Chapter 23
What is an Observer?

This topic forms the very crux of why many people think quantum physics is completely different to classical physics. A similar question we just asked is: “What is a measurement?” for this is exactly what an observer does. They must observe in some way such that a result of the experiment or event may be known or realised – turned from potential to actual. Physics could not progress or be useful without getting real outcomes that can be compared against theoretical predictions. This is why science is trustworthy and factual. Despite being a kind of art in some ways it is not fiction.

It is this critical testing performed independently that helps keep science truthful.

We need to perform observations to both provide data that is used to help formulate theories or new ideas and secondly enable others to confirm or deny the reality of these theories using additional experimentation.

It was usual in the past for the same person to perform both functions, but today it is not very common, and physics is broadly divided into two branches called experimentation and theoretical physics due to the work and complexity involved in each.

When we consider what light is and how it behaves, we must be aware of the fact that it is made from tiny individual photons or particles that are emitted from the single source one by one and similarly absorbed by a single receiver one by one. Usually the source and receiver are both separate electrons. All light does this no matter how bright it appears. Light can be bright or dim depending on the number of electrons emitting photons from the source. Brightness simply means many more photons that are travelling together, although often in different directions and energies and with different phases or positions of the E-M fields within their individual sinusoidal cycles. Light photons have different colours due to the different energies they are carrying in their vibrations. Pure single coloured or monochromatic light is rare and only possible in lasers.

The emission and absorption of light can appear to behave differently depending on its brightness or the number of photons involved. In other words one or many. In our everyday world light usually consists of billions of photons that make what we call a beam and has properties such as a spherical wavefront, different colours, different polarisations and the ability to follow an apparently single defined path. It can also be observed without causing it to be affected by the observation, provided the experiment is designed to do this.

This is not the case for an individual photon We therefore need to ask: For a single photon before and after it is observed, was the E-M wave we perceive originally a kind of potential sphere that somehow disappears everywhere except the point in space where it interacts and is observed to be? Or is it always a straight line that connects the source directly with the receiver?

A very large number of photons leaving a bright light source make a spherical wave like the light we observe from the sun and stars. It travels in all directions simultaneously. But what about a single photon? Is this somehow also able to travel in all possible paths before reaching its destination? This is something Feynman and others seriously considered in the subject of quantum electrodynamics, or QED.

Referring back to Schrodinger and his equation: Is this what is meant by the collapse of the wave function once an observation is made? The potential sphere becoming a single straight line? Not a real line but only the path it must have travelled in going from source to receiver. Somehow the wave has the potential to spread everywhere over the sphere’s surface, but once it interacts with something at some point this potential disappears instantly in all other locations no matter how far apart they are. Is this how entanglement works in particles such as pairs of electrons that can be widely separated but be observed to have opposite states and thus giving rise to a loss of locality as found in the EPR paradox?

Is this what happens when a photon reaches its receiver and is absorbed? For light particles we then say the photon moved from A to B at light speed but where else has it been if at all?

Some may say this is purely a quantum phenomenon and not something classical physics should ever be concerned with. SED disagrees and asks: Whynot? Surely this whole scenario is being described using conventional arguments and ideas many scientifically inclined readers could follow. It is at the very heart of how science progresses.

The Origin of Everything
(Online Edition)