Universe Today Video

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.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.

The Universe is expanding, but how quickly is it expanding? How far away is everything getting from everything else? And how do we know any of this anyway?When astronomers talk about the expansion of the Universe, they usually express it in terms of the Hubble parameter. First introduced by Edwin Hubble when he demonstrated that more distant galaxies are moving away from us faster than closer ones.The best measurements for this parameter gives a value of about 68 km/s per megaparsec.Let’s recap. Hubble. Universe. Galaxies. Leaving. Further means faster. And then I said something that sounded like “blah blah Lando blah blah Kessel Run 68 km/s per megaparsec”. Which translates to if you have a galaxy 1 megaparsec away, that’s 3.3 million light years for those of you who haven’t seen Star Wars, it would be expanding away from us at a speed of 68 km/s. So, 1 megaparsec in distance means it’s racing away at 68 km/s.This is all because space is expanding everywhere in all places, and as a result distant galaxies appear to be expanding away from us faster than closer ones. There’s just more “space” to expand between us and them in the first place. Even better, our Universe was much more dense in the past, as a result the Hubble parameter hasn't always had the same value.There are two things affecting the Hubble parameter: dark energy, working to drive the Universe outwards, and matter, dark and regular flavor trying to hold it together. Pro tip: The matter side of this fight is currently losing.Earlier in the Universe, when the Hubble parameter was smaller, matter had a stronger influence due to its higher overall density. Today dark energy is dominant, thus the Hubble parameter is larger, and this is why we talk about the Universe not only expanding but accelerating.Our cosmos expands at about the rate at which space is expanding, and the speed at which objects expand away from us depends upon their distance. If you go far enough out, there is a distance at which objects are speeding away from us faster than the speed of light. As a result, it’s suspected that receding galaxies will cross a type of cosmological event horizon, where any evidence of their existence, not even light, would ever be able to reach us, no matter how far into the future you went.What do you think? Is there anything out there past that cosmological event horizon line waiting to surprise us?

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. Thanks to the general theory of relativity, we know that mass curves the space around it. The theory also predicted gravitational lensing, a side effect of light travelling along the curvature of space and time where light passing nearby a massive object is deflected slightly toward the mass.It was first observed by Arthur Eddington and Frank Watson Dyson in 1919 during a solar eclipse. The stars close to the Sun appeared slightly out of position, showing that the light from the stars was bent, and demonstrated the effect predicted. This means the light from a distant object, such as a quasar, could be deflected around a closer object such as a galaxy. This can focus the quasar’s light in our direction, making it appear brighter and larger. So gravitational lensing acts as a kind of magnifying glass for distant objects making them easier to observe.We can use the effect to peer deeper into the Universe than would otherwise be possible with our conventional telescopes. In fact, the most distant galaxies ever observed, ones seen just a few hundred million years after the Big Bang, were all discovered using gravitational lensing. Astronomers use gravitational microlensing to detect planets around other stars. The foreground star acts as a lens for a background star. As the star brightens up, you can detect further distortions which indicate there are planets. Even amateur telescopes are sensitive enough to spot them, and amateurs regularly help discover new planets. Unfortunately, these are one time events as this alignment happens only once.There’s a special situation known as an Einstein Ring, where a more distant galaxy is warped by a nearby galaxy into a complete circle. To date a few partial rings have been seen, but no perfect Einstein Ring has ever been spotted.Gravitational lensing also allows us to observe invisible things in our Universe. Dark matter doesn't emit or absorb light on its own, so we can’t observe it directly. We can’t take a photo and say “Hey look, dark matter!”. However, it does have mass, and that means it can gravitationally lens light originating behind it. So we've even used the effect of gravitational lensing to map out dark matter in the Universe.What about you? Where should we focus our gravitational lensing efforts to get a better look in the Universe? Tell us in the comments below.

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.Videos Suggested for You: 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?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?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.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.

If Dr. Who has taught us anything, it's that time is kind of crazy. And we're not just talking about time travel here, we're talking about regular old "now". Well, what "now" means depends on where you are and how fast you're moving.Videos Suggested for You: Video Transcript There are some topics that get a little frustrating in their pedantry, but can really draw attention to the grand scope and mechanics in our Universe. This is definitely one of them.We know looking through a telescope is like looking into the past, both out from and towards our Earth. We know if alien ships were looking at the Earth right this moment from distant star systems they’d could well be watching dinosaurs chomping on each other’s adorable little faces.So how do we know what’s actually going on right now in other parts of the Universe? No matter how close together, the real challenge of defining “now” simultaneously for two different spots in the Universe is that these points are always separated by a bit of distance. Since nothing can travel faster than light, it will always take a some time for an indicator that an event has “happened” to reach you.So, on the small scale. If your friend 3 meters away from you says “Enterprise was a terrible show” right “now”, it will still take about 10 nanoseconds for the light of your friend to reach you. It will take about 8 milliseconds for the sound of your friend’s voice to reach you. Shortly thereafter you’ll decide to slap your friend, because seriously who needs that kind of negativity. You might say that is close enough to be the same “now”. As in “I slapped my friend just now, because he said something stupid”.For how our brains perceive time, and the relative length of our lifespans, you probably can get away with it, because sure, that’s “now”. We can consider a moment to occupy a span to encompass all these events. Although, you shouldn't slap your friends. Even if they say mean things, and really didn't give it a chance. You’re lucky your friend won’t have to wait too long to hear an apology from you as milliseconds after you say you’re sorry, they’ll hear you. Which, for our purposes, would be “right now”.Over larger distances this doesn't quite work as well. If you looked up in the sky and saw Betelgeuse become a supernova, would you argue that it is happening now? Some people might say yes. Until you know about an event, you can’t say it is happening. So, “Hey look, that star is going supernova right now” is what your brain might think. You received an indicator the event is beginning to happen, which for our purposes indicates it just started “now”.Except, as one of our viewers, you’re way too smart for that. You would argue that since Betelgeuse is 640 light years away, the supernova actually happened 640 years ago, and it’s just taken that long for the light to reach us. We’re all good so far, as soon as I started talking about light years, you knew what was going on. It looks like it just happened now, but we’re aware that’s not the case. It happened before, we’re only aware it’s happening now.Here is where it gets weird. The most distant galaxy yet discovered is z8 GND 5296. It’s 3.4 billion light years away. If we happened to observe a supernova in that distant galaxy, when would we say it happened? Obviously it’s not “just now”.When the light we currently observe left that galaxy, it was about 3.4 billion light years away. So should we say it happened 3.4 billion years ago?Sure sounds reasonable based on our Betegeuse example. However, since our Universe has been expanding, it actually took the light 13.1 billion years to reach us.

Some times planets just head off into the mysterious Universe all on their own, without a star to orbit. How and why do planets go rogue like this?We’re accustomed to thinking about solar systems as places of order. All the planets orbit their parent star, everything is neatly arranged in ellipses and rings. Even the asteroid belt has division lines of dry and icy. Planets do what they’re told: orbit that star until the end of time. No Pluto, you may not go outside and play with the other planets. You’ll spend your lunch hour in detention with Haumea until we decide what we’re going to do with you for not cleaning up your play area.Some planets just can’t be held down. They’re the Jimmy Deans, the greasers, the Marlon Brandos, the Cool Hand Lukes. They break all the laws and play by their own set of rules. They’re a rolling stone, baby. To ask them to settle down would just be to deny their nature. So instead of orbiting a star, they go rogue and fly off into the Milky Way, possibly seeking fame, fortune and adventure, but keeping to the beat of their own drummer.A rogue planet is any planet that doesn't orbit a star. Instead of being a member of a solar system, it orbits the Milky Way on its own. Or in the case of really deviant planets, it’s been ejected out of the Milky Way entirely. Make no mistake, this is not a small condition affecting a few planets. It’s estimated that there are billions of rogue planets out there in the Milky Way.How does this happen? How can we get rogue planets? Is it the way they were raised? Something that happened in the way they were born? Some rogue planets started out as part of a solar system, and then something happened. Some event “kicked” them out into deep space. You could get a collision or near miss with another star, or even a black hole. As two stars pass one another, their gravitational interactions can cause all kinds of mayhem to a nice orderly orbital system. Planets can be kicked into higher or lower orbits, smashed into stars or flung out with an escape velocity that means they’ll never orbit their star again.Planets can also escape when their star disappears. Sounds impossible? Sometimes stars go out for cigarettes and just never come back. When a massive star detonates as a supernova, the force of the explosion can eject planets at tremendous velocities away from the former star, flinging those billiard balls all over the hall. But the vast majority of rogue planets probably formed early on in their solar systems. Things were rough and chaotic back then, with planets smashing into each other with all kinds of near misses. These interactions could bully out smaller neighbors with not so much as a nod. Jupiter, I’m looking at you.It’s also possible that planets could form as orphans, within a solar nebula, away from a star entirely. If a pocket of hydrogen collects together into a sphere, but it doesn't have enough mass to actually ignite as a star, it’s another type of rogue planet. We’ll just pretend these ones were raised by Nuns.What would it be like for these planets? Without the light from a star, these would be incredibly cold places. This isn't just sad metaphor. The outer layers, exposed to space would be as cold as interstellar space, just a handful of degrees above absolute zero.But deep down below the surface, there would still be leftover heat from their formation, so it’s possible that life could survive down there, kept alive within a warm cocoon.And who knows, maybe after billions of years, a rogue planet could get captured by a star again, and thawed out. It might get a second chance, or it could all end tragically, racing for pinks along the Devil’s elbow out past the Pillars of Creation. There are many ways that planets can go rogue, in fact, it’s possible that there are more starless planets in the Milky Way than there are stars.So what do you think? Should we set sail from the Sun,

I don’t want to freak you out, but you should be aware that there’s a gigantic galaxy with twice our mass headed right for us. Naw, I’m just kidding. I totally want to freak you out. The Andromeda galaxy is going to slam head first into the Milky Way like it doesn't even have its eyes on the road.Videos Suggested for You: Transcript I don’t want to freak you out, but you should be aware that there’s a gigantic galaxy with twice our mass headed right for us. Naw, I’m just kidding. I totally want to freak you out. The Andromeda galaxy is going to slam head first into the Milky Way like it doesn't even have its eyes on the road.This collision will tear the structure of our galaxy apart. The two galaxies will coalesce into a new, larger elliptical galaxy, and nothing will ever be the same again, including your insurance premiums. There’s absolutely nothing we can do about it. It’s like those “don’t text and drive commercials” where they stop time and people get out and have a conversation about their babies and make it clear that selfish murderous teenagers are really ruining everything for all of us all the time.And now that we know disaster is inbound, all we can do is ask WHY? Why this is even happening? Isn't the Universe expanding, with galaxies speeding away from us in all directions? Shouldn't Andromeda be getting further away, and not closer? What the hay, man!Here’s the thing, the vast majority of galaxies are travelling away from us at tremendous speed. This was the big discovery by Edwin Hubble in 1929. The further away a galaxy is, the faster it’s moving away from us. The most recent calculation by NASA in 2013 put this amount at 70.4 kilometers per second per megaparsec. At a billion light-years away, the expansion of the Universe is carrying galaxies away from us at 22,000 km/s, or about 7% of the speed of light. At 100 million light-years away, that speed is only 2,200 km/s.Which actually doesn't seem like all that much. Is that like Millenium Falcon fast or starship Enterprise Warp 10 fast? Andromeda is only 2.5 million light-years away. Which means that the expansion of the Universe is carrying it away at only 60 kilometers per second. This is clearly not fast enough for our purposes of not getting our living room stirred into the backyard pool. As the strength of gravity between the Milky Way and Andromeda is strong enough to overcome this expansive force. It’s like there’s an invisible gravity rope connecting the two galaxies together. Dragging us to our doom. Curse you, gravity doom rope!Andromeda is speeding towards us at 110 kilometers per second. Without the expansion of the Universe, I’m sure it would be faster and even more horrifying! It’s the same reason why the Solar System doesn't get torn apart. The expansion rate of the Universe is infinitesimally small at a local level. It’s only when you reach hundreds of millions of light-years does the expansion take over from gravity.You can imagine some sweet spot, where a galaxy is falling towards us exactly as fast as it’s being carried away by the expansion of the Universe. It would remain at roughly the same distance and then we can just be friends, and they don’t have to get all up in our biz. If Andromeda starts complaining about being friend-zoned, we’ll give them what-for and begin to re-evaluate our friendship with them, because seriously, no one has time for that.The discovery of dark energy in 1998 has made this even more complicated. Not only is the Universe expanding, but the speed of expansion is accelerating. Eventually distant galaxies will be moving faster away from us than the speed of light.

You've probably heard the trope about how aliens have been watching old episodes of "I Love Lucy" and might think these are our "historical documents". How far have our signals reached?Television transmissions expand outward from the Earth at the speed of light, and there’s a trope in science fiction that aliens have learned everything about humans by watching our television shows. If you’re 4 light-years away, you’re see the light from the Earth as it looked 4 years ago, and some of that light includes television transmissions, as radio waves are just another form of electromagnetism - it’s all just light.Humans began serious television service in the 1930s, and by the modern era, there were thousands of powerful transmitters pumping out electromagnetic radiation for all to see. So are aliens watching “I Love Lucy” or footage from World War II and believing it all to be part of our “Historical Documents”?The first radio broadcasts started in the early 1900s. At the time I’m recording this video, it’s late 2014, so those transmissions have escaped into space 114 years ago. This means our transmissions have reached a sphere of stars with a radius of 114 light-years.Are there other stars in that volume of space? Absolutely. It’s estimated that there are more than 14,000 stars within 100 light years of Earth. Most of those are tiny red dwarf stars, but there would be hundreds of sunlike stars.As we’re discovering, almost all of those stars will have planets, many of which will be Earthlike. It’s almost certain some of those stars will have planets in the habitable zone, and could have evolved life forms, technology and television sets and were able to learn of the Stealth Haze and the Mak’Tar chant of strength.Will the signals be powerful enough to stretch across the vast distances of space and reach another world so that many generations of aliens can hang their hopes that James Tiberius Kirk never visits their planet with his loose morals, questionably applied prime directive, irresistible charms and pants aflame with who knows what kinds of interstellar STIs?Here’s the problem. Broadcast towers transmit their signals outward in a sphere, which falls under the inverse square law. The strength of the signal decreases massively over distance. By the time you've gone a few light years, the signal is almost non-existent.Aliens could build a huge receiver, like the square kilometer array being built right now, but the signals they could receive from Earth would be a billion billion billion times weaker. Very hard to pick out from the background radiation. And by Grabthar's hammer, I assure you it’s only by focusing our transmissions and beaming them straight at another star do we stand a chance of alerting aliens of our presence. Which, like it or not, is something we've done. So there’s that.We’ve really been broadcasting our existence for hundreds of millions of years. The very presence of oxygen in the atmosphere of the Earth would tell any alien with a good enough telescope that there’s life here. Aliens could tell when we invented fire, when we developed steam technology, and what kinds of cars we like to drive, just by looking at our atmosphere. So don’t worry about our transmissions, the jig is up.What do you think? Is it a good idea to alert aliens to our presence? Should we get rid of all that oxygen in our atmosphere and keep a low profile?

Have you ever seen the beautiful auroral displays in the high latitudes? These are the Northern and Southern Lights. But what dark physics wizardry is going on to make this happen?If you live in the high latitudes, like Alaska, or New Zealand, you've probably had a chance to see an aurora. Here in Canada, we call them the Northern Lights or the Aurora Borealis, but the lucky folks in the far southern latitudes see them too. On a good night, you can see flickering sheets of light that dance across the night sky, producing an amazing display of colors. You can see green, red and even yellow and purple ghostly displays.So what causes the Northern Lights? They’re produced as our planet moves through the chemtrails emanating from the womp-rat sized exhaust ports of Planet X. Originating in the Bush-Cheney administration during a failed co-invasion attempt of the lizard people from the hollow part of the flat earth and aliens from John Carpenter’s THE THING. They cause diabetes, gluten sensitivity, itchy bun noodles and homeopathy and herald the coming of the Grand Nagus of MMA-UFC-ENTJ-LOL-WTF-BBQ. That is, if you believe everything you read on the internet.Auroras are in fact caused by interactions between energetic particles from the Sun and the Earth’s magnetic field. The Earth is filled with liquid metal, and it rotates inside turning our planet into a giant magnet. Invisible magnetic field lines travel from the Earth’s northern magnetic pole to its southern magnetic pole. This is why compasses point north, they’re following the field lines produced by this giant metallic spinning goo core. Or as I like to call it “The Planetary Shield Generator”, which should not be confused with the giant whirling metallic debris field orbiting the Earth which is our “Alien Invasion Shield”. Which you can learn about in another episode.So why would we need a Planetary Shield, you might ask? It is because we are perpetually under assault by our great enemy, the Sun. Our Sun is constantly releasing a flurry of energetic particles right at us. These particles are electrically charged and driven to Earth by the Solar Wind. When they encounter the Earth’s magnetic field, they’re forced into a spiral along the magnetic field lines. Eventually they collide with an oxygen or nitrogen atom in the Earth’s atmosphere and release photons of light.So, thanks to the spinning magnet goo core, our planetary shield converts these particles into beautiful night time displays. Although there can be auroras almost any night in the highest latitudes, we see the most brilliant auroral displays after large flares on the Sun. The most powerful flares blast a hail of particles that’s so intense, auroral displays can be seen at mid and even low-latitudes. It sounds dangerous, but we’re perfectly safe here, beneath our protective atmosphere and magnetic field.You might be amazed to know that auroral displays can even make sounds. People have reported crackling noises coming from the sky during an aurora. Even though the auroras themselves are at very high altitudes, the particle interactions can happen just a few hundred meters above the ground. People have reported hearing claps and crackles during an aurora, and this has been verified by microphones placed by scientists. If you could get high up into the atmosphere, I’m sure the sounds would be amazing.The interactions between the Sun and our planet are just another gift we get from the night sky. If you've never seen an aurora with your own eyes, you really need to add them to your bucket list. Organize a trip to northern Europe or Alaska and get a chance to see this amazing display of nature.Have you ever been lucky enough to see the Northern Lights? Tell us a story in the comments below.

Gamma ray bursts are the most energetic explosions in the Universe, outshining the rest of their entire galaxy for a moment. So, it stands to reason you wouldn't want to be close when one of these goes off.If comics have taught me anything, it’s that gamma powered superheroes and villains are some of the most formidable around.Coincidentally, Gamma Ray bursts, astronomers say, are the most powerful explosions in the Universe. In a split second, a star with many times the mass of our Sun collapses into a black hole, and its outer layers are ejected away from the core. Twin beams blast out of the star. They’re so bright we can see them for billions of light-years away. In a split second, a gamma ray burst can release more energy than the Sun will emit in its entire lifetime. It’s a super-supernova.You’re thinking “Heck, if the gamma exposure worked for Banner, surely a super-supernova will make me even more powerful than the Hulk.” That’s not exactly how this plays out.For any world caught within the death beam from a gamma ray burst, the effects are devastating. One side of the world is blasted with lethal levels of radiation. Our ozone layer would be depleted, or completely stripped away, and any life on that world would experience an extinction level event on the scale of the asteroid that wiped out the dinosaurs.Astronomers believe that gamma ray bursts might explain some of the mass extinctions that happened on Earth. The most devastating was probably one that occurred 450 million years ago causing the Ordovician–Silurian extinction event. Creatures that lived near the surface of the ocean were hit much harder than deep sea animals, and this evidence matches what would happen from a powerful gamma ray burst event. Considering that, are we in danger from a gamma ray burst and why didn’t we get at least one Tyrannosaurus Hulk out of the deal?There’s no question gamma ray bursts are terrifying. In fact, astronomers predict that the lethal destruction from a gamma ray burst would stretch for thousands of light years. So if a gamma ray burst went off within about 5000-8000 light years, we’d be in a world of trouble.Astronomers figure that gamma ray bursts happen about once every few hundred thousand years in a galaxy the size of the Milky Way. And although they can be devastating, you actually need to be pretty close to be affected. It has been calculated that every 5 million years or so, a gamma ray burst goes off close enough to affect life on Earth. In other words, there have been around 1,000 events since the Earth formed 4.6 billion years ago. So the odds of a nearby gamma ray burst aren’t zero, but they’re low enough that you really don’t have to worry about them. Unless you’re planning on living about 5 million years in some kind of gamma powered superbody.We might have evidence of a recent gamma ray burst that struck the Earth around the year 774. Tree rings from that year contain about 20 times the level of carbon-14 than normal. One theory is that a gamma ray burst from a star located within 13,000 light-years of Earth struck the planet 1,200 years ago, generating all that carbon-14.Clearly humanity survived without incident, but it shows that even if you’re halfway across the galaxy, a gamma ray burst can reach out and affect you. So don’t worry. The chances of a gamma ray burst hitting Earth are minimal. In fact, astronomers have observed all the nearby gamma ray burst candidates, and none seem to be close enough or oriented to point their death beams at our planet. You’ll need to worry about your exercise and diet after all.So what do you think? What existential crisis makes you most concerned, and how do gamma ray bursts compare?

It's been said that a single asteroid might be worth trillions of dollars in precious rare metals. Will we ever reach out and mine these space rocks? How hard could it be?Here on Earth, precious metals like gold and silver are getting harder to find. Geologists are developing more elaborate ways to get at the veins of precious metals beneath the surface of the Earth. And for the truly rare metals, like platinum and iridium, forget about it. All the platinum ever mined in the history of the world would fit inside my basement, and it’s not that big of a basement.There are asteroids out there, just floating past us, taunting us, containing mountains of precious minerals. There are iron-nickel asteroids made entirely of metal. Comets of water, dirt and organic materials, everything you’d need to make an orbital farm. Just a single 30-meter asteroid, like the recently discovered 2012 DA14, is worth $20 trillion dollars. Now, if you could just somehow get to it.Mining here on Earth is hard enough, but actually harvesting material from asteroids in the Solar System sounds almost impossible. But almost impossible, is still possible. With enough ingenuity and a few breakthroughs in spaceflight and robotics, plus some convenient hand waving for the sake of storytelling and there could be a future of asteroid mining ahead of us.If there are mineral rich asteroids that contain a large amount of precious elements, it just might be cost effective to deliver those elements back to Earth. $20 trillion dollars sure would help buy that space elevator you wanted for sci-fi Christmas. If we had Robotic harvesters extract the gold, platinum and iridium off the surface of the space rock and they could send return capsules to Earth.It would make even more sense to keep this stuff in space. Future spacecraft will need rocket fuel, hydrogen and oxygen, conveniently contained in water. If you could mine water ice off a comet or asteroid, you could create fuel depots across the Solar System.Miners could extract and concentrate other materials needed for spaceflight and return them to Earth orbit. There could eventually be an orbiting collection of everything you need to survive in space, all gathered together and conveniently located … in space.You might be surprised to know that getting to a nearby asteroid would require less energy than traveling to the Moon. Asteroids actually make better refueling stations than the Moon, and could serve as a waypoint to the other planets.There are a few companies working to mine asteroids right now. Planetary Resources and Deep Space Industries have both developed plans for robotic missions to find asteroid targets, analyze them up close, and even return samples to Earth for study.Within a few decades, they should have identified some ideal candidate asteroids for mining, and we get on with the work of mining with Solar System to support our further exploration. Perhaps then we’ll become a true spacefaring civilization, or just get conquered by an uprising of our sentient robotic miner drones.So, will this ever happen? Will we eventually mine asteroids to send material back to Earth and support the exploration of space? Who knows. Business and industry are drivers of innovation. If there’s profit to be made, somebody will figure out how to do it.What do you think? Do you envision a future career as an asteroid miner? Can we all be like Bruce Willis? Tell us in the comments below.Thanks for watching! Never miss an episode by clicking subscribe. Our Patreon community is the reason these shows happen. We’d like to thank: From Quarks to Quasars Dark Matter is the New Black and the rest of the members who support us in making great space and astronomy content. Members get advance access to episodes, extras, contests, and other shenanigans with Jay, myself and the rest of the team.Want to get in on the action? Click here.

Have you ever wondered how much water it would take to put out the Sun? It turns out, the Sun isn't on fire. So what would happen if you did try to hit the Sun with a tremendous amount of water?How much water would it take to extinguish the Sun? I recently saw this great question on Reddit, and I couldn't resist taking a crack at it: We know that the question doesn't make a lot of sense.A fire is a chemical reaction, where material releases heat as it oxidizes. If you take away oxygen from a fire, it goes out. But.. there’s no oxygen in space, it’s a vacuum. So, there’s not a whole lot of room for regular flavor water-extinguishable fire in space. You know this. How many times have we had to seal off the living quarters and open the bay doors to vent all the oxygen in the space because there was a fire in the cargo bay? We have to do that, like, all the time.Our wonderful Sun is something quite different. It’s a nuclear fusion reaction, converting hydrogen atoms into helium under the immense temperatures and pressures at its core. It doesn't need oxygen to keep producing energy. It’s already got its fuel baked in. All the Sun needs is our adoration, quiet, and yet ever present fear. Only if we constantly pray will it be happy and perhaps we’ll go another day where it doesn't hurl a giant chunk of itself at our smug little faces because it’s tired of our shenanigans.So, I’m still going to take a swing at this question… so let’s talk about what would happen if you did pour a tremendous amount of water on the Sun? Let’s say another Sun’s worth of H20. Conveniently, Hydrogen is what the Sun uses for fuel, so if you give the Sun more hydrogen, it should just get larger and hotter.Oxygen is one of the byproducts of fusion. Right now, our Sun is turning hydrogen into helium using the proton-proton fusion reaction. But there’s another type of reaction that happens in there called the carbon-nitrogen-oxygen reaction. As of right now, only 0.8% of the Sun’s fusion reactions proceed along this path.So if you fed the Sun more oxygen as part of the water, it would allow it to perform more of these fusion reactions too. For stars which are 1.3 times the mass of the Sun, this CNO reaction is the main way fusion is taking place. So, if we did dump a giant pile of water onto the Sun, we’d just be making Sun bigger and hotter.Conveniently, larger hotter stars burn for a shorter amount of time before they die. The largest, most massive stars only last a few million years and then they explode as supernovae. So, if you’re out to destroy the Sun, and you’re playing a really, really long game, this might actually be a viable route.I’m pretty sure that wasn't the intent though. Let’s say we just want to snuff out the Sun. Vsauce provides a strategy for this. If you could somehow blast your water at the Sun at high enough velocity, you might be able to tear it apart. If you can reduce the Sun’s mass, you can decrease the temperature and pressure in its core so that it can no longer support fusion reactions.I’m going to sum up. The Sun isn't on fire. There’s no amount of water you could add that would quench it, you’d just make it explode, but if you used firehoses that could spray water at nearly the speed of light, you could probably shut the thing off and eventually freeze us all, which is what I think you were hoping for in the first place.What do you think? What else could we do to snuff out the Sun?

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.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 expa...

Thanks to our powerful telescopes, there are so many places in the Universe we can see. But there are places hidden from us, and places that we'll never be able to see. We’re really lucky to live in our Universe with our particular laws of physics. At least, that’s what we keep telling ourselves. The laws of physics can be cruel and unforgiving, and should you try and cross them, they will crush you like a bug. Here at Universe Today, we embrace our Physics overlords and prefer to focus on the positive, the fact that light travels at the speed of light is really helpful. This allows us to look backwards in time as we look further out. Billions of light-years away, we can see what the Universe looked like billions of years ago. Physics is good. Physics knows what’s best. Thanks physics. And where the hand of physics gives, it can also take away. There are some parts of the Universe that we’ll never, ever be able to see. No matter what we do. They’ll always remain just out of reach. No matter how much we plead, in some sort of Kafka-esque nightmare, these rules do not appear to have conscience or room for appeal. As we look outward in the cosmos, we look backwards in time and at the very edge of our vision is the Cosmic Microwave Background Radiation. The point after the Big Bang where everything had cooled down enough so it was no longer opaque. Light could finally escape and travel through a transparent Universe. This happened about 300,000 years after the Big Bang. What happened before that is a mystery. We can calculate what the Universe was like, but we can’t actually look at it. Possibly, we just don’t have the right clearance levels. On the other end of the timeline, in the distant distant future. Assuming humans, or our Terry Gilliam inspired robot bodies are still around to observe the Universe, there will be a lot less to see. Distance is also out to rain on our sightseeing safari. The expansion of the Universe is accelerating, and galaxies are speeding away from each other faster and faster. Eventually, they’ll be moving away from us faster than the speed of light. When that happens, we’ll see the last few photons from those distant galaxies, redshifted into oblivion. And then, we won’t see any galaxies at all. Their light will never reach us and our skies will be eerily empty. Just don’t let physics hear a sad tone in your voice, we don’t want to spend another night in the “joy re-education camps” Currently, we can see a sphere of the Universe that measures 92 billion light-years across. Outside that sphere is more Universe, a hidden, censored Universe. Universe that we can’t see because the light hasn't reached us yet. Fortunately, every year that goes by, a little less Universe is redacted from the record, and the sphere we can observe gets bigger by one light-year. We can see a little more in all directions. Finally, let’s consider what’s inside the event horizon of a black hole. A place that you can’t look at, because the gravity is so strong that light itself can never escape it. So by definition, you can’t see what absorbs all its own light. Astronomers don’t know if black holes crunch down to a physical sphere and stop shrinking, or continue shrinking forever, getting smaller and smaller into infinity. Clearly, we can’t look there because we shouldn't be looking there. They’re terrible places. The possibility of shrinking forever gives me the heebies. And so, good news! The chocolate ration has been increased from 40 grams to 25 grams, and our physics overlords are good, can only do good, and always know what’s best for us. In fact, so good that gravity might actually provide us with a tool to “see” these hidden places, but only because “they” want us to. When black holes form, or massive objects smash into each other, or there are “Big Bangs”, these generate distortions in spacetime called gravitational waves. Like gravity itself,

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. 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. 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.