Ask Ethan: Would Life On Earth Be Possible If We Were Anyplace Else In The Galaxy?
“[W]hat would happen if our solar system had formed a little farther up the arm of the galaxy? What would happen if we were at the tip of the arm? What if, theoretically, instead of the humongous black hole in the center of our galaxy, our solar system was there? Would there be major climate difference[s]? Would we be able to survive?”
We can all agree that what’s happened here on Earth is something that’s extremely special in the Universe. Our planet has developed and sustained life on it for over four billion years, and that life continues to thrive even at present. Our planet has been fortunate enough to have stable enough conditions and mass extinction events that have never eliminated 100% of the life that exists on our world. But how ‘special’ does that make Earth, that this is our story? Do we need a large Moon? A solar system like ours? A star like our Sun? And do we need to be located at our present location in the galaxy, or would many places be just as good?
It’s a tough question to answer with certainty given the paltry evidence we have, but we can certainly examine these questions in-depth. Let’s do exactly that for this edition of Ask Ethan!
New Podcast: Humanity’s 3 Hopes For Alien Life
There are three very different ways humanity is searching for alien life beyond Earth. We can directly search the various planets and moons in our Solar System for past or present biological signatures simply by sending decontaminated probes, and looking for the evidence in situ. We can indirectly look at distant worlds around other stars, searching for the characteristic changes to the atmosphere and surface that life would bring. And, most optimistically, we can search for intelligent signatures created, perhaps willfully, by a technologically advanced alien species. These are our three hopes for finding alien life, and we’re actively pursuing all three.
Here’s how the different searches work, along with some speculation about what we’re likely to find, and what motivates us to look!
Humanity’s 3 Hopes For Finding Alien Life
“Although it’s just conjecture at this point, scientists speculate that life in the Universe is probably common, with the ingredients and opportunities for it to arise appearing practically everywhere. Life that thrives and sustains itself on a world, to the point where it can change its atmospheric and/or surface properties, may need to get lucky, and is likely more uncommon. Evolving to become complex, differentiated, multicellular creatures is likely even rarer. And as far as becoming what we would consider an intelligent, technologically advanced civilization, it could be so exceedingly remarkable that in all the Universe, it might just be us. Yet despite how different these outcomes are, we’re actively searching for all three types of life in very different ways. When the first sign of alien life finally is discovered, which one shall emerge victorious?
No matter which method pays dividends first, it will be among the greatest day in the history of life on Earth.”
There are three very different ways humanity is searching for alien life beyond Earth. We can directly search the various planets and moons in our Solar System for past or present biological signatures simply by sending decontaminated probes, and looking for the evidence in situ. We can indirectly look at distant worlds around other stars, searching for the characteristic changes to the atmosphere and surface that life would bring. And, most optimistically, we can search for intelligent signatures created, perhaps willfully, by a technologically advanced alien species.
These are our three hopes for finding alien life, and we’re actively pursuing all three. Which one, if any, do you think has the best chance of paying off?
Ask Ethan: How Close Could Two Alien Civilizations Get To One Another?
“What’s [the] closest two, independent intelligent civilizations could be, ignoring interstellar travel and assuming they develop in different star systems and follow roughly what we know as ‘life’? Globular clusters can have a high density of stars, but does too high a density rule out habitability? An astrophysicist in a dense cluster would have a much different view of the universe and the search for exoplanets.”
Okay, so you have a planet that has the right ingredients for life, and everything has worked out according to your wildest dreams. We’ve developed life, it’s thrived for billions of years, and now we’ve reached the point where we’ve got an intelligent, technologically advanced civilization, just like we do here on Earth. Let’s imagine we’ve got multiples, now, throughout the Universe. What’s the closest two independent ones could possibly be? Should we look in the same solar system? In a globular cluster? In the galactic center? In a spiral arm? In an open star cluster? Or should we just wait for another one to pass close by in interstellar space?
The science is open to all of these possibilities, but some of them are strongly disfavored based on the evidence we have. Come find out how close two alien civilizations could get to one another on this edition of Ask Ethan!
Despite Roasting Flares From Its Sun, Proxima b Might Still Have Life
“It’s true that stars that are very different from our Sun have restrictions on what conditions their planets can have and still be habitable. For red dwarf stars like Proxima Centauri, their worlds have conditions that make it unlikely for life to have taken the exact same evolutionary pathway that life on Earth took. But that doesn’t spell doom for life; it merely indicates that alternative pathways are required to arrive at similar outcomes. Frequent flares and excessive blasts of ultraviolet radiation may spell doom if Earth-based life were subject to those conditions, but organisms that have adapted to their environments could survive these outbursts routinely. A few solar hiccups a year should pose no problem for life forms that developed under those exact. harsh conditions. On every world, after all, it should be the organisms most robust against the adversarial conditions they face that will survive.”
The nearest star to us, Proxima Centauri, was discovered to have an Earth-sized planet in its habitable zone just two years ago. In that time, scientists have observed catastrophic flares comfing from the red dwarf star, fearing for the survival of any life on the planets orbiting it. Many now claim that planets orbiting red dwarfs are completely inhospitable to life, since the combination of tidal locking, ultraviolet-rich flares, ozone depletion, and a lack of higher-energy light in general would make photosynthesis and life-as-we-know-it an impossibility. How narrow-minded of us to go down that road! In reality, the energy source is there, the conditions are right for liquid water, the atmosphere as a whole will stick around, and there are many, many adaptations that could lead to life not only surviving, but thriving on a world like Proxima b.
It’s easy to look at a world that’s different from ours and declare how life like ours wouldn’t do well, but the key is to figure out what kind of life would do well there. That’s where the greatest chances for success are. That’s where we need to look.
Ask Ethan: How Fast Could Life Have Arisen In The Universe?
“How soon after the Big Bang would there have been enough heavy elements to form planets and possibly life?”
Making anything in this Universe takes time. After the Big Bang, there are a whole slew the Universe needed to take before rocky planets and life were possible. This includes the formation of atomic nuclei, neutral atoms, dense enough gas clouds to make stars, multiple generations of stars living-and-dying, and only then will the Universe be filled with the right ingredients to create rocky worlds and, potentially, life. But Earth didn’t come into existence until more than 9 billion years after the Big Bang, and these ingredients were around long before that. The heavy elements from the first supernovae could have made rocky, Earth-like planets very early on, but interestingly enough, it takes longer to form enough carbon to make life a reasonable possibility.
Let’s run through the Universe and find when life could have first evolved. The answer might be sooner than you think!
The Drake Equation Is Broken; Here’s How To Fix It
“Knowing how many worlds there are out there in the Milky Way with life on them, and finding even one, would have tremendous implications for our existence, and for understanding our place in the Universe. Taking even the next step, and learning that there were complex, differentiated, large organisms on a world, like we have with the fungal, animal, and plant kingdoms on Earth, would revolutionize what’s possible. And finally, the chance we’d have to have communication, visitation, and a knowledge exchange with a scientifically or technologically advanced alien species would forever alter the course of humanity. It’s all possible, but there’s so much more we need to know if we ever want to find out. We must take these steps; the rewards are too great if there’s even a chance of learning these answers.”
Put forth in 1961, the Drake equation was a brilliant step towards estimating the number of intelligent, technologically-advanced civilizations out there. But it was full of flaws: huge unknowns, assumed incorrect priors like the Steady-State model of the Universe, and thought only of its application to radio contact between worlds. Here in 2018, we’ve surveyed huge sections of the Milky Way, understand stars and extra-solar planets as never before, and have only a few major unknowns about life in the Universe left. All told, there are likely some 100 billion planets that could develop life on them, and only three big uncertain steps remain: the development of life from non-life, the evolution of life into complex, differentiated organisms, and the development into a technologically and scientifically advanced civilization.
Based on what we know and what we hope to find, we can do better than Drake ever did. Here’s where we are, and what’s left to learn.
Are Human Beings The Only Technologically Advanced Civilization In The Universe?
“There may never have been another intelligent, technologically advanced alien species in the entire history of the Universe. When you take into account that there may be 400 billion stars in the Milky Way, up to three potentially habitable worlds in many of these star systems, and some two trillion galaxies in the entire Universe, it seems like intelligent life is an inevitability. But our intuition can often lead us astray; what we feel is no substitute for science. The magnitude of the unknowns that abiogenesis, evolution, long-term habitability and other factors bring into the equation throws many of our assumptions about life into doubt. It’s true that there are an astronomical number of possibilities for intelligent, technologically advanced lifeforms, but the huge uncertainties make it a very real possibility that humans are the only spacefaring aliens our Universe has ever known.”
Given the huge number of stars, planets, and chances at life that the galaxy and the Universe has given us, it seems paradoxical that we haven’t yet encountered any form of alien intelligence or even life. The discoveries make in the field of exoplanet studies, particularly by the Kepler mission, make this an even bigger problem than we anticipated: more than 10^22 planets with Earth-like conditions are expected to exist in our Universe. But having so many chances, even with an astronomically large number like that, doesn’t necessarily mean we aren’t alone. The origin of life, the sustainability and development of complex, intelligent life, and the odds of technological success and ambition of a species that makes it are complete unknowns. We might enjoy thinking about these questions and exploring the Universe to hunt for answers, but the fact is that we don’t know.
Until we find out, it’s worth looking at all that’s possible, but we have to remain grounded. The truth may be out there, but we don’t have the solution yet.
Ask Ethan: Which Fundamental Science Question Is The Most Important?
If you could have a complete answer to one of these 5 questions what would it be?
1.) Did cosmic inflation happen or was there another process?
2.) Is earth the only place in the cosmos with life?
3.) How [can we] merge general relativity and quantum mechanics?
4.) What is dark energy and dark matter?
5.) How did life begin on Earth?
There are a very large number of unsolved mysteries in the Universe, many of which would revolutionize our understanding of what it all is… and what it all means. If you could know the answer to only one of these questions, but know it immediately and fully, which one would you pick? Would you want to know more about the origin of the Universe, pushing things back before the Big Bang? Would you want to know about life elsewhere in the Universe, far beyond Earth? Would you choose quantum gravity, or how to merge our two great, incompatible theories of how everything works? Would you want to know what dark matter and dark energy truly are? Or would you go for the origin of life on Earth?
There’s no right answer, which is to say there are five great answers, but not every answer is equal. Come take a deep consideration on this week’s Ask Ethan!
Afraid Of Aliens? The Science Doesn’t Back You Up
“The possible benefits to humanity of making contact are immeasurable. It would be like receiving a great galactic teacher, advanced thousands of years beyond our own scientific and technological capabilities. It would be the ultimate cultural exchange ever experienced on Earth. But the fears we have, that consume us, that lead to us eschewing the greatest cosmic achievement humanity’s ever dreamed of? They’re simply not based in science, logic, or reason. Thankfully, our fears don’t have to control our destinies. We can choose to use our minds instead.”
One of the questions that’s fascinated humanity since we first began looking up at the night sky is whether or not we’re alone in the Universe. Although we now know of other stars, other planets, and potentially inhabited worlds, we have yet to make contact with another intelligent species. Despite our curiosity, a great many people live in fear that if we did begin communicating with extraterrestrials, it would serve only to announce our presence to a potentially hostile (and more advanced) civilization. No one wants humanity wiped out, of course, but no one wants to bury our heads in the sand and to cease the search for one of the ultimate truths about our Universe. If you take a detailed, logical look at the problem, three possibilities for aliens emerge: they’re uninterested in us, they’re interested and benign, or they’re interested and malevolent. But even if they’re malevolent, they likely pose no danger to us, which you only learn if you put your fears aside and view the situation rationally.
There’s so much to potentially gain and so little to use, yet some of our greatest minds succumb to fear on this topic. Come take a look for yourself and see what you think!