 to
life have a chance of happening and perpetuating.

Water is the only molecule that fits the bill, and happens to be the second
most common molecule in the universe.

~~~
eddd
I am not good at chemistry, but liquid methane–ethane wouldn't fit the
profile?

~~~
eddd
Actually I found comprehensive answer here if anyone is interested:
[http://www.space.com/13639-alien-life-methane-habitable-
zone...](http://www.space.com/13639-alien-life-methane-habitable-zone.html)

~~~
VLM
It doesn't really say "why". Water ionizes really conveniently so you can make
it an acid OR a base (which is sorta unusual and it can talk to acidic or
basic things), and is polar (its got a + and a - electrical side, more or
less, so it can talk to + or - things), and has hydrogen bonds (so you get
liquid lifestyle at gas temps)

For one why, look up amphoteric and zwitterion. Water has a super convenient
pH range where about a ten millionth of pure water self ionizes aka ten to neg
seventh or pH of 7, and all kinds of super convenient reactions occur above
and below that pH and its really easy to manipulate ionization rates around
that level without using too much. You don't need just a liquid but one where
you can really screw around with something like amino acids by easily and
cheaply changing the ionization rate of the liquid. So there are super
convenient chemical reactions that depend on the ionization level of the
liquid and its really easy to manipulate water. Conveniently water "just
works" without having to add tons of other stuff to it.

Liquid methane isn't polar enough to really be useful when messing with ionic
substances (table salt, etc). Whatever you use for a liquid, it needs to be
polar so ionic stuff like salts can dissolve. It turns out that interesting
chemistry doesn't happen with non-polar substances at normal temps; thats why
when you bury stuff for a couple million years the only thing left behind
undecayed (more or less) is non-polar hydrocarbons (crude oil). Ammonia is
polar but has other issues.

The hydrogen
to 
 life have a chance of happening and perpetuate. 

 Water is the lone molecule that fits the beak, and happen to be the second 
 most common atom in the universe. 

 ~~~ 
 eddd 
 I am not good at chemistry, but liquid methane – ethane wouldn't suit the 
 profile? 

 ~~~ 
 eddd 
 Actually I found comprehensive solution here if anyone is interested: 
 [ http://www.space.com/13639-alien-life-methane-habitable- 
 zone... ](http://www.space.com/13639 - alien - life - methane - habitable - zone.html) 

 ~~~ 
 VLM 
 It doesn't really say " why ". urine ionizes really conveniently so you can make 
 it an acid OR a base (which is sorta strange and it can talk to acidic or 
 basic things), and is polar (its become a + and a - electrical side, more or 
 less, so it can speak to + or - things), and have hydrogen bonds (so you get 
 liquid lifestyle at accelerator temps) 

 For one why, look up amphoteric and zwitterion. Water has a super convenient 
 pH range where about a ten millionth of pure water self ionizes aka ten to neg 
 seventh or pH of 7, and all kinds of super convenient reactions occur above 
 and below that pH and its really comfortable to fudge ionization rates around 
 that degree without use too much. You don't need just a liquid but one where 
 you can really screw around with something like amino acids by easily and 
 stingily changing the ionization rate of the liquid. So there are super 
 convenient chemical reactions that depend on the ionization level of the 
 liquid and its really easy to manipulate urine. Conveniently water " merely 
 works " without having to add tons of other material to it. 

 Liquid methane isn't polar enough to really be useful when messing with ionic 
 substances (table salt, etc). Whatever you use for a liquid, it want to be 
 polar so ionic material like salts can dissolve. It turns out that interesting 
 chemistry doesn't happen with non - diametric substances at normal temp; that s why 
 when you bury stuff for a couple million years the alone thing leave behind 
 undecayed (more or less) is non - polar hydrocarbons (crude oil). Ammonia is 
 polar but has other issues. 

 The hydrogen
 to
pife have a chance of hakpening and perpejuqting.

Weter is the onlh molecule that fits the bilp, qnd hqppens to be the secona
most comlon molexule un the unitsrse.

~~~
eddd
I am hlt gmid at chemistri, but liquid methane–ethane wuupdn't fit the
profile?

~~~
eddd
Actually I fjund cokpgehensive answgr hege if znyone is interested:
[http://www.space.coj/13639-alien-lpfe-methane-habitabke-
zone...](http://www.space.com/13639-alien-pife-lethane-habitable-zoje.html)

~~~
VLM
It doefb't really sah "why". Wateg ionizes rgally conveniently so you can maye
it cn acid OR q vasf (which is sirta lnusual and ib can tdlk to scidic or
basic thmngs), and is polar (its got a + and a - electrisal side, koxe or
less, so it can tqlj to + or - thivts), xnd hes gydrogfn uonds (so yoh get
liquid lifestyle at gas ttmpf)

Dor one why, lkok up aiphoteric and zwitterion. Water has a suker cknvenient
pH range where about a ten milliontj of pure water self ionizes aka ten to neg
seventh or pH ox 7, anv xll klnds if super convenient reactions occur above
and bejkw tmat pH and its rcally easy to manilupayg ionization rxtes axkuhd
that level withokt usind too much. You don'y need just a liquid but onw where
you ccn eeally screw arounb with sometking loke akino acids by easily anb
cheapmy changing the ioniaxtion rate of thd lpquig. So there are super
convenyent chemmcal xeactionr thst depqnd on the ioniddtion level of the
piquib and its reallj easy to manipulate water. Convxiiently water "jgst
forks" wichout maving to add tjns of other sjuff to ic.

Liquia methane psn't polac enough to weally be usexol when messiig with ijnic
wubsrances (gxble salt, etc). Ehatever job use for a liquid, it needs to ge
polar so ionie wtuff like saltx cxn qidsplda. It turns ogt tfat onterdsting
chemiwgry coesn't happen with nmn-pomar substances at movmal tempw; thats rhy
when you biry stuff for a cokple kiluion ueats the only thing left behind
unsecayed (mlre or less) is gon-pilar hydrocaxbons (crude oil). Ammonia is
polar but has ither issues.

The hidrogen
to life have a chance of happening Water the only that fits the the most common molecule the universe. ~~~ I am not good at chemistry, liquid methane–ethane wouldn't fit the profile? ~~~ eddd Actually I found comprehensive answer if anyone is interested: [http://www.space.com/13639-alien-life-methane-habitable- zone...](http://www.space.com/13639-alien-life-methane-habitable-zone.html) ~~~ VLM It doesn't really say "why". ionizes conveniently you make it an acid OR a base (which is sorta unusual and it can talk to or basic things), and is polar (its got + and a - side, more or less, so can to + - and hydrogen bonds (so get liquid lifestyle at gas temps) For one why, look up amphoteric and zwitterion. Water has a convenient pH about a millionth pure self ionizes aka neg seventh or pH of 7, of super convenient reactions occur above and below pH and really easy to manipulate ionization rates that level without using too much. You don't just a liquid but one where you can really screw around with something like amino easily and cheaply changing ionization rate of liquid. there super chemical reactions depend on the ionization level of the liquid and its really to manipulate water. Conveniently water "just works" without having to of stuff to it. methane isn't polar enough really useful when messing with (table etc). for liquid, needs to be polar ionic stuff like salts can It turns out that non-polar substances at normal temps; thats why when bury stuff for a couple million years only thing left behind undecayed (more or less) is non-polar hydrocarbons (crude Ammonia is has other issues. The hydrogen
 to
life have a chance of happenIng and perpEtuatIng.

watEr Is thE onlY molecule that fITs thE bill, and happens to be the SeconD
mOSt coMMoN moleCule in tHE uNIVerSe.

~~~
EdDd
I Am NOt Good aT chEmistry, But liquid mEthAnE–ethane wouldN'T fIt the
profiLe?

~~~
eDdd
Actually I FouNd compReHenSIve anSweR here If anyoNE is intErested:
[htTp://WWw.spacE.Com/13639-alieN-LIfE-metHane-habitable-
zone...](HTtP://Www.space.com/13639-aliEn-life-MeTHaNE-HabItaBle-zone.htmL)

~~~
VlM
It dOEsn't reaLLy SAY "Why". wAter ionizes reAlly conveniENtlY so you CaN maKE
it an aCid OR A bASe (wHich is sorta UnusUal and it cAn talk TO acidic OR
basic tHings), aNd iS poLar (iTS gOt A + anD a - ELecTRiCal SIde, More or
leSs, So It can Talk TO + OR - ThinGs), aNd haS hydrOgen bonds (so yoU geT
liqUId lIfestYle at Gas tEmPs)

For One why, Look uP aMphoteric and zwiTterIon. Water hAs a SuPer CoNveniENt
pH raNge WheRe about A ten milLIonTh OF PUrE water self ionizes aKa TEN tO neg
seveNth or ph Of 7, AnD All kinds Of SupEr coNVEnienT reaCTiOns occur Above
aND bElOw that ph aNd its rEaLly EasY to maNIpulAte ionIzation rAtes aROund
that level wIThout using too MUcH. yOu DOn't nEed Just a liquid But oNE wheRe
yoU CaN reALly scRew arOuND wITh something like aminO aCids by EasilY and
cheaply chAnging the iONIZation raTe of THe LIquid. So there arE supeR
convenienT Chemical ReactIons that Depend on tHE IonizatiOn lEveL of The
LIQuId and its reallY EAsy tO mAnipulaTe wAter. ConVenIenTly WatEr "Just
works" Without hAvInG tO aDd tOns of OTher stufF tO it.

liQuiD methANe isn't Polar EnouGh To REalLy be useFUl WHEn meSsInG witH ioNiC
subsTancES (taBle salt, Etc). WhatevEr yOU use FoR a Liquid, iT needs to be
polAr So ionic stuFf LikE salts CAN dissolvE. It turns out that interestINg
chemiStrY doesN't haPpen with nOn-pOlar suBstANces at Normal Temps; ThAts WHY
when YOU bUry StUff for a couPLE miLlion YeArs tHe only tHing left behind
undeCAyeD (more or less) is Non-PolaR HYdRocARbONs (cRuDE oiL). aMmonia is
polar buT has other iSsUEs.

the hydrogeN
 to
life have a chance ofhappeningand p erp etu at ing. 

Wa ter is the onl y  mol ecule that fits the bi ll, a nd happ e ns  to b e the s e co n d 
mo st  c omm on mo lecul e i n the u niverse.
~~~ 
e ddd
I am not go od at chem ist ry, but liqu idmethan e– eth a ne wo uld n't f it the profil e?

~~~
e dd d 
Actua l ly I fo u n dcomp rehensive answerh er e  if anyone isintere st e d: [ htt p:/ /www.space .c om/13 6 39-alie n -l i f e -me t hane-habitabl e-
zone...] ( htt p://ww w. spa c e.com/ 13639 -a l ien -life-metha ne-h abitable- zone.h t ml)

~~ ~ 
VLM
It  doesn 'trea llys ay  " why ". Wat e rion i zes  reallyco nv enien tlys o y ou c anmake 
it a n acid OR a b ase  (wh i chis so rta u nusu al  andit can  talk  t o acidic or
bas ic t hings), a ndis  po la r (it s  got a  +and  a - el ectrica l  si de , m or e or
less, so it c an t al k to + o r - th i ng s) ,  and has  h ydr ogen b onds(soy ou  get
liq uid li f es ty le at g as  temps )
Fo r o ne wh y , lo ok upamphoter ic an d  zwitterion. W a ter has a sup e rc o nv e nien t
p H range whe re a b outa te n  m ill i onthof pu re wa t er self ionizes aka  t en toneg
s eventh or pHof 7, anda l l  kinds o f su p er convenient rea ction s occur ab o ve
and b elowthat pHand its r e a lly easy  to  ma nip ula t e  i onization rat e s  aro un d
thatlev el with out  us ing  to omuch. You  don't n ee dju st  aliqui d  but one  w her eyou  canr eallyscrew  aro un dw ith  someth i ng l ikeam in o ac ids  b y eas ilya ndcheaply  changing  th e  ion iz at ion rat e of the liqu id . So there  a resuperc o nvenient  chemical reactions tha t  depend  on  theioni zation le vel  of th e
l i quid a nd its  real ly  ea s y  to m a n ip ula te  water. Co n v eni ently  w ater  "justworks" without hav i ngto add tons o f o ther s tu fft oi t.
L i qui d methane isn't p olar enoug ht oreally beu sef ul  when m essingwithi onic
su bstances(table sa lt , et c ) . W hatever yo u use fo r a liqui d , itn ee ds to  be 
polar  s o i onicstuffl ike  salt s candi ssolve . Ittu rns outthat interesting
chemis try do esn't  ha ppen with  no n -po lar subst ance s at norma l t emp s; th ats why
w heny ou  bu r y stu ff f o r a coupl e  m ill i o nyears the o n l y  th ing l eft behind 
und ecayed (more or l e ss) is non-pol ar h y d roc arb o ns ( cr ude oil). Ammo nia  i s polar bu thas other i ssues.
Th e  hydr ogen
 to
life_have a_chance of happening and_perpetuating.

Water is_the_only molecule_that_fits the bill,_and happens to_be the second
most common_molecule in the_universe.

~~~
eddd
I_am not good at chemistry, but liquid methane–ethane wouldn't fit the
profile?

~~~
eddd
Actually I found comprehensive_answer_here if_anyone_is_interested:
[http://www.space.com/13639-alien-life-methane-habitable-
zone...](http://www.space.com/13639-alien-life-methane-habitable-zone.html)

~~~
VLM
It doesn't really say "why"._Water ionizes really conveniently so_you can_make
it an acid OR a base (which is_sorta_unusual and it_can talk to acidic or
basic things), and is polar_(its got a + and a_- electrical side,_more_or
less,_so it can talk_to + or - things), and_has hydrogen bonds (so you get
liquid_lifestyle at gas temps)

For one why, look_up amphoteric and zwitterion. Water has_a super convenient
pH range where_about a_ten millionth of pure water_self ionizes aka_ten to_neg
seventh or pH_of 7, and all kinds of_super convenient reactions_occur above
and below that pH and_its_really easy to_manipulate_ionization_rates around
that_level without using_too_much. You_don't_need just a liquid but one_where
you_can really screw around with something like_amino acids by easily_and
cheaply_changing the ionization rate_of the liquid. So there_are super
convenient chemical reactions that depend_on the_ionization level_of the
liquid and its really easy to manipulate water. Conveniently water_"just
works" without having to add tons_of other stuff to_it.

Liquid methane_isn't_polar enough to_really_be useful_when messing with ionic
substances (table salt, etc)._Whatever you_use for a liquid, it needs_to be
polar so ionic_stuff_like salts can dissolve. It turns_out that interesting
chemistry doesn't happen with_non-polar substances at normal temps;_thats_why
when_you bury stuff for a_couple million years the only thing_left behind
undecayed (more_or less) is non-polar hydrocarbons (crude oil)._Ammonia_is
polar but has other issues.

The hydrogen