what is matter?

Answer 1

It's the stuff everything is made of.

Ask wiki.

edit: Be careful of anyone who tries to give you a more precise definition like "anything with mass." It is likely that no particle has inherent mass apart from the fields with which it interacts. Different physicists use different definitions in different circumstances, which means it's probably better to stick with a very general answer.

Answer 2

As you can see from the other answers, most of which are fine, you've asked a really difficult question to answer. I like to think, simplistically, that matter is anything that exhibits the characteristics of inertia. That is, matter is anything that requires a force to change its velocity because it has momentum (p = mv), a measure of inertia.

This, personal model, is consistent even when considering relativistic effects. For example, m = m0/L(v); where m0 is the rest mass (matter) and L(v) is the so-called Lorentz transform = sqrt(1 - (v/c)^2) where v = the velocity of that matter and c = light speed. If you play around with the value of v, you'll see that the effective m will increase with increasing v.

What is happening is that the inertia of that mass is increasing; so that, from p = mv, the momentum is also increasing with increasing v and m. This would not be the case for non matter without inertial characteristics. Notice that, because m depends on v and v is changing, both v and m in p = mv are changing. This means that momentum changes non linearly with changes in v.

Perhaps more than you wanted to hear, but you did ask a question that is hard to answer. And we haven't even gone into the Higgs Field model for matter. You might want to look that up on the web for some interesting reading about this WAG that some physicists subscribe to.

Answer 3

Matter is the substance of which physical objects are composed. It constitutes the observable universe. There is a tendency to regard manifestations of energy, such as light and sound, as not being material. However in physics the distinction is difficult to enforce — according to the theory of relativity matter and energy can be converted into one another.[1] Matter is said to have mass and to occupy space, but there are technical problems in physics with both criteria.

Dr. H

Answer 4

Experiments most firmly suggest perhaps defining matter as whatever produces and responds to gravity. Other claimed universal properties of matter like hardness maybe have less firm experimental support ?

Answer 5

Matter is anything which has mass. An atom is matter. An electron is matter. A tree is matter. Light is not. Magnetic fields are not. Gravity is not. Energy is not.

Answer 6

Matter is anything that has weight and takes up space.

Answer 7

An illusion made up of very tiny force fields.