Spiral Out

person holding artwork

Spiral Out – Goro Horie

On April 10 2019, the first ever direct image of a black hole was released to the public. It was taken by the Event Horizon Telescope Collaboration (EHTC), using an array of eight radio telescopes strategically placed around the globe. The image instantly became iconic, being plastered in every possible corner of the internet. It was named PowehiI , a hawaiian word that loosely translates to “embellished dark source of unending creation”.
Having only been exposed to the existence of black holes in sci-fi books and film before this class, the image provided by ETHC was momentous. This class had taught me the concept of the scale of the universe and the magnitude of violence a black hole actually manifests. Seeing what was merely numbers, theory, and a whiff of my imagination materialized before my eyes was horrifying and exciting simultaneously.
The image of the black hole was groundbreaking beyond its technological undertaking. It allowed scientists to verify the General Theory of Relativity (GTR) with observational evidence. The artwork that I chose to create was one that aims to explore the very nature of black holes and how photons behave around the event horizon.
Perhaps the most notable aspect of the image is the striking orange ring around the black hole itself. This is called the accretion, which is one evidence for the fact that matter around the black hole spirals inwards towards the center. The massiveness of the black hole implies that matter orbits around it and the glow proves that matter is losing gravitational energy and thus angular momentum, which causes the matter to fall into the black hole.
However, the intensity of the glow is higher than what can be expected since the gas around the black hole is too dilute for conventional friction to be reasonable. Further studies using the data measured by EHTC may hopefully answer the peculiar nature of the accretion.
The glow of the black hole prompted me to explore how light behaves around the black hole. Upon further research, I discovered the gravitational red shift. This was initially predicted as an extension of the GTR using the mass-energy equivalence.
As light travels away from the event horizon of the black hole, the photon expends energy in order to gain gravitational potential energy. The formula for gravitational potential energy necessarily expresses the proportional relationship between the gravitational potential energy and the product of two masses interacting with each other. The formula of gravitational potential energy (Ug) in this example is shown below:

Where G is the gravitational constant, M is the mass of the black hole, m is the “mass” of the photon, and r is the distance between the black hole and the photon.
The world famous e = mc2 allows the “mass” of the photons to be expressed in terms of its energy and overcomes the problem of the massless nature of a photon. Since the energy of the photon can be expressed as e = hf , where h i s Planck’s constant and f is the frequency of light. Combining the aforementioned formulas, gravitational redshift can be explained:
1. First, expressing the photon “mass” in terms of h, c, and f:

2. Second, using the law of conservation of energy,
initial energy of photon − Δgrav. potential energy = final energy of photon

Which implies that the observed/final frequency f’ is smaller than initial frequency f .
Using these concepts and the knowledge I gained from class to perceive the space-time continuum as a 2-dimensional space, where space is one axis and time is the other, I used string art to merge the depiction of space-time, gravitational red shift, and accretion. I attempted to mimic its fabric/weave-like nature, provide a spectrum of colors tending towards red from the center, and demonstrate the spiral. The challenge was to create a layered effect to depict the movement of light from the center outwards. I did this by creating a circle using 180 nails and using sewing thread of different colors. I skipped every 8th nail, so that the lines created by the nail would shrink at a constant rate, allowing for the intended effect. I also overlapped the thread when I changed the color so that it had a blending effect. I decided to spray paint the wood board black to allow the audience to focus on the spiral. The black was also intended to mimic the nature of the black hole beyond the event horizon where no light escapes.