We all assume that there is an objective reality out there, independent of our perception and observation. But what if that assumption is wrong? What if reality is actually created by our interactions with it?
This is the radical idea that some physicists are exploring, based on the findings of quantum mechanics. Quantum mechanics is the branch of physics that deals with the smallest particles and forces in nature.
It reveals a bizarre world where particles can exist in superpositions of two or more states at once, until they are measured and collapse into one definite state. It also shows that particles can be entangled, meaning that their states are linked even when they are far apart, and that measuring one affects the other instantaneously.
These phenomena defy our common sense and challenge our notions of reality. They suggest that reality is not fixed and objective, but rather dependent on how we observe it. Some physicists have even proposed that reality does not exist until it is observed, and that observation creates reality.
One way to test this idea is to perform a quantum experiment with two observers who have different information about the system. For example, one observer could know which slit a photon passes through in a double-slit experiment, while the other observer could only know where the photon lands on a screen.
According to quantum mechanics, the first observer would see the photon behave like a particle, while the second observer would see it behave like a wave.
But what if both observers could communicate and compare their results? Would they agree on what happened? Or would they see different realities? And if so, which one would be true?
This is essentially what a team of physicists from Heriot-Watt University in Edinburgh did in 2019. They performed an experiment where two observers measured the polarization of photons entangled with another pair of photons.
The first observer had access to both pairs of photons, while the second observer only had access to one pair. The first observer could choose to measure either pair or both pairs simultaneously, while the second observer always measured one pair.
The results showed that when the first observer measured both pairs simultaneously, he saw them as entangled and correlated. But when he measured only one pair, he saw them as independent and random. The second observer always saw them as independent and random.
This means that when both observers compared their results later on, they would disagree on what happened. The first observer would say that he saw entanglement between both pairs of photons at some point in time, while the second observer would say that he never saw any entanglement at all.
The researchers concluded that this shows that “the facts of the world can change depending on how you look at it”. They argued that there is no objective reality out there waiting to be discovered; rather reality emerges from our observations and interactions.
This idea has profound implications for our understanding of nature and ourselves. It suggests that we are not passive spectators of reality; we are active participants who shape it with our choices and actions.
It also raises questions about how we can communicate and agree on what is real; how we can trust our senses and measurements; how we can reconcile different perspectives; how we can define truth; how we can explain causality; how we can avoid paradoxes; etc.
Of course, this idea is not without its critics and challenges. Some physicists argue that there are alternative interpretations of quantum mechanics that do not require such a radical revision of reality; such as hidden variables theories or many-worlds theories.
Others point out that quantum effects are only noticeable at very small scales; whereas at larger scales classical physics still applies and gives us consistent predictions about objective facts.
However, some recent experiments have shown signs of quantum effects at larger scales; such as superposition states in molecules or interference patterns in buckyballs (soccer-ball shaped molecules). This suggests that quantum mechanics may apply to all levels of reality; not just microscopic ones.
If this is true then objective reality may indeed be an illusion; or at least an incomplete picture of what really exists.
