# There are 3 things not made of matter [closed]

When I'm teaching middle school science and I'm teaching the concept of matter I usually tell them that everything is made of matter except for 3 things.

Space-Time, Energy (light, heat, kinetic, potential, etc) and Abstractions (happiness, love, running, numbers, etc)

Although Space-Time is not on the syllabus the students love to hear anything that follow ''this is not on the syllabus but ...''

Is this a fair statement or am I leaving something out?

• What does it mean exactly? One could argue that energy is an abstraction, or that happiness is made of matter (as a state of the brain). I don't think this question actually has a physics content, it's about general education, language or philosophy. – fqq Nov 16 '19 at 19:00
• I recommend sticking with examples of what is made of matter: our bodies; the air; planets and stars, etc. And contrasting this with vacuum, such as outer space. – G. Smith Nov 16 '19 at 19:03
• Making examples without defining what you mean by matter is meaningless. – GiorgioP Nov 16 '19 at 20:52
• If you say that light is not matter, do you say anything about how do we know it? – GiorgioP Nov 16 '19 at 20:55
• With this definition, you are left with abstractions only, since taking space is not applicable to space-time and a box with light inside does have energy ( $E=mc^2$). Energy in turn is a property of a physical system, it is not itself a physical system. In any case your students cannot check experimentally your claims about the mass, so you are asking them to trust you, instead of explaining them "how do we know that...". – GiorgioP Nov 17 '19 at 8:58