Safety of particle collisions at the Large Hadron Collider

Concerns have been raised in the media, on the Internet and through the law courts about the safety of the particle physics experiments planned to take place at the Large Hadron Collider (LHC), the world's largest and most powerful particle accelerator to date, built by the European Organization for Nuclear Research (CERN) near Geneva, in Switzerland.Boyle, Alan (2 September 2008). " [http://cosmiclog.msnbc.msn.com/archive/2008/09/02/1326534.aspx Courts weigh doomsday claims] ". "Cosmic Log". msnbc.com.] Hawley, Charles (6 August 2008). " [http://www.spiegel.de/international/world/0,1518,570487,00.html Physicists Allay Fears of the End of the World] ". "Spiegel Online".] The claimed dangers of the LHC particle collisions, which are expected to begin in the spring of 2009," [http://press.web.cern.ch/press/PressReleases/Releases2008/PR10.08E.html LHC re-start scheduled for 2009] " (PR10.08). CERN Press Office. 23 September 2008.] include doomsday scenarios involving the production of stable micro black holes and the creation of hypothetical particles called strangelets.

To address such concerns, CERN mandated a group of independent scientists to review these scenarios. In a report issued in 2003, they concluded that, like current particle experiments such as the Relativistic Heavy Ion Collider (RHIC), the LHC particle collisions pose no conceivable threat.Blaizot JP, Iliopoulos J, Madsen J, Ross GG, Sonderegger P, Specht HJ (2003). " [http://doc.cern.ch/yellowrep/2003/2003-001/p1.pdf Study of Potentially Dangerous Events During Heavy-Ion Collisions at the LHC] " (PDF, 176 KiB). CERN. Geneva. [http://cdsweb.cern.ch/search?sysno=002372601cer CERN-2003-001] .] A second review of the evidence commissioned by CERN was released in 2008. The report, prepared by a group of physicists not involved in the LHC experiments, reaffirmed the safety of the LHC collisions in light of further research conducted since the 2003 assessment.Ellis J, Giudice G, Mangano ML, Tkachev I, Wiedemann U (LHC Safety Assessment Group) (5 September 2008). " [http://arxiv.org/pdf/0806.3414 Review of the Safety of LHC Collisions] " (PDF, 586 KiB). . 35, 115004 (18pp). . . [http://cdsweb.cern.ch/record/1111112?ln=fr CERN record] .] " [http://public.web.cern.ch/public/en/LHC/Safety-en.html The safety of the LHC] ". CERN 2008 (CERN website).] It was reviewed and endorsed by a CERN committee of 20 external scientists and by the Executive Committee of the Division of Particles & Fields of the American Physical Society, and was later published in the peer-reviewed "."CERN Scientific Policy Committee (2008). " [http://indico.cern.ch/getFile.py/access?contribId=20&resId=0&materialId=0&confId=35065 SPC Report on LSAG Documents] ". [http://cdsweb.cern.ch/record/1113558?ln=fr CERN record] .] " [http://www.aps.org/units/dpf/governance/reports/upload/lhc_saftey_statement.pdf Statement by the Executive Committee of the DPF on the Safety of Collisions at the Large Hadron Collider] " (PDF, 40 KiB) issued by the [http://www.aps.org/units/dpf/ Division of Particles & Fields] (DPF) of the American Physical Society (APS)] The report concludes that any doomsday scenarios at the LHC are ruled out because the physical conditions and events that will be created in the LHC experiments occur naturally in the universe without hazardous consequences.

Particle accelerator

The Large Hadron Collider (LHC) is the world's largest and highest-energy particle accelerator complex, intended to collide opposing beams of protons (one of several types of hadrons) with very high kinetic energy.CERN Communication Group (January 2008). " [http://cdsmedia.cern.ch/img/CERN-Brochure-2008-001-Eng.pdf CERN FAQ — LHC: the guide] " (PDF). CERN. Geneva (44p).] Achenbach, Joel (1 March 2008). " [http://ngm.nationalgeographic.com/2008/03/god-particle/achenbach-text The God Particle] ". "National Geographic Magazine".] It was built by the European Organization for Nuclear Research (CERN) near Geneva, in Switzerland. The LHC's main purpose is to explore the validity and limitations of the Standard Model, the current theoretical picture for particle physics. The first particle collisions at the LHC are planned to take place in the spring of 2009, with the full energy nowrap|14 TeV (center-of-mass) collisions planned to begin thereafter.

afety concerns

In the run up to the commissioning of the LHC, Walter L. Wagner (an American botanist and former radiation safety officer, as well as an original opponent of the RHIC), Luis Sancho (a Spanish science writer) and Otto Rössler (a German biochemist) have expressed concerns over the safety of the LHC, and have attempted to halt the beginning of the experiments through petitions to the US and European Courts.Boyle, Alan (2 September 2008). " [http://cosmiclog.msnbc.msn.com/archive/2008/09/02/1326534.aspx Courts weigh doomsday claims] ". "Cosmic Log". msnbc.com.] " [http://edition.cnn.com/2008/TECH/06/30/doomsdaycollider.ap/index.html Some fear debut of powerful atom-smasher] " "CNN.com". 30 June 2008.] [Muir, Hazel. (28 March 2008). " [http://www.newscientist.com/article/dn13555 Particle smasher 'not a threat to the Earth'] ". "NewScientist.com".] Overbye, Dennis (21 June 2008). " [http://www.nytimes.com/2008/06/21/science/21cernw.html Earth Will Survive After All, Physicists Say] ". "The New York Times".] [Sancho, Luis (June 2008). " [http://www.harpers.org/archive/2008/06/0082053 Fear review] ". "Harper's Magazine". ] These opponents assert that the LHC experiments have the potential to create low velocity micro black holes that could grow in mass or release dangerous radiation leading to doomsday scenarios, such as the destruction of the Earth.Boyle, Alan (19 August 2008). " [http://cosmiclog.msnbc.msn.com/archive/2008/08/19/1276192.aspx?Ajax_CallBack=true Twists in the Doomsday debate] ". "Cosmic Log". msnbc.com.] Boyle, Alan (27 March 2008). " [http://cosmiclog.msnbc.msn.com/archive/2008/03/27/823924.aspx Doomsday Fears Spark Lawsuit] ". "Cosmic Log". msnbc.com.] Other claimed potential risks include the creation of theoretical particles called strangelets, magnetic monopoles and vacuum bubbles.

Based on such safety concerns, US federal judge Richard Posner, Future of Humanity Institute research associate Toby Ord and others have argued that the LHC experiments are too risky to undertake, [Bailey, Ronald (2 September 2008). " [http://www.reason.com/news/show/128492.html A 1-in-1,000 Chance of Götterdämmerung: Will European physicists destroy the world?] ". "Reason Magazine".] [Crease, Robert P. (May 2005). " [http://physicsworldarchive.iop.org/index.cfm?action=summary&doc=18%2F5%2Fphwv18i5a24%40pwa-xml&qt= Are accelerators dangerous?] " "Physics World".] [Warner, Gerald (10 September 2008). " [http://www.telegraph.co.uk/opinion/main.jhtml?xml=/opinion/2008/09/10/do1005.xml We must be wary of scientific research] ". "telegraph.co.uk".] [Deatrick, Sherry R. (May–June 2008). " [http://www.system-safety.org/ejss/focus_p1.php Large Hadron Collider: Cause for ConCERN or Tempest in a Teapot?] " "Journal of System Safety". Vol. 44, No. 3.] In the book "", English cosmologist and astrophysicist Martin Rees calculated an upper limit of 1 in 50 million for the probability that the Large Hadron Collider will produce a global catastrophe or black hole. However, Rees has also reported not to be "losing sleep over the collider," and trusts the scientists who have built it. [Overbye, Dennis (15 April 2008). " [http://www.nytimes.com/2008/04/15/science/15risk.html Gauging a Collider’s Odds of Creating a Black Hole] ". "The New York Times".] He has stated: "My book has been misquoted in one or two places. I would refer you to the up-to-date safety study."

These risk assessments of catastrophic scenarios at the LHC have sparked fears among the public, and scientists associated with the project have received protests. The Large Hadron Collider team revealed that they had received death threats and threatening emails and phone calls demanding the experiment be halted.Highfield, Roger (5 September 2008). " [http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2008/09/05/scilhc105.xml Scientists get death threats over Large Hadron Collider] ". "Telegraph.co.uk".] nowrap|On 9 septembrie 2008, Romania's Conservative Party held a protest before the European Commission mission to Bucharest, demanding that the experiment be halted because it feared that the LHC could create dangerous black holes. [" [http://english.hotnews.ro/stiri-top_news-4283851-update-small-romanian-party-sparks-mockery-saying-lhc-experiment-may-create-tiny-black-holes-and-that-cern-experiment-should-halted.htm UPDATE: Small Romanian party sparks mockery saying LHC experiment may create tiny black holes and that CERN experiment should be halted] ". "Hotnews.ro". 9 septembrie 2008.] [" [http://www.photonics.com/content/news/2008/September/9/93181.aspx Threats Won't Stop Collider] ". "Photonics.Com". 9 September 2008.]

Media coverage of safety concerns

The safety concerns regarding the LHC collisions have attracted widespread media attention. Various widely circulated newspapers have reported doomsday fears in connection with the collider, including The Times,Sugden, Joanna (6 September 2008). " [http://www.timesonline.co.uk/tol/news/uk/article4682260.ece Large Hadron Collider will not turn world to goo, promise scientists] ". "Times Online."] The Guardian,Carus, Felicity (7 September 2008). " [http://www.guardian.co.uk/news/blog/2008/sep/07/1 Should we be concerned when the world's largest subatomic particle experiment is switched on in Geneva?] " "guardian.co.uk".] The Independent,Connor, Steve (5 September 2008). " [http://www.independent.co.uk/news/science/the-big-question-is-our-understanding-of-the-universe-about-to-be-transformed-919480.html The Big Question: Is our understanding of the Universe about to be transformed?] ". "The Independent".] The Sydney Morning Herald," [http://news.smh.com.au/world/massive-physics-experiment-on-wednesday-20080908-4byr.html Massive physics experiment on Wednesday] ". "The Sydney Morning Herald". 8 September 2008.] and Time.Harrell, Eben (4 September 2008). " [http://www.time.com/time/health/article/0,8599,1838947,00.html?imw=Y Collider Triggers End-of-World Fears] ". "Time.com".] Among other media sources, CNN mentioned that "Some have expressed fears that the project could lead to the Earth's demise,"Landau, Elizabeth (8 September 2008). " [http://edition.cnn.com/2008/TECH/09/08/lhc.collider/?iref=mpstoryview Multibillion-dollar collider to probe nature's mysteries] ". CNN.] but it assured its readers with comments from scientists like John Huth, who said that it was "baloney". MSNBC said that, "there are more serious things to worry about"Boyle, Alan (12 September 2008). " [http://cosmiclog.msnbc.msn.com/archive/2008/09/12/1386080.aspx Big Bang sparks big reaction] ". "Cosmic Log". msnbc.] and allayed fears that "the atom-smasher might set off earthquakes or other dangerous rumblings". The results of an online survey it conducted "indicate that a lot of [the public] know enough not to panic". The BBC stated, "the scientific consensus appears to be on the side of CERN's theorists"Rincon, Paul (23 June 2008). " [http://news.bbc.co.uk/1/hi/sci/tech/7468966.stm Earth 'not at risk' from collider] ". "BBC News".] who say the LHC has "no conceivable danger". Brian Greene in the New York Times reassured readers by saying,"If a black hole is produced under Geneva, might it swallow Switzerland and continue on a ravenous rampage until the earth is devoured? It’s a reasonable question with a definite answer: no."Greene, Brian (11 September 2008). " [http://www.nytimes.com/2008/09/12/opinion/12greene.html?_r=1&pagewanted=1&ref=opinion&oref=slogin The Origins of the Universe: A Crash Course] ." "The New York Times".]

The tabloids also covered the safety concerns. The Daily Mail produced headlines such as "End of the world postponed as broken Hadron Collider out of commission until the spring" [" [http://www.dailymail.co.uk/sciencetech/article-1058710/End-world-postponed-broken-Hadron-Collider-commission-spring.html End of the world postponed as broken Hadron Collider out of commission until the spring] ". "Daily Mail". 24 September 2008.] and "Are we all going to die next Wednesday?" [" [http://www.dailymail.co.uk/sciencetech/article-1052354/Are-going-die-Wednesday.html Are we all going to die next Wednesday?] ". "Daily Mail".] The Sun quoted Otto Rössler saying, "The weather will change completely, wiping out life. There will be a Biblical Armageddon."" [http://www.thesun.co.uk/sol/homepage/news/article1660207.ece Boffins set to cause Big Bang] ". "The Sun". 8 September 2008.] After the launch of the collider, it had a story entitled, "Success! The world hasn't ended"." [http://www.thesun.co.uk/sol/homepage/news/article1668971.ece Success! The world hasn't ended] ". "The Sun". 10 September 2008.]

On nowrap|10 September 2008, a 16-year-old girl from Sarangpur, Madhya Pradesh, India committed suicide, having become distressed about predictions of an impending "doomsday" made on an Indian news channel covering the LHC." [http://news.bbc.co.uk/2/hi/south_asia/7609631.stm Girl suicide 'over Big Bang fear'] ". "BBC News". 11 September 2008.]

afety reviews

Concerns similar to those for the LHC were raised in connection with the Relativistic Heavy Ion Collider (RHIC) particle accelerator.Matthews, Robert (28 August 1999). " [http://www.newscientist.com/article/mg16322014.700-a-black-hole-ate-my-planet.html A Black Hole Ate My Planet] ". "New Scientist".] "Horizon: End Day". BBC. 2005.] Wagner, Walter (July 1999). "Black holes at Brookhaven?". (Letters to the Editors) "Scientific American". 281: 8.] Wilczek, Frank (July 1999). "Reply to “Black holes at Brookhaven” by W.L. Wagner". "Scientific American". 281(1): 5.] After detailed studies, scientists reached such conclusions as "beyond reasonable doubt, heavy-ion experiments at RHIC will not endanger our planet"Dar, Arnon; De Rújula, Alvaro; & Heinz, Ulrich (16 December 1999). " [http://arxiv.org/pdf/hep-ph/9910471v1 Will relativistic heavy ion colliders destroy our planet?] " (PDF). "Physics Letters B". 470(1): 142-48. . . [http://cdsweb.cern.ch/record/479729?ln=fr CERN-TH/99-324] .] and that there is "powerful empirical evidence against the possibility of dangerous strangelet production."Jaffe, Robert L.; Busza, Wit; Sandweiss, Jack; & Wilczek, Frank. (14 July 2000). " [http://arxiv.org/pdf/hep-ph/9910333v3 Review of Speculative “Disaster Scenarios” at RHIC] " (PDF). "Reviews of Modern Physics". 72(4): 1125-140. . . [http://cdsweb.cern.ch/record/403566?ln=fr MIT-CTP-2908] .]

CERN-commissioned reports

Drawing from research performed to assess the safety of the RHIC collisions, the LHC Safety Study Group, a group of independent scientists, performed a safety analysis of the LHC, and released their findings in the 2003 report "Study of Potentially Dangerous Events During Heavy-Ion Collisions at the LHC". The report concluded that there is "no basis for any conceivable threat". Several of its arguments were based on the predicted evaporation of hypothetical micro black holes by Hawking radiation and on the theoretical predictions of the Standard Model with regard to the outcome of events to be studied in the LHC. One argument raised against doomsday fears was that collisions at energies equivalent to and higher than those of the LHC have been happening in nature for billions of years apparently without hazardous effects, as ultra-high-energy cosmic rays impact Earth's atmosphere and other bodies in the universe.

In 2007, CERN mandated a group of five particle physicists not involved in the LHC experiments — the LHC Safety Assessment Group (LSAG), consisting of John Ellis, Gian Giudice, Michelangelo Mangano and Urs Wiedemann, of CERN, and Igor Tkachev, of the Institute for Nuclear Research in Moscow — to monitor the latest concerns about the LHC collisions. On nowrap|20 June 2008, in light of new experimental data and theoretical understanding, the LSAG issued a report updating the 2003 safety review, in which they reaffirmed and extended its conclusions that "LHC collisions present no danger and that there are no reasons for concern". The LSAG report was then reviewed by CERN’s Scientific Policy Committee (SPC), a group of external scientists that advises CERN’s governing body, its Council.CERN Scientific Policy Committee (2008). " [http://indico.cern.ch/getFile.py/access?contribId=20&resId=0&materialId=0&confId=35065 SPC Report on LSAG Documents] ". [http://cdsweb.cern.ch/record/1113558?ln=fr CERN record] .] " [http://press.web.cern.ch/press/PressReleases/Releases2008/PR05.08E.html CERN Council looks forward to LHC start-up] ". PR05.08 (20 June 2008). CERN 2008.] The report was reviewed and endorsed by a panel of five independent scientists, Peter Braun-Munzinger, Matteo Cavalli-Sforza, Gerard 't Hooft, Bryan Webber and Fabio Zwirner, and their conclusions were unanimously approved by the full 20 members of the SPC. On nowrap|5 September 2008, the LSAG's "Review of the safety of LHC collisions" was published in the "".

Following the July 2008 release of the LSAG safety report, the Executive Committee of the Division of Particles and Fields (DPF) of the American Physical Society, the world's second largest organization of physicists, issued a statement approving the LSAG's conclusions and noting that "this report explains why there is nothing to fear from particles created at the LHC"." [http://www.aps.org/units/dpf/governance/reports/upload/lhc_saftey_statement.pdf Statement by the Executive Committee of the DPF on the Safety of Collisions at the Large Hadron Collider] " (PDF) issued by the [http://www.aps.org/units/dpf/ Division of Particles & Fields] (DPF) of the American Physical Society (APS)] On nowrap|1 August 2008, a group of German quantum physicists, the Committee for Elementary Particle Physics (KET), [http://www.ketweb.de/ Website of the Committee for Elementary Particle Physics (KET)] (in German).] published an open letter further dismissing concerns about the LHC experiments and carrying assurances that they are safe based on the LSAG safety review.Mättig, Peter (1 August 2008). " [http://www.ketweb.de/pressemitteilungen/20080801_PM_Der_LHC_ist_sicher.pdf Official statement of the German Committee for Elementary Particle Physics (KET)] " (in German) (PDF, 21 KiB). Committee for Elementary Particle Physics (KET).]

Other publications

On nowrap|20 June 2008, Steven Giddings and Michelangelo Mangano issued a research paper titled the "Astrophysical implications of hypothetical stable TeV-scale black holes", where they develop arguments to exclude any risk of dangerous black hole production at the LHC.Giddings, Steven B.; & Mangano, Michelangelo L. (18 August 2008). " [http://physics.aps.org/pdf/10.1103/PhysRevD.78.035009.pdf Astrophysical implications of hypothetical stable TeV-scale black holes] " (PDF, 919 KiB). "Physical Review D". 78, 035009 (47 pages). . . [http://cdsweb.cern.ch/record/1111084?ln=fr CERN-PH-TH/2008-025] .] On nowrap|18 August 2008, this safety review was published in the "Physical Review D", [Mgrdichian, Laura (1 September 2008). " [http://www.physorg.com/news139467844.html Physicists Rule Out the Production of Dangerous Black Holes at the LHC] ". "PhysOrg.com".] and a commentary article which appeared the same day in the journal "Physics" endorsed Giddings' and Mangano's conclusions.Peskin, Michael (18 August 2008). " [http://physics.aps.org/articles/v1/14 The end of the world at the Large Hadron Collider?] ". "Physics". 1 (14). American Physical Society. .] The LSAG report draws heavily on this research.

afety arguments

Micro black holes

Although the Standard Model of particle physics predicts that LHC energies are far too low to create black holes, some extensions of the Standard Model posit the existence of extra spatial dimensions, in which it would be possible to create micro black holes at the LHC at a rate on the order of one per second.Barrau, Aurélien; & Grain, Julien (12 November 2004). " [http://cerncourier.com/cws/article/cern/29199 The case for mini black holes] ". "CERN Courier". CERN.] Schewe, Phillip F.; Stein, Ben; & Riordon, James (26 September 2001). " [http://newton.ex.ac.uk/aip/physnews.558.html Physics News Update] ". "The American Institute of Physics Bulletin of Physics News". Number 558.] [Dimopoulos, Savas; & Landsberg, Greg (27 September 2001). " [http://arxiv.org/pdf/hep-ph/0106295v1 Black Holes at the LHC] " (PDF). "Physical Review Letters" 87: 161602 (4p). . .] According to the standard calculations these are harmless because they would quickly decay by Hawking radiation. Hawking radiation is a thermal radiation predicted to be emitted by black holes due to quantum effects. Because Hawking radiation allows black holes to lose mass, black holes that lose more matter than they gain through other means are expected to dissipate, shrink, and ultimately vanish. Smaller micro black holes (MBHs), which could be produced at the LHC, are currently predicted by theory to be larger net emitters of radiation than larger black holes, and to shrink and dissipate instantly. [Cavaglià, Marco (29 January 2007). " [http://www.einstein-online.info/en/spotlights/accelerators_bh/index.html Particle accelerators as black hole factories?] ". "Einstein-Online." Max Planck Institute for Gravitational Physics (Albert Einstein Institute).] The LHC Safety Assessment Group (LSAG) indicates that "there is broad consensus among physicists on the reality of Hawking radiation, but so far no experiment has had the sensitivity required to find direct evidence for it."

According to the LSAG, even if micro black holes were produced by the LHC and were stable, they would be unable to accrete matter in a manner dangerous for the Earth. They would also have been produced by cosmic rays and have stopped in neutron stars and white dwarfs, and the stability of these astronomical bodies means that they cannot be dangerous: [Schewe, Phil (9 September 2008). " [http://www.aip.org/pnu/2008/split/871-1.html Mini Black Holes No Danger] ". "Inside Science Research — Physics news update". Number 871 #1. American Institute of Physics.]

trangelets

Strangelets are small fragments of strange matter—a hypothetical form of quark matter—that contain roughly equal numbers of up, down, and strange quarks and that are more stable than ordinary nuclei (strangelets would range in size from a few femtometers to a few meters across). If strangelets can actually exist, and if they were produced at the LHC, they could conceivably initiate a runaway fusion process in which all the nuclei in the planet would be converted to strange matter, similar to a strange star.

The probability of the creation of strangelets decreases at higher energies. As the LHC operates at higher energies than the RHIC or the heavy ion programs of the 1980s and 1990s, the LHC is less likely to produce strangelets than its predecessors. Furthermore, models indicate that strangelets are only stable or long-lived at low temperatures. Strangelets are bound at low energies (in the range of 1-10 MeV), whilst the collisions in the LHC release energies in the range of 14 TeV. The second law of thermodynamics precludes the formation of a cold condensate that is an order of magnitude cooler than the surrounding medium. This can be illustrated by the example of trying to form an ice cube in boiling water.

pecific concerns and responses

Otto Rössler, a German chemistry professor at the University of Tübingen, argues that micro black holes created in the LHC could grow exponentially.Rössler, Otto (2008). " [http://www.wissensnavigator.com/documents/spiritualottoeroessler.pdf A Rational and Moral and Spiritual Dilemma] " (PDF, 24 KiB).] Rössler, Otto (2008). " [http://www.wissensnavigator.com/documents/OTTOROESSLERMINIBLACKHOLE.pdf Abraham-Solution to Schwarzschild Metric Implies That CERN Miniblack Holes Pose a Planetary Risk] " (PDF, 88 KiB).] Patorski, Gregor (10 September 2008). " [http://www.20min.ch/news/wissen/story/24668213 Grösstes Verbrechen der Menschheit] " (in German). "20 Minuten".] " [http://www.nzz.ch/nachrichten/wissenschaft/unverstaendnis_fuer_couchepins_dialog_mit_einem_kritiker_des_cern_1.790605.html Publicity für eine fragwürdige Hypothese] " (in German). "NZZ Online". nowrap|23 July 2008.] On 4 July 2008, Rössler met with a CERN physicist, Rolf Landua, at the LHC, with whom he discussed his safety concerns.Schmidt, Von Wolf (7 September 2008). " [http://www.taz.de/1/zukunft/wissen/artikel/1/der-prophet-des-planetentods/ Der Prophet des Planetentods] " (in German). "Taz.de".] Following the meeting, Landua asked another expert, Hermann Nicolai, Director of the Albert Einstein Institute, in Germany, to examine Rössler's arguments. Nicolai reviewed Otto Rössler's research paper on the safety of the LHC and issued a statement highlighting logical inconsistencies and physical misunderstandings in Rössler's arguments."Comments from Prof. Dr. Hermann Nicolai, Director, Max Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut) Potsdam, Germany on speculations raised by Professor Otto Rössler about the production of black holes at the LHC." (July 2008) [http://environmental-impact.web.cern.ch/environmental-impact/Objects/LHCSafety/NicolaiComment-en.pdf] (PDF, 16 KiB).] Nicolai concluded that "this text would not pass the referee process in a serious journal." Domenico Giulini also commented with Hermann Nicolai on Otto Rössler's thesis, concluding that "his argument concerns only the General Theory of Relativity (GRT), and makes no logical connection to LHC physics; the argument is not valid; the argument is not self-consistent."Giulini, Domenico; and Nicolai, Hermann (August 2008). " [http://environmental-impact.web.cern.ch/environmental-impact/Objects/LHCSafety/NicolaiFurtherComment-en.pdf On the arguments of O.E. Rössler] " (PDF, 96 KiB).] On nowrap|1 August 2008, a group of German physicists, the Committee for Elementary Particle Physics (KET), published an open letter further dismissing Rössler's concerns and carrying assurances that the LHC is safe. Otto Rössler was due to meet Swiss president Pascal Couchepin in mid August to discuss this concern," [http://www.nzz.ch/nachrichten/kultur/literatur_und_kunst/roessler_schwarze_loecher_cern_couchepin_1.789024.html Couchepin trifft Cern-Kritiker Rössler] " (in German). "NZZ Online". nowrap|21 July 2008.] but it was later reported that the meeting had been canceled as it was believed Rössler and his fellow opponents would have used the meeting for their own publicity." [http://www.nzz.ch/nachrichten/wissenschaft/kein_gespraech_zwischen_couchepin_und_cern-kritiker_1.810880.html Kein Gespräch zwischen Couchepin und Cern-Kritiker] " (in German). "NZZ Online". nowrap|20 August 2008.]

On nowrap|10 August 2008, Rainer Plaga, a German astrophysicist, posted a research paper on the arXiv Web archive concluding that LHC safety studies have not definitely ruled out the potential catastrophic threat from microscopic black holes, including the possible danger from Hawking radiation emitted by black holes.Plaga, Rainer (10 August 2008). " [http://arxiv.org/pdf/0808.1415v2 On the potential catastrophic risk from metastable quantum-black holes produced at particle colliders] " (PDF, 135 KiB). .] [Clery, Daniel; & Cho, Adrian (5 September 2008). "Large Hadron Collider: Is the LHC a Doomsday Machine?" "Science". Vol. 321. no. 5894, p. 1291. .] [Taylor, Drew (15 September 2008). " [http://www.cw.ua.edu/ua_physicist_s_paper_used_in_lawsuit UA physicist's paper used in lawsuit: Research used as evidence against particle collider] ". "Crimson White".] [Brean, Joseph (9 September 2008). " [http://www.nationalpost.com/news/story.html?id=777940&p=1 Is the end nigh? Science experiment could swallow Earth, critics say] ". "National Post".] In a follow-up paper posted on the arXiv archive on nowrap|29 August 2008, Steven Giddings and Michelangelo Mangano, the authors of the research paper "Astrophysical implications of hypothetical stable TeV-scale black holes", responded to Rainer Plaga's concerns.Giddings, Steven B.; & Mangano, Michelangelo L. (29 August 2008). " [http://arxiv.org/pdf/0808.4087v1 Comments on claimed risk from metastable black holes] " (PDF). . CERN-PH-TH/2008-184.] They point out what they see as a basic inconsistency in Plaga's calculation, and argue that their own conclusions on the safety of the collider, as referred to in the LHC safety assessment (LSAG) report, remain robust. Giddings and Mangano also refer to another research paper posted on arXiv on nowrap|22 July 2008, titled "Exclusion of black hole disaster scenarios at the LHC", which summarizes proofs intended to rule out any possible black hole disaster at the LHC.Koch B, Bleicher M, Stöcker H (22 July 2008). " [http://arxiv.org/pdf/0807.3349v2 Exclusion of black hole disaster scenarios at the LHC] " (PDF). .]

Legal challenges

On nowrap|21 March 2008, a complaint requesting an injunction to halt the LHC's startup was filed by Walter L. Wagner and Luis Sancho against CERN and its American collaborators, the US Department of Energy, the National Science Foundation and the Fermi National Accelerator Laboratory, before the United States District Court for the District of Hawaii. [Overbye, Dennis (29 March 2008). " [http://www.nytimes.com/2008/03/29/science/29collider.html Asking a Judge to Save the World, and Maybe a Whole Lot More] ". "The New York Times".] " [http://dockets.justia.com/docket/court-hidce/case_no-1:2008cv00136/case_id-78717/ Sancho v. U.S. Department of Energy et al. (1:2008cv00136)] ". "Justia Federal District Court Filings & Dockets". 21 March 2008.] The plaintiffs demanded an injunction against the LHC's activation for 4 months after issuance of the LHC Safety Assessment Group's (LSAG) most recent safety documentation, and a permanent injunction until the LHC can be demonstrated to be reasonably safe within industry standards." [http://www.lhcdefense.org/lhc_legal.php Documentation submitted by plaintiff] ". LHCDefense.org.] The US Federal Court scheduled trial to begin nowrap|16 June 2009. [Boyle, Alan (16 June 2008). " [http://cosmiclog.msnbc.msn.com/archive/2008/06/16/1146317.aspx Doomsday under debate] ". "Cosmic Log". msnbc.com.]

The LSAG review, issued on nowrap|20 June 2008 after outside review, found "no basis for any concerns about the consequences of new particles or forms of matter that could possibly be produced by the LHC". The US Government, in response, called for summary dismissal of the suit against the government defendants as untimely due to the expiration of a six-year statute of limitations (since funding began by 1999 and has essentially been completed already), and also called the hazards claimed by the plaintiffs "overly speculative and not credible".Overbye, Dennis (27 June 2008). " [http://www.nytimes.com/2008/06/27/science/27collider.html Government Seeks Dismissal of End-of-World Suit Against Collider] ". "The New York Times".] The Hawaii District Court heard the government's motion to dismiss on nowrap|2 September 2008, and on, 26 September, the Court issued an order granting the motion to dismiss on the grounds that it had no jurisdiction over the LHC project. [Boyle, Alan (26 September 2008). " [http://cosmiclog.msnbc.msn.com/archive/2008/09/26/1457536.aspx Doomsday Lawsuit Dismissed] ". "Cosmic Log". msnbc.com.]

On nowrap|26 August 2008, a group of European citizens, led by a German biochemist Otto Rössler, filed a suit against CERN in the European Court of Human Rights, in Strasbourg, alleging the Large Hadron Collider poses grave risks for the safety of the 27 member states of the European Union and their citizens.Harrell, Eben (4 September 2008). " [http://www.time.com/time/health/article/0,8599,1838947,00.html?imw=Y Collider Triggers End-of-World Fears] ". "Time.com".] The request for an injunction was summarily rejected on 26 August, leaving the case that it violates the right to life still pending.Gray, Richard (9 September 2008). " [http://www.telegraph.co.uk/news/worldnews/europe/2650665/Legal-bid-to-stop-CERN-atom-smasher-from-destroying-the-world.html Legal bid to stop CERN atom smasher from destroying the world] ". "Telegraph.co.uk".]

References

External links

* [http://public.web.cern.ch/public/en/LHC/Safety-en.html "The safety of the LHC"] , CERN webpage.
* [http://cdsweb.cern.ch/record/1120625?ln=en "The LHC is safe" (video)] , talk by John Ellis at CERN, on 14 August 2008.