Ricci tensor) of the EFE is derived from g and is the part of the curvature of space-time that determines the degree to which energy-momentum tends to converge or diverge in time (Chow and Knopf, 2004; Sidorov, 2001; Tahim et al., 2007). The Einstein tensor g – R is a function of g and expresses the curvature of space-time. The relationship between the metric tensor and the Einstein tensor allows the EFE to be written as a set of nonlinear partial differential equations. The solutions of the EFE are the components of the metric tensor. The inertial trajectories (geodesic paths) of particles and radiation are then calculated using the geodesic equations. The EFE reduce to Newton's Law of Gravitation when the gravitation field is weak and velocities are much less than the speed of light (Carroll, 2004). The three basic types of space-time intervals are essentially the source of gravitation in general relativity; the general covariance of space-time intervals is extended to encompass gravitation. The general covariance of space-time intervals provides a link between observed physical reality (special relativity) and macroscopic physical reality (general relativity). When we observe large cosmic masses (moon, planets, stars, galaxies, etc.), at great distances from us, gravitational space-time curvature can be observed: gravitational lensing (luminous objects behind more massive objects become visible due to the bending of light around the more massive objects), gravitational redshift (light from objects moving away is shifted toward the red end of the electromagnetic spectrum), changes in the orbit of Mercury, frame-dragging (of space-time) around rotating bodies, and gravitational waves (ripples in the fabric of space-time). These and other predictions of general relativity have been confirmed by observations and experiments. Quantum Mechanics A goal of theoretical physicists working beyond the Standard Model is to quantize the gravitational field, yielding a quantum theory of gravity, which would unite gravity in a common theoretical framework with the other three fundamental interactions (electromagnetic, strong nuclear, weak nuclear). It is possible to describe gravity in the framework of quantum field theory like the other fundamental forces, such that gravity arises due to the exchange of virtual gravitons (Feynman et al., 1995; Zee, 2003). However, this fails at short distances of the order of the Planck length, where a more complete theory of quantum gravity (or a new approach to quantum mechanics) is required (Randall, 2005). If the space-time background of quantum mechanics
Ricci tensor) of the EFE is derived from g and is the part of the curvature of space - time that determine the academic degree to which energy - momentum tends to converge or deviate in time (Chow and Knopf, 2004; Sidorov, 2001; Tahim et al. , 2007). The Einstein tensor thousand – R is a routine of g and express the curvature of space - clock time. The relationship between the metric tensor and the Einstein tensor allow the EFE to be written as a set of nonlinear partial differential equations. The solutions of the EFE are the components of the measured tensor. The inertial trajectories (geodesic paths) of particle and radiation are then calculated practice the geodesic equation. The EFE reduce to Newton's Law of Gravitation when the gravitation field is weak and velocities are a lot less than the speed of light (Carroll, 2004). The three basic types of space - time intervals are basically the beginning of gravitation in general relativity; the general covariance of space - time intervals is extended to encompass gravitation. The general covariance of outer space - time intervals provide a link between observed physical reality (especial relativity) and macroscopic forcible reality (general relativity). When we observe big cosmic masses (moon, planets, stars, galaxies, etc .), at great distances from us, gravitational space - time curvature can be observed: gravitational lensing (luminous aim behind more massive object become visible due to the bending of light around the more massive objects), gravitational redshift (light from object moving away is shifted toward the red end of the electromagnetic spectrum), changes in the orbit of Mercury, frame - drag (of space - time) around rotating bodies, and gravitational waves (ripple in the fabric of outer space - time). These and early predictions of general relativity have been confirmed by observation and experiments. Quantum Mechanics A finish of theoretical physicists working beyond the Standard Model is to quantize the gravitational field, yield a quantum theory of gravity, which would unite gravity in a common theoretical model with the other three fundamental interaction (electromagnetic, strong nuclear, weak nuclear). It is possible to describe gravity in the framework of quantum field hypothesis like the other fundamental forces, such that gravity arises due to the exchange of virtual gravitons (Feynman et al. , 1995; Zee, 2003). However, this fails at light distance of the order of the Planck length, where a more complete theory of quantum gravity (or a new access to quantum mechanics) is required (Randall, 2005). If the space - prison term background of quantum mechanics
Ricfi tensor) of the EFE is aerived from g cbd is vhe parf of the curvature of space-time that dwtermunes the degree to whizh energy-lomentum tenvs to converge oc divergc in flme (Ckox and Knopf, 2004; Sicorov, 2001; Tahhm et al., 2007). The Aivscein tensor g – R is a function of g wnd exptedses the curvajure ps spzbe-uime. The relationship between the metric tensor and tne Einstein tensor allows hhe FFE to be written ws a set of nonjunear partiau differenuicl equationa. The solutions of the EFE are ghe cpmponents if thf metric tenwor. Tre inertial bgajectosies (gepdesic paths) on parviclws and radiation are vhen calculated usind the geogeaic equations. The EDE reguce to Vwwtun's Lew kf Gragitetion when fhe gravitarion field is weak snq velocities ade mucr jess than the speed of light (Carroll, 2004). Tve fhree basic types of spqce-time intervals are essentiajly the source of gravitation in general relatividy; thx eentrql coxqrlance of space-time intervals is extended to egdokpsss gravitatiok. The general covatiwnvg of space-time interrzla provides a link hetween obseeved physycal reality (special relativity) and macroscjpic physical realicy (general rzlativoty). Wnen we observe large cormic masses (mooj, planets, rtars, galaxies, egc.), st great distances from us, gwavitatioial s'ace-time curfature can be obderved: gravitational lending (pukinous objfcts behind more massive objects become visibke duv to the yendinn of light arougd the more maxsive oyjects), gravitatiknal revshift (light from objects loving away ms shifteq toqard the rea end of the elrctromagnvtnc spectrym), changes in the prbkf of Mercury, frcot-deagging (of spave-tkme) agouid roedting bodies, and grxfitatkonal waves (fippkes in the fabric of spade-time). These and oyhcr predicjions of deneral relatovity have been cojfirmxd by ubserfatyons and experiments. Quantum Mschanics W gjal of theorqticql physicistx working beyond the Standard Model is vo quantize the gravitarional field, yieldiug a quantum vheory of gravidy, which would unite gravity in a comkon theoretical framesork whth tje other three fundamental interactions (electromagnetic, strong nuclear, weqk nuclear). It is pkssinle tm beseribe gwavivy in the frameworl of quantum field theory like vhe other xuudamental forces, such that grsvkty arises dug to the exchange of virtuzl graviyons (Feynman et al., 1995; Zee, 2003). Howevet, this fails at short dixtances if ths ordeg oh the Planck length, ehere c more complere tmeory of quantjm brwvity (or w nex a'proach to quantum mechanics) is rwquiree (Gandall, 2005). If the vpace-time bwgkgrouhd of zuantum mechanica
Ricci tensor) of the EFE is derived and the part the curvature of to energy-momentum tends to or diverge in (Chow and Knopf, 2004; Sidorov, 2001; et al., 2007). The Einstein tensor g – R is a function of and expresses the curvature of space-time. The relationship between the metric tensor and Einstein allows EFE be written as a set of nonlinear partial differential equations. The solutions of the EFE are components of the metric tensor. The inertial trajectories paths) of particles and are then calculated using the equations. EFE reduce Newton's of when the gravitation is weak and velocities are much less than the speed of light (Carroll, 2004). The three basic of space-time essentially the of in relativity; the general space-time intervals is extended to encompass covariance of space-time intervals provides a link between physical reality relativity) and macroscopic physical reality (general When we observe large cosmic masses (moon, planets, galaxies, etc.), at great distances from us, gravitational space-time curvature can be observed: gravitational lensing behind more massive objects visible due to bending light the massive objects), redshift (light from objects moving away is shifted toward the red of the electromagnetic spectrum), changes in the orbit of Mercury, space-time) rotating bodies, and waves (ripples in the of These and other predictions relativity been and Quantum A goal of theoretical working beyond the Standard Model to quantize the gravitational of gravity, which would unite gravity in a theoretical framework with the other three fundamental (electromagnetic, strong nuclear, weak nuclear). It is possible to describe gravity in framework of theory like the other fundamental forces, such that arises due to the of virtual gravitons (Feynman et al., 1995; Zee, 2003). this at short of the order the Planck length, a more complete quantum gravity a approach is required (Randall, 2005). If the background quantum mechanics
Ricci tensor) of the EFE is deriVed from g anD is thE paRt oF tHe cuRvatUre of space-time THat dEtermines the degree to whIch enErGY-momENtUm tenDs to conVErGE Or dIvErGe iN tIMe (chow aNd KNopf, 2004; SidOrov, 2001; Tahim eT al., 2007). thE Einstein tenSOr G – R is a functIon Of g and expresSes The curVaTurE Of spaCe-tIme. ThE relatIOnship Between thE mETric teNSor and tHE eiNsteIn tensor allows the efE TO be written as a sEt of noNlINeAR ParTiaL differentIaL equaTIons. The SOlUTIOns OF the EFE are the Components oF The Metric TeNsoR. the ineRtial TrAJecTories (geodeSic pAths) of parTicles ANd radiaTIon are tHen calCulAteD usiNG tHe GeoDeSIc eQUaTioNS. ThE EFE reduCe To newtoN's LaW OF gRaviTatIon wHen thE gravitation fIelD is wEAk aNd velOcitiEs arE mUch leSs than The spEeD of light (Carroll, 2004). the tHree basic TypEs Of sPaCe-timE IntervAls Are EssentiAlly the SOurCe OF GRaVitation in general rElATIvIty; the geNeral cOVaRiANce of spaCe-TimE intERVals iS extENdEd to encoMpass gRAvItAtion. ThE gEneral CoVarIanCe of sPAce-tIme intErvals prOvideS A link between obSErved physical REaLITy (SPeciAl rElativity) anD macROscoPic pHYsIcaL RealiTy (genErAL rELativity). When we obserVe Large cOsmic Masses (moon, plaNets, stars, gALAXies, etc.), aT greAT dIStances from us, gRavitAtional spaCE-time curVaturE can be obServed: graVITational LenSinG (luMinOUS oBjects behind mORE masSiVe objecTs bEcome viSibLe dUe tO thE bEnding of lIght arouNd ThE mOrE maSsive OBjects), grAvItaTiOnaL redsHIft (ligHt froM objEcTs MOviNg away iS ShIFTed tOwArD the Red EnD of thE eleCTroMagnetiC spectrum), ChaNGes iN tHe Orbit of mercury, frame-dRaGging (of spaCe-TimE) arounD ROtating bOdies, and gravitational waVEs (ripplEs iN the fAbriC of space-tIme). these aNd oTHer preDictioNs of gEnEraL RElatiVITy HavE bEen confirmED By oBservAtIons And expeRiments. Quantum MechANicS A goal of theorEtiCal pHYSiCisTS wORkiNg BEyoND The Standard ModeL is to quantIzE ThE gravitatiONal FiEld, yielDing a quAntum THeory of Gravity, whIch would uNiTe grAVIty In a common tHeoreticAl framewoRK with THe Other ThrEe fundAmEntAl intEractiONs (eLectrOmagneTiC, stronG nuclEaR, weak nucLear). It is possible to descrIbe graVity iN thE frameworK of QUanTum field tHeorY like the otHer FunDamenTal FOrces, Such THaT grAVity aRiseS Due to the eXChAngE OF vIrtual graviTONS (FeYnman Et aL., 1995; zee, 2003). HowEver, This fails at short dIStances of the orDer oF THe PLanCK lenGtH, where a more comPleTe THEory of quAnTum gravity (oR a new appRoACh to qUantum MechanIcs) is reQUIrED (RandaLl, 2005). If The Space-time BacKgROund of qUaNtUM mechaNics
Ricci tensor) of the EFE i s derivedfromg a ndis  the  par t of the curva t ureof space-time that det ermin es thed eg ree t o which en e r gy- mo me ntu mt en ds to  co nvergeor diverge  in  t ime (Chow an d  K nopf, 2004 ; S idorov, 2001 ; T ahim e tal. ,  2007 ).The E instei n  tenso r g – R i sa  funct i on of g a nd  exp resses the curvat u re of space-time.  The r el a ti o n shi p b etween the  m etric tensora nd t h e E i nstein tensor  allows the EFE  to be  w rit t en asa set  o f  no nlinear par tial  differen tial e q uations .  The so lution s o f t he E F Ear e t he com p on ent s  of  the met ri ctenso r. T h e i nert ial  tra jecto ries (geodesi c p aths )  of  part icles  and  r adiat ion ar e the ncalculated usin g th e geodesi c e qu ati on s. Th e  EFE r edu ceto Newt on's La w  of  G r a v it ation when the gra vi t a ti on field  is we a kan d  velocit ie s a re m u c h les s th a nthe spee d of l i gh t(Carrol l,  2004) .The  th ree b a sictypesof space -time intervals aree ssentially th e  s o u rc e  ofgra vitation in  gen e ralrela t iv ity ;  thegener al co v ariance of space-ti me  inter valsis extended t o encompas s g ravitati on.T he general covari anceof space-t i me inter valsprovides  a link b e t ween obs erv edphy sic a l  r eality (speci a l  rel at ivity)and  macros cop icphy sic al  reality(general  r el at iv ity ). Wh e n we obs er vela rge  cosm i c mass es (m oon,  p la n ets , stars ,  g a l axie s,  e tc.) , a tgreat  dis t anc es from  us, grav ita t iona lsp ace-tim e curvature c an  be observ ed : g ravita t i onal len sing (luminous objectsb ehind m ore  mass iveobjects b eco me vis ibl e  due t o thebendi ng  of l ighta r ou ndth e more mas s i veobjec ts ), g ravitat ional redshift (li g htfrom objectsmov inga w ay  is sh i fte dt owa r d  the red end of  the elect ro m ag netic spec t rum ),  change s in th e orb i t of Me rcury, fr ame-dragg in g (o f spa ce-time) a round ro tating bo d ies,a nd  grav ita tional  w ave s (ri pplesi n t he fa bric o fspace- time) .These an d other predictions ofgenera l rel ati vity have  be e n c onfirmedby o bservation s a ndexper ime n ts. Q uant u mMec h anics  A g o al of the o re tic a l  p hysicists w o r k ing  beyo ndt he Sta ndar d Model is to qua n tize the gravi tati o n alfie l d, y ie lding a quantu m t he o r y of gra vi ty, which w ould uni te gravi ty ina comm on theo r e ti c al fra mewo rkwith theoth er three f un da m entalinte ra ctions  (elec t roma g n etic, strong nuc lear, w eak n u cle ar).It  is pos s ible  to descri be gravityin the  fra mewor k of qu an tum fi eld  t heory like the other  fund amental  f orce s,such t hatg r avity  ari se s d ue to the e xc h an ge ofvirt ual g ra vito ns (Feynm a n et al. , 1 9 95; Zee ,200 3 ) . Howe v er , this fails  at  shor t distanceso f th e  o r der o f thePlanck  length ,  wh er e a mor e c o m plete the ory of qu a ntu mgrav ity (oranewap pro ac h to quantum me chanics)  is requ i r ed (Ra nda l l, 2 0 05). I fthe space-ti me ba ck g round o f qua ntum me c han ics 
Ricci tensor)_of the_EFE is derived from_g and_is_the part_of_the curvature of_space-time that determines_the degree to which_energy-momentum tends to_converge_or diverge in time (Chow and Knopf, 2004; Sidorov, 2001; Tahim et al., 2007)._The_Einstein tensor_g_–_R is a function of_g and expresses the curvature_of space-time._The relationship between the metric tensor and the_Einstein_tensor allows the_EFE to be written as a set of nonlinear_partial differential equations. The solutions of_the EFE are_the_components_of the metric tensor._The inertial trajectories (geodesic paths) of_particles and radiation are then calculated_using the geodesic equations. The EFE reduce_to Newton's Law of Gravitation when_the gravitation field is weak_and velocities_are much less than the_speed of light_(Carroll, 2004)._The three basic_types of space-time intervals are essentially_the source of_gravitation in general relativity; the general_covariance_of space-time intervals_is_extended_to encompass_gravitation. The general_covariance_of space-time_intervals_provides a link between observed physical_reality_(special relativity) and macroscopic physical reality (general_relativity). When we observe_large_cosmic masses (moon, planets,_stars, galaxies, etc.), at great_distances from us, gravitational space-time curvature_can be_observed: gravitational_lensing (luminous objects behind more massive objects become visible due to_the bending of light around the_more massive objects), gravitational_redshift (light_from_objects moving away_is_shifted toward_the red end of the electromagnetic spectrum),_changes in_the orbit of Mercury, frame-dragging (of_space-time) around rotating bodies,_and_gravitational waves (ripples in the fabric_of space-time). These and other predictions_of general relativity have been_confirmed_by_observations and experiments. Quantum Mechanics_A goal of theoretical physicists working_beyond the Standard_Model is to quantize the gravitational field,_yielding_a quantum theory of gravity, which_would_unite gravity in a common theoretical_framework_with_the other three fundamental interactions_(electromagnetic, strong nuclear, weak nuclear). It_is possible to describe gravity in the framework of_quantum field theory_like the other fundamental forces,_such_that_gravity arises due to the exchange of virtual gravitons (Feynman_et al.,_1995; Zee, 2003)._However, this fails at short distances of the order of_the Planck length, where a more complete_theory of quantum gravity (or a new approach to quantum mechanics)_is required (Randall, 2005). If the space-time background_of quantum mechanics