A teeny, tiny, minuscule portion of Martin Vargic’s Timeline of the Universe.
Don’t know much about history? How about the future? A new infographic by graphic designer Martin Vargic portrays both past and forthcoming events in our Universe, from the Big Bang to the death of our Sun. The graphic is color-coded and shows “significant events in cosmic and natural history.” It also illustrates how briefly humanity has been part of the scene.
Fun future events are when Earth’s day will become 25 hours long (Earth’s rotation is slowing down), and the amazingly distant time when the Solar System finally completes one orbit around the galactic core.
A simulation of galaxies during the era of deionization in the early Universe. Credit: M. Alvarez, R. Kaehler, and T. AbelCredit: M. Alvarez, R. Kaehler, and T. Abel
In the beginning, there was chaos.
Hot, dense, and packed with energetic particles, the early Universe was a turbulent, bustling place. It wasn’t until about 300,000 years after the Big Bang that the nascent cosmic soup had cooled enough for atoms to form and light to travel freely. This landmark event, known as recombination, gave rise to the famous cosmic microwave background (CMB), a signature glow that pervades the entire sky.
Now, a new analysis of this glow suggests the presence of a pronounced bruise in the background — evidence that, sometime around recombination, a parallel universe may have bumped into our own.
Although they are often the stuff of science fiction, parallel universes play a large part in our understanding of the cosmos. According to the theory of eternal inflation, bubble universes apart from our own are theorized to be constantly forming, driven by the energy inherent to space itself.
Like soap bubbles, bubble universes that grow too close to one another can and do stick together, if only for a moment. Such temporary mergers could make it possible for one universe to deposit some of its material into the other, leaving a kind of fingerprint at the point of collision.
Ranga-Ram Chary, a cosmologist at the California Institute of Technology, believes that the CMB is the perfect place to look for such a fingerprint.
The cosmic microwave background (CMB), a pervasive glow made of light from the Universe’s infancy, as seen by the Planck satellite in 2013. Tiny deviations in average temperature are represented by color. Credit: ESA and the Planck Collaboration.
After careful analysis of the spectrum of the CMB, Chary found a signal that was about 4500x brighter than it should have been, based on the number of protons and electrons scientists believe existed in the very early Universe. Indeed, this particular signal — an emission line that arose from the formation of atoms during the era of recombination — is more consistent with a Universe whose ratio of matter particles to photons is about 65x greater than our own.
There is a 30% chance that this mysterious signal is just noise, and not really a signal at all; however, it is also possible that it is real, and exists because a parallel universe dumped some of its matter particles into our own Universe.
After all, if additional protons and electrons had been added to our Universe during recombination, more atoms would have formed. More photons would have been emitted during their formation. And the signature line that arose from all of these emissions would be greatly enhanced.
Chary himself is wisely skeptical.
“Unusual claims like evidence for alternate Universes require a very high burden of proof,” he writes.
Indeed, the signature that Chary has isolated may instead be a consequence of incoming light from distant galaxies, or even from clouds of dust surrounding our own galaxy.
View showing actual flight structure of mirror backplane unit for NASA's James Webb Space Telescope (JWST) that holds 18 segment primary mirror array and secondary mirror mount at front, in stowed-for-launch configuration. JWST is being assembled here by technicians inside the world’s largest cleanroom at NASA Goddard Space Flight Center, Greenbelt, Md. Credit: Ken Kremer/kenkremer.com
View showing actual flight structure of mirror backplane unit for NASA’s James Webb Space Telescope (JWST) that holds 18 segment primary mirror array and secondary mirror mount at front, in stowed-for-launch configuration. JWST is being assembled here by technicians inside the world’s largest cleanroom at NASA Goddard Space Flight Center, Greenbelt, Md. Credit: Ken Kremer/kenkremer.com
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NASA GODDARD SPACE FLIGHT CENTER, MD – The construction pace for NASA’s James Webb Space Telescope (JWST) took a major leap forward with delivery of the actual flight structure that serves as the observatory’s critical mirror holding backbone – to NASA’s Goddard Space Flight Center in Greenbelt, Maryland and observed by Universe Today.
“We are in good shape with the James Webb Space Telescope,” said Dr. John Mather, NASA’s Nobel Prize Winning scientist, in an exclusive interview with Universe Today at NASA Goddard during a visit to the flight structure – shown in my photos herein. Note: Read an Italian language version of this story – here at Alive Universe
And the mammoth $8.6 Billion Webb telescope has mammoth scientific objectives as the scientific successor to NASA’s Hubble Space Telescope (HST) – now celebrating its 25th anniversary in Earth orbit.
“JWST has the capability to look back towards the very first objects that formed after the Big Bang,” Mather told Universe Today.
How is that possible?
“James Webb has a much bigger mirror than Hubble. So its resolution is much better,” said astronaut and NASA science chief John Grunsfeld, during an exclusive interview at NASA Goddard. Grunsfeld flew on a trio of Hubble servicing missions aboard the Space Shuttle, including the final one during STS-125 in 2009.
“JWST can look back further in time, and a greater distance than Hubble, so we can see those first stars and galaxies formed in the Universe.”
These discoveries are only possible with Webb, which will become the most powerful telescope ever sent to space when it launches in 2018.
Up close view of actual side wing backplane of NASA’s James Webb Space Telescope (JWST) that will hold 3 of the observatory’s 18 primary mirrors, as technicians work inside cleanroom at NASA Goddard Space Flight Center, Greenbelt, Md. Credit: Ken Kremer/kenkremer.com
The massive JWST flight structure unit includes the “backplane assembly” that clasps in place all of the telescopes primary and secondary mirrors, as well as its ISIM science module loaded with the observatory’s quartet of state-of-the-art research instruments.
“The backplane looks really great,” Grunsfeld told me.
Numerous NASA centers and aerospace companies are involved in building the observatory and its backplane structure holding the mirrors that will search back some 13.4 billion years.
“The backplane structure just arrived in late August from Northrop Grumman Aerospace Systems in Redondo Beach, California,” said Sandra Irish, JWST lead structural engineer during an interview with Universe Today at the NASA Goddard cleanroom facility.
“This is the actual flight hardware.”
Side view of flight unit mirror backplane assembly structure for NASA’s James Webb Space Telescope (JWST) that holds primary mirror array and secondary mirror mount in stowed-for-launch configuration. JWST is being assembled technicians inside the cleanroom at NASA Goddard Space Flight Center, Greenbelt, Md. Credit: Ken Kremer/kenkremer.com
The purpose of JWST’s backplane assembly is to hold the telescopes 18 segment, 21-foot (6.5-meter) diameter primary mirror nearly motionless while floating in the utterly frigid space environment, thereby enabling the observatory to peer out into deep space for precise science gathering measurements never before possible.
The massive telescope structure “includes the primary mirror backplane assembly; the main backplane support fixture; and the deployable tower structure that lifts the telescope off of the spacecraft. The three arms at the top come together into a ring where the secondary mirror will reside,” say officials.
The backplane traveled a long and winding road before arriving at Goddard.
“The backplane structure was designed and built at Orbital ATK with NASA oversight,” Irish explained. The assembly work was done at the firms facilities in Magna, Utah.
“Then it was sent to Northrop Grumman in Redondo Beach, California for static testing. Then it came here to Goddard. Orbital ATK also built the composite tubes for the ISIM science module structure.”
The observatory’s complete flight structure measures about 26 feet (nearly 8 meters) from its base to the tip of the tripod arms and mirror mount holding the round secondary mirror.
Artist’s concept of the James Webb Space Telescope (JWST) with Sunshield at bottom. Credit: NASA/ESA
The flight structure and backplane assembly arrived at Goddard in its stowed-for-launch configuration after being flown cross country from California.
“It is here for the installation of all the mirrors to build up the entire telescope assembly here at Goddard. It will be fully tested here before it is delivered to the Johnson Space Center in Houston and then back to California,” Irish elaborated.
The overall assembly is currently attached to a pair of large yellow and white fixtures that firmly secure the flight unit, to stand it upright and rotate as needed, as it undergoes acceptance testing by engineers and technicians before commencement of the next big step – the crucial mirror installation that starts soon inside the world’s largest cleanroom at NASA Goddard.
Overhead cranes are also used to maneuver the observatory structure as engineers inspect and test the unit.
But several weeks of preparatory work are in progress before the painstakingly precise mirror installation can begin under the most pristine cleanroom operating conditions.
“Right now the technicians are installing harnesses that we need to mount all over the structure,” Irish told me.
“These harnesses will go to our electronic systems and the mirrors in order to monitor their actuation on orbit. So that’s done first.”
What is the construction sequence at Goddard for the installation of the mirrors and science instruments and what comes next?
“This fall we will be installing every mirror, starting around late October/early November. Then next April 2016 we will install the ISIM science module inside the backplane structure.”
“The ISIM mounts all four of the telescope science instrument. So the mirrors go on first, then the ISIM gets installed and then it will really be the telescope structure.” ISIM carries some 7,500 pounds (2400 kg) of telescope optics and instruments.
“Then starting about next July/August 2016 we start the environmental testing.”
The actual flight mirror backplane is comprised of three segments – the main central segment and a pair of outer wing-like parts holding three mirrors each. They will be unfolded from the stowed-for-launch configuration to the “deployed” configuration to carry out the mirror installation. Then be folded back over into launch configuration for eventual placement inside the payload fairing of the Ariane V ECA booster rocket.
The telescope will launch from the Guiana Space Center in Kourou, French Guiana in 2018.
Gold coated flight spare of a JWST primary mirror segment made of beryllium and used for test operations inside the NASA Goddard clean room. Credit: Ken Kremer- kenkremer.com
The telescopes primary and secondary flight mirrors have already arrived at Goddard.
The mirrors must remained precisely aligned and nearly motionless in order for JWST to successfully carry out science investigations. While operating at extraordinarily cold temperatures between -406 and -343 degrees Fahrenheit the backplane must not move more than 38 nanometers, approximately 1/1,000 the diameter of a human hair.
To account for the tiniest of errors and enhance science, each of the primary mirrors is equipped with actuators for minute adjustments.
“A beautiful advantage of Webb that’s different from Hubble is the fact that we do have actuation [capability] of every single one of our mirrors. So if we are off by just a little bit on either our calculations or from misalignment from launch or the zero gravity release, we can do some fine adjustments on orbit.”
“We can adjust every mirror within 50 nanometers.”
“That’s important because we can’t send astronauts to fix our telescope. We just can’t.”
“The telescope is a million miles away.”
NASA’s team at Goddard has already practiced mirror installation because there are no second chances.
“We only have one shot to get this right!” Irish emphasized.
Watch for more on the mirror installation in my upcoming story.
JWST is the successor to the 25 year old Hubble Space Telescope and will become the most powerful telescope ever sent to space.
Webb is designed to look at the first light of the Universe and will be able to peer back in time to when the first stars and first galaxies were forming.
The Webb Telescope is a joint international collaborative project between NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA).
NASA has overall responsibility and Northrop Grumman is the prime contractor for JWST.
“The telescope is on schedule for its launch in 2018 in October,” Mather told me.
And the payoff from JWST will be monumental!
“On everything from nearby planets to the most distant universe, James Webb will transform our view of the Universe,” Grunsfeld beams.
Watch for more on JWST construction and mirror installation in part 2 soon.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
A comparison of the primary mirror used by Hubble and the primary mirror array used by the James Webb Space Telescope. Photo Credit: NASANASA Science chief and astronaut John Grunsfeld discusses James Webb Space Telescope project at NASA Goddard Space Flight Center in Maryland. Credit: Ken Kremer/kenkremer.com
Two possiblities exist: either the Universe is finite and has a size, or it’s infinite and goes on forever. Both possibilities have mind-bending implications.
In another episode of Guide to Space, we talked: “how big is our Universe”. Then I said it all depends on whether the Universe is finite or infinite. I mumbled, did some hand waving, glossed over the mind-bending implications of both possibilities and moved on to whatever snarky sci-cult reference was next because I’m a bad host. I acted like nothing happened and immediately got off the elevator.
So, in the spirit of he who smelled it, dealt it. I’m back to shed my cone of shame and talk big universe. And if the Universe is finite, well, it’s finite. You could measure its size with a really long ruler. You could also follow up statements like that with all kinds of crass shenanigans. Sure, it might wrap back on itself in a mindbending shape, like a of monster donut or nerdecahedron, but if our Universe is infinite, all bets are off. It just goes on forever and ever and ever in all directions. And my brain has already begun to melt in anticipation of discussing the implications of an infinite Universe.
Haven’t astronomers tried to figure this out? Of course they have, you fragile mortal meat man/woman! They’ve obsessed over it, and ordered up some of the most powerful sensitive space satellites ever built to answer this question.Astronomers have looked deep at the Cosmic Microwave Background Radiation, the afterglow of the Big Bang. So, how would you test this idea just by watching the sky?
Here’s how smart they are. They’ve searched for evidence that features on one side of the sky are connected to features on the other side of the sky, sort of like how the sides of a Risk map connect to each other, or there’s wraparound on the PacMan board. And so far, there’s no evidence they’re connected.
In our hu-man words, this means 13.8 billion light-years in all directions, the Universe doesn’t repeat. Light has been travelling towards us for 13.8 billion years this way, and 13.8 billion years that way, and 13.8 billion years that way; and that’s just when the light left those regions. The expansion of the Universe has carried them from 47.5 billion light years away. Based on this, our Universe is 93 billion light-years across. That’s an “at least” figure. It could be 100 billion light-years, or it could be a trillion light-years. We don’t know. Possibly, we can’t know. And it just might be infinite.
If the Universe is truly infinite, well then we get a very interesting outcome; something that I guarantee will break your brain for the entire day. After moments like this, I prefer to douse it in some XKCD, Oatmeal and maybe some candy crush.
Artist’s conception of Planck, a space observatory operated by the European Space Agency, and the cosmic microwave background. Credit: ESA and the Planck Collaboration – D. Ducros
Consider this. In a cubic meter (or yard) of space. Alright, in a box of space about yay big (show with hands), there’s a finite number of particles that can possibly exist in that region, and those particles can have a finite number of configurations considering their spin, charge, position, velocity and so on.
Tony Padilla from Numberphile has estimated that number to be 10 to the power of 10 to the power of 70. That’s a number so big that you can’t actually write it out with all the pencils in the Universe. Assuming of course, that other lifeforms haven’t discovered infinite pencil technology, or there’s a pocket dimension containing only pencils. Actually, it’s probably still not enough pencils.
There are only 10 ^ 80 particles in the observable Universe, so that’s much less than the possible configurations of matter in a cubic meter. If the Universe is truly infinite, if you travel outwards from Earth, eventually you will reach a place where there’s a duplicate cubic meter of space. The further you go, the more duplicates you’ll find.
Ooh, big deal, you think. One hydrogen pile looks the same as the next to me. Except, you hydromattecist, you’ll pass through places where the configuration of particles will begin to appear familiar, and if you proceed long enough you’ll find larger and larger identical regions of space, and eventually you’ll find an identical you. And finding a copy of yourself is just the start of the bananas crazy things you can do in an infinite Universe.
The Hubble Ultra Deep Field seen in ultraviolet, visible, and infrared light. Image Credit: NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)
In fact, hopefully you’ll absorb the powers of an immortal version of you, because if you keep going you’ll find an infinite number of yous. You’ll eventually find entire duplicate observable universes with more yous also collecting other yous. And at least one of them is going to have a beard.
So, what’s out there? Possibly an infinite number of duplicate observable universes. We don’t even need multiverses to find them. These are duplicate universes inside of our own infinite universe. That’s what you can get when you can travel in one direction and never, ever stop.
Whether the Universe is finite or infinite is an important question, and either outcome is mindblenderingly fun. So far, astronomers have no idea what the answer is, but they’re working towards it and maybe someday they’ll be able to tell us.
So what do you think? Do we live in a finite or infinite universe? Tell us in the comments below.
Imagine the Big Bang, and you’re imagining an explosion. There must be come place we could travel in the Universe and see the wreckage left over from the Big Bang. So, where is it?
Close your eyes and imagine the Big Bang. That first moment, where all the energy, matter and light came into existence. It’s an explosion right? Fire, debris, sinks, marmots and anvils flying past the camera in an ever expanding cloud of hot gas.
And like any explosion, there must be an aftermath, right? Some place we could travel in the Universe and see the exact spot that everything began; the exact location where the Big Bang happened and ideally a huge crater in spacetime where the Universe began.
I expect you’re imagining our little scene in your mind. Complete with space-time indentations and orbital detritus. I hope you’re also getting the unsettling feeling of dread that I’m about to smash up beloved sci-fi tropes for my own amusement. And here it is…
There’s no exact spot that the Big Bang happened. In fact, the Big Bang happened everywhere in the Universe. The problem generally comes from the term “Big Bang”. It brings to mind explosions, detonations, balloons being popped, and everything being blown out to chickenbasket hades. It’s too bad for us regular folk, this isn’t a good descriptive term for what the Big Bang was.
So I’m going to propose a new term, and just use it from here on out, and pretend like it was always this way. So, from here on out, I’m going to call it the Big Stretch, and by that I mean I’ve always called it the Big Stretch, and for those of you familiar with this type of retconning, the chocolate ration is being increased from 40 grams to 25 grams.
Imagine a balloon covered in dots, then inflate the balloon. Also, for the purposes of this illustration, you’re a 2-dimensional creature living at one of those dots and watching all the other dots. From your perspective, everything will smell like that weird damp spit and rubber balloon scent.
You’ll also see all other other dots moving away from you. You might even think you’re at the center of the expansion of the balloon. And then if you jumped to any other dot, you’d see the same thing. Just smelly dots, all racing away from you.
Expansion of the Universe. Image credit: Eugenio Bianchi, Carlo Rovelli & Rocky Kolb.
Now a lesser being would get all caught up thinking about the fact that the balloon is a three-dimensional object, and the center of the expansion is actually at the middle of the balloon. But you’re a 2D creature. You can’t comprehend anything but the surface of the balloon. That and the funky smell.
Now take that concept and scale it up one more dimension. As a three-dimensional creature trapped within a three-dimensional Universe witnessing it stretching out three dimensions. Every galaxy is moving away from you. But if you travel to any other galaxy, it looks like all the other galaxies are moving away from them.
Could a four-dimensional being find the center of the expansion, the place where the Big Bang happened? Probably. 4D beings are cool like that. But then, a 5D being would probably laugh at their simplistic 4D view of the Universe, with their quaint Klein bottles and rustic hypercubes. Suck it 4D jerks, they’d say, and then they’d trap them in their 5D lockers for the entirety of recess until the janitor heard the banging and let them out.
And don’t get me started on those 11D jerks. Those guys are awful, and they really think they’re better than everyone else. They’re like Greg Marmand from Omega House but with 8 more dimensions of nose to look down at you across.
So, where did the Big Bang happen? It happened everywhere. All places formed in the Big Bang – I mean – Big Stretch, and they’ve been moving away from each other for 13.8 billion years. There’s no one place you can point to and say: the Big Bang happened there.But you can be totally obnoxious and point to anywhere, and say the Big Bang happened there. Since the Big Bang happened everywhere, it happened in your hometown. Tell us where you’re from in the comments below.
Hubble Frontier Fields observing programme, which is using the magnifying power of enormous galaxy clusters to peer deep into the distant Universe. Credit: NASA.
Gravity’s a funny thing. Not only does it tug away at you, me, planets, moons and stars, but it can even bend light itself. And once you’re bending light, well, you’ve got yourself a telescope.
Everyone here is familiar with the practical applications of gravity. If not just from exposure to Loony Tunes, with an abundance of scenes with an anthropomorphized coyote being hurled at the ground from gravitational acceleration, giant rocks plummeting to a spot inevitably marked with an X, previously occupied by a member of the “accelerati incredibilus” family and soon to be a big squish mark containing the bodily remains of the previously mentioned Wile E. Coyote.
Despite having a very limited understanding of it, Gravity is a pretty amazing force, not just for decimating a infinitely resurrecting coyote, but for keeping our feet on the ground and our planet in just the right spot around our Sun. The force due to gravity has got a whole bag of tricks, and reaches across Universal distances. But one of its best tricks is how it acts like a lens, magnifying distant objects for astronomy.
Whoa, here’s something to think about. Maybe the Universe isn’t expanding at all. Maybe everything is actually just shrinking, so it looks like it’s expanding. Turns out, scientists have thought of this.
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Video Transcript
It’s tinfoil hat day again at The Guide To Space. There’s some people who would have you believe the Universe is expanding. They’re peddling this idea it all started with a bang, and that expansion is continuing and accelerating. Yet, they can’t tell us what force is causing this acceleration. Just “dark energy”, or some other JK Rowling-esque sounding thing. Otherwise known as the acceleration that shall not be named, and it shall be taught in the class which follows potions in 3rd period.
I propose to you, faithful viewer, an alternative to this expansionist conspiracy. What if distances are staying the same, and everything is in fact, shrinking? Are we destined to compress all the way down to the Microverse? Is it only a matter of time before our galaxy starts drinking its coffee from a thimble or perhaps sealed in a pendant hanging on Orion’s belt? So, could we tell if that’s actually what’s going on?
Representation of the timeline of the universe over 13.7 billion years, and the expansion in the universe that followed. Credit: NASA/WMAP Science Team.
Better get some scotch tape for the hats, kids. This one gets pretty rocky right out of the gate.
The first horrible and critical assumption here is that shrinking objects and an expanding universe would look exactly the same, which without magic or handwaving just isn’t the case. But you don’t have to take my word for it, we have science to punch holes in our Shrink-truther conspiracy.
Let’s start with distances. If we assumed the Earth and everything on it was getting smaller, we’d also be shrinking things like meter sticks. In the past they would have been larger. If everything was larger in the past, including the length of a meter, this means the speed of light would have appeared slower in the past. So was the speed of light slower in the past? I’m afraid it wasn’t, which really hobbles the shrinky-dink universe plot. But how do we know that?
The diagram shows the electromagnetic spectrum, the absorption of light by the Earth’s atmosphere and illustrates the astronomical assets that focus on specific wavelengths of light. ALMA at the Chilean site and with modern solid state electronics is able to overcome the limitations placed by the Earth’s atmosphere. (Credit: Wikimedia, T.Reyes)
You’ve probably seen spectral lines before or at least heard them referenced. Scientists use them to determine the chemical composition of materials. A changing speed of light would affect the spectral lines of distant objects, and because some people are just super smart and were able to do the math on this, we know that when we look at distant gas clouds we find the speed of light has changed no more than one part in a billion over the past 7 billion years.
Shrinking objects would also become more dense over time. This means that the universal constant of gravity should appear smaller in the past. Some have actually studied this, to determine whether it has changed over time, and they’ve also seen no change.
Artists illustration of the expansion of the Universe (Credit: NASA, Goddard Space Flight Center)
If objects in the Universe were shrinking, the Universe would actually be collapsing. If galaxies weren’t moving away from each other, their gravity would cause them to start falling toward each other. If they were shrinking, assuming their mass doesn’t change, their gravity would be just as strong, so shrinking wouldn’t stop their mutual attraction. A Universe of shrinking objects would look exactly opposite to what we observe.
So, good news. We’re pretty sure that objects, and us, and all other things in the Universe are not shrinking. We’re still not sure why anyone would name a thing Shrinky Dinks. Especially a craft toy marketed at children.
Think big. Really big. Like, cosmic big. How big can things in the Universe get? Is a galaxy big? What about a supercluster? What is the biggest thing in the Universe?
Our observable Universe is a sphere 96 billion light-years across, and the entire Universe might be infinite in size. Which is a hoarders dream walk-in closet space stuffed full of “things”. It’s loaded down with so much stuff, we’ve even given up naming things individually and now just spew out a list of letters and numbers to try and keep track of it all.
So, as is traditional, in a fit of adolescent OCD and one-upmanship reserved generally for things like tanks, planes and guns, we’re drawn to the question… What’s the biggest thing in the Universe. Well, 14 year old Fraser Cain, put down your copy of “Weapons and Warfare Volume 3” which you picked up at the dollar store as part of an incomplete set, as this is going to get a little tricky.
It all depends on what you mean by a “thing”. The biggest physical object is probably a star. The largest possible red giant star could be as big as 2,100 times the size our Sun. Placed inside our own Solar System, a monster star like this would extend out past the orbit of Saturn. That’s big, but we might be able to get even bigger if we’re willing to get past the idea that a “thing” has to be a homogeneous physical object.
Consider the regions around supermassive black holes. Within our own galaxy, things are pretty quiet, but around actively feeding black holes, there can be disks of material with such temperature and density that they act like the core of a star, fusing hydrogen into helium. Which, purely based on high volumetric density of pure awesome, I’m going to call a thing. An accretion disk around a quasar could be light days across, extending well past the orbit of Pluto and killing us all, if you dumped it in our Solar System.
If we’re going to be all philosophical about what constitutes a “thing” and you’re not all fussy about physical structure and just want a collection of material held together by gravity, then we can really can make some leaps and bounds in our “who’s got the biggest” measuring contest. Our own galaxy extends up to 120,000 light-years across.
There are much larger galaxies, ones that make the Milky Way look like that cat leash pendant from Men In Black 2. And ours is just one contained within a much larger cluster of galaxies known, rather unimaginatively, as the Local Group. Don’t let the centrist name fool you, this cluster contains around 50 galaxies and measures more than 10 million light-years across.
Partial map of the Local Group of galaxies. Credit: Planet Quest
And we’re just getting started. The Local Group is one part of the Virgo Supercluster. A massive galactic structure that measures 110 million light-years apart. In 2014, astronomers announced that the Virgo Supercluster is just one lobe of an even larger structure, beautifully known as Laniakea, or “Immeasurable heaven” in Hawaiian. The name originated from Nawa’a Napoleon, an associate professor of Hawaiian Language at Kapiolani Community College. It honors the Polynesian sailors using “heavenly knowledge” navigating the Pacific Ocean, reminding us that romance is still alive and well in space and astronomy. Laniakea is centered around the Great Attractor – a mysterious source of gravity drawing galaxies towards it.
I almost forgot about our size contest. So who’s got the biggest space thing? According to buzzkill Ethan Siegel from the Starts With a Bang blog, you can’t actually have a structure that’s as big as Laniakea, and call it a thing. The fine-print reality is that the expansion of the Universe is being accelerated by dark energy. These galaxies are being pushed apart by dark energy faster than gravity can pull them together. So they’d never be able to form into a single object given enough time.
In other words, the largest possible object is a collection of galaxies at the exact size where gravity is just strong enough to overcome the expansive force of dark energy. Beyond that, everything’s getting spread apart, and it’s for our purposes we’re actually going to draw a line and say it’s not quite right to call it a thing. Unless you’d suggest a giant expanse of nothing is a thing… but let’s save that for another episode.
So what do you think? Do you feel like it’s right to call superclusters like Laniakea “a structure”?
You know the quote, we’re made of stardust. Generation after generation of stars created the materials that make us up. How? And how many stars did it take?
Carl Sagan once said, “The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of star stuff.” To an average person, this might sound completely bananas. I feel it could easily be adopted into the same dirty realm as “My grandpappy wasn’t no gorilla”.
After all, if my teeth are made of stars, and my toothpaste supplier can be believed, why aren’t they brighter and whiter? If my bones are made of stars, shouldn’t I have this creepy inner glow like the aliens from Cocoon? Does this mean everything I eat is made of stars? And conversely, the waste products of my body then are also made of stars? Shouldn’t all this star business include some cool interstellar powers, like Nova? Also, shouldn’t my face be burning?
When the Big Bang happened, 13.8 billion years ago, the entire Universe was briefly the temperature and pressure of a star. And in this stellar furnace, atoms of hydrogen were fused together to make helium and heavier elements like lithium and a little bit of beryllium.
This all happened between 100 and 300 seconds after the Big Bang, and then the Universe wasn’t star-like enough for fusion to happen any more. It’s like someone set a microwave timer and cooked the heck of the whole business for 5 minutes. DING! Your Universe is done! All the other elements in the Universe, including the carbon in our bodies to the gold in our jewelry were manufactured inside of stars.
But how many stars did it take to make “us”? Main sequence stars, like our own Sun, create elements slowly, but surely within their cores. As we speak, the Sun is relentlessly churning hydrogen into helium. Once when it runs out of hydrogen, it’ll switch to crushing helium into carbon and oxygen. More massive stars keep going up the periodic table, making neon and magnesium, oxygen and silicon. But those elements aren’t in you. Once a regular star gets going, it’ll hang onto its elements forever with its intense gravity. Even after it dies and becomes a white dwarf.
White Dwarf Star
No, something needs to happen to get those elements out. That star needs to explode. The most massive stars, ones with dozens of times the mass of our Sun don’t know when to stop. They just keep on churning more and more massive elements, right on up the periodic table. They keep fusing and fusing until they reach iron in their cores. And as iron is the stellar equivalent of ash, fusion reactions no longer generate energy, and instead require energy. Without the fusion energy pushing against the force of gravity pulling everything inward, the massive star collapses in on itself, creating a neutron star or black hole, or detonating as a supernova.
It’s in this moment, a fraction of a second, when all the heavier elements are created. The gold, platinum, uranium and other rare elements that we find on Earth. All of them were created in supernovae in the past. The materials of everything around you was either created during the Big Bang or during a supernova detonation. Only supernovae “explode” and spread their material into the surrounding nebula. Our Solar System formed within a nebula of hydrogen that was enriched by multiple supernovae. Everything around you was pretty much made in a supernova.
These images taken by the Spitzer Space Telescope show the dust and gas concentrations around a supernova. Credit: NASA/JPL-Caltech
So how many? How many times has this cycle been repeated? We don’t know. Lots. There were the original stars that formed shortly after the Big Bang, and then successive generations of massive stars that formed in various nebulae. Astronomers are pretty sure it was a least 3 generations of supernovae, but there’s no way to know exactly.
Carl Sagan said you’re made of star-stuff. But actually you’re made up mostly of Big Bang stuff and generations of supernova stuff. Tasty tasty supernova stuff.
What’s your favorite supernova remnant? Tell us in the comments below.
