Hmmm, well I guess the simplest way I can define them is that bosons are particles that carry/exchange forces (this is not entirely accurate***, there are plenty of bosons that are not force carriers but I think this is the most relevant description in the context we're talking about).
Now the statement that particles carry forces might be confusing straight away because typically when you think of a force in physics you think of a field, e.g. a magnetic field. This fields vs particles question is one that caused much debate, in particular when considering the behaviour of light in the 19th and 20th centuries, and in a sense is not completely resolved today. I won't go in to much detail but you find that light, for example, acts like particles in some cases (see the
Photoelectric Effect) and like a wave/field in others (see
Young's Double Slit Experiment). It turns out that you simply have to accept that light, and in fact all particles, can not simply be defined as a particle or a field - they are both (?!).
This is the beginning of quantum mechanics, which I won't go in to in any detail, but you are not too far from the truth if you think of a boson, a force carrying particle, as the smallest possible 'lump' of field (force) that can be transferred between two objects.
In the Standard Model, the best explanation of the fundamental building blocks of nature that we have, there are three fundamental forces with one or more associated bosons:
Electromagnetic Force (e.g. light, magnetism, electricity etc.) - Photons
Weak Force (e.g. radioactive decay) - W and Z bosons
Strong Force (e.g. binds nuclei together) - gluons
There are two key things missing from this model - a mechanism for generating mass and a boson for gravity. The best theory we have for generating mass is via the Higgs field and the Higgs boson which is considered part of the Standard Model but hasn't been discovered yet. Gravity turns out to be a much harder nut to crack - there is currently no accepted/correct quantum (particle) theory of gravity.
*** The more accurate description is that bosons are particles with integer (whole number) spin, spin being an internal property of particles that is very important in quantum physics. It turns out that you can have more than one boson occupying the same physical state, whereas only a maximum of one 'fermion' (with half-integer spin) can occupy the same state. Protons and atoms are in fact bosons as well.
I'll post about the Higgs seminar some time later, although it was pretty much what I was expecting.
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allow what exists to co-exist with what may or may not exist.
