medium sizeModern physics involves some truly mind-boggling extreme scales. Cosmology reveals that the Earth is a tiny dot in the observable universe, with a staggering 93 billion light-years in diameter. Meanwhile, today’s particle colliders are exploring microscopic worlds billions of times smaller than the smallest atoms.
These two extremes, the maximum and minimum distances scientifically detected, differ by 47 orders of magnitude. That’s a number followed by 47 zeros, a number so ridiculously large that it’s not even worth thinking about. Yet despite exploring such distinct distances and phenomena, cosmology and particle physics remain closely linked. Observing the motions of stars and galaxies can reveal the influence of yet-to-be-discovered particles, while studying elementary particles in the laboratory can tell us about the birth and evolution of the universe.
Interestingly, both disciplines grapple with unexplained results that may indicate the existence of a new force of nature. If this new power is confirmed, it will have profound consequences for our understanding of the universe, its history and composition.
We already know that there are four forces. Gravity controls the grandest scales, aligning planets in their orbits and shaping the evolution of the entire universe. The electromagnetic force generates a wide range of phenomena, from the Earth’s magnetic field to radio waves, visible light and X-rays, while also binding atoms, molecules and the physical world together. Deep within the nucleus, two other forces arise: a vise-like strong force that binds the nucleus, and a weak force that causes radioactive decay and triggers the nuclear reactions that power the sun and stars.
Studying these forces has transformed our understanding of nature and led to revolutionary new technologies. The study of electromagnetism in the 19th century gave us electric generators and radio broadcasts, the discovery of the strong and weak forces in the 1930s led to nuclear energy and the atomic bomb, and an understanding of gravity allowed us to put astronauts on the moon and Space travelling. Discovering the fifth power would be a huge reward.
Over the past decade, there have been growing signs that physicists may be on the verge of such a breakthrough. The first evidence comes from particle physics experiments on Earth, the results of which appear to conflict with our best current theory of elementary particles, the Standard Model.
Despite its rather bland name, the Standard Model is one of humanity’s greatest intellectual achievements, the closest we have to a theory of everything, and it passes nearly every experimental test with flying colors. At least so far.
However, the BaBar experiment in California, the Belle experiment in Japan, and the LHCb experiment at CERN have all discovered exotic elementary particles called beauty quarks that behave in the opposite way to the predictions of the Standard Model. Meanwhile, just outside Chicago, Fermilab’s Muon g2 experiment has been busy studying another elementary particle called a muon, finding that it emits a slightly stronger magnetic field than expected.
The most exciting explanations for these anomalies involve hitherto unknown natural forces that subtly alter the way beauty quarks transform into other particles or disrupt muon magnetism. This new power could help unlock the deeper structures underlying reality, explaining why we have the elementary particles we do in nature. Another tantalizing possibility is that it could serve as a link to an invisible dark universe made of invisible dark matter.
Still, the overall picture remains frustratingly unclear. Just over a year ago, new results from the LHCb poured cold water on prospects for a major breakthrough, after omission bias was discovered in some early measurements. Meanwhile, theorists have been debating how magnetic muons should be, and the anomaly could be caused by computational problems.
Perhaps the most compelling evidence for new forces in the universe comes from the other end of the cosmic scale. Over the past few years, cosmology has been divided by the so-called Hubble Crisis, a huge disagreement over the rate at which the universe is expanding.
According to the accepted cosmological story, the universe as we know it began with the Big Bang about 13.8 billion years ago and has been expanding ever since, with galaxies getting further apart as the space between them stretches. Cosmologists have two ways to calculate how fast space is stretching. One involves studying many distant galaxies through telescopes and then determining the relationship between their distances and how fast they are moving away from us. Another approach is to use precise maps of the faded light from the Big Bang fireball, known as the cosmic microwave background, to infer the properties of the infant universe.Then you apply the current cosmology to run the clock and predict How fast the universe should be expanding today.
The fact that these two methods give different answers is the strongest evidence we have that there is more to the universe than we have thought so far. The possibilities are many. One popular proposal involves a form of energy that drove the universe to expand faster than thought shortly after the Big Bang. Others involve dark forces operating in the hidden world of dark matter. Some have even suggested that gravity itself behaves differently in the vast spaces between galaxies.
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How the story of these anomalies will end is unclear. But a wealth of emerging evidence does suggest that physics may be on the verge of something big. The discovery of a new power would mark the beginning of a new era of exploration, perhaps providing a deeper understanding of the fundamental building blocks of nature or opening the door to a vast, unknown, albeit unseen, realm of darkness , but it contains 95% of natural forces. These breakthroughs never come easy, but following nature’s lead may soon lead to profound new views of the universe.
Harry Cliff is the author of Space Oddities: Mysterious anomalies that challenge our understanding of the universe (Picardo).
further reading:
White Hole: Within the Horizon, Carlo Rovelli (Alan Lane, 14.99)
The End of It All: (Astrophysically speaking) Katie Mack (Penguin, 10.99)
Elephants in the Universe: Our Centennial Quest for Dark Matter by Govert Schilling (Belnap, 24.95)
#overriding #thought #discover #force #nature
Image Source : www.theguardian.com