The Large Hadron Collider (LHC) will become the world’s largest and highest-energy producing particle accelerator when it becomes operational between August and October 2008.
According to CERN, “The LHC reproduces in the laboratory, under controlled conditions, collisions at centre-of-mass energies less than those reached in the atmosphere by some of the cosmic rays that have been bombarding the Earth for billions of years.”
The LHC will accelerate protons to energies of up to 7 trillion electron volts. The protons will then be crashed into one another at nearly the speed of light.
Such collisions will create energies and densities that are similar to those occurring less than a second after the Big Bang, the theoretical beginning of our Universe—our existence.
The European Organization for Nuclear Research (CERN) built the LHC between the borders of France and Switzerland, near Geneva, Switzerland.
When fully operational the LHC may be able to produce the Higgs boson, an elusive little particle that will help cosmologists piece together some unknown facets within the Standard Model of particle physics.
The LHC may possibly even help physicists develop a theory (called the Grand Unified Theory, or GUT for short) that unifies three of the four known fundamental forces of nature: electromagnetism, the strong nuclear force, and the weak nuclear force.
The theory will not, however, unity these three forces with the remaining force: gravity. (If someone should be able to unity all four forces, then they would have developed a very important theory that scientists call the Theory Of Everything (TOE).
The problem externally to the LHC has been perceived safety concerns with some people about whether black holes possibly produced by the LHC could destroy the Earth. Please read on.
The problem with getting the LHC up and running has been with a group of people who think that the large particle accelerator will produce such things as black holes and other exotic phenomena, which could possibly destroy the Earth.
In fact, seven of these people filed an injunction against CERN, specifically challenging the operational safety of the LHC, in the U.S. District Court of Hawaii in March 2008.
In response, two safety reviews were performed on the theory behind the LHC and its actual operations. A group of independent scientists, called the LHC Safety Study Group, performed an analysis in 2003 and found that the LHC “presented no danger.”
In 2008, members of the LHC Safety Assessment Group (LSAF) published a report undating the 2003 report. The independent particle physicists re-affirmed the conclusions of the LHC Safety StudyGroup.
The CERN Scientific Policy Committee, a group of scientists, external to CERN that advises the organization, endorsed the conclusions of the LSAF.
A safety review (“Review of the Safety of LHC Collisions”) was released on June 20, 2008, by CERN concerning the safety aspects of the LHC.
A summary of the LSAF report is found at CERN's website "The Safety of the LHC."
The conclusion of the report is quoted on the third page.
Their conclusion is (with bolded text added for emphasis):
“We recall the rates for the collisions of cosmic rays with the Earth, Sun, neutron stars, white dwarfs and other astronomical bodies at energies higher than the LHC. The stability of astronomical bodies indicates that such collisions cannot be dangerous.”
“Specifically, we study the possible production at the LHC of hypothetical objects such as vacuum bubbles, magnetic monopoles, microscopic black holes and strangelets, and find no associated risks.”
“Any microscopic black holes produced at the LHC are expected to decay by Hawking radiation before they reach the detector walls. If some microscopic black holes were stable, those produced by cosmic rays would be stopped inside the Earth or other astronomical bodies. The stability of astronomical bodies constrains strongly the possible rate of accretion by any such microscopic black holes, so that they present no conceivable danger.”
“In the case of strangelets, the good agreement of measurements of particle production at RHIC with simple thermodynamic models constrains severely the production of strangelets in heavy-ion collisions at the LHC, which also present no danger.”
(Strangelets, sometimes also called "strange nuggets," are theorized objects that consist of a bound state (several particles acting as one object) with generally equal numbers of up, down, and strange quarks.)
As reported by Science News, “Any black holes created at a new particle accelerator near Geneva will not make Swiss cheese of the nearby countryside. Nor will they gobble up Earth.” [Science News (subscription required): “Safe from black holes”]
Further information about the background of the LHC and the safety concerns people have had can be found at:
Ars Technica (by John Timmer): “Safety report: latest collider at CERN won't end the world”
About.com/Physics (by Andre Zimmerman Jones): “New CERN Safety Report - Still No Doomsday Scenario”
Timmer concludes (with bold text for emphasis), "Overall, it's hard to read this report and not wind up viewing the apocalyptic fears as simply being poorly thought through. It was striking how clearly the worries over the LHC have parallels to the fears over biotechnology, which came up during our recent interview with Carl Zimmer. There too, billions of years of natural experiments and decades' worth of scientific experiment should be informing our view of safety; for at least some segment of the public, that's not happening."