Last week's announcement of the discovery of a new particle seemed to answer one of the great outstanding questions in physics. But for those who haven't been immersed in all things LHC, the results were likely to raise all sorts of new questions (along with "what was all the fuss about again?"). So, to help navigate the post-Higgs world, we put together a short Q&A, based on questions that some of the Ars staff had.

I know we detected it in the Large Hadron Collider, but how did they actually make Higgs bosons?

There are two ways to answer that question. The first is that we're simply converting energy into matter. The protons in the collider carry a tremendous amount of energy, and it has to go somewhere. Given Einstein's E = mc2, we know that some of that energy can be converted into matter. That's why things that are much heavier than two protons at rest can pop out of the collisions.

But Einstein's equations aren't magic, in that particles don't just poof into existence—there are actual processes that create them. In the LHC, the most common process that ends in a Higgs boson is gluon fusion. Gluons are the (apparently massless) carriers of the strong force that holds quarks together to form things like protons and neutrons. If two of them merge, then one possible outcome is a single Higgs particle.

Everyone says that this particle was predicted by the Standard Model, but how exactly? What was missing that made people theorize the Higgs?

The Standard Model describes the properties of fundamental particles and the forces that mediate their interactions. Some of these, like the photon, are massless; others, like the W and Z bosons that mediate the weak force, weigh as much as entire atoms (including some that the weak force causes to decay). Although its possible to just say "this is what these things weigh," physicists find this sort of approach dissatisfying. So, they developed a theoretical mechanism that could supply some particles with mass.

Several papers, appearing about the same time, suggested that there's a pervasive field that all particles can interact with. Some, like the photon, don't, and remain massless. Others, like the W and Z bosons, undergo large interactions with the field, picking up a large mass in the process. Peter Higgs published the first paper that indicated that this field should have a corresponding particle, which eventually led to it picking up his name: the Higgs boson. (Physicist Matt Strassler has written much more about the particle's history and role in the Standard Model.)

With the discovery of the W, Z, and top quark, the Higgs remained the last particle predicted by the Standard Model that remained undiscovered. Finding it became a key test as to whether the Model provided a complete picture of the basic particles and forces.

Many scientists are being careful about saying that we've only found a boson that looks like the Higgs. What's that supposed to mean?

If you've read our coverage of the Higgs, you know that the Standard Model predicts that it will decay along a variety of specific pathways: two photons, four leptons, etc. The fact that we're seeing something that's a boson, and clearly decays through at least some of these pathways, tells us that we've seen something very much like the Standard Model Higgs.

But it may not be precisely the Standard Model version. So far, we don't have enough collisions to tell the Standard Model apart from some related theories. For example, one rare decay pathway should produce two tau particles. (Taus are part of the lepton family, which includes the electron and its heavier cousin the muon. Think of the tau as the electron's morbidly obese uncle.) So far, the CMS detector has seen none of these decays (the ATLAS team hasn't performed this analysis yet), but their absence isn't yet statistically significant. If that continues as more Higgs are produced, then it will suggest that we're looking at a non-standard Higgs.

What could that be? There are a number of variations on the theory that predict it may take some of those pathways more or less often than the vanilla version of the theory. And there's a major extension to the Standard Model, called supersymmetry, that suggests that the Standard Model's particles are all parts of larger families, meaning that there would be multiple Higgs bosons, and we've only found one. Matt Strassler told Ars that a few more exotic theories suggest there will be Higgs-like particles that do very different things, some involving extra dimensions. It's only by making more of these bosons that we can start to tell these possibilities apart. Which brings us to our next question.

The key thing here is that, if we haven't found the Standard Model Higgs, then we don't get to keep the Standard Model as it is. We could end up with a mildly tweaked version, we could have a Standard Model plus extensions, or we could be seeing hints of something much more significant. Until we have a better understanding of the particle we're seeing, we can't tell any of these apart.

If the Large Hadron Collider was made to find the Higgs, what's it going to do now?

Make more Higgs, so we can answer the previous question, for starters. CERN's director announced that it will run for a few extra months specifically to get a better statistical handle on whether this is the Standard Model Higgs.

Beyond that, many other theoretical particles, including some of those predicted by things like supersymmetry, are already within reach of the energies at the LHC. Once it restarts in a couple of years, it will be running at much higher energies, opening up a greater range for discovery. Even if you don't think it's worth chasing down theoretical particles, the Universe keeps telling us that dark matter is likely to be comprised of a heavy fundamental particle. The LHC should be able to spot these if they're really out there.

Does this eliminate the need to build another collider?

Actually, it will certainly inform, and possibly motivate, the construction of anything that comes next. The LHC may have been a great Higgs discovery machine, but it's actually not so hot if we want to look at the Higgs in detail (and wanting the answers to the above should suggest we do). The problem is that proton collisions are messy, since you're actually colliding what's essentially a bag of quarks, gluons, and virtual particles, all of which may end up carrying some fraction of the total energy. All sorts of things spill out of the resulting collisions, making it difficult to separate out the Higgs decay. Some of the decay channels are so noisy that they actually made the discovery statistics worse in the recent announcements.

A much cleaner way of going about looking at the Higgs would be to collide fundamental particles, ideally with their antiparticles. We could then tune the energy to make producing our 126GeV Higgs much more likely. That was what motivated the construction of SLAC, which smashed electrons together to produce lots of the W and Z bosons.

Unfortunately, building one will be a real challenge. Electrons don't like to go around in circles (they lose energy quickly), so we'd have to build a linear collider, one that is longer than anything we've built previously. That gets expensive. The alternative is to build a muon collider, but this would involve the development of lots of new and unproven technology. In the age of tight science budgets, the prospects for a major construction project look bleak.

That reminds me—the LHC cost a lot of money. Couldn't that have been put to better use?

It's really difficult to guess what scientific advances are going to pay dividends. Logic gates were first considered around 1900; quantum mechanics was developed in the 1930s. It took until the 1970s for them to be married in the form that all of us now use. Restriction enzymes were discovered in the 1960s when people were trying to figure out why only some viruses could infect some bacteria. They ended up being an essential foundation for the biotech industry. I could go on with examples for ages.

If anyone tells you which areas of basic research will have the largest economic impact 30 years from now, I'd bet money they're wrong.

Might the money have done more good in applied research? Possibly, but even there, there are no guarantees. The technology we actually get is often radically different from what we'd want or expect based on the state of scientific knowledge. In other words, we may want and expect flying cars, but we end up with always-online smartphones. And I'd trade them both for fusion power, the basic physics of which we nailed down decades ago.