The Way You Think Everything Is Connected Isn’t the Way Everything Is Connected

I hear it from older people, mostly.

“Oh, I know about quantum physics, it’s about how everything is connected!”

“String theory: that’s the one that says everything is connected, right?”

“Carl Sagan said we are all stardust. So really, everything is connected.”

connect_four

It makes Connect Four a lot easier anyway

I always cringe a little when I hear this. There’s a misunderstanding here, but it’s not a nice clean one I can clear up in a few sentences. It’s a bunch of interconnected misunderstandings, mixing some real science with a lot of confusion.

To get it out of the way first, no, string theory is not about how “everything is connected”. String theory describes the world in terms of strings, yes, but don’t picture those strings as links connecting distant places: string theory’s proposed strings are very, very short, much smaller than the scales we can investigate with today’s experiments. The reason they’re thought to be strings isn’t because they connect distant things, it’s because it lets them wiggle (counteracting some troublesome wiggles in quantum gravity) and wind (curling up in six extra dimensions in a multitude of ways, giving us what looks like a lot of different particles).

(Also, for technical readers: yes, strings also connect branes, but that’s not the sort of connection these people are talking about.)

What about quantum mechanics?

Here’s where it gets trickier. In quantum mechanics, there’s a phenomenon called entanglement. Entanglement really does connect things in different places…for a very specific definition of “connect”. And there’s a real (but complicated) sense in which these connections end up connecting everything, which you can read about here. There’s even speculation that these sorts of “connections” in some sense give rise to space and time.

You really have to be careful here, though. These are connections of a very specific sort. Specifically, they’re the sort that you can’t do anything through.

Connect two cans with a length of string, and you can send messages between them. Connect two particles with entanglement, though, and you can’t send messages between them…at least not any faster than between two non-entangled particles. Even in a quantum world, physics still respects locality: the principle that you can only affect the world where you are, and that any changes you make can’t travel faster than the speed of light. Ansibles, science-fiction devices that communicate faster than light, can’t actually exist according to our current knowledge.

What kind of connection is entanglement, then? That’s a bit tricky to describe in a short post. One way to think about entanglement is as a connection of logic.

Imagine someone takes a coin and cuts it along the rim into a heads half and a tails half. They put the two halves in two envelopes, and randomly give you one. You don’t know whether you have heads or tails…but you know that if you open your envelope and it shows heads, the other envelope must have tails.

m_nickel

Unless they’re a spy. Then it could contain something else.

Entanglement starts out with connections like that. Instead of a coin, take a particle that isn’t spinning and “split” it into two particles spinning in different directions, “spin up” and “spin down”. Like the coin, the two particles are “logically connected”: you know if one of them is “spin up” the other is “spin down”.

What makes a quantum coin different from a classical coin is that there’s no way to figure out the result in advance. If you watch carefully, you can see which coin gets put in to which envelope, but no matter how carefully you look you can’t predict which particle will be spin up and which will be spin down. There’s no “hidden information” in the quantum case, nowhere nearby you can look to figure it out.

That makes the connection seem a lot weirder than a regular logical connection. It also has slightly different implications, weirdness in how it interacts with the rest of quantum mechanics, things you can exploit in various ways. But none of those ways, none of those connections, allow you to change the world faster than the speed of light. In a way, they’re connecting things in the same sense that “we are all stardust” is connecting things: tied together by logic and cause.

So as long as this is all you mean by “everything is connected” then sure, everything is connected. But often, people seem to mean something else.

Sometimes, they mean something explicitly mystical. They’re people who believe in dowsing rods and astrology, in sympathetic magic, rituals you can do in one place to affect another. There is no support for any of this in physics. Nothing in quantum mechanics, in string theory, or in big bang cosmology has any support for altering the world with the power of your mind alone, or the stars influencing your day to day life. That’s just not the sort of connection we’re talking about.

Sometimes, “everything is connected” means something a bit more loose, the idea that someone’s desires guide their fate, that you could “know” something happened to your kids the instant it happens from miles away. This has the same problem, though, in that it’s imagining connections that let you act faster than light, where people play a special role. And once again, these just aren’t that sort of connection.

Sometimes, finally, it’s entirely poetic. “Everything is connected” might just mean a sense of awe at the deep physics in mundane matter, or a feeling that everyone in the world should get along. That’s fine: if you find inspiration in physics then I’m glad it brings you happiness. But poetry is personal, so don’t expect others to find the same inspiration. Your “everyone is connected” might not be someone else’s.

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20 thoughts on “The Way You Think Everything Is Connected Isn’t the Way Everything Is Connected

  1. Gary

    “Defects of empirical knowledge have less to do with the ways we go wrong in philosophy than defects of character do: such things as the simple inability to shut up; determination to be thought deep; hunger for power; fear, especially the fear of an indifferent universe. These are among the obvious emotional sources of bad philosophy” (D. Stove, What is Wrong with Our Thoughts? =http://gerryonolan.com/public_html/stove/wrongthoughts.html)

    “Now, when we turn to the lowest existing savages, they are found to possess, in comparison with other apes, a considerable fecundity of ideas; constituting, on the one hand, a good stock of common sense, or knowledge of the properties and activities of the things and organisms around them, and of how to deal with them, which enables them to carry on the affairs of their lives: but including, on the other hand, a strange collection of beliefs about magic and spirits, which entirely misrepresent the course of nature and the effective population of the world. These latter beliefs, or imaginative delusions, hamper them in so many ways, waste so much time, lead them sometimes into such dark and cruel practices, that one may be excused for wondering whether their bigger brains can have been, on the whole, of any biological advantage to them in comparison with other anthropoids. Other anthropoids live by common sense. So do savages, and they have much more of it; but the anthropoids seem not to be troubled by magic and animism. We must suppose that the common sense of primitive human increased age by age, as he became more and more perfectly adapted to the hunting-life, and that at some stage his imagination began to falsify the relations of things and the powers of nature. These imagination-beliefs depend chiefly upon the influence of 1- Desire, 2- Fear, 3- Suggestibility, 4- Reasoning by analogy 5- Mental disease (epilepsy, insanity, swoon, catalepsy, schizophrenia,etc.). And at this stage imaginations, thus divorced from reality, began to greatly influence lycopithecus’ life.
    For thousands of years, humans have been subdued through imagination.” (Carveth Read, Origin of Man and His Superstitions).

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    1. Gary

      I highly recommned C. K. Ogden’s The Meaning of Meaning: A Study of the Influence of Language upon Thought and of the Science of Symbolism and Stuart Chase’s The Tyranny of Words. It’s a must-read for all scientists, esp. physicists.

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  2. giuliohome

    All your articles are always very interesting. I’ve tried very hard to understand the engagement and – even though it is clear that it doesn’t allow superluminal signals (and only to such extent it doesn’t violate locality) – it seems to create a sort of tunnel in some invisible dimensions… the metaphor of the coin doesn’t really hold and – aside from the impossibility to propagate a signal – it appears that a wavefunction collapse due to a measure of a bit in one place would immediately produce a “flip” of the entangled entity in a remote part of the universe… what’s the nature behind the phenomenon is quite unclear. Then we know that (for example according to loop quantum gravity) time is an illusion, Like space. I’m afraid that particle physicists shoud recognize that their theory are limited somehow and there is something missing they can’t grab. I guess they idolize Einstein and quantum fields like gods: it’s their religion ;)) I’m joking sorry

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    1. 4gravitonsandagradstudent Post author

      (Assuming the “joking” part is just the last couple sentences and not the rest 😛 )

      If you think about things in terms of wavefunction collapse, then yeah, if you measure one side something instantaneously changes on the other side. Here’s the thing though: you can’t tell whether the wavefunction of the one on your side has “collapsed” without measuring/collapsing it yourself, at which point you still can’t tell if the other person “collapsed it first”. So whatever sort of “instantaneous change” is happening, it’s not something you can do anything with, or measure.

      If you haven’t read the article I linked about decoherence, that might make you a bit more comfortable with things. Essentially, it’s suggesting that one can think of “measurement” as what happens when you try to only look at one part of a larger entangled system.

      That said yeah, entanglement is weird. It’s weirder than a coin cut in half. But a big part of why it’s weirder is because it’s a “coin cut in half” with no hidden variables, a “coin cut in half” that you can’t predict. That’s already weird, and a lot of the remaining weirdness flows from that.

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      1. giuliohome

        Your reply is wonderful – I’m serious. The paragraph starting from “If you think about …” and ending with “… or measure.” is literally perfect, I couldn’t agree more! That would make me think that everything is very simple and it is just a “coin cut in half” but then devil hides in details and some complexity arises … well, I’d love to discuss this with you but I want to bother you with lengthy comments… Years ago -i tried to express my doubts about Bell theorem in a forum but unfortunately they closed my topic and I was unable to further reply https://www.physicsforums.com/threads/bells-theorem-in-nlab.839875/ So again, thank you for your kind answers here! but I don’t want to abuse your patience 😉

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        1. giuliohome

          Problems arose when I started reading “Quantum Mechanics” of Susskind. In the chapter about entanglement he insists that something has no classical analog even if the situation looks similar to the classical example involving (in his words) “Charlie and his two coins”. The point is the anticorrelation if you “suppose that instead of measuring the z components of their spins, Alice and Bob measure the x components.” And now I spare you the math calculations 😉 and I close here!))

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          1. 4gravitonsandagradstudent Post author

            Yeah, that’s where the “there are no hidden variables” feature sneaks in, essentially. With one component only you really can’t tell the difference, but as long as you have two different measurements you can do then the difference appears, if only when you examine many cases and look at the statistics. (Standard Bell explanation basically.)

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            1. giuliohome

              But I’m still convinced that the “no hidden variables” standard explanation is somehow wrong: the point (from an interesting physics SE post that is surprisingly original and not following the mainstream) is that you can exclude non contextual hidden variables but it’s obvious instead that the any measure has a disruptive effects … so one should look for contextual hidden variables … Read this answer: https://physics.stackexchange.com/questions/213985/can-someone-clarify-whether-the-recent-experiment-closing-all-remaining-loophole/214010#214010 about the fact that loop holes of Bell theorem are not really closed (what do you think?)

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              1. 4gravitonsandagradstudent Post author

                I feel like a lot of attempts to introduce hidden variables confuse epistemological conceits with physical ones. So for example, complaining about the “nondeterminism” of the experimenters in the standard Bell setup, or proposing that you need to take into account the state of everything involved and thus no two experiments are the same (tied to things like superdeterminism). In both cases, it’s taking a universal feature of scientific explanations (the ability to ask “what if”, abstracting away things that shouldn’t matter) and treating them as features of the proposed physics. That makes me leery of that sort of post.

                That said, this is rather deep in the weeds of QM interpretations for me, and as I’ve mentioned in the past this isn’t really my subfield.

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  3. Giotis

    Well, the particles we are made of are excitations of the same field, aren’t they?

    In that sense we are all connected☹

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  4. Clayton

    Sorry to quibble, but I think the penultimate example [[[ <Sometimes, “everything is connected” means something a bit more loose, the idea that someone’s desires guide their fate, that you could “know” something happened to your kids the instant it happens from miles away. This has the same problem, though, in that it’s imagining connections that let you act faster than light, where people play a special role. And once again, these just aren’t that sort of connection.> ]]] misses the point. Light travels quite fast, but if something happens to a distant loved one even causality-preserving signals don’t exist unless they are delivered through standard technology. The point is that we know all the forces at terrestrial energy, and hence we know all the possibilities for signal propagation (except for very weakly coupled new force carriers). Bremsstrahlung of a gauge boson during a moment of crisis can’t communicate anything special between loved ones.

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    1. 4gravitonsandagradstudent Post author

      Fair enough. FTL isn’t an essential part of those sorts of misunderstandings, indeed. Rather, it’s the idea that the sort of “connections” known to physics place people in a unique role, rather than being based on the same physical fields that are in everything.

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  5. Pingback: Is Everything Connected? Not really… | The Drinking Water Advisor

  6. Wyrd Smythe

    I’ve wondered what the (useless) simultaneity of entanglement says about how Special Relativity skews time slices. What happens when two entangled particles are considered in different reference frames?

    I’ve been wondering, in general, a lot about time recently. The serious strangeness of “now” and what it implies. If we live in a block universe, we’re somehow all riding “trains” (at different rates) through it. If the future ISN’T fixed, “now” is the edge of a loom weaving past from possibility. Either way it begs an explanation. (Useless, I know, but most of my questions are seriously ontological.)

    WRT FTL, I love the bit I saw somewhere: Special Relativity, Causality, FTL…. Pick any three. 🙂

    [As an aside, I’ve been working with SQLite recently, and I’m charmed by their motto: “Small. Fast. Reliable. Choose any three.” (And, boy, are they right!)]

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    1. 4gravitonsandagradstudent Post author

      The uselessness of the connection is precisely how you avoid a contradiction when you consider two entangled particles in different frames, actually. If you could do something with the connection, then you’d end up with two events that, per special relativity, can be in different orders depending on the frame, influencing each other, and there’d be no way to make sense of it. Luckily though QM avoids the problem.

      If you haven’t seen it, you might be interested in this article on time. I wouldn’t say it’s a particularly mainstream position, but at least it should give an idea of what sort of setup you need to have a “loom” that makes sense.

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      1. Wyrd Smythe

        The uselessness lets the math work, but I still try to wrap my head around the ontology of entanglement simultaneity in the context of SR. On some level the way SR orders events depending on your motion almost seems explainable solely on light’s motion — how long it takes information about events to reach you.

        But the example of the long fast train fitting inside the short tunnel seems to suggest more is going on. The train seems “rotated” as you might rotate a ruler held out lengthwise. As you do, you see the ruler foreshortened — it appears shorter to you. Thus you can hide a three-foot ruler behind a one-foot object. In SR the rotation seems to be in time — the leading end “rotated” backward, the trailing end forward. The train fits because the front end hasn’t reached the exit of the tunnel and the back end has already passed the entrance.

        Assuming one actually could trap a long object in a short space — literally block both ends demonstrating genuine physical shortening of length — then we’re beyond mere optical effects of how long it takes light to reach an observer. And as I said, the ontology of this fascinates me!

        Thanks for that link! Loved the article! (I like Quanta, they have some excellent writers there, some good in-depth stuff, and they don’t kill you with ads.) I really like the way Maudlin thinks, and I agree very much with his view. Not mainstream, as you say, but remember I’m the guy holding out for smooth gravity and time. I hope the reconciliation isn’t quantizing gravity but fitting QFT into a smooth spacetime background. Not at all mainstream. 🙂

        Maudlin strikes me as a great example of why philosophy is so important in science. It’s one thing for physics to be non- or even counter-intuitive, but it shouldn’t be utterly preposterous. The idea, for example, of multiple time axes is preposterous, and Maudlin does a great, very clear, job of saying why.

        And I fully agree: I’ve never really bought the idea that physics is neutral about the direction of time. I could go on… many points in that article had me grinning ear-to-ear! Right On, Brother! 🙂

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  7. Paul Squassoni

    I am not a trained scientist, but for a while now I have thought that everything in spacetime must be connected for reasons from several different perspectives:
    1. The existence of entanglement implies that particles in space-time are connected through something that must be outside of space-time, since no space-time agency exists that permits entanglement.
    2. The unification of forces is accomplished mathematically through higher dimensions, implying that there are more dimensions than the 4 dimensions of space-time. Additional dimensions would pretty clearly connect at least the 3 spatial dimensions.
    3. M theory proposes 11 dimensions, another possible way of connecting space-time.
    4. Calabi-Yau manifolds strongly suggest that space-time arises out of a more complicated, and probably unifying, set of dimensions.
    5. The Schrodinger equation is almost always used in a restricted manner, but there seems to be an implication that with enough information, a single wave function would describe all of space-time.

    I know each one of these is a very complex subject of its own, but if my speculation is seriously awry, I would love some enlightenment! Please feel free to email me and take this offline from your blog.

    Btw, I am delighted to have found your blog again. I was truly sorry when my link to 4 gravitons and a grad student stopped working.

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    1. 4gravitonsandagradstudent Post author

      For 1., this is sort of the point I’m making here: entanglement does “connect” everything, but in a very different way from most other sorts of connections. It’s more similar to the connection of two people sharing the same name than the connection of them being in the same place. That’s not to say there isn’t a relation to spacetime, but it’s important to be careful about what kind of relation it is.

      For 2-4, extra dimensions don’t necessarily lead to more connectivity in the other dimensions. Think about the old example of an ant on a wire: for us, the wire has one dimension, but since the ant can move around it it sees two dimensions. Despite that, it’s no easier for the ant to move from one place to another on the wire, the extra dimensions doesn’t make points on the wire any more connected.

      For 5, having a single description (say in terms of a many worlds-style wavefunction for the universe) is yet another kind of connected, and also one that doesn’t necessarily let you do all that much. You can describe an entire country in one map, but that doesn’t make it easier to travel across it.

      So in general, yeah, these are ways the universe is connected…but they’re not the same sort of connection, and thus in the end it all depends on what you want your connection to do.

      Sorry that your link stopped working. I had WordPress forward people from the old 4gravitonsandagradstudent address to the new 4gravitons one for a few years, but they charge money for that, and after a few years I figured most people would have switched their links. Sorry you slipped through the cracks there!

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