Furthermore, an astronomical observation completed in 1998 with the aid of the Hubble Space Telescope found that the expansion of the universe is accelerating—so a galaxy’s recession speed measured today is faster than its speed measured yesterday. This accelerated expansion is attributed (although reluctantly) to the existence of dark energy, which is hypothesized to permeate the universe and act as a kind of antigravity by stretching space and causing it to expand at continuously faster speeds. Dark energy, which has not yet been detected, is one of the most puzzling mysteries of the universe. Dark matter is yet another great puzzle: though invisible, for it does not emit light, its existence is inferred indirectly by its gravitational pull on neighboring stars. What makes dark matter invisible, no one knows. “Dark matter is attractive [it attracts stars], dark energy is repulsive [it’s hypothesized to push galaxies apart and cause the expansion of the universe].”19
Ordinary matter, matter we can see, which makes up flowers, people, planets, stars, and galaxies, is only about 5 percent of the total stuff in the universe. The other 95 percent, which includes dark energy and dark matter, is stuff that we neither see nor know much about, although their subtle presence is deduced in some way.20 Space, even “empty” space, is a place of constant, frantic activity of virtual particles, light, gravity, dark energy, dark matter, ordinary matter, of Higgs boson particles, possibly strings, and who knows what else. It is certainly not the Parmenidean Not-Being (the absolute nothing). Therefore, once more we emphasize that no scientific theory can base its beginning, its first cause/s, its axioms, on absolute nothing, on Not-Being; science must begin from something-ness, and what that might be becomes increasingly more complex. In fact, even Leucippus’s and Democritus’s nothing (their notion of void) is really not nothing, since from the point of view of modern physics “it [their void] was the carrier for geometry and kinematics, making possible the various arrangements and movements of atoms.”21
Fascinatingly these atomic arrangements and movements were imagined by Democritus to be carried out without the requirement of a force of, say, gravity, electricity, or magnetism; other than their direct collisions during which there was a physical contact, D-atoms experience no other force! D-atoms have no weight, and they produce no force of gravity.22 How can this be? How can there be a world without gravity, without forces in general?
Worlds Without Gravity
Weight or gravity (that is, the tendency of objects to fall or the property of heaviness) was not one of the primary characteristics of atoms but a property that was accounted for by Democritus ingeniously through motion, in particular rotational motion.23
Though motion is chaotic, Democritus argued, in an infinite space with infinite atoms there is always a chance that the bulk of the atoms of a certain region move collectively in a preferred direction of motion, rotational in particular, and produce a vortex. The rotational motion of such a vortex, Democritus thought, ultimately causes the bigger atoms (the more massive, the heavier, as we would say today, having gravity in mind) to move toward its center, ultimately forming the earth and the water on it, and the smaller atoms (the lighter) to move toward its outskirts, ultimately forming the air, the sky, and the stars. Because the dynamics of our world system is still rotational (e.g., the sky rotates, relative to us, and so in a sense do the moving clouds), objects made of the bigger atoms, like a rock, still fall, and objects made of the smaller atoms, like steam, smoke, or fire, still rise, Democritus argued. Air, on the other hand, generally does not fall, he thought, because of its rapid revolution, just as water does not spill from a cup when it is rapidly spun around. His analysis was logical as regards observation because the earth, which (for him) is made of the bigger atoms, formed in the center of his vortex, water, made of smaller atoms, is on earth, and air, made of even smaller atoms, is above water and earth.
Now, concerning the dynamics of a vortex, in reality it is the reverse that happens: massive objects tend toward the outskirts of a vortex, and lighter ones toward the center (this, for example, happens in a centrifuge, a device employed to separate different substances). Nonetheless, this error in Democritus’s explanation is really a minor point compared to the fact that he managed a reasonably clever explanation of the world only in terms of a basic property that atoms have, namely, their motion in the void. Thus, he saw no need of a force of a weight, of gravity, despite that apples fall as if a force is pulling them through space. The latter, legend says, inspired Newton to conceive his theory of universal gravitation for which gravity was a force, only to be abolished as a force by Einstein’s theory of general relativity. How so, and what does quantum theory say about forces in general?
Worlds Without Forces
An apple and the earth, or the sun and the earth, feel a force of attraction from each other, Newton thought, as a consequence of a mysterious action at a distance (not to be confused with the action at a distance of quantum entanglement) that he himself admitted he did not understand. How is gravity transmitted if the interacting objects do not touch each other? How does one body feel the other, how do they communicate, if nothing but empty space exists between them and if nothing specific is really exchanged by them? How does the apple know that the earth is below and that it should fall? Newtonian gravity describes rather accurately how the apple falls, but not why it falls. What’s the cause of gravity?
Space is. Einstein discovered through his theory of general relativity that space pushes the apple. More specifically, “Matter [the sun, earth, apple] tells space how to curve [recall the trampoline analogy, chapter 7] and space tells matter [and light, too] how to move,”24 said physicist John Archibald Wheeler (1911–2008), who summarized general relativity with a single sentence! Light, too, (like matter, the marble on the trampoline) zips through the curved space-time (the distorted trampoline fabric) following a geodesic (the shortest distance, which in a curved space is not a straight line), bends as it passes near massive objects like the sun, and appears to be attracted by them—a phenomenon not predicted at all by Newtonian gravity but understandably so because, unlike the trampoline fabric which is seen pushing the marble, space is not seen directly pushing matter or light; Einstein had to imagine it for us.
Hence, Einstein eliminated the need for an action-at-a-distance-type force by recognizing that the agent that transmits gravity is curved space (in fact, curved time, too, the way it passes) when distorted by matter. Space is no longer the Newtonian passive playground where events unfold but a flexible medium the geometrical shape of which changes (gets warped) by matter. The distortion of space (the changing geometry of space) in turn influences an object’s motion and feels like gravity. With such a geometrical explanation of gravity, the notion that gravity is a force is abandoned in general relativity. And in the study of the phenomena of gravity, an object’s motion through space and time may no longer be regarded as a response to an action-at-a-distance Newtonian force of gravity acting on it, but as a response to the warping—the geometry of—space-time caused by the distribution of all other objects around it.
Moreover, as already discussed, according to the standard model, the particles of matter, the QL-atoms, combine with one another via the continual exchange of the particles of force. Recall, for example, that the attractive and repulsive electric force is really a manifestation of intricate particle collisions; even gravity is hypothesized to work via the exchange of gravitons. Matter and force are no longer distinct notions. Instead, forces are really expressions of complicated particle collisions.
And so, as is the view of Democritus, nature can be understood in terms of just particles and their complex collisions—forces were never required in the theory of Democritus and are no longer required in modern physics! Incidentally, although Empedocles’s two forces, love and strife, were separate entities from his four elements, still they were not action-at-a-distance types of force: via their direct contact, they either pushed the elements together to mix or pushed them apart to separate, so they
, too, in a way, acted as colliding particles.
Even mass, and consequently weight, is thought to not be a fundamental property of the QL-atoms, rather, a property the QL-atoms acquire through their interactions with the Higgs field. The mass of an object is a measure of its inertia, or of its resistance to a change in its state of motion. The smaller the resistance, the less the mass is. Throwing a baseball is easier than a bowling ball: the baseball has less mass than a bowling ball, or, equivalently, it produces less resistance to our attempt to throw it (and change its state of motion, from rest to moving). Now, the Higgs field pulls on the other particles (e.g., the QL-atoms) as they traverse through it and impedes their motion. It is this resistance that we interpret as mass. In an analogy, stirring a cup of coffee with a spoon is easy, but a cup of honey is not. Honey is a more viscous fluid, and the spoon feels heavier, more massive, as it moves through it. In this analogy, the spoon is a QL-atom and the fluid the Higgs field. Just as fluids with different viscosities cause the spoon that moves through them to feel lighter or heavier by impeding its motion, the standard model imagines that the all-pervasive Higgs field creates an analogous effect on the initially massless QL-atoms as they traverse it, endowing each with a unique mass and slowing them down. It is as if the Higgs field had different viscosity for different-type QL-atoms. Similarly, the force-carrying particles W’s and Z’s acquire their mass, but photons, feeling no resistance by the Higgs field, remain massless and thus can move with the speed of light. The analogy describes what is known as the Higgs mechanism, which explains why some particles have mass and some not (though it does not explain why they have the actual mass they do). What particular agent gives Higgs bosons their mass is nevertheless still an unknown. The idea that mass may not be a fundamental property was prompted by a few interesting and unresolved questions. Why, for example, is there no pattern in the mass values of the particles, a fact in contrast to other particle properties, such as spin or electric charge? For instance, in some units of measurement, the spin of all QL-atoms is 1/2 and the spin of all the force-carrying particles is 1.
Amazingly, mass is not a fundamental particle property, neither in the standard model of modern physics nor in Democritus’s atomic theory! Equally amazing is that in both the modern and the Democritean physics, the nonfundamental property of mass (and the consequent heaviness, weight) is caused (is acquired) by atomic motion—the motion of the QL-atoms through the Higgs field, and the motion of the D-atoms in the vortex!
Particles are by definition discrete entities; thus, their existence implies a certain discontinuity in nature. But is the nature of nature truly discontinuous?
Continuity Versus Discontinuity
If indeed something does exist always everywhere (including apparently empty space), then the essence of existence is continuous. At the same time, to make sense of the diversity in nature, the continuity of that which exists must vary, from place to place and from time to time. These variations are interpreted as discontinuities in matter and energy and are called particles. But what separates these discontinuities cannot be absolute nothingness, for energy is everywhere always. If the sea is the energy, the sea waves are the fluctuations of the energy, that is, the discrete particles of matter and the discrete particles of force. But even between the sea waves there exists water, the sea, energy, not nothing. So the view of modern physics is some kind of combination of the Parmenidean Being (of an indivisible, continuous whole obeying one eternal truth), the Heraclitean constant change (of everything in the sensible world), and the Democritean discreteness (of a whole, which while in essence continuous is also inhomogeneous and discrete, for it fluctuates). Now what exists must, we believe, be describable by a single idea or equation, a single type of particle, a theory of everything. Can the human intellect ever conceive it? What is the role of the senses in conceiving it?
Intellect Versus Senses
The taste of honey is relative (subjective) for Democritus, and the passage of time is relative (subjective) for Einstein. But both believe reality is objective. By contrast, the creators of the Copenhagen interpretation, Bohr and Heisenberg, think the moon exists only when we look at it; thus, reality is subjective. But Democritus also thought that reality is much deeper than what’s revealed by sense perception alone. Trying to capture both the unreliability and the significance of sense perception in our attempts to understand nature rationally, Democritus imagined a hypothetical dialogue between the intellect and the senses.
Intellect: “Sweet is by convention, bitter by convention, hot by convention, cold by convention, color by convention, in reality however there are but atoms and the void.”25
Senses: “Troubled Intellect! From us you take the evidence and you want to overthrow us? Our fall will be your fall.”26
The Intellect says that what’s perceived by the Senses is radically different from the way nature really is. Knowledge derived by the Senses is “obscure”27 but by the Intellect “authentic”28 (Democritus said). The Senses perceive sight, hearing, smell, taste, and touch, but these sensations are not objective properties of nature. They are only perceptions by convention (in relation to us, emergent properties), only a consequence of the atoms and their motion in the void—the objective truth, in other words, the true nature of things, is only atoms and the void the Intellect claims.
This might be true, the Senses respond, but though unreliable (“obscure”), the quest for knowledge always begins with sense perception. For the evidence of the atoms and the void is obtained through observation of colors, tastes, and so on, thus the participation of the Senses. It is what we see that we use in order to explore what we cannot see, the Senses emphasize. After all, “the phenomena [what is seen, appearances, occurrences] are a sight of the unseen,”29 said Anaxagoras. At the end, neither the intellect alone nor the senses alone can lead to the truth, but their combination might.
Conclusion
Leucippus’s and Democritus’s notion of indivisible (atomic), discrete particles without substructure has endured and, according to modern physics, is still one of the most remarkable properties of nature. Could space and time have an atomic nature, too?
* * *
1Sextus Empiricus, Against the Professors 7.135, trans. Erwin Schrödinger, Nature and the Greeks and Science and Humanism (Cambridge: Cambridge University Press, 1996), 89.
2Aristotle, too, by the way, didn’t account for his “natural motion,” down toward the earth. He just called it “natural.”
3Plutarch, Against Colotes 1110f–1111a, trans. Daniel W. Graham, The Texts of Early Greek Philosophy: The Complete Fragments and Selected Testimonies of the Major Presocratics (Cambridge: Cambridge University Press, 2010), 537(text 28).
4Aristotle, On Generation and Corruption 315b6–15. Or see Graham, Texts of Early Greek Philosophy, 541 (text 41).
5Ibid., 324b35–325a6, a23–b5, trans. Graham, Texts of Early Greek Philosophy, 529 (text 14).
6Sextus Empiricus, Outlines of Pyrrhonism 2.63, trans. Demetris Nicolaides. See Greek book Βας. Α. Κύρκος (Vas. A. Kyrkus), Οι Προσωκρατικοί: Οι Μαρτυρίες και τα Αποσπάσματα τόμος Β (The Presocratics: Testimonies and Fragments, vol. B) (Αθήνα: Εκδόσεις Δημ. Ν. Παπαδήμα, 2007), (Athens: Publications Dem. N. Papadima, 2007), 255.
7Graham, Texts of Early Greek Philosophy, 579–595.
8Although in truth, no experiment has thus far verified that the size of QL-atoms is absolutely zero, just that they are so super tiny that they may be treated satisfactorily as point-particles.
9Richard P. Feynman, The Feynman Lectures on Physics (Boston: Addison-Wesley, 1963), 1–2.
10Leon Lederman and Dick Teresi, The God Particle: If the Universe Is the Answer, What Is the Question? (Boston: Houghton Mifflin, 1993), 340.
11Aristotle, Metaphysics 985b4–20. Or see Graham, Texts of Early Greek Philosophy, 525 (text 10).
12Simplicius, On the Heavens 242.15–26, trans. Graham, Tex
ts of Early Greek Philosophy, 533 (text 23).
13Bertrand Russell, The History of Western Philosophy (New York: Simon & Schuster, 1945), 71.
14Plutarch, Against Colotes 1108f–1109a, trans. Graham, Texts of Early Greek Philosophy, 527 (text 13).
15Isaac Asimov, Understanding Physics (xx: Dorset Press, 1988), 7.
16Lederman and Teresi, The God Particle, 44.
17Banesh Hoffman, The Strange Story of the Quantum (New York: Dover, 1959), 68.
18Brian Greene, The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory (New York: W. W. Norton & Company, 1999), 114.
19Katherine Freese, The Cosmic Cocktail, Three Parts Dark Matter (Science Essentials) (Princeton, NJ: Princeton University Press, 2014), 195.
20Jeffrey Bennett, Megan Donahue, Nicholas Schneider, and Mark Void, The Essential Cosmic Perspective, 7th ed. (Boston: Pearson, 2013), 479.
21Werner Heisenberg, Physics and Philosophy: The Revolution in Modern Science (New York: Harper Torchbooks, 1962), 40.
22Aëtius 1.3.18, S 1.14.1f. Or see Graham, Texts of Early Greek Philosophy, 537 (texts 31, 32); Cicero, On Fate 20.46. Or see Graham, Texts of Early Greek Philosophy, 537 (text 33).
23Aëtius 1.4.1–4. Or see Graham, Texts of Early Greek Philosophy, 541–545.
24Charles W. Misner, Kip S. Thorne, and John Archibald Wheeler, Gravitation (Princeton, NJ: Princeton University Press, 2017), 5.
25Sextus Empiricus, Against the Professors 7.135–37, trans. Demetris Nicolaides. Or see Graham, Texts of Early Greek Philosophy, 595 (text 136).
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