TRANSCRIPT: LHS 1140b Exoplanet Update for 04/19/2017

Yet another case of a seemingly habitable world orbiting an M type red dwarf has surfaced. Just 40 light-years away, a super earth exoplanet has been found that seems to have, at least on its face, the best chance of detecting earth-like habitability that we have yet seen.

Known as LHS 1140b, this planet has some significant differences with earth. For one, it's about 1.4 times the size our planet and thusly would have higher gravity. It's mass suggests that it's rocky like our inner planets, which favors complex life.

Planets within the habitability zones of red dwarves need to orbit very closely, LHS 1140b for example orbits so close that its year is only 25 days so it would probably be tidally locked to its star, and perhaps make it an eyeball world with a habitable twilight area as some models of Trappist - 1 and its planets suggest. See my videos on that system on this channel.

Yet, even at that distance, LHS 1140b still only receives about half as much light from its star as we do from ours. Still, that's enough to maintain liquid water, at least on parts of the planet. And, unlike stars such as Trappist -1 which are thought to have been extremely active in their youth for a long period of time and might have stripped their worlds of their atmospheres, LHS 1140 is thought to be a relatively stable, quiet star that had an active phase early in its life that lasted only 40 million years. Trappist - 1, by contrast, was more to the tune of a billion years of activity.

With the discovery of first Proxima B and then the Trappist - 1 system, exoplanets within the habitability zones of red dwarf stars is a very active area of study. This is because planets within those zones are easier to see if you're dealing with a red dwarf as opposed to brighter stars like our sun. You could say that there is a sweet spot between stars that are too hot and bright and stars that are too dim to be suitable for studying transiting exoplanet atmospheres.

But it goes deeper. It's not yet clear how habitable red dwarves are. Only observations of exoplanets orbiting them will tell. But they are by far the most common type of star in the galaxy. Calm, stable stars like our sun are much harder to come by and the habitability question of red dwarves will figure prominently in determining how common life in the universe is.

But studying exoplanet atmospheres is a tricky thing. There are actually quite a few more detections of potentially habitable planets in our galaxy that come from the Kepler spacecraft, but their atmospheres aren't easy to study due to them being very distant, at least as far as detecting gases associated with life are concerned.  

But even when exoplanets are close, it's still not easy. In the case of Proxima-B, for example, it was discovered through its gravitational effects on its star. Think of it tugging on the star and astronomers can detect that wobble and infer a surprising amount of information from that, that's how LHS 1140b's density was determined. But what Proxima B doesn't do is pass in front of its star within our line of sight, which makes studies of any atmosphere that may be present exceedingly difficult.

And another problem faces those wishing to study Trappist - 1. Looking for biosignatures in the atmospheres of its worlds is difficult because of the nature of the star itself. While it is a star, it's as small and cool as they get. That means it's dim, and that means it's hard to use it to look at spectra passing through planetary atmospheres to look for things like oxygen which, if found, could suggest that life is present.

This makes LHS 1140b an attractive candidate as a starting point of studying exoplanet atmospheres for signs of life. Since the planet has higher gravity, it can better hold onto an atmosphere. And, when you know the density of a planet, you can determine how tightly it holds onto that atmosphere.

Plus, since the star was only active for 40 million years in its youth before quieting down, that also favors habitability. And since that active period would have happened shortly after the formation of the system, even if the planet did lose its atmosphere it might have been replenished by way of gases and water released by a still molten surface. How much water might be present on such a world and how much ultraviolet light and radiation bathes the planet remains to be seen, though the star seems to spin slowly which bodes well.

So LHS 1140b is the top current candidate for scientist's to look at for biosignatures. And the good news is that they certainly are looking. The team studying the system, lead by Jason Dittmann of the Harvard-Smithsonian Center for Astrophysics, link to their press release in the description below, are actively studying it to pin down the conditions in which this planet exists. Using the Hubble Space Telescope and a whole array of ground-based telescopes later this year, they will try to see an atmosphere and figure out what it's like.

If oxygen is found, in the future, instruments such as the James Webb space telescope and the Giant Magellan telescope will allow scientists to determine if that's due to the presence of life.

Thanks for listening! I am futurist and science fiction author John Michael Godier currently recording the audio track for this video which I will soon do again for my other channel John Michael Godier II which is dedicated to science fiction, link in the description below and be sure to check out my books at your favorite online book retailer and subscribe to my channel for regular, in-depth explorations into the interesting, weird and unknown aspects of this amazing universe in which we live.

TRANSCRIPT: GJ 1132b Update for 04/06/17 Exoplanet Atmospheres

At first glance, this story might not seem to have much of a connection to the question of life in the universe, the planet I'm about to discuss is probably about as hostile and uninhabitable as they get, but in fact it answers a long-standing question about exoplanet atmospheres and just where they can exist. That, in turn, has implications for where life, at least as we know it here on earth, can arise.

GJ 1132b is an exoplanet discovered around a star located about 39 light years away from us. It's a small planet, just a bit larger than Earth and is thought to be rocky. It's been called a potential Venus twin due likely having a very high surface temperature similar to Venus, though it's probably even hotter. It was also thought to likely have some type of thick atmosphere, though the composition was unknown. This atmosphere has now been directly observed.

Scientists have observed the atmospheres of exoplanets before, though up until now it was limited to gas giants and planets much larger than earth. This is the first time they've directly observed a planet with an atmosphere that is roughly in earth's class as far as size, but the similarities end there.

John Southworth of Keele University in the UK and colleagues used the European Southern Observatory or ESO, a hotbed for exoplanet discoveries as of late, to confirm the size of the planet by studying it as it transited in front of its star. But they saw something else within the data. One of the wavelengths of light they were studying seemed to be blocked by an atmosphere of some type, though its composition isn't yet fully understood.

This has an important implication regarding stars that can have habitable planets in the universe. Stars fall into different classes, our own sun being a G type yellow dwarf. GJ 1132b's star is an M-type dwarf, by far the most common kind of star in the Milky Way, in fact Trappist - 1 is in that class. GJ 1132, the parent star of the planet, is a type of star that tends to be pretty active and, up until now, it was unclear if any planets orbiting very near such a star could hold onto their atmospheres. For our kind of life here on earth, obviously having an atmosphere is quite important.

GJ 1132b seemingly answers the question. Yes, planets orbiting close to at least some M type stars can hold onto atmospheres. That potentially opens up a huge amount of stars to the possibility of harboring earth-like planets. But as far as GJ 1132b is concerned, it's not earth-like at all.

But what might GJ 1132b's atmosphere look like? One hypothesis based on the data is that it might be largely made up of water vapor, basically a steam bath world, or a world high in methane. The planet is close to its star, so it would probably be tidally locked, always presenting the same face towards the star. That's about all that can be said though.

But in the future this world is set to be a priority for study, especially with the James Webb Space Telescope. Other than Venus, this is the first roughly earth-sized planet with an atmosphere that we can study. As the facts about the planet come out, it will become a planet that we can envision what it might be like better than most other exoplanets. Scientists should eventually be able to work out the planet's color, what sort of winds it has, and even what sunsets might look like on this world.

Thanks for listening! I am futurist and science fiction author John Michael Godier currently hard at work preparing content for the new channel and be sure to check out my books at your favorite online book retailer and subscribe to my channel for regular, in-depth explorations into the interesting, weird and unknown aspects of this amazing universe in which we live

Trappist - 1 Update for 04/10/17

This video is part of my continuing coverage of the Trappist - 1 system. This star system is known to harbor at least 7 roughly earth-sized planets, and may hold the potential for liquid water on at least one of them. For the back story on this system, see my previous videos on this channel.

Much new information has come to light about this system, so much so that I'm barely able to keep up with the veritable snowstorm of scientific papers that have been coming out. One thing that hasn't changed about this system though are the uncertainties surrounding it, and it will be a while before any sort of consensus can be made on what these worlds are really like.

One of the main uncertainties involved with Trappist - 1 was the role of the outermost seventh planet and how it relates to the inner planets and the orbital stability of the system as a whole. This is because in the initial observations that planet had only been observed to transit once in front of the star.

But, in a paper from March 12, Rodrigo Luger and colleagues report further observations done with the Kepler space telescope that have narrowed down this planet's orbit and suggest that Trappist - 1h, which is thought to be larger than Mars but smaller than earth, could harbor liquid water with the right atmosphere, which would be some mix of hydrogen, nitrogen and carbon dioxide and could thusly be habitable.

But that's a could be, as with most of the planets in this system. A big factor here is stability, and that's a question that's in flux. Planets without stable orbits aren't conducive to life, especially if they occasionally ram into each other. So, while it's not yet known just how stable this system is, it seems to be moving into more stable territory. A paper from this morning by E.V. Quintana and colleagues suggests that the presence and characteristics of the seventh planet actually serves to help stabilize the system according to their models.

Another issue that's recently come to light that affects the habitability of the Trappist planets comes from a paper by Peter Wheately and colleagues, links to all papers in the description below. They suggest that the environment that the Trappist planets orbit in would be one with very, very high ultraviolet radiation streaming from the star. UV does not favor life as we know it, and would put some constraints on what sorts of atmospheres these planets can have.

And there's a further problem, according to a paper by K. Vida and colleagues, the Trappist -1 star displays frequent solar flares. This could mean that the atmospheres of these planets, if they have them at all, are continuously altered by the star's actvity. That too disfavors life.

On the opposite side of things, another big hurdle as far as the potential for life at Trappist -1 was the age of this star system. The Luger and colleagues paper however lays out indications from the star itself that the system is actually significantly older than originally thought with an age of between 3 and 8 billion years. This favors the potential for life, our own sun is in that age range at 4.6 billion years-old and that's proven to be enough time to produce an advanced civilization.

Civilizations are always unlikely and there is no indication whatsoever of one being at Trappist -1. But it was still worth it for SETI to take a look, however. Using the Allen Telescope Array, Seth Shostak and his colleagues searched for radio signals emanating from this system and the surrounding area. They found nothing. But that doesn't close the door for life in general, and indeed, the lack of good atmospheres might not either.

These planets orbit very close to their star, in fact they all orbit Trappist - 1 closer than Mercury orbits our sun. They also are very close to each other, a routine sight on one of these worlds would be another planet passing by appearing larger than our moon does in our sky. This would create tidal heating and perhaps subsurface oceans in the grain of Europa might be possible.

Another thing about this system that stands out is that because these worlds are so close to each other, they would be prime territory for panspermia, meaning that if one planet evolved life it could have easily been seeded to the other planets and vice versa. Multiple abodes favor life long-term.

So what of future studies of these planets? With the advent of the James Webb Space Telescope on the horizon along with European Extremely Large Telescope, we should soon have the ability to study the atmospheres of these planets in some detail. As noted in a paper by O'Malley-James and Kaltenegger, scientists will want to look for gases like ozone, if you see that one then the ultraviolet light equation changes significantly and indeed, that would be a strong indicator of life.

And, as a note for the curious, the original team investigating this world were mainly Belgian. Belgium is famous for it's many beers and Trappist is perhaps the most famous of them leading some to wonder if this system was in fact named after a beer. As it turns out, technically no.

It's named after the TRAPPIST telescope at La Silla observatory in Chile, though the team is said to have toasted the discovery with said beer. But don't feel let down, the telescope itself is named after the beer. It is a backronym to highlight the Belgian origin of the project, and rumor has it that the planets themselves are all informally nicknamed by the team after various other Belgian beers.

Thanks for listening! I am futurist and science fiction author John Michael Godier and I would like to officially announce the launch of my second channel! It's called John Michael Godier II, how's that for imaginative youtube channel names, link in the description below. It's dedicated to science fiction and the science behind it and I have already uploaded a sampling of content to explore and be sure to check out my books at your favorite online book retailer and subscribe to my channel for regular, in-depth explorations into the interesting, weird and unknown aspects of this amazing universe in which we live

Transcript: Trappist - 1 Update 04-05-17

This is an update in my continuing coverage of the Trappist -1 system, a fascinating solar system that could host up to 7 roughly earth-sized planets where the conditions could be right for liquid water, and thus hold the potential for life. See my other videos on this channel for more back story.

When I was a kid sitting in grade school science classes in the 1980's, I remember two scientific consensuses that stick in my mind to this day. One was that even though we had never seen one, or indeed any evidence of one, exoplanets outside our solar system almost certainly existed. There was no reason why they shouldn't, all you need to form them is a sufficient amount of solid material around a star to coalesce into planets. And that clearly happened here, so unless rocks and dust were rare in the universe it was a good bet that it happened elsewhere.

That consensus turned out to be correct, in 1992 the existence of an exoplanet was confirmed and since those days we have discovered evidence of well over 3000 planets not located in our solar system scattered among a wide variety of stars in our galaxy.

The other consensus that I remember was that, at the time, there wasn't any particular reason to think that Earth was rare. Indeed, blue jewel worlds like our own could populate the universe to such an extent that there could be untold thousands of civilizations in our galaxy alone allowing for science fiction universes like Star Trek where the discovery and contact of such civilizations was a routine, and often unpleasant and tricky, occurrence.

After all, if exoplanets turned out to be common, then why not? What would be so special about Earth? On its face, would seem like only serendipity favored it. After all, it just happens to be a certain size located at a certain distance from its star. And out of the vast multitude of stars in our galaxy alone, surely there would be many analogues of earth that took advantage of that same kind of luck. But that consensus has changed.

We know now that many things have come together to make our planet the way it is. Atmospheric composition, orbital stability, the presence of a moon to help keep earth rotating on its axis, the stability of the sun, are just a few of the many factors that make this planet an abode where complex life could evolve. Earth is probably not common at all, in fact it now seems likely that it is an extremely rare kind of world that we won't encounter much as we explore our universe.

And that leads us to Trappist - 1. This is a star system full of could be's. We see evidence of at least seven worlds that appear to be of a similar size to earth. More, they cluster in close to their dim, small red dwarf sun in such a way that, at least a portion of them, might, depending on the specific conditions present on those worlds, be able to support liquid water. Where there is liquid water, there is the possibility of life as we know it. Again, after all, we know that happened here.

A new climate model, which is no doubt one of many to come, may give us a picture of what these worlds might be like and suggest which planet astronomers should take a look at first. Also, models like this, and models of what the spectra of the planets might be like, are important because as scientists collect the data on these worlds in future years they can then compare them to the models and see which ones fit best.

According to the new model by Eric Wolf of the University of Colorado, link to his paper in the description below, the best chance for liquid water on a planet in this system would be on Trappist -1e. Wolf looked at the three most likely planets for liquid water, Trappist -1 d, e and f. In the model, the other four planets of the system didn't even come close. The farther out planets in the system would be frozen solid and the inner planets would be too hot.

Wolf modeled a variety of possible atmospheres for these three candidate worlds. To do this, he assumed that water, in whatever form, was freely available in the system. This is a reasonable assumption, the planets are modeled to have formed farther out from the star where ices are likely to have been present and then the planets migrated closer after formation. From there, he modified a model originally intended to study Earth's climate to produce the most complex model of the Trappist - 1 system we so far have.

Now, modeling planetary climates is a tricky business. Earth especially. As a result, more models are needed for a consensus to be arrived at as to what's going on with these planets. But in Wolf's model out of the three most likely candidates, only Trappist - 1e made the grade for liquid water. Planet d is too close to the star, if it had liquid water, it would simply boil off into a thick water vapor atmosphere. That should cause a runaway greenhouse effect producing a planet perhaps similar to Venus.

Planet f has the opposite problem. It's too far from the star and any water on its surface would be frozen solid. Wolf found no combination of atmospheric gases which could keep it warm enough, even carbon dioxide would freeze out according to the model. Not so with Planet e, liquid water was predicted to be possible there. But would that planet be earth-like? Not likely.

The planets at Trappist - 1 are probably tidally locked, given their proximity to their star. This means that Trappist -1e would always present the same face towards its star, much like the moon is similarly tidally locked with earth and always shows us the same face. This would create an eyeball-like world where you would have liquid water at the point on the planet that received the most light from the star. The rest would be ice. How much of the planet is conducive to liquid water is unknown, it would depend on if the sunlight is striking an ocean or a dryer continental landscape, the content of the atmosphere and so on, but perhaps around 20 percent of the surface could be earthlike in temperature.

But, as we're seeing with our own solar system, earth-like worlds are not the exclusive domain of liquid water. There are a variety of conditions, such as those of Enceladus or Europa, that could allow for subsurface liquid water. While it will be a long time before we know if such things are possible in the Trappist - 1 system, we at least know that the possibility for one potentially habitable planet more in the grain of earth is on the table.

Thanks for listening! I am futurist and science fiction author John Michael Godier currently with an upcoming book, it's called Supermind and asks if our universe is really a computer simulation and be sure to check out my other books at your favorite online book retailer and subscribe to my channel for regular, in-depth explorations into the interesting, weird and unknown aspects of this amazing universe in which we live.    

Transcript: Can You Phone the Past? The Tachyonic Antitelephone

Theoretical physics is an unusual branch of science loaded with interesting thought experiments, concepts and hypothetical devices. You can find everything from cats being simultaneously alive and dead sealed in cardboard boxes awaiting observation to Albert Einstein himself branding quantum entanglement as "spooky" and hard to believe, which it sort of is.

But one of the most odd concepts in theoretical physics stems from Einstein's work. It's the concept of a type of particle called a tachyon, and while still hotly debated, some argue that they could exist.

While science fiction authors have made much use of the word tachyon, the hypothetical particles themselves are not currently part of the standard model of particle physics. We've never seen one, nor any indication that they might exist. It's merely that nature may allow for them to exist, and if they did exist they would exhibit some very strange characteristics.

One would be that they always travel faster than light. But it's worth noting that the speed of light really isn't quite the brick wall that it's made out to be. Popular perception tends to be that the speed of light is a sort of mythical universal speed limit that nothing can ever exceed. But in reality, it only applies to normal matter, and the reason that it does is pretty straightforward.

Whenever you push something that has mass, such as a rocket, it requires that you expend energy to get it going. The faster you go, the more energy you have to expend. This works on a sliding scale and as you approach the speed of light, it requires more and more energy to accelerate further until you reach a point, which is the speed of light, where you would need infinite energy to go any faster. But, you can't ever have infinite energy.

Something that doesn't have mass in the same sense as a rocket, such as a photon of light, propagates through the universe at the speed of light. But relativity doesn't rule out an exact opposite state of affairs, and that brings us back to the tachyons.

If they exist, they would not be able to slow down to the speed of light because that also would require infinite energy. Opposite to normal matter, the less energy a tachyon has, the faster it would travel. Add energy, and it would slow down. But it gets even stranger.

Within relativity, there is an effect called time dilation. This is one of the weirder properties of the universe, but it definitely exists. Space and time are somehow linked, leading to the term space-time. As a result of this, the faster you travel through space, the slower time ticks.

This is really a matter of acceleration. We tend to think of gravity as a pulling force, it drags us down. And it does, but a better way to state it is that gravity is an acceleration towards something. Big, massive objects create acceleration towards them in nearby objects. As such, when you accelerate your rocket in space, time slows down, but it also slows down the closer you get to a gravity source.

So even sitting still here on earth's surface, you are still feeling, as gravity,  an acceleration towards earth's center. This means that time is ticking slower for you than it is for the astronauts on the ISS because they are a bit further away from earth than you are.

While it may seem weird, we know that this is more than just a prediction by Albert Einstein. Time dilation has very real world implications. One of these is on the GPS system. For that system to work you need some serious precision in timing, on the level of nanoseconds.

Trouble is, if clocks here on earth are ticking slower than the clocks on the GPS satellites, then the timing errors would accumulate very rapidly. So, we have to adjust and compensate for time dilation to make the system work, and if we didn't it would take only about two minutes for the GPS system to begin giving false results and it would grow to be increasingly off by about 10 kilometers per day. Any time you use the GPS system, it is actively being adjusted for time dilation.

So, the faster you go the slower time ticks, but another reason that you can't go faster than light is because the speed of light also just happens to be the point at which time quote-unquote "stops". It's a bit more complicated than that really, but we'll leave that for future video. With the tachyons, given that they are traveling faster than light, they would see the same effect in reverse. In short, they would always travel backwards in time.

The existence of tachyons would have broad implications. If they could be used to transmit information, then you could send messages to the past. In 1907 Einstein advanced that faster-than-light communications would create a causality paradox. This is a violation of intuitive cause and effect, where cause does not lead to an effect, but the effect comes before the cause.

If you could communicate faster-than-light then you could call yourself, or telegraph the past as Einstein termed it, and give your past self stock market tips and get rich. This has been termed the tachyonic antitelephone. But that we don't seem to be getting many calls from the future could be telling as to whether all of this is possible, but the debate over it continues.

Now, scientists have looked for tachyons. If they're streaming at us from space, when you look for them they are predicted to look a lot like a cosmic ray, but unlike cosmic rays they would be expected to reach a detector on the ground before the particles produced by their entry in the atmosphere because they would be moving faster. This has not been observed suggesting that tachyons do not exist.

But there is a model that accounts for the absence of tachyons and remains consistent with relativity itself. It comes from the work of James Wheeler and Joseph Spencer, both of Utah State University. Without going too deeply in the abstractness of this model, they re-envisioned space and time as a pair of light cones. One cone is the past, the other is the future connected by the present.

The model is such that while relativity allows for tachyons to exist, the model does not and the possibility for them unequivocally disappears. Only years of debate within theoretical physics will a consensus on this be formed.

But, as often happens in theoretical physics, you end up with a whole other set of questions and oddness. This model also predicts something rather disturbing. It would mean that the universe is deterministic. That kind of a universe is uncertain because the universe appears really probabalistic and even random on the quantum level.

But, some in quantum mechanics have dissented for years about that. They have maintained that the randomness is only an illusion and have kept the idea of determinism alive. Trouble is, a deterministic universe has spooky implications of its own. It would mean that the future is already written and set in stone. In such a case, we would merely be actors following a pre-determined script.

Philosophers still debate what determinism means as far as existence, but another aspect of time dilation and relativity is that not only does time slow down for you as you go faster, relative to the world outside, your space ship is, in fact, time traveling into the future.

That might imply that the future is set in stone and fully deterministic. But in quantum mechanics, determinism continues to fall short. How the two seemingly valid views reconcile is still an unknown, but as Shakespeare once said "All the world's a stage", perhaps he was more right than he thought.

Thanks for listening! I am futurist and science fiction author John Michael Godier currently about to launch a second channel, more on that in the next episode and be sure to check out my books at your favorite online book retailer and subscribe to my channel for regular, in-depth explorations into the interesting, weird and unknown aspects of this amazing universe in which we live. 

Transcript: The End of the Milky Way Galaxy

On this channel, we often think in terms of geologic time rather than time as it is in relation to an average human lifespan. Here, we're more like rocks in our perception of time, or at least I am, thinking ahead billions of years. When trying to think in terms of ten trillion chess moves ahead, there is one, huge white elephant in the room as far as future events are concerned. That's the cosmologically semi-imminent death of the Milky Way Galaxy.

That's not as scary as it seems, a galaxy is really just an arrangement of stars that is subject to change, it doesn't really matter so much to the individual stars of that galaxy. But we often intuitively think of our Milky Way galaxy as something that will permanently spiral its way through the universe unaffected by the lives and deaths of the individual suns that make up its fabric.

But this is not the case, the great familiar barred spiral that is our galaxy has only about four billion years to live. And it's death will be as spectacular as things get, we're set to ram headlong into the great Andromeda galaxy! And there is almost certainly nothing we can do about it no matter how advanced we get in the intervening years.

And, if that's not bad enough, the Andromeda Galaxy is much, much bigger than the Milky Way. Our galaxy contains about 300 billion stars. Andromeda contains a trillion. So the merger will be more like a swallowing up of the Milky Way by Andromeda rather than the other way around.

More, M-31 as it is also known is already so close that you can see it with the naked eye as a greenish-blue smudge in the constellation of Andromeda. That's because it's close, in terms of how huge the universe is, at just 2.5 million light-years away. But, it's getting closer. Fast. As in 68 miles per second fast. The collision speeds involved here are nearly unfathomable.

But don't worry. Space is an unbelievably huge place and the distance between individual stars in galaxies are usually quite huge, barring solar systems with multiple stars already in them. So collisions between individual stars would be very unlikely during the event.

Think of it like this, if you shrink stars and space down to the size of golf balls for comparison, the average distance between stars even in the relatively dense galactic core would still be similar to two golf balls separated by about two miles or a bit over 3 kilometers. That leaves lots of room for stars to pass by each other without colliding. But they will affect each other through gravity.

Within the gravitational chaos, some stars will be ejected from the merging galaxies entirely to wander the darkness of intergalactic space alone until they burn out, but the bulk the two galaxy's stars will coalesce into a new galaxy. While no official name for the resulting galaxy has been adopted, the two current favorites are Milkdromeda and Milkomeda.

But Milkdromeda won't be a beautiful new super spiral galaxy, that structure will be a thing of the past, but rather it will be a generally featureless and ho hum elliptical or with some luck a disc type galaxy maybe with some remnant of spiral structure, a sad end for both galaxies.

But there is one exception to the highly unlikely collision rule. This one is highly likely. Each of the galaxies has at its core a supermassive black hole. In Milkdromeda, these two black holes will approach each other and eventually converge into a single, supermassive black hole. It's unclear what this might do, though possibilities include the creation of a quasar or active galactic nucleus.

So you may be asking yourself what of earth in this melee of impending galactic chaos? A model from 2006 doesn't bode well. As the supermassive black holes coalesce, the sun could get caught up in the gravitational upheaval of it all and is predicted to have a 12 percent chance of getting ejected, though that is subject to change, of course.

But don't worry, getting ejected would take millions of years and have little effect on the solar system. Plus, the increasing luminosity of the sun by that time will have long before boiled the oceans away and the planet will be caught up in a runaway greenhouse effect so bad that the surface may be completely molten awaiting the sun to eventually expand into a red giant and swallow it up.

Well ... unless we're still around and by that time are a galaxy spanning Kardeshev type III civilization with the ability to save earth and prevent the sun's ejection with stellar engines and such. In that case, we will have just gained a trillion new stars to colonize in our great Milkdromedan Empire ... well, unless someone else already has them. In which case, they will command the energy of over three times the amount of stars that we do. Not good.

Transcript: What Lies Between Galaxies? Ejected Stars, Rogue Planets and Exotic Matter

We often view intergalactic space as a no man's land of empty space-time. And, it mostly is, about the most you'll find at most points within it are diffuse hydrogen atoms passing by. But there are some objects wandering the lonely reaches of intergalactic space, including stars and planets. And, it's just possible that there may even be somewhere in this universe an isolated civilization living amongst the black expanses.

One kind of object you might find wandering the space between thegalaxies are ejected stars, often called rogue stars. These are stars that presumably formed inside galaxies and then were ejected out. There are two mechanisms by which this is thought to happen. The first is during the gravitational chaos that occurs when two galaxies collide and the second is when a multiple star system gets too close to a black hole. One member of such a system would get sucked into the black hole, whereas the other or others would be flung out into space. There it becomes something known as a hypervelocity star.

Hypervelocity stars are just that, stars moving at very fast speed, and that can be enough to escape the gravity of their parent galaxy. But what's staggering about rogue stars is how many of them there apparently are. In 2010 and 12 an experiment called the Cosmic Infrared Background Experiment was launched using sounding rockets. The experiment found a strange glow coming from intergalactic space that could not originate from other galaxies.

The best explanation was rogue stars. But the sheer amount of light that was detected suggests that as much as half of all stars in the universe are wandering in intergalactic space. This is interesting because there is a mystery in particle physics called the "missing baryon problem".

Baryons are the particles that make up ordinary matter, a general term for protons, neutrons, etc. Most models of the early universe suggest that there should be way more baryons than there appear to be. But, if half of all stars are wandering intergalactic space, then that could go a long way in helping to account for the missing baryons.

But it likely wouldn't just be stars wandering intergalactic space. They might well take their planets with them ... and any life that might living on those planets. Passing so near a black hole isn't going to be good for life, but if it arises after the ejection then perhaps intergalactic space is teeming with life. Perhaps even civilizations exist out there completely unassociated with galaxies.

There is actually one factor that might favor such life. Most galactic stars reside in high radiation environments hostile to life, such as near a galactic core or in a star cluster. The close proximity to other stars in this case is bad for life, planets near the galactic core would be repeatedly sterilized by close supernovas. But the further you get from the core, out into the spiral arms of the galaxy and beyond, the potential for life grows.

But, there would also be rogue planets traveling without a star in intergalactic space. Similar to stars, these planets would be thrown clear of their parent galaxy through gravitational encounters. We may never see one of these, it would be incredibly hard to spot such a thing in deep space, but they likely exist.

And there are even models where these kinds of worlds can harbor liquid water and life if the planet has a way of keeping warm, such as nuclear decay in the core. This might create an ice shell world, similar to Europa or Enceladus. Or, if you add a thick hydrogen atmosphere, you could have surface liquid water and who knows what else.

One last kind of object that may lie in between the galaxies is very different from stars and planets. It's a hypothetical form of exotic matter that would exhibit negative mass. We're still uncertain whether this kind of matter exists in nature, or for that matter if we could somehow synthesize it. But this form of matter is thought to be possible only in that it's mathematically sound and does not violate the laws of conservation of energy or momentum, but it may violate relativity.

That it could violate relativity in a kind of loophole features prominently when you hear technological theorists talk about creating artificial wormholes, traversing black holes and building alcubierre drives to go faster than light. Most models of these potential future technologies all require this kind of exotic matter to exist.

Whether we can make this stuff is likely not going to be cleared up any time soon. We don't have a complete enough view of gravity, all the current theories fall short and we really need a unified theory of everything essentially. That also happens to be one of the greatest mysteries in modern physics, something even Einstein couldn't figure out. But we need it to answer the questions surrounding negative mass. But, if such a material could exist. What would it be like?

It would be extremely strange indeed. A normal object might weigh 5 kilograms on earth. But an object with negative mass would weigh negative 5 kilograms. Such an object would be expected to be repelled by gravity, in other words it would have the property of anti-gravity, and would fall upwards. Another odd expected effect of exotic negative mass matter is that when you push on it, it would push back. Moving furniture made of this material would be beyond difficult.

If there was some mechanism for this material to somehow have been created in the big bang, which is a huge if, it might well have been repelled by the galaxies completely and potentially lurks in deep space at points between them.

Thanks for listening! I am futurist and science fiction author John Michael Godier and if you would like to help support the channel, check out my Patreon page, link in the description below or check out my books at your favorite online book retailer and subscribe to my channel for regular, in-depth explorations into the interesting, weird and unknown aspects of this amazing universe in which we live.