I agree that questions about building experiments, if specific to our subject, should be allowed.

That is, until they are about physics. A question about "what type of concrete should I use to build my atom smasher" is not about physics.

The key point here is this.

Questions that work are questions:

• which are best asked to a physicist (an experimental physicist in this case, but not a engineer or a mathematician)

• whose answers are best judged by a physicist

If we fail to realise this and stick to it the obvious consequences are going to be poor answers and bad answers being voted. Furthermore it will be unlikely to self correct because it requires competence to determine poor answers (e.g. If someone answers with the wrong kind of concrete, to the example above, who would know better?)

That said, that particular question is poor on many levels.

I agree that questions about building experiments, if specific to our subject, should be allowed.

That is, until they are about physics. A question about "what type of concrete should I use to build my atom smasher" is not about physics.

The key point here is this.

Questions that work are questions:

• which are best asked to a physicist (an experimental physicist in this case, but not a engineer or a mathematician)

• whose answers are best judged by a physicist

If we fail to stick to this (obvious) principle, the consequences are going to be poor answers being given and bad answers being up voted. 

Furthermore the problem will struggle to self correct because it requires competence to determine poor answers. If someone answers with the wrong kind of concrete, to the example above, who would know better, or that we have a problem at all?

That said, that particular question is poor on many levels.