TUESDAY, 3 AUGUST 2021Say you were robbed of all but one of your senses, which would you rather not lose? Unsurprisingly, an overwhelming majority would choose their sense of sight. In fact, we estimate that about two-thirds of our brain is involved in processing visual information. We, as a species, interact with the world primarily through our vision. However, the human eye, as complex an organ it may be, is still rather limited. The smallest objects that the naked eye can resolve are about 0.1mm, and the furthest objects we can see are the indistinguishable twinkles of starlight. It is no wonder that throughout history, people have devised various apparatuses to supplement our rudimentary vision, inasmuch as to augment it with the very forces of nature.
From the ancient Egyptian’s depiction of glass meniscal lenses in 2000B.C., the Mesopotamian’s use of the Nimrud lenses in 700B.C., and 1st century A.D. Roman philosopher Seneca's application of refractive crystals in perusing fineprints and spectating distant gladiatorial showdowns, optical technologies have come a long way in their intricacy, clarity, and capability. Most notably, in 1609, Galileo Galilei pointed an array of calibrated lenses to the heavens for the first time and observed the hitherto unseen moons of Jupiter, pioneering the field of observational astronomy. Interestingly, in the same year, Galileo made a few tweaks to his telescope, flipped it around, and invented the first compound microscope.
Since then, optical technology has become an indispensable and ubiquitous visual aid. Today, we can zoom in to the scale of individual atoms with transmission electron microscopes and atomic force microscopes. At the other extreme, the Hubble Space Telescope sheds light on Icarus, a star halfway across the universe nine billion lightyears away, the farthest observed yet.
The Electromagnetic Paradigm
Nonetheless, even with the mind-boggling sophistication that enabled these powerful devices, the fundamental principle is consistent — they are all manifestations of electromagnetism. Optical microscopes reflect and refract light into useful geometries, the Hubble Space Telescope detects signals from the infrared to ultraviolet spectrum, and even the electron or atomic force-mediated apparatuses exploit the electrostatic interactions between particles. In fact, you can even say that almost all human inventions, interactions, and experiences predicate on this medium.
You take a spoonful of hot chicken soup. It stays in the spoon and doesn’t fall through because of the electromagnetic repulsion from the metal atoms. You get distracted by Netflix and spill the soup on your thigh, your pain receptors mobilise waves of potassium and sodium ions that bind to ion channels down a chain of neurons to tell your brain: “ouch”. You call mum with your phone, made with semiconductors, transistors and other electronics, and you ask her how to soothe a bad scald, your voice carried by radiowaves across the globe to your worried mother. Yes, it always has been electromagnetism.
Forces of Nature
However, electromagnetism is not the only force of nature. At the frontier of particle physics, scientists have established the Standard Model, describing a collection of elementary particles of matter and energy, smaller than even protons and neutrons, as the all-encompassing constituents of the universe. In theory, if we can understand precisely the properties and interactions of each particle, we will have a complete description of nature and the laws governing it. With this knowledge, every chemical reaction, biological process, and cosmological phenomenon can be impeccably modelled. That is, if we understand the Standard Model to infinite precision and have infinite computing power.
The point of introducing this exotic theory is not to comment on the plausibility of a ‘theory of everything’, but to bring to light the fact that the model describes not one, but three fundamental forces. The omnipresent electromagnetic force is mediated by particles of energy termed photons. The strong nuclear force and weak nuclear force governing the subatomic realm are carried by particles named gluons, W bosons, and Z bosons. Unlike electromagnetism, which permeates the whole universe, and whose reach extends ad infinitum, the nuclear forces are, as the name suggests, confined within dimensions smaller than an atomic nucleus. With its counterparts barely manifesting on the scale of our human experience, it is no surprise that we regard electromagnetism as the singular conduit of nature.
So far, we have been avoiding the elephant in the room. There is a fourth fundamental force much like electromagnetism, which facilitates the interaction between all things, whose range knows no bound. This entity, excluded from the Standard Model due to our lack of understanding, is all-pervasive but remains the most mysterious. We are of course talking about gravity. We know so little of gravity because it is weak. So weak that its magnitude is 1038 times weaker than the strong nuclear force, 1036 times weaker than the electromagnetic force, and 1029 times weaker than even the weak nuclear force.
A Resounding Success
We seem to have steered quite far from the theme of optical technology. However, where we are heading now is in fact the way forward. Recent discoveries have highlighted that despite all the razzle-dazzle we can do with light, we are still mostly in the dark. Indeed, there is truly more than meets the eyes. And now, it is time to break a few paradigms from time immemorial.
Far out in the unremarkable corners of the desolated lands of the North American continent lie two oddly shaped facilities with long, orthogonal arms. On 14th September 2015, a few beams of laser bounced about in these arms to create strange patterns and everyone cheered. The first direct detection of gravitational waves had been made at the Laser Interferometer Gravitational-Wave Observatory (LIGO). Gravitational waves are a type of periodic oscillation. Specifically, like how sound waves are the compression and expansion of air molecules, gravitational waves are the cycles of stretching and squeezing of space itself. The particular gravitational waves detected at LIGO originated from two black holes 1.4 billion lightyears away. Their perpetual inward spiral ended in a cataclysmic merger, and the sheer impact of this marriage resonated through the universe like a cosmic church bell.
This discovery was so exciting for three reasons. Firstly, we had proven Einstein right, yet again. The next cause for celebration was the incredible engineering feat involved in the detection. As mentioned, gravitational effects are extremely weak, and even the collision of two cosmic monstrosities could only produce a stretch in spacetime a thousandth of the width of a proton. Yet, this minute signal was detected and isolated from chaotic background noises. Finally, and most crucially, the discovery opened the door to a whole new way of observing the universe. Thus far, we have been blind to half of the happenings in the cosmos. But now, we have set the precedent for seeing the world in a completely new way.
A Bright Future
The potential of ‘gravitational optics’ is limitless. Recall how much progress we have made as a technological civilisation since we learned to wield light to our advantage. If we were to be able to harness gravity and bend it to our will as we do with light, then near-light speed spacecraft, artificial gravity, and even micro black holes would just be a few technical problems away. The world truly changes when you change your perspective and see it in a new light.
Xavior Wang is a first year NatSci at St Edmund's College. Artwork by Pedro Riera.