Astronomers combine mathematical models with observations to develop workable theories of how the Universe came to be. The mathematical underpinnings of the Big Bang theory include Albert Einstein's general theory of relativity along with standard theories of fundamental particles.
Today NASA spacecraft such as the Hubble Space Telescope and the Spitzer Space Telescope continue measuring the expansion of the Universe.
One of the goals has long been to decide whether the Universe will expand forever, or whether it will someday stop, turn around, and collapse in a “Big Crunch?”
According to the theories of physics, if we were to look at the Universe one second after the Big Bang, what we would see is a 10-billion degree sea of neutrons, protons, electrons, anti-electrons (positrons), photons, and neutrinos.
Then, as time went on, we would see the Universe cool, the neutrons either decaying into protons and electrons or combining with protons to make deuterium (an isotope of hydrogen). As it continued to cool, it would eventually reach the temperature where electrons combined with nuclei to form neutral atoms.
Before this “recombination” occurred, the Universe would have been opaque because the free electrons would have caused light (photons) to scatter the way sunlight scatters from the water droplets in clouds. But when the free electrons were absorbed to form neutral atoms, the Universe suddenly became transparent.
Those same photons – the afterglow of the Big Bang known as cosmic background radiation – can be observed today.
Missions Study Cosmic Background Radiation
NASA has launched two missions to study the cosmic background radiation, taking “baby pictures” of the Universe only 400,000 years after it was born. The first of these was the Cosmic Background Explorer (COBE).
In 1992, the COBE team announced that they had mapped the primordial hot and cold spots in cosmic background radiation. These spots are related to the gravitational field in the early Universe and form the seeds of the giant clusters of galaxies that stretch hundreds of millions of light years across the Universe.
This work earned NASA's Dr. John C. Mather and George F. Smoot of the University of California the 2006 Nobel Prize for Physics.
The second mission to examine the cosmic background radiation was the Wilkinson Microware Anisotropy Probe (WMAP). With greatly improved resolution compared to COBE, WMAP surveyed the entire sky, measuring temperature differences of the microwave radiation that is nearly uniformly distributed across the Universe.
The picture shows a map of the sky, with hot regions in red and cooler regions in blue. By combining this evidence with theoretical models of the Universe, scientists have concluded that the Universe is “flat,” meaning that, on cosmological scales, the geometry of space satisfies the rules of Euclidean geometry (e.g.
, parallel lines never meet, the ratio of circle circumference to diameter is pi, etc).
A third mission, Planck, led by the European Space Agency with significant participation from NASA, was. launched in 2009. Planck is making the most accurate maps of the microwave background radiation yet.
With instruments sensitive to temperature variations of a few millionths of a degree, and mapping the full sky over 9 wavelength bands, it measures the fluctuations of the temperature of the CMB with an accuracy set by fundamental astrophysical limits.
The Universe's “baby picture”. WMAP's map of the temperature of the microwave background radiation shows tiny variations (of few microdegrees) in The 3K background. Hot spots show as red, cold spots as dark blue.
One problem that arose from the original COBE results, and that persists with the higher-resolution WMAP data, was that the Universe was too homogeneous.
How could pieces of the Universe that had never been in contact with each other have come to equilibrium at the very same temperature? This and other cosmological problems could be solved, however, if there had been a very short period immediately after the Big Bang where the Universe experienced an incredible burst of expansion called “inflation.
” For this inflation to have taken place, the Universe at the time of the Big Bang must have been filled with an unstable form of energy whose nature is not yet known. Whatever its nature, the inflationary model predicts that this primordial energy would have been unevenly distributed in space due to a kind of quantum noise that arose when the Universe was extremely small.
This pattern would have been transferred to the matter of the Universe and would show up in the photons that began streaming away freely at the moment of recombination. As a result, we would expect to see, and do see, this kind of pattern in the COBE and WMAP pictures of the Universe.
But all this leaves unanswered the question of what powered inflation. One difficulty in answering this question is that inflation was over well before recombination, and so the opacity of the Universe before recombination is, in effect, a curtain drawn over those interesting very early events.
Fortunately, there is a way to observe the Universe that does not involve photons at all. Gravitational waves, the only known form of information that can reach us undistorted from the instant of the Big Bang, can carry information that we can get no other way.
Several missions are being considered by NASA and ESA that will look for the gravitational waves from the epoch of inflation.
Big Bang theory wrong? Star older than Universe discovered – threat of ‘scientific crisis’
The Universe is thought to have popped into existence some 13.8 billion years ago when an infinitesimal point expanded in just a fraction of a second.
The Big Bang theory has stood for the best part of 100 years after Belgian physicist Georges Lemaître first proposed in 1927 the expansion of the Universe could be traced back to a single point.
However, the well-accepted model is now under the microscope after a team of researchers found a star which appears to be older than the cosmos.
A star know as “Methuselah star”, or scientifically called HD 140283, is situated about 200 lightyears away and has stumped experts.
Analysis of the star showed that it contained very little iron content, which would suggest that it formed during a period when the iron element was not abundant in the Universe.
This in turn led to the discovery the star is 14.5 billion years old, some 0.7 billion years older than the Universe.
Experts met at a conference in California in July in an attempt to solve the mystery, but so far questions have just led to more questions – and it could lead to a “scientific revolution”.
Big Bang theory wrong? Star older than Universe discovered – threat of ‘scientific crisis’ (Image: GETTY)
“Methuselah star”, or scientifically called HD 140283 (Image: NASA)
- British physicist Robert Matthews wrote for UAE-based media outlet The National: “It’s a riddle of cosmic proportions: How can the universe contain stars older than itself?
- “That’s the conundrum now facing astronomers trying to establish the age of the universe — and its resolution could spark a scientific revolution.
- “Astronomers now know it contains very little iron — which means it must have been formed before this element became common in the universe.
- “And that implies HD 140283 must be almost as old as the universe itself.”
- READ MORE: Alien discovery: Scientists narrow search after shocking find
Physics Nobel awarded for Big Bang-related theory and exoplanet discovery
US scientist James Peebles and Swiss scientists Michael Mayor and Didier Queloz are recipients of the prize for 2019
- An American scientist has been awarded this year’s Nobel Prize for Physics for his theory related to the Big Bang theory along with two Swiss scientists for their discovery of a planet outside the solar system, according to the Nobel Prize website.
- James Peebles from the United States and Michel Mayor and Didier Queloz from Switzerland are the joint recipients of the prestigious prize.
- “This year’s Nobel Prize in Physics rewards new understanding of the universe’s structure and history, and the first discovery of a planet orbiting a solar-type star outside our solar system,” the press statement on the website read.
- Peebles was awarded for his theory on what happened after the Big Bang took place nearly 14 billion years ago.
“The Big Bang model describes the universe from its very first moments, almost 14 billion years ago, when it was extremely hot and dense. Since then, the universe has been expanding, becoming larger and colder,” the statement read.
It added that 400,000 years after the Big Bang, the universe had become transparent and light rays were able to travel through space. “Even today, this ancient radiation is all around us and, coded into it, many of the universe’s secrets are hiding,” it noted.
“Using his theoretical tools and calculations developed since the mid-1960s, James Peebles was able to interpret these traces from the infancy of the universe and discover new physical processes,” it added.
Peebles’ results showed a universe to humanity in which just five per cent of the content was known. Finding out the mysteries behind the remaining 95 per cent was a challenge to modern physics, said the statement.
- On the other hand, in October 1995, Michel Mayor and Didier Queloz had announced the first discovery of a planet outside the solar system,
- The discovery of the planet ‘51 Pegasi b’ from the Haute-Provence Observatory in southern France, ‘started a revolution in astronomy and over 4,000 exoplanets have since been found in the Milky Way’.
- These discoveries challenged the world’s preconceived ideas about planetary systems and building up on them in the future might just help answer humanity’s eternal quest about whether life exists outside of the earth and the solar system, the statement noted.
We are a voice to you; you have been a support to us. Together we build journalism that is independent, credible and fearless. You can further help us by making a donation. This will mean a lot for our ability to bring you news, perspectives and analysis from the ground so that we can make change together.
India Environment Portal Resources :
What Astronomers Are Still Discovering About the Big Bang Theory
On a bright spring morning 50 years ago, two young astronomers at Bell Laboratories were tuning a 20-foot, horn-shaped antenna pointed toward the sky over New Jersey. Their goal was to measure the Milky Way galaxy, home to planet Earth.
To their puzzlement, Robert W. Wilson and Arno A. Penzias heard the insistent hiss of radio signals coming from every direction—and from beyond the Milky Way.
It took a full year of testing, experimenting and calculating for them and another group of researchers at Princeton to explain the phenomenon: It was cosmic microwave background radiation, a residue of the primordial explosion of energy and matter that suddenly gave rise to the universe some 13.
8 billion years ago. The scientists had found evidence that would confirm the Big Bang theory, first proposed by Georges Lemaître in 1931.
“Until then, some cosmologists believed that the universe was in a steady state without a singular beginning,” says Wilson, now 78 and a senior scientist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. “The finding helped rule that out.”
That assessment seems a bit modest for a discovery that received the Nobel Prize in Physics in 1978 and is now, on its semicentennial, celebrated as the Rosetta stone of modern cosmology, the key that has allowed generations of scientists to parse the origins of the universe.
Avi Loeb was a toddler on a farm in Israel when Wilson and Penzias began investigating those mysterious signals. Today, he’s a colleague of Wilson’s at the Center for Astrophysics and chair of Harvard’s astronomy department, and one of the world’s foremost researchers on what has been called the “cosmic dawn.
” The theoretical physicist, now 52, has published more than 450 papers on aspects of the early universe, including the formation of stars and galaxies and the origins of the first black holes.
He has done pioneering work on the three-dimensional mapping of the universe, and he has explored the implications of the impending collision between the Milky Way and the Andromeda galaxy (which will not happen, he adds, for several billion years).
Loeb recently made headlines with a paper submitted to the journal Astrobiology suggesting that just 15 million years after the Big Bang, the temperature from the cosmic background microwave radiation was 0 to 30 degrees Celsius—warm enough, he says, to allow “liquid water to exist on the surface of planets, if any existed,” without the warmth of a star. “So life in the universe could have started then.” By contrast, the earliest evidence of life on Earth is only 3.5 billion years old. Loeb’s proposition would add about ten billion years to the timeline of life in the universe.
“I’ve been trying to understand the beginning of the process before the Milky Way and its stars were formed,” he says. “It turns out that the first stars were more massive than the Sun and the first galaxies were smaller than the Milky Way.
” This period is compelling, he says, because “it is the scientific version of the story of Genesis. I don’t want to offend religious people, but the first chapter of the Bible needs revising—the sequence of events needs to be modified. It is true that there was a beginning in time.
As in the biblical story, ‘Let there be light.’ This light can be thought of as the cosmic microwave background.”
Loeb’s cherubic demeanor and puckish sense of humor play well on his YouTube videos, and Time and Popular Mechanics have cited his influence among space scientists. The title of his paper “How to Nurture Scientific Discoveries Despite Their Unpredictable Nature” reflects his appreciation of the accidental, such as the story behind the Wilson-Penzias discovery.
Recently, Wilson and Loeb have been working together on efforts to map the black hole at the center of the Milky Way. “I think Avi is a theorist who is very good at picking problems to work on that have testable results,” Wilson says.
Antimatter Discovery Reveals Clues about the Universe’s Beginning
In the beginning, there was matter and antimatter, and then there was only matter. Why? This question is one of the defining mysteries of physics. For decades theorists have come up with potential solutions, most involving the existence of extra particles beyond the known species in the universe.
Last week scientists announced tantalizing findings that point toward one possible solution, but the data fall short of a definitive discovery.
Whatever the final answer is, resolving the question may tell us more than just why we live in a universe of matter—it could expose secrets from the earliest epochs of the cosmos or even connect us to the invisible dark matter that eludes scientists.
Most of the theories about how matter got the upper hand over antimatter fall into two main camps. One, called electroweak baryogenesis, posits extra versions of the Higgs boson—the particle related to how everything else gets mass.
If these Higgs cousins exist, they could have helped set off an abrupt phase transition, akin to the shift when water goes from liquid to gas, early in the universe that might have led to slightly more matter than antimatter in space.
When matter and antimatter come into contact, they annihilate each other, so most of the stuff in the young universe would have been destroyed, leaving behind just a small surplus of matter to make the galaxies and stars and planets around us.
The other leading theory, called leptogenesis, stems instead from neutrinos. These particles are much, much lighter than quarks and pass through the cosmos ethereally, rarely stopping to interact with anything at all.
According to this scenario, in addition to the regular neutrinos we know of, there are extremely heavy neutrinos that are so gargantuan that they could have been forged only from the tremendous energies and temperatures present just after the big bang, when the universe was very hot and dense.
When these particles inevitably broke down into smaller, more stable species, the thinking goes, they might have produced slightly more matter than antimatter by-products, leading to the arrangement we see today.
Two Mysteries for the Price of One
The recent announcement, which was made by scientists at the T2K (Tokai to Kamioka) experiment in Japan, offers hopeful signs for the leptogenesis concept. The experiment observes neutrinos as they travel through 300 kilometers underground and change between three types, or flavors—a peculiar ability of neutrinos called oscillation.
The T2K researchers detected more oscillations in neutrinos than in antineutrinos, suggesting the two do not just act as mirror images of each other but, in fact, behave differently. Such a difference between a particle and its antimatter counterpart is termed CP violation, and it is a strong clue in the quest to understand how matter outran antimatter after the universe was born.
“We don’t call it a discovery yet,” says T2K team member Chang Kee Jung of Stony Brook University. The experiment has now ruled out the possibility that neutrinos have zero CP violation with 95 percent confidence, and it shows hints that the particles might display the maximum possible amount of CP violation allowed.
Yet more data, and probably future experiments, will be needed to precisely measure just how much neutrinos and antineutrinos differ.
Even if physicists make a definitive discovery of CP violation in neutrinos, they will not have completely solved the cosmic antimatter question.
Such a finding would be “necessary but not sufficient” to prove leptogenesis, says Seyda Ipek, a theoretical physicist at the University of California, Irvine. Another requirement of the theory is that neutrinos and antineutrinos turn out to be the same thing.
How is that seeming contradiction possible? Matter and antimatter are thought to be identical except for a reversed electrical charge. Neutrinos, having no charge, could be both at the same time.
If this possibility is the case, it could also explain why neutrinos are so light—perhaps less
Nobel Prize in Physics for two breakthroughs: Evidence for the Big Bang and a way to find exoplanets
Did the universe really begin with a Big Bang? And if so, is there evidence? Are there planets around other stars? Can they support life?
The 2019 Nobel Prize in Physics goes to three scientists who have provided deep insights into all of these questions.
James Peebles, an emeritus professor of physics at Princeton University, won half the prize for a body of work he completed since the 1960s, when he and a team of physicists at Princeton attempted to detect the remnant radiation of the dense, hot ball of gas at the beginning of the universe: the Bang Bang.
The other half went to Michel Mayor, an emeritus professor of physics from the University of Geneva, together with Didier Queloz, also a Swiss astrophysicist at the University of Geneva and the University of Cambridge. Both made breakthroughs with the discovery of the first planets orbiting other stars, also known as exoplanets, beyond our solar system.
I am an astrophysicist and was delighted to hear of this year’s Nobel recipients, who had a profound impact on scientists’ understanding of the universe. A lot of my own work on exploding stars is guided by theories describing the structure of the universe that James Peebles himself laid down.
In fact, one might say that Peebles, of all this year’s Nobel winners, is the biggest star of the real “Big Bang Theory.”
Nobel Prize winners in physics, from left, James Peebles in Princeton, N.J., Didier Queloz in London and Michel Mayor in Madrid. AP Photo/Frank Augstein
The real Big Bang Theory
As Peebles and his Princeton team rushed to complete their discovery in 1964, they were scooped by two young scientists at nearby Bell Labs, Arno Penzias and Robert Wilson. The remaining radiation from the Big Bang was predicted to be microwave energy, in much the same form used by countertop ovens.
What happened before the Big Bang?
In the beginning, there was an infinitely dense, tiny ball of matter. Then, it all went bang, giving rise to the atoms, molecules, stars and galaxies we see today.
Or at least, that's what we've been told by physicists for the past several decades.
But new theoretical physics research has recently revealed a possible window into the very early universe, showing that it may not be “very early” after all. Instead it may be just the latest iteration of a bang-bounce cycle that has been going on for … well, at least once, and possibly forever.
Of course, before physicists decide to toss out the Big Bang in favor of a bang-bounce cycle, these theoretical predictions will need to survive an onslaught of observation tests.
Scientists have a really good picture of the very early universe, something we know and love as the Big Bang theory. In this model, a long time ago the universe was far smaller, far hotter and far denser than it is today. In that early inferno 13.8 billion years ago, all the elements that make us what we are were formed in the span of about a dozen minutes.
Even earlier, this thinking goes, at some point our entire universe — all the stars, all the galaxies, all the everything — was the size of a peach and had a temperature of over a quadrillion degrees.
Amazingly, this fantastical story holds up to all current observations. Astronomers have done everything from observing the leftover electromagnetic radiation from the young universe to measuring the abundance of the lightest elements and found that they all line up with what the Big Bang predicts. As far as we can tell, this is an accurate portrait of our early universe.
- But as good as it is, we know that the Big Bang picture is not complete — there's a puzzle piece missing, and that piece is the earliest moments of the universe itself.
- That's a pretty big piece.
- Related: From Big Bang to present: Snapshots of our universe through time
The problem is that the physics that we use to understand the early universe (a wonderfully complicated mishmash of general relativity and high-energy particle physics) can take us only so far before breaking down. As we try to push deeper and deeper into the first moments of our cosmos, the math gets harder and harder to solve, all the way to the point where it just … quits.
The main sign that we have terrain yet to be explored is the presence of a “singularity,” or a point of infinite density, at the beginning of the Big Bang.
Taken at face value, this tells us that at one point, the universe was crammed into an infinitely tiny, infinitely dense point.
This is obviously absurd, and what it really tells us is that we need new physics to solve this problem — our current toolkit just isn't good enough.
Related: 8 ways you can see Einstein's theory of relativity in real life
To save the day we need some new physics, something that is capable of handling gravity and the other forces, combined, at ultrahigh energies.
And that's exactly what string theory claims to be: a model of physics that is capable of handling gravity and the other forces, combined, at ultrahigh energies.
Which means that string theory claims it can explain the earliest moments of the universe.
One of the earliest string theory notions is the “ekpyrotic” universe, which comes from the Greek word for “conflagration,” or fire. In this scenario, what we know as the Big Bang was sparked by something else happening before it — the Big Bang was not a beginning, but one part of a larger process.
Extending the ekpyrotic concept has led to a theory, again motivated by string theory, called cyclic cosmology.
I suppose that, technically, the idea of the universe continually repeating itself is thousands of years old and predates physics, but string theory gave the idea firm mathematical grounding.
The cyclic universe goes about exactly as you might imagine, continually bouncing between big bangs and big crunches, potentially for eternity back in time and for eternity into the future.
Before the beginning
As cool as this sounds, early versions of the cyclic model had difficulty matching observations — which is a major deal when you're trying to do science and not just telling stories around the campfire.
The main hurdle was agreeing with our observations of the cosmic microwave background, the fossil light leftover from when the universe was only 380,000 years old. While we can't see directly past that wall of light, if you start theoretically tinkering with the physics of the infant cosmos, you affect that afterglow light pattern.
And so, it seemed that a cyclic universe was a neat but incorrect idea.
But the ekpyrotic torch has been kept lit over the years, and a paper published in January to the arXiv database has explored the wrinkles in the mathematics and uncovered some previously missed opportunities.
The physicists, Robert Brandenberger and Ziwei Wang of McGill University in Canada, found that in the moment of the “bounce,” when our universe shrinks to an incredibly small point and returns to a Big Bang state, it's possible to line everything up to get the proper observationally tested result.
In other words, the complicated (and, admittedly, poorly understood) physics of this critical epoch may indeed allow for a radically revised view of our time and place in the cosmos.
But to fully test this model, we'll have to wait for a new generation of cosmology experiments, so let's wait to break out the ekpyrotic champagne.
Paul M. Sutter is an astrophysicist at SUNY Stony Brook and the Flatiron Institute, host of Ask a Spaceman and Space Radio, and author of Your Place in the Universe.
Originally published on Live Science.
Remembering Big Bang Basher Fred Hoyle
The recent deaths of Freeman Dyson, Philip Anderson and Margaret Burbidge have stirred up memories of other giants of physics. I’m posting profiles of some of these characters in the hope that readers will find them interesting and relevant to current scientific controversies.
They might also provide a distraction from coronavirus coverage. Below is an edited version of a portrait of Fred Hoyle, the iconoclastic British astrophysicist, who collaborated with Burbidge, from my 1996 book The End of Science. I interviewed Hoyle in 1992 at his home in England.
– John Horgan
A selective reading of Fred Hoyle's resume might make him appear to be the quintessential scientific insider. Born in 1915, Hoyle studied at the University of Cambridge under physicist and Nobel laureate Paul Dirac.
Their partnership worked well, Hoyle once said, since he didn't want a mentor and Dirac didn't want to be one.
Hoyle became a lecturer at Cambridge himself in 1945, and he swiftly moved to the forefront of astronomy, showing how nuclear physics could illuminate such celestial phenomena as white dwarfs, red giants, supernovae and the brilliant radio sources that came to be called quasars.
In 1953 Hoyle's investigations of how stars generate heavy elements led him to predict the existence of a previously unknown state of the isotope carbon 12. Shortly thereafter, the physicist William Fowler performed experiments that confirmed Hoyle's prediction.
Hoyle's work on stellar nucleosynthesis culminated in a 1957 paper, written with Fowler and Geoffrey and Margaret Burbidge, that remains a milestone in modern astrophysics.
Even Hoyle's critics think he deserved to share the Nobel Prize that Fowler received in 1983 for this research.
Hoyle founded the prestigious Institute of Astronomy at Cambridge in the early 1960's and served as its first director. For these and other achievements he was knighted in 1972. Yes, Hoyle is Sir Fred. Yet Hoyle's stubborn refusal to accept the big bang theory–and his adherence to fringe ideas in other fields–made him an outlaw in the field he had helped to create.
Since 1988, Hoyle has lived in a high-rise apartment building in Bournemouth, a town on England's southern coast.
When I visited him there in 1992, his wife Barbara let me in and took me into the living room, where I found Hoyle sitting in a chair watching a cricket match on television. He rose and shook my hand without taking his eyes off the match.
His wife, gently admonishing him for his rudeness, went over to the TV and turned it off. Only then did Hoyle, as if waking from a spell, turn his full attention to me.
I expected him to be odd and embittered, as many mavericks are, but he was, for the most part, quite amiable. With his pug nose, jutting jaw and penchant for slang–colleagues were “chaps” and a bad theory was a “bust flush”–he exuded a kind of blue-collar integrity and geniality. He reveled in the role of outsider.
“When I was young the old regarded me as an outrageous young fellow, and now that I'm old the young regard me as an outrageous old fellow.” He chuckled. “I should say that nothing would embarrass me more than if I were to be viewed as someone who is repeating what he has been saying year after year” as many astronomers do.
“What I would be worried about is somebody coming along and saying what you've been saying is technically not sound. That would worry me.”
Hoyle first started thinking seriously about the origin of the universe shortly after World War II during long conversations with physicists Thomas Gold and Herman Bondi.
“Bondi had a relative somewhere–he seemed to have relatives everywhere–and one sent him a case of rum,” Hoyle recalled.
While imbibing Bondi's booze, the three physicists turned to a perennial puzzle of the young and intoxicated: How did we come to be?
The finding that all galaxies in the cosmos are receding from one another had convinced many astronomers that the universe had exploded into being at a specific time in the past and was still expanding. Hoyle’s fundamental objection to this model was philosophical.
It did not make sense to talk about the creation of the universe unless one already had space and time for the universe to be created in. “You lose the universality of the laws of physics,” Hoyle explained to me. “Physics is no longer.
” The only alternative to this absurdity, Hoyle decided, was that space and time must have always existed.
He, Gold and Bondi thus invented the steady state theory, which posited that the universe is infinite both in space and time and constantly generates new matter through some still-unknown mechanism.
Hoyle stopped promoting the steady-state theory after the discovery of the microwave background radiation in the early 1960's seemed to provide conclusive evidence for the big bang. Theorists had predicted that the big bang would produce a microwave afterglow.
But his old doubts resurfaced in the 1980's as he watched cosmologists struggle to explain the formation of galaxies and other puzzles.
“I began to get the sense that there was something seriously wrong,” not only with these new concepts, he said, but with the big bang itself. “I'm a great believer that if you have a correct theory, you show a lot of positive results.
It seems to me that they'd gone on for 20 years, by 1985, and there wasn't much to show for it. And that couldn't be the case if it was right.”
Putting the “bang” in the Big Bang
As the Big Bang theory goes, somewhere around 13.8 billion years ago the universe exploded into being, as an infinitely small, compact fireball of matter that cooled as it expanded, triggering reactions that cooked up the first stars and galaxies, and all the forms of matter that we see (and are) today.
Just before the Big Bang launched the universe onto its ever-expanding course, physicists believe, there was another, more explosive phase of the early universe at play: cosmic inflation, which lasted less than a trillionth of a second. During this period, matter — a cold, homogeneous goop — inflated exponentially quickly before processes of the Big Bang took over to more slowly expand and diversify the infant universe.
Recent observations have independently supported theories for both the Big Bang and cosmic inflation. But the two processes are so radically different from each other that scientists have struggled to conceive of how one followed the other.
Now physicists at MIT, Kenyon College, and elsewhere have simulated in detail an intermediary phase of the early universe that may have bridged cosmic inflation with the Big Bang.
This phase, known as “reheating,” occurred at the end of cosmic inflation and involved processes that wrestled inflation’s cold, uniform matter into the ultrahot, complex soup that was in place at the start of the Big Bang.
“The postinflation reheating period sets up the conditions for the Big Bang, and in some sense puts the ‘bang’ in the Big Bang,” says David Kaiser, the Germeshausen Professor of the History of Science and professor of physics at MIT. “It’s this bridge period where all hell breaks loose and matter behaves in anything but a simple way.”
Kaiser and his colleagues simulated in detail how multiple forms of matter would have interacted during this chaotic period at the end of inflation.
Their simulations show that the extreme energy that drove inflation could have been redistributed just as quickly, within an even smaller fraction of a second, and in a way that produced conditions that would have been required for the start of the Big Bang.
The team found this extreme transformation would have been even faster and more efficient if quantum effects modified the way that matter responded to gravity at very high energies, deviating from the way Einstein’s theory of general relativity predicts matter and gravity should interact.
“This enables us to tell an unbroken story, from inflation to the postinflation period, to the Big Bang and beyond,” Kaiser says. “We can trace a continuous set of processes, all with known physics, to say this is one plausible way in which the universe came to look the way we see it today.”
The team’s results appear today in Physical Review Letters. Kaiser’s co-authors are lead author Rachel Nguyen, and John T. Giblin, both of Kenyon College, and former MIT graduate student Evangelos Sfakianakis and Jorinde van de Vis, both of Leiden University in the Netherlands.
“In sync with itself”