Are You Certain? The Relationship between Physics and Philosophy

“What we observe is not nature itself, but nature exposed to our method of questioning”

This quote by Werner Heisenberg reflects the deep interplay between physics and philosophy, a relationship that is often overlooked. To the untrained eye, physics and philosophy could appear to be opposite ends of the academic spectrum, two unrelated subjects, one of which deals with facts through numbers, and the other of which deals with questions through words. However, this “academic spectrum”, quickly appears more cyclical than linear when we realise physics was historically known as ‘experimental philosophy’, blurring the boundary between the two fields. Indeed uncertainty itself becomes the bridge that connects them, an idea made famous by Werner Heisenberg.

Heisenberg, a founding father of quantum mechanics, was a German physicist, and some may say philosopher, born in 1901. At just 31, he was awarded the Nobel Prize in Physics for his development of the Uncertainty Principle. Simply put, this principle states that there is a fundamental limit to how precisely we can know certain pairs of physical properties at the same time. One of the most common examples involves position and momentum; you cannot know both the exact position and momentum of a particle at the same time. This is not a flaw of our measuring devices but rather a fundamental property of nature. Heisenberg showed that, on quantum scales, particles don’t have definite positions and momenta until they are observed.

The philosophical implications of this were groundbreaking. Before quantum mechanics, many scientists, including Einstein, believed in determinism, the idea that if you knew everything about a system, you could predict everything about its future. However Heisenberg’s principle shattered this view as it suggested that the universe has built-in limits of knowledge, that some things cannot be known with absolute certainty. Heisenberg admitted that he could not have come to this conclusion with physics alone, stating ‘after the conversations about Indian philosophy, some of the ideas of Quantum Physics that had seemed so crazy suddenly made much more sense.” Heisenberg’s willingness to explore physics through the lens of philosophy contributed to the creation of the new field of quantum physics, showing the importance of an interdisciplinary approach.

Heisenberg’s realisation didn’t just change physics, it also reshaped philosophy and epistemology (the study of knowledge), sparking debates about determinism and free will. Returning to his earlier quote about observing nature through our questioning, Heisenberg implied that the act of observing isn’t passive, something he discusses in his book ‘Physics and Philosophy’. This insight led to philosophical discussions about whether reality exists in a definite form when it’s not being observed, a debate which continues among physicists and philosophers alike today.

The interplay between physics and philosophy still plays an important role in the world today. The uncertainty principle remains at the heart of modern physics, influencing cutting-edge technologies like quantum computing and quantum cryptography. In an era where we try to predict and control everything from the stock market to climate change, Heisenberg’s work reminds us that some uncertainties are fundamental and perhaps even necessary. As physics continues to push the boundaries of knowledge, Heisenberg’s blend of science and philosophy remains a worldview that is as relevant and fascinating as ever.