The Search For a Theory of Everything
“The most remarkable property of the universe is that it has spawned creatures able to ask questions.” ~ Stephen Hawking
Introduction
From quantum mechanics to general relativity, physics and its theories are diverse and scattered but imagine a theory that binds all of it together, that can explain all aspects of our universe, including its fundamental forces and building blocks. This is what the hypothetical Theory of Everything aims to achieve. For ages scientists have worked tirelessly in the hope of developing this theory. Fabricating this has also been an unaccomplished dream of two legendary physicists - Albert Einstein and Stephen Hawking. This theory instills hope to find answers to countless questions, such as why positive and negative charges exist, why quantum numbers exist, and why an electron has mass and never decays.
What is the Theory of Everything?
Almost all scientists agree that no matter how successful a TOE may be, it will never be able to explain everything. When physicists think of a TOE, they mean something very specific. “What they’re talking about is unifying all the forces of nature into a single one,” says physicist Katherine Freese, a professor at the University of Texas at Austin.
Physics is broadly divided into two sections - General relativity and quantum mechanics. While general relativity focuses on gravity to understand the large-scale objects in the universe, such as planets, stars, and black holes, quantum mechanics uses the Standard Model, which encompasses three major non-gravitational forces to understand particular and low-mass physics.
Standard Model explains three of four fundamental (except gravitaional force)that govern the natural world: the electromagnetic force that holds atoms and molecules together through the interaction of their electrically charged components, the strong nuclear force which binds elementary particles called quarks into more complex protons, neutrons and electrons (and subsequently into atoms), and the weak nuclear force responsible for radioactive decay.
The major problem here is that these four fundamental forces of gravity, electromagnetic, and strong and weak nuclear forces are incompatible when applied together. On the sub-atomic scale, Einstein’s view of gravity fails to comply with the quantum rules that govern the elementary particles, while on the cosmic scale, black holes are threatening the very foundations of quantum mechanics.
Einstein attempted to unify general relativity and particle physics.
In modern physics, the TOE is nothing but the unification of these fundamental forces into a greater single force or simply a theory that unifies all of these fundamental forces into a single explanation.
Current theories attempting unification-
1) String Theory- The String Theory is perhaps the most high profile candidate for the TOE. Even with a few drawbacks it is able to describe the entirety of the known universe. The string theory states that everything in the universe, from protons to electrons, is made up of unbelievably tiny string-like structures instead of point-like particles. These strings vibrate in different ways and the type of vibration it has will decide the kind of matter it would form. For eg, if it vibrates in a certain directio,n it will form a proton and if in another then it will form a neutron. The theory satisfies the principles of both quantum mechanics and general relativity.
In order for that to work, string theory has to make one more radical assumption. Instead of living in a universe with three dimensions of space and one of time, we live in one with either 9, 10, or 25 dimensions of space. This theory states that these extra dimensions are curled up or compactified at very small scales, making them undetectable by our current technology.
This process of curling up, or “compactification”, can be done in countless billions upon billions of different ways. Each compactification produces a different spacetime, meaning that string theory can realistically predict a multiverse populated by 10^500 different universes.
This theory, however, comes with a few drawbacks, making it vulnerable to debate and criticism. Some of them lack experimental evidence, require too many dimensions, or are too detached from physics.
2) Variations of the String theory -
->Superstring Theory -This version of string theory states that the universe consists of 10 dimensions. These include the 3 dimensions of space, 1 one of time, and 6 other hidden dimensions. But where are these 6 hidden dimensions present?
Let's take an example to understand this. We look at a distant planet through a telescope. It appears like a dot, which is zero dimensional. If we attach two of these dot-like planets, we get a line that is 1 dimensional. If we get closer to one of these planets, they appear like circular 2d objects, and getting further closer, we realise that they are actually 3d spherical objects. Now you would probably notice that when we get closer to an object, we are able to perceive more dimensions
So the superstring theory states that as we get closer to an object, we will be able to percieve these 6 hidden dimensions but they are so small that we are not able to currently perceive them even through the most powerful microscopes or particle colliders. Every point in our familiar 4D space-time (3D space + time) has a tiny 6D shape attached to it — like a super-microscopic ball of twisted space.
->M Theory: Apart from the fact that instead of one there are five different, healthy theories of strings (three superstrings and two heterotic strings), there was another difficulty in studying these theories: we did not have tools to explore the theory over all possible values of the parameters in the theory. Each theory was like a large planet of which we only knew a small island somewhere on the planet. But over the last four years, techniques were developed to explore the theories more thoroughly, in other words, to travel around the seas in each of those planets and find new islands. And only then was it realized that those five string theories are actually islands on the same planet, not different ones! Thus there is an underlying theory of which all string theories are only different aspects. This was called M-theory. The M might stand for Mother of all theories or Mystery because the planet we call M-theory is still largely unexplored.
One of the islands that were found on the M-theory planet corresponds to a theory that lives not in 10 but in 11 dimensions. This seems to be telling us that M-theory should be viewed as an 11-dimensional theory that looks 10-dimensional at some points in its space of parameters. Such a theory could have as a fundamental object a Membrane, as opposed to a string.
Many other theories like the Loop Quantum Gravity, Grand Unified theories, and Holographic Principle also compete with the String Theories to become the TOE, but none of them have been very accurate.
The impact of developing a TOE -
A common question that comes while thinking about a TOE is “Will developing this theory mean the end of physics?”. The answer to this is definitely no. It is like saying that developing a periodic table would mean the end of chemistry. A working theory of everything would certainly change a lot of things about physics, but it wouldn't be the end of science by any means.
A theory of everything would not bring us much closer to understanding large-scale emergent phenomena like life, consciousness, or superconductivity. In fact, most fields of science - biology, chemistry, geology, and so on — would be almost completely unaffected.
However, one thing that the theory surely promises is the understanding of particle physics in relation to gravity. This would, in turn, enable us to know why various things exist around us in the way they do.
Conclusion
The Theory of Everything might not give us every answer we’re looking for, and it probably won’t solve all the mysteries of science. But that doesn’t make it any less important. The search for this theory pushes us to ask bigger questions, think in new ways, and bring together ideas that once seemed completely separate. It encourages scientists to work together and explore deeper into how the universe works. Even if we never find one final answer, the journey itself leads to new discoveries, better technology, and a greater understanding of the world. That’s why the Theory of Everything is still such a powerful and meaningful idea and it makes it worth striving for.
References
Will Scientists Ever Find a Theory of Everything? | Scientific American
A maverick's quest for quantum gravity – Physics World
What is string theory? | New Scientist
tc.cam.ac.uk/outreach/origins/quantum_cosmology_four.php
How Would A Theory Of Everything Impact The Rest Of Science?
Comments ()