Analysis: There are gazillions of different possible universes that can be described and understood using the tools provided by string theory
If we look out into the sky on a clear night, all we see is tiny white dots on a black background. It seems like the universe is made up of dots. Dots, in their purest form, have no extent. They have no length, no area and no size. Dots are zero-dimensional.
If we take a closer look, we might observe that the tiny dots in the sky are actually not dots, but stars like our sun. Our sun appears to be a hot ball of gas up in the sky. If we try to understand what heats it up, we have to go from the gigantic scale of stars to the miniscule scale of atoms. An atomic process — fusion, where atoms are smashed together into bigger atoms, releasing surplus energy — powers the sun and other stars. For many of these processes, the atoms themselves can be crudely approximated as dots again. It really looks like our Universe is a fan of pointillism.
From Kurzgesagt, string theory in a nutshell
As it turns out, the interior of atoms is no longer easily described by dots. The core of an atom contains neutrons and protons. This is a bit surprising, given that neutrons are neutral and protons are all positively charged. Things of equal charge repel each other. If you take two magnets to play with, you might find that there are spots where the two magnets attract each other and stick together, and spots that repel each other. It takes quite some force to bring the repelling parts closer together. The repelling parts are of the same charge. Opposite charges attract each other, equal charges repel each other.
Why don’t the atoms fall apart, with having all those protons that repel each other? As it is with magnets that require some force to push them together, the protons can also be pushed together by force, namely the strong nuclear force. This force keeps the protons together. It can be overcome in heavier atoms, which explains nuclear fission, where heavy atoms decay into lighter ones. There, the strong nuclear force was not strong enough to keep everything together.
To gain a more profound understanding of the strong nuclear force and the building blocks of atoms, a mathematical description had to be found. In classical physics, the fundamental building blocks of nature are zero-dimensional point particles that are characterised by a mass and charges. In the late 1960s, it was realised that equations that describe vibrating strings and loops can also be used to describe the interior of atoms.
From StarTalk podcast, is the universe made of tiny vibrating strings?
This was the birth of string theory, where the fundamental building blocks are strings that have a length and different modes of vibrations. Having a length makes the strings one-dimensional. All the fundamental particles from classical physics and their masses and charges are described by different vibrational modes of a string in string theory, just like the string of a fiddle can produce different notes.
Going from point-particles to strings might sound like a small change. Yet, for physicists, it is a fundamental transition that demands a wholly new way of thinking as well as novel mathematical methods. The mathematical framework got extended over the years, to include other particles, and even other forces, including gravity.
A theory must make testable predictions. String theory provides us with tools to construct models, yet, with the tools we developed so far, no unique and falsifiable predictions have been made. This renders the term string theory something of a misnomer. In its current form, it is more comparable to a mathematical toolbox. The mathematical tools offered by string theory let us describe the interior of atoms, black holes, gravity and entire universes.
We need your consent to load this rte-player contentWe use rte-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences
From RTÉ Radio 1's Morning Ireland, astronomers find black hole 33 times bigger than the sun in Milky Way
However, just handing you the tools does not predict what kind of table you will build. If I hand you a toolbox and ask you to construct a table, the outcome of this endeavour is hard to predict. There are so many possible tables to be constructed! Some would be unstable and collapse. Others would be round with three legs. Maybe you would produce a small coffee table. Others might come up with a monstrous piece of furniture that hosts 30 guests in an opulent dining hall.
The same holds for string theory and the description of our universe. There are gazillions of different possible universes that can be described using the tools provided by string theory. We haven’t succeeded in constructing exactly the universe we are living in yet. We are still learning to use the tools and are still developing and adding new tools.
String theory provides us with a wealth of new ideas, but we need to further focus on research, science, and education to master the tools it provides us with
String theory as a mathematical framework has influenced many areas of physics. This includes models of dark energy and dark matter; ideas about the very early Universe and a phase of rapid expansion called inflation, where the Universe massively grew in size within a split-second; and black holes.
String theory as a framework has also brought mathematical advances in geometry, topology and algebra. Some current developments might lead to future progress in quantum computing, material sciences, medical imaging, or data storage, computational algorithms and cryptography.
String theory provides us with a wealth of new ideas, but we need to further focus on research, science, and education to master the tools it provides us with.
Follow RTÉ Brainstorm on WhatsApp and Instagram for more stories and updates
The views expressed here are those of the author and do not represent or reflect the views of RTÉ
