Are There an Infinite Number of Charlies?

Charlie McDonnell is a phenomenally successful YouTube blogger, with more than 2 million subscribers. And from time to time he likes to wrap his head around complicated topics in space and astronomy.

In this short video, Charlie tackles the implications of what it means to live in an infinite Universe. If the Universe is truly infinite, and there are a finite number of ways that matter can be configured, then if you travel far enough, you will run into duplicates.

Out there, somewhere, there are an infinite number of Charlies. And an infinite number of you and me.

Of course, if we life in a finite Universe, then just forget about everything that Charlie just said.

Here’s the thing. Astronomers have calculated that the Universe is at least 91 billion light-years or so across. Beyond that, they just don’t know if it’s finite or infinite.

If you want to chase down this rabbit hole even further, check out this older video from Numberphile on a similar topic. With these two videos under your belt, you should just barely be able to wrap your head around the concept of an infinite Universe.

20 Replies to “Are There an Infinite Number of Charlies?”

  1. Am listening to radio meteors (Pac. Coast Nebula overhead) via spaceweather while I type… here come the Perseids!

    Like a meteor, Charlie seems to leave a bit of a plasma trail in his wake? Bright and energetic, I hope he has a chance to ‘live long and prosper!’ Can he vote yet? Heck, somewhere he’s President!

  2. The occurrence of another person just like me or you involves certain prospects in bubble nucleation regions or pocket universes in the multiverse. There is the prospect that this is connected to the many worlds interpretation (MWI) of quantum mechanics. Each of these copies are identical up to some elementary quantum event that leads to decoherence. These copies are then generated by this eigenbranching in MWI. Before an elementary quantum event the two copies are in fact on and the same โ€œworld.โ€

    I am not entirely sold on this idea. For one MWI has issues with contextuality, or rather noncontextual basis setting in QM. This also potentially muddles up multiverse concepts with a quantum interpretation that is not testable.


    1. You’re mixing up the various different infinities.
      1. If THIS universe is infinite, then each arrangement of atoms is repeated an infinite # of times. That’s the article topic. The duplicates are really far away though. ๐Ÿ™‚
      2. If the Many Worlds quantum interpretation is true, regardless of how big THIS universe is, there are an infinity of yous and everything else spun off every Planck time interval. They’re just inaccessible and undetectable in “parallel” universes. I prefer to call them orthogonal universes.
      3. If there is an ongoing process of continually created bubble universes popping off like with our Big Bang, then there’s an infinity of universes, each with their own physics constants, etc. and of course the obligatory infinity of universes duplicating ours.

      1. And if both are true, then you’ve got an infinite number of orthogonal universes, each of which is infinite. Turtles all the way down.

  3. Charlie’s definition of ‘duplicate’ has not defined the level of coherence; for fun, ie whether all the referenced duplicates are simultaneously duplicating position, activity, age etc or whether each duplicate Fraser Cain is also friends with Dr Gray ;). Would their email addresses and tooth fillings be the same? ๐Ÿ™‚ It appears that life adds a random-appearing set of values to the thing.

    I’m skeptical of the infinite eternal universe idea.

    1. Of course, if we live in a finite Universe, this goes right out the window. The Universe has to infinite, or really really really big to repeating volumes of space.

      1. As an aside, it appears this duplication idea has also predicted complex ET life.

        Going with the infinite universe idea for a moment, one still wonders why these replications would occur at the complex levels of say, duplicate Fraser Cains and bfmorrises, when there is so much empty/nearly empty space that satisfies the supposed inevitability of matter configuration duplication.So, it seems there is duplication, but it is in the form of empty/nearly space.

        For Charlie’s idea to be viable, wouldn’t the infinite universe have to be filled with matter throughout? Perhaps it is space/time that is infinite, but not matter configurations.

  4. Sorry for the noob question, but I was wondering:

    If the Universe age is ~13.8 billion years, how can it span for ~91 billion light-years?

    Considering that you are in one “edge”/”border” of the universe and it expands homogeneously since big bang, the other side shouldn’t be at ~27.6 billion light-years from you?

    This means that the universe expands in a speed faster than light, and that’s why we can have this difference of ~63 light-years?

    I want to understand this better, can you recommend some reading about this subject?


  5. Charlie’s implied assertion that there would be, on average, 10^30 copies of any person in a googolplex-sized universe works on the assumption that the quantum states are filled randomly. They are not, of course, and in addition there are a huge number of quantum states that would be considered “equivalent” by his definition. There are 10^44 Planck time units in each second, so conceivably there are 10^44 versions of quantum states that would match you within just the past second (unsure how rapidly quantum states change, but you get the idea).

    And given that much of the evolution of humans is very deterministic, not random, this greatly limits the total possible quantum states possible in a human-sized form. For example, any impossible biological forms would not exist because these forms exist within a very narrow template of possibilities (with respect to the total possible variations of quantum states).

    All in all, it doesn’t even remotely take a googleplex-sized universe to create duplicate humans.

  6. Prof. Max Tegmark is an astronomer who has dared to speak publicly about this topic. We CAN know something about if the universe is infinite or finite, by looking at the bakground radiation from the Big Bang. Measurement shows that theuniverse is infinite to the best precision we can measure today. But your copy will likely be at a distance so large that space between us expands faster than the speed of light, so we can never affect each other in any way.

    1. An infinite universe is a philosophical problem fรถr science. All possible combination of events happen somewhere. So observation breaks down to observing where we are, rather than observing for example how photons in general behave in the entire universe. Another place in the universe is such that all six sided dice land with the 6 turned upwards, statisticians have a tough time formulating a logical theory there…

  7. The problem with this infinite number of Charlies is that if each one is living out their lives slightly differently, it would very, very, very, quickly add up that in a couple of generations, you will already have very different outcomes. That girl he decided to ask out? They might get married and have kids that would be dramatically different from the kids he would have in this universe.

    And if that were the case, then it’s pretty much impossible for him to have the exact same set of ancestors in another universe. Or another part of this universe. Extrapolate over the course of 4.5 billion years, and you’ll quickly realize that even life here on earth, starting from *exactly the same parallel beginning*, would be completely alien to us. It probably wouldn’t even evolve bipedal, big-brained creatures with opposeable thumbs. Or mammals, for that matter.

    As we’re slowly discovering, our own solar system is in itself an extreme oddity. So while that 0.0000000000000012% chance of any intelligent life at all evolving in our own galaxy makes sense over the course of 3 billion stars, the probable number of civilizations in our own galaxy is still quite small, especially considering billions of stars. The probability of an exact copy of our own present world being created would be hundreds of trillions of times (or even more!) smaller. This means that the likelihood of a parallel Chris existing anywhere else in the observable universe (trillions of galaxies) is at best, somewhat close to 100%. It’s extremely unlikely that more than two exist (including this one).

    1. You miss the point completely. IF the universe is infinite (not the paltry, tiny observable universe) Charlie copies abound. So do dinosaurs, trilobites, mammoths and all kinds of exotica we cannot imagine. Now, try to get there…

    1. This is not something we know. It is only something we can extrapolate. In fact, it is pretty certain that is it is something we can not know.

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