Waiting for Unity: When Will We Get a Theory of Everything?

FROM THE LECTURE SERIES: UNDERSTANDING THE MISCONCEPTIONS OF SCIENCE

By Don Lincoln, Ph.D.Fermi National Accelerator Laboratory (Fermilab)
A view of the universe captured by the Hubble Space telescope.
A theory of everything will need to explain everything in the universe, from subatomic particles to galaxies. (Image: NASA, ESA, H. Teplitz and M. Rafelski, A. Koekemoer , R. Windhorst Z. Levay / Public domain)

From Atoms to Quarks

On the building blocks side, the original idea of atoms arose with ancient Greek philosopher Democritus, a couple of hundred years BC. A more modern understanding of atoms was developed in the late 1700s, when chemistry started to become a well-explored discipline.

The first real confirmation of the idea of physical atoms was written down in 1905 by Einstein. The electron was discovered in 1897, while the proton and neutron waited until 1919 and 1932, respectively. And quarks were discovered in the mid-1970s.

So you could say that it took us something like 200 years to go from a fairly firm proposal of chemical atoms in the 1770s or so to the observation of quarks in the 1970s. That’s sort of the basic time frame for progress in the understanding of the building blocks of matter.

Learn more about quantum entanglement.

The Development of Force Theory

On the force side, the timescales are comparable. Newton unified gravity in 1670, while Maxwell’s unification of electromagnetism was in about 1870. There was a more recent unification of electromagnetism and the weak nuclear force in about 1970. So, those successes took about 300 years. And of course, 1970 was about half a century ago.

When you look at things this way, you get a more reasonable idea of how long it will take to make further progress. There’s no way that a theory of everything is just around the corner. Even given the advance in technology of the last century, we’re talking about a process that will take centuries or maybe even millennia.

So, it might be interesting to get an idea of what the path forward might look like. Let’s start with how modern scientists imagine that we might unify the forces. There is a great image that kind of gives the idea. We successfully unified celestial and terrestrial gravity and, separately, electricity and magnetism. So, where we are now is that we have the 4 forces: gravity, electromagnetism, the weak nuclear force, and the strong nuclear force.

This is a transcript from the video series Understanding the Misconceptions of ScienceWatch it now, on The Great Courses Plus.

The 3 Fundamental Forces and a GUT

Higgs boson in large hadron collider.
The discovery of the Higgs boson seemed to indicate that the idea of a electroweak force is true. (Image: Master_Andrii/Shutterstock)

There was a proposal in the 1960s that electromagnetism and the weak force actually come from a deeper and more fundamental force called the electroweak force. That idea seems to be true. You might have heard about the discovery of the Higgs boson back in 2012. That was the confirming discovery.

Thus, it might be more accurate to say that there are now only 3 forces: gravity, the strong nuclear force, and the electroweak force. Scientists imagine that perhaps we will one day unify the electroweak force and the strong force. We even have a name for it; we call it the grand unified theory, or GUT. And then, after that, we think that perhaps we can unify the GUT force with gravity and have a theory of everything.

Learn more about the search for a unified field theory.

The Many Unknowns

If you’re a physics buff, you’ve no doubt seen figures that show the imagined connections. It’s a reasonable idea, and it might be right. But before we believe it, we need to remember a lot of things. First, the kind of matter that makes up you and me is only 5% of the matter and energy of the universe. Ninety-five percent of the universe is made of dark matter and dark energy, or at least we think this is true. Strictly speaking, we aren’t even sure. But the key point is that if this unification picture is correct, we need to figure out where dark matter fits in.

In addition, we don’t understand why the universe is made of matter. Einstein’s theory of special relativity says that energy can turn into matter and vice versa. But when energy turns into matter, it should make an equal amount of antimatter. And that’s what we think had to have happened after the big bang. The universe somehow got rid of the antimatter and left only matter. We don’t know how that works either. So that’s another piece in the puzzle that has to fit in somewhere.

Image of a nebula
There is lot that we do not understand about the universe, including the dark matter. (Image: Marcel Drechsler/ Shutterstock)

There’s another reason to be cautious. Fundamental physics theories span a huge amount of energies. The energies we explore at the frontier of knowledge are about 10 trillion times higher than the energies of chemistry. But the energy at which we kind of think that gravity unifies with the other forces is a quadrillion times higher than what we can achieve with today’s technology.

The Unimaginable Future

It’s pretty ridiculous to think that we won’t discover things that we can’t even imagine yet. Whatever we imagine might be the future, there are huge surprises in front of us.

What we’ve done thus far is to explore just the foothills—an impressive feat, to be sure, but it’s just the beginning, for it’s off in the distance that the final theory resides. It’s surrounded by clouds that hide mysteries that we’ve yet to uncover. Maybe in our exploration, we’ll discover a hidden valley filled with magical creatures that we’ve never imagined.

Science popularizations are entirely misleading on where we are in this effort. This isn’t to minimize our accomplishments; we’ve come a long way. But we have even further to go. This is a journey of the ages, and maybe our great-great-great-great-grandchildren will find the final answer.

Common Questions About the Time Frame for a Theory of Everything

Q. How much time did it take to go from the idea of atoms to the idea of quarks?

The original idea of atoms arose with ancient Greek philosopher Democritus, a couple of hundred years BC. But it took something like 200 years to go from a fairly firm proposal of chemical atoms in the 1770s or so, to the observation of quarks in the 1970s.

Q. How much time did it take to reach the idea of the fundamental forces we now know?

Newton unified gravity in 1670, while Maxwell’s unification of electromagnetism was in about 1870. There was a more recent unification of electromagnetism and the weak nuclear force in about 1970. So, it took about 300 years to arrive where we are now.

Q. What is a Grand Unified Theory (GUT)?

A Grand Unified Theory is a theory which would be able to unify the Electroweak and the Strong forces into one single force.

Q. What is the energy barrier that current technology faces in unifying the forces?

Fundamental physics theories span a huge amount of energies. The energies we explore at the frontier of knowledge are about 10 trillion times higher than the energies of chemistry. But the energy at which we kind of think that gravity unifies with the other forces is a quadrillion times higher than what we can achieve with today’s technology.

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