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There are 5 eras in the universe's lifecycle. Right now, we're in the second era.
Astronomers find these five chapters to be a handy way of conceiving the universe's incredibly long lifespan.
- We're in the middle, or thereabouts, of the universe's Stelliferous era.
- If you think there's a lot going on out there now, the first era's drama makes things these days look pretty calm.
- Scientists attempt to understand the past and present by bringing together the last couple of centuries' major schools of thought.
If you're fortunate enough to get yourself beneath a clear sky in a dark place on a moonless night, a gorgeous space-scape of stars waits. If you have binoculars and point them upward, you're treated to a mind-bogglingly dense backdrop of countless specks of light absolutely everywhere, stacked atop each other, burrowing outward and backward through space and time. Such is the universe of the cosmological era in which we live. It's called the Stelliferous era, and there are four others.
The 5 eras of the universe
There are many ways to consider and discuss the past, present, and future of the universe, but one in particular has caught the fancy of many astronomers. First published in 1999 in their book The Five Ages of the Universe: Inside the Physics of Eternity, Fred Adams and Gregory Laughlin divided the universe's life story into five eras:
- Primordial era
- Stellferous era
- Degenerate era
- Black Hole Era
- Dark era
The book was last updated according to current scientific understandings in 2013.
It's worth noting that not everyone is a subscriber to the book's structure. Popular astrophysics writer Ethan C. Siegel, for example, published an article on Medium last June called "We Have Already Entered The Sixth And Final Era Of Our Universe." Nonetheless, many astronomers find the quintet a useful way of discuss such an extraordinarily vast amount of time.
The Primordial era
Image source: Sagittarius Production/Shutterstock
This is where the universe begins, though what came before it and where it came from are certainly still up for discussion. It begins at the Big Bang about 13.8 billion years ago.
For the first little, and we mean very little, bit of time, spacetime and the laws of physics are thought not yet to have existed. That weird, unknowable interval is the Planck Epoch that lasted for 10-44 seconds, or 10 million of a trillion of a trillion of a trillionth of a second. Much of what we currently believe about the Planck Epoch eras is theoretical, based largely on a hybrid of general-relativity and quantum theories called quantum gravity. And it's all subject to revision.
That having been said, within a second after the Big Bang finished Big Banging, inflation began, a sudden ballooning of the universe into 100 trillion trillion times its original size.
Within minutes, the plasma began cooling, and subatomic particles began to form and stick together. In the 20 minutes after the Big Bang, atoms started forming in the super-hot, fusion-fired universe. Cooling proceeded apace, leaving us with a universe containing mostly 75% hydrogen and 25% helium, similar to that we see in the Sun today. Electrons gobbled up photons, leaving the universe opaque.
About 380,000 years after the Big Bang, the universe had cooled enough that the first stable atoms capable of surviving began forming. With electrons thus occupied in atoms, photons were released as the background glow that astronomers detect today as cosmic background radiation.
Inflation is believed to have happened due to the remarkable overall consistency astronomers measure in cosmic background radiation. Astronomer Phil Plait suggests that inflation was like pulling on a bedsheet, suddenly pulling the universe's energy smooth. The smaller irregularities that survived eventually enlarged, pooling in denser areas of energy that served as seeds for star formation—their gravity pulled in dark matter and matter that eventually coalesced into the first stars.
The Stelliferous era
Image source: Casey Horner/unsplash
The era we know, the age of stars, in which most matter existing in the universe takes the form of stars and galaxies during this active period.
A star is formed when a gas pocket becomes denser and denser until it, and matter nearby, collapse in on itself, producing enough heat to trigger nuclear fusion in its core, the source of most of the universe's energy now. The first stars were immense, eventually exploding as supernovas, forming many more, smaller stars. These coalesced, thanks to gravity, into galaxies.
One axiom of the Stelliferous era is that the bigger the star, the more quickly it burns through its energy, and then dies, typically in just a couple of million years. Smaller stars that consume energy more slowly stay active longer. In any event, stars — and galaxies — are coming and going all the time in this era, burning out and colliding.
Scientists predict that our Milky Way galaxy, for example, will crash into and combine with the neighboring Andromeda galaxy in about 4 billion years to form a new one astronomers are calling the Milkomeda galaxy.
Our solar system may actually survive that merger, amazingly, but don't get too complacent. About a billion years later, the Sun will start running out of hydrogen and begin enlarging into its red giant phase, eventually subsuming Earth and its companions, before shrining down to a white dwarf star.
The Degenerate era
Image source: Diego Barucco/Shutterstock/Big Think
Next up is the Degenerate era, which will begin about 1 quintillion years after the Big Bang, and last until 1 duodecillion after it. This is the period during which the remains of stars we see today will dominate the universe. Were we to look up — we'll assuredly be outta here long before then — we'd see a much darker sky with just a handful of dim pinpoints of light remaining: white dwarfs, brown dwarfs, and neutron stars. These"degenerate stars" are much cooler and less light-emitting than what we see up there now. Occasionally, star corpses will pair off into orbital death spirals that result in a brief flash of energy as they collide, and their combined mass may become low-wattage stars that will last for a little while in cosmic-timescale terms. But mostly the skies will be be bereft of light in the visible spectrum.
During this era, small brown dwarfs will wind up holding most of the available hydrogen, and black holes will grow and grow and grow, fed on stellar remains. With so little hydrogen around for the formation of new stars, the universe will grow duller and duller, colder and colder.
And then the protons, having been around since the beginning of the universe will start dying off, dissolving matter, leaving behind a universe of subatomic particles, unclaimed radiation…and black holes.
The Black Hole era
Image source: Vadim Sadovski/Shutterstock/Big Think
For a considerable length of time, black holes will dominate the universe, pulling in what mass and energy still remain.
Eventually, though, black holes evaporate, albeit super-slowly, leaking small bits of their contents as they do. Plait estimates that a small black hole 50 times the mass of the sun would take about 1068 years to dissipate. A massive one? A 1 followed by 92 zeros.
When a black hole finally drips to its last drop, a small pop of light occurs letting out some of the only remaining energy in the universe. At that point, at 1092, the universe will be pretty much history, containing only low-energy, very weak subatomic particles and photons.
The Dark Era
Image source: Big Think
We can sum this up pretty easily. Lights out. Forever.
Tonight, if it's clear, maybe you want to step outside, take a nice deep breath, and look up, grateful that we are where we are, and when we are, in spite of all the day's hardships. We've got a serious amount of temporal elbow room here, far more than we need, so not to worry, and those stars aren't going anywhere for a long, long time.
Scientists use new methods to discover what's inside drug containers used by ancient Mayan people.
- Archaeologists used new methods to identify contents of Mayan drug containers.
- They were able to discover a non-tobacco plant that was mixed in by the smoking Mayans.
- The approach promises to open up new frontiers in the knowledge of substances ancient people consumed.
Ancient Mayans have been a continuing source of inspiration for their monuments, knowledge, and mysterious demise. Now a new study discovers some of the drugs they used. For the first time, scientists found remnants of a non-tobacco plant in Mayan drug containers. They believe their analysis methods can allow them exciting new ways of investigating the different types of psychoactive and non-psychoactive plants used by the Maya and other pre-Colombian societies.
The research was carried out by a team from Washington State University, led by anthropology postdoc Mario Zimmermann. They spotted residue of the Mexican marigold (Tagetes lucida) in 14 tiny ceramic vessels that were buried over a 1,000 years ago on Mexico's Yucatan peninsula. The containers also exhibited chemical traces of two types of tobacco: Nicotiana tabacum and N. rustica. Scientists think the marigold was mixed in with the tobacco to make the experience more pleasant.
"While it has been established that tobacco was commonly used throughout the Americas before and after contact, evidence of other plants used for medicinal or religious purposes has remained largely unexplored," said Zimmermann. "The analysis methods developed in collaboration between the Department of Anthropology and the Institute of Biological Chemistry give us the ability to investigate drug use in the ancient world like never before."
The scientists used a new method based on metabolomics that is able to pinpoint thousands of plant compounds, or metabolites, in residue of archaeological artifacts like containers and pipes. This allows the researchers to figure out which specific plants were utilized. The way plant residue was identified before employed looking for specific biomarkers from nicotine, caffeine, and other such substances. That approach would not be able to spot what else was consumed outside of what biomarker was found. The new way gives much more information, showing the researchers a fuller picture of what the ancient people ingested.
PARME staff archaeologists excavating a burial site at the Tamanache site, Mérida, Yucatan.
The containers in the study were found by Zimmerman and a team of archaeologists in 2012.
"When you find something really interesting like an intact container it gives you a sense of joy," shared Zimmermann. "Normally, you are lucky if you find a jade bead. There are literally tons of pottery sherds but complete vessels are scarce and offer a lot of interesting research potential."
The researchers are negotiating with various Mexican institutions to be able to study more ancient containers for plant residues. They also aim to look at organic materials possibly preserved in the dental plaque of ancient remains.
Check out the study published in Scientific Reports.
For some reason, the bodies of deceased monks stay "fresh" for a long time.
- The bodies of some Tibetan monks remain "fresh" after what appears to be their death.
- Their fellow monks say they're not dead yet but in a deep, final meditative state called "thukdam."
- Science has not found any evidence of lingering EEG activity after death in thukdam monks.
It's definitely happening, and it's definitely weird. After the apparent death of some monks, their bodies remain in a meditating position without decaying for an extraordinary length of time, often as long as two or three weeks.
Tibetan Buddhists, who view death as a process rather than an event, might assert that the spirit has not yet finished with the physical body. For them, thukdam begins with a "clear light" meditation that allows the mind to gradually unspool, eventually dissipating into a state of universal consciousness no longer attached to the body. Only at that time is the body free to die.
Whether you believe this or not, it is a fascinating phenomenon: the fact remains that their bodies don't decompose like other bodies. (There have been a handful of other unexplained instances of delayed decomposition elsewhere in the world.)
The scientific inquiry into just what is going on with thukdam has attracted the attention and support of the Dalai Lama, the highest monk in Tibetan Buddhism. He has reportedly been looking for scientists to solve the riddle for about 20 years. He is a supporter of science, writing, "Buddhism and science are not conflicting perspectives on the world, but rather differing approaches to the same end: seeking the truth."
The most serious study of the phenomenon so far is being undertaken by The Thukdam Project of the University of Wisconsin-Madison's Center for Healthy Minds. Neuroscientist Richard Davidson is one of the founders of the center and has published hundreds of articles about mindfulness.
Davidson first encountered thukdam after his Tibetan monk friend Geshe Lhundub Sopa died, officially on August 28, 2014. Davidson last saw him five days later: "There was absolutely no change. It was really quite remarkable."
The science so far
Credit: GrafiStart / Adobe Stock
The Thukdam Project published its first annual report this winter. It discussed a recent study in which electroencephalograms failed to detect any brain activity in 13 monks who had practiced thukdam and had been dead for at least 26 hours. Davidson was senior author of the study.
While some might be inclined to say, well, that's that, Davidson sees the research as just a first step on a longer road. Philosopher Evan Thompson, who is not involved in The Thukdam Project, tells Tricycle, "If the thinking was that thukdam is something we can measure in the brain, this study suggests that's not the right place to look."
In any event, the question remains: why are these apparently deceased monks so slow to begin decomposition? While environmental factors can slow or speed up the process a bit, usually decomposition begins about four minutes after death and becomes quite obvious over the course of the next day or so.
As the Dalai Lama said:
"What science finds to be nonexistent we should all accept as nonexistent, but what science merely does not find is a completely different matter. An example is consciousness itself. Although sentient beings, including humans, have experienced consciousness for centuries, we still do not know what consciousness actually is: its complete nature and how it functions."
As thukdam researchers continue to seek a signal of post-mortem consciousness of some sort, it's fair to ask what — and where — consciousness is in the first place. It is a question with which Big Think readers are familiar. We write about new theories all the time: consciousness happens on a quantum level; consciousness is everywhere.
So far, though, says Tibetan medical doctor Tawni Tidwell, also a Thukdam Project member, searches beyond the brain for signs of consciousness have gone nowhere. She is encouraged, however, that a number of Tibetan monks have come to the U.S. for medical knowledge that they can take home. When they arrive back in Tibet, she says, "It's not the Westerners who are doing the measuring and poking and prodding. It's the monastics who trained at Emory."
When Olympic athletes perform dazzling feats of athletic prowess, they are using the same principles of physics that gave birth to stars and planets.
- Much of the beauty of gymnastics comes from the physics principle called the conservation of angular momentum.
- Conservation of angular momentum tells us that when a spinning object changes how its matter is distributed, it changes its rate of spin.
- Conservation of angular momentum links the formation of planets in star-forming clouds to the beauty of a gymnast's spinning dismount from the uneven bars.
It is that time again when we watch in awe as Olympic athletes perform dazzling feats of athletic prowess. But as we stare in rapt attention at the speed, grace, and strength they exhibit, it is also a good time to pay attention to how they embody, literally, fundamental principles that shape the entire universe. Yes, I'm talking about physics. On our screens, these athletes are giving us lessons in the principles that giants like Isaac Newton struggled mightily to articulate.
Naturally, there are many Olympic events from which we could learn some basic principles of physics. Swimming shows us hydrodynamic drag. Boxing teaches us about force and impulse. (Ouch!) But today, we will focus on gymnastics and the cosmic importance of the conservation of angular momentum.
The conservation of angular momentum
Much of the beauty of gymnastics comes from the spins and flips athletes perform as they launch themselves into the air from the vault or uneven bars. These are all examples of rotations — and so much of the structure and history of the universe, from planets to galaxies, comes down to the physics of rotating objects. And so much of the physics of rotating objects comes down to the conservation of angular momentum.
Let's start with the conservation of regular or "linear" momentum. Momentum is the product of mass and velocity. Way back in the age of Galileo and Newton, physicists came to understand that in the interactions between bodies, the sum of their momentums had to be conserved (which really means "does not change"). This is a familiar idea to anyone who has played billiards: when a moving pool ball strikes a stationary one, the first ball stops while the second scoots away. The total momentum of the system (the mass times velocity of both balls taken together) is conserved, leaving the originally moving ball unmoving and the originally stationary ball carrying all the system's momentum.
Credit: Sergey Nivens and Victoria VIAR PRO via Adobe Stock
Rotating objects also obey a conservation law, but now it is not just the mass of an object that matters. The distribution of mass — that is, where the mass is located relative to the center of the rotation — is also a factor. Conservation of angular momentum tells us that if a spinning object is not subject to any forces, then any changes in how its matter is distributed must lead to a change in its rate of spin. Comparing the conservation of angular momentum to the conservation of linear momentum, the "distribution of mass" is analogous to mass, and the "rate of spin" is analogous to velocity.
There are many places in cosmic physics where this conservation of angular momentum is key. My favorite example is the formation of stars. Every star begins its life as a giant cloud of slowly spinning interstellar gas. The clouds are usually supported against their own gravitational weight by gas pressure, but sometimes a small nudge from, say, a passing supernova blast wave will force the cloud to begin gravitational collapse. As the cloud begins to shrink, the conservation of angular momentum forces the spin rate of material in the cloud to speed up. As material is falling inward, it also rotates around the cloud's center at ever higher rates. Eventually, some of that gas is going so fast that a balance between the gravity of the newly forming star and what is called centrifugal force is achieved. That stuff then stops moving inward and goes into orbit around the young star, forming a disk, some material of which eventually becomes planets. So, the conservation of angular momentum is, literally, why we have planets in the universe!
Gymnastics, a cosmic sport
How does this appear in gymnastics? When athletes hurl themselves into the air to perform a flip, the only force acting on them is gravity. But since gravity only affects their "center of mass," it cannot apply forces in a way that changes the athlete's spin. But the gymnasts can do that for themselves by using the conservation of angular momentum.
By changing how their mass is arranged, gymnasts can change how fast they spin. You can see this in the dismount phase of the uneven bar competitions. When a gymnast comes off the bars and performs a flip by tucking their legs inward, they can quickly increase their rotation rate in midair. The sudden dramatic increase in the speed of their flip is what makes us gasp in astonishment. It is both scary and a beautiful testament to the athletes' ability to intuitively control the physics of their bodies. And it is also the exact same physics that controls the birth of planets.
"As above so below," goes the old saying. You should keep that in mind as you watch the glory that is the Olympics. That is because it is not just athletes that have this intuitive understanding of physics. We all have it, and we use it every day, from walking down the stairs to swinging a hammer. So, it is no exaggeration to claim that the first place we came to understand the deepest principles of physics was not in contemplating the heavens but moving through the world in our own earthbound flesh.