To me, the Higgs particle and the associated Higgs mechanism had always seemed like an unfortunate hack. In setting up the Standard Model, one begins with a mathematically quite pristine theory in which every particle is perfectly massless. But in reality almost all particles (apart from the photon) have nonzero masses. And the point of the Higgs mechanism is to explain this—without destroying desirable features of the original mathematical theory.
Here’s how it basically works. Every type of particle in the Standard Model is associated with waves propagating in a field—just as photons are associated with waves propagating in the electromagnetic field. But for almost all types of particles, the average amplitude value of the underlying field is zero. But for the Higgs field, one imagines something different. One imagines instead that there’s a nonlinear instability that’s built into the mathematical equations that govern it, that leads to a nonzero average value for the field throughout the universe.
And it’s then assumed that all types of particles continually interact with this background field—in such a way as to act so that they have a mass. But what mass? Well, that’s determined by how strongly a particle interacts with the background field. And that in turn is determined by a parameter that one inserts into the model. So to get the observed masses of the particles, one’s just inserting one parameter for each particle, and then arranging it to give the mass of the particle.
That might seem contrived. But at some level it’s OK. It would have been nice if the theory had predicted the masses of the particles. But given that it does not, inserting their values as interaction strengths seems as reasonable as anything.
Still, there’s another problem. To get the observed particle masses, the background Higgs field that exists throughout the universe has to have an incredibly high density of energy and mass. Which one might expect would have a huge gravitational effect—in fact, enough of an effect to cause the universe to roll up into a tiny ball. Well, to avoid this, one has to assume that there’s a parameter (a “cosmological constant”) built right into the fundamental equations of gravity that cancels to incredibly high precision the effects of the energy and mass density associated with the background Higgs field.
And if this doesn’t seem implausible enough, back around 1980 I was involved in noticing something else: this delicate cancellation can’t survive at the high temperatures of the very early Big Bang universe. And the result is that there has to be a glitch in the expansion of the universe. My calculations said this glitch would not be terribly big—but stretching the theory somewhat led to the possibility of a huge glitch, and in fact an early version of the whole inflationary universe scenario.