3.3. Does quantum mechanics contradict Special Relativity?
Another empirical challenge to Special Relativity arises from the collapse of the wavefunction in quantum mechanics. This collapse, a key feature of the Copenhagen interpretation, is considered to be instantaneous or at least many times the speed of light, apparently contradicting SR’s assumption that the speed of light is a cosmic speed limit. As we’ll see below, however, this conflict interpretation is hotly debated. Salart, et al. 2008 found that quantum collapse occurs at least 10,000 times the speed of light. Carroll 2010 states (p. 231):
The arrow of time is … a fundamental puzzle, and it’s possible that quantum mechanics will play a crucial role in resolving that puzzle. And there’s something else of more direct interest: That process of measurement, where all of the interpretational tangles of quantum mechanics are to be found, has the remarkable property that it is irreversible . Alone among all of the well-accepted laws of physics, quantum measurement is a process that defines an arrow of time: Once you do it, you can’t undo it. And that’s a mystery.
How does this quantum effect mesh with SR? One method for reconciling these two pillars of modern physics is to suggest that quantum collapse takes place outside of space and time and is thus not physical (or is physical in some other manner) (see , e.g., Brooks 2014 or Walleczek and Grössing 2016). This interpretation presents some problems in terms of parsimony, particularly if we can offer a different interpretation that allows for all of physical reality to coexist in the same set of dimensions, the same reality. Lorentzian relativity, which I’ll label LR from now forward, suffers the same issue as SR in this context because it also includes the speed of light as an asymptotic speed limit (because it also uses the Lorentz transformations). Some versions of neo-Lorentzian relativity, however, don’t suffer from this issue because there is no necessary speed limit of causal effects in some neo-Lorentzian approaches. As such, quantum effects are simply very fast effects that present no particular interpretational challenge for these neo-Lorentzian approaches.
Callender 2007 examines in detail whether wavefunction collapse necessarily violates SR, and concludes that it does under both the standard Copenhagen interpretation and in hidden-variable interpretations, but there is no conflict for all other interpretations of quantum mechanics: “With all these qualifications now in place, we can only say that [philosopher of science] Popper’s conclusion [that wavefunction collapse necessarily weighs in favor of Lorentz’s interpretation] threatens most if one adopts a standard collapse or hidden variable interpretation of quantum mechanics as well as a standard reading of Lorentz invariance.” (Callender goes on, nevertheless, to present a vigorous defense of tenseless time in physics, which is beyond the scope of the present paper to address.)
Walleczek and Grössing 2016 suggests a new approach that would reconcile apparently superluminal quantum collapse, including in hidden variable approaches like the de Broglie-Bohm interpretation, and relativity theory by proposing an “effective non-signalling” constraint that allows for superluminal influences but not superluminal signaling or communication. They state the problem clearly: “The present work offers a communication-theoretic analysis of the conceptual impasse that exists between (1) the possibility of superluminal influences and (2) the impossibility of superluminal signalling as required by special relativity: Does the presence of superluminal influences necessarily imply superluminal signalling and communication?” The authors propose that “Shannon signals,” that is, physical signaling or communication between “epistemic entities,” do not occur with quantum collapse, but “non-Shannon signals,” which involve physical influences but not signaling or communication between epistemic entities, are permissible. This distinction, the authors suggest, saves quantum effects from being “not physical” and thus offers a path toward reconciling SR and nonlocality.
My view is that this distinction between influences and signaling between epistemic entities is strained because it rests on an assumption that a certain set of physical limits applies to epistemic agents but don’t apply to the rest of the universe. Why would nature operate in this radically emergent binary manner when all the evidence of biology suggests that the evolution of life and consciousness occurs in steady incremental fashion? Based on this objection, I find Walleczek and Grössing’s attempt to save SR from falsification due to conflicts with non-locality to be problematic.
As we’ll see in the discussion below about J. S. Bell’s work on quantum theory vis a vis SR, there are two primary choices in approaching this apparent conflict between quantum nonlocality and SR: 1) look for a way, as Walleczek and Grössing have attempted, to make a reasonable distinction between superluminal influences and superluminal signaling/communication, in order to save SR from this apparent falsification; or 2) accept that superluminal signaling/communication is indeed occurring and that this is further evidence that SR should be considered falsified. The second option allows for de Broglie-Bohm quantum theory to stand, as does the first option.
The second option is anathema to the large majority of physicists and philosophers today who have long accepted SR as a powerful and foundational theory of modern physics. For example, Walleczek and Grössing 2016 assumes that any interpretation that violates SR is “physically unrealistic”: “As a consequence, relativity theory would be violated which would render an ontological quantum theory, like de Broglie–Bohm theory, physically unrealistic.” But given the weight of evidence that challenges SR, plus the other benefits of alternative interpretations of the Lorentz transformations considered further below, we shouldn’t shy from considering option 2, which is indeed more physically realistic than option 1.
In conclusion, wavefunction collapse, whether instantaneous or simply faster than the speed of light, seems to present another significant challenge to SR.
4. Octupole deformation in barium nuclei challenges time symmetry
A more recent line of evidence also weighing against SR is the 2016 finding that there is an orientation to the octupole deformation in barium nuclei. Bucher, et al. 2016 concludes that “despite significant uncertainties on the measurement, the data also indicate an octupole strength larger than calculated in various theoretical approaches.” In describing this work for the public, Scheck, one of the authors of the new study, stated: “We’ve found these nuclei literally point towards a direction in space. This relates to a direction in time, proving there’s a well-defined direction in time and we will always travel from past to present.”
While the new paper and the researchers both avoid discussing whether there is a conflict with SR, this implication mentioned by Scheck seems obvious. If further research supports this recent finding, which, as the paper describes, does currently include large measurement uncertainties, it will pose another serious empirical challenge to SR and provide further support for a Lorentzian or neo-Lorentzian approach instead.
5. Changing views about alternatives to SR
Now that we have reviewed the main empirical challenges to SR, let’s review some of the historical theoretical discussions surrounding SR and alternatives. J. S. Bell, the colorful Irish physicist who formulated the Bell inequalities, which formed the theoretical basis for Aspect’s non-locality experiments, was a supporter of the Lorentzian view. He stated in a 1986 interview with physicist Paul Davies (Davies 1986):
[T]he pre-Einstein position of Lorentz and Poincaré, Larmor and Fitzgerald was perfectly coherent, and is not inconsistent with relativity theory. The idea that there is an aether … is a perfectly coherent point of view. The reason I want to go back to the idea of an aether here is because … the suggestion that [in nonlocality experiments] behind the scenes something is going faster than light. Now if all Lorentz frames are equivalent, that also means that things can go backward in time … [This] introduces great problems, paradoxes of causality, and so on. And so it is precisely to avoid these that I want to say there is a real causal sequence which is defined in the aether.
Yuri Balashov, a philosopher at the University of Georgia, stated in Balashov 2000:
[T]he idea of restoring absolute simultaneity [which is the basis for the Lorentzian interpretation of relativity theory] no longer has a distinctively pseudo-scientific flavor it has had until very recently. It is a well-known fact that one could accept all the empirical consequences of SR (including length contraction, time dilation, and so on) and yet insist that there is a privileged inertial reference frame, in which meter sticks really have the length they have and time intervals between events refer to the real time.
Hawking, in discussing Einstein’s development of our modern theory of gravity, general relativity, states: “[Einstein’s] theory of general relativity further complicates this matter by proposing that gravity gives rise to the structure of space itself. To put this plainly, gravity is defined even in ‘empty’ space, and thus, there must be something” even in empty space. He adds: “That ‘something’ is the ether, or, in modern language, a field… In many respects, this is one of the most important contributions of relativity to physics. In the modern view, all forces arise from fields. In quantum theory… the particles themselves arise from the field.”
In a little-known tale of 20th Century physics, Einstein himself regretted his 1905 dismissal of the ether as “superfluous,” in his seminal paper. Einstein’s own thinking evolved to the point that he realized that some type of (relativistic) ether was theoretically necessary after all. Einstein called this the “new ether,” but changed his terminology over time, as we shall see below [Footnote 1].
[Footnote 1. For a thorough discussion of Einstein’s ideas on the ether, based on primary documents in German, with English translations, see Einstein and the Ether (2000) by Ludwik Kostro.]
In 1915, Einstein published his general theory of relativity, which asserted a very different conception of space and time than that put forth in 1905. In general relativity, space has no independent existence; rather, it is a consequence of the various fields that are ontologically fundamental. Shortly after his momentous general relativity paper was published, he exchanged letters with Lorentz. Lorentz argued throughout his career that some notion of the ether was necessary for a valid description of reality. Einstein conceded eventually that indeed a non-material but still physical ether was necessary to explain inertia and acceleration. Einstein first described his “new ether” in a 1916 letter to Lorentz:
I agree with you that the general theory of relativity is closer to the ether hypothesis than the special theory. This new ether theory, however, would not violate the principle of relativity, because the state of this … ether would not be that of a rigid body in an independent state of motion, but every state of motion would be a function of position determined by material processes.
Einstein also wrote in a 1919 letter to Lorentz:
It would have been more correct if I had limited myself, in my earlier publications, to emphasizing only the non-existence of an ether velocity, instead of arguing the total non-existence of the ether, for I can see that with the word ether we say nothing else than that space has to be viewed as a carrier of physical qualities.
From 1916 to 1918, Einstein was in the thick of discussions with a number of colleagues about the nature of space and the ether, with respect to general relativity. As Walter Isaacson recounts in his biography of Einstein (Isaacson 2008), Einstein’s thinking changed dramatically during this period. In 1918, he published a response to critics of special and general relativity. In this dialogue, Einstein writes that the “diseased man” of physics, the “aether,” is in fact alive and well, but that it is a relativistic ether in that no motion may be ascribed to it.
In 1920, Einstein became more emphatic regarding the ether, recognizing explicitly that the ether was a necessary medium by which acceleration and rotation may be judged, independently of any particular frame of reference:
To deny ether is ultimately to assume that empty space has no physical qualities whatever. The fundamental facts of mechanics do not harmonize with this view… Besides observable objects, another thing, which is not perceptible, must be looked upon as real, to enable acceleration or rotation to be looked upon as something real … The conception of the ether has again acquired an intelligible content, although this content differs widely from that of the ether of the mechanical wave theory of light … According to the general theory of relativity, space is endowed with physical qualities; in this sense, there exists an ether. Space without ether is unthinkable; for in such space there not only would be no propagation of light, but also no possibility of existence for standards of space and time (measuring- rods and clocks), nor therefore any spacetime intervals in the physical sense.
Again, Einstein stressed that this new ether was relativistic. Einstein struggled with these ideas for much of his career. As a realist, Einstein argued during the middle and latter parts of his career that physics must attempt to describe what is truly real and not avoid discussion of concepts that cannot be directly detected – such as the ether – even if they seem to be logically necessary due to indirect evidence. So for Einstein, even though the ether was considered undetectable, he deduced its existence because of its effects on observable matter through inertia, acceleration and rotation. In this manner, then, the new ether was detectable.
In sum, while Einstein viewed his new ether as relativistic, it is an important step in reinterpreting the Lorentz transformations to recognize that even Einstein, who dismissed the ether as “superfluous” in his 1905 paper on special relativity, brought this concept back into his physics with general relativity and his later work. LR relies on physical interaction with a physical ether as the mechanism for relativistic effects. This ether can be viewed simply as space itself, but not space as a true void because the space of modern physics has defined qualities. As Hawking states above: space is not truly empty. This Lorentzian ether is not relativistic in the sense that Einstein suggested because it does not abide by the special principle of relativity. Rather, it is the background frame that Einstein sought to dispel by making his special principle of relativity one of his axioms in his 1905 paper.
6. Is the Higgs field a new ether?
Frank Wilczek, a Nobel Prize-winning physicist at MIT, writes in his 2008 book The Lightness of Being: Mass, Ether and the Unification of Forces :
No presently known form of matter has the right properties [to play the role of the ether]. So we don’t really know what this new material ether is. We know its name: the Higgs condensate [or Higgs field], after Peter Higgs, a Scots physicist who pioneered some of these ideas. The simplest possibility … is that it’s made from one new particle, the so-called Higgs particle. But the [ether] could be a mixture of several materials. … [T]here are good reasons to suspect that a whole new world of particles is ripe for discovery, and that several of them chip in to the cosmic superconductor, a.k.a the Higgs condensate.
As the title of Wilczek’s book suggests: he argues from many lines of evidence that there is in fact an ether that undergirds space, which he calls alternately the ether, the Grid or the “cosmic superconductor.”
Lawrence Krauss, a well-known physicist and science popularizer, wrote of the Higgs field announcements in 2012 in a way that supports a revival of the ether concept (Krauss 2012):
The brash notion predicts an invisible field (the Higgs field) that permeates all of space and suggests that the properties of matter, and the forces that govern our existence, derive from their interaction with what otherwise seems like empty space. Had the magnitude or nature of the Higgs field been different, the properties of the universe would have been different, and we wouldn’t be here to wonder why. Moreover, a Higgs field validates the notion that seemingly empty space may contain the seeds of our existence.
As such, the evidence regarding the Higgs field, or some similar field and particle if it is ultimately determined that the 2013 evidence was not the Higgs itself, may lend support to the ether concept and, more generally, to the idea that there is a total field that undergirds our reality; the “seeds of our existence,” as Krauss states.
7. Some theories of quantum gravity suggest violations of SR
An additional non-empirical argument merits mention here. A number of approaches to quantum gravity – a theory that would reconcile general relativity with quantum mechanics – suggest violations of SR. These are purely theoretical considerations at this point, since none of these theories has been tested at this juncture in a manner that would support or deny the suggested violations of SR. Botermann et al. 2014 states: “Interest in [Lorentz Invariance] tests have been further boosted by the search for a theory reconciling quantum theory with general relativity, as many attempts for such a quantum gravity explicitly allow Lorentz violation, making it a potential discriminatory experimental signature for the underlying theory.”
Lorentz Invariance refers, of course, to violations of the principle of special relativity that is at the heart of Einstein’s SR. This terminology is admittedly confusing, but it arises from the fact that Einstein’s 1905 SR paper adopted the Lorentz transformations, as we’ve discussed above. So SR uses the Lorentz transformations but explicitly rejects the Lorentzian interpretation of those transformations in favor of the spacetime approach that Einstein championed.
8. Is special relativity more parsimonious than Lorentzian relativity?
Knowledgeable physicists will acknowledge that LR is a viable approach given that both use the Lorentz transformations and are thus generally not considered to be empirically distinguishable. This dilemma about which theory is better is sometimes described as an “aesthetic” debate, not because the difference in interpretations is trivial but because without empirical data to make a choice we must look to other considerations like aesthetics and parsimony. As discussed above, however, there is indeed a substantial amount of data that can empirically distinguish these two interpretations – but this state of affairs is not widely acknowledged yet.
Physicists who argue in favor of Einstein on this issue (the large majority still would today) rest their arguments often on the notion that Special Relativity is more parsimonious because it can explain the same phenomena with fewer components; namely the absence of an ether.
A related parsimony argument centers on our assumptions about the speed of light. Einstein assumed that the speed of light was constant no matter the speed of the observer, as an explanation of the Michelson-Morley data. We can assume otherwise, however, particularly considering that no other speeds in the universe behave this way. That is, all other speeds do in fact change based on the speed of the observer.
In the context of measuring the speed of light, Einstein’s assumption leads to an ε value of 0.5 in the following light speed measurement equation first formulated by Reichenbach 1924:
t2 = t1 + ε(t3 − t1)                                                                                                                            (1)
ε of 0.5 is a prima facie parsimonious assumption, despite it being highly counterintuitive, because it allows for an easier measurement of the speed of light by using mirrors to reflect light back to the source (see Jammer 2006 for more, particularly the last chapter). Operationally, this allows an experimenter to shoot a ray of light, at t1, at a mirror, reached at t2, and measure the time elapsed for the light’s return at t3. By dividing the elapsed time by two, we can derive the average speed of light over this distance. This technique only works for determining the one-way speed of light if one assumes that the speed out is the same as the speed back, which equates to an ε of 0.5. But, again, any other speeding object would not have the same speed in both directions because of other forces impacting the object differently based on its direction, such as air speed. And if the observer was herself moving during this experiment, any other moving object would indeed show a different speed out and back.
Einstein’s assumed isotropic speed of light made sense at the time operationally, but we now know that many problems arise from this assumption, including how to reconcile the obvious flow of time in quantum mechanics, in the cosmic frame, and in everyday experience with this assumption. Reichenbach stated: “If the special theory of relativity prefers the first definition, i.e., sets ε equal to 1/2, it does so on the ground that this definition leads to simpler relations.”
We are then left with an ostensibly simplifying assumption that leads ultimately to a more complex and sometimes self-contradictory and empirically-challenged system than other alternative assumptions, including the more intuitive notion that the speed of light does in fact change based on the speed of the observer.
In order to explain various phenomena, it is in my view more parsimonious to adopt the LR version of relativity and an ε different than ½. This approach accords with the various lines of evidence discussed above (CMB frame of reference, large-scale non-homogeneity, quantum collapse, octupole deformation, etc.), as well as the passage of time. Under this approach, the specific value of ε depends on the speed of the frame through the ether.
Maudlin 2012 describes an approach to SR that doesn’t rely on the Lorentz transformations, relying instead on basic assumptions about the nature of space and light:
When we first introduced the notion of a Lorentz coordinate system, it was completely unconnected with any physical procedures: the coordinates were used only as an abstract way to specify the intrinsic geometry of Minkowski space-time. Next, we connected that geometry to the behavior of matter by a set of physical principles: the Law of Light, the Relativistic Law of Inertia, and the Clock Hypothesis. Finally, we have shown that if these principles are accepted, then a certain physical procedure, employing inertially moving ideal clocks and light rays in a vacuum, will result in the assignment of Lorentz coordinates to Minkowski space-time. At no point in this procedure have we so much as mentioned the “speed of light,” or postulated that the “speed of light is constant”: Minkowski space-time does not support any objective measure of the speed of anything. Nor have we anywhere invoked the notion of an “inertial coordinate system” or postulated that “all inertial systems are equivalent” or that “the laws of physics take the same form in all inertial systems.” Rather, we have postulated a certain geometrical structure to space-time, invested that structure with physical significance for the behavior of visible matter by means of some physical postulates, and then described how to use the matter to construct coordinate systems.
As Maudlin states, however, the approach he employs relies on a set of assumptions, including the “Law of Light,” which Maudlin 2012 defines as follows: “The Law of Light can only be formulated in a space-time that associates a light-cone with each event. Note that the Law of Light mentions nothing about the source of the light save that the source emits at a particular event. So the Law of Light implies the phenomenon cited above: two light rays emitted from the same point in a vacuum will arrive together at a distant observer.” That is, the Law of Light from the outset requires that light behave differently than all other physical phenomena we know of because its velocity is postulated to be independent of the speed of the emitting source.
Accordingly, Maudlin’s Law of Light is very similar to Einstein’s light speed postulate in Einstein 1905, which states “that light is always propagated in empty space with a definite velocity c which is independent of the state of motion of the emitting body.” The difference, as Maudlin highlights, is that the Law of Light postulates nothing about the velocity of light. But as Maudlin 2012 also acknowledges [Footnote 2], the velocity of light may be measured in relation to any chosen frame of reference and it will be the same velocity in all cases, based on the fact that the postulate would not allow any other finding.
We are, then, even under Maudlin’s alternative approach to SR, back to the issue of postulating either the isotropic/absolute speed of light or the existence of an absolute space/ether, which is the same dichotomy distinguishing SR and LR.
[Footnote 2. Maudlin 2012 states: “Light, in itself, has no speed, since there is no absolute time or absolute space in Relativity. But relative to a coordinate system, we can assign a light ray a coordinate speed.” This is, of course, the case for any speed because speed is only ever knowable in relation to other things.]
9. Some advantages of adopting a Lorentzian or neo-Lorentzian notion of relativity
Callender 2007 and Janssen 2002 tread some of the same ground covered in the present paper. Janssen 2002 argues that SR is still the superior interpretation when compared to alternatives. However, Callender 2007 agrees that the Lorentzian interpretation is warranted and probably a superior interpretation to SR in some ways [Footnote 3], but he disagrees that Lorentzian relativity rescues tensed time (the passage of time), due largely to the “coordination problem” between a psychologically preferred frame and the preferred frame in physics. I won’t address the coordination problem in this paper but Zimmerman 2011 does.
[Footnote 3. “[Lorentzian Relativity] shouldn’t be viewed as a desperate attempt to save absolute simultaneity in the face of the phenomena, but it should rather be viewed as a natural extension of the well-known Lorentz invariance of the free Maxwell equations. The reason why some tensers [thinkers who view the passage of time as an objectively real phenomenon] have sought all manner of strange replacements for special relativity when this comparatively elegant theory [Lorentzian Relativity] exists is baffling.”]
Despite Callender’s vigorous argumentation against tensed time—the objectively real passage of time—it is not clear why those who prefer a tensed notion of time can’t simply posit that the preferred frame of physics is the preferred frame universally, even if we couldn’t know what that frame is. We do in fact have a strong candidate already for the preferred frame, as discussed above: the CMB plus very large-scale structures like the Great Wall and the Axis of Evil.
This approach – preferring a Lorentzian or neo-Lorentzian interpretation – renders the universe ontologically not relativistic in the sense of SR, but still allows us to use the Lorentz transformations to translate between different frames of reference. This ability to translate between frames of reference was the original intent behind Poincare’s, Lorentz’s, Fitzgerald’s and Einstein’s work on relativity theory. This approach, as discussed above, renders length contraction a result of interaction between matter and the preferred frame (ether or the total field or whatever term we prefer) and renders time dilation a coordinate effect only.
Very few discussions of SR explain the physical basis for the relativistic effects of length contraction and time dilation. Callender 2007 explicitly states that it is the “spacetime structure” that causes these phenomena, and suggests that this is a more parsimonious explanation than LR offers, with its ether friction suggestion. However, the spacetime structure that Callender alludes to is not a physical mechanism; rather, it reduces to the assumption of the relativity of simultaneity that was the key step in Einstein’s original 1905 paper on SR.
That is, by assuming the relativity of simultaneity, which results in a particular measurement convention for the speed of light, length contraction and time dilation necessarily result from the Lorentz transformations. But there is no physical mechanism proposed for these phenomena in SR. Why do objects contract the more they approach the speed of light? All SR can say is “because we assume, for operational simplicity, the relativity of simultaneity, which results in an intermingling of space and time into a single spacetime.”
But we can simply change the assumption from the relativity of simultaneity to absolute simultaneity and the mathematical results of the Lorentz transformations and their empirical successes don’t change. Instead, if we adopt Lorentz’s explanation of these phenomena we gain a physical mechanism for length contraction, which is caused in LR by interaction with space itself, which we know now is not actually empty. So it is not “spacetime structure” in LR that leads to length contraction but “space structure,” akin to a drag or friction effect that increases as an object’s speed relative to space increases. This is a more satisfying physical mechanism because it is natural that if space is not truly empty that there would indeed be some kind of drag effect analogous to friction. We may describe it as “space friction” or “ether friction.”
Time dilation in LR is reduced to a coordinate effect akin to changing time zones. There is no physical or real temporal change in changing frames of reference. Rather, there is only a change in convention in terms of how we measure time and translate between different frames of reference. This approach to time dilation resolves all manner of time paradoxes like the Twins Paradox, in a very elegant way: there is no paradox in LR because there is no differential aging of the separated twins, just different conventions for telling time for the separated twins.
But perhaps the larger benefit of LR is reconciling our fundamental experience of the passage of time, and the overwhelming evidence of the passage of time in the natural world, with a key theory of modern physics. Earlier in my essay I discussed Bardon’s challenge: “This is the core challenge in the contemporary philosophy of time: how to reconcile the seeming ineliminability of the experience of the passage of time (manifest time) with the cold, hard conclusions of logic and physics (scientific time).” Because LR doesn’t result in physical time dilation there is a real passage of time and an absolute simultaneity in the universe (even if we can’t know in practice what events are truly simultaneous with each other). “Scientific time” and “manifest time” become one and the same under this approach.
A real passage of time and a real order of events—the A-series approach to time in the philosophy of time—reconciles the dramatic departure from human experience and empirical fact that has existed over the last hundred years since SR and its block universe notion of time became widely accepted. We need not sacrifice the utility of the Lorentz transformations; we should instead reinterpret their significance in a manner that is commonsensical, elegant, and empirically sound.