TRANSCRIPT: The Great Meteor Procession of 1913

On February 9, 1913 an extraordinary and unique phenomenon was observed by multiple witnesses across Canada, the US and the island of Bermuda. Known as the Great Meteor Procession, this event seems to suggest that Earth once had, at least for a time, a second, small natural satellite. Think about that, that would mean that up until 1913 Earth technically had two natural moons.

Over a hundred reports exist of this phenomenon and what they indicate is that between 40 and 60 very slow moving fireballs arranged in groups moving in what appeared to be an identical path crossed the sky over the course of several minutes. This would be unusual for a normal meteorite, those tend to be lone wolves. It would be less unusual for a meteor shower, though those tend to involve dust grains and the apparent size of these fireballs would be more consistent with sizeable meteorites.

Meteor showers also tend to be fairly predictable events. They happen at the same time each year as earth passes through debris field left in the trail of comets that have crossed our orbit at some point in the past. Meteor showers also exhibit something called a radiant, this is a point in the sky where meteors, if you trace them backwards, appear to originate.

Astronomer Clarence Chant determined from the reports that The Great Meteor Procession did not have a radiant, and instead seems to have followed a great circle trajectory. There are thought to be two possible reasons for this. The parent object might have encountered earth before, grazed the atmosphere at a shallow angle and skipped back out into space. This is not unheard of, a rather large fireball was witnessed doing just that over western North America in 1972. Once back in space it might have broken up into pieces setting up for the multiple fire balls observed when it encountered earth again and was drawn in.

The second possibility is that whatever was the source for the meteors was formerly in orbit of earth. Now, bodies in the solar system, including earth, can capture other objects such as asteroids. Quite a few of the smaller moons in the outer solar system are believed to be just that, captured asteroids. They can eventually end up in stable orbits if the conditions are right, or they can orbit for a time in a decaying orbit. The latter may have been what happened here.

But there's another possibility and while it's sort of one of those old, dusty theories within space science that not a lot of people remember it was at least intriguing at the time. Astronomer John O'Keefe proposed that instead the material that made up the fireballs was instead a remnant of a ring system Earth might have had at one time, similar to Saturn.

This ring system would have been produced by the action of lunar volcanos long ago when they were still active, which relates to another theory of O'Keefe's that tektites, a group of natural glasses that show clear evidence of once having flown aerodynamically through the atmosphere, originated on the moon. His main evidence for this was a curious lack of water in tektites, internally they are very dry for something that originated on earth.

The theory was given serious consideration by science at one time. However subsequent studies of tektites have shown that they are most likely generated from earth rock melted during crater-forming asteroid impacts. The evidence for this has accumulated and is now pretty convincing but it doesn't really answer O'Keefe's ring theory.

Might the moon early in its history have sprayed materials far enough out into space to form a planetary ring system around earth? There really isn't much evidence for it unfortunately, other than potentially the Great Meteor Procession. And with that, no associated meteorites were ever found so we may never know the origins of this event. But it's at least fun to imagine planet earth with a second tiny moon, or even a ring long ago in the past. 

Thanks for listening! I am futurist and science fiction author John Michael Godier currently plugging my second channel. It's dedicated to science fiction and the science behind it and in a not-so-creative frenzy one night I named it John Michael Godier II, 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: Detecting Alien Stellar Engines

The universe can be a chaotic place where galaxies collide and stars get ejected to wander the intergalactic universe unassociated with their parent galaxy. If this situation were to happen to an inhabited star system, it might not be desirable to be ejected, or likewise if alien astronomers calculated a high likelihood that their star might be eaten by a black hole in a few million years, they might choose to construct a monumental, but hypothetically possible, megastructure that can actually move their star.

Moving a star requires a variant of the Dyson shell concept called a Shkadov drive, or class A stellar engine. It's a surprisingly straightforward idea originally put forth in 1987 by Dr. Leonid Shkadov. The idea is to build an enormous spherical mirror to reflect the radiation pressure of a star in a different direction. This would have the effect of creating thrust and would propel the star in whatever direction the alien race wished it to go. As the star moved, it would carry its planets with it just as the sun does now with our planets as it travels through the galaxy.

The problem with this idea is that the thrust would be very slight and moving a sun-like star any large distance would take millions of years so it's difficult to envision that too many of these things get built out there in the universe. But it is possible, and there is room for other scenarios where a civilization might build such a thing to move a star just a small distance if that's what they happened to need. Or, if you have a civilization that's billions of years old and very forward thinking, they might not blink an eye at projects that take millions of years to complete.

So the question is, if there are civilizations building Shkadov drives, would we be able to detect them? Just such a method was put forth in a paper, link in the description below, by Dr. Duncan Forgan of the University of Edinburgh in 2013. It's worth noting that one of the main ways we detect exoplanets is by looking at the light curves of their stars as they pass in front of it and block light.

In other words, the data needed to detect a Shkadov drive is being taken anyway in the course of finding exoplanets and studying stars. It's more a matter of someone noticing something odd in those light curves, which is how Boyajian's star was identified. Now there are issues that Forgan points out, determining if a light curve indeed indicates the presence of a Shkadov drive could be complicated by other things in the light curve, such as the presence sun spots, so much observation would be needed to confirm such a thing.

Forgan also points out that while the chances of finding a star with a Shkadov thruster are exceedingly low but with all the data that's available scientists looking for other things should be aware of strange signatures in light curves that could indicate the presence of a Shkadov drive and anyone wishing to specifically look for them could do so at low cost from already available data.

So add one more way that we might detect an alien civilization independently of radio astronomy. I think this is one of the more unlikely scenarios, I can't imagine this type of megastructure would be very common, but astronomers see all sorts of interesting things in light curves so some day in the future who knows?

Thanks for listening! I am futurist and science fiction author John Michael Godier and if you'd 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.

TRANSCRIPT: The Zoo Hypothesis

The human race has looked out into the night sky for decades with our radio telescopes hoping to find signs of life. And while that search is ongoing, we have yet to see anything. For all intents and purposes, our universe appears quiet and uninhabited by other technologically advanced civilizations.

This could change at any moment, all we need to do is discover evidence of one other sentient species to answer many of our questions about life in the universe, but until that happens we must entertain other possibilities to explain this apparent lack of intelligent life.

One of the possibilities that we face is that intelligent alien races do not advertise themselves, and indeed may hide their existence from us. Known as the zoo hypothesis, it is one of the plethora of hypotheses that offer answers to the Fermi Paradox. It also happens to be among the spookiest.

The Fermi Paradox, formulated by physicists Enrico Fermi and Michael Hart, is very simple. There are billions of stable stars in our universe, and many of them are far older than our own. There is also a high probability that some of these stars host earth-like planets, a notion that has only been strengthened in recent years by the discovery of numerous exoplanets. Likewise, many of those are going to be far older than earth.

Some of those planets would, presumably, develop life like ours that eventually achieves intelligence. Here I have a sticking point, in my opinion I think that ultimately we may well find that microbial life is common in the universe, complex life like our plants and animals scarce, and intelligent life very rare. But I digress. Assuming that civilizations are relatively common then some of those will develop interstellar travel.

Here I have another sticking point. I'm not sure that an advanced civilization would care about interstellar travel. This relates to Simulation Theory, the notion that our universe is a computer simulation of some sort. I cover that theory in my video "Is the Universe real? Or is it a Computer Simulation?" and whether it's actually the case is anyone's guess, though it does appear to be scientifically testable.

But let's say the universe is a computer simulation as a thought experiment. If a civilization concluded that it is a simulation, then they may also conclude that there is no point to messing around with the universe. In such a nihilistic scenario, why not center your society on pleasure and descend into virtual reality utopias that are better than our universe? Think about The Matrix, only as a utopia, though I suppose Agent Smith had a point when he said in the films that they actually did initially try to create a utopia but no one was happy.

But, it's worth noting that we ourselves are striving for interplanetary exploration and eventually interstellar travel. Our behavior is all we can study for now, and that does count for something. Given that habitable planets exist, and they eventually become inhabited and may have done so long before earth did, and those inhabitants eventually spread out into the universe, then the Fermi Paradox notes that the entire galaxy can be explored at sub-light speeds in only a few million years. So why don't we see evidence of alien civilizations everywhere?

This brings us to the Zoo Hypothesis. The idea here is that alien civilizations hide themselves from us, either permanently or will some day reveal themselves and make contact when we've reached a sufficient level of technological and social development.

This may make sense. If the universe is a hostile place full of aggressive species, and your basic nature would be aggressive in some way if you're out boldly exploring the galaxy, then perhaps it's safer to hide and not contact anyone. In this scenario, advanced civilizations simply play it safe and do not interact with one another other than perhaps clandestine interstellar spy missions.

Or a civilization may find value in galactic diversity and not contact anyone so that they may simply study young civilizations and their natural development. This is something we ourselves do, there are still to this day uncontacted stone age tribes on our world and we take care to preserve that both for their own safety and ethical concerns about first contact, which has seldom gone well in the past.

But, you also have to ask a question here. If advanced civilizations are common and hiding their existence from lesser civilizations, then surely at least one of those advanced species would break the trend and show themselves. If they are common, then they must all be hiding and that would imply that somehow everybody out there is in agreement to hide. How does that work?

Now, this is pure speculation, but say a single civilization developed in the Milky Way long before any others. Even a billion years or longer before anyone else is possible. Say they colonized the entire galaxy, but hide their existence until a civilization they're watching matures. As other civilizations mature and meet this ancient civilization, the old ones may impart their wisdom of hiding to all civilizations in the galaxy. As a result, developing civilizations think they are alone, until one day they find out that they are not.

While an interesting idea and I make this video as merely food for thought, I still suspect that intelligence is simply rare, and when it does develop it takes time and a lot of chance. Finding evidence of such a rare civilization is like searching for a needle in a haystack for SETI and that some day, perhaps sooner rather than later, we will wake up to a changed world where we know unequivocally that we are not alone.

Thanks for listening! I am futurist and science fiction author John Michael Godier currently issuing a rebuttal to those that think I'm a robotic voice simulator. Not quite, but close. It's more like The Matrix, Mr. Anderson.

Just kidding, I'm really just a vulcan 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: Water Worlds, Desert Planets and ... Titan

One of the many questions that I wonder about is how rare Earth actually is.  Over the years, the consensus on that question has evolved somewhat from earth not being particularly special in the universe, perhaps even outright pedestrian, to earth looking increasingly special and rare with many factors playing into its habitability and ability to support the evolution of a technological species.

A new paper, link in the description below, authored by Fergus Simpson of the University of Barcelona may help shed some light on this question. This paper details an interesting prediction made by S. F. Dermott and Carl Sagan in 1995. At the time, it was thought that Saturn's moon Titan was likely to harbor hydrocarbons in liquid form. Just how much liquid would be present was open for debate and it ranged from vast oceans to Dermott and Sagan's idea that it wouldn't be anywhere near that extensive.

They predicted that if such oceans were present on Titan, its orbit would have been circularized by the action of tidal forces. That seemingly turned out to be correct, we know now that Titan's surface liquids are confined to a relatively sparse group of lakes. On the other end of the scale, we have Enceladus and Europa where there are strong indicators of deep subsurface liquid oceans, meaning that these two bodies are water worlds coated with a layer of ice with no known land.

The paper details that, statistically speaking, the division between land and ocean on a planet should be asymmetric. This implies that habitable exoplanets are either likely to either be water worlds where the surface is mostly, or entirely, covered in ocean or desert worlds where liquid water is present but scarce. Earth is the odd planet out given that we have a good amount of ocean but also lots of land.

Examples from science fiction of worlds like these would be dry, arid Tatooine from Star Wars or Thalassa from Arthur Clarke's novel "Songs of Distant Earth" which was a water world with a few human-inhabited islands, which may be the more common of the two in the universe.

While this does not preclude life arising on either water worlds or desert worlds, it does affect whether a technological civilization can arise. I've said in past videos that it would be exceedingly difficult for dolphins to master fire and smelt metal, regardless of their level of intelligence. On a water world, there may well be intelligence, but it might be locked in by its physiology perhaps awaiting direct contact with an alien species to liberate them from their world.

Now, much study of exoplanets will be needed to confirm or refute this paper, as Paul Gilster on his blog Centauri Dreams notes, we don't really yet have a complete picture of water delivery in the early solar system and that could affect the abundance of earth-like distributions of water within habitable zones.

Which brings me back to thoughts of strange Titan. It too is thought to have a subsurface very salty liquid water and ammonia ocean making it a sort of hybrid between a dry world and an ocean world. It may even harbor life, potentially several flavors of it in fact, one type on the surface, and another in the ocean. And it has another odd distinction, there will be a period 5 billion years from now where the sun will expand into a red giant. For a time during this period, its thought that Titan will be warm and become habitable and earth-like for a few hundred million years.

Will we some day retreat there to avoid the fury of the reddening sun and Earth's armageddon? Or will we be long gone and someone or something else arises on that little world? I find that future fun to ponder.

Thanks for listening! I am futurist and science fiction author John Michael Godier do check out my patreon page, 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: Are We the First Technological Civilization in the Solar System?

Digging through scientific papers as I do to research the content featured on this channel is something very much like hunting for Easter eggs. I would never call any scientific work mundane, any work done by scientists helps to advance our understanding of our world around us, but I might say that most subjects one sees in scientific papers just would not make for good YouTube videos unless done by a creator far better than I.

But several times a week I find papers, or easter eggs if you will, that excite me and then I go make videos on them. Occasionally, however, I will read a paper that absolutely blows my mind. That definitely happened this morning.

This paper is entitled "Prior Indigenous Technological Species" and was authored by Dr. Jason T. Wright of the Department of Astronomy and Astrophysics and Center for Exoplanets and Habitable Worlds at Pennsylvania State University, link to the paper in the description below. It's a good read folks.

But first some back story. It might surprise you, but it is fully scientific to consider the possibility of alien life having visited our solar system in the past. Carl Sagan and I.F. Schklovskii pointed this out in their book "Intelligent Life in the Universe" in 1966. This is independent of the question of whether the human race has ever interacted with an alien race. I have no problems with those that have concluded otherwise, but I have personally seen no compelling evidence that would lead me to conclude that we have. I have only seen material that leads me to more questions.

But the universe is a very old place, certainly old enough for other technological civilizations to have arisen long before ours did. It's also sufficiently old enough for an ancient civilization to have explored the galaxy end to end without exceeding the speed of light. Earth too, is sufficiently old enough to have been explored at some point in the distant past.

And, it's also fully within the realm of solid science to look for evidence of that as part of SETI operations, and indeed I've made several videos on this channel on the possibility of Bracewell or von Neumann probes hidden somewhere in the solar system. The tough question though is how likely is it that such a thing might exist?

This subject was tackled in a 2011 paper by Jacob Haqq-Misra and Ravi Kumar Kopparapu entitled "On the Likelihood of Non-Terrestrial Artifacts in the Solar System", link to the paper in the description below. They concluded that we simply have not explored our solar system thoroughly enough yet to detect such probes, if they exist, and that we should probably keep our eyes open for them just in case.

Dr. Wright in his new paper takes an interesting approach to the question of artifacts of other civilizations present in our solar system. He points out that while astrobiologists focus on searching for present or past evidence of simple life in our solar system, it may well be the case that artifacts of advanced civilizations are easier to find. And, going further, he suggests that the origin of such an artifact does not necessarily need to be another star system, but could be the solar system itself.

It is possible that advanced civilizations may have developed in the past on Earth, or even Mars or Venus which are thought to have once been earth-like. But Earth and Venus are geologically active worlds that renew their surfaces, so any evidence of an ancient civilizations is likely to be long gone on these planets. But you might find evidence of them on less active worlds like Mars or the Moon. Another possibility is that we might find an asteroid that was clearly mined at some point, perhaps by a von Neumann probe passing through.

Dr. Wright points out though that if we do find evidence, which we currently have absolutely none that stands up to scrutiny, then you must consider that the origin might not be another star system, but instead may be more likely to have originated from our own star system, especially considering that Earth would be a sort of elephant in the room since life has clearly arisen here.

While I consider it unlikely that there were ever precursor civilizations in our solar system, it is possible. And it's also possible that some day in the distant future others, perhaps from some formerly frozen moon made habitable by the brightening sun, might find evidence of us.

Thanks for listening! I am futurist and science fiction author John Michael Godier currently with a new book in the works, it's called Supermind and a 5000 word excerpt is up at Amazon Kindle Scout, link in the description below, check it out and if you like it give it a nomination! 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: Life on Jupiter?

Jupiter, at first glance, is perhaps the last place you would expect to find life. It's after all a roiling, hot gas giant. But it might surprise you that the gas giant itself has, at least in the past, been considered a possible home for life. And not just microbial life, but complex life. And while it's a long shot, it's not ruled out that something could inhabit the upper reaches of its atmosphere.

Jupiter is a generally misunderstood world. It's usually thought of as a huge ball of gas. But in reality, it's much more complicated than that. If you descend into Jupiter's atmosphere, you will first find a turbulent upper layer made up of a mix of gases, mostly hydrogen and helium. The further you go down, the hotter it will get due to the high pressures of the interior. At about 1000 kilometers below the top of the cloud deck you transition to one of the stranger natural substances thought to exist in our solar system. You would find metallic hydrogen.

Under the extremely high pressures of Jupiter's atmosphere hydrogen would be compressed into a soup of nuclei and electrons that exist in an ambiguous state that wouldn't have a clear boundary between a gas and a liquid. While metallic hydrogen is described as a liquid, it's a bit different than any other. It's better to think of the hydrogen as simply getting denser the deeper you go rather than use labels. Beyond that thick layer at the heart of the planet, it's thought you would find a core.

Not a lot is known about this core, but it's probably made of rock and metal just like the inner planets. It's not yet known if it's solid or completely molten or some mix of the two. Planetary cores are generally hard to study, and Jupiter's is among the hardest. But how could such an alien and strange environment such as Jupiter support any kind of life? The answer is in the conditions of the upper atmosphere.

In 1976, Carl Sagan and Edwin Salpeter released a paper, citation in the description below, in which they suggested that ammonia-based life of some kind might exist in the atmosphere of Jupiter. They envisioned three hypothetical kinds of animal that might live there which they termed sinkers, floaters and hunters. In particular, the floaters were envisioned as enormous gas bags, perhaps kilometers across and visible from orbit that suspended themselves in the atmosphere using helium.

Now, we have never seen floaters with any of our probes to Jupiter and this was a very speculative paper based on thinking deriving from what we know about our own oceans and life there. No such indications have ever surfaced that such a thing could really exist on Jupiter. But what does exist at Jupiter is the possibility of some interesting life related chemistry. The chemicals in the upper atmosphere of Jupiter do include water, ammonia and methane along with plenty of hydrogen in gas form.

These just happen to be the gases used in an interesting experiment done in 1952 by Stanley Miller and Harold Urey. They wanted to recreate the conditions of early earth and see if they could produce the initial prebiotic chemical reactions that are believed to have ultimately led to the dawn of life on earth.

What they did was pass water vapor through a mix of hydrogen, ammonia and methane gas. They then subjected that mix to periodic electrical discharges intended to simulate lightning. Then they looked at what came out the other side and it was, to say the least, interesting.

They found lots of organic compounds coming out of the mix. Most importantly, they initially found a number of the amino acids that are used by life. In 2007, however, the original sealed samples from the experiment were reexamined and as it turns out all 20 amino acids were present that are used by life on earth.

Since then, numerous revisions have been made to the model of what our planet's early atmosphere was like. As a result, a number of subsequent experiments have been done based on the Miller-Urey work ranging from changing the energy source to a volcano rather than lightning, adding in new chemical mixes that more accurately resemble what the early atmosphere is thought to have been like and so on. The results of many of these experiments has been the creation of even more types of organic molecules than Miller and Urey's experiment produced.

These experiments make it seem likely that at least the basic the chemistry for life first arose on some volcanic island on Earth billions of years ago. For Jupiter, this would be a more difficult process though it does have extremely powerful lightning and no shortage of heat. The problem is in its atmosphere, which is extremely violent. Gases circulate on that world by rising in certain areas and falling in others and any kind of life, microbial included, would have to deal with impossibly high temperatures and pressures when circulating deep below.

As Sagan noted in a segment on this topic in his television series Cosmos, such organisms would have to reproduce very rapidly. And while the prospect of life living in the atmosphere of Jupiter is somewhat of a stretch due to that roiling atmosphere, there may be gas giants and even brown dwarves in the universe calm enough to harbor at least some form of microbial life in their upper atmosphere, or possibly even more.

In a paper by Jack Yates and his colleagues at the University of Edinburgh from late 2016, link in the description below, they detail a hypothetical way for brown dwarves to harbor some form of life. They note that the upper atmospheres of some brown dwarves might harbor clement conditions with pressures and temperatures similar to earth. Relying on updrafts, life might exist in this zone within the brown dwarves.

This opens up vast new territory in the search for life in the universe. In 2013, a brown dwarf known as WISE 0855-0714 was discovered and seemingly has water-based clouds floating in its upper atmosphere. Using Sagan and Salpeter's research, they applied that thinking to the brown dwarf and concluded that yes, life might exist there.

The James Webb Space Telescope is slated to take an in-depth look at close brown dwarves, such as WISE 0855-0714 which is only 7 light years away. And while it's hard to envision native life having a way to evolve in the first place in a place like Jupiter or a brown dwarf, it's been suggested that dust floating in the atmosphere might do the trick for a solid place to do it or even microbial life being delivered by an asteroid through panspermia.

One can imagine that this kind of inhabited gas planet might be quite rare, but it does seem to at least be hypothetically possible and that in the future, when we do detect evidence of life, perhaps it might come from the spectra of a brown dwarf's atmosphere. But I'm left with one lingering, highly speculative thought after making this video. If Jupiter, then why not Saturn?

Thanks for listening! I am futurist and science fiction author John Michael Godier currently probably sounding a bit scratchy because it's spring and my allergies are working overtime 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: Life on Io?

One of great unknowns of our solar system is whether it hosts other life, particularly microbial. I say the words other life carefully because there are two types of potential life in our solar system for us to consider. The first of these is life that evolved independently of earth life without any influence from here. This would be truly alien life and would give us an indicator that microbial life in the universe at large is probably common.

The other potential for life in the solar system is life transported from earth via panspermia getting deposited somewhere else and gaining a foothold. Our planet is teeming with microbial life, some of it extreme and possibly able to survive the rigors of space. It's entirely possible that we, the human race, will not claim the title of being the first life from earth to colonize other worlds.

This has led me to research just where either of those forms of off-earth life might exist in our solar system. There are obvious candidates such as Mars or Europa, but there were other candidates that surprised me when I went searching for the science on the subject. This video is the first in a series on this channel exploring those places, and this candidate is one that if it does harbor life, it's probably going to be centuries before we know about it.

That's because it would be exceedingly hard to verify its existence. It's Jupiter's moon Io and the reason for why it's going to be a while is that there is just no compelling reason to try to land on this moon. Studies from spacecraft passing by from afar are feasible, but expensive and with life there only just being within the realm of possibility it seems that Io will not be a priority for exobiological study for some time.

First there's just not much on the surface, it's basically just a big ball of mostly sulfur compounds. And a lander might well melt as it's the most volcanically active body in the solar system kept so by intense gravitational flexing it as it orbits. But volcanism is a dual-edged sword. While it can easily kill life, it can also provide an energy source for its genesis and indeed some models for how life arose on earth depend on the presence of volcanoes.

A possible way for life to survive on Io was presented by Dr. Dirk Schulze-Makuch in a 2010 paper in the Journal of Cosmology, link in the description below. The key to the possibility of microbial life on Io is linked to its history. Io is old, having formed about 4.5 billion years ago and today it has the least water out of any object in the solar system.

But that may not have always been so.

Objects in the outer solar system are typically rich in water ice anyway, and the models suggest that Io formed in an area where water ice was particularly plentiful in the Jupiter system. Given geothermal heating, some of that water might have been liquid opening up the possibility for the chemistry of life to get going, at least for a while, this would have had to happen within the first ten million years of that moon's existence. And, as we learn more about the early conditions present in the Jupiter system, it may be the case that it was  always impossible for life to arise on Io. But, at least right now, there is a chance.

Now, life on Io's surface is improbable and not just because of the volcanic activity. Jupiter blasts its surface with very high levels of radiation, and that likely precludes any possibility of panspermia or at least makes the chances low unless it happened very early on and native life could not arise there now. But beneath the surface of Io the conditions might be just  right for microbes originating from Io's early history to hold out.

Jupiter's radiation long ago deprived Io of its surface water, but below the surface there may be carbon dioxide and water in liquid form. And Io could well have several other potential liquid solvents for life including hydrogen sulfide, sulfur dioxide and even sulfuric acid.

Another important factor to consider would be the presence of lava tubes. Lava tubes are rich abodes of life here on earth and may also be so on Io. They provide protection from radiation and can be moist environments and also temperatures within the tubes could be both constant and warm.

But that's not the only way. The paper advances another model where the microbes might exist as dormant spores underground for very long periods only to be activated when lava is flowing on the surface above warming any fluids below to liquid temperatures and allowing a blossoming of life for a time before it once again goes dormant.

So while life on Io is a long shot, and there are far better candidates in our solar system that we must look at first, Io may one day prove to be more interesting than we might have imagined.

Thanks for listening! I am futurist and science fiction author John Michael Godier currently with a new book in the works, it's called Supermind and a 5000 word excerpt is up at Amazon Kindle Scout, link in the description below, check it out and if you like it give it a nomination! 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: 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. 

Transcript: Ten Ways We May Have Already Detected Alien Life

In celebration of both this channel's one year anniversary and reaching three thousand subscribers, this is a full length documentary made in thanks to the fans of this channel for your support. I am having more fun creating my videos than a person should be allowed to have and the channel has become something that I really love and get excited about.

I never expected it would grow like this when I made my first video nearly one year ago, and it's all thanks to you folks for making it possible. Do look forward to many more years of videos which I will continue to make whenever I come across something cool and unusual in the world of science. So here are ten ways we may have already detected alien life in the universe.

Since the advent of space science, the human race have asked ourselves "are we alone?". In the past, answering this question seemed more straightforward than it is today with Percival Lowell's canals on Mars and pulsars being the signals from little green men. But none of that panned out and the fact is, we still don't know the answer to the biggest question in the universe. But we do know that life itself, at least microbial, seems fairly straightforward, resilient and easily arisen and may have done so on multiple bodies in our solar system alone. It seems likely that we are on the cusp of answering the question, at least far as simple life is concerned.

But what of other civilizations? This too seems to be increasingly moving into the territory of getting answered. If NASA researchers are to be believed, it could happen at any time and probably will within the next 20 years. But, in this search, we must be careful and cautious to prove that whatever we find does indeed indicate the existence of extraterrestrial life. That has not been easy so far.

It's worth noting that in the search for extraterrestrial life there have been many false starts, so it pays to take this entire list with a grain of salt. Two examples of this are HD 164595, a sun-like star with a known planet that appeared to be the origin of a radio signal and it became a major SETI target at the time. But the signal didn't repeat which is SETI's chief criteria, and it turns out, that the signal was within a military communications band. In other words, the origin was very likely a human-launched spy satellite whispering secrets from orbit.

Another example would be the near-earth asteroid 1991 VG. It's a highly unusual asteroid that has a really odd orbit that's a bit hard to explain. It's very similar to Earth's orbit, and that means earth should have long ago flung it out into space or smacked into it. It also has really strange, almost artificial looking reflectivity that makes it change brightness as it rotates to the point that one theory for its origin was that it was a spent rocket stage that someone had forgotten about.

But one other possibility that was floated at the time was that it was an object of alien origin known as a Bracewell or Von Neumann probe, more on those later. But over the years further research has revealed that it's just a strange rock and the alien origin possibility for it is now dead.

This list starts with the least likely candidates and ends with the most likely to have been something of alien origin. I included all life in the criteria, because even a single microbe answers the question. That is not to say that any of the cases will yield the answer to the 'are we alone?' question since some of the options are unlikely to repeat and thus probably won't be available for further study and will remain mysteries forever.

There are also some notable omissions for possible life, for example Europa where we currently have no indication that there could be life there, but the conditions are such that it would be unsurprising if such evidence were found in the near future. Those omissions are for a future dedicated list.

10. Tesla's Signals

This case suffers from being obscured by the mists of time and also a mistaken viewpoint of the period that Mars was almost certainly inhabited by an alien civilization. It clearly is not, the only alien civilization with a presence there is us. There is also a ton of misinformation out there on the internet regarding the originator of this possibility, and many, many urban legends have been spawned from material surrounding Nikola Tesla.

But the underlying claim does technically remain unexplained, though as I understand it and this comes from very old information I heard long ago, it would be extremely difficult to verify today because the frequencies at which it was supposedly visible are so saturated by earth interference that you'd have to put a receiver on the far side of the moon to block everything and check them out.

Nikola Tesla on several occasions claimed that he had received unambiguous alien radio signals from space. But he never gave much in the way of details that we could investigate today. He typically associated them with Mars, which at the time was subject to claims from several mistaken observers to have canals on it. It does not, and as far as radio goes Mars is about as uninteresting of an object as you can get.

Now, I don't doubt that Tesla did in fact receive strange radio signals during his experiments, but those were the very earliest days of radio astronomy done in a time when we had no idea what could emit radio waves. It turned out many things do, including objects in our own Solar System. You can literally grab an old short wave radio and make a loop antenna and listen to Jupiter make repeating ocean-like whooshing sounds that if you didn't know were natural, could be mistaken for something else.

As a result, I think this is a case of smoke without a fire. But since it technically remains unexplained, I put it on the list. Who knows what Mr. Tesla heard.

9. Long Delayed Echoes and Von Neumann Probes

This gets into unexplained radio phenomena that are almost certainly natural in origin. But since we haven't pinned down exactly what causes them, there remains a rather spooky possible alien origin though it is so far beyond unlikely and so highly speculative that I'm barely comfortable including it. But, since it's technically possible, on the list it goes.

In radio there is something called a Long Delayed Echo, or LDE. These occur when a broadcaster sends out a signal and then receives it back after a long period of time has elapsed, often tens of seconds. Now, there are lots of possible scientific explanations for these that included signals getting trapped into a loop going around the earth when the conditions are just right in the upper atmosphere, and signals can bounce off objects in space and return. While we don't yet know for sure, the explanation is most likely natural.

But, the universe is extremely old. Easily old enough for an advanced species in the galaxy to have developed. One possible way for such a species to explore the galaxy is to use self-replicating Von Neumann probes. These are probes that can make copies of themselves like viruses and spread out into the galaxy to explore it. The most famous example of this in science fiction would be Arthur C. Clarke's monoliths from 2001 - A Space odyssey.

With probes of this type, you could theoretically put a probe around every star in the galaxy. That would not take long, it could be done in as little as half a million years, but if your civilization is millions of years old then that's not really a big deal. And the expenditure of resources to do it would be very low, you'd only need to build a few initial probes and send them out to self-replicate. It's actually a scary doable way to explore a galaxy for a sufficiently advanced species, so much so that we're not that far from being able to start this process ourselves.

In fact, this method is seemingly so easy that one of the major arguments against it is that if Von Neumann probes exist, they should literally be everywhere and should have consumed most of the galaxy by now. So much so that any civilization that comes across one might see it as an existential threat and destroy it.

There are arguments for, against and neutral as to the existence of Von Neumann probes and their implications on the Fermi paradox. But it does open up the possibility of such a probe being stationed in our solar system awaiting the proper time to initiate contact and cultural exchange with us. One way such a probe might announce its existence is to repeat radio signals back to the civilization emitting them, sort of like the aliens from Carl Sagan's Contact sending back images of Hitler opening the 1936 Olympics as a sort of initial way to say hello.

Could that be the origin of at least some of the LDE's? It's highly unlikely, but possible. So on the list it goes.

8. Gamma Ray Bursts and Alcubierre Drives

This possibility makes use of a very contentious, hotly debated highly theoretical advanced technology called an Alcubierre warp drive. In a nut shell, the idea is that while matter sitting in normal space cannot travel faster than the speed of light, space itself is not subject to that rule.

So if you can split off and accelerate a piece of space, you can theoretically make it go as fast as you want. If you have a space craft generating a field of sorts to split that piece of space off and send it traveling, it would carry the spacecraft sitting within it along and voila, faster than light travel becomes possible and still remains consistent with relativity because the spacecraft isn't actually moving, the space it's sitting in is.

I will go on record and say that I do not think Alcubierre drives are possible. The subject is fraught with all manner of arguments against it being possible in practice, not the least of which would be truly titanic energy consumption to make it work. But it does have its advocates and the basic core concepts involved are fully scientific, so I include it on the list.

One effect of an Alcubierre drive is thought to be the generation of huge amounts of gamma rays. These should be detectable at long distances. And, we do, in fact, see all manner of strange gamma ray bursts in the universe that are not well understood. One possibility, be it a diminishingly tiny one, is that these bursts are being produced when aliens fire up their warp drives.

7. The Borra/Trottier Signals

In 2012, Ermanno Borra released a paper that suggested that you could detect within the spectra of stars the presence of pulsed laser emissions consistent with the activity of alien races. Along with E. Trottier, Borra then searched through the Sloan Sky Survey for the presence of these signatures.

At the end of last year, Borra and Trottier released a paper that reported that they had indeed identified these kinds of signals in the sky survery. But it wasn't just one or two stars emitting them, it was 234 different stars in the Milky Way. And, the stars that were emitting them were overwhelmingly sun-like, meaning that they had sufficient age and stability for them to have developed advanced alien civilizations.

But stars are strange things and emit all sorts of signals, so natural explanations are always favored. But, to date, no follow up papers have been published regarding this story so it's very much in flux still. But, at the time, scientists were careful to caution that on a scale of one in ten, with ten being the least likely, these signals were a ten. Only time and more study will tell.

6. Fast Radio Bursts

Fast Radio Bursts are a fairly recently discovered phenomenon. While it's overwhelmingly likely that these are of natural origin, one theory suggests that they may not be and are consistent with an alien civilization using a beam to push solar sails and the FRB's are the result of leakage from those beams.

What's noteworthy here is that FRB's do not seem to be consistent with something large, such as a star or galactic core. This is not yet settled, but it seems that they would be more consistent with something originating from a much smaller object, such as a planet.

If so, that would help bolster the solar sail theory.

But where it gets strange is that the solar sail theory makes note of an odd coincidence involving FRB's. If you take the theory from the position of energy and extrapolate what you would need to power the FRB beam, it comes out that you would need a planet about twice the size of earth to have enough room to collect solar energy to create the beam.

On the other hand, if you take the theory from the position of engineering and likewise extrapolate what you'd need to actually build the beam emitter, it ends up that the characteristics of FRB's would be consistent with a water-cooled structure that also happens to be the size of a planet about twice the size of earth.

I stress that FRBs are probably natural in origin, but it's also hard not to scratch your head when coincidences like that start popping up.

5. KIC 8462852

With this case, we enter a new level of possibility because it's the first case where the natural explanations so far advanced have all fallen short and the alien origin theory has still not been discounted.

KIC 8462852 or Boyajian's star is an enigma wrapped within an enigma. The Kepler spacecraft observed the star long term in 2011 and found that within the light curve of that star there were strange dips present as something passed by and blocked the star's light. This in itself would not be unusual, lots of young stars have disc of debris where planets are forming around them that produce light curves just like the one at Boyajian's star.

But the star's motion strongly suggests that this star is not young and should no longer have such a debris disc. That led to the possibility that two planets had crashed into each other in the system creating a new disc. Sounds fair enough. But there are two problems here. The odds that we would just happen to be looking when a very short term event like that happened are, well, astronomical. The second problem, and this discounted that theory, is that such discs absorb light from their star and radiate it back out in the infrared. No infrared radiation was detected at the star consistent with this. Whatever it is, if it's any kind of material, it has to be cold.

But, comets are very cold objects. So the next theory to come up was that a red dwarf, which is there, is passing by Boyajian's star and disrupted its oort cloud sending a hail of cold comets towards the star. Again, this would seem to be a perfectly reasonable explanation, you have the red dwarf as the culprit, we know from our own sun that Oort clouds exist and comets do get disturbed from them and head into the inner parts of solar systems.

But, then this theory fell short when sky surveys taken over the last century showed that the star doesn't just dim short term in dips, but has been dimming overall for a century. This would mean that you'd need a lot of comets in increasing numbers to account for this. The number needed is hard to swallow, on the order of 648,000 comets all orchestrated to pass in front of the star. That renders this explanation possible, but implausible, so other natural explanations are better candidates.

The problem is, every other theory involving a natural origin has some kind of Achilles heel that makes not fit very well. One theory is that the star is dimming and calming down after having recently ate a planet, but once again the chances of catching that just as it was happening are astronomical. It could also be some sort of material passing in the foreground, but we've never seen that sort of thing before and comes with its own set of problems.

So it boils down to this. Whatever we're seeing at Boyajian's star is a really rare phenomenon. If it's natural, whatever it turns out to be will be extremely interesting to science. However, if you have to resort to rare and unusual phenomena to explain something, there's one more possibility that might be consistent with what was being observed to occur at this star.

That would be gigantic alien megastructures. It is the least likely possibility, and has problems of its own. Where is the heat going that it too would radiate? Why is the rate at which it is blocking out starlight increasing? Is it under construction? But if so, how is it being constructed so fast?

The fact is, this mystery remains just as much of a mystery today than when the phenomenon first caught the public's attention. And the alien megastructure possibility still has not been discounted. So while it's very likely a rare natural occurrence causing this, the sticking power of the alien origin theory certainly raises eyebrows.

4. Life in the Clouds of Venus

If someone would have uttered that Venus might harbor microbial life just a decade ago, they'd have been called crazy. Venus seems, at first glance, to be a place unable to host life of any sort due being about as hostile of an environment as you can get on a planet. But in recent years, that's changed and there does indeed appear to theoretically be a way for life to exist in Venus' atmosphere.

The first indicator is Venus's history. Just after the late heavy bombardment about 4 billion years ago, Venus was not as it is today. Presumably, it would have been subject to the same amount of bombardment by comets that Earth and Mars were which would have delivered to it plenty of water. Venus would have been warm enough for that water to exist as a liquid. And while we aren't certain how long it might have had oceans, the estimates very wildly some going so far as to say 2 billion years.

The point is, there might have been plenty of time for microbial life to arise there. In fact, at that time in Earth's history single celled organisms were everywhere and actively oxygenating the atmosphere setting the stage for more than simple life.

But, if microbes did arise on Venus and water did persist for a long period of time, there might also have been enough time for them to adapt while Venus transformed itself into hell planet and become based in Venus's atmosphere in an area where the temperatures are earth-like and comfortable.

Coincidentally, in that same comfortable zone, there is some kind of material absorbing UV radiation. While there are some chemical possibilities to explain this, another possibility would be microbial life using the UV radiation as an energy source.

And, researchers have noted that the presence of sulfuric acid in Venus's atmosphere is not a showstopper for life. There is a way for life to coat itself with polymers known as S8 molecules to withstand the corrosive effects of the acid. As it turns out, S8 molecules have been detected in Venus's atmosphere.

So, it would seem, Venus may have just as good of a chance of having microbes as Mars does. It's certainly worth checking out, which seems to be on Roscosmos' agenda as they plan their next foray to the goddess planet.

3. Martian Meteorites

In 1996 a group of scientists from NASA announced that they had found structures that looked specifically like traces of microbial life in a meteorite known as Allan Hills 84001. It was such a sensation that Bill Clinton went on television and gave a speech about it.

This meteorite bears characteristics that solidly point to Mars as the rock's place of origin. That part isn't debated, it's a rock that was blasted off of Mars in impact. And it's an interesting rock, it appears to have been exposed to water in its past, as would be expected on Mars, and seems to have once been part of a subsurface aquifer. Such places on earth are often just right for life.

The problem with the claim was that these fossils, if indeed that is what they are which is still hotly debated, are significantly smaller than their counterpart microbes on earth, below the generally accepted limit thought possible for microbial life.

That's more than a little odd and gets into a debate about the existence of nanobacteria here on earth and those have been labeled the cold fusion of microbiology. And the debate over whether these structures in this and subsequently other meteorites linked with Mars are indicators of past life has never been settled. But it does remain a possibility, especially in light of the next case.

2. The Viking Biological Experiments

In 1976 NASA landed the first two probes to successfully function on the surface of Mars. Called Viking 1 and 2, they both functioned for years as stationary laboratories on the red planet taking high resolution images and doing soil analyses.

They were both highly successful as missions and greatly increased our knowledge of Mars. But the results of one experiment remain uncertain to this day, for good reason. The experiment tested positive for active microbial life on the surface of Mars.

Part of the problem was that this experiment directly contradicted another. The Labeled Release experiment showed that something was metabolizing nutrients in Martian soil samples. But, the other experiment was intended to determine if there was organic material in the soil, and it indicated that there was not. Metabolism without organics is not what you would expect from life, at least anything similar to Earth's microbes.

Now the labeled release experiment seemed to be a pretty reliable indicator. It was thoroughly tested on earth and never produced a false positive. Compounding this was the fact that both landers had the same experiments and both came up with the same results, despite being 4000 miles apart. It gets even stranger when you account for the fact that when the experiments were altered and done again after the soil was heated, the metabolic activity slowed, just as it would here on earth.

So that led scientists to look to nonbiological possibilities for the metabolism. There are several chemical processes that can mimic metabolism. One of these is formate which can produce a false positive. But it seems likely that Mars wouldn't have a lot of that, and the experiment where it produced a false positive did not have a corresponding sterilized control.

Another possibility is perchlorate, which Mars has been shown to have. The trouble is, perchlorate action does not slow down as you turn the heat up so the Vikings should not have seen a slowdown in metabolism when heat was introduced.

In 2013, a study showed that cosmic rays can make perchlorate break down. This yields hypochlorite the action of which would break down under heat and produce the false positive. But, proponents of the positive result being real, including the original researchers on the Viking missions, point out that hypochlorite hasn't been tested after long term storage of the material, which when doing that on Mars led to a negative result as though any bacteria present in the soil died off when stored. That leaves us without any solid non-biological candidates from which to produce the observed result.

Fast forward again. In 2014 Mars Curiosity detected the presence of organic molecules on the surface Mars. Why didn't the Viking experiments also detect organics if they were present? It turns out that Viking's gas chromatograph-mass spectrometer that was used to look for organics might not have been able to detect them at all and was never designed to look for life in the first place, and that was even stated by the head experimenter at the time in charge of the instrument. The plot thickens.

It has also been shown that the instrument would have required at least a million microbes to detect an organic signature. If there were fewer than that, the instrument would not detect their organics. To complicate things further, perchlorate destroys organic molecules and if it were in the soil, and if it were present at the Viking sites, well there goes the evidence for organics.

The bottom line here is that if these experiments had been performed on earth, where we unequivocally know that there is microbial action, the detection of life in the experiment would have not been questioned. Since they were performed on Mars, the bar is higher and it's difficult to imagine microbial life withstanding the harsh radiation environment of the surface of Mars, but on the other hand we've seen microbes here that can apparently use radiation in their environment to their advantage.

While a majority of scientists have not accepted this result, a vocal minority point out that life is the most likely explanation for the positive result in the Labeled Release experiment in so far as we know.

I don't know what to think either way, but this does qualify as very possibly having been a detection of life on Mars. I won't attach my usual caveat of "highly unlikely" to this one for the simple fact that we're looking to send humans to Mars and if there is any chance of alien microbes living there we need to know about them beforehand. More experiments are needed to answer question this once and for all.

1. The Wow! Signal

Topping the list, perhaps unsurprisingly, is the infamous Wow! Signal. It is perhaps the most unfortunate case, however, in that since it never repeated we are unable to study the nature of it and confirm whether it was really of alien origin. But even though it was detected in 1977, to this day no satisfactory natural or technical explanation for it has panned out and it remains the best candidate we've ever received for an artificial alien signal.

Part of the reason that the signal is so famous is that it bore all of the expected hallmarks of a signal sent by an alien civilization. And contrary to certain claims, the signal did not contain any message. It was just a continuous burst of raw radio energy at the hydrogen line, which is considered the most likely frequency aliens would use to say hello -- one that we on earth intentionally do not broadcast on in deference to SETI.

Now the telescope that detected the signal was stationary and relied on the rotation of the earth to scan the skies. Because of that, it was expected that any signal originating from deep space would be visible to the telescope for just 72 seconds. And the intensity of such a signal would rise for the first 36 seconds and then subsequently fall. Interference from earth would not do this, and both characteristics were present with the Wow! signal.

And, the bandwidth of the Wow! Signal was very narrow, which may further support the notion that it was artificial. Unfortunately, we don't know much else and the discoverer of the Wow! Signal, Jerry Ehman warns that we should not draw vast conclusions from half-vast data, so the origin of the signal is still open for debate. One should always be skeptical of anything that doesn't have confirmation, but out of all the potential signals that the various SETI efforts have detected over the years this is the only one where one could reasonably say "That may well have been it".