Quantum physics: Certainty kills the probabilities

Quantum physics is the study of things that are very, very small, like atoms and smaller. It's a fascinating field of science, but also very strange and mysterious.

Why is it strange and mysterious?

One of the reasons is that quantum physics deals with probabilities, not certainties. That means that we can never be sure about the exact state or behavior of a quantum object, like an electron or a photon. We can only predict the likelihood of finding it in a certain place or doing a certain thing. It's because quantum objects are both particles and waves at the same time. This means that they can act like tiny bits of matter, but also like ripples of energy. Depending on how we observe them, they can show either aspect. But we can never observe both aspects at once.

What happens when we observe them?

That's where the phrase "certainty kills the probabilities" comes in. When we observe a quantum object, we force it to choose one aspect and one outcome out of many possible ones. This is called the collapse of the wave function. For example, if we measure the position of an electron, we will find it in one specific spot. But before we measure it, it could have been anywhere in a cloud of probabilities. Observation affects reality at the quantum level. This is one of the most puzzling and profound implications of quantum physics. Some scientists even think that this means that consciousness plays a role in creating reality.

We use experiments and mathematics to test our theories and predictions. One of the most famous experiments in quantum physics is the double-slit experiment. It shows how light behaves like both a particle and a wave, depending on how we observe it. It also shows how light can interfere with itself, creating patterns of light and dark on a screen.

Imagine you have a source of light, like a laser, and two slits in a barrier. If you shine the light through the slits, you will see a pattern on a screen behind the barrier. If light was only a particle, you would expect to see two bright spots on the screen, corresponding to the slits. But if light was only a wave, you would expect to see a series of bright and dark bands on the screen, corresponding to the interference of the waves. But what actually happens is that you see both effects at once: an interference pattern with two bright spots in the middle. This means that light is both a particle and a wave.

But what if you try to observe which slit each photon goes through?

That's where things get even more amazing. If you try to observe which slit each photon goes through, you will find that the interference pattern disappears and you only see two bright spots on the screen. This means that by observing which slit each photon goes through, you force it to act like a particle and not like a wave. You kill the probabilities and create certainty.

How can observation change reality like that?

That's one of the biggest questions in quantum physics. There are many interpretations and explanations for this phenomenon, but none of them are fully satisfactory or universally accepted. Some say that observation creates reality by collapsing the wave function into one outcome out of many possibilities. Some say that observation reveals reality by selecting one branch out of many parallel realities. Some say that observation entangles reality by creating correlations between different systems. And some say that observation does not affect reality at all, but only our knowledge of it.