What is engineering and what is experimental design?

Question

So we have a close reason for engineering questions because selection of materials for building that ultralight in the garage are off-topic. But where is the line drawn between engineering and experimental design? The question I'm thinking of specifically is:

Pressure applied to flat plate

Without any context, the asker could be designing a vacuum cleaner and this would be off-topic as an engineering question. Or OP could be setting up a shock-tube experiment, or a low-pressure chamber to study some particles or something, in which case it would be on-topic as an experimental design question.

So without any context, how does one draw the line? Even with context, does the engineering close reason indicate we no longer want questions about building experiments?

Answer 1

Hm... after thinking about it, this is rather complicated.

Here's a rule of thumb that might work: physics experiments generally involve some sort of extreme condition that makes normal, everyday materials or building techniques unsuitable. If the question identifies a specific requirement of that type, and displays prior research showing that the OP has verified that normal materials are unsuitable, it should be fine, because the properties of materials under extreme conditions is within the domain of physics.

Also, questions about what materials or building techniques are commonly used in physics experiments, even the more ordinary ones, are fine. In this case the question would have to identify that it is actually about a physics experiment. For example, "what are muon scintillators normally filled with?" would be okay.

Questions which ask how to calculate properties of a material, like the one you linked, are also fine. But the key here is that the question needs to ask how to do the calculation, not just "calculate this for me," for the same reason we don't allow no-effort homework questions.

Answer 2

I also think it is valuable to have some place that sometimes posts 'real-life' examples of work physicists are doing outside of academic physics. For example, medical physics, aeronautics, and computer science - which may actually be engineering problems - but may employ more persons that have physics degrees than universities. There are likely students that read here that know better than to flat-out ask "What can I do with a degree in Physics?" but that are very interested in formulating an answer to that.

So a second criterion for including or closing an 'engineering' question might be whether the contribution of a trained physicist is likely necessary for its solution in a real-life situation.