Reduce gravity

1 Gravity is fun!

The word gravity is derived from Latin by Newton solemn, conveying weight and deadly seriousness. But gravity may work against that. As I researched my book during sleep-deprived days during the pandemic, the role gravity played in some of my most memorable moments kept flashing back to me: swinging in a hammock in the Amazon, learning to fly over Niagara Falls , or just let yourself fall into the arms of your loved ones. I slowly began to understand why my colleagues and I had put so much effort into unraveling our theory of large gravity.

Technically, the theory we discovered is a model in which gravitons (particles that mediate gravity) have mass. Its description of gravity goes beyond Einstein’s general theory of relativity and attempts to solve some of the most challenging problems we currently face in theoretical physics at the interface between cosmology and particle physics. But whereas Einstein’s theory had infinite scope and was rigid and inflexible, our theory is inherently finite: it closes and lets go at a certain point. This is Einstein’s theory with a sense of humor: Sometimes it really matters, but underneath the right circumstances lies the ability to relax and have a little fun.

2 Simple can be confusingly complex

E=mc² There is no denying that this is the most famous formula in the world. It shows that energy is equal to mass times the speed of light squared, and that under the right conditions energy and mass are equal. We take it for granted every day as we enjoy the light and warmth of the sun, which produces energy by releasing 4.7 million tons of mass every second. By now I’m sure most people living on this planet will have seen this formula in a book or on a t-shirt. However, explaining what these concepts mean in practice can be more challenging than explaining some of the more seemingly technical and obscure equations I’m used to dealing with. This equation is also probably one of the most misunderstood.

3 The speed of darkness sometimes exceeds the speed of light

I love explaining physics concepts to children or those who are young at heart because they see it all and get right to the point. I’ve tried many times to talk about the speed of light, but am always interrupted within seconds, and I’m asked to compare it to the speed of darkness before the conversation quickly and confusingly flows into a black hole, the end of the world.

The universe is indeed dark, or at least dark to us, and filled with what we call dark energy, a fluid-like element that drives the accelerating expansion of the universe. Under certain circumstances, this dark energy can also propagate waves at a finite speed. Interestingly, the speed of these dark waves may in some cases be faster than the speed of light itself.

If our universe were flat and unchanging (flat spacetime), then faster-than-light travel would be strictly prohibited. But our universe is much more interesting. It evolves over time and carries the curvature of space and time, supported by gravity, in ways that can make the seemingly impossible possible, beyond our wildest imaginations.

Main image: cybermagician/Shutterstock

• Claudia de Lam

  Published on April 25, 2024

  Claudia de Rham is a theoretical physicist at Imperial College London. Her research in the fields of gravity, cosmology and particle physics earned her the 2020 Blavatnik Young Scientist Award. The Beauty of Falling: A Life Pursuing Gravity It tells the fascinating personal story of de Rams’s quest to get intimate with gravity and understand its feel and fundamental nature. She is an active activist against the underrepresentation of women in physics.

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