 what we today
call Planck's constant) was motivated by understanding the "ultraviolet
catastrophe" [2] (which was a purely "theoretical" endeavour as some would
call it today). Planck's work preceeded Einstein's explanation of the
photoelectric effect by several years. Even when the photoelectric effect was
observed, it was first noticed in zinc (IIRC); it was only in the 1930s that
QM was applied to understand the functioning of semiconductors.

 _You are confusing all the things we use QM for today with all the reasons
for which it was first conceived._ Moany of those reasons of course spurred
development in QM _after it was conceived_ \-- but none of those motivations
would have conceived QM.

With regards to your comment on the development of probability:

There was always a reason/purpose something was conceived. So claiming that it
was "motivated by applications" is tautological. _The relevant question to ask
is whether the applications today are different from the original
motivations._ If they are, then frankly, it doesn't matter what the original
motivations were... the idea would have been difficult to conceive starting
with the eventual application in mind. Eg: Without an understanding of
probability, linear algebra and differential equations, there would have been
no quantum mechanics. Somebody observing the photoelectric effect could not
have developed those tools for their "application".

I notice your other comment on the thread (OP) talks in analogy with physical
training. IMHO, such an analogy is misguided for endeavours which cannot be
reasonably well specified so as to be manageable (in that it can be managed,
with the goal in mind). Basic research is often not amenable to that because
it has tons of unknown unknowns [3].

[1]:
[https://en.wikipedia.org/wiki/History_of_quantum_mechanics](https://en.wikipedia.org/wiki/History_of_quantum_mechanics)

[2]:
[https://en.wikipedia.org/wiki/Ultraviolet_catastrophe](https://en.wikipedia.org/wiki/Ultraviolet_catastrophe)

[3]:
[https://en.wikipedia.org/wiki/There_are_known_knowns](https://en.wikipedia.org/wiki/
what we today 
 call Planck's constant) was motivated by understanding the " ultraviolet 
 calamity " [ 2 ] (which was a strictly " theoretical " attempt as some would 
 call it today). Planck's workplace preceeded Einstein's explanation of the 
 photoelectric impression by several years. Even when the photoelectric impression was 
 observe, it was foremost comment in zinc (IIRC); it was only in the thirties that 
 QM was applied to understand the functioning of semiconductors. 

  _ You are jumble all the things we practice QM for today with all the reasons 
 for which it was foremost gestate. _ Moany of those reasons of course spurred 
 exploitation in QM _ after it was conceived _ \-- but none of those motivations 
 would have conceived QM. 

 With regards to your remark on the development of probability: 

 There was always a reason / purpose something was conceive. So claiming that it 
 was " motivated by applications " is tautological. _ The relevant question to ask 
 is whether the applications today are different from the original 
 motivations. _ If they are, then frankly, it doesn't matter what the original 
 motivations were... the idea would have been difficult to conceive starting 
 with the eventual lotion in judgment. Eg: Without an understanding of 
 probability, analogue algebra and differential equation, there would have been 
 no quantum automobile mechanic. Somebody observing the photoelectric effect could not 
 have developed those tools for their " application ". 

 I notice your other remark on the thread (OP) talks in analogy with physical 
 training. IMHO, such an analogy is misadvise for endeavours which cannot be 
 reasonably well specified so as to be manageable (in that it can be wield, 
 with the goal in judgment). Basic research is often not amenable to that because 
 it has tons of unknown unknown [ 3 ]. 

 [ 1 ]: 
 [ https://en.wikipedia.org/wiki/History_of_quantum_mechanics](https://en.wikipedia.org/wiki/History_of_quantum_mechanics) 

 [ 2 ]: 
 [ https://en.wikipedia.org/wiki/Ultraviolet_catastrophe](https://en.wikipedia.org/wiki/Ultraviolet_catastrophe) 

 [ 3 ]: 
 [ https://en.wikipedia.org/wiki/There_are_known_knowns](https://en.wikipedia.org/wiki/
 whwt we today
call Planck's gonstant) was motncated uy undedstandine the "ultraviolet
catastrophe" [2] (qhich was a purely "theoretizal" endeanour as sime xould
call it todeg). Planck's wori preeexded Einstein's gxplanation mf the
photoelewtfie effect by several years. Even when ehe phoyoflectric effecj was
pfserbvd, it was first noticed in zinc (IIRC); iu was only in the 1930x that
QM was applied to unfershand the functionijg of semicindusrors.

 _You are confusing all the thihgs we use QM for today with alu the reasons
fot shlwh it was fmrst cjnceived._ Moakj of thmse reaxons of course spnrree
development in QM _afver it was conceived_ \-- but nona kf those motivatiinw
woulg haee cubcekves AM.

Sith rfgacds to your comment on the development of pwibability:

Thers was wlrays a reason/purpose something was conctived. So claiming that it
was "motivated by applicajions" is twutological. _The relevant question to ask
is whethes the xppoigatiubs today are different from the original
motivatyknx._ Pf they are, then nrankly, it doesn't kahtrt what the orieinal
motibations were... the ifea woujd hace been dyffivult to conceive starting
wirh the eventlal qpplication in minb. Eg: Without an ondersyanding of
probability, lnnear zlgebra and differenfkal equations, thdre wmuld havt been
no quantum mqchanics. Womeyody obsdrvimg the photoelechric cxfect could not
havf devgloped those toops for their "application".

I noticx your other vokmett on thz thresd (OP) talks ig analogy with physiccl
traiving. IMHO, auch an analogy is misguided fos endeavours xhich cangot ve
reqsonablh well specifiec so as to be managwable (in that it cen bg janaged,
with the goql in mind). Basiv rdsewrbh ms ofean not amenatle go gnat bdcause
iu hcs tonx of unknown unknownv [3].

[1]:
[htfps://en.wikipedia.org/wokl/History_od_quantum_iechanics](httpx://en.wikipedia.org/wikl/Histmry_uf_quamtui_mechanics)

[2]:
[https://en.wikipedia.org/wjki/Ultravlolct_catastrophe](rttpw://en.wikipedia.prg/wiki/Ultraviolet_catastrophe)

[3]:
[https://en.wikmpedia.org/wiki/There_are_kniwn_knowns](https://en.wiknptdia.org/wiki/
what we today call Planck's constant) was understanding "ultraviolet catastrophe" (which was a would it today). Planck's preceeded Einstein's explanation the photoelectric effect by several years. when the photoelectric effect was observed, it was first noticed in zinc (IIRC); was only in the 1930s that QM was applied to understand the functioning semiconductors. are all things we use QM for today with all the reasons for which it was first conceived._ of those reasons of course spurred development in _after it was conceived_ but none of those motivations have QM. With to comment the development of There was always a reason/purpose something was conceived. So claiming that it was "motivated by applications" is _The relevant ask is the today different from the If they are, then frankly, it the original motivations were... the idea would have difficult to starting with the eventual application in Eg: Without an understanding of probability, linear algebra differential equations, there would have been no quantum mechanics. Somebody observing the photoelectric effect could developed those tools for "application". I notice other on thread talks in with physical training. IMHO, such an analogy is misguided for endeavours cannot be reasonably well specified so as to be manageable it be managed, with goal in mind). Basic is not amenable to that has of [1]: [2]: [3]: [https://en.wikipedia.org/wiki/There_are_known_knowns](https://en.wikipedia.org/wiki/
 what we today
call Planck's conStant) was moTivatEd bY unDeRstaNdinG the "ultravioleT
CataStrophe" [2] (which was a purely "TheorEtICal" eNDeAvour As some wOUlD
CAll It ToDay). plANcK's worK prEceeded einstein's eXplAnAtion of the
phOToElectric efFecT by several yeArs. even whEn The PHotoeLecTric eFfect wAS
obserVed, it was fIrST noticED in zinc (iirC); It waS only in the 1930s that
QM WAs APplied to undersTand thE fUNcTIOniNg oF semiconduCtOrs.

 _YoU Are confUSiNG ALl tHE things we use Qm for today wiTH alL the reAsOns
FOr whicH it waS fIRst Conceived._ MoAny oF those reaSons of COurse spURred
devElopmeNt iN QM _AfteR It WaS coNcEIveD_ \-- BuT noNE of Those motIvAtIons
wOuld HAVE ConcEivEd QM.

with rEgards to your cOmmEnt oN The DevelOpmenT of pRoBabilIty:

TheRe was AlWays a reason/purpOse sOmething wAs cOnCeiVeD. So clAIming tHat It
wAs "motivAted by aPPliCaTIONs" Is tautological. _The rElEVAnT questioN to ask
IS wHeTHer the apPlIcaTionS TOday aRe diFFeRent from The oriGInAl
MotivatIoNs._ If thEy Are, TheN franKLy, it Doesn't Matter whAt the ORiginal
motivatIOns were... the ideA WoULD hAVe beEn dIfficult to cOnceIVe stArtiNG
wIth THe eveNtual ApPLiCAtion in mind. Eg: WithouT aN underStandIng of
probabilIty, linear aLGEBra and diFferENtIAl equations, theRe wouLd have been
NO quantum MechaNics. SomeBody obserVINg the phoToeLecTriC efFECt Could not
have dEVElopEd Those toOls For theiR "apPliCatIon".

i nOtice your Other comMeNt On ThE thRead (Op) Talks in aNaLogY wIth PhysiCAl
traiNing. ImHO, sUcH aN AnaLogy is mISgUIDed fOr EnDeavOurS wHich cAnnoT Be
rEasonabLy well speCifIEd so As To Be managEable (in that it CaN be managed,
WiTh tHe goal IN Mind). BasiC research is often not amenABle to thAt bEcausE
it hAs tons of uNknOwn unkNowNS [3].

[1]:
[https://En.wikiPedia.OrG/wiKI/histoRY_Of_QuaNtUm_mechanicS](HTtpS://en.wiKiPediA.org/wikI/History_of_quantum_mEChaNics)

[2]:
[https://en.wiKipEdia.ORG/wIki/uLtRAviOlET_caTAStrophe](https://en.wIkipedia.orG/wIKi/ultravioleT_CatAsTrophe)

[3]:
[hTtps://en.wIkipeDIa.org/wiKi/There_arE_known_knoWnS](httPS://En.wIkipedia.orG/wiki/
 what we today
call Planck 's constan t) wa s m oti va tedby u nderstanding t h e "u ltraviolet
catastrophe " [2]  ( w hich wa s a p urely " t he o r eti ca l"  en de a vo ur as  so me woul d
call ittod ay ). Planck'sw or k preceede d E instein's ex pla nation  o f t h e
pho toe lectr ic eff e ct byseveral y ea r s. Eve n  when t h e  p hoto electric effect w a so bserved, it wa s firs tn ot i c edinzinc (IIRC );  it w a s onlyi nt h e  19 3 0s that
QM wa s applied t o  un dersta nd  th e  funct ionin go f s emiconducto rs.
 _You ar e conf u sing al l  the th ings w e u seQM f o rto day  w i tha ll  th e  re asons
fo rwh ich i t wa s f i rstcon ceiv ed._Moany of thos e r easo n s o f cou rse s purr ed 
deve lopmen t inQM  _after it wasconc eived_ \- - b ut  no ne  of t h ose mo tiv ati ons
wou ld have con ce i v e dQM.

With regardsto y ou r commen t on t h ede v elopment  o f p roba b i lity: 

Th e re  was alw ays ar ea so n/purpo se  somet hi ngwas  conc e ived . So c laimingthati t
was "motivat e d by applicat i on s "  i s  tau tol ogical. _Th e re l evan t qu e st ion to as k
iswh e th e r the applicationsto day ar e dif ferent from t he origina l m otivatio ns._ If they are, then  fran kly, it do e sn't mat ter w hat theoriginalm o tivation s w ere ...  th e id ea would have b eendi fficult  to  concei vesta rti ngwi th the ev entual a pp li ca ti onin mi n d. Eg: W it hou tanunder s tandin g ofprob ab il i ty,  linear al g e braan ddiff ere nt ial e quat i ons , there  would ha veb eenno  q uantummechanics. So me body obser vi ngthe ph o t oelectri c effect could not
have develop edthose  too ls for th eir  "appl ica t ion".
I not ice y ou r o t h er co m m en t o nthe thread ( OP)  talk sin a nalogywith physical
trai n ing . IMHO, suchananal o g yism is g uid ed for e ndeavours which  cannot be 
r e as onably wel l  sp ec ified s o as to  be m a nageabl e (in tha t it canbe  man a g ed, 
with thegoal inmind). Ba s ic re s ea rch i s o ften n ot  am enabl e to t h atbecau se
itha s tons  of u nk nown unk nowns [3].

[1]:
[https ://en. wikip edi a.org/wik i/H i sto ry_of_qua ntum _mechanics ](h ttp s://e n.w i kiped ia.o r g/ wik i /Hist ory_ o f_quantum _ me cha n i cs )

[2]:
[ht t p s :// en.wi kip e dia.or g/wi ki/Ultraviolet_ca t astrophe](http s:// e n .wi kip e dia. or g/wiki/Ultravi ole t_ c a tastroph e) 

[3]:
[htt ps://en. wi k ipedi a.org/ wiki/T here_ar e _ kn o wn_kno wns] (ht tps://en. wik ip e dia.org /w ik i /
 what_we today
call_Planck's constant) was motivated_by understanding_the_"ultraviolet
catastrophe" [2]_(which_was a purely_"theoretical" endeavour as_some would
call it today)._Planck's work preceeded_Einstein's_explanation of the
photoelectric effect by several years. Even when the photoelectric effect was
observed, it_was_first noticed_in_zinc_(IIRC); it was only in_the 1930s that
QM was applied_to understand_the functioning of semiconductors.

 _You are confusing all_the_things we use_QM for today with all the reasons
for which it_was first conceived._ Moany of those_reasons of course_spurred
development_in_QM _after it was_conceived_ \-- but none of those_motivations
would have conceived QM.

With regards to_your comment on the development of probability:

There_was always a reason/purpose something was_conceived. So claiming that it
was_"motivated by_applications" is tautological. _The relevant_question to ask
is_whether the_applications today are_different from the original
motivations._ If they_are, then frankly,_it doesn't matter what the original
motivations_were..._the idea would_have_been_difficult to_conceive starting
with the_eventual_application in_mind._Eg: Without an understanding of
probability, linear_algebra_and differential equations, there would have been
no_quantum mechanics. Somebody observing_the_photoelectric effect could not
have_developed those tools for their_"application".

I notice your other comment on_the thread_(OP) talks_in analogy with physical
training. IMHO, such an analogy is misguided for_endeavours which cannot be
reasonably well specified_so as to be_manageable (in_that_it can be_managed,
with_the goal_in mind). Basic research is often not_amenable to_that because
it has tons of unknown_unknowns [3].

[1]:
[https://en.wikipedia.org/wiki/History_of_quantum_mechanics](https://en.wikipedia.org/wiki/History_of_quantum_mechanics)

[2]:
[https://en.wikipedia.org/wiki/Ultraviolet_catastrophe](https://en.wikipedia.org/wiki/Ultraviolet_catastrophe)

[3]:
[https://en.wikipedia.org/wiki/There_are_known_knowns](https://en.wikipedia.org/wiki/