BSTJ 20: 3. July 1941: Forces and Atoms: The World of The Physicist. (Darrow, Karl K.)

11.7 MB·English

Forces and Atoms: The World of the Physicist?

)NE of th signs whereby a physic may be kaon is a Sondness fr
‘pitting dots upon backed, This ent an raliral at, bal
spabolic prectice. Iti symbol of is manne of celine ar a
fo mutivce incredibly exormove of parties ined exal. The dats
Sand forthe parties, and che tre regon of the blckbesrd forte empey
Shows lieineen thom, Tbe babi as not indeed been universal. enya
‘hinker baa preiered to consider se world ae «continuum, veo ey
‘rll and we ball se chat this alternative as always been very nese it
the bechgroun, even wien che “etomia” were al thee sees eiampbat.
“Leta bowever defer thi ther Wen, and derive as mush as peesible from
‘he notion of pees in a vod
"Bat whe thous ace et dows om te nerwia lan boa wita regions
‘et back emptiness ten, the seni fa rr empl ein fae,
‘nly began, forthe major rt yl to barton: he anon of Che forse
fcaong te particles Though thee ast be epee ion: each ober by
secs spperently eoply, yet Sey are ut uatwaecous of each ole, fr
Ch of tern be ubjec oa force dhe nesltant a ny Tors de to all
cet
‘One might attach an arrow to eich dt, to sgofy the erent and the
Aiwetion of the flee which asts upon it. Oae might ezaw vandering
‘arse all ove? the bowsd, to ifimte at every peint the cicron ane
Fteeagth ofthe Snr which particle nol feel, woe ea thal pi.
‘This isacerpted patie, BL wal ewer ein ly war atu
‘ions anlar amos wece sachets enesge than forthe geese ey
ae Perhaps at last Ue MacKnuard sid be seared with a uno,
eating of elt spay Cas x pati in jae on KIL ently La
ee, bat feet the InGuaace of the other. “Among ous notae-distent
sversor here seis to Lave ben ¢psyehslogial need fore gesture ofthe
Sert they talked about space as though it wote Hl witha *modiam or
“peer”, bec it scored rng to Them Ivey Thee fe empty 4
the particle whieh worl ini are sje te Toms, Ont generation Is
rely lost the need, wheter of an aeiter Ua oceny clas spsce et of @

ein ene at» zr ne is Tha Sat
ano arous sa

senza of sal to symbolize om the Blaekboend. Let us ty that wpace
Incmpty and lave the backénard bla hetoen the dots, without dering
lurselves deprived ofthe ght o saying shut the peticles eet ead aller
forces 08a fas one ast

‘Wht ie thne toe aid about the frees? A very grat dell fr most of
theoretical plysis a mae upof belief ides aon the Fores, uaz
iy the miematia! operations very bard and very longewinde, i far
oo may extes—requied fr risking he cea relly wee Sa peak
logiamine irdicaed ly chal wenenen tt Kam ting ocd a ing
at 1 nt be Fuld ie vert ertree, nr a the noe of the
fons, “Orly the most gern ef statements ean be mad in what follows,
(OF theve Thy dare ot once the est, mica i negutive un eerie

‘Th force connate puclyrepuine, Fou i they were allo Pe prices
‘would nibh off ino the uttermort depts of space, sad we should have no
‘ode! at all fo auiverse whic, with ll a faults des manage at least to
stick togetet

Theofro there must be attractive frees, and thee by and large must
coverpomer the zepulsive ones if eny such Use

Bat need thee be any repulsive forces at al? (Let the sopistcal’
reader Low lengli 4 ite that (oe nr lect ores which te real
iv o that he my ena wth an open rind as to whether atch col
be veided) A: rt tay nol scem sn; an one may vox the guest
{autassity cf Nerton, wa softer thot tle ronal hime mth
signing to al hadi the pewer of aliraring ne soother with the force
Gf gravity. He dd aot s content kinel, and we shal lear thie shorty.
For the erent let lt becemeeved at For of altracion unopposed
would ted toe all ofthe partes of the universe int asin erick
Crap. If ae volume of rar pacientes ema pale would be
that of the ulknate cum i he volume of mach petite were breducble
low cotta tinimuntUut we ala ere Ton nd bat ha en can
fvoive of ial Dridy, ete mist be acaeihing to uppese the arate
fovees. To coll sh's something by Uae nome of "Tore or even to el t
1 ay saglo naz, vould be lo ini is endely, Soto toe second general
ssstement T ve Cie fn:

Thre sate arate fre, tere wa ele be ontgone tthe.

eomcene wasted patil pesblss fe teary of pyscsideoited
1 sim a the profouscest, te pyoblem of these antagoats might wll be
selves ch

‘Thais indeed oe famed ana spectaralarcae hich maker one stage
ist clear Tei the case of the evenly badies the planets reveling
round the su, he atelites acound the plinets, Way dees nt the moon
‘allonto tae earth andthe arth falinto shorn? Newtons laws of motion
Pa cca sySraM TeCmVrcat JOURYAL

tell the anzmer, The snlanist ie mation—or, to speak more prvéely,
Fotweatuas ot to speak yet mone precy, nglar momancu. If tt
ticlessturat one ats ate moving with relative motion which s
ot ona the lize that joins the aey aver wil meet. Hewover great
{he allel between them, it etanot driv them lopeer. Attn
fen leno tance than exosiais them to swing in permanent ocbite around
‘hee uannon cette of mace. Thee

“Phe esl Bier esl to ng syn Wap sale By the eaccine of
easy ith mation for the adage rt.

However sur his statemer may now seem, i Uy we macs at
jen inborn in Ube uma mind, "here a8 ar ef wher fe ie
that movin des et ef ital, ones rong sustained by ¢reversossng
finals, Were wotion to’ de out of Sts, 1 cou mat he an eternal
Ebtogonstto gravity, Newton eura the way fr the new Mes iy abe
ing the ol one

“May we now assume that theultimate parties i the world act on exch
ther by gravity elone, nth tution as the wle antagonist to keep the
‘hivese fom gathering into a sage comp?

"Thc ancer to this question i orhnght and iereocable NO.

‘That the ensweesoule be nis not all supesing ce this gerealion,
‘yhich sine ote ones then peat, the ectmngretic oes
viaje “hove who undezrate the prowess of eur forerunners sy fol
Srpise on owing tla Cie negative anwner eas quite ce apicest se
Newloa,. Ko aokyy is ever ueeeed for eaotng vorbcim what Newton
serve in English shough itis x dingrouact forte quote, whos ating
{ort oir ly contra mith thes clogunce ofthe seer nei setey.
Taevring the danger, ite for he Opt (a ako whieh the mame fs
‘decidedly short ofthe sep)

“se attractions of grovtly, mgnctism and eeirivty reach wo very
sensible distances, and so have Teen csorved hy vulgar eyes aul there
Spay be others wtih reac ts smal istanees te Mezco cca observa
ion. Tho pars ofall besogenes! an odes whic flly tins ont
another sick gether very strongly. Ané for expisining lw this my he,
ore tase iavented hve! aan eich s being the questions vl ere
tellus that coe ate usd togothor hy re, teat by an uct quality,
for sather by nothing; aml cll, bet hry sick cegeter by comeing
Imotions, that i, Uy aeatice ret areny hauslves [fo ater infer
from die cohesion, tt (heir evel actact one anuter by some fore,
ic in immetiste cml fe eaceeding)y strong, t smal stances per
PORCES AND aTous oe

forms chemical operation
sensible ect.”

‘Further slngin the Opts we sends

‘Ths Nature wl be very coolormable to Lerall ar very simple, ese
forming all the great motions of the heswenly Lace by Whe sttacion of
‘avty which interes Umeha, el slmost al he ene aes of le
particles by some othe attractive al reeling powers mich intteee the
tril

With the powerful aid of Newton we have now distinguished between the
attractive free af gravity and another alate fore, for whieh Lsetain
the old-fashioned name "cbesion”. T gin another basis of tution,
fe sich could aot Have heen fod unin the mid-ineeesth century
{he ceuivalen of eat with meckonicl ark wus tablished. Cansier a
lece a eld aqui matter, ar put tne qirtion: bow aul work, an
bee done totais atm apart asset the into the nite veaches
of sacs i tae oly force where thay selon ane another iste teacrion
Df geviy? "Ths questin i angworale i ie keown now masve the
toms nre ad how far epezt (othe eveiage) ly ares Thee things are
aos, The vault of th eration it be cmpazed wk the amount
of work which seetualy experi —in te frm of ent wea the eli or
Tid is vot ed inns waver. I blow thu only abou te Bloat
part of a milont part of the eat spent devoted to "breakog dow
the giaviaciona bra, ts cong wrk ines the steeion of grave
wale is overcame sen the storm ace liu, AL the rst segue
for overcoming th rae tina‘ forse! cakesion,

(Gaviey now is pushed ito the baryeoarl ul srk into the retire
Insignteacce which ay be gauge ram Fe act that nthe endless spel
tione of physicists ard cheats 28 to how matter ie bit up and joined
tegether, i's completely lft aut. The lense hi ominates the plants,
‘ich nates all so ado ld ad ight Ganges fal froma
ho nmaning tia t shouldbe trv compared wih thers which the tame
‘et The geese vanguishes a8 the water bole Out ofthe Lee! “Lviv of
‘couse by compariana unl, and at anal tance, aoe at gest a to piace
{he situstion Beta, tthe forse ol valaeion whch jy Arvid a great
tances, glauote at ama. Thief Che contrast which ie ipled by the
lecinial Ua uf psc, ong range fore” wea ebort-ange oss

reaches aot fr from the parties wth any

1 he camoniatn for mee wae ade by a eleague Dy. . Mui othe
oo vaio ray aun re ti
eee wiley te mk wage tr apeadng ie rey pant
BST MapSlatac ESA n the et re ae ee nee
SES See Rae te rs nh
oT [RELL SYSTRM TECHNICA. JOURKAL

Cavity fs lonerange, because fs avay getly with increase of distance;
fobesion is het range, been it ls precipitate. We sal aon
‘De meting wth ules xateples of cher acter.

‘One othe ac to luseat the short-range quality of the eshesve forces
When a kettle of weter x boing away on the store, Uwe amount of heat
ons in dzpersing the nt rie inch that eocets i he se as is
ent in lspensng the scaod, and the thi, al each of the others down
tod including the ast. cou not Be oo, che parties were dren
together ny nortan log-rnge ares for then exch cube inch would be
asker to dive lf than that mich st preceded tin che vaporous state,
ince thee would be ee of he is easining behind Uo attract

"The celestial bes—seefale2 they have bees in showing us the Ls of
notion have therefore served ua bly iy ining that gravity is dhe sole
Sttractive fice, 2 Mat whieh is quite leading. In eaotber important
respec they fl piv us loads they show us ne examples of callin.
Collison, more commonly kaown us mya, sexe of the mst important of
farthly phenomena, as ite ane of sie mast urcomfortable, The spple
thie the onal of Newton, ipized him wit the aw of ravtt-
Tin, tay bse boon legendery yes i it wae rex) we may be sure cht it
fended teal fa clisin-endod nll, uo ts ecence, Ti wot pss
through fe glo and pop ave ofthe guotnd in tre Antipdes; i did not
instal tere withthe rs ue Ge oof the uchar; It bounced an
rolled Bitsy pethays, nl en lay quell pening against the earth,
fotieand whole, Le ears was iupenetabie to the appl, athe apple
ode ear.

‘We do nat even hove thnk to pact, to be tah tis lesson about
Le ipetable, Not lees impressive than the act cat the pies off
cls togetbey, io the fat Ut it does rot sak. For any peeticlir
‘hie of tempecatare wl pssue, his parbiular volume wich ets
towne, Work or beat must bo expended fo dito itor tear it apart alto
ster bat els work st beexpen io ake ie dense,

Having aeribes to ettrsctive fee the fact tha i takes aeat—or let
tne say nenceformar, energy eo voporive« pce of matter odo iui,
we now soci lo elie fret the fact that it takes energy to squeeze
he pie, The forces met be short-range sil more short-range thin are
the cobesive foros msc 48 these cme into Hay to capture the ams
and hold the tagesher,bafve toe get thet oppertoity of crying “Bold,
enough” They mist be very pote, forthe most eric pressures which
Inve heen achieved by man da mat eval to agueeze the most eumprestle
oli ino hull uf is ovgnnt volume, Why tale of ariel pressres?
treryere inthe globe nf di rt, except widhin a hundzed miles ofthe
surface, te presur ia greater by fa than ny of them; and yet, the average
dhencity of tho earch ew Us double ato es seperti crt.

‘We have imagined that as to atoms spproach each elle, the gravee
ional ence Sete them rss genty, te eobesive face cetinng wedee
ectable til they corse very lowe together hen a soa sill Uistace fe
‘gins a sharp ar! sen ree wie ech cnn ite vale far over that
‘of gravity. Now we are to conceive of yet thitd fore, repulsive, wado-
tectale til hey come rl closes togetbir, tea st leer critical distance
centering ona sharper more suddea Fie which raply caer its value fat
‘ver thor of both ofthe oter te.

“This erentil an powerful free sno name itsowa, ‘Thi becouse
‘ei sualy described sn worn not oowoying dicty the neta af lone
‘What we have now enounterl isthe eonoeat of tae iacempreseie lm,
‘the patse of ireducbievolme—the dacs're thatthe atome are to be
pictured not as indniely smal like the pointy oi goometey, but e¢ bard
Finpoucuabie lati plets, minste indeed Sut not iaconcivably s. This
{na docite frankly expend by ray thinker of the as, who pepe
‘vas tne unin than we co eeciveuncrccll thas diel dogrm of
the point of infinite smallness, cesken agat ip Neston: "Te eooms
probable to me that Gol in the hoping fermed tater i sly hard,
sissy, inpereauble, moveable parca. incamperably bardet tha
‘by porous beds compounded of then evn en very hel ee raver to eat
tor break i lees; no onary powering able tncvido wane God Mimgelt
‘ade one i th tet tetion,

"The complecaly unsquezzable atom corresponds to a force of repulsion
which poses suddenly from ero tow nti otongth st certain eis]
Aitanca The eel distance isthe radi ofthe etna.” “Revere the
‘een of force af repulsion eng rapilyindood, but alvays cntinuoly,
sto pticls crew noszer—thseoreepunls na qoeembl stot, wit
uta definite radius. Soi end que fn balk se comme, and tis
Sens to rule aut the orm ies, which anyhow is move dete than one
Ties to accept. Tels nos ru} entirely ont fr there may be lntestces
‘among the pote, and Ue srinkage entails by preseue may basta
to theatomssoseitng themselves tha hocwvtcs kesenin ssa. Hovever,
this doesnot soem aleyte, si te beter to acept a compre stom
and male it hace with she cavities the esponeibiliy for the sbrinkage
‘Theo there if alco the fct Tha sls end hen, warmed, The
scribed tothe atoms dancing arcu wi the hey and so we appseech a
‘ew station which epson ant ativan ali es he te antagorite

Thstead of exploring this situation further, ct us ask wether there ie
<ierene beeen te concept ofthe eroorlss sua tam ad that
Me BELA SYST100 TECHNICAL JOURNAL

the forced eiowslydevicé mhichThave Deen dosing? Vormsly,
‘here inact, But io pees of re mach which tho rind next tes to los,
‘here ia diference, and ret one

‘The compresible atom being vere pla, one acks of what iit made?
an finde tht one thsng nf x pntiuons substeace, esti an nse
‘One wl is irying tn became thuragotag amit fs hey pase bn
Uleavera continuum atthe bas ofthe wry. The eispleaure ould not
‘ve long lasting if by asegng nf sip qualities tothe contizem oe
foul ecrive ne yt nueris! value for Ling thet cen be measaresl—
ifone oul afer, frinatance, hn I enntinuum by ts natore divide self
Into slebule of just she se aia the srt of cya demands for
the atoms, Were la ince ia ale phyies wi a alcltionsingusely
Tike tis but ingore, Le feat bee not heex dene. Tes not an slequate
felott to soy thatthe thooughging mtomist & obliged to ass to his
toms tbe ses vd the masses Which they actually have, without giving
nny deeper seoom, He arages to avoid the question; it becomes
devious when the eotsauams i browght xpos the scene. ‘The coat
access ay ie by way ofthe cotirsary, hut it a zoed shat snot been
sactesnfely tae,

“Phe forcefaldexocod the peptide being zccepled, ine ask why
lois so curious fore fed? An Trececaquere edd woul seem vo astral
te ol evan to ak for futher explanacon (ut shi obablybeczase the
Toma end bos rl yeaa a al cetanee forget ncastnced to
"Ths xnaton of shortage stuction wth x repelsion sl shorter ia
range ies out fom expliation. Could one but srtebow rade all to
Invereesquace forisy ime cud be more content. Tals yd seems
inpasable, bat ale Tae hoes trodden ult wed Loddox- tosplere
fucceses, ‘Therefore I lay aside the eompresible scm scooped oat of
fontinvt, malniag that even now wehave ot heard thelastofic. ‘Two
ages of preparation ave now reeuze.

Tit I ust te mre earenencelorvanl in asng the words “tor” al
“parila. -itherto [have ured them inlerchangaély; rom tis momen
ony “sam isto have ene meaning ard "paride" acter. Of the two,
fl be “stem wich comes the closer to meaning what both words have
feeant upto new.” Atm wl altravt alam By the force of eoheson; stom.
nll ep atom by the nameless shor-raage force. ‘The lnms in their umn
Il be made up ul move cemeatary pestis, bering sel names a5 “0
Se! wl “cin. Aa te ees between ther, tha is the topic to
thick we are coming

‘Sted, T nus irae a lng last the frees which he es der has so
Jong been ising fom this dieranes the dectromagsetic.

(Of thee, ii the letostatic” fore which stationary charg exert on
ronces ano arous a

one another which concensus he minal, Neston spoke of iin one ofthe
[petages which Thave just bsen cis, but the plas was dovies hie of
Knowing how i rsembea gravity. Both follow the law of the inverse-
‘sre ye two centuries were to rayne etweea the years waen Newton
rove thi for Ue one and Cosa oe eater. The elctcetatie Cnet
Sela enh thn grail, fori inc attraction sad «replon
These are tio caters of Cargo, the positive ai the negative: ay
‘urge repel shee of ie os ceteginy, atcts owe ofthe ther

"This entry ypon the ene cf a engtaage repulsion modiics the prspects
cof successful petro ofthe world sea cngetcs of pestle, wl seems xt
fret gece to brighten them greets, Dime gravityforget at
caheslon pat che question: in an inaginary universe male up of eestrtind
Yui: some paitive and same negative, acting on ne another by eto
‘ate fases only, i Ic pase t have Sablity nih lof the parses
analig tl

“Reais the ausver is 3c. ‘This is 20, homer, to dipping: were
semiomed Uo mations iheartegonst af yvityin te esestil see shall
‘ee nol ne intel a bea lly tte lectrotatie reps, the 2
them eanjintly Deing the antagonists of the attraction!

Nowe re] agra dsapgoinrment, oe sands coneonted aga
by the rthles negtiveamsver, Tae pat revives: Ikave sis that a foe
‘Newtonian pilose mould scarcely have accepted motion athe det
les antagonist ro gevity, becaise he woulz haveblive has motion dee
tuted tae, Wel the tion ofan elected particle der into ef

‘ivy the elerirumacie tery A provian mst bee befserted for

rorreties sake, Hag doesnot alter the sitvation.Uaifrma motion
‘hue wot tnd Ee eat- Dut ufos sti uate to oot ambitions.
‘The exc: motior of ¢plabet, ce eving af a pencultn vw lest the
hoo: mas: he sul but these ae accloratad tons an accra
seelions desvoy Uetaeles, when the moving body ie elcid. hele
ence pases int ligt, end the bady sinks to vest. Aristotle was avenged
inthe nirenth cotary on those wha ancered st Btn for What be hed
ledivet of motion geet, was nec wliat they belive te moton
leletricty. SU, ae nearly eveyone ene thee afer ll am elects
‘al theory of mats she lemertacy prtvee ae deta ty we elie:
fad the forces between tam re deere oe Wcrmagnetie

‘low ie ll histo be reconciled?» Dy a statemer whic 's ie prado
nena one—proside, st that all works ut es well as picts now
Ihpe, aa provide als Ga we avert one eyes fom the phenomena called
“elon, Having inagined the eeucutary particles ponds poses
of mass and Laaring lui, end acting ope noe anther By eleeomnag-
netic forts, we are to treat thelt mations by the meth of quancu
mechanics nd rot by the mete of elasie meant,

wil aot pretend hl this ea ight innavaion nor ty to repre it
nyching lees than a geet abd tole revlution in some of our most
Cherished habe of thought. Coneptsfonsery seep, even thse of pos
tion and rdon eerselves econ hey; there are ills nd abst
the meatal technique Se novel and hacd. Ye inthe pictte of the
‘niverse ax now presnte there re parties poses of change ané mins
there ate eeetcragnetc forces beeen the pies; uate is motion of
the parties; Ure i adetion, whic iti jst t2vly perisibe to die
regard fn an outline like thie one, and which Tam dress and onside
‘ofthe realm of “nocear”phenciaena there nothing ese. The stay
Uf the ware, that aay, ofthe pictore, ls asured by attractions and
fepaleionseletieal ia mataze, end hy motion, with radon laying an
‘ssentn a

“The hydsogen atom appear: tere the eye ofthe mic as asystem of a
nudes ada electron: to pares of known que] al epposie charges,
Of known wegull tase, attracting ono anorker by electrostatic fore
‘The force drum them togeer, but there is kinetic energy and there
‘motion, and 20 they sty apart. Tt ies a éefnite amount of enexgy to
pate thd, ane the thoy derives ite actual vale very exactly frm
Ibs principle, Any bes atom appears before the nnd as sate of =
tudeas and "yo or tore elects, "The rca leas «positive ehsrge,
the electrons are aegative the nvlen attracts the eectrens, but they wee
foe atte; ier szstion; betmern the atlzectin ad the motion Use
epulsin, chee Is atabiity. A molrele ia system of to or more mie
postal changed aud tro or ree elestone egetively charge, and the
Same tier qualities Eold the babe. A tangise piece of meal is an
mori svliude of nucle cal wecians, these ater enjosing a very
Irde arity of motions sere waving almost a rey ws though tbe retal
Sreven cau again the lane shed, themetal tering nee eb
ner Wo explode

"Al tei « progromne fr te explanation of Nature; ad it ia your
gramme hich has been largely fulfled—vhereore thie lecture and
pettion ofthe ome. Not everything hasbeen expleined, ror ever willbe
uite apart from the pkenereon call nuclear, ene ace counts Tings
nd kappenings on eur which oreo eomplicsal tat they roy well obey
four fundamental ls withoat ever giving ue the chance to prove it It
‘re sbould apply our amueptions to hom and stat to workout the conse
“Goences t wok lake a geolgieal era to fn te job. Peskape all phe
omens of He are of thi type, .The most tat can be asked for thal che
‘heory should deal expably wth wll the pheaomena for which fe mat
FORCES 4M ATOMS 0

reaonahly be chimed tht they aso completa ody any teary. 1
Ab stale tate thy waee pies eetogoai ce
fd qsten canis doe ean It an bere oe eet
Stah'se much Got tla arses cepa pyc today ie
wens to ich kaye ci

Te the ito cheny et us conr the stanton of the sere
tne

Grey remns qt an nae of he lit oes, aie
probly a guy of sce as Hnsln ho pope

“The charac free semai tie, wo ephned in teas of
snycing suse ang acme byte Uy etre
Ur te acoant page teu foun to een ate a Tit
which renee the amr etree the woud, ‘The maton of ery
The genention an the sboton ef libs sow a te Tres a8 ork
svi the sun eling tee tt eed pares a ich he
Tin asc nce, ned by" noha aod by ie onal mater

Cohn, and he hemi fore which bind atoms nto melas 0
rie etsy into, nes ease oe nh sh
{feline to thr nd ed tary tthe concep oft meee eso
ntl som: hte re eis on te strane trem
Sekar rca iestoapareenteue Tejada
Jot como oc th a of uot mec oat
Hemant ice to extant noel ete St
8 sep ce dtitions Hl ae the lof ees ware ok te
won acies Ta thy of Canal ine ns gu
“herinty"s el advencey the tery of men eco wel! Much
Carer snd ima tne fen an we He, do we lnpag o the co
Benomens yin allio rasoaiy eda tat hey ass
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