By Amjid Abdullatif Khurwat | Staff Writer

During the mid-twentieth century, German physicist Heisenberg, came up with a hypothesis within quantum mechanics that the fabric of the universe is discontinuous, or pixelated – that is, it consists of indivisible countable values. But then Einstein and a number of scientists opposed this hypothesis and came up with a corresponding one that states that the fabric of the universe is connected, in other words, if you take any two points on this fabric, the distance between them will be infinite – you can divide it into an infinite number of values.

Although this controversy has not reached a conclusive result, and it is very difficult to test the validity of these two hypotheses in practice, physicists and cosmologists are still researching this question as the European Space Agency (ESA) is overseeing one of the largest projects to attempt to probe this question. We will address this at the end of this article, but beforehand we need to know more about the “fabric of the universe” which we usually describe as “space”.

General theory of relativity and smooth space-time

What is space? This question may seem arbitrary. We could say that space is just that place where all things are, right? Not quite, space is actually more than just a stage where things exist. Imagine if we stopped for a moment, and removed all the things around us until we were left with nothingness; remove buildings, cars, people, etc. What if we removed the Earth itself and all the planets and stars? Literally everything from the smallest atom to the largest galaxy. What will we have left? Nothing, right?

If we asked this question to Newton, his answer would have been “yes”. Space for Newton is an absolute and constant stage in which all events take place, but for Einstein, and here lies his true genius, this idea didn’t cross him as comfortably as it did us. He discovered that space itself is more than a mere stage. He discovered that space is in fact an active actor; it plays a major role in the cosmic drama! Einstein realized that space is as connected as a fabric called the “space-time”, denoting the interconnection of space and time and their influence on what objects do on this fabric. Gravity, for example, is nothing but a curvature caused by objects in this fabric. Einstein called his theory the “general theory of relativity”. It describes space as a continuous space-time fabric that affects and is affected by objects. It is one of the main theories of modern physics and one of the most consistent scientific theories ever!

Quantum theory and pixelated space

In that same era and based on the idea that Max Planck and Albert Einstein came up with in 1905 – one about black body radiation and the fact that light is quantized packets of energy known as photons – a second major theory of modern physics emerged to the world. That is quantum theory, which is also known as “quantum mechanics”. 

Quantum mechanics describes the tiny particles in the universe, such as electrons and photons, and describes their interactions accurately. It is based – as its name suggests – on the idea that energy, momentum and other properties of matter come in “quanta”, meaning that they all come in the form of discontinuous packets.

This theory was the result of many scientists wondering about the following question: “what is the shortest length?”. In other words, just as the speed of light is the speed limit in the universe, what is the shortest possible length in the universe? As some of you might know, the answer is (Planck’s Length), which is: 

(0.000,000,000,000,000,000,000,000,000,000,000,016 meters) or 1.616229×10^(−35) meters

Don’t worry if you can’t read this number, it’s hard to tell how small this length is because any small thing you can think of would be much, much longer (for example, the hydrogen atom itself has a diameter at least 10 trillion times larger than the Planck’s Length!).

So according to this fact that says that there is no length shorter than the “Planck’s Length”, this means that there is a minimum length in the universe, and therefore it is similar to the pixels in the image on your phone screen, which seem connected and smooth from a distance, but when we zoom in enough, we find that it is made up of discrete units known as pixels. The universe may also actually be pixelated, that is, it consists of discrete, ultra-small units. This is exactly what was proposed by one of the founders of quantum mechanics, physicist Werner Heisenberg. He described the movement of subatomic particles as occurring in the form of jumps instead of continuous gradual flows from one place to another, which is an indication that space is discontinuous and not infinitely connected. Some scholars supported this hypothesis and others opposed it. There is still a controversy to this, and it won’t cease to be one until one of the two hypotheses is proven to represent the reality of things.

GrailQuest project and the quest to know the nature of reality 

Now that we have a good idea of ​​the smooth space-time and pixelated space-time hypotheses, we will talk about the latest and largest project that is being launched by the ESA to have a clearer idea of the issue at hand. That is the GrailQuest (Gamma Ray Astronomy International Laboratory for Quantum Exploration of Space-Time) project. It is based on the following basic idea: If the fabric of the universe is indeed discontinuous/pixelated, the speed of light will not be completely constant through it but will change slightly depending on the energy of the light. Since light with higher energy (such as gamma rays) has a shorter wavelength, then when the wavelength becomes short enough, it can be affected by the disruption in this supposedly discontinuous space-time.

Researchers working on this project aim to test this idea by observing gamma ray bursts in space through a fleet of advanced satellites, part of which has been launched in December of 2021. However, the project is long-term, and the decisive results are expected to be obtained between 2035 and 2050.

If we can find evidence that the fabric of the universe is either smooth or pixelated, it will not only begin to reshape our knowledge of reality but will even open the door to a revolution in the world of physics, and perhaps followed by a revolution in the world of space navigation and its technologies. While we are waiting for the answers to this question, let us go even deeper into the mysteries of the universe and think about whether this present moment in time is smooth, or pixelated?!