TITLE: What defines a physical property?
QUESTION [2 upvotes]: The physical world around us has all sorts of properties, shape, color etc. If you move on to more complex systems, there are even more like some emotional properties etc. 
Why do we deem only certain of them as physical like mass, length, time etc. and not others?

REPLY [4 votes]: This is, as you stated in the title of the question, a problem of definition. 
In order to be useful for Physics (and most Science), there is a key characteristic of the properties we use: they have to be objectively measurable. As dmckee stated in a comment to the question, the property does not only need to be able to be put in scale (as you said, you could make a scale of love), that alone is not useful for Physics. You have to be able to make a objective scale reproducible by anyone (for example, you could measure the activity in the brain area responsible of affection, but not love itself, as it differ with the person). That does not mean that you can't do Science with other properties, it just mean that they are not useful with methodology in Physics.
This is why some scales as the dol scale for pain don't measure physical properties, it depends on the person. They might be useful in other areas.
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