Physicists hint at a ‘fifth force of nature’

May the force be with you: The fundamental forces affect everything that we can observe.

Scientists around the world are abuzz with news of a study which suggests there could be a ‘fifth force of nature’. It would revolutionise our knowledge of the universe. But would we notice?

When Isaac Newton published the Principia in 1687, it completely changed the way people understood the universe. We had trusted Aristotle’s theory that the universe works the way it does because everything has a ‘natural place’. Or rather, it is the way it is because it is.

Newton turned that on its head: the force which he called gravity did not just bring apples from the branches of trees; it held the entire universe together, kept the Earth spinning around the sun, and kept the moon circling the Earth. He had essentially invented modern physics.

Now scientists teach that the universe is governed by four ‘fundamental forces’. The first is gravity. The second is electromagnetism, which keeps molecules together. The strong nuclear force is the ‘glue’ which binds the nucleus. The weak nuclear force is responsible for the atomic decay which causes radiation. Together, they are a key part of the ‘standard model’ of physics which elegantly explains everything that we can see.

But in recent years, that model has felt increasingly incomplete. Around 80% of the universe is made up of ‘dark matter’, something that physicists cannot see, because it does not obey the laws of electromagnetism. So some have been searching for a fifth force which could explain it.

This is what motivated scientists in Hungary last year when they fired photons at a lithium-7 isotope. In the fallout, they observed some bizarre behaviour which could be explained by a new, totally unexpected particle.

When scientists in the USA examined their results, they said that this particle could be related to a fifth fundamental force. If that is true, it would open up a brand new, unexplored realm of physics.

Other physicists are sceptical, but intrigued. And several teams are now excitedly planning to recreate the experiment to test its results, including a team at CERN. Nothing is confirmed, they say. But it is certainly possible that ‘we are seeing our first glimpse into physics beyond the visible universe.’

Small matters

‘Who cares?’ shrug some. The kind of science we are talking about is so infinitesimally tiny that we literally did not notice it until now. Even if theories about a new force turn out to be correct, it is difficult to understand how the discovery could change ordinary lives.

True, admit scientists. But that is what makes the idea so exciting. Humanity survived before we understood gravity, but now we have learned how to fly. We did not need to know about electricity, but now we cannot imagine life without it. We were happy enough with four fundamental forces — but a fifth brings previously unimaginable possibilities. Now we have the pleasure of imagining them.

You Decide

  1. Will knowing about a fifth force of nature — if it is true — change your life?
  2. There is so much that scientists don’t know about the universe. Is that scary or exciting?

Activities

  1. Draw a diagram which explains the particles of an atom, in as much detail as you can.
  2. The most common way of explaining gravity is by telling the (possibly exaggerated) story of the apple falling on Isaac Newton’s head. Write three more allegorical stories which explain the other fundamental forces.

Some People Say...

“Plato is my friend, Aristotle is my friend, but my best friend is truth.”

Isaac Newton

What do you think?

Q & A

I’m confused. Does it exist or not?
We don’t know yet. But the scientists in Hungary tested their results for three years before publishing to eliminate any errors, and they say the results which started it all have a ‘one in 200 billion chance’ of being a fluke — so they are pretty confident. However, it will take at least a year for other scientists to recreate the experiment and draw their own conclusions.
And if they get the same results?
It will be a fairly big deal, and they will try to pin down a more concrete explanation. If that is a fifth force, or if it is related to dark matter, it would be huge. Remember, the standard model of physics only accounts for the things we can observe, which is just 20% of the universe. Moving beyond that would represent a whole new era of discovery.

Word Watch

Principia
The three books of Philosophiæ Naturalis Principia Mathematica lay out the laws of motion, which inspired mechanics. Tim Peake’s International Space Station mission is named ‘Principia’ in its honour.
Hungary
The Hungarian Academy of Science published their result in 2015, largely unnoticed until US scientists wrote their own report on the findings.
Lithium-7 isotope
A form of the soft metal lithium, the third chemical element in the periodic table.
Bizarre behaviour
Much current physics involves recording what happens when particles are slammed into each other. In this case, the lithium produced unstable beryllium nuclei which decayed into electron-positron pairs that ‘flew away from each other at various angles’, with 140 degrees unexpectedly common; this ‘bump’ in the results could be the result of a tiny new particle.
CERN
Home of the Large Hadron Collider. CERN (French acronym: Conseil Européen pour la Recherche Nucléaire; or European Council for Nuclear Research) discovered the Higgs boson in 2012, supposedly the final ‘missing piece’ of the standard model of physics.

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