Posts Tagged ‘Fred Hoyle’
“The universe is under no obligation to make sense to you”*…
Still, we try… In a consideration of three new books, the estimable Sean Carroll brings us up to date on the state of play…
Should scientists be embarrassed that they can’t settle on a definition for the Big Bang? The cosmologist Will Kinney describes it as the “physical theory of the hot infant universe,” while Wikipedia goes for the more elaborate “a physical theory that describes how the universe expanded from an initial state of high density and temperature.” The first refers only to early times, while the latter seems to extend to subsequent times as well. The physicist and science writer Tony Rothman offers the pithier “the universe’s origin,” the theoretical physicist Thomas Hertog suggests that it is the “primeval state” of cosmic history, and a NASA website gives us “the idea that the universe began as just a single point.” These seem to refer to one moment at the start of things, rather than the universe’s life since then.
All of these sources (except NASA, unfortunately) capture something correct. The confusion stems both from the inherent ambiguity of using ordinary language to describe novel scientific concepts and from the state of modern cosmology itself. Cosmology is the study of the universe on the largest scales. So it ignores details of stars and planets, focusing on galaxies and even bigger structures, up to the universe as a whole. Modern cosmology is only about a century old, as it wasn’t until the 1920s that astronomers determined that our own Milky Way is just one of a large number of galaxies and the origin and evolution of them all could be studied together. And it wasn’t until the 1990s that the field matured into the one that exists today, featuring precision measurements and ultralarge datasets.
Dealing as it does with some of the most profound questions about the nature of the cosmos, cosmological research has always involved a vigorous give-and-take between rampant speculation and unanticipated discoveries. Its practitioners have long been fond of spinning purportedly inviolate physical principles from their personal intuitions about how reality should work. But cosmology remains an empirical science—a cherished belief can be quickly swept away by a solid measurement.
The present moment in the science of cosmology is one of consolidation, as we have successfully incorporated the lessons of some impressive discoveries made near the turn of the twenty-first century. Yet crucially important questions remain unanswered, especially about what exactly happened at the onset of the expanding space that evolved into our contemporary universe. It is therefore a good time for books that take stock of where we are and what might come next, and that illustrate which puzzles modern physicists choose to take seriously.
This much we know: we live in a galaxy, the Milky Way, containing around 200 billion stars. There are something like a trillion galaxies in our observable universe, distributed almost uniformly through space. Stars and galaxies condensed out of an originally nearly smooth distribution of matter. Distant galaxies are moving apart from one another. Extrapolating backward, we reach a hot, densely packed configuration about 13.8 billion years ago. We can observe the remnants of this early period in nearly uniform cosmic background radiation coming from every direction in the sky.
The Big Bang model is precisely this general picture, of a universe that expands and cools out of a smooth, hot primordial state. It is well understood and almost universally accepted among modern cosmologists. The Big Bang event is a hypothetical moment when the whole thing might have started, at which the temperature and density are supposed to have been literally infinite—a “singularity,” in physics parlance. This is why the NASA definition above is unambiguously wrong: the Big Bang event has nothing to do with “a single point” in space—it refers to a moment in time.
Nobody knows whether there actually was such an event. To be honest, there probably wasn’t. Einstein’s theory of general relativity predicts that such a singularity would have happened, but most physicists think this signals a breakdown in the theory rather than being an accurate description of the physical world. A prediction of infinitely big physical quantities is apt to be a sign that we don’t have the right theoretical understanding…
[Starting with Einstein’s unification of space-time in 1905, Carroll explains the implications of quantum theory, in particular on the question of the expansion of the universe. Using the three (very different, but complementary) books under consideration, he unpacks the issues and demonstrates the way in which scientific theories about the origin of the universe often involve a vigorous give-and-take between speculation and discovery…]
… Taken together, these three books provide an illuminating view of the state of modern cosmology. There are established results, laudable efforts to connect promising hypotheses to a flood of incoming data, and brave speculations about the physical and metaphysical unknown. They are all notably well written for the genre and will keep readers entertained as they are educated. We can marvel at both how much scientists have learned about the universe and how much we have yet to understand.
The state of cosmology (and a look at science at work): “A First Time for Everything,” from @seanmcarroll.bsky.social in @nybooks.com.
* Neil deGrasse Tyson
###
As we wrestle with reality, we might spare a thought for a major (if, in the end, incorrect) character in tale that Carroll tells: Fred Hoyle; he died on this date in 2001. A prominent astronomer, he formulated the theory of stellar nucleosynthesis. But he is rather better remembered for his controversial stances on other scientific matters—in particular his rejection of the (as Carroll observes, now widely-accepted) “Big Bang” theory– a term he coined, derisively, in an episode of his immensely-popular series The Nature of the Universe on BBC radio– and his promotion of panspermia as the source of life on Earth (or maybe the traffic was in the other direction?).
“The commonality between science and art is in trying to see profoundly – to develop strategies of seeing and showing”*…
Working with her scientist husband, Orra Hitchcock produced illustrations on bolts of linen that manifest original knowledge about extinction, stratigraphy, and their evidentiary features in the surrounding landscape– and trained eager young students to recognize and describe geological and natural-historical phenomena…
After meeting and falling in love with Edward Hitchcock, her employer at Massachusetts’ Deerfield Academy, Orra (née White) married him in 1821, beginning a lifetime of professional collaboration while raising a family amid piles of rocks and research tomes. Highly trained, white, and wealthy, she was far from an oddity in nineteenth-century education. Like many other women of her class, Hitchcock received extensive instruction in the arts and sciences, making a name by working alongside, not beneath, a man who had easier access to academic opportunities. Variously lauded as “an anomaly” and “the most remarkable” of their era, her scientific illustrations have rarely been considered on their own terms — admired for the natural historical and religious knowledge they contain — without being made an exemplar of the broader category of “women’s work”.
Moving to Amherst when Edward was appointed Professor of Chemistry and Natural History, the couple embarked on a decades-long exploration of the Connecticut River Valley’s botany and geology. While Edward lectured to eager young students about the principles of nature, from the depths of oceans to the granite veins of the earth, Orra produced more than sixty hand-colored scientific illustrations on poster-sized linen swaths designed to be hung on classroom walls.
Ranging from extinct mammals like Megatherium (a genus of giant ground sloth [below]) through lithic strata to fossilized footprints, the collection is striking for its modern abstraction, anticipating the later works of George Maw. Although some of Hitchcock’s geological illustrations seem far from “accurate” in their specificity (or lack thereof), her devotion to clear and concise visual communication bespeaks a deep-seated understanding of complex scientific principles…
An appreciation: “Orra White Hitchcock’s Scientific Illustrations for the Classroom (1828–40),” from @PublicDomainRev.
* Edward Tufte
###
As we picture it, we might send sharply-observant birthday greetings to Cecilia Helena Payne-Gaposchkin; she was born on this date in 1900. An astrophysicist and astronomer, she was the first– in her Radcliffe (Harvard) PhD thesis in 1927– to apply the laws of atomic physics to the study of the temperature and density of stellar bodies: the first to conclude that hydrogen and helium are the two most common elements in the universe and the first to suggest that the Sun is primarily (99%) composed of hydrogen. During the 1920s, the accepted explanation of the Sun’s composition was a calculation of around 65% iron and 35% hydrogen. Her thesis adviser, astronomer Henry Norris Russell, reached a similar conclusion via his own observations several years later, and (while he made brief mention of Payne’s work) was for a time credited with the discovery. But in 1947, astronomer Fred Hoyle confirmed her original claim.
She spent her entire career at Harvard. In 1956 she became the first woman to be promoted to full professor from within the faculty at Harvard’s Faculty of Arts and Sciences. Later, with her appointment to the Chair of the Department of Astronomy, she also became the first woman to head a department at Harvard.
Her students included Helen Sawyer Hogg, Joseph Ashbrook, Paul W. Hodge, and Frank Drake (the creator of the Drake Equation)– all of whom made important contributions to astronomy.
“It is unnatural in a large field to have only one shaft of wheat, and in the infinite Universe only one living world”*…
NASA’s top scientists have a provocative message for the scientific community: that they need a plan in place for if — or when — we find evidence of extraterrestrial life…
James Green, the agency’s chief scientist, coauthored a new article, published in the journal Nature, urging researchers to create a framework for reporting evidence of aliens. In it, the authors stressed the importance of clearly communicating any findings of extraterrestrial life, as well as establishing clear expectations for the public for when it occurs and accurately expressing ambiguity in early evidence.
“As life-detection objectives become increasingly prominent in space sciences, it is essential to open a community dialogue about how to convey information in a subject matter that is diverse, complicated and has a high potential to be sensationalized,” read the paper.
Green and his co-authors propose a confidence of life detection (CoLD) scale to help evaluate any evidence that might be discovered. The scale itself contains seven different levels like a staircase. Each level is a benchmark that must be met before we can proceed to the next step.
For example, level one would be discovering life signatures such as biological molecules. The second level would be ruling out that the sign of life is the result of contamination from Earth. Eventually, the CoLD scale ends with the final step: scientists declaring that they’ve confidently discovered evidence of extraterrestrial life.
“Having a scale like this will help us understand where we are in terms of the search for life in particular locations, and in terms of the capabilities of missions and technologies that help us in that quest,” Green said in a NASA news release.
The paper’s authors stress that the scale is merely a starting point for a larger conversation with scientists and science communicators about the best ways to proceed if and when we discover evidence of alien life.
It also comes in the context of the upcoming launch of the powerful James Webb telescope, along with the Perseverance Mars rover searching for life on the Red Planet, meaning that such a finding might become a reality sooner rather than later.
“The search for life beyond Earth requires broad participation from the scientific community and many kinds of observations and experiments,” Mary Voltek, co-author of the study and head of NASA’s Astrobiology Program, said in the release. “Together, we can be stronger in our efforts to look for hints that we are not alone.”
“NASA Says We Need a Plan for When We Discover Alien Life,” from @futurism.
As to what we’ll do with that knowledge, a complicating factor: “94% of the universe’s galaxies are permanently beyond our reach” (if the speed of light remains an upper limit on travel).
###
As we search far and wide, we might send enduring birthday greetings to Sir Hermann Bondi; he was born on this date in 1919. A mathematician and cosmologist, he is best remembered for developing the steady state model of the universe with Fred Hoyle and Thomas Gold as an alternative to the Big Bang theory. In an attempt to explain the paradox: how can the stars continually recede, yet without disappearing, they audaciously proposed an unproven hypothesis: that the universe has an eternal existence, with no beginning and without an end. Further, they argued, the universe is continuously expanding, maintaining a constant density by continually creating new matter from energy. Their model was rendered obsolete when, in 1965, Arno Penzias and Robert Wilson detected a background microwave radiation from all directions in space, as predicted by the “Big Bang” theory of creation that is now accepted. [See here for more on Penzias’ and Wilson’s discovery.)
Bondi also contributed to the theory of general relativity; was the first to analyze the inertial and gravitational interaction of negative mass; and the first to explicate correctly the nature of gravitational waves.
“I’m sure the universe is full of intelligent life. It’s just been too intelligent to come here.”*…
The Fermi paradox, named for physicist Enrico Fermi, is the apparent contradiction between the lack of evidence for extraterrestrial civilizations and various high estimates for their probability (e.g., some of the optimistic estimates for the Drake equation). Fermi wondered, “where are they?”
By way of context, Tim Urban in his wonderful Wait But Why?:
As many stars as there are in our galaxy (100 – 400 billion), there are roughly an equal number of galaxies in the observable universe—so for every star in the colossal Milky Way, there’s a whole galaxy out there. All together, that comes out to the typically quoted range of between 1022 and 1024 total stars, which means that for every grain of sand on every beach on Earth, there are 10,000 stars out there.
The science world isn’t in total agreement about what percentage of those stars are “sun-like” (similar in size, temperature, and luminosity)—opinions typically range from 5% to 20%. Going with the most conservative side of that (5%), and the lower end for the number of total stars (1022), gives us 500 quintillion, or 500 billion billion sun-like stars.
There’s also a debate over what percentage of those sun-like stars might be orbited by an Earth-like planet (one with similar temperature conditions that could have liquid water and potentially support life similar to that on Earth). Some say it’s as high as 50%, but let’s go with the more conservative 22% that came out of a recent PNAS study. That suggests that there’s a potentially-habitable Earth-like planet orbiting at least 1% of the total stars in the universe—a total of 100 billion billion Earth-like planets.
So there are 100 Earth-like planets for every grain of sand in the world. Think about that next time you’re on the beach.
Moving forward, we have no choice but to get completely speculative. Let’s imagine that after billions of years in existence, 1% of Earth-like planets develop life (if that’s true, every grain of sand would represent one planet with life on it). And imagine that on 1% of those planets, the life advances to an intelligent level like it did here on Earth. That would mean there were 10 quadrillion, or 10 million billion intelligent civilizations in the observable universe.
Moving back to just our galaxy, and doing the same math on the lowest estimate for stars in the Milky Way (100 billion), we’d estimate that there are 1 billion Earth-like planets and 100,000 intelligent civilizations in our galaxy.1
SETI (Search for Extraterrestrial Intelligence) is an organization dedicated to listening for signals from other intelligent life. If we’re right that there are 100,000 or more intelligent civilizations in our galaxy, and even a fraction of them are sending out radio waves or laser beams or other modes of attempting to contact others, shouldn’t SETI’s satellite dish array pick up all kinds of signals?
But it hasn’t. Not one. Ever…
Perhaps. as we’ve mused here at (R)D before, life is there, but we’re not seeing it because it isn’t a form of life that we recognize: c.f., “Two possibilities exist: Either we are alone in the Universe or we are not. Both are equally terrifying” and “That is a very Earthling question to ask, Mr. Pilgrim.”
But there are some who’ve refused to give up on the search for more traditionally-defined life; indeed, a new study quantifies the “fraction” (to which Urban alludes, above) of civilizations that could (should?) be communicating around our galaxy:
One of the biggest and longest-standing questions in the history of human thought is whether there are other intelligent life forms within our Universe. Obtaining good estimates of the number of possible extraterrestrial civilizations has however been very challenging.
A new study led by the University of Nottingham and published [earlier this month] in The Astrophysical Journal has taken a new approach to this problem. Using the assumption that intelligent life forms on other planets in a similar way as it does on Earth, researchers have obtained an estimate for the number of intelligent communicating civilizations within our own galaxy -the Milky Way. They calculate that there could be over 30 active communicating intelligent civilizations in our home Galaxy…
Details at (the slightly misleadingly-titled): “Research sheds new light on intelligent life existing across the galaxy.”
* Arthur C. Clarke
###
As we stay tuned, we might send far-seeing birthday greeting to Fred Hoyle; he was born on this date in 1915. A prominent astronomer, he formulated the theory of stellar nucleosynthesis. But he is rather better remembered for his controversial stances on other scientific matters—in particular his rejection of the “Big Bang” theory (a term he coined, derisively, in one of his immensely-popular series The Nature of the Universe on BBC radio) and his promotion of panspermia as the source of life on Earth.
You must be logged in to post a comment.