The Fermi Paradox: Multiverse

The Fermi Paradox: Multiverse

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This episode is brought to you by Brilliant. Our Universe is enormous and ancient,   so we suspect it of being home to many alien  races, and yet it may be but the tip of the   iceberg. We may live in a Multiverse so vast as to  dwarf our Universe, home to uncountable species.   The Fermi Paradox is the big question of  why, in a Universe so vast and ancient,   we don’t see any other bigger and older  civilizations, and it arose from our realization   in the early 20th century of just how big and old  the Universe really is. At about that same time,   we began to contemplate how we might have parallel  realities and alternate Universes, leaving   even more potential to search for alien life. Our approach to the Search for Extraterrestrial   Intelligence, or SETI, never really discusses  Multiverse options, for the simple reason that   almost everyone assumes we can find our first  example of intelligent aliens in our own galaxy,   and need not consider the whole wide Universe, let  alone other Universes to find example number one.   And yet, there are several reasons this  assumption might be wrong, and that our first   encounter with aliens may involve alternate  realities. Even if it doesn’t, the topic of  

interacting with and meeting aliens through the  Multiverse is interesting in its own right.   We’ll begin by quickly reviewing what  a Multiverse is, or what it might be.   For more details, you may want to check out our  episodes Alternate Realities & Parallel Universes,   and Infinite Improbability Issues, for more  discussion of the science of how these work,   as well as the Quantum Cheeseburger. Speaking of  Cheeseburgers, our Fermi Paradox episodes tend   to be on the longer side so you might want  to grab a drink and snack before starting,   and if you enjoy our episodes, don’t forget  to like, share, and subscribe to the channel.   So, what is a Multiverse? There are actually a  ton of different ways you can have a Universe   beyond our own, but the one most commonly  discussed nowadays tends to be the Many   Worlds Interpretation of Quantum Mechanics. This  is the main alternative to the one presented   by the Schrodinger’s Cat thought experiment,  which is a popular example of the Copenhagen   Interpretation of Quantum Mechanics, and I do want  to emphasize that they are potentially alternative   explanations of the same idea: either one is  true, or the other is true, or neither is true,   not both. To clarify, Schrodigner’s Cat is the  example where a cat in a box has been poisoned  

by a poison delivery device triggered by the  decay of a particle, which is an example of a   quantum event acting at the macroscopic scale,  or the subatomic acting at the human level,   or in this case the cat level. The Copenhagen  interpretation says that the cat is both alive   and dead until we open the box, at which point the  cat is either one or the other when we observe it.   But until that observation is made, both alive  and dead are equally valid states for the cat.   The Many Worlds Interpretation argues that the  cat is alive in one reality and dead in another,   and that opening the box to check just tells  us which of those two Universes we’re in.   Of course, this should be true for every event,  so there’s a reality where the cat is alive,   one where its dead, one where it never went  into the box, one where it escaped the box   and attacked Schrodinger, and one where  it is alive in the box and a tree fell   down on the other side of the planet, and one  where it’s alive and the tree did not fall.   The idea that all of these potential realities  exist simultaneously leaves you with many worlds   for every event, with one world for every  possible state or every possible action. And  

this isn’t just true of cats: there’d be countless  Universes we could assemble from every state and   configuration of every available particle. This  number of Universes is so enormous that even just   writing out that number on a piece of paper  would take more sheets of paper than we have   ever produced for every book ever written. Even  if we were to limit every universe to a single   unique address, like a Universe phone number,  and store it on a digital medium so advanced you   only needed one atom per bit of data, it would  collapse under its own mass into a black hole.  

In other words, it’s a lot of Universes.  And mind you, that doesn’t even include the   far more numerous options we have when we start  contemplating different Universes. Ones identical   to our own but where the Big Bang releases a few  more atoms or a few less, or ten times as many,   or where the speed of light was 3 billion meters  per second, not 300 million, or 3, or 3.0001,   or protons weighed just one millionth more than  they do here, or a billionth, or a trillionth,   and each of these have their own Multiverse  that has an insanely huge number of possible   combinations each atom can be in. And none of this contemplates an Infinite  

Universe. All of these, each scenario we just  considered, would still amount to a finite number,   and so is still essentially meaningless  on an infinite scale. When considering the   Fermi Paradox, which is all about how strange it  seems that we’re alone in our giant and ancient   Universe, taking the Multiverse into account  exacerbates that issue to the point of absurdity.   In a Multiverse, every possible option which  can exist, must exist. So at some point you   might even have a Universe where intelligent  life is literally emerging from nothing,   what we call a Boltzmann Brain, with no need  for evolution or even a habitable planet, simply   because there is a finite chance of it happening. So what are the implications of all this? Well,   if the Many Worlds Interpretation of Quantum  Mechanics is right, then any alien that could   ever exist inside physical laws must exist  in our Universe’s Multiverse. In fact,  

because of the potential variation in those laws,  it might be that there are some possibilities we   can’t even imagine. It would mean they exist in  at least one of Earth’s various reflections too,   since there should always be some version of Earth  in which that organism could also have existed,   including ones where it had not evolved but  simply formed, like our Boltzmann Brain.   I mention that particular point because if  it’s possible to travel between Universes,   then our chance of encountering aliens needs to  consider that they need not travel very far in   space to meet us. Indeed, this is a big conundrum  a Multiverse raises for the Fermi Paradox.   If travel between these alternate realities is  possible, it would raise two very big concerns,   one of which would be aliens on  copies of your own world visiting,   with the other being that a given species  needs no motivation to colonize other planets.  

Let’s address that second point first. If you consider the implications of having access   to other universes, it soon becomes apparent that  you wouldn’t really need to colonize space at all.   While there are billions of galaxies out there,  with billions of star systems to settle, that   number of potential new homes is still miniscule  compared to all the effectively-identical Earths,   where the only difference is that humanity never  arose. Perhaps that first critter that we think  

of as the bridge between man and ape just didn’t  occur yet, or died when it did, or its early tribe   got eaten by predators a year before it would  have divided to form another tribe, and so on.   There would not be an infinite number of  suchs worlds, but they would certainly   outnumber the potentially habitable worlds  in our current Universe. Indeed they would   do so by a greater factor than the number of  atoms in this Universe outnumber its stars.   And that’s just the options where humanity could  safely wander into those copies so close to our   own we could hardly tell them apart, except  for their having never been home to humanity.  

Which is a pretty big exception, since there  should be a near endless number of worlds   identical to the here-and-now, including all  our buildings and crops, and warehouses full   of manufactured goods, except that all the people  on it died yesterday, or five minutes ago. Fully   colonized and terraformed worlds you could just  step through a portal and inhabit certainly seem   preferable to trying to terraform Mars, much less  spending decades travelling through the depths   of space to some other, more distant place. Now personally, I would think it a bit ghoulish   and lazy to take over a corpse-reality where  everyone had just died, rather than building   fresh on some virgin world where mankind has  never tread, even if it's just an Earth-clone   where mankind never arose, or where the dinosaurs  never died out. But I imagine that Corpse-Earths,   near-identical to our present but with all the  humans gone, would be a popular choice since   they’re immediately ready to go. Presumably they  would also be littered with novel bits of science,   technology, and art that haven’t  been produced by our civilization.   I would still be worried about why they were  uninhabited, though. It is true that there is  

always a random chance everyone just spontaneously  ceased to exist, but the probability of that is   stupidly low compared to some more mundane  cause of mass extinction, and thus virtually   every world you would find that had our cities  but not us is going to have an accompanying   reason for that absence, like a super-plague, an  alien invasion, or some neutron bombs going off.   Unless you have some way to pick or sort them  beyond looking at them, you will nearly always   have a clear and present cause for an extinction  event that might get the colonists we send there.   Incidentally, the notion for random things  appearing or disappearing in quantum mechanics is   somewhat similar to the concepts we’re discussing,  in that there is always a finite chance of a given   particle or small group of particles undergoing  some change of state that transmutes, teleports or   changes them. There’s a very remote chance that  a whole bunch of hydrogen atoms could fuse in   exactly the right way to form a single molecule of  chocolate. It’s a tiny chance, but it’s a finite  

one, and thus it happening twice also has a finite  chance, though significantly smaller. The same   is true of it happening a quintillion times in  exactly the same place, with all the appropriate   textures, to form a perfect bar of chocolate. Although, those random particle interactions   would still be spitting out other particles,  or radiation. So someone spontaneously turning  

into a big chocolate statue of themselves  wrapped in gold foil ought to see the area   heavily irradiated to the point of looking  like a small nuclear bomb went off.   However, nuclear detonation or fatal irradiation  relies on those particles being absorbed by nearby   matter. Since there is a finite chance any given  gamma ray or alpha particle of radiation might   be absorbed while traveling in any given medium  for a given distance, there is a finite chance it   will not be absorbed, thus not contributing to  causing cancer or a thermonuclear shockwave.   There is also a finite chance that nearly  every particle of radiation produced in the   event will travel vast distances before being  absorbed or decaying too. Essentially there’s a   finite chance a nuclear bomb could detonate and  do no damage to the area at ground zero because   none of the particles of energy produced  randomly hit anything on their way out.  

This is the craziness that one has to  consider when dealing with a multiverse.   There’s a finite chance you could be sitting on  a nuclear bomb when it detonates and not die,   and there’s a finite chance that bomb will  instead turn into several thousand cheeseburgers.   There’s also a chance that all the energy  released in that transmutation, which ought   to exceed even a normal nuclear detonation,  won’t kill you, instead allowing you to enjoy   one of those tasty Quantum Cheeseburgers. If this seems insane, it only gets worse.  

Since there would be a near infinite number of  uninhabited Earth-clones, there should also be   a near infinite number of worlds where humanity  - or something like it - would also exist. And a   near-infinite number of such groups of humans  who also want to colonize all those worlds.   This is exactly what Isaac Asimov considers  in his short Story “Living Space”. Humanity   invents a way to peek at other empty versions of  Earth and colonizes them, sort of. Most are just  

colonized by a single family, as the worlds  are so abundant everyone can have their own.   In one case, they bump into a world where  it wasn’t actually entirely uninhabited,   but it turns out to simply be colonists from  another reality who also saw it as empty.   They then worry that there are a ton of these  societies, and that each is probably only   checking to see if the planet has a big and  obvious civilization, so that likely many of   the worlds they’ve colonized might also  have other colonists in some small spot   elsewhere on the planet. While they’re busy  considering the issue of some of their colonists  

eventually bumping into other colonists from other  Earths, and speculating on the idea of alien life   finding its way to their homeworld, a colonist  enters to complain about weird red creatures   with tentacles peering in through his windows  on his home in one of the colonized realities.   This raises the worrisome notion that  someone might invade your reality,   or that aliens in some reality might find  Earth and invade all of its realities,   or that something inhuman might evolve on  a copy of Earth, and invade elsewhere.   Truth be told, this isn’t actually as big a  problem as one might initially think. First,   it’s impossible to invade all possible realities,  since there’s always a reality where an invasion   did not occur. Second, the act of invading a world  would subsequently create additional realities  

where something goes wrong in an infinite number  of ways, or where the invasion was called off,   and so on. And lastly, the entire concept is that  there is a Universe for any possible combination   of the available particles, so if you can actually  add or subtract mass or energy from one universe   to another - in other words to travel there - then  that alters the number of available Universes.   Indeed you not only have a whole array of  different Universes with one more or one less   atom, or one quadrillion more or less, you  have to have an additional reality for each   moment and location in which a Universe  could gain or lose mass from another one.   The multiverse needs only interest us from a Fermi  Paradox standpoint if such travel is possible,   and since we can only detect or see things by  sending a particle of light or some parallel, you   can’t look at them or detect them or communicate  with them unless you can exchange energy in some   way. Even if you found a clever way to get around  this by only exchanging information in a way that   doesn’t move mass or energy, the simple act of  sending the information is changing the state of   something on both sides, which amounts to another  new reality, or rather a whole new set of them for   each possible combination of data you could send,  and each place and time you might send or receive   it, who sees it, and so on. If you find this  all confusing, don’t feel bad, it really is.   Essentially if travel is somehow possible, you  should have at least one additional Universe for   each possible travel scenario for each pair  of Universes, or indeed for each possible   combination of various Universes connecting to at  least one other, multi-multi-verses as it were,   and thus should never have to worry about running  out of possible Universes to send colonists,   in fact you are arguably getting infinite  combinations splitting at infinitely small rates   of time. I’m also not sure it would matter if two  identical copies of me from different realities  

happened to step onto the same place and  time onto identical versions of Earth,   but there should be a unique reality for each  person stepping onto each possible planet,   plus more for each combination of  accompanying people and equipment.   Perfectly identical repeat events, down to every  atom at the exact right nanosecond, may represent   two different universes anyway, but I’m not  sure how you could tell or if it would matter.   Now one thing that comes up in contemplating  colonizing parallel universes in fiction is that   they randomly jump to worlds and explore them,  but if they like them they can dial the planet   back up again. This is rather problematic though  because assuming there was some unique identifier  

for each reality, the equivalent of a phone  number, that code would be so long that even   stored digitally it would be impossible to work  with. It is possible the code might be relative   rather than absolute, how far and in what  direction of your own reality it is, though   I’m not sure you could do that, since there might  be multiple pasts that result in a given reality,   not just futures springing from it,  and there’s still a lot of realities.   Exactly how many realities there would  be in a Multiverse is hard to pin down,   but the approximate number typically kicked  around for our Observable Universe is 10^10^77.   To clarify that, that is a 10, followed by 10^77  zeros, or ten followed by a hundred thousand,   billion, billion, billion, billion, billion,  billion, billion, billion zeros. Which means   any given reality phone number you are dialing  has that many digits. Your typical book has  

around a million digits in it, your typical  modern harddrive, about a million times that,   so if we used every harddrive on the planet,  we might only need a billion, billion, billion,   billion, billion, billion times that  many to store a single Universe-code.   In fact even trying to dial those numbers in  as some stream of data in some period of time   shorter than geological times ought to require  passing data through a conduit with such speed   and density that it ought to form a black hole.  Which to be fair is not necessarily an issue,   given that most notions for traveling to other  Universes tends to involve modified black holes   or wormholes to do it. It would be interesting if  the method of making a gateway to another reality   involved assembling a micro-blackhole  gateway to it composed specifically of   digits of its address sent in packets of  energy. If any writers listening to this   feel like incorporating that as a novel form of  wormhole travel, feel free to steal the idea.  

So it ought to be impossible to even keep a phone  book of Universe addresses or dial them, but maybe   we can come up with a way, and it's not that big  a stretch compared to the stretch we already have   to make to assume there’s an actual way to  travel to these realities. It makes interstellar   or intergalactic travel seem both vastly easier  and vastly less desirable all at the same time.   So what does this all say  about the Fermi Paradox?   Well that’s tricky since our conclusion would  depend so much on the specifics. For example, if   you can pretty much open up a portal to clones of  our Earth, you can presumably also open portals to   parallel realities where Earth is a few minutes or  hours either ahead or behind in its current orbit,   and listen for SETI-style radio signals  without the noise of a planet in the way.  

Or ones where Earth was Mars-Sized, or orbited  a red sun, or both. The point being, you could   rapidly flick through billions of possible  Universes listening for loud radio signals in   our area of space, while simultaneously looking at  various weird combinations of stars and planets,   until you get a pretty good idea of where life  tends to pop up. If you have this capability,   you ought to be able to get some useful answers  about the Fermi Paradox rather quickly.   This is often the case with the Fermi Paradox:  if you actually possess a given technology which   would influence it, you also get a pretty good  idea of how relevant it is to the possible answer.   As an example, if we invented a cluster  of technologies that make it very easy   to get into space, and build big spaceships  with internal environments able to survive   centuries of travel in interstellar space, then  we’d know that other folks could have done it too,   so Fermi Paradox Solutions which rely on  interstellar colonization not being possible,   or on species killing themselves off before  they manage it, no longer look as plausible.   Incidentally, those are examples of what  we call Late Filters of the Fermi Paradox,   and indeed those two in particular are  usually considered the big Late Filters,   a capacity and desire for interstellar travel,  and successfully surviving long enough to do it.  

On the other hand, travelling through a multiverse  also undermines one of the critical assumptions   behind the Dyson Dilemma, which looks at how we  can assume there are no advanced civilizations in   our galaxy if certain conditions hold true, three  of which are that space colonization is possible,   that growth is desirable, and that space  colonization is the most attractive path   for that growth. If they have an option available  like colonizing the Multiverse by just stepping   through a doorway, then that’s what they do. Even those who want to practice terraforming,   or find non-Earthly conditions, are going to  pick a version of Earth that suits their needs.   There should be Multiverses where Earth has less  gravity, or is bigger, or has a double planet   instead of a Moon, that reality where Venus got  bumped into Earth’s orbital plane by a collision   and the two fell into a double planet lock.  That version of Earth with Saturn-like Rings,  

or that one where it recently had its  surface ripped off to form a Moon,   leaving exposed magma for you to easily mine  for metals for return to your own world.   So there’s just no reason to go out and  colonize space. Not even to escape from   entropy, since there should always be some other  reality with less entropy or even the ability to   run a heat engine through a gateway to  lower entropy here and raise it there.   On the other hand, you’d have virtually  endless resources to build spaceships with,   so you might still have folks doing  it for the sake of exploration.  

Now to address another big question:  if such travel were possible,   would aliens ever visit Earth? That is harder to say, but probably not, because   they’d feel an overwhelming urge to explore  space, the same as we would in their shoes.   They ought to be focused on exploring copies  of their own world, rather than visiting ours.   We might also want to consider if we’re just  talking about alternate histories or Universes   with different physical laws, because if there are  realities we can reach where the speed of light is   faster, then those would be the ones you would  expect folks to focus on exploring, or perhaps   even using to travel around their own Universe. A popular approach to faster than light travel in  

science fiction is to use some dimension  or universe congruent to your own,   where either travel is faster and easier or  space is smaller, making for a shorter distance   to travel. You pop in, travel, then pop back out  to our Universe. Think of Hyperspace and its other   analogies in various sci-fi settings. Such being  the case, we might be in a type of Universe folks   don’t bother traveling to or exploring much  because it's harder to travel in and explore.  

Or fatal, you might be able to extract energy  from some place with different physical laws   but by and large even a tiny change in physical  constants should make you explode or implode.   We also have to remember that in the  context of a Multiverse, where every   possible reality can exist, there must always  be places where a given event does not occur,   so there would always be ones in which no other  aliens ever exist, or choose to visit if they   do. Indeed, that’s another Isaac Asimov story,  where people who can choose possible timelines   pick one for humanity where humans are the only  intelligent species to arise in the galaxy.   You can never explore or colonize the entire  Multiverse since it is by definition every   possible scenario and that means there’s always  a bit of it you haven’t explored, colonized, or   conquered, and while you shouldn’t think of events  spawning new universes, in this sense of them not   having previously existed, conceptually if there’s  a reality where the aliens decided to invade,   there’s one where they did not too, there’s one  where they visit on Tuesday and one where they   visited last year and ten thousand years  ago and never but there should always be   an equal or greater number where they did not. How about that scenario where the aliens are from   Earth, but just a different copy, one different  enough we would call them alien not human?   Same premise. If I’m jumping to another world,  there’s a reality where I arrived at that given  

time and place and its twin where I did not,  and one for each scenario where I arrive at a   given time and a given place, where I stepped  out in Dallas, Texas on January first and   another where I exited in London on March 2nd or  Paris in 1903, and one for each of those option   where you did, or where an alien did. But there  would be vastly more where it did not happen.   Just because there are a near infinite number  of worlds where you or someone nearly identical   to you is alive, doesn’t mean there are  not vastly more where you’re not there.   There should be worlds where intelligent races  exist and travel to copies of their world   different enough and inhabited so that it’s  basically alien contact, but these ought to   be a tiny minority of them. While it's hard to  run the numbers, it ought to be very improbable  

that you’d ever dial up an inhabited world. If you  randomly dial places, then presumably very nearly   all of them don’t even have anything resembling  Earth there, but mostly because it's a dead lump   or empty space. If we assumed some sort of  congruity, like being more likely to dial   up versions of Earth similar to our own, then  for it to be inhabited by something human-smart   but distinctly in-human ought to be unlikely, as  that would imply some evolutionary divergence a   long time back, not a minor change. Though it  would depend on how that congruity happened,   and while it strikes me as a fun thing to  contemplate for a science fiction story, it would   likely take us entirely into that realm, and away  from even the remotely-possible science-fact.   Multiverses and travel to them is at least in the  realm of science, even if it’s near the fringe.   Though I would emphasize that we don’t know such  places exist nor have we any idea how we could   travel to them if it's even possible. Again,  the Many Worlds Interpretation is one of many,  

Schrodinger’s Cat and the Copenhagen  Interpretation being the other popular one, and   they aren’t both true, it’s just a question of if  either is, or if they’re both wrong. There’s zero   evidence to suggest that Many Worlds is right, and  the same is true of our other Multiverse concepts,   and so far we’re not even sure how we might  design an experiment or tool that could check.   This a fascinating option though, and one that  would have very unpredictable consequences for the   Fermi Paradox. We only explored a handful today  and, as mentioned, we explored some other related   concepts in our episodes Alternate Realities &  Parallel Universe, Infinite Improbability Issues,   and Aloof Aliens, which considers options  like alternate physics in more depth.   I’d say that the key take-aways are that more or  bigger Universes don’t necessarily exacerbate the   Fermi Paradox, as it requires that they be able to  reach us. And bigger means more numerous, but not  

necessarily more dense. In a multiverse scenario,  aliens would absolutely exist, and absolutely have   visited Earth, but it doesn’t necessarily mean  they came and visited our Earth, or that they   exist in our area of the Universe, or Multiverse.  It may even be that our universe is the case where   nobody else is there, and nobody decides to visit,  in which case we would never even know.  

So we were talking about Multiverses and the Many  Worlds Interpretation of Quantum Mechanics today   and if Many Worlds is right, then on one of them  there’s a version of you and I who both picked   up and understood Quantum Mechanics with ease,  but for most you probably found the topic as   counter-intuitive as I did when first learning  it and for that matter often still find it.   When things get small, things get weird, and if  you’re looking for a creative and interactive way   to learn about the topic, there’s an excellent  course on Quantum Objects over at Brilliant.   Memorizing formulas and listening to lectures  isn’t the best way to learn any topic, let   alone Quantum, and our friends over at Brilliant  understand that. Brilliant is a website and app   built off the principle that you learn best  while doing and solving in real-time. Jump   right into solving problems and be coached  bit-by-bit until, before you even realize it,   you've learned a new subject in STEM. We have a ton of research telling us what  

the best methods for learning are but it probably  won't’ surprise you that the most critical part of   learning is that you have to do it. You learn  best while doing and solving in real-time,   and Brilliant’s website and app  are built around that principle.   You won't need to memorize long messy  formulas and endless facts — just   pick a course you’re interested in, like  Quantum or Computers or Quantum Computers,   and get started. If you get stuck or make  a mistake you can read the explanations   to find out more and learn at your own pace. Brilliant has something for everybody — whether  

you want to start at the basics of math, science,  and computer science, or dive into cutting-edge   topics like Cryptocurrency or Quantum Computing,  and they do it all in a fun and interactive way.   If you'd like to join me and a community  of 8 million learners and educators today,   click the link in the description down  below or visit   So that will finish out April  but May will be jammed packed,   as we look at Biotechnology next week  and how it will impact our civilization.   Then we will move on to Alien Languages and how to  decode them, and later in the month we’ll discuss   Laser Pistols, Lightsabers, Arcologies, and Solar  Flares and their impact on the Fermi Paradox.   If you want alerts when those and other episodes  come out, make sure to subscribe to the channel,   and if you’d like to help support future  episodes, you can donate to us on Patreon,   or our website,, which are  linked in the episode description below,  

along with all of our various social media forums  where you can get updates and chat with others   about the concepts in the episodes and many other  futuristic ideas. You can also follow us itunes,   Soundcloud, or Spotify to get our  audio-only versions of the show.   Until next time, thanks for  watching, and have a great week!

2021-05-04 12:49

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