A technician explains measurements whilst a scientist explains observations.

The use of the word "illusion" when discussing time and consciousness.

Illusions are experiences that do not correspond to events in the world beyond the nervous system.

In philosophy and neuroscience the word "illusion" is often used incorrectly to dismiss the apparently inexplicable. Here is an example:

"Our sense of now can be viewed as a psychological illusion based on the past and a prediction of the near future" David Melcher, quoted in New Scientist 10/1/2015

There is no "illusion" in the experience of events over a short period of time if these events occurred in the world outside the brain in the sequence in which they were observed. In fact all events are perceived over a period of time, as an example, this text must be viewed for much more than a nanosecond and persist in our experience for much more than a nanosecond to become part of our experience. Either the word "illusion" is being reserved by Melcher to describe events that change over time or he is describing all experience as an illusion and this is self evidently contrary to the definition of the word "illusion".

Why do some authors use the word "illusion" when discussing changing events? It is because there is a fallacious argument about experience containing temporal extension that is widely accepted. This argument says that:

 "Can we perceive a relation between two events without also perceiving the events themselves? If not, then it seems we perceive both events as present, in which case we must perceive them as simultaneous, and so not as successive after all." Stanford Encyclopedia of Philosophy. The Experience and Perception of Time.

The argument is a fallacy because it relies on the Alexandrian notion of time, not modern space time geometry. Our experience contains temporally extended events in the same way as it contains spatially extended events: they are projected from a virtual geometric point. If you do not believe me just look at this page. If you are interested in spatio-temporal projection (experience) then read the articles on this website.

It has been found that nearly all illusions seem to involve events in the brain that correspond to the illusory experience - in the same way as all sensory events that find their way into experience involve events in the brain. In this sense all illusions are real.  The profound mystery is how the events form the spatio-temporal projection called "conscious experience".