Big Bang Archives

February 10, 2014March 8, 2017 by Fraser Cain

How Old is the Universe?

The Universe is vast bubble of space and time, expanding in volume. Run the clock backward and you get to a point where everything was compacted into a microscopic singularity of incomprehensible density. In a fraction of a second, it began expanding in volume, and it’s still continuing to do so today.

So how old is the Universe? How long has it been expanding for? How do we know? For a good long while, Astronomers assumed the Earth, and therefore the Universe was timeless. That it had always been here, and always would be.

In the 18th century, geologists started to gather evidence that maybe the Earth hadn’t been around forever. Perhaps it was only millions or billions of years old. Maybe the Sun too, or even… the Universe. Maybe there was a time when there was nothing? Then, suddenly, pop… Universe.

It’s the science of thermodynamics that gave us our first insight. Over vast lengths of time, everything moves towards entropy, or maximum disorder. Just like a hot coffee cools down, all temperatures want to average out. And if the Universe was infinite in age, everything should be the same temperature. There should be no stars, planets, or us.

The brilliant Belgian priest and astronomer, George Lemaitre, proposed that the Universe must be either expanding or contracting. At some point, he theorized, the Universe would have been an infinitesimal point – he called it the primeval atom. And it was Edwin Hubble, in 1929 who observed that distant galaxies are moving away from us in all directions, confirming Lemaitre’s theories. Our Universe is clearly expanding.

Which means that if you run the clock backwards, and it was smaller in the distant past. And if you go back far enough, there’s a moment in time when the Universe began. Which means it has an age. The next challenge… figuring out the Universe’s birthdate.

Time line of the Universe (Credit: NASA/WMAP Science Team)

In 1958, the astronomer Allan Sandage used the expansion rate of the Universe, otherwise known as the Hubble Constant, to calculate how long it had probably been expanding. He came up with a figure of approximately 20 billion years. A more accurate estimation for the age of the Universe came with the discovery of the Cosmic Microwave Background Radiation; the afterglow of the Big Bang that we see in every direction we look.

Approximately 380,000 years after the Big Bang, our Universe had cooled to the point that protons and electrons could come together to form hydrogen atoms. At this point, it was a balmy 3000 Kelvin. Using this and by observing the background radiation, and how far the wavelengths of light have been stretched out by the expansion, astronomers were able to calculate how long it has been expanding for.

Initial estimates put the age of the Universe between 13 and 14 billion years old. But recent missions, like NASA’s WMAP mission and the European Planck Observatory have fine tuned that estimate with incredible accuracy. We now know the Universe is 13.8242 billion years, plus or minus a few million years.

We don’t know where it came from, or what caused it to come into being, but we know exactly how our Universe is. That’s a good start.

December 18, 2013March 14, 2017 by Fraser Cain

What Is The Big Rip?

Dr. Thad Szabo is a professor of physics and astronomy at Cerritos College. He’s also a regular contributor to many of our projects, like the Virtual Star Party and the Weekly Space Hangout. Thad has an encyclopedic knowledge of all things space, so we got him to explain a few fascinating concepts.

In this video, Thad explains the strange mystery of dark energy, and the even stranger idea of the Big Rip.

What is the ‘Big Rip?’

If we look at the expansion of the universe, at first it was thought that, as things are expanding while objects have mass, the mass is going to be attracted to other mass, and that should slow the expansion. Then, in the late 1990’s, you have the supernova surveys that are looking deeper into space than we’ve ever looked before, and measuring distances accurately to greater distances than we’ve ever seen before. Something really surprising came out, and that was what we’ll now use “dark energy” now to explain, and that is that the acceleration is not actually slowing down – it’s not even stopped. It’s actually getting faster, and if you look at the most distant objects, they’re actually moving away from us and the acceleration is increasing the acceleration of expansion. This is actually a huge result.

One of the ideas of trying to explain it is to use the “cosmological constant,” which is something that Einstein actually introduced to his field equations to try to keep the universe the same size. He didn’t like the idea of a universe changing, so he just kind of cooked up this term and threw it into the equations to say, alright, well if it isn’t supposed to expand or contract, if I make this little mathematical adjustment, it stays the same size.

Hubble comes along about ten years later, and is observing galaxies and measuring their red shifts and their distances, and says wait a minute – no the universe is expanding. And actually we should really credit that to Georges Lemaître, who was able to interpret Hubble’s data to come up with the idea of what we now call the Big Bang.

So, the expansion’s happening – wait, it’s getting faster. And now the attempt is to try to understand how dark energy works. Right now, most of the evidence points to this idea that the expansion will continue in the space between galaxies. That the forces of gravity, and especially magnetism and the strong nuclear force that holds protons and neutrons together in the center of an atom, would be strong enough that dark energy is never going to be able to pull those objects apart.

However, there’s a possibility that it doesn’t work like that. There’s actually a little bit of experimental evidence right now that, although it’s not well-established, that there’s a little bit of a bias with certain experiments that dark energy may get stronger over time. And, if it does so, the distances won’t matter – that any object will be pulled apart. So first, you will see all galaxies recede from each other, as space starts to grow bigger and bigger, faster and faster. Then the galaxies will start to be pulled apart. Then star systems, then planets from their stars, then stars themselves, and then other objects that would typically be held together by the much stronger forces, the electromagnetic force objects held by that will be pulled apart, and then eventually, nuclei in atoms.

So if dark energy behaves so that it gets stronger and stronger over time, it will eventually overcome everything, and you’ll have a universe with nothing left. That’s the ‘Big Rip’ – if dark energy gets stronger and stronger over time, it will eventually overcome any forces of attraction, and then everything is torn apart.

You can find more information from Dr. Thad Szabo at his YouTube channel.

December 16, 2013March 14, 2017 by Fraser Cain

Can Stars Collide?

Imagine a really bad day. Perhaps you’re imagining a day where the Sun crashes into another star, destroying most of the Solar System.

No? Well then, even in your imagination things aren’t so bad… It’s all just matter of perspective.

Fortunately for us, we live in out the boring suburbs of the Milky Way. Out here, distances between stars are so vast that collisions are incredibly rare. There are places in the Milky Way where stars are crowded more densely, like globular clusters, and we get to see the aftermath of these collisions. These clusters are ancient spherical structures that can contain hundreds of thousands of stars, all of which formed together, shortly after the Big Bang.

Within one of these clusters, stars average about a light year apart, and at their core, they can get as close to one another as the radius of our Solar System. With all these stars buzzing around for billions of years, you can imagine they’ve gotten up to some serious mischief.

Within globular clusters there are these mysterious blue straggler stars. They’re large hot stars, and if they had formed with the rest of the cluster, they would have detonated as supernovae billions of years ago. So scientists figure that they must have formed recently.

How? Astronomers think they’re the result of a stellar collision. Perhaps a binary pair of stars merged, or maybe two stars smashed into one another.

Professor Mark Morris of the University of California at Los Angeles in the Department of Physics and Astronomy helps to explain this idea.

“When you see two stars colliding with each other, it depends on how fast they’re moving. If they’re moving at speeds like we see at the center of our galaxy, then the collision is extremely violent. If it’s a head-on collision, the stars get completely splashed to the far corners of the galaxy. If they’re merging at slower velocities than we see at our neck of the woods in our galaxy, then stars are more happy to merge with us and coalesce into one single, more massive object.”

There’s another place in the Milky Way where you’ve got a dense collection of stars, racing around at breakneck speeds… near the supermassive black hole at the center of the galaxy.

This monster black hole contains the mass of 4 million times the Sun, and dominates the region around the center of the Milky Way.

This artist's concept illustrates a supermassive black hole with millions to billions times the mass of our sun. Supermassive black holes are enormously dense objects buried at the hearts of galaxies. Image credit: NASA/JPL-Caltech — Supermassive black holes are enormously dense objects buried at the hearts of galaxies. Image credit: NASA/JPL-Caltech

“The core of the Milky Way is one of those places where you find the extremes of nature. The density of stars there is higher than anywhere else in the galaxy,”Professor Morris continues. “Overall, in the center of our galaxy on scales of hundreds of light years, there is much more gas present than anywhere else in the galaxy. The magnetic field is stronger there than anywhere else in the galaxy, and it has it’s own geometry there. So it’s an unusual place, an energetic place, a violent place, because everything else is moving so much faster there than you see elsewhere.”

“We study the stars in the immediate vicinity of the black hole, and we find that there’s not as many stars as one might have expected, and one of the explanations for that is that stars collide with each other and either eliminate one another or merge, and two stars become one, and both of those processes are probably occurring.”

Stars whip around it, like comets dart around our Sun, and interactions are commonplace.

There’s another scenario that can crash stars together.

The Milky Way mostly has multiple star systems. Several stars can be orbiting a common center of gravity. Many are great distances, but some can have orbits tighter than the planets around our Sun.

When one star reaches the end of its life, expanding into a red giant, It can consume its binary partner. The consumed star then strips away 90% of the mass of the red giant, leaving behind a rapidly pulsating remnant.

What about when galaxies collide? That sounds like a recipe for mayhem.
Surprisingly, not so much.

“That’s actually a very interesting question, because if you imagine two galaxies colliding, you’d imagine that to be an exceptionally violent event,’ Professor Morris explains. “But in fact, the stars in those two galaxies are relatively unaffected. The number of stars that will collide when two galaxies collide is possibly counted on the fingers of one or two hands. Stars are so few and far between that they just aren’t going to meet each other with any significance in a field like that.”

Galaxy mergers, such as the Mice Galaxies will be part of Galaxy Zoo's newest project. Credit: Hubble Space Telescope — The Mice galaxies merging. Credit: Hubble Space Telescope

“What you see when you see two galaxies collide, however, on the large scale, is that the tidal forces of the two galaxies will rip each of the galaxies apart in terms of what it will look like. Streams of stars will be strewn out in various directions depending on the precise history of the interaction between the two galaxies. And so, eventually over time, the galaxies will merge, the whole configuration of stars will settle down into something that looks unlike either of the two initially colliding galaxies. Perhaps something more spheroidal or spherical, and it might look more like an elliptical galaxy than the spiral galaxy that these two galaxies now are.”

Currently, we’re on a collision course with the Andromeda Galaxy, and it’s expected we’ll smash into it in about 4 billion years. The gas and dust will collide and pile up, igniting an era of furious star formation. But the stars themselves? They’ll barely notice. The stars in the two galaxies will just streak past each other, like a swarm of angry bees.

Phew.

So, good news! When you’re imagining a worse day, you won’t have to worry about our Sun colliding with another star. We’re going to be safe and sound for billions of years. But if you live in a globular cluster or near the center of the galaxy, you might want to check out some property here in the burbs.

Thanks to Professor Mark Morris at UCLA – visit their Physics and Astronomy program homepage here.

December 12, 2013March 14, 2017 by Fraser Cain

Is Everything in the Universe Expanding?

The Universe is expanding. Distant galaxies are moving away from us in all directions. It’s natural to wonder, is everything expanding? Is the Milky Way expanding? What about the Solar System, or even objects here on Earth. Are atoms expanding?

Nope. The only thing expanding is space itself. Imagine the Universe as loaf of raisin bread rising in the oven. As the bread bakes, it’s stretching in all directions – that’s space. But the raisins aren’t growing, they’re just getting carried away from each other as there’s more bread expanding between them.

Space is expanding from the Big Bang and the acceleration of dark energy. But the objects embedded in space, like planets, stars, and galaxies stay exactly the same size. As space expands, it carries galaxies away from each other. From our perspective, we see galaxies moving away in every direction. The further galaxies are, the faster they’re moving.

There are a few exceptions. The Andromeda Galaxy is actually moving towards the Milky Way, and will collide with us in about 4 billion years.In this case, the pull of gravity between the Milky Way and Andromeda is so strong that it overcomes the expansion of the Universe on a local level.

Within the Milky Way, gravity holds the stars together, and same with the Solar System. The nuclear force holding atoms together is stronger than this expansion at a local scale. Is this the way it will always be? Maybe. Maybe not.

A few decades ago, astronomers thought that the Universe was expanding because of momentum left over from the Big Bang. But with the discovery of dark energy in 1998, astronomers realized there was a new possibility for the future of the Universe. Perhaps this accelerating dark energy might be increasing over time.

In billions years from now, the expansive force might overcome the gravity that holds galaxies together. Eventually it would become so strong that star systems, planets and eventually matter itself could get torn apart.This is a future for the Universe known as the Big Rip. And if it’s true, then the space between stars, planets and even atoms will expand in the far future.

This image shows the Hubble Ultra Deep Field 2012, an improved version of the Hubble Ultra Deep Field image featuring additional observation time. The new data have revealed for the first time a population of distant galaxies at redshifts between 9 and 12, including the most distant object observed to date. These galaxies will require confirmation using spectroscopy by the forthcoming NASA/ESA/CSA James Webb Space Telescope before they are considered to be fully confirmed. — The space between the galaxies is expanding. Credit: NASA/HST

Is this going to happen? Astronomers don’t know. Their best observations so far can’t rule it out, or confirm it. And so, future observations and space missions will try to calculate the rate of dark energy’s expansion.

So no, matter on a local level isn’t expanding. The spaces between planets and stars isn’t growing. Only the distances between galaxies which aren’t gravitationally bound to each other is increasing. Because space itself is expanding.

December 2, 2013March 14, 2017 by Fraser Cain

How Does a Star Form?

We owe our entire existence to the Sun. Well, it and the other stars that came before. As they died, they donated the heavier elements we need for life. But how did they form?

Stars begin as vast clouds of cold molecular hydrogen and helium left over from the Big Bang. These vast clouds can be hundreds of light years across and contain the raw material for thousands or even millions of times the mass of our Sun. In addition to the hydrogen, these clouds are seeded with heavier elements from the stars that lived and died long ago. They’re held in balance between their inward force of gravity and the outward pressure of the molecules. Eventually some kick overcomes this balance and causes the cloud to begin collapsing.

That kick could come from a nearby supernova explosion, collision with another gas cloud, or the pressure wave of a galaxy’s spiral arms passing through the region. As this cloud collapses, it breaks into smaller and smaller clumps, until there are knots with roughly the mass of a star. As these regions heat up, they prevent further material from falling inward.

At the center of these clumps, the material begins to increase in heat and density. When the outward pressure balances against the force of gravity pulling it in, a protostar is formed. What happens next depends on the amount of material.

Some objects don’t accumulate enough mass for stellar ignition and become brown dwarfs – substellar objects not unlike a really big Jupiter, which slowly cool down over billions of years.

If a star has enough material, it can generate enough pressure and temperature at its core to begin deuterium fusion – a heavier isotope of hydrogen. This slows the collapse and prepares the star to enter the true main sequence phase. This is the stage that our own Sun is in, and begins when hydrogen fusion begins.

If a protostar contains the mass of our Sun, or less, it undergoes a proton-proton chain reaction to convert hydrogen to helium. But if the star has about 1.3 times the mass of the Sun, it undergoes a carbon-nitrogen-oxygen cycle to convert hydrogen to helium. How long this newly formed star will last depends on its mass and how quickly it consumes hydrogen. Small red dwarf stars can last hundreds of billions of years, while large supergiants can consume their hydrogen within a few million years and detonate as supernovae. But how do stars explode and seed their elements around the Universe? That’s another episode.

We have written many articles about star formation on Universe Today. Here’s an article about star formation in the Large Magellanic Cloud, and here’s another about star formation in NGC 3576.

Want more information on stars? Here’s Hubblesite’s News Releases about Stars, and more information from NASA’s imagine the Universe.

We have recorded several episodes of Astronomy Cast about stars. Here are two that you might find helpful: Episode 12: Where Do Baby Stars Come From, and Episode 13: Where Do Stars Go When they Die?

Source: NASA

November 28, 2013March 16, 2017 by Fraser Cain

What is the Universe Expanding Into?

Come on, admit it, you’ve had this question. “Since astronomers know that the Universe is expanding, what’s it expanding into? What’s outside of the Universe?” Ask any astronomer and you’ll get an unsatisfying answer. We give you the same unsatisfying answer, but really explain it, so your unsatisfaction doesn’t haunt you any more.

The short answer is that this is a nonsense question, the Universe isn’t expanding into anything, it’s just expanding.

The definition of the Universe is that it contains everything. If something was outside the Universe, it would also be part of the Universe too. Outside of that? Still Universe. Out side of THAT? Also more Universe. It’s Universe all the way down. But I know you’re going to find that answer unsatisfying, so now I’m going to break your brain.

Either the Universe is infinite, going on forever, or its finite, with a limited volume. In either case, the Universe has no edge. When we imagine the Universe expanding after the Big Bang, we imagine an explosion, with a spray of matter coming from a single point. But this analogy isn’t accurate.

A better analogy is the surface of an expanding balloon. Not the 3 dimensional balloon, just its 2 dimensional surface. If you were an ant crawling around the surface of a huge balloon, and the balloon was your whole universe, you would see the balloon as essentially flat under your feet.

Imagine the balloon is inflating. In every direction you look, other ants are moving away from you. The further they are, the faster away they’re moving. Even though it feels like a flat surface, walk in any direction long enough and you’d return to your starting point.

You might imagine a growing circle and wonder what it’s expanding into. But that’s a nonsense question. There’s no direction you could crawl that would get you outside the surface. Your 2-dimensional ant brain can’t comprehend an expanding 3-dimensional object. There may be a center to the balloon, but there’s no center to the surface. Just a shape that extends in all directions and wraps in upon itself. And yet, your journey to make one lap around the balloon takes longer and longer as the balloon gets more inflated.

To better understand how this relates to our Universe, we need to scale things up by one dimension, from a 2-d surface embedded in a 3-d world, to a 3-d volume embedded within a 4-d universe. Astronomers think that if you travel in any direction far enough, you’ll return to your starting position. If you could stare far enough into space, you would be looking at the back of your own head.

The Universe 1.6 billion years after the Big Bang. Image credit: Paul Bode and Yue Shen

And so, as the Universe expands, it would take you longer and longer to lap the Universe and return to your starting position. But there’s no direction you could travel in that would take you outside or “off” of the Universe. Even if you could move faster than the speed of light, you’d just return to your starting position more quickly. We see other galaxies moving away from us in all directions just as our ant would see other ants moving away on the surface of the balloon.

A great analogy comes from my Astronomy Cast co-host, Dr. Pamela Gay. Instead of an explosion, imagine the expanding Universe is like a loaf of raisin bread rising in the oven. From the perspective of any raisin, all the other raisins are moving away in all directions. But unlike a loaf of raisin bread, you could travel in any one direction within the bread and eventually return to your starting raisin.

Remember that our entire comprehension is based on 3-dimensions. If we were 4-dimensional creatures, this would make much more sense. For a much deeper explanation, I highly recommend you watch my good friend, Zogg the Alien explain how the Universe has no edge. After watching his videos, you should totally understand the possible topologies of our Universe.

I hope this helps you understand why there’s no answer to “what is the Universe expanding into?” With no edge, it’s not expanding into anything, it’s just expanding.

You can also listen to our podcast episode explaining this here –
What is the Universe Expanding Into – Show notes and transcript

Or subscribe to: astronomycast.com/podcast.xml

November 18, 2013March 16, 2017 by Fraser Cain

What Is The Evidence For The Big Bang?

Almost all astronomers agree on the theory of the Big Bang, that the entire Universe is spreading apart, with distant galaxies speeding away from us in all directions. Run the clock backwards to 13.8 billion years ago, and everything in the Cosmos started out as a single point in space. In an instant, everything expanded outward from that location, forming the energy, atoms and eventually the stars and galaxies we see today. But to call this concept merely a theory is to misjudge the overwhelming amount of evidence.

There are separate lines of evidence, each of which independently points towards this as the origin story for our Universe. The first came with the amazing discovery that almost all galaxies are moving away from us.

In 1912, Vesto Slipher calculated the speed and direction of “spiral nebulae” by measuring the change in the wavelengths of light coming from them. He realized that most of them were moving away from us. We now know these objects are galaxies, but a century ago astronomers thought these vast collections of stars might actually be within the Milky Way.

In 1924, Edwin Hubble figured out that these galaxies are actually outside the Milky Way. He observed a special type of variable star that has a direct relationship between its energy output and the time it takes to pulse in brightness. By finding these variable stars in other galaxies, he was able to calculate how far away they were. Hubble discovered that all these galaxies are outside our own Milky Way, millions of light-years away.

So, if these galaxies are far, far away, and moving quickly away from us, this suggests that the entire Universe must have been located in a single point billions of years ago. The second line of evidence came from the abundance of elements we see around us.

In the earliest moments after the Big Bang, there was nothing more than hydrogen compressed into a tiny volume, with crazy high heat and pressure. The entire Universe was acting like the core of a star, fusing hydrogen into helium and other elements.

This is known as Big Bang Nucleosynthesis. As astronomers look out into the Universe and measure the ratios of hydrogen, helium and other trace elements, they exactly match what you would expect to find if the entire Universe was once a really big star.

Line of evidence number 3: cosmic microwave background radiation. In the 1960s, Arno Penzias and Robert Wilson were experimenting with a 6-meter radio telescope, and discovered a background radio emission that was coming from every direction in the sky – day or night. From what they could tell, the entire sky measured a few degrees above absolute zero.

WMAP data of the Cosmic Microwave Background. Credit: NASA

Theories predicted that after a Big Bang, there would have been a tremendous release of radiation. And now, billions of years later, this radiation would be moving so fast away from us that the wavelength of this radiation would have been shifted from visible light to the microwave background radiation we see today.

The final line of evidence is the formation of galaxies and the large scale structure of the cosmos. About 10,000 years after the Big Bang, the Universe cooled to the point that the gravitational attraction of matter was the dominant form of energy density in the Universe. This mass was able to collect together into the first stars, galaxies and eventually the large scale structures we see across the Universe today.

These are known as the 4 pillars of the Big Bang Theory. Four independent lines of evidence that build up one of the most influential and well-supported theories in all of cosmology. But there are more lines of evidence. There are fluctuations in the cosmic microwave background radiation, we don’t see any stars older than 13.8 billion years, the discoveries of dark matter and dark energy, along with how the light curves from distant supernovae.

So, even though it’s a theory, we should regard it the same way that we regard gravity, evolution and general relativity. We have a pretty good idea of what’s going on, and we’ve come up with a good way to understand and explain it. As time progresses we’ll come up with more inventive experiments to throw at. We’ll refine our understanding and the theory that goes along with it.

Most importantly, we can have confidence when talking about what we know about the early stages of our magnificent Universe and why we understand it to be true.

October 1, 2013December 23, 2015 by Elizabeth Howell

This Very Old Cosmic Light Has A Bend To It

Artist's impression of how huge cosmic structures deflect photons in the cosmic microwave background (CMB). Credit: ESA and the Planck Collaboration

Leftover radiation from the Big Bang — that expansion that kick-started the universe — can be bent by huge cosmic structures, just like other light that we see in the universe. While the finding seems esoteric at first glance, scientists say the discovery could pave the way for finding a similar kind of signal that indicate the presence of gravitational waves in the moments after the universe was born.

That light is called the cosmic microwave background and is the radiation that was visible when the universe became transparent to radiation, 380,000 years after the Big Bang. A tiny bit of the CMB is polarized. There are two types of polarized light in the CMB: E-modes (first detected in 2002) and B-modes (which were just detected using a telescope in Antarctica and ESA’s Herschel space observatory.

“[B-modes] can arise in two ways,” the European Space Agency wrote in a press release.

“The first involves adding a twist to the light as it crosses the Universe and is deflected by galaxies and dark matter – a phenomenon known as gravitational lensing. The second has its roots buried deep in the mechanics of a very rapid phase of enormous expansion of the Universe, which cosmologists believe happened just a tiny fraction of a second after the Big Bang – ‘inflation’.”

More results are on the way from ESA’s Planck telescope in 2014, at which point scientists hope to see this B-mode of the second type. For now, check out the full study in Physical Review Letters. There is also a preprint version available on Arxiv.

Sources: ESA and ESA Herschel

September 3, 2013April 26, 2016 by Elizabeth Howell

Big Bang’s Sound-Like Waves Show Up In Lab Simulation

Tracing back to the Big Bang. Image credit: Ivo LabbÃ©

An ultracold vacuum chamber ran a simulation of the early universe and came up with some interesting findings about how the environment looked shortly after the Big Bang occurred.

Specifically, the atoms clustered in patterns similar to the cosmic microwave background — believed to be the echo of the intense burst that formed the beginning of the universe. Scientists have mapped the CMB at progressively higher resolution using several telescopes, but this experiment is the first of its kind to show how structure evolved at the beginning of time as we understand it.

The Big Bang theory (not to be confused with the popular television show) is intended to describe the universe’s evolution. While many pundits say it shows how the universe came “from nothing”, the concordance cosmological model that describes the theory says nothing about where the universe came from. Instead, it focuses on applying two big physics models (general relativity and the standard model of particle physics). Read more about the Big Bang here.

CMB is, more simply stated, electromagnetic radiation that fills the Universe. Scientists believe it shows an echo of a time when the Universe was much smaller, hotter and denser, and filled to the brim with hydrogen plasma. The plasma and radiation surrounding it gradually cooled as the Universe grew bigger. (More information on the CMB is here.) At one time, the glow from the plasma was so dense that the Universe was opaque, but transparency increased as stable atoms formed. But the leftovers are still visible in the microwave range.

The new research used ultracold cesium atoms in a vacuum chamber at the University of Chicago. When the team cooled these atoms to a billionth of a degree above absolute zero (which is -459.67 degrees Fahrenheit, or -273.15 degrees Celsius), the structures they saw appeared very similar to the CMB.

By quenching the 10,000 atoms in the experiment to control how strongly the atoms interact with each other, they were able to generate a phenomenon that is, very roughly speaking, similar to how sound waves move in air.

“At this ultracold temperature, atoms get excited collectively,” stated Cheng Chin, a physics researcher at the University of Chicago who participated in the research. This phenomenon was first described by Russian physicist Andrei Sakharov, and is known as Sakharov acoustic oscillations.

So why is the experiment important? It allows us to more closely track what happened after the Big Bang.

Atom density is greater at left (the beginning of the experiment) than 80 milliseconds after the simulated Big Bang. Credit: Chen-Lung Hung

The CMB is simply a frozen moment of time and is not evolving, requiring researchers to delve into the lab to figure out what is happening.

“In our simulation we can actually monitor the entire evolution of the Sakharov oscillations,” said Chen-Lung Hung, who led the research, earned his Ph.D. in 2011 at the University of Chicago, and is now at the California Institute of Technology.

Both Hung and Chin plan to do more work with the ultracold atoms. Future research directions could include things such as how black holes work, or how galaxies were formed.

You can read the published research online on Science‘s website.

Source: University of Chicago

August 30, 2013December 30, 2015 by Jason Major

Why “The Big Bang” Is a Terrible Name

Have a discussion about the origins of the Universe and, ere long, someone will inevitably use the term “the Big Bang” to describe the initial moment of expansion of everything that was to everything that is. But in reality “Big Bang” isn’t a very good term since “big” implies size (and when it occurred space didn’t technically exist yet) and there was no “bang.” In fact the name wasn’t ever even meant to be an official moniker, but once it was used (somewhat derisively) by British astronomer Sir Fred Hoyle in a radio broadcast in 1949, it stuck.

Unfortunately it’s just so darn catchy.

This excellent video from minutephysics goes a bit more into depth as to why the name is inaccurate — even though we’ll likely continue using it for quite some time. (Thanks to Sir Hoyle.)

And you have to admit, a television show called “The Everywhere Stretch Theory” would never have caught on. Bazinga!