why_i_dont_have_a_girlfriend

Why I d on’t h ave a g irlfriend:An a pplication o f t he D rake E quation t o l ove i n t he U KPeter B ackus1The D rake e quation i s u sed t o e stimate t he n umber o f h ighly e volved civilizations t hat m ight e xist i n o ur g alaxy. T he e quation w as d eveloped i n 1961 by D r. F rank D rake a t t he N ational R adio A stronomy O bservatory i n G reen B ank, West V irginia.The e quation i s g enerally s pecified a s:G=R⋅fP ⋅ne⋅fl⋅fi⋅fe⋅Lwhere,G = T he n umber o f c ivilizations c apable o f i nterstellar c ommunicationR = T he r ate o f f ormation o f s tars c apable o f s upporting l ife (stars l ike o ur S un)n e = T he a verage n umber o f p lanets s imilar t o E arth p er p lanetary s ystemf l = T he f raction o f t he E arth-­‐like p lanets s upporting l ife o f a ny k indf i = T he f raction o f l ife-­‐supporting p lanets w here i ntelligent l ife d evelopsf c = T he f raction o f p lanets w ith i ntelligent l ife t hat a re c apable o f i nterstellar communication (those w hich h ave e lectromagnetic t echnology l ike r adio o r T V)L = T he l ength o f t ime s uch c ommunicating c ivilizations s urviveUsing t his e quation P rof D rake e stimated t hat 10,000 c ommunicative civilizations p robabilistically e xist i n t he M ilky W ay a lone. A stronomers e stimate that t here a re b etween 200 a nd 400 b illion s tars i n t he M ilky W ay. L et’s c all i t 300 b illion. T his m akes t he p robability o f a s tar c hosen a t r andom s upporting l ife capable o f i nterstellar c ommunication 3.333e-­‐08 o r 0.000003%.Another w ay t o t hink a bout t his i s t hat t his i s t he p robability o f t he c onditions necessary f or u s t o c ommunicate w ith a n a lien c ivilization b eing s atisfied. T hese seem l ike s lim o dds a t b est, b ut t he p robability i s p ositive (There i s a c hance!) and t his a pproach i s w idely a ccepted b y a stronomers (This i sn’t a s cience fiction!). T he i dea t hat t here c ould b e 10,000 c ivilizations t hat w e a re c apable o f communicating w ith i s v ery e xciting i ndeed.While e xtraterrestrial c ivilizations m ay b e r are, t here i s s omething t hat i s seemingly r arer s till: A g irlfriend. F or m e. W hat m ight t he a pproach e mployed i n1 I w ould l ike t o t hank I an L. J ohnson a nd a n a nonymous v olunteer r eferee f or c omments a nd suggestions c oncerning t his p aper. O thers h ave a pplied t he D rake e quation i n t he s ame w ay. S ee: ‘Singles i n S F’, ‘This A merican L ife, R aymond F rancis’s p aper a nd ‘The B ig B ang T heory’. L inks t othe e stimation o f t he n umber o f a lien c ivilizations t ell u s a bout t he n umber o fpotential g irlfriends f or m e? A s omewhat l ess s cientific q uestion, I a dmit, b ut o ne of s ubstantial p ersonal i mportance.The p arameters a re r e-­‐defined a s f ollows w ith t he v alues i n p arentheses:G = T he n umber o f p otential g irlfriends.One c an e asily s ubstitute b oyfriends i n h ere b ut a s I a m m ostly aheterosexual m ale I w ill f ocus o n t he s earch f or a g irlfriend.R = T he r ate o f f ormation o f p eople i n t he U K (i.e. p opulation g rowth).This i s a bout 150,000 p eople p er y ear o ver t he l ast 60 y ears.2f W = T he f raction o f p eople i n t he U K w ho a re w omen.See t he a bove c larification. (0.51)f L=The f raction o f w omen i n t he U K w ho l ive i n L ondon.I w ould l ike m y g irlfriend t o b e n earby s o t hat w e c an s ee e ach o ther. T hismakes i t e asier t o g et t o k now e ach o ther, a voids t he d ifficulties o f a l ong distance r elationship a nd s aves m e t he t rain f are. (0.13)f A = T he f raction o f t he w omen i n L ondon w ho a re a ge-­appropriate.I a m n early 31 y ears o ld (Thank y ou, I k now I d on’t l ook i t). I w ould l ikemy g irlfriend t o b e n ear m y o wn a ge. I d on’t w ant t o f eel o lder t han I a mby n ot b eing a ble t o k eep u p w ith a s pritely 20 y ear o ld, o r b ecause Ihaven’t r ead T wilight a nd I d on’t k now w ho t he J onas B rothers a re. N ordo I w ant t o f all p rey t o a v oracious c ougar o r t o b e r egaled w ith s tories o f the w ar. L ets s ay I a m l ooking f or a w oman b etween 24 a nd 34 y ears o f age. (0.20)f U = T he f raction o f a ge-­appropriate w omen i n L ondon w ith a u niversityeducation.I a m n ot t rying t o b e a n e litist o r a nything, b ut I w ould l ike m y g irlfriendto h ave a u niversity e ducation. I t hink w e w ould h ave m ore i n c ommonand I would l ike s omeone I c ould d iscuss m y w ork w ith s ometimes. Iknow t hat t here a re m any i ntelligent p eople w ho d on’t g o t o u niversity, s odon’t g et a ll r ighteously i ndignant. E veryone h as p references. H ow m anywomen o ut t here h ave d ated m en s horter t han t hemselves? I r est m ycase. (0.26)f B = T he f raction o f u niversity e ducated, a ge-­appropriate w omen i n L ondon who I f ind p hysically a ttractive.Physical a ttractiveness i s i mportant. I t i s o ften t he f irst t hing p eople notice a bout e ach o ther a nd i t m akes s ex e asier. N ot t hat m y p otential girlfriend n eed b e c onsidered a ttractive b y a nyone e lse, b ut i t i s important t hat I f ind h er a ttractive. T his i s a t ough p arameter t o estimate. L et’s b e g enerous a nd s ay I f ind 1 i n 20, o r 5% o f a ge-­‐appropriate w omen i n L ondon w ith a u niversity e ducation p hysically attractive. (0.05)L = T he l ength o f t ime i n y ears t hat I h ave b een a live t hus m aking a n encounter w ith a p otential g irlfriend p ossible.Good l ord, I a m o ld. (31)We c an s implify t he a bove s pecification b y r ecognizing t hat t he n umber o f p eople who h ave e ver l ived i n t he U K i s r elated t o t he p opulation g rowth r ate b yN =R (t )dt 0T ∫where T i s t he a ge o f t he U K. I f w e a ssume t hat R i s c onstant o ver t he p eriod T than N =R ⋅T . W hile t his s implification i s o ften u sed f or t he D rake E quation’s intended p urpose, i t i s n ot a g ood a ssumption w hen a dapting t he e quation f or our p urposes h ere. I nstead w e u se N *, t he p opulation o f t he U K a s o f 2007, w hereN *=60,975,000.3With t his s implification w e c an r e-­‐specify t he D rake e quation a s:G =N *⋅f W ⋅f L ⋅f A ⋅f U ⋅f B If w e p lug i n t he a bove v alues w e g et:G =60,975,000⋅0.51⋅0.13⋅0.20⋅0.26⋅0.05orG=10,510So, w hat t his m eans i s t hat t here a re 10,510 p eople i n t he U K t hat s atisfy t hese most b asic c riteria f or b eing m y g irlfriend. T hat i s 0.017% o f t he U K a nd 0.14%of L ondoners, w hich d oesn’t s eem s o b ad. O n a g iven n ight i n L ondon, t here i sgreater t han a 1 i n 1000 c hance t hat I w ill m eet a n a ttractive w oman b etween the a ges o f 24 a nd 34 w ith a u niversity d egree. O f c ourse t his d oes n ot t ake i ntoaccount t he f raction o f t hese w omen t hat w ill f ind m e a ttractive (depressingly low), t he f raction o f t hese w omen w ho w ill b e s ingle (falling w ith a ge) a nd, perhaps m ost i mportantly, t he f raction o f t hese w omen w ho I w ill g et a long w ith. Including s uch f actors w ould g reatly r educe t he a bove f igure o f 10,510. A r ough estimate p uts t he n umber o f p otential g irlfriends a ccounting f or t hese t hree additional c riteria (1 i n 20 o f t he w omen f ind m e a ttractive, h alf a re s ingle a nd I get a long w ith 1 i n 10) a t 26. T hat’s c orrect. T here a re 26 w omen i n t he U K w ith whom I m ight h ave a w onderful r elationship. S o, o n a g iven n ight o ut i n L ondon there i s a 0.00034% c hance o f m eeting o ne o f t hese s pecial p eople, a bout 100 times b etter t han f inding a n a lien c ivilization w e c an c ommunicate w ith. T hat’s a 1 i n 285,000 c hance. N ot g reat.Make o f t his w hat y ou w ill. I t m ight c heer y ou u p, i t m ight d epress y ou. I g uess i tdepends o n w hat y ou t hought y our c hances w ere b efore r eading t his.。