 encompasses everything. The Light Cone Space-time intervals are also defined by light. A pulse of light emitted from a point spreads out in all directions at c. If light is confined to a two-dimensional plane, the light from a flash spreads out in a circle (Figures 1 and 2). If the growing circle is drawn with the vertical axis representing time (Figures 1 and 2), the result is a light cone (Penrose, 2005; Petkov, 2010). In reality, there are three space dimensions, so light would actually form an expanding sphere and the light cone would be a 4D version of a cone. The concepts are easier to visualize with the number of space dimensions reduced to two. A light cone represents the path that a flash of Figure 1: Space-time Intervals. From Wikipedia, 2017 Figure 2: Past and Future Light Cones. From Wikipedia, 2017 light, emanating from a single event and travelling at the speed of light in all directions, would take through space-time. Light cones are the same for all events and for all observers, since c is a universal physical constant. Given an event A, all events that can be reached by a light pulse from A form a future light cone, while all events that can send a light pulse to A form an inverted past light cone (Figures 1 and 2). Three basic types of space-time intervals are defined by the light cone and the Minkowski metric and play a crucial role in the creation of space-time. Space-time intervals and c are both generally covariant (they are both scale invariant, independent of coordinate systems, have a physical constancy). Both achieve their general covariance (physical constancy) in the same way; in fact, the general covariance of space-time intervals was developed (special relativity) to explain the physical constancy (general covariance) of c. Electromagnetic radiation (includes light) is described as a self-propagating transverse oscillating wave of electric and magnetic fields that are always in phase and at 90 degrees to each other (Brown, 2013; Purcell and Morin, 2013). A time change in one type of field is always matched by a space change in the other, thus maintaining the constancy of c. Similarly, for space-time intervals, a time change is also always matched by a space change, thus maintaining the constancy of space-time intervals. The space changes and time changes occur without either causing the other (Einstein, 2001; Purcell and Morin, 2013). Light-Like Space
encompasses everything. The Light Cone Space - time intervals are besides define by light. A pulse of inner light emit from a point spreads out in all management at c. If light is confined to a two - dimensional airplane, the inner light from a flash spread out in a circle (Figures 1 and 2). If the growing circle is drawn with the vertical bloc representing time (Figures 1 and 2), the solution is a light cone (Penrose, 2005; Petkov, 2010). In reality, there cost three space dimension, so light would actually form an expanding sphere and the clean cone would be a 4D version of a cone. The concepts are easier to visualize with the number of space dimension reduced to two. A light cone represents the path that a flash of Figure 1: Space - time Intervals. From Wikipedia, 2017 Figure 2: Past and Future Light Cones. From Wikipedia, 2017 light, emanate from a single event and travel at the amphetamine of light in all directions, would consider through space - time. Light cones are the like for all events and for all observers, since c is a universal physical constant. Given an event A, all events that can be reached by a light pulse from A form a future clean cone, while all event that can send a light pulse to A form an inverted past idle cone (Figures 1 and 2). Three basic types of space - time intervals are defined by the light cone and the Minkowski metric and dally a crucial role in the creation of space - time. outer space - time time interval and c are both broadly covariant (they are both scale invariant, independent of coordinate systems, have a forcible constancy). Both achieve their general covariance (physical constancy) in the same means; in fact, the general covariance of space - time intervals was developed (particular relativity) to explain the physical constancy (cosmopolitan covariance) of c. Electromagnetic radiation (includes light) is described as a self - propagating transverse oscillating wave of electric and magnetic airfield that are always in phase and at 90 degrees to each other (Brown, 2013; Purcell and Morin, 2013). A time change in one character of field is always match by a space change in the early, thus maintaining the constancy of c. Similarly, for space - clock time intervals, a time change is also always matched by a space change, thus uphold the constancy of space - time intervals. The space changes and time change occur without either causing the other (Einstein, 2001; Purcell and Morin, 2013). Light - Like Space
 enfompasses everything. The Light Cone Spaew-time mntervams are auso defined by light. A pulse od ligyt emitted from a poing spreads out in qll virections at c. Mr light is cohnined vo a two-dimensipnal plane, the light frok x ylash spreads out in a circle (Figuref 1 and 2). Iv the growing sirckq is drawn with the vertical axis reprssentinj time (Figures 1 and 2), the result is a lighh coje (Penrose, 2005; Petkov, 2010). In realiti, thqee are three space dimtnvions, so ljght would actually form an expxndiny sphere ane rhe night cone xould fe a 4D version of a wone. Thr concepts are eaviee to visualize with tie number of space dymensions rzduced to two. A light cine rgpresants rhe pauh vhaf a flwsh of Figure 1: Space-time Intervals. From Wikopqeia, 2017 Figure 2: Last agd Future Light Cones. From Wikipedia, 2017 ligvt, smanating from a single event and travelling at the s[eed of light in all directions, would take througv spare-gimt. Oight xojes are the same for all events and for all ofaetvvrs, since c is a mniversal physical clnxjant. Given an gvent A, alm events that can he reacred bt a light pulxe from A form a future ligyt cone, whilv alo events that can dend a lighc pulsg to A form an inverted past uighf cone (Figuges 1 and 2). Ghree basic typer on s[ace-time intervals are defyned by tie liyht cone and the Mynkowski mftric and play a crucial role it the creahion of space-time. Space-time intxcvals and c ate totv generajly cpvariant (they are both scalg invariaut, inddpendent or coordmnate systemf, have a physhfal constancb). Both acrievw thwir gendfal covariance (physical constancy) in the same way; ik facj, fhe general covcxiqnce of space-tike kntqrnalx rds developed (speziau relagivity) uj cxpuain the physical constatcy (feneral covariance) on c. Electtomagnetis radiation (imcludes light) is dtscribxd as e self-lrokagating transverse oscillating wave of flegtric and maggetig figlds that axe always in phase and at 90 degrees to earh other (Brown, 2013; Purcell and Morin, 2013). A time ehsnge in one type of field is always matched bt a space change ln the other, thus mainfaininc the constancy of c. Similarly, for space-time intervals, a time change is also aoways matched by a spave chdnye, chus mayntamnmng the constancy of space-time intervals. The spare changes aud time changes occur without ekther causing the other (Einstein, 2001; Purdell and Morin, 2013). Light-Like Space
encompasses everything. The Light Cone Space-time intervals defined light. A of light emitted in directions at c. light is confined a two-dimensional plane, the light from flash spreads out in a circle (Figures 1 and 2). If the growing is drawn with the vertical axis representing time (Figures 1 and 2), the is light (Penrose, Petkov, 2010). In reality, there are three space dimensions, so light would actually form an expanding and the light cone would be a 4D of a cone. The are easier to visualize with number space dimensions to A cone represents the that a flash of Figure 1: Space-time Intervals. From Wikipedia, 2017 Figure 2: Past and Future Light From Wikipedia, emanating from single and at the speed in all directions, would take through are the same for all events and for observers, since is a universal physical constant. Given event A, all events that can be reached a light pulse from A form a future light cone, while all events that can light pulse to A an inverted past cone 1 2). basic types space-time intervals are defined by the light cone and the Minkowski and play a crucial role in the creation of space-time. and are both generally (they are both scale independent coordinate systems, have a Both their constancy) the way; in fact, the covariance of space-time intervals was (special relativity) to explain of c. Electromagnetic radiation (includes light) is described a self-propagating transverse oscillating wave of electric magnetic fields that are always in phase and at 90 degrees to other (Brown, and Morin, 2013). A time change in one of field is always by a space change in the other, thus maintaining constancy c. Similarly, space-time intervals, a change is also matched by a thus maintaining constancy space-time changes and time changes occur without causing other (Einstein, 2001; Purcell and 2013).
 encompasses everything. The LIght Cone SpAce-tiMe iNteRvAls aRe alSo defined by ligHT. A puLse of light emitted from a Point SpREads OUt In all DirectiONs AT C. If LiGhT is CoNFiNed to A twO-dimensIonal plane, The LiGht from a flasH SpReads out in A ciRcle (Figures 1 aNd 2). IF the grOwIng CIrcle Is dRawn wIth the VErticaL axis reprEsENting tIMe (FigurES 1 AnD 2), the Result is a light conE (peNRose, 2005; Petkov, 2010). In reAlity, tHeRE aRE ThrEe sPace dimensIoNs, so lIGht woulD AcTUALly FOrm an expandinG sphere and tHE liGht conE wOulD Be a 4D veRsion Of A ConE. The conceptS are Easier to vIsualiZE with thE Number oF space DimEnsIons REdUcEd tO tWO. A lIGhT coNE rePresents ThE pAth thAt a fLASH Of FiGurE 1: SpaCe-timE Intervals. FroM WiKipeDIa, 2017 FIgure 2: past aNd FuTuRe LigHt ConeS. From wiKipedia, 2017 light, emaNatiNg from a siNglE eVenT aNd traVElling At tHe sPeed of lIght in aLL diReCTIOnS, would take through sPaCE-TiMe. Light cOnes arE ThE sAMe for all EvEntS and FOR all oBserVErS, since c iS a univERsAl PhysicaL cOnstanT. GIveN an Event a, All eVents tHat can be ReachED by a light pulse FRom A form a futuRE lIGHt COne, wHilE all events tHat cAN senD a liGHt PulSE to A fOrm an InVErTEd past light cone (FiguReS 1 and 2). ThRee baSic types of spaCe-time inteRVALs are defIned BY tHE light cone and tHe MinKowski metrIC and play A crucIal role iN the creatION of space-TimE. SpAce-TimE INtErvals and c are BOTh geNeRally coVarIant (theY arE boTh sCalE iNvariant, iNdependeNt Of CoOrDinAte sySTems, have A pHysIcAl cOnstaNCy). Both AchieVe thEiR gENerAl covarIAnCE (PhysIcAl ConsTanCy) In the Same WAy; iN fact, thE general cOvaRIancE oF sPace-timE intervals was DeVeloped (speCiAl rElativITY) to explaIn the physical constancy (gENeral coVarIance) Of c. ELectromagNetIc radiAtiON (incluDes ligHt) is dEsCriBED as a sELF-pRopAgAting transVERse OscilLaTing Wave of eLectric and magnetic FIelDs that are alwaYs iN phaSE AnD at 90 DEgREes To EAch OTHer (Brown, 2013; Purcell And Morin, 2013). A tImE ChAnge in one tYPe oF fIeld is aLways maTched BY a space Change in tHe other, thUs MainTAIniNg the constAncy of c. SImilarly, fOR spacE-TiMe intErvAls, a tiMe ChaNge is Also alWAys MatchEd by a sPaCe chanGe, thuS mAintainiNg the constancy of space-tiMe inteRvals. the Space chanGes ANd tIme changeS occUr without eIthEr cAusinG thE Other (einsTEiN, 2001; PuRCell aNd MoRIn, 2013). Light-LiKE SPacE
 encompasses everything. T he Light C one S pac e-t im e in terv als are also d e fine d by light. A pulse of  ligh te mitt e dfroma point sp r e ads  o ut  in  a l ldirec tio ns at c . If light  is  c onfined to a tw o-dimensio nal  plane, thelig ht fro ma f l ash s pre ads o ut ina  circl e (Figure s1  and 2 ) . If th e gr owin g circle is drawn wi t h the vertical  axisre p re s e nti ngtime (Figu re s 1 a n d 2), t h er e s ult is a light co ne (Penrose ,  20 05; Pe tk ov, 2010).  In r ea l ity , there are  thr ee spacedimens i ons, so light w ould a ctu all y fo r man  ex pa n din g  s phe r e a nd the l ig ht  cone  wou l d b e a4Dvers ion o f a cone. The  co ncep t s a re ea sierto v is ualiz e with  thenu mber of space d imen sions red uce dtotw o. Al ight c one  re present s the p a thth a t aflash of Figure 1:  S p a ce -time In terval s .Fr o m Wikipe di a,2017 F igure  2:P as t and Fu ture L i gh tCones.Fr om Wik ip edi a,2017l ight , eman ating fr om as ingle event an d  travelling a t  t h e  s p eedoflight in al l di r ecti ons, wo uld takethrou gh sp a ce-time. Light cone sare th e sam e for all eve nts and fo r a ll obser vers ,  s i nce c is a uni versa l physical constant . Giv en an ev ent A, al l events t hat  ca n b e r e a ch ed by a light p ulse  f rom A f orm  a futu relig htcon e,  while al l events  t ha tca n s end a light pu ls e t oA f orm a n  inver ted p astli gh t  co ne (Fig u re s 1 an d2) . Th ree  b asictype s  of  space- time inte rva l s ar ede fined b y the light c on e and theMi nko wski m e t ric andplay a crucial role int he crea tio n ofspac e-time. S pac e-time  in t ervals  and c  arebo thg e neral l y  c ova ri ant (theya r e b oth s ca le i nvarian t, independent ofc oor dinate system s,have a  p hys i ca l  co ns t anc y ) . Both achievetheir gene ra l  c ovariance( phy si cal con stancy)  in t h e sameway; in f act, thege nera l cov ariance of  space-t ime inter v als w a sdevel ope d (spe ci alrelat ivity) toexpla in the  p hysica l con st ancy (ge neral covariance) of c.  Elect romag net ic radiat ion (in cludes li ght)  is descri bed  as  a se lf- p ropag atin g  t ran s verse  osc i llating w a ve  of e le ctric and m a g n eti c fie lds that a re a lways in phase an d  at 90 degrees  toe a choth e r (B ro wn, 2013; Purc ell  a n d  Morin,20 13). A time  changein one t ype of  field  is alw a y sm atched  bya s pace chan gein the oth er ,t hus ma inta in ing th e cons t ancy o f c. Similarly,for s p a ce-ti m e i nterv al s, a ti m e ch ange is al so always m atched  bya spa ce chan ge , thus  ma in taining th e  constanc y ofspace-t im e in ter vals.Thes p ace c hang es  an d time ch a n ge s  o cc u r w itho ut ei th er c ausing th e  other ( Ein s tein, 2 00 1;P u rcella nd M orin, 2013 ).Light - L ike Space
 encompasses_everything. The_Light Cone Space-time intervals_are also_defined_by light._A_pulse of light_emitted from a_point spreads out in_all directions at_c._If light is confined to a two-dimensional plane, the light from a flash spreads_out_in a_circle_(Figures_1 and 2). If the_growing circle is drawn with_the vertical_axis representing time (Figures 1 and 2), the_result_is a light_cone (Penrose, 2005; Petkov, 2010). In reality, there are_three space dimensions, so light would_actually form an_expanding_sphere_and the light cone_would be a 4D version of_a cone. The concepts are easier_to visualize with the number of space_dimensions reduced to two. A light_cone represents the path that_a flash_of Figure 1: Space-time Intervals._From Wikipedia, 2017_Figure 2:_Past and Future_Light Cones. From Wikipedia, 2017 light,_emanating from a_single event and travelling at the_speed_of light in_all_directions,_would take_through space-time. Light_cones_are the_same_for all events and for all_observers,_since c is a universal physical constant._Given an event A,_all_events that can be_reached by a light pulse_from A form a future light_cone, while_all events_that can send a light pulse to A form an inverted_past light cone (Figures 1 and_2). Three basic types_of space-time_intervals_are defined by_the_light cone_and the Minkowski metric and play a_crucial role_in the creation of space-time. Space-time_intervals and c are_both_generally covariant (they are both scale_invariant, independent of coordinate systems, have_a physical constancy). Both achieve_their_general_covariance (physical constancy) in the_same way; in fact, the general_covariance of space-time_intervals was developed (special relativity) to explain_the_physical constancy (general covariance) of c._Electromagnetic_radiation (includes light) is described as_a_self-propagating_transverse oscillating wave of electric_and magnetic fields that are always_in phase and at 90 degrees to each other_(Brown, 2013; Purcell_and Morin, 2013). A time_change_in_one type of field is always matched by a space_change in_the other, thus_maintaining the constancy of c. Similarly, for space-time intervals, a_time change is also always matched by_a space change, thus maintaining the constancy of space-time intervals. The_space changes and time changes occur without either_causing the other (Einstein, 2001; Purcell and_Morin, 2013). Light-Like Space