4 Reasons why We're Probably Surrounded By Alien Civilizations

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00:00Human beings on Earth live about 25,000 light-years away from our galactic center.

00:06Our planet speeds around the Sun at about 66,000 miles per hour.

00:11We have our own unique place in space that seemingly, by some miracle, has allowed life

00:17to thrive.

00:18Except, what if it isn't actually that miraculous at all?

00:23What if really there are many reasons why we should be, even are, surrounded by other

00:29alien life in the cosmos?

00:33Let's get straight to it with reason number one, the commonality of life in the universe.

00:40When looking at instances of life, we of course have only one sample to draw upon, life on

00:45Earth.

00:46And there are plenty of studies and theories, including the Rare Earth Hypothesis, to suggest

00:50that maybe that's all there is.

00:52But equally, and in more recent times, we've seen more and more papers published arguing

00:56that life actually could be all around.

00:59One such paper was published in May 2020 by the Columbia University astronomer David Kipping,

01:05with a key takeaway being that it's potentially nine times more likely that life is common

01:09in the universe than rare.

01:11The study models the likelihood of abiogenesis, of the emergence of life, on other planets

01:16as per what we know to have happened on Earth, and concludes that there's good reason to

01:20believe that it would happen again, on another Earth-like world.

01:24For Kipping and his team, however, the likelihood of intelligent life isn't as high, with

01:28close to a 50-50 chance.

01:31But still, the suggestion is that if there are any alien species out there, then some

01:35of them will have developed into an advanced civilization.

01:38So, what are the chances that they're close by?

01:41Reason number two as to why we could be surrounded is the growing list of potentially Earth-like

01:45exoplanets.

01:47Exoplanets are planets outside of the solar system, and charting them is actually a relatively

01:52new prospect for astronomers, with the first official detection of an exoplanet coming

01:56as late as 1992… but, as of March 2021, there are now more than 4,400 confirmed exoplanets

02:04in the sky.

02:05Meanwhile, the topmost predictions for how many there could be in the Milky Way claim

02:09that there are multiple billions of other worlds in just this galaxy.

02:13Of course, not all of those will be Earth-like… but, according to a June 2020 paper by a team

02:18at the University of British Columbia, we can estimate that one in five sun-like stars

02:23does have an Earth-like planet in its habitable zone… which amounts to around six billion

02:27celestial masses within the Milky Way that are something similar to our pale blue dot.

02:32If we then imagine that, first, life can exist somewhere other than Earth, and again reason

02:37that it's nine times as likely that it's common than not, we could estimate that something

02:42lives on at least 5.4 billion planets that aren't our own.

02:46Then, if the chances of intelligent life really did turn out to be roughly 50-50, we're

02:51talking more than two billion alien civilizations.

02:53What's important to realise, though, is that this is still just one conclusion we

02:58could reach.

02:59It still stands that, actually, we've only recorded less than 5,000 exoplanets in total…

03:05and that only a fraction of those could claim to be in a habitable zone, as we currently

03:09understand it.

03:10It also still stands that we haven't discovered even one alien lifeform so far, intelligent

03:15or not.

03:16But, a growing number of scientists and astronomers do argue that the galaxy really could be birthed,

03:21bursting with life nonetheless… it's just that we need to work out how to access

03:25it.

03:26On to reason number three as to why we're probably surrounded… time.

03:30We know that the Milky Way has been around for around 13.5 billion years, and we also

03:35know that it hasn't always been the exact same cosmic mass as it is today.

03:39It's shifted and developed over time, and indeed, the evolution of our galaxy to this

03:44precise point is one of many key reasons why we can exist right here, right now.

03:49In the search for alien life, we so often speak of habitable zones.

03:53We've already mentioned them in this very video… but we're usually contemplating

03:57them as a physical space, as a band around a star wherein a life-supporting planet could

04:02orbit.

04:03Alongside all of that, though, there are temporal habitable zones… moments in, and periods

04:08of time when conditions align to create the best chances to form life.

04:12And the interesting thing is that, according to one study, the Milky Way's optimum time

04:16for life was long ago, to the tune of 5.5 billion years back in cosmic history.

04:22A December 2020 paper by Caltech calculated that the probability of life in the Milky

04:27Way peaked around 8 billion years after it formed, and around 13,000 light-years from

04:32the galactic centre.

04:33Earth and the solar system are now almost double that, at around 25,000 light-years

04:38away from the heart of the Milky Way, and 5.5 billion years further down the timeline.

04:43We took a closer look at this study in another recent video on our channel, so check that

04:47out after this.

04:49But say there was a population boom at an earlier stage in our galaxy… then couldn't

04:53we now expect there to be various ancient civilizations dotted around us?

04:58And if they've potentially been evolving for billions of years longer than life on

05:01Earth has, then could they potentially be far, far more advanced than we are?

05:06Again, there's no way to know for sure until we encounter one… but the thought begins

05:10to make the whole of human history feel really quite small, alongside the potential for everything

05:15else.

05:16But, even though there has seemingly been time enough, there are potentially planets

05:20enough, and studies show that the likelihood is that alien life does exist somewhere…

05:25the disappointing reality remains that we still haven't discovered anything.

05:29A growing number of scientists believe that there must be extraterrestrial intelligence

05:33in the universe… and probably in our galaxy… but nobody has found it.

05:38So, reason number four why we're probably surrounded is because we're not yet advanced

05:42enough to know what's really going on.

05:45Across the many ecosystems of Earth, humans reign supreme.

05:48We've built towns and cities across most of the world map, and we've travelled to

05:52almost all Earthly locations… and yet, our successes outside of Earth's atmosphere

05:57are limited.

05:58There's no doubt that our space travel achievements thus far should be celebrated, but they still

06:03only amount to a small number of far slower-than-lightspeed machines.

06:07Only two of which, the Voyagers, have ever broken out into interstellar space.

06:12And a handful of human travellers making it onto the next closest thing to us, the moon.

06:17Our impact on the wider universe is, then, at this stage, very small.

06:21The Great Filter is an often-debated concept whenever talk of advanced civilizations comes

06:26up.

06:27It proposes that there's something, at some stage of civilization development, that puts

06:31a halt to it all.

06:32There's some kind of biological or technological hurdle that very few civilizations can pass.

06:38And that's why space appears to us to be so… silent.

06:41The next question is, has humankind already passed the Great Filter, or are we yet to

06:46encounter it?

06:47If that second scenario is true, then it could be that we're just not at the required level

06:51to engage with alien civilizations yet… and we might never be.

06:55Meanwhile, those select few alien groups who have passed the filter have steadily grown

07:00and grown all around us, despite us being naturally oblivious to them.

07:05Finally, filter or no filter, it could simply be that we haven't allowed ourselves enough

07:09of an opportunity yet, to encounter and understand any potential alien groups.

07:14In a joint-authored 2016 paper by Cornell University students Evan Salamonides and Yerban

07:19Terzian, it's argued that we could be waiting 1,500 years before any real progress is made

07:25toward first contact with aliens.

07:27The study, entitled A Probabilistic Analysis of the Fermi Paradox, reminds us that we've

07:32only truly been searching in earnest for aliens for about a century, and also predicts

07:37that less than 1% of the Milky Way has been reached in any way, by anything… which offers

07:42one explanation as to why we so far haven't crossed paths with aliens, but also opens

07:47up the possibility that there could be plenty of them out there.

07:50It's just so unlikely at this stage that we'll have clocked them, or they'll have

07:54clocked us.

07:55So, there we have it.

07:57It can be argued that it's statistically likely that aliens abound.

08:00It's becoming clearer and clearer that there are enough exoplanets in the Milky Way to

08:04host them all.

08:05According to one recent study, there's been comfortably enough time for them to have emerged

08:09in this galaxy… and the final explanation as to why we've not spotted them yet is

08:14because we're not advanced or clever enough ourselves.

08:17Or we're just too impatient.

08:19And those are four reasons why we're probably surrounded by alien civilizations.

08:24What do you think?

08:25Is there anything we missed?

08:26Let us know in the comments, check out these other clips from Unveiled, and make sure you

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