuff” (particles, fields, etc.) is not conserved as the universe expands. You can try to balance the books by including gravity, but it’s not straightforward.
- The universe isn’t expanding “into” anything, as far as we know. General relativity describes the intrinsic geometry of spacetime, which can get bigger without anything outside.
- Inflation, the idea that the universe underwent super-accelerated expansion at early times, may or may not be correct; we don’t know. I’d give it a 50% chance, lower than many cosmologists but higher than some.
- The early universe had a low entropy. It looks like a thermal gas, but that’s only high-entropy if we ignore gravity. A truly high-entropy Big Bang would have been extremely lumpy, not smooth.
- Dark matter exists. Anisotropies in the cosmic microwave background establish beyond reasonable doubt the existence of a gravitational pull in a direction other than where ordinary matter is located.
- We haven’t directly detected dark matter yet, but most of our efforts have been focused on Weakly Interacting Massive Particles. There are many other candidates we don’t yet have the technology to look for. Patience.
- Dark energy may not exist; it’s conceivable that the acceleration of the universe is caused by modified gravity instead. But the dark-energy idea is simpler and a more natural fit to the data.
- Dark energy is not a new force; it’s a new substance. The force causing the universe to accelerate is gravity. 
- We have a perfectly good, and likely correct, idea of what dark energy might be: vacuum energy, a.k.a. the cosmological constant. An energy inherent in space itself. But we’re not sure.
- We don’t know why the vacuum energy is much smaller than naive estimates would predict. That’s a real puzzle.
- Neither dark matter nor dark energy are anything like the nineteenth-century idea of the aether.
Update April 3, 2020: YouTube > Fermilab > Don Lincoln > “What happened before the Big Bang?” (Mar 31, 2020)
 Ushma S. Neill, PhD, is vice president, Office of Scientific Education and Training, Memorial Sloan Kettering Cancer Center.
“Hello, I’m a scientist in a movie I know everything about theoretical physics, geology, astronomy, cosmology, history, biology, linguistics, oh yeah, also I’m a hacker.”
“Hello, I’m a scientist in a movie. You need the cure to a strange disease in 24 hours. I just so happen to be the best in my field. Everything works the first time I do it, and my knowledge spans through three different fields. Without extensive testing first, here’s your cure.”
Why are our noble professions thus portrayed when reality is more nuanced and varied? Is it so convenient to rely on old fashioned narratives and tropes that rarely coincide with the actual work done in labs and clinics …
Because attributing depth to scientists and giving full freight to the scientific process is not as handy, the way the public sees science is skewed.
 Much as the relationship between astronomy and astrology.
Astronomy has, as its most prominent pseudoscience, astrology—the discipline out of which it emerged. The pseudosciences sometimes intersect, compounding the confusion … — Sagan, Carl. The Demon-Haunted World: Science as a Candle in the Dark. Random House Publishing Group. Kindle Edition. Loc 799.
There’s a great deal of pseudoscience for the gullible on TV, a fair amount of, medicine and technology, but hardly any science—especially on the big commercial networks, whose executives tend to think that science programming means ratings declines and lost profits, and nothing else matters. There are network employees with the title “Science Correspondent,” and an occasional news feature said to be devoted to science. But we almost never hear any science from them, just medicine and technology.
When is the last time you heard an intelligent comment on science by a President of the United States? Why in all America is there no TV drama that has as its hero someone devoted to figuring out how the Universe works? — Ibid. Loc 5863.
Modern Roman Catholicism has no quarrel with the Big Bang, with a Universe 15 billion or so years old, with the first living things arising from prebiological molecules, or with humans evolving from apelike ancestors—although it has special opinions on “ensoulment.” Most mainstream Protestant and Jewish faiths take the same sturdy position. — Ibid. Loc 4442.
 Carroll clarified item #16:
Gravity causes the universe to accelerate because gravity is not always attractive. Roughly speaking, the “source of gravity” is the energy density of a fluid plus three times the pressure of that fluid. Ordinary substances have positive energy and pressure, so gravity attracts. But vacuum energy has negative pressure, equal in size but opposite in sign to its energy. So the net effect is to push things apart.
In the special case of vacuum energy, general relativity stipulates that the gravitational field is proportional to ρ + 3p (where ρ is the mass–energy density, and p is the pressure). Quantum theory of the vacuum further stipulates that the pressure of the zero-state vacuum energy is always negative and equal in magnitude to ρ. Thus, the total is ρ + 3p = ρ − 3ρ = −2ρ, a negative value. If indeed the vacuum ground state has non-zero energy, the calculation implies a repulsive gravitational field, giving rise to acceleration of the expansion of the universe, … However, the vacuum energy is mathematically infinite without renormalization, which is based on the assumption that we can only measure energy in a relative sense, which is not true if we can observe it indirectly via the cosmological constant.
 For example, this Space.com article, “A Mirror Image of Our Universe May Have Existed Before the Big Bang” (January 22, 2019):
Researchers Latham Boyle, Kieran Finn and Neil Turok at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, have turned this idea on its head by assuming the universe has always been fundamentally symmetrical and simple, then mathematically extrapolating into that first moment after the Big Bang.
“If someone can find a simpler version of the history of the universe than the existing one, then that’s a step forward. It doesn’t mean it’s right, but it means it’s worth looking at,” said Sean Carroll, a cosmologist at the California Institute of Technology who was cited in the paper but was not involved in the research. He pointed out that the current favorite candidate for dark matter — weakly interacting massive particles, or WIMPs — haven’t been found and it might be time to consider other options, including possibly the right-handed neutrinos Boyle mentioned. But, he said, he’s a long way from being persuaded and calls the paper “speculative.”
 Here’s an interesting visualization of the merger of 2 black holes on the Caltech YouTube channel: “Colliding and Wobbling Black Holes” (January 24, 2019).
 Here’s an excellent summary of the history of research regarding black holes on the Caltech YouTube channel (March 30, 2016) — a lecture by Kip Thorne from the General Relativity at One Hundred: The Sixth Biennial Francis Bacon Conference in March 2016. Wonderful visualizations. Background on the physics of the film Interstellar.
Note: Black hole solution with no matter …
20 thoughts on “Cosmological fact and fiction”
One of the seminal aspects of modern cosmology celebrates an anniversary this year, as noted in this Live Science article “The Day Edwin Hubble Realized Our Universe Was Expanding” (January 17, 2019).
An interesting question regarding the Big Bang and an expanding universe: “Does the Universe Have a Center?” (October 2, 2018).
As already noted regarding the expansion of the universe, there’s the raisins in rising dough analogy. This article also presents the balloon analogy and what the observable universe is.
And regarding the centers of galaxies, black holes evidently abound in the center of our Milky Way according to this NPR article: “Center of the Milky Way Has Thousands of Black Holes, Study Shows” (April 4, 2018).
Here’s an interesting Space.com article by Don Lincoln, Senior Scientist, Fermi National Accelerator Laboratory; Adjunct Professor of Physics, University of Notre Dame: “Did ‘The Big Bang Theory’ Get the Science Right? A Lesson in Supersymmetry and Economy Class” (January 24, 2019). He compares the physics portrayed in a recent episode of the hit television show “The Big Bang Theory” with real science.
Sean Carroll’s blog post “Intro to Cosmology Videos” (May 14, 2018) has links to CERN videos of lectures he gave there in 2005.
Here’s another take on the fact and fiction of black holes, an article in Quanta Magazine: “The Double Life of Black Holes” (January 29, 2019).
This YouTube video lecture (Int’l Centre for Theoretical Physics streamed live on Jan 28, 2019) by a well-known theoretical physicist (Juan Maldacena, Institute for Advanced Study, IAS, Princeton, USA) provides a useful background on research regarding black holes and the Big Bang: “Lecture 1: Quantum mechanics and the geometry of spacetime” (Salam Distinguished Lectures 2019).
One of the more interesting statements which I’d not encountered before was on this slide:
Black hole solution with no matter …
Key concept: Classical harmonic oscillator vs. quantized (QM) oscillator.
Coupling between harmonic oscillators — between bosons (in QFT) and matter (fermions) — and the geometry of spacetime.
Bosons and fermions (quarks, leptons).
Example: An electron is a lepton (fermion).
Wiki: A hadron is a composite particle made of two or more quarks held together by the strong force in a similar way as molecules are held together by the electromagnetic force. Most of the mass of ordinary matter comes from two hadrons, the proton and the neutron.
Analog models of gravity
Here’s another article on research about the Big Bang, published by Scientific American on February 6, 2019: “Have We Mismeasured the Universe?” Analysis of sound patterns in the CMB is another way to peg the cosmic distance ladder. Getting various models and observations to agree (closely enough) perhaps depends on reconsidering “how the universe behaved during its unseen initial 380,000 years.”
And here’s yet another Phys.org article on research which may settle the “expansion problem” and the Hubble constant: “Gravitational waves will settle cosmic conundrum” (published February 14, 2019).
And here’s another article by Ethan Siegel, Forbes Senior Contributor, on the question “This Is Why We Aren’t Expanding, Even If The Universe Is” (February 19, 2019).
As in his original January 12, 2019, blog post, Sean Carroll answers more questions about the Big Bang in this Live Science article “What Happened Before the Big Bang?” (April 17, 2019 ).
This Phys.org article “Variations in the ‘fogginess’ of the universe identify a milestone in cosmic history” by University of Cambridge (April 16, 2019) explores the timeline after the Big Bang: in particular, “when reionisation ended and the universe emerged from a cold and dark state to become what it is today: full of hot and ionised hydrogen gas permeating the space between luminous galaxies.”
Regarding the “cosmic distance ladder,” this Phys.org article recaps some recent research about the Hubble constant: “New Hubble measurements confirm universe is expanding faster than expected” by Johns Hopkins University (April 25, 2019).
The article includes two YouTube visualizations:
Animation of cosmic distance ladder — HubbleESA (uploaded on Sep 14, 2016) — This animation shows the principle of the cosmic distance ladder used by Adam Riess and his team to reduce the uncertainty of the Hubble constant.
Hubblecast 120 Light: Continued Discrepancy in the Universe’s Expansion Rate — HubbleESA (published on Apr 25, 2019 — Measurements of today’s expansion rate do not match the rate that was expected based on how the Universe appeared shortly after the Big Bang over 13 billion years ago. Using new data from the NASA/ESA Hubble Space Telescope, astronomers have significantly lowered the possibility that this discrepancy is a fluke.
This Phys.org article “New clues about how ancient galaxies lit up the universe” by Calla Cofield, Jet Propulsion Laboratory (May 9, 2019), covers ongoing research on “the Epoch of Reionization, a major cosmic event that transformed the universe from being mostly opaque to the brilliant starscape seen today.” The cosmic timeline …
See also this Science Alert article (May 9, 2019) “Strangely Bright Galaxies from the Early Universe Could Finally Explain a Cosmic Mystery.”
Or this Cnet article (May 8, 2019) “NASA telescope spies unusual galaxies from dawn of the universe — After staring at the sky for 200 hours, the Spitzer telescope spots 135 surprisingly bright galaxies from the early universe.”
This Phys.org article “Star formation burst in the Milky Way 2–3 billion years ago” by University of Barcelona (May 9, 2019) summarizes findings of analysis of “data from the Gaia satellite … that a heavy star formation burst occurred in the Milky Way about 3,000 million years ago. During this process, more than 50 percent of the stars that created the galactic disc may have been born. These results are derived from the combination of the distances, colors and magnitude of the stars that were measured by Gaia with models that predict their distribution in our galaxy. The study has been published in the journal Astronomy & Astrophysics.” Modeling and measurement …
“Did Time Have A Beginning? — When we think about the birth of the Universe, was time already in place?” by Ethan Siegel (Jun 14, 2019)
Terms: Big Bang, background microwave radiation, inflation, blackbody radiation, entropy, extapolation, asymptote, visible universe, dark matter, dark energy, singularity (where “both spatial and temporal dimensions cease to exist”), Paul Davies, tautology, observation vs. theory.
The “Big Bang” sounds like an explosive event, correct? Well, not so fast, eh.
Phys.org > “How could an explosive Big Bang be the birth of our universe?” by Michael Lam, The Conversation (May 1, 2020) – How can a Big Bang have been the start of the universe, since intense explosions destroy everything?
Is there any reason to question the Big Bang theory? Much in modern physics and cosmology is mind-boggling. Is being so contrary to our common sense cause for challenge? Despite being incomplete, this Forbes article (below) notes that any alternative narrative first needs to explain well-established facts and answer “how do we know …”
The outlook for any alternative theory is discussed in a new book The Cosmic Revolutionary’s Handbook: (Or: How to Beat the Big Bang) by two cosmologists and science communicators: Luke A. Barnes (a postdoctoral researcher at Western Sydney University) and Geraint F. Lewis (a Professor of Astrophysics at the Sydney Institute for Astronomy).
Forbes > “Is It Time To Dethrone The Big Bang Theory?” by Jamie Carter, Senior Contributor (May 14, 2020).
 [Teaser] Free yourself from cosmological tyranny! Everything started in a Big Bang? Invisible dark matter? Black holes? Why accept such a weird cosmos? For all those who wonder about this bizarre universe, and those who want to overthrow the Big Bang, this handbook gives you ‘just the facts’: the observations that have shaped these ideas and theories. While the Big Bang holds the attention of scientists, it isn’t perfect. The authors pull back the curtains, and show how cosmology really works. With this, you will know your enemy, cosmic revolutionary – arm yourself for the scientific arena where ideas must fight for survival! This uniquely-framed tour of modern cosmology gives a deeper understanding of the inner workings of this fascinating field. The portrait painted is realistic and raw, not idealized and airbrushed – it is science in all its messy detail, which doesn’t pretend to have all the answers.
Another recap of the Big Bang timeline (with some visualizations) … energy … initial seed fluctuations … a recipe of normal & dark matter and radiation … a behavioral model (physics) and stage (spacetime) for constraint (structure) … asymmetries … phase transitions … pre-inflation black box .
• Forbes > “Ask Ethan: How Did The Entire Universe Come From Nothing?” by Ethan Siegel, Senior Contributor (Nov 27, 2020)
Here’s a recap of problematical alternatives to the Big Bang theory. Any theory needs to agree with observational evidence: expansion, quasars, CMB, recession speed ∝ distance, accelerating expansion. And simplicity.
• Space.com > “5 failed alternatives to the Big Bang theory and why they didn’t work” by Paul Sutter (April 17, 2022) – “We live in a dynamic, evolving universe.”
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