Definitive measurement that determines state of matter?

[curiousoldguy]

What is an (the?) empirically demonstrable method used for determining a substance's state of matter?

If a new substance was discovered and scientist A said it's solid and scientist B said it's a liquid, how would it be demonstrably proven to be one or the other? The books I have define states of matter in scientifically unsatisfying terms like "if there is very little room between molecules but they can move it's a liquid": it doesn't seem testable: my definition of "very little room" might be different than yours. For example, is there a magic heat capacity that for any substance, if it's above 25 J/C it's by definition a solid? I can look-up tables of characteristics for known substances, but what about one that falls from outer space we know nothing about?

Thanks for any insight. :)

 

[jbriggs444]

If you can pour it into a cup, it is a liquid. If you can build a bridge from it, it is a solid.

Seriously though, the line between solid and liquid is not always well defined. http://www.nature.com/news/world-s-slowest-moving-drop-caught-on-camera-at-last-1.13418

 

[Dale]

A substance's state of matter is just a rough characterization. Real physical systems are not always so clearly distinct to where they can be classified. For example, at the critical point and beyond the liquid and gas phases are not distinct.

 

[Bystander]

See/Google "non-Newtonian fluids."

 

[curiousoldguy]

Thanks. I got the feeling they were general terms. :)