Mass is the form energy takes on when it is travelling slower than the speed of light.

m=E/c^2

A composition by Igor Stravinsky?

Inertial mass is the reluctance of an object to change its state of motion. Unmoving objects tend to stay at rest and moving objects tend to continue in motion. Why this should be I don’t think anyone knows.

I thought this was a Catholic question.

”[I]nertial mass is just a quantitative measure of an object’s reluctance to accelerate” is a very good way of putting it and will serve any practical purpose.

You may recall CERN announcing not too long ago that they have found evidence for the existence of a long-sought particle called the Higgs boson. The Higgs boson is the particulate embodiment of the Higgs field, and it is thought that the interaction of other forms of matter with this field is what makes them resist acceleration and hence have inertial mass.

Gravitational mass is the result of matter warping spacetime around it. The oft-used analogy is to think of the distortion created on the surface of a mattress or a rubber sheet when you rest a heavy object on it. Einstein’s theory of relativity covers gravitational mass but it is not a theory that is compatible with the quantum theories that govern the other aspects of nature.

That one always uses the same quantity for gravitational mass and inertial mass for a given object makes me wonder if the Higgs field and gravity are linked in some non-trivial way, but I have never heard of any serious ideas from a physicist along those lines.

@Judi Me too.

@Judi @JLeslie You zany papists !

The best answer science has to offer is along the lines of @hiphiphopflipflapflop answer about the Higg’s Boson. The best theories suggest mass is embodied in that particle, and folks using the CERN supercollider are looking for definite evidence of it.

It’s an excellent question, because given the mass of atomic constituents such as electrons, protons and neutrons, they don’t add up to enough to account for the weight of the things that surround us (and make up our bodies). So where does mass come from?

And I don’t think that “Higgs” is a possessive noun. I see the term as “Higgs boson”.

Ooooo @CWOTUS you are correct, it’s not Higg’s, it’s Higgs Boson, named after Peter Higgs who proposed the existence of them in 1964. It could be Higgs’s Boson but that’s…. silly.

@CWOTUS @dabbler me too. I never really thought of it as ‘Higgs’ boson’ but rather as ‘Higgs boson’.

@CWOTUS Wait what, I don’t really get this part: .. they don’t add up to enough to account for the weight of the things that surround us (and make up our bodies). So where does mass come from?

Here you mentioned two completely different things: Weight and mass..

The mass comes from something completely different, and so does Weight. Weight comes as a result of an object’s mass combined with gravitational force. (Therefore the amount of force acting on a body due to grav. force.) W=mg depending on the gravitational pull.(eg. on moon vs on earth)

So gravitational force has a role in terms of accounting for the overall weight, it is not the mass alone that accounts for our weight. And I don’t think the mass is solely dictated by an object’s atomic constituents, but also from its kinematic and energetic content. (However mass is classified into many categories for that specific reason, apparently. eg. inertial, relativistic, gravitational, newtonian, galilean, keplerian etc.) Notice that many atomic constituents have negligible mass, and it goes way deeper than just protons and electrons. In fact, back in 1964, (this is relatively recent in terms of a scientific discovery), the first quark model was proposed by scientists Murray Gell-Mann and George Zweig, and the last ‘flavor’, the ‘top quark’ was the last to be discovered in 1995. This clearly shows that discoveries are endless, so there many more things to discover. Quarks are defined as ‘elementary particles and fundamental constituents of matter.’ Is that an absolute case, though?

Personally I believe mass cannot remain exactly 100% constant. It opposes everything mass is about, but it’s always something I’ve believed, I guess. Be it such small changes in the atomic components of our environment, be it minor changes in our atomic components.

The field of physics still contains many gaps to be filled, and I think it is with a combination of people’s varied knowledge and corresponding experiments based on that, that we can come to a conclusion.

E= mc^2 explained in less than 2 minutes
http://www.youtube.com/watch?v=NnMIhxWRGNw&feature=plcp