I sat down with Astronomy magazine Senior Editor Rich Talcott to learn more about the Large Hadron Collider (LHC) and its September 10 test. 
For additional background information on the LHC, visit Astronomy.com.
UPDATE: LHC successfully passed its September 10 test.
Here is the transcript of my conversation with Rich:
What is the Large Hadron Collider?
Well the LHC, as the name implies, is something that’s big, that’s going to collide elementary particles called hadrons. And basically what these guys are are subatomic particles that consist of quarks and are held together by the strong nuclear force. The LHC is going to collide hadrons at tremendous energies.
The most well known hadrons are neutrons and protons. And what the LHC is going to do mainly is collide protons together at stupendous speeds.
The particles are going to be traveling around the 17-mile [16.57 miles] circumference at within one millionth of one percent of the speed of light. We’re talking 99.999999 percent the speed of light.
At those speeds, there’s going to be a tremendous amount of energy released whenever the protons collide. The ring actually has six different experiments that are going to be looking for different results when these particles collide.
The protons make 11,000 trips around the 17-mile loop every second. So it’s 11,000 revolutions per second.
And when it’s fully functioning, they’ll be colliding 600,000,000 protons together at a time. So we’re talking a large number of high-speed protons coming together.
To make this device work, it needs to be cooled to a very low temperature. So it’s 1.9 Kelvin above absolute zero, which means 1.9 degrees Celsius above absolute zero. So it’s extremely cold magnets that are going to keep the particles moving around the circle so that they can be collided together.
Also as you might expect the particles moving around inside this thing would naturally run into air molecules and create collisions as well. So one of the things that they’re going to do is create a vacuum that’s equal to interplanetary space, or actually about 10 percent the density of the Moon’s atmosphere. It’s going to be an extremely good vacuum inside here so that the protons don’t interact with all sorts of other things before they run into each other heading in opposite directions.
What do scientists hope to learn from the LHC experiments?
There are two different ways that scientists are looking at the LHC and what it can do for them. Both physicists and cosmologists are really interested in what’s going on here. And it’s high-energy physicists that get the big play here. One of the particles that scientists believe exists, but has never been detected before, is called the Higgs boson, and it’s also been called the “God particle” because it has such special properties.
Among them being the fact that a lot of scientists think this is the particle that confers mass on every other particle in the universe. So scientists are deeply concerned about finding this particle to learn its properties to see if there may be different versions of this particle out there. We haven’t had an experiment yet that’s been able to reach the energies necessary to create these particles, and so that’s one of the hopes here.
Some people may wonder how colliding particles like protons together actually could create anything because most of the time collisions tend to destroy. But if you remember back to Einstein’s famous equation, E=mc^2, matter and energy are just two different versions of the same property essentially. And so when you’re colliding these particles together the tremendous energy can create matter, and that’s what the scientists are hoping for.
So LHC could reveal God? [laughter]
Well, one of his particles anyway.
The other reason that the Higgs boson is so important to physicists trying to study how the universe is put together is that it’s an essential ingredient in the standard model that physicists have developed to describe how matter works.
These kind of go together into what are often called the grand unified theories that combine the electromagnetic force along with both the strong and weak nuclear forces. And these three of the four forces in the universe are combined in the standard model, and the Higgs boson is essential to making that standard model work.
If the LHC does not turn up the Higgs boson, then that means physicists have to go back to, if not to square one, at least to a low number square in order to be able to figure out how the universe works.
The other aspect that the LHC is going to look at, or what makes cosmologists perhaps most interested is that the conditions that are going to be created within the LHC are the same conditions that existed very early in the universe back when it was less than a second or so old.
And this is going to be the first controlled experiment that we’ve ever had that is going to be able to look back and see what conditions in the early universe are like. So among the things cosmologists are interested in learning is how come there’s a lot more matter than antimatter in the universe. Theory says there should be equal amounts of both. But because whenever matter interacts with antimatter it turns into energy, there shouldn’t be any matter here in the universe; it should’ve all been exploded into energy. Obviously we do have a lot more matter than antimatter, and so there’s some fundamental difference between matter and antimatter, and one of the things that the LHC may be able to get at is what that difference is.
Another thing that they’re going to be looking for is information about dark matter and dark energy, which together make up about 96 percent or so of the mass and energy in the universe. The LHC is going to be looking for something called supersymmetric particles, which may well have a role to play in dark matter and what that is, and so this is going to try to give astronomers and cosmologists an idea of what a good fraction of the universe is made out of.
One other thing that may help cosmologists out is that some of the particles and conditions created may be enough to see whether space has more than the three dimensions that we’re familiar with.
This is one of the things that string theory, a favorite of science-fiction writers and scientists who like to really think out there. String theory may be a way of combining gravity with the three forces that the grand unified theories attempt to unite. One of the predictions of string theory is that there should be many more dimensions than just the three or four of space-time that we tend to think of here in our universe. If it can get at looking at some of these potential extra dimensions, that may give the first experimental evidence of string theory.
What’s happening September 10?
The next big step in the commissioning of the LHC comes on September 10. They’re going to circulate a beam throughout the 17-mile-long tunnel.
The actual first high-energy collisions aren’t going to happen until it’s officially commissioned, and that’s on October 21. Or at least, that’s the current date. So we still have more than a month left before they start colliding these protons at super-high energies to see what comes out.
So September 10 is a test of their being able to circulate the beams and getting them up to the speeds that they want to.
Which is probably, just throwing out a number, 9/10 of what they want to do to make sure everything’s working. If they can circulate a beam, they can presumably circulate them in both directions and collide them. So it’s kind of a minor step beyond being able to circulate the beam at high speeds.
How do they produce the particles?
There’s a linear accelerator that injects the particles into the circular ring, and so it starts the particles at very high energies. The magnets then speed up the protons and keep them moving around the circular path.
They start with high-speed protons that get sped up inside the ring.
Have these experiments ever been done before?
This is easily the highest energy experiment that’s been done, and there have been other experiments that have gone on that have reached lower energies and that have found out much of what’s going on in the universe. So we have a lot of good evidence that the standard model is true based on what earlier experiments have shown. But we haven’t been able to get to the energies needed to see the Higgs boson and to see some of these other effects, so we’re trying to get up to the energy needed to be able to see the next stage of the evolution of the models and the experiments.
So it could confirm what we’ve learned, or it could provide evidence that forces physicists to go back to square one?
It’s always interesting. If scientists knew what an experiment would show, there wouldn’t be any need to run the experiment. This experiment is like all others — basically, we don’t know for sure what it’s going to show, so one of the things is if it finds the Higgs boson and it has the properties physicists expect, then that goes a long ways toward confirming the standard model of particles.
But if the Higgs boson doesn’t exist at what scientists expect, then they’re going to have to go back and try to figure out where the Higgs boson may fit in, if it has different properties, or if they don’t find the Higgs boson, how matter is actually put together and what causes mass in the universe because that’s what the Higgs boson is supposed to be able to do.
Where did the funding come for LHC?
There are actually more than 8,000 scientists and more than 80 countries involved in the LHC and something like 400 universities, so the money came from all of these participants in the project.
Is it the largest collaborative science experiment in the history of science?
Yeah, I think that would be fair to say.
Along the outside of the ring, there are six different experiments set up so it’s not a single experiment; there are going to be six different experiments looking for different things from the proton collisions. And so, you wouldn’t say all 8,000 people are working on the entire thing. There are lots of sub-disciplines that people are working on or experiments that may not have anything to do with the other experiments.
One of the fun things is looking at the author lists on high-energy particle physics papers and these are going to be ... there have been some high-energy particle physics papers that have more than 100 authors on them, and these won’t be any smaller.
Where does LHC rank in terms of scientific instruments throughout history? Bigger than Hubble?
The amount of data that we’re going to get from the LHC, to put it in perspective, it’s enough that if you put it all on CDs, every year there will be enough CDs to go to the Moon and back twice.
So there’s a huge amount of data that is going to come out of this, and it’s teasing out the small effects from that data that’s going to give us all the knowledge that we hope. It’s fair to say that in terms of the basic scientific knowledge that we can and should get out of the LHC, it’s going to be certainly at least as much as Hubble does, but it’s not going to be in the same sense of pretty pictures of what the universe looks like. The universe of the very small is far different from the universe of the very large, and you may have to be a scientist to appreciate the beauty of the very small.
It’s the first controlled experiment that’s going to be able to look back at what conditions were like very shortly after the Big Bang. So we are going to get a look at the universe’s origins in a way that we haven’t had the chance to do before.
What are the potential dangers of flipping the switch September 10?
You may still run across on the Internet examples of people talking about how Mars at this opposition is going to look as big as the Full Moon. Most of the purported problems that are associated with the LHC kind of fall into that same realm of people taking a little bit of knowledge and using it to advance far beyond what might possibly happen.
One of the things that people have talked about is the production of the mini black holes by the particle collisions, and that’s not totally out of the realm of possibility. The thing about black holes it that they tend to evaporate over time, and the smallest black holes evaporate the most quickly. Any black hole created by these particle interactions would disappear within a small fraction of a second, something along the order of a billionth of a billionth of a billionth of a second. So any of these black holes would evaporate before they would have a chance to start devouring anything around them.
People have talked about [LHC creating] conditions that have never been created before in the universe, or not since the Big Bang, which is not necessarily true. We have things called ultra high-energy cosmic rays that rain down on Earth’s atmosphere and these things, believe it or not, have energies far greater than the energies that we’re going to have in these collisions.
Something on the order of a million times stronger; we’ve seen cosmic rays with those energies. Those cosmic rays run into molecules in Earth’s atmosphere and so far haven’t created any black holes that have swallowed Earth or created any strange particles that have developed into anything that could threaten Earth. The fact that the universe is creating experiments similar to what the LHC is going to do, just not in a controlled way, is the best proof that we don’t have anything to worry about here.
Back when they exploded the first atomic bombs in the 1940s, there were a few scientists that predicted that it could launch a chain reaction that would essentially ignite the atmosphere of Earth and burn out all the oxygen in Earth’s atmosphere. That probably had a bigger chance of coming true than this does.
Michio Kaku, a theoretical physicist and someone who has written for Astronomy before, said “These things may be possible, but, technically, so is the fact that the LHC could create a fire-breathing dragon, and they’re about equally probable.”