Where Are All the Aliens?
Speculations by Stefan Stenudd
And now, Stephen Hawking declares that there will be a ten year initiative to search for aliens by scanning the sky for intelligent radio signals, much like the old SETI project but with a USD 100 million investment by a Russian entrepreneur to improve things. Here is a BBC article about it: Venture to listen for aliens.
Are there others out there in space? We don't know, because we have no signs of it either because we can't read such signs or because nothing that may be out there is able to reach us with any kind of evidence of its existence.
The problem has these two aspects, provided there is intelligent life out there: Can we detect it, and can it reach us?
Probability SupportFirst of all, though, the question is if there are others out there. Probability calculations on the vast number of planets in the universe indicate that there must be lots of them with the conditions needed for life to emerge and evolve.
As we understand life and that's far from completely nothing suggests it could not happen elsewhere. Considering the quantity of planets out there, it is most likely to have happened numerous times. It probably keeps on happening.
How about intelligent life? Again, the odds are for it, because of the high number of planets likely to produce living creatures. Even if life is rare, the universe is big enough to have plenty of it outside earth. And even if it's much more rare for life to evolve into intelligent beings, it should have happened a lot of times in some cases so long ago, their civilizations have developed far beyond ours.
Universal DarwinAs for how life develops, Darwin's theory of evolution would apply to any other planet as readily as on ours. Strictly speaking, it applies to any system of continued change, whether it happens randomly or not.
The theory of evolution increases by time the chance of highly advanced life forms anywhere life has started. The more time passes, the more advanced creatures will emerge.
A word of caution, though: Survival of the fittest doesn't necessarily mean the most intelligent ones. We don't know that intelligence is a major asset for survival, at length. We have only had this big brain of ours for a fraction of the time other life forms on earth have survived fine without it. And it seems our minds play lethal tricks on us, sometimes surpassing the benefits we have achieved by them.
In other words our intelligence may be our doom, and not our blessing. So far, it's working well, allowing us to spread over most of the globe, increasing both our life expectancy and population impressively. But it comes at a high cost, and the future may show that we've walked right into a cul-de-sac of self-extinction.
Increased intelligence may be comparable to bodily size: it is beneficial up to a point. Most really big animals that have walked the earth are gone. That could be the rule for intelligence as well. More than enough might be detrimental.
What's Intelligent?As for intelligence, we tend to measure it with ourselves as the scale. We like to see ourselves as the peak of intelligence on earth, but that sure depends on how we define it.
We are not the only animals with big brains. Ours is not even the biggest or the most advanced by any standard of which we are aware. So, we have no reason to assume that our brains are the most intelligent ones.
There's not much that makes us unique. Many animals form complex societies, many use tools and know how to modify them to their advantage. Most of them have sophisticated ways of communicating with each other. Strictly speaking, except for walking on the moon, what have we done that is completely beyond every other animal's ability?
We have science, the ability to understand how the world works and use it to our advantage (sometimes also to our disadvantage). What has made us achieve this is the combination of our brains and our hands. Judging from what other animals succeed or fail to master, the hand may be even more important than the brain.
Without our hands, we would have to settle for having very fancy dreams.
Now, this combination in all its splendor is yet to be found in any other species, although there are millions of them on earth and they've all had plenty of time to evolve. Only one species, our own, is at all able to travel and communicate beyond our planet and we only developed that ability recently.
So, it took earth five billion years to produce one species able to communicate and travel beyond the planet.
One in millions of species. That's not much. And it took as much as about half the time our sun remains stable enough not to expand and consume our planet. Had the process taken twice as long, it would be too late.
We don't know how to calculate the probability of life to appear and evolve on other planets, but present estimates (the Drake equation and such) hint on it being much more likely than one in millions. But the give and take of it is tremendous.
According to Wikipedia the original 1961 estimate by Frank Drake and his colleagues was between 1,000 and 100,000,000 civilizations in our galaxy. Current estimates broaden the scope even more from just two up to 280,000,000 civilizations, again in the Milky Way only. The total number of galaxies in the universe is estimated to be between 100 billion and 200 billion. It could as many as 500 billion, but most of them are significantly smaller than ours.
So, although life is very likely to have emerged on countless planets in the universe and intelligent life on quite a lot of them, creatures able to explore space are much less likely to appear. Judging from earth statistics alone, that's another one in a million chance.
Evolution is not heading for space.
Very ScarceAlthough evolution is no guarantee for space exploration, it happened to us so it could happen elsewhere. Given the very high number of planets in our universe where life is possible, we are probably not the only ones reaching for the sky. But the others may be very scarce and extremely distant.
Do they want to reach us? If they are space explorers, they should be curious enough to search for creatures like us. Some may already have discovered us, even reached us in some way or other. If so, the problem is that we can't spot them.
SETIHow to discover aliens? If they are somewhat like us, the SETI search for intelligent radio signals from space would be one way provided they are close enough for radio signals to reach us (now that we search for them) before they change to other modes of communication that we can't read. And provided they ever used that method.
Any mode of communication below the speed of light would be very primitive and unlikely to traverse space. Methods of light speed communication used by those who want to explore space must work at interstellar distance, for the sake of their own use of them.
So the signals should reach us, which doesn't mean we can receive them today. But SETI thinking might get us there. It has not done so yet, although this search started, albeit modestly, already in 1960. SETI has detected no sign of intelligent communication out there.
Civilizations on other planets don't even have to aim for interstellar communication for us to pick up their signals. We have sent radio waves into space for over a hundred years, although mostly we just wanted to communicate on our own planet. That means we've announced our existence more than a hundred light-years out from our own modest location in the Milky Way.
Extraterrestrial civilizations would have done the same, once they developed that technology. That's what the SETI project hopes for. But we've only been scanning space for such signals during mere decades.
If radio wave communication is the lasting modus operandi of any technically advanced society, then some of them must have been around long enough for those signals to reach us by now. But if they switched to something else as they continued to advance their science, we might have missed them. Their radio waves passed us before we were able to discover them.
For example, if they shifted to some kind of laser beam communication, it would be unreadable outside of its intended target.
What we can hope to catch are signals from extraterrestrials who used radio waves in time periods fitting these few years we have listened for them. That may bring the number of possible hits down substantially.
In case there actually are civilizations communicating with radio signals that reach us now, we just don't interpret them as such. Is the SETI algorithm for deciding intelligent signals insufficient?
Maybe that type of communication is either rare in itself among advanced civilizations, or something they soon abandon for other methods. We should ponder what other ways there may be to spot technically advanced societies at interstellar distance.
The Time It TakesAlthough probability allows for plenty of beings out there able to contact us, it also says that they are not likely to be in the immediate vicinity of our solar system. Even the nearest star is four light-years away. That's four years, one way, at the speed of light.
Within a 20 light-years distance, there are only 59 star systems. Not many enough to cause a high probability of a civilization from this radius reaching us, one way or other.
Just sending radio signals in the hope of our response demands a lot of patience. They would have to wait for tens or even hundreds of years for a response. Would we have that patience?
Due to the relativity of time, manned interstellar travel approaching the speed of light if that's at all possible would not take too long for the crew to manage. But that would not apply for an unmanned vessel, being scanned from home by its maker. Those sending it out would just have to wait for very long.
So, interstellar reach makes more sense when manned than when not. The travelers themselves get something out of it, though the price is that when they return to their home, generations have passed.
Unmanned vessels, on the other hand, would be too much of a strain on anybody's patience to be pursued with any vigor.
The space traveler is not an unlikely creature to pay us a visit, even from a star system not in our immediate vicinity provided the mode of transportation allows for a speed not too far from that of light. Not only will the speed slow down time for the traveler, so that the voyage doesn't take ages. But also, since it demands beings with a life expectancy surpassing ours, they would not be as bothered by the time the trip takes.
Any creature anywhere can't perceive time without relating to the personal experience. The longer you live, the faster the years seem to go. That's simply because our minds mainly measure time according to how much of it we have had so far. It is also quite likely that life expectancy has an influence. The longer we expect to live, the more patience we have with things taking time.
Prolonging life is not that difficult, our science has already revealed to us. We can still only do it to a point, not that much above a hundred years, but it's not at all unlikely for conscious beings to exceed that barrier multifold. Even here on earth, there are creatures living substantially longer than we do not to mention plants.
The ideal space traveler, then, is someone living for very long and correspondingly patient. Not an unlikely creature at all. More likely than a bunch of civilizations sending unmanned probes and keeping their curiosity through all the years they have to wait.
Plausible Space TravelersHow likely are such space travelers to reach us? That depends on how close to light speed it is possible to travel. The faster the travelers can go, the wider a radius from their home they can explore within a time reasonable to them.
The spacecraft we have sent the farthest so far is Voyager 1, launched in 1977. It reached interstellar space (left the solar system) in 2012. Voyager 1 travels with a velocity of 61,000 km/hour, which isn't much compared to the light speed of 300,000 km/second. That means it would take the spacecraft something like 70,000 years to reach the nearest star. Don't hold your breath.
Also, at that modest speed, a passenger would not experience much less of a time.
For space travel starting to be meaningful, the speed should at least be something like 1/10 of light speed. That means Voyager 1 would have to travel more than 17,000 times faster than it does. So we're very far away from accomplishing it.
But that would make a trip to the nearest star take 40 years. A lot, but doable. The relative time on that vessel would be less, but not by more than around 1%. It's not a linear relation.
Significant change of time starts above 70% of light speed, where time is around 25% slower. At 95% the traveler's time will be 1/3 of an outside observer. At this phenomenal speed, the traveler will have reached our nearest star in a little more than a year (but at home, 4 years will have passed). That speed, though, is very much to hope for...
At the very speed of light, time has stopped. For light, there simply is no time, no matter how long it takes to reach some outskirt planet of the Milky Way. Travel at that speed would be instant anywhere, were it possible. As far as we know, it's not.
So, the important thing with speed (as long as it's not very near that of light) is not how much it shortens the time for the voyager, but how quickly the vessel reaches its destination. Therefore, visitors from other star systems are more likely the closer they are to us much more likely if they are within, say, 20 light-years, and very unlikely if they are much farther away than that. Most star systems sure are.
Beam Me OutTheoretically, it is possible to travel in light speed without upsetting the order of the universe. A kind of Star Trek beaming device would do the trick. If we can deconstruct ourselves completely into code that can be sent by radio signals to a destination, where we are reconstructed, we would relocate by light speed.
But we would have to know that the code creates complete replicas of us, with personality, awareness, memories and all.
If we can do that, then of course we can also create infinite copies of ourselves at the moment of copying. Once the copies are made, their following experiences will set them apart. If they are to update one another, again light speed is the limit to how fast that can be done. At interstellar distances, this can be very tedious indeed.
Travel by such code cloning would mainly create an identity crisis. Who is the real me?
Still, such a solution would not challenge science's knowledge of natural law one bit, nor its present understanding of what constitutes a human being. We would just have to rethink what individual life is.
A way of recreating ourselves completely might prove so spectacular that space travel is trivial, even pointless, in comparison. And light speed is still the limit, making most of space unreachable over foreseeable time.
Beyond the Speed of LightThe above suggests that those able to reach us are so far away that they would be unlikely to even bother, without a method of communication surpassing the speed of light.
If there is communication beyond the speed of light, can we receive and read the signals? Potentially, yes, if we make that breakthrough.
But we are far from there, not even (as far as I know) clear of the natural laws involved. What universal law would allow for communication beyond the speed of light, and what would be the nature of that communication?
Einstein's laws of relativity don't deny the possibility of a speed beyond that of light. They just state that nothing below that speed can accelerate beyond it, or the other way around.
So far, there has been no firm proof of faster-than-light objects. But theoretically, if there is something traveling at such speed, it might be used to transfer information. Some suggest that it would be information backwards in time, though, as in the idea of the tachyonic antitelephone but that is regarded as impossible by present physics.
Actual space travel beyond the speed of light would be utterly impossible, as we understand physics, but some kind of communication by making use of things constantly moving beyond the speed of light might not be completely out of the question. Tricky, though, to say the least.
Since it still can't be ruled out, there may be very advanced civilizations out there doing it. But we are unable to recognize such communication, not even knowing where to search for it. Aliens using it would do so without any risk of us finding out at least not until we get the hang of it.
Nearby WormholesFor space travel, something like a wormhole might do the trick, quickly or even instantly taking the traveler from one spot in space-time to another. It may be possible, but surviving the transition is quite another matter. Not to mention controlling where and when the destination will be.
Still, space travel through wormholes or similar space-time absurdities can't be completely ruled out. But we are yet to find a wormhole and to make use of it. That's not likely to happen any day soon.
If wormholes do exist and there is some way of traveling through them, there may be an alien civilization mastering it. Then they could come knocking on our door at any time. We would have trouble understanding how they got here, but other than that we would be perfectly able to perceive them and relate to them.
For interstellar contact in person, this seems to be the least unlikely solution that we are aware of, yet. But the wormhole to be used must be rather near the home planet of the traveler at one end, and earth at the other. If not, we are back to the problem of lengthy space travel. That's the catch with the wormhole solution.
In other words, wormholes have to be in abundance all over the place for space travel through them to be meaningful.
Should wormholes allow for time-travel as well, we may even be visited by future generations of our own species. But that's a matter of dispute among scientists. Going forward in time is no problem at all. That's what we all do, and it can be done at different speeds. But backwards, that's quite another thing.
Not That EasySumming the above up, meeting or even communicating with our interstellar neighbors is not that easy. The Fermi paradox claims that the probability for other intelligent life out there to be so abundant, it's a mystery we haven't heard from them yet. But the equation used seems to underestimate some obstacles:
It's more than likely that there is life on other planets, also intelligent life due to evolution. But evolution is all about survival, so the ability and ambition to explore space is not necessarily a result of it. On our planet, only our species out of millions has reached it and that only very recently, after half the expected lifetime of our planetary system has passed (before the sun grows to a red giant).
So, even if life is commonplace in the universe, other space exploring civilizations are very unlikely in our vicinity of the galaxy. They would be so rare that we must expect them to be very far away from us, even by astronomical standards.
The speed of light limit on any information makes efforts of interstellar communication extremely time-consuming. Even radio signals would take tens or hundreds or even thousands of years. Manned spaceships would take close to forever. What species advanced enough to calculate the time it takes would bother? With technical advancement comes impatience.
A popular idea is to traverse vast distances in the universe through wormholes, if that's at all possible and if they do at all exist. But they have to be commonplace, or it would still take space travelers far too long to reach them, and to reach the destination after exiting one of them.
So, even though there may be others like us out there, it would be foolish not to give up the idea of meeting or even communicating meaningfully. It would simply take far too long.
Science SpeculatesAs mentioned above, wormholes are not enough if they're not just about everywhere and lead everywhere we want to go. The problem remains even if we learn how to build them we need to do so at both places they link, before we can use them to travel between those places.
There are some other speculations, such as traveling by warping space-time in some fantastic way. That might get around the problem of the light speed limit. It's an interesting thought, expressed by Miguel Alcubierre sort of moving space instead of the space vessel.
If the universe allows for it, it might one day be doable. The question is what it does to the universe, though. Who knows at what space and time the traveler would end up?
Also, it may be very tricky for the vessel to stop a process taking place completely isolated from it. And a separate control from outside of the vessel is out of the question, since it would have to manage the same speed.
Using tachyons or other objects moving faster than light (if they exist), without needing to catch up with them, might solve the problem of interstellar communication. But hardly travel. Accelerating beyond the speed of light is a definite physical no-no.
A Different UniverseAlthough visits from space are plausible in several ways, the vast distances involved and the time they consume by any means of communication is the recurring obstacle. At least if our understanding of the universe is the correct one.
Is it, surely? Can we definitely exclude a universe where traveling way beyond the speed of light is possible in some strange, yet unknown way?
For the sake of speculation: What kind of unknown laws of nature not rejecting what we have observed with certainty about it would give the means of convenient interstellar travel?
Well, the universe we study has its laws and they bind us, simply because they are based on the definitions we use to study this universe. The laws by which we understand the universe must be kept, or we don't understand the universe at all.
The history of science has several examples of this paradox. We can only find what we search for, and we can only search for what we think is possible to find. So, we tend to find what we expected to find, and little else.
Until not many centuries ago, European dogma was geocentric, putting the earth fixed in the middle of the universe. The church was eager to keep this view, because it was supported by the Bible.
It made astronomical calculations rather complicated, especially due to the planets' retrograde movements but they managed with a theory that made sense to them. Ptolemy's geocentric model from the 2nd century did fine until Copernicus presented his heliocentric alternative in 1543.
While laughing at the ignorance of Ptolemy, we may be making a similar mistake, explaining the universe with a model that works for us but is still far from the truth. It is very difficult to shift the perspective from how we are used to see things, in order to try something completely different. But that's what is needed for any major scientific breakthrough.
So, we should always start any daring speculation by trying to step out of our own box. Only if we question our perception of reality can we reveal what might be behind the mirage. In other words, we need to understand ourselves to understand the world around us.
So, what kind of universe would allow convenient interstellar contact and travel? If we come up with a decent hypothesis and then search for that universe, we might find it. And aliens, too.
PSBack in 2012, I wrote another essay about finding aliens: We See the Aliens When They Cease to Be Alien.
July 21, 2015
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