On the nature of metaphors

Published on by Catherine Toulsaly


As we envision the possibility of a human mission to Mars in a not-so-distant future, we are waiting on the spacecraft InSight to send out all the data on the planet's vital signs after its landing on November 26th of last year. ESA's Mars Express captured its amazing bird's-eye view throughout its fifteen-year history. Our mind allows us to identify with a spacecraft or an asteroid as if we were out there making discoveries. Over the next 20 months, data will pour in from New Horizons' flyby of Ultima Thule, the furthest object in the Kuiper belt to be visited beyond the known world. Ultima Thule in the infinite darkness reminds me of a floating body whose hippocampal place cells act as a sensor in the depths of space. Would its body feel the Universe expansion through the pulling of dark energy? We find a sense of belonging in knowing that the Kuiper belt, in many ways similar to the asteroid belt, is not specific to our solar system but a feature that can be observed in other stellar systems.

Ultima Thule

Ultima Thule

Against the backdrop of rigorous mathematical equations stands the poetry of metaphors. Terms like flashes, butterfly effect,  cosmic censorship, and moonshine are first and foremost metaphors that a larger audience is thankful to have to catch a glimpse of what lies beyond our earthly life. Hypotheses are meant to be proved or disproved. They continue to resonate and leave behind a trail of academic papers. The cosmic censorship was formulated by Roger Penrose to assert that “one cannot see the singularity itself from outside. In particular, it implies that there is some region that cannot send signals to external infinity.” (The Nature of Space and Time,  p.29, Princeton University Press, 2010)



“Beyond” is one of those words that just wants you to push the door to the unknown and take a mental or visual peek at what is beyond. Could time and consciousness really be the same? I ask. Consciousness defines a continuous flow. Even when, in the present moment, our mind stops wandering between the past and the future, our heartbeats, our lungs breathe the air in and out, and our ears hear sounds of motion that are evidence of the existence of consciousness and the passing of time. Some might say that time is an illusion. We wonder then if it is because of our deluded brain or whether we have not yet reached a level of understanding sufficient to see our Universe as it really is. As far as we can remember, humans have been wondering about a time before time. Some say that time existed before the Big Bang and that it hardly was a beginning, just a rebound. Time preceded time.

A key question in the study of cosmological singularities is whether quantum gravity mediates a bounce from a big crunch. Is a cosmological singularity a true end to spacetime or is there another semiclassical region of spacetime before a big bang or after a big crunch?

Netta Engelhardt and Gary T. Horowitz


In a 2015 paper on Holographic Consequences of a No Transmission Principle (NTP), Netta Engelhardt and Gary T. Horowitz stated that it is because of the NTP that holographic quantum gravity generally forbids bounces through cosmological singularities. So how do black holes behave? For different black holes, there are different interpretations and different theories. Does singularity extend to infinity? And if the holographic principle is applied to black holes - meaning that the information is embedded onto the edge - is it compatible with the idea of a white hole?

“The No Transmission Principle implies that there is no evolution past this singularity into another asymptotic region in holographic quantum gravity”

Netta Engelhardt and Gary T. Horowitz


In a 2016 paper on Charge diffusion and the butterfly effect in the striped holographic matter, Andrew Lucas and Julia Steinberg stated that several recent works have pointed out that the holographic interpretation of the butterfly effect is a geometric shock wave propagating along the horizon and that black holes could be maximally extended to “double-sided” geometries, which contain two copies of the field theory, where time runs in opposite directions, along with a black hole and a white hole. Within the supersymmetric spectrum of a black hole, matter and force intertwine. Are string-like waves called branes traveling in a solitary manner through wormholes from a black hole to a white hole? Why do black holes have entropy anyway?

Only when we can answer this question can we ever claim that we understand the nature of quantum gravity

Miranda Cheng

A supermassive black hole in action

A supermassive black hole in action

And why was entropy low in the past? In Carlo Rovelli’s description of time’s arrow as perspectival, he explains that the reason why we experience time the way we do is a so-called “coarse-graining effect” that I understand as the uncertainty that we face as observers when we attempt to measure the actual value of past and future events. The question of time touches upon our role as observers.


Physicists have often expressed the wish for a quantum theory without observers, i.e., a formulation of quantum theory that is not fundamentally about what observers will see if they carry out certain experiments, but instead about an objective reality. In such a theory, the quantum formalism gets derived (from the laws governing the objective reality) rather than postulated. One quantum theory without observers was presented by Ghirardi, Rimini, and Weber

Roderich Tumulka

Consciousness spreading upward and downward, backward and forward in time relies on the nature of numbers and their importance to understanding the Universe through conscious and unconscious quantification of our surroundings. How many dimensions are there anyway? The classification of the finite simple groups is a unique mathematical theorem that describes what all the finite simple groups look like. The 26 sporadic groups are finite simple groups unrelated to the infinite families, the Monster group being the largest. The way I understand it is that the members of the Monster group create a symmetry group of some structure that repeats itself with 196 883 dimensions. In my mind, I have the image of every footstep I took, every distance traveled in the air, on the sea, underground, and around the globe since birth; retracing them would form a web-like monster life structure with real-life events that I imagine could be mathematically described as spacetime points. According to the Ghirardi, Rimini, and Weber theory, “the world is made of flashes (events in spacetime), and the wave function serves as the tool to generate the ‘law of evolution’ for the flashes.”

Is every step I make part of an already-defined course of events or a random balancing act between non-locality and causality? In our empirical inquiry into the nature of matter, there seems to be no place to study consciousness and time. Why can we physically touch neither consciousness nor time, but still, we feel them both through our body and mind? “If no one asks me, I know: If I wish to explain it to one that asketh, I know not” (The confessions of Saint-Augustine, translated by Edward Pusey)Within the realm of perceptions stands the mystery of time and consciousness. I found it interesting that scientists rely on reason and empirical evidence but still follow their intuition in their quest for answers. Netta Engelhardt and Gary T. Horowitz mentioned that the principle they employ is intuitive. What does that mean when scientists say “this or that agrees with intuition”? Theorists and artists alike pursue an ideal truth. There is indeed an intangible line between truth and reality. A truth that is proved and demonstrated through empirical experimentation becomes part of reality. In the long and complex process that leads to uncovering new realities, those who wish to harness the power of their imagination are engaged in a dialogue on a rocky path.

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