A great challenge within physics today is understanding how the same physics is able to operate at different scales. The geometry of planets and galaxies seems to operate in the same way as the physics of airplanes and softballs, but dive a level deeper and the physics of electrons and photos does not quite seem to follow the same rules. Experiments give us photons that seem to know how we are looking at them, and behave differently depending on what experiment we choose and what method of observation we use. Once we get to the super small world of particle physics, we continue to use the same physics, but the interactions between matter and energy seems to be different. Piecing together exactly what is happening is challenging, and often requires looking at the results of experiments in new and creative ways.
In her book Trespassing on Einstein’s Lawn, author Amanda Gefter explores many of these head turning and confusing realities. She looks at the smallest scale we can reach in the universe, the point at which there simply are not more “things” to be discovered by looking for even smaller and smaller particles. At the Plank scale, gravity and energy have interactions that we would not expect based on our understandings of quantum physics. Gefter describes what physicists observe,
“But keep zooming in and, strangely, things start to turn around. The laws of quantum mechanics contain a loophole that allows large fluctuations of energy to burst forth from the vacuum, provided they don’t stick around too long. At increasingly shorter time scales, energy blinks in and out of existence in the form of fleeting, or ‘virtual,’ particles. The more localized the virtual particle, the greater its momentum, and the greater its momentum, the larger its energy. Thanks to E=mc2, more energy means more mass. So as you look at smaller and smaller distances, virtual particles grow increasingly massive until, at the Plank scale, gravity grows as powerful as the other forces An energy in its own right, gravity’s crescendo generates a runaway feedback disaster of the same variety that can collapse a 1032 pound star into a black hole.”
Gefter describes the process above as the breaking of spacetime and refers to John Wheeler who said that this process creates “spacetime foam.” Physicists are challenged because all the forces we experience as sentient human beings exist across all scales, but their impact is different based on the mass and energy of the particle or system. Gefter’s quote above shows us that physics does not just go away at a certain point. Instead, the rules remain, but the way the rules play out changes.