Have Scientists Discovered a Fifth Force?

In physics, we know of four fundamental forces that explain our interactions with the world around us. Research may be getting us closer to naming one more. But what does all this mean?

The four fundamental forces

These are the four known forces of nature.

1. Gravity keeps our feet on the ground and our planet in orbit around our star. But while gravity operates over infinite distances—, and so governs the motions of black holes and entire galaxies—it is also by far the weakest of the four forces. 
2. The strong force holds atomic nuclei together. Just as its name suggests, it's ~10³⁸ times stronger than gravity—that’s 1 with 38 zeroes. However, it only operates, over a range of a femtometer, or about the size of one of those nuclei.
3. The weak force, which is still 1 million times stronger than gravity, is responsible for the radioactive decay of atoms.
4. The electromagnetic force governs the ability of charges to attract and repel each other. 

Each force is transmitted by a messenger particle, a type of elementary particle called a boson, that makes its presence known. For the electromagnetic force, this so-called force carrier particle is the light particle called the photon. Gluons are the force carrier particles that “glue” nuclei together via the strong force. The weak force has three known carrier particles called W and Z bosons. 

The Standard Model, or the theory that pulls all of these pieces together to explain how matter and the four fundamental forces interact, works well to explain much of our universe as we observe it. The theory has been rigorously tested and is supported by a multitude of observations, but there are still a few missing pieces needed to make this puzzle complete. For starters, the graviton, the carrier particle for gravity, is purely theoretical. So far, it hasn't been found. The Standard Model also doesn’t explain dark matter, the as-yet-undetected substance that makes up 27 percent of the universe.

Theorists have proposed additions to the Standard Model, like the existence of what they call “dark photons,”exotic particles that could act as carrier particles for a new force that affects only dark matter. These dark photons are what Dr. Attila Krasznahorkay at the Institute...

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