Caribbean Stories

The Day Time Machines Went Kaput


8. Quantum Reality

THE STRIKING GREEN T-SHIRTED EMCEE returned to his perch at the lectern to bid auf Wiedersehen to the departing speaker about to step down at the opposite end of the stage, who smiled as he waved at the cheering audience. “We all thank Professor Stauffenberg for his wonderful talk on the principal post-Newtonian, classical approaches to time,” said Martinelli. Stauffenberg gave him a thumbs-up with a grin. Martinelli was perhaps overly generous, for it was he who’d discussed time as conceived of in special relativity; Stauffenberg simply referred to it. Most gracious host. But Martinelli chooses his words carefully when talking hardcore physics. He is methodically precise. In his courses, there is no way for the student to get lost in the discussion owing to ambiguities in Martinelli’s explanations. One always knows exactly where one stands in relation to the material being presented. There may be questions about the contents of the presentation, of course; that is normal when discussing new ideas. But one is never confused about, or becomes disoriented in, the playing field itself. Martinelli makes sure that all the bases are properly covered when he develops his presentation. Science instills intellectual rigor. Accuracy is paramount. Arguments must be coherent. Balonium is out. And veracity is mandatory. If you can’t stand the heat, go major in something else.
    Unfortunately, every now and then some blasted Homo bastardus breaches the ivory bastion. Avast, ye reprobates! Bastardus, begone to thy sty!
    “Let me explain what I mean by ‘post-Newtonian classical approaches to time’.” See? Just the thing for a mostly lay audience. “In the beginning Newton declared that time, ‘Absolute, true, and mathematical time, of itself, and from its own nature, flows equably without relation to anything external’*. In other words, time marched to its own beat at every point in the universe in identically dispensed measures, irrespective of anything, this meaning change of any kind whatsoever, period. He was adamant about the irrelevance of change: ‘All motions may be accelerated and retarded, but the flowing of absolute time is not liable to any change.’ In effect, the universe had a master clock that kept the passage of time uniform everywhere always, and that was it. But… where was this clock? Forget it, think Platonically. But why was this so? Because Newton said so. Newton later stated that he made no hypotheses. He only made laws, one would think he came to believe.”
    Sir Isaac was some character, undeniably. To put it mildly.
    “At least he acted as if he did. His critics, however, had other ideas about the nature of time. Both Plato and Aristotle linked time to change —specifically, to motion— and this notion held sway with many of Newton’s contemporaries. With the rise of thermodynamics, the connection between the arrow or direction of time and physical change, in the form of molecular motion, took hold through entropy. So the flow of time was indeed susceptible to change. Einstein finally put to rest the Newtonian conception of absolute time with his theory of special relativity, where motion near the speed of light wreaks havoc with our intuition about time. Time suddenly became just as pliable as taffy, as it were, because of motion.”
    Just as gooey, technically. Not as tasty, though.
    “Now, relativity theory is commonly thought of as being modern physics, since upon being forged in the twentieth century it electrified the world. But in the physics community it is typically considered classical, along with everything else in the discipline up until then. With one significant exception: quantum mechanics, which had begun to sprout a few years before special relativity but still had quite a ways to go before attaining completeness, if indeed it ever has. Even as Einstein dabbled in relativity, a number of simply outstanding physicists were constructing Physics 2.0, the brave new world of modern physics, beginning with Max Planck and —Ta-da!— Albert Einstein himself. Relativity theory does not incorporate quantum mechanics and as such was left out in the cold of classical physics. For the world would never be the same once physics encountered the quantum.”
    The Godzilla of natural sciences.
    “Yes, quantum: the discretization of energy. To discretize means to arrange into separate and distinct units. In mathematics, discrete is the categorical opposite of continuous. Energy, Planck discovered and Einstein later validated theoretically, comes in discrete allotments, which Einstein called quanta: minute packets that are loosely analogous to atoms in matter. Before Planck, energy was thought to be continuous, that is, infinitely divisible. Not so. It comes in chunks or bundles, as Planck called them. The world, it turns out, is fundamentally granular, in energy as well as matter. It’s made up of tiny bits of stuff that are powered by tiny specks of energy. The world is basically a big Erector set with which you can construct just about anything, especially dynamic systems: stars, supernovae, heavier elements, planets, DNA, ecosystems, people; that sort of thing. Keep in mind that matter and energy are mutually convertible, as shown by Einstein, which makes Big Erector wondrously versatile. Here we see a basic symmetry of nature: its building blocks, matter and energy, are cleverly unitized. Nature is not analog but digital, quotidian appearances notwithstanding. And digital is more practical than analog, we have learned. Interestingly, energy was discovered to be quantized before atoms were finally proved to exist. And yes, it was Einstein who demonstrated that atoms were physically real.”
    Einstein was a brilliant physicist shrewdly disguised as a patent clerk. At the time he was just twenty-six! Alas, he failed to come up with Erector and Meccano sets. You would think that an alert patent clerk would have a leg up on toy makers. That’s what you get for musing on abstract theories.
    “Discretization is actually the least knotty aspect of quantum physics. Far stranger things awaited. In order to give you a gentle introduction to this complex subject, we’re going to stream a video that we think you will enjoy. It’s an episode of the adventures of Dr Quantum, the animated cartoon persona of Fred Alan Wolf, the celebrated theoretical physicist. Dr Quantum discusses the famous double-slit experiment, the best introduction there is to the enigma of quantum mechanics.
    “Let me see if I can get this thing to work… Alright, here we go!”

    “Let’s give Dr Wolf a hearty applause for the finest explanation on the Web of what quantum mechanics is all about. Danke schön, Professor Volf.”
    Wolf is as American as apple pie, but vat zee hek.
    “Now, let’s recap the findings of the double-slit experiment. First, quantum effects become manifest at the atomic and subatomic level. We saw this when Dr Quantum said ‘Now, let’s go quantum’ and the experimental apparatus shrank out of sight. The reality we observe at our macroscopic level does not normally exhibit quantum effects, although it certainly would if the right conditions were present. After all, physical reality at all scales must incorporate, actually, must conform to the underlying basis of quantum reality. The ‘right conditions’ are pretty technical, so we’ll skip them for now. But they are extremely important. They are what make our macroscopic time machine possible.”
    Covering the ‘right conditions’ takes an advanced, full-year physics course. And you’re barely scratching the surface. I took mine with Martinelli. Spectacular. Challenging. A rite of passage. It’s what makes you a physicist nowadays.
    “Second, at the microscopic level, things sometimes behave as particles and at other times like waves. Not just electrons and photons, but everything. What we find depends on how we carry out our observation, on the nature of the measuring apparatus. If the measurement is such that it detects moving particles, we observe the particle aspect of the entity, obviously. But if it detects waves, as revealed by, say, an interference pattern, the aspect that we observe are either matter waves or energy waves. Light, for example, has an electromagnetic energy wave aspect and a particle aspect, its quantum being the photon. The electron has a matter wave aspect along with its familiar particle. In any one observation, we will detect one aspect or the other but not both. Contrary to what our macroscopic experience has led us to believe, both aspects, particle and wave, are inherent to everything that exists, whether matter or energy. Here we see yet another symmetry of nature. This twofold feature is not a sundering dichotomy but a unified, complementary duality. Things simply have a dual nature in reality.”
    Duality is a fundamental concept largely ignored in Western thinking. We tend to see things from a single perspective, often one which we believe is most expedient or that confirms our preconceived mindset, rejecting out of hand a more realistic appraisal of the overall situation. This culturally ingrained dogmatism, by inducing shortsightedness, can at critical junctures be downright dangerous.
    “All objects, objects being collections of particles, have a wave component, even you and I. So why can’t we see our wave-selves in the mirror?”
    Please, I have enough problems with my particle self as it is.
    “Because of the short wavelengths associated with macroscopic objects. The wavelength of the matter wave gets immeasurably shorter as the momentum of the object increases. Momentum is the object’s mass times its velocity. It measures the motion of the object. Large momenta render the wave aspect so vanishingly small that it cannot possibly be detected. But it’s there.”
    And you thought you knew your self all along. Think again.
    “Third, when investigating quantum phenomena, the observer is part of the measuring apparatus. This is one of the most perplexing conclusions to be drawn from quantum physics. In the double-slit experiment, if the observer does not try to ascertain through which slit the electron passes, the electron behaves as a wave. But if an attempt is made to determine the electron’s trajectory through the slits, the electron collapses to a particle. That is incredible. It is as if the physical nature of the electron transforms abruptly when human observation is brought to bear on the experiment. There is no comparable situation to this in macroscopic classical physics. Macro objects never vanish into waves when one stops looking at them. Or so we think. No one has been able to provide a sensible explanation for the role played by human observation. It remains a quantum mystery.”
    George Berkeley, the eighteenth century British empiricist, even though he was Irish and an idealist —go figure— being a resolute immaterialist, would have seen no mystery at all. Maybe his immaterialism was idealistically empirical.
    “The final point I wish to bring up was not discussed in the video, but it follows from the third point I just mentioned. Let’s suppose we move the detection device (the blinking eye in the video) past the double-slit screen but still ahead of the recording screen. In other words, the device is placed between the screens. Initially the device is off. When we shoot electrons from the electron gun they should traverse the double-slit screen as matter waves because they are not being observed. If the detection device remains off, an interference pattern will build up on the recording screen, as expected. But if the detection device is switched on, randomly, after an electron passes the double-slit screen, presumably as a wave, the pattern that will now form on the recording screen is no longer that of wave interference but of particles!”
    Stranger things shall you see. Stick around.
    “But how could that be? To the best of our knowledge, to form a particle pattern, the electron had to pass the double-slit screen as a particle through only one slit. But since it was not being observed, previous experiments indicate, or so we have interpreted, that it passes through both slits as a wave. The wave had already gone through the slits before the detection device ‘observed’ the electron. Consequently, the pattern forming on the recording screen should have been that of wave interference because the matter wave had already diffracted when it went through the slits. In order to generate a particle pattern on the recording screen, it would seem that the electron went back in time, thus erasing the wave diffraction it had just undergone, and traversed the slits screen once again, except this time through only one slit as a particle. How could this possibly be? How could the electron travel backward in time?”
    That is standard physical reality, the genuine article. What you get out there in the macro world is a woefully inferior substitute, purely contingent. Dull, too.
    “We see here that quantum mechanics opens the door to time travel to the past. That is not the only possible interpretation of the delayed choice experiment, as its designer, John Archibald Wheeler, named it. Wheeler asserted that quantum phenomena are neither waves nor particles until measured: ‘No phenomenon is a phenomenon until it is an observed phenomenon.’** Time travel is not needed in this interpretation, although one must then ask, ‘Okay, so what is it that exists as a momentary unobserved non-phenomenon?’ Nonetheless, there are other quantum mechanical curiosities that also suggest time travel. And Professor Esch, our next speaker, intuited that the time-travel interpretation was the right one to pursue.”

Posted:   10 Apr 2015
Revised:   1 May 2015

Stuff from the Web

Alain Aspect speaks on John Wheeler's Delayed Choice Experiment •8:48

Alain Aspect • Breaking the Wall of Quantum Weirdness •15:33

Image credits:

"Doubleslit". Original work by Loo Kang Lawrence Wee, a physics teacher and educational technology specialist in Singapore. See his blog. Animated image licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license via Wikimedia Commons, 16 October 2013.

"QM Template". Original work by Maschen. Dedicated to the public domain under the Creative Commons CC0 1.0 Universal Public Domain Dedication via Wikimedia Commons, 4 January 2013. Maschen's artwork is quintessentially emblematic of quantum mechanics. Proof of claim left as an exercise for the reader.


Video credit:

"Dr Quantum and the Double-Slit Experiment" by Fred Alan Wolf, a short episode from the DVD, "What the Bleep? Down the Rabbit Hole", episode which is widely available on the Web. Included here under the Fair Use doctrine for nonprofit educational purposes, such as those of this website. There is an open source version of the video ("free for use in any educational setting") without the Dr Quantum character, titled "Double Slit", produced by the Cassiopeia Project and freely available for download on their site as well as elsewhere on the Web. However, I feel it is much more appropriate to make use of Dr Wolf's video, on which the open source version is based, in recognition of his original educational contribution.


Quotations:

* Newton's quotations come from his Scholium to the Definitions in Philosophiae Naturalis Principia Mathematica, Book 1 (1689); translated by Andrew Motte (1729), revised by Florian Cajori, Berkeley: University of California Press, 1934, pp 6-12, sections I and V; posted as "Newton's Scholium on Time, Space, Place and Motion" at the Stanford Encyclopedia of Philosophy.

** Wheeler's quotation appears in "The 'Past' and the 'Delayed-Choice' Double-Slit Experiment" in Mathematical Foundations of Quantum Theory, A.R. Marlow, ed., Academic Press, 1978, p 14. Expanding on the theme, John Horgan writes: "Actually, Wheeler says, quantum phenomena are neither waves nor particles but are intrinsically undefined until the moment they are measured. In a sense, the British philosopher Bishop Berkeley was right when he asserted two centuries ago that 'to be is to be perceived.'" See Horgan, "Quantum Philosophy" in Scientific American, July 1992, p 97.

Plato's views on time are discussed in Timaeus 37c-38b. Aristotle presents his arguments in Physics IV 10-14.


Further reading:

Double-Slit Experiment - Wikipedia

Young's Double-Slit Experiment - Simple English Wikipedia

History of Quantum Mechanics - Wikipedia

Introduction to Quantum Mechanics - Wikipedia

Wheeler's Delayed Choice Experiment - Wikipedia