Purpose Of LHCPhysicistshope that the LHC will help answer some of thefundamental open questionsin physics, concerning the basic laws governing the interactions and forces among theelementary objects, the deep structure of space and time, and in particular the interrelation betweenquantum mechanicsandgeneral relativity, where current theories and knowledge are unclear or break down altogether. Data is also needed from high energy particle experiments to suggest which versions of current scientific models are more likely to be correct in particular to choose between theStandard ModelandHiggsless modelsand to validate their predictions and allow further theoretical development. Many theorists expect new physics beyond the Standard Model to emerge at the TeV energy level, as the Standard Model appears to be unsatisfactory. Issues possibly to be explored by LHC collisions include:[16][17] Are themassesofelementary particlesactually generated by theHiggs mechanismviaelectroweaksymmetry breaking?[18]It is expected that the collider will either demonstrate or rule out the existence of the elusiveHiggs boson, thereby allowing physicists to consider whether the Standard Model or its Higgsless alternatives are more likely to be correct.[19][20][21] Issupersymmetry, anextension of the Standard ModelandPoincar symmetry, realized in nature, implying that all known particles havesupersymmetric partners?[22][23][24] Are thereextra dimensions,[25]as predicted by various models based onstring theory, and can we detect them?[26] What is the nature of thedark matterthat appears to account for 27% of the mass-energy of theuniverse?Other open questions that may be explored using high energy particle collisions: It is already known thatelectromagnetismand theweak nuclear forceare different manifestations of a single force called the electroweak force. The LHC may clarify whether the electroweak force and thestrong nuclear forceare similarly just different manifestations of one universal unified force, as predicted by variousGrand Unification Theories. Why is the fourth fundamental force (gravity) so many orders of magnitude weaker than the other threefundamental forces? See alsoHierarchy problem. Are there additional sources ofquarkflavourmixing, beyond those already present within theStandard Model? Why are there apparent violations of thesymmetrybetween matter andantimatter? See alsoCP violation. What are the nature and properties ofquarkgluon plasma, believed to have existed in theearly universeand in certaincompactandstrangeastronomical objects today? This will be investigated byheavy ion collisions, mainly inALICE, but also inCMSandATLAS. Findings published in 2012 confirmed the phenomenon ofjet quenchingin heavy-ion collisions, and was first observed in 2010.[27][28][29]