Physics Mistranslated: Spooky Action at a Distance
This summer I mostly spent moving from New York to California, but after getting settled in I’ve had a couple weeks now to start on actually writing this book. The first chapter is called “Physics Mistranslated” and is essentially a greatest hits reel for some of the worst physics articles I’ve seen so far this millennium, along with my attempt at clarifying what went wrong with the translation from math to plain language.
About a decade ago, I saw a parody of New Scientist go around, which looked something like this (I couldn’t find the original and don’t know who created it, so I did my best to recreate it myself by modifying an original New Scientist cover in Gimp — if anyone knows if I’m breaking any copyright laws or other rules here, please let me know and I’ll remove it). Of all the Internet memes I’ve seen, I think this has always kind of been my favorite. It captures perfectly the theme of the first chapter of the book, as well as my impression of New Scientist in general.
If it seems outlandish, it’s not so different from some of the actual New Scientist magazine covers (You Are a Hologram, Touching The Multiverse, The End of Spacetime, Darwin Was Wrong, How Your Mind Warps Time, Why We All Live in a Hologram) that have shown up over the years. New Scientist is notorious for getting the science wrong, feeding people bad explanations for things, and using sensationalist headlines to attract an audience. But the problem is far more widespread and affects in one way or another just about every science news outlet that has published stories about physics.
I feel a little bit more cynical than usual writing this chapter, as the focus is on the negative. A glimpse at what was poorly done and led more to confusion than understanding. I intend the rest of the book to be more positive, exciting, and inspiring. But it seems crucial to start by pointing out where past attempts at doing what I’m attempting have gone wrong. And even moreso than popular books, magazine and news articles are a never-ending source of such failed attempts.
I spend a while on the speed of light, then move on to other topics such as the Large Hadron Collider, Black Holes, the Big Bang, and the Higgs Boson.
The most advanced part of the first chapter is a subsection of the section dealing with the speed of light where I respond to a 2015 Time magazine article entitled What Einstein Got Wrong About the Speed of Light , explaining how the phrase “spooky action at a distance” has been systematically distorted and abused in articles like this and gives a very misleading picture of the current state of knowledge in physics.
As I document in the part leading up to this, every couple years since 2000 (and probably before that too, although I haven’t checked back further) there is another news article that comes out proudly proclaiming the speed of light has finally been broken. Even though the speed limit that Einstein proposed in 1905, after 111 years, has never once been broken and there is no indication that it ever will be.
Most of the examples I give are relatively simple misunderstandings of Einstein’s theory of relativity (although in many cases, it’s just the headlines they choose that are intentionally misleading, and the article itself makes at least some effort to explain why that’s not really the case). Part of the reason that many articles make it sound as if this speed limit has been broken is a failure to clarify what words like “speed” and “travel” mean for waves, and to be clear about what precisely Einstein’s original speed limit forbids and what it doesn’t forbid. And some examples are just headlines that came out and then had to be retracted later (for example, faster than light neutrinos).
But for the case of quantum entanglement, the subject dealt with in the Time article, the source of confusion is a bit more subtle. So I’d like to summarize some of the main points I make related to that in this blog post.
According to Time:
You have to accept that two particles at opposite ends of the universe can be entangled in such a way that anything you do to one instantly affects the other. And you have to accept that the strictest, no-exceptions rule in all of physics — that nothing can move faster than the speed of light — may have some exceptions after all.
— Time magazine, 2015
There are multiple problems with this.
First, no you do not have to accept that anything can instantly affect something else at a distance. There are many interpretations of quantum mechanics, and instantaneous action at a distance happens in some of them but not others. The ones where it does happen are more on the fringe side; it is not a part of mainstream quantum mechanics as practiced and understood by most physicists.
And secondly, the phrase “nothing can move faster than the speed of light” has plenty of exceptions; most of them have been well known since Einstein’s time, and the ones that weren’t haven’t been nearly as interesting or as unique as the science journalists and their readers seem to think they are (why else would they keep hyping them every couple years?) The problem is, that phrase is a poor translation of an ironclad law of physics which has no known exceptions. A better translation of the rule that Einstein’s special theory of relativity established mathematically is “nothing can influence anything else faster than light”. Or even more precisely, “you can’t send signals faster than light”. This is always what the law has said when you read the mathematics, but because there are so many poor translations of the law floating around, when people hear things that contradict one of the bad translations they get excited and think it’s an exception. It’s not. And nothing about quantum entanglement allows an exception to this rule. That’s something all physicists agree on, regardless of their interpretation (even the fringe ones).
They continue on into their morass of confusion and obfuscation:
The idea that that could happen with no time lag at all was something Einstein dismissed as “spooky action at a distance” — and he wanted no part of it. But now, an experiment at Delft University of Technology in the Netherlands suggests that the great man’s objections notwithstanding, spooky action at a distance is real. And with that, the entire field of quantum physics gets a big boost.
— Time magazine, 2015
The experiment they are referring to was not surprising to anyone in the physics community, and I doubt many physicists found it interesting — I certainly didn’t, despite being very interested in the foundations of quantum mechanics, quantum information and interpretation. The idea that it gave a “big boost” to quantum physics is an outrageously false statement, as quantum physics has been an established and well-verified scientific theory for nearly a century now. This is like running an article in 2016 saying Darwin’s theory of natural selection gets a “big boost” because someone discovered a new kind of gene mutation.
Their claim that “spooky action is real” is premature at best, but likely just plain wrong. This is something a minority of physicists believe in, but the majority rejects as having no evidence to support it. I doubt there is a single person in the world on either side who changed their mind because of this experiment.
If it seems like I’m picking on Time, to be fair, the New York Times reported it in the same misleading way:
In a landmark study, [scientists] reported that they had conducted an experiment that they say proved one of the most fundamental claims of quantum theory — that objects separated by great distance can instantaneously affect each other’s behavior.
— New York Times, 2015
This has never been a claim of quantum theory, let alone a fundamental claim. Rather, it is a fringe interpretation that some people have of these kinds of experiments. At least in the case of the New York Times, they protected themselves from liability somewhat by prefacing their statement with “they say”, so that if anyone complains what they reported was untrue, they can pass some of the blame to the group of experimental physicists who presumably told them that. However, it should have been their responsibility to check with other physicists (preferably, experts on foundations and interpretations of quantum mechanics) to get their take.
The 2 biggest mainstream camps of physicists when it comes to how to interpret quantum mechanics (how to translate the mathematical equations into plain English) are Copenhagen and Many Worlds. Neither of them involve any instantaneous action at a distance. Nor do other similar mainstream interpretations such as Consistent Histories, Quantum Logic, or QBism (Quantum Bayesianism). Because they are so similar, it’s debatable whether the latter 3 are really separate interpretations or just useful clarifications of the original Copenhagen Interpretation. In addition to these mainstream camps, there are 2 somewhat more fringe camps of physicists who believe in theories which are also often referred to as “interpretations”. These other 2 camps are Hidden Variables (such as the deBroglie-Bohm pilot wave theory) and Objective Collapse (such as Ghirardi-Rimini-Weber theory and Diosi-Penrose theory). However, neither Hidden Variables nor Objective Collapse are interpretations in the sense I’ve defined the word. They are extensions and modifications of the mathematical structure of quantum mechanics itself, whereas all the others I’ve mentioned are simply slightly different ways of translating the same mathematics into plain language. And the Hidden Variables and the Objective Collapse camps are the only ones who believe in spooky action at a distance. Journalists should be more aware of this distinction, as both of these camps are completely speculative — there isn’t any empirical evidence that quantum mechanics needs to be modified or extended, nor is there any fully consistent theory worked out for how it would be. So far, the attempts at modifying or extending quantum mechanics have all fallen short. For example, Objective Collapse has run into major issues like energy conservation. And neither of them appears to be consistent with relativity. The people in these camps just believe that eventually there will have to be some kind of modification or extension of quantum mechanics because mainstream quantum mechanics does not conform to their philosophical intuitions about how theories of physics should work.
It’s often said that Einstein thought quantum mechanics involved “spooky action at a distance”. But this is misleading. He did use that phrase once, at the age of 68 in a private letter to Max Born. And he did have doubts about the mainstream Copenhagen interpretation of quantum mechanics. But those doubts were rooted mostly in his personal discomfort with the fact that quantum mechanics (at least in the form of Copenhagen) is only able to make statistical predictions about the future from the point of view of some observer, as opposed to providing an objective realist representation of reality as classical mechanics did. Informally, he summed up these doubts by saying “I at any rate, am convinced that He [God] does not throw dice.”, and Niels Bohr (chief architect of the Copenhagen Interpretation) responded with “Einstein, don’t tell God what to do!”.
Like most physicists, both in his time and now, neither Einstein nor Bohr believed that quantum mechanics required any instantaneous action at a distance. That was something primarily associated with Isaac Newton’s theory of gravity, which Einstein succeeded in removing from physics (by discovering that there was a deeper mechanism behind gravity which no longer required the spooky action at a distance postulated by Newton). The main point he was making to his friend Born in his personal letter to him was that even though the presently accepted interpretation of quantum mechanics was merely statistical, he had a dream that one day, quantum mechanics would be extended and “completed” with a fully realist deterministic theory. And yes, he did add that he expected this completed theory would be free from any action at a distance. This is the exact quote:
I cannot make a case for my attitude in physics which you would consider at all reasonable. I admit, of course, that there is a considerable amount of validity in the statistical approach which you were the first to recognize clearly as necessary given the framework of the existing formalism. I cannot seriously believe in it because the theory cannot be reconciled with the idea that physics should represent a reality in time and space, free from spooky actions at a distance. […] I am quite convinced that someone will eventually come up with a theory whose objects, connected by laws, are not probabilities but considered facts, as used to be taken for granted until quite recently. I cannot, however, base this conviction on logical reasons.
— Albert Einstein, 1947
Einstein’s opinion, viewed in hindsight, would usually be placed in the Hidden Variables camp. However, nearly all modern day Hidden Variables advocates have given up on a key assumption that Einstein insisted on, namely the “free from spooky action at a distance” part. (Nobel Prize winner Gerard ‘t Hooft is the only Hidden Variables advocate I’m aware of who still holds all of the opinions on quantum mechanics Einstein expressed here, but his interpretation is even further on the fringe.) Based on Einstein’s criteria — that quantum mechanics be realist, non-statistical, and free from any action at a distance — there is only one sensible interpretation which appears to satisfy all of these requirements: the Many Worlds Interpretation. However, instead of making it more complicated by adding additional postulates on top of Copenhagen (as Hidden Variables does), it removes a postulate making it leaner and simpler. Known among physicists as the Born Rule, this postulate is the prescription Max Born came up with for how to convert a quantum mechanical wave function into a statistical prediction. Because it removes this postulate, advocates of Many Worlds require that it be derived from the other postulates of quantum mechanics. Opinions vary within the physics community as to whether the existing derivations in the literature have been adequate or if they involve too much hand waving. Opinions also vary on whether this is a worthwhile project, as realism is not the only philosophical starting point for understanding science, and most physicists are perfectly comfortable with competing philosophies such as instrumentalism or pragmatism. (More on these in future posts.) Nevertheless, I think most people who have spent a significant amount of time trying to understand the foundations of quantum mechanics would agree that Many Worlds is the best hope of realizing Einstein’s dream of getting rid of the statistical aspect of quantum mechanics and restoring realism, if such a thing is your cup of tea.
Einstein’s informal personal remark to Born came 12 years after the more formal critique he made of quantum mechanics in the famous paper known as EPR (named after Einstein and the 2 postdoctoral students he published it with, Podolski and Rosen). The full title of it was Can Quantum-Mechanical Description of Physical Reality Be Considered Complete? Although many people today associate EPR with action at a distance, it was never mentioned at all in the paper. They didn’t even mention the more scientific sounding term “locality” (the principle that physical interactions can happen only between neighboring points in space rather than far away). Contrary to popular conception, this was just not what the paper was about. They state clearly the philosophical assumptions they start with (scientific realism):
In a complete theory there is an element corresponding to each element of reality. A sufficient condition for the reality of a physical quantity is the possibility of predicting it with certainty, without disturbing the system.
And they reason from these starting assumptions to the conclusion:
One is thus led to conclude that the description of reality as given by [quantum mechanics] is not complete.
The most mainstream opinion in the physics community today is that realism was not a necessary requirement for a scientific theory and therefore the conclusion doesn’t hold — quantum mechanics is already complete. People in the Hidden Variable camp, such as John Bell (the one who dug up and popularized the phrase “spooky action at a distance”) take the opposite approach and assume that the starting assumption was correct and that quantum mechanics still needs some unknown ingredient added to it in order to be complete. However, after Einstein passed away it has become clear that attempts to “complete” quantum mechanics by adding hidden variables will not be possible unless the locality principle he held so dearly is dropped. Locality was a hidden assumption in the EPR paper but was never explicitly stated — presumably because the authors viewed it as even more obvious and unassailable than the assumptions of philosophical realism that they did state explicitly.
However, there was also another hidden assumption in the EPR paper which was pointed out in 1956 by Hugh Everett (sadly, just 1 year after Einstein passed away so he would never know about it). Quantum mechanics is a tool that provides probabilities for different outcomes of each experiment. At the time EPR was published (1935) it was taken for granted by everyone that these different outcomes represented different possibilities for future events. But Everett introduced an alternate interpretation which involves slightly different language: perhaps it makes more sense to describe these different outcomes as different actualities rather than possibilities. Another way of stating this hidden assumption is to say that Einstein assumed that all observers had access to the same reality. Whereas in Many Worlds (the popular name Everett’s interpretation eventually acquired), observers can become isolated from each other and end up essentially each having their own separate reality. This is still a kind of realism, although one might argue that it’s not quite as “objective” as the original scientific realism Einstein had in mind. In Many Worlds, there isn’t a single reality within which everyone participates, but instead multiple realities. Everett called his interpretation the “Relative State” formulation to emphasize the relativism involved in it, although today it has become more commonly known as Many Worlds.
Although Many Worlds understandably sounds too bizarre for many people, and very different from Copenhagen, the truth is they are much more similar to each other than most people realize. Conversely, both are very different from Hidden Variables and Objective Collapse — as the latter 2 represent both different physics and different mathematics, not just a different linguistic framework for discussing the math. Whether one prefers Many Worlds or Copenhagen may simply be a matter of taste as far as what the right words are to use. Whereas whether one believes that quantum mechanics as it stands is incomplete and needs to be completed or modified is a more substantial disagreement which carries with it significantly different predictions for future experiments.
A large portion of my book will be about the different interpretations of quantum mechanics, and how the same physics can be described in many different semantic frameworks even when the same mathematics and physics are assumed. I believe it is because of this that there has been more confusion in media and popular coverage of quantum mechanics than in any other branch of physics. But the focus in future chapters will be more about expanding knowledge than about correcting false popular narratives.