Physics is all around us, taking place within our coffee mug, within jet airplane engines, and on the roof above our head. Everywhere we go, physics goes, and everywhere we look, we see physics. Across the universe, magnified at the end of an electron microscope, and throughout time, physics connects everything there is. Amanda Gefter in her book, Trespassing on Einstein’s Lawn, describes the importance of viewing physics within a totally inclusive system. Because we are walking physics experiments, we alter the physics of the world around us and have an impact on every system that we study and interact with. In fact, it is not just us but everything that interacts or has the ability to observe a phenomenon in physics that acts upon and changes the system.
This is important because it shapes the way we study and understand physics and reality. There is no way for us, or anyone or anything else, to stand outside the universe and look back in at the universe to make an observation independently. If you are observing the universe you are within the universe and you are part of the universe. Describing her efforts to learn and understand what this means for physics, Gefter wrote,
“I had already learned that both relativity and quantum mechanics were trying to tell us the same thing: we run into trouble when we try to describe physics from an impossible God’s-eye view, a view from nowhere. We have to specify a reference frame, an observer. But now I finally understood the real tension between the two theories. The whole mess could be summed up with one question: where’s the observer?”
General relativity tells us that everything is inside the universe, but when we look at quantum mechanics we are trying to look at incredibly tiny particles that form the building blocks of the universe. A tension arises because we appear to be able to separate ourselves from the system in which our experiments take place, but the reality is that we are making an observation of the system, which means we are interacting with the system. Even when we take the human part away from our experiments and our systems, we still leave behind something to make an observation to somehow detect what is taking place. An observer does not have to be conscious and is better thought of as a frame of reference or something that can be changed and adjusted within the system. The only way we could truly understand pure physics it seems, is to be completely outside the system to look in and observe without changing the system, but this completely violates what we know is possible about how our universe works.
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.