I've been in a number of physics discussions where the word "illusion" has come up (sometimes brought-up by me). I like it, but others seem not to.
Here's the definition from a google: "a thing that is or is likely to be wrongly perceived or interpreted by the senses."
My perception is that people dislike the word because they think it implies that what you are seeing isn't real. The way I read it, the definition doesn't say that. It says the interpretation is wrong.
In physics, scenarios where people see different things come up all the time when transforming reference frames and, in particular, when using rotating frames. It also happens if you consider a stream of photons (or water from a hose) as a solid object instead of individual elements that move separtely from each other.
Now, perhaps people don't like it because the definition contains the word "wrong". Different views of events from different reference frames are all equally valid, so one can't be "wrong". But that's not the way an illusion makes you think something wrong. Many optical illusions (perspective tricks) are, reference frame transformations. What makes the perception "wrong" is that you draw a wrong conclusion about what you would see from a different reference frame based on what you are seeing from the provided view. Sometimes the wrong conclusion is even the very idea that only one view of the events is valid.
So, I'd like some feedback: Does my explanation make sense? Is it a wrong/non-standard interpertation? Even if correct, does a connotation on the word make you prefer to avoid it? Or, even if correct, does it often get misinterpreted by laypeople and thus you prefer to avoid it?
That last bit is may be the key. The place where this came up recently was in a thread where we were trying to explain an issue of (Newtonian) relativity to someone. On PF, as everywhere, it is difficult to know how to explain something to a layperson in order to be accurate but not so complicated as to be confusing. This is why things get "dumbed-down" in lower level classes in school. Why you learn a different version of Conservation of Mass and Conservation of Energy from what you'd learn later on, for example. Or why no one tells you at first that Newtonian physics isn't always correct. Same issue goes for analogies. An analogy can be useful - and I like them - but if a person reads into them something that isn't intended/goes past what was intended, it can lead to a wrong understanding.
Those issues are difficult, but ultimately I think the best explanation is the one that provides the student with the correct understanding with the least amount of effort. And that can vary from one student to the next. So we shouldn't need to argue about which is better because it isn't up to us (the teachers): which is better is not always the same and is up to the student to decide. The best explanation is the one that speaks to the student best.
[mod hat: part of my reason for starting this thread was so I had a place to move a discussion to keep it from dragging a thread off-topic. The next few posts are from that thread.]
[edit] Hmm...Interesting...posts are always in chronological order. Oh well...
