by Rigorous Intuition » Thu Sep 07, 2006 11:14 pm
people both inside and outside of the physics community have voiced concern that the LHC might trigger one of several theoretical disasters capable of destroying the Earth or even the entire universe. These include:<br><br> * Creation of a stable black hole[7]<br> * Creation of strange matter that is more stable than ordinary matter<br> * Creation of magnetic monopoles that could catalyze proton decay<br> * Triggering a transition into a different quantum mechanical vacuum (see <!--EZCODE BOLD START--><strong>False vacuum</strong><!--EZCODE BOLD END-->)<br><br>CERN performed a study to investigate whether such dangerous events as micro black holes, strangelets, or magnetic monopoles could occur.[8] The report concluded, "We find no basis for any conceivable threat." For instance, it is not possible to produce microscopic black holes unless certain untested theories are correct. Even if they are produced, they are expected to be harmless due to the Hawking radiation process. Perhaps the strongest argument for the safety of colliders such as the LHC comes from the simple fact that cosmic rays of much higher energies than the LHC can produce have been bombarding the Earth, Moon and other objects in the solar system for billions of years with no such effects.<br><br>However, some people remain concerned about the safety of the LHC. As with any new and untested experiment, it is not possible to say with utter certainty what will happen. John Nelson at Birmingham University stated of RHIC that "it is astonishingly unlikely that there is any risk - but I could not prove it." <!--EZCODE LINK START--><a href="http://en.wikipedia.org/wiki/Large_Hadron_Collider#Safety_concerns">en.wikipedia.org</a><!--EZCODE LINK END--><br><br><!--EZCODE LINK START--><a href="http://en.wikipedia.org/wiki/False_vacuum">False Vacuum</a><!--EZCODE LINK END-->:<br><br>The possibility that we are living in a false vacuum has never been a cheering one to contemplate. Vacuum decay is the ultimate ecological catastrophe; in the new vacuum there are new constants of nature; after vacuum decay, not only is life as we know it impossible, so is chemistry as we know it. However, one could always draw stoic comfort from the possibility that perhaps in the course of time the new vacuum would sustain, if not life as we know it, at least some structures capable of knowing joy. This possibility has now been eliminated.[7]<br><br>The possibility that we are living in a false vacuum has been considered. If a bubble of lower energy vacuum were nucleated, it would approach at nearly the speed of light and destroy the Earth instantaneously, without any forewarning. Thus, this vacuum metastability disaster is a theoretical doomsday scenario. This was used in a science-fiction story by Geoffrey A. Landis in 1988 [8].<br><br>One scenario is that, rather than quantum tunneling, a particle accelerator, which produce very high energies in a very small area, creating sufficiently high energy density as to penetrate the barrier and stimulate the decay of the false vacuum to the lower energy vacuum. Hut and Rees,[9] however, have determined that because we had observed cosmic ray collisions at much higher energies than those produced in terrestrial particle accelerators, that these experiments will not, at least for the foreseeable future, pose a threat to our vacuum. Particle accelerations have reached energies of only approximately four thousand billion electron volts (4 ×103 GeV). Cosmic ray collisions have been observed at energies of 1011 GeV, the so-called Greisen-Zatsepin-Kuzmin limit. John Leslie has argued[1<!--EZCODE EMOTICON START 0] --><img src=http://www.ezboard.com/images/emoticons/alien.gif ALT="0]"><!--EZCODE EMOTICON END--> that if present trends continue, particle accelerators will exceed the energy given off in cosmic ray collisions by the year 2150.<br><br>This disaster is contingent on our living in a metastable vacuum, an issue which is far from resolved (see [11]). Worries about the vacuum metastability disaster are reminiscent of the controversy about turning the Relativistic Heavy Ion Collider on.<br> <p></p><i></i>