*Jim Kelley asked the Naked Scientists:*

I've heard that they Higgs Boson is what gives mass to objects. I've also heard that when objects approach the speed of light they gain mass and when they go the speed of light they have infinite mass.

How does this work with regards to the Higgs boson? Do objects approaching the speed of light draw Higgs bosons to them from around them to gain that mass? Or have I totally misunderstood this process?

As I understand it, it's not the Higgs boson itself that gives mass, but the Higgs field (the Higgs boson is a quantised excitation of the Higgs field). Certain fundamental particles interact (couple) with the Higgs field and this gives them mass. The stronger the coupling, the greater the mass. A particle approaching the speed of light has kinetic energy (energy of motion) that also gives it equivalent mass (mass-energy equivalence). No particle can accelerate to reach the speed of light, as the mass due to their kinetic energy would become infinite. Only massless particles (that don't couple with the Higgs field) can travel at the speed of light, and they can

*only* travel at the speed of light.