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8/20/2019 Galaxies Big Banged
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Galaxies and the Universe
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What Are Galaxies?
• Greek galax = milk• William Herschel, 1783: A disk with
the Sn sli!htl" #$%center
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What Are Galaxies?
• 1&th 'entr": (S)iral *e+lae
• *ear+"? -a"+e S#lar S"stems in
.#rmati#n?• 1&/0: Galaxies are Stars
• 1&/0s: Galaxies are like the -ilk" Wa"
• 2i!!est sin!le increase in #r mental)ictre # the Universe in hmanhist#r"
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Where Are We in #r
Galax"?• 4he visi+le -ilk"
Wa" s!!ests #r
!alax" is a 5atdisk
• Srr#ndin!#ther !alaxies is
a s)herical hal## Globular StarClusters
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Galaxies and Gl#+lar'lsters
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4he -ilk" Wa"s Gl#+lar'lsters
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4he -ilk" Wa" As We See6t
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Anat#m" # a Galax"
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S)iral Arms
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6n -icr#waves, We 'an See
the H+ # the Galax"
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-a))in! the*ei!h+#rh##d
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-a))in! the *ei!h+#rh##d
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-a))in!the
Galax":*#t 4here
et
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-a))in! the
Galax":*#t 4here
et
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4he#calGr#
)
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9#wnt#wn: 4he ir!# 'lster:;0 m<l<"
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4he#cal
S)er%
clster
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4he'#ma
'lster3;0
m<l<"<
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ar!e%ScaleStrctre
# theUniverse
t# ;00m<l<"<
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4ravel t# the Stars?
• inetic >ner!" = 1/ -v/
• What d#es it take t# !et a 1000%t#ns)aceshi) t# 10@ # the s)eed # li!ht? B3
"ears t# Al)ha 'entariC• -=10D k!, v = 3 x 107 msec
• > = 1/ x 10D x & x 101B = B<; x 10/0 E#les
• >Fals U<S< >ner!" r#dcti#n #r B<; "ears
• nce "# !et there, "# have t# stop.
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Ielativit"
•
S)eed # i!ht is 6nde)endent # S#rce• -ichels#n and -#rle", 1887 % S)eed #
i!ht 6nde)endent # Observer
• (ne # the -#st Unex)ected Ieslts in
the Hist#r" # Science % 6saac Asim#v• '#nclsi#n: S)eed # i!ht is the Same
for All Observers
• 6m)licati#n: S)ace and 4ime -st'han!e t# ee) S)eed # i!ht'#nstant
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Wh" the S)eed # i!ht is aS)eed imit
• >ner!" # a -#vin! +Eect inIelativit":
> = mc/ --------------------- ---------------------- ---------------------- --------------
1 % v/c/
• ne c#nseFence: as v a))r#achesc, >ner!" !#es t# innity
• Als#, as we a))r#ach c, >ner!" !#es) very fast
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.el >c#n#m" # a Starshi)•
At 0<1 c, ener!" is 0<7@ !reater than*ewt#nian #rmla
• At 0<; c, /B@ !reater
•
At 0<& c, 3 x !reater• At 0<&& c, 1/ x !reater
• At 0<&&& c, B3 x !reater
•
>ach extra & m#re than tri)les the ener!"• Gettin! #r 1000 t#n shi) t# 0<& c takes
1<1 x 10/3 E#les = U<S< ener!" se #r1100 "ears
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An#ther '#nseFence #Ielativit"% Gravitati#nal
enses
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What 9#es 4he Universe ##kike?
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What 9#es 4he Universe##k ike?
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(4he 2i! 2an!
• >dwin H++le, Iecessi#n # Galaxies,1&/&
• Ied%shit increases with distance
• '#smic -icr#wave 2ack!r#nd, 1&D;• >stimated A!e # Universe: 1/%1; +<"<
• (2i! 2an! #ri!inall" a derisive term,
c#ined +" .red H#"le
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As .ar t as We 'an See %Ten Days With the H++le
4elesc#)e
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A *ew *ame #r the (2i!2an!?
Sky and Telesope, 1&&;C• 4he 2i! 2##t
• G#ds #!%n
• .red Withair 9a" (*#+#d" evernamed an"thin! else ater me, s#wh" n#t?C
• What Ha))ens 6 6 sh 4his 2tt#n?• #re *ever G#in! 4# Get 6t All 2ack
6n 4here A!ain
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&0@ # the Universe is(-issin!
• ter Stars in Galaxies rev#lveaster than ex)ected
• What h#lds clsters # !alaxiest#!ether?
• '#nclsi#n: 4here mst +e a lot #invisi+le mass in the Universe
• *#t reall" (missin!, Est n#n%lmin#s
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Astr#n#mers Are *#t As U)setAs ne -i!ht >x)ect
• -A'Hs -assive '#m)act Hal#+EectsC: aint stars, +r#wn dwars,
)lanets• '##l n#n%lmin#s !as
• -assive *etrin#s?
•
W6-s Weakl" 6nteractin! -assivearticlesC
• -a!netic m#n#)#les
• >x#tic #+Eects: strin!s, mini%+lack h#les
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.ine 4nin! the Universe• 9ensit"
– -ch !reater and the Universe w#ldalread" have c#lla)sed in #n itsel
– -ch less and stars c#ld n#t have #rmed
• *clear .#rces – .si#n im)#ssi+le
– .si#n t## eas"
• Anthr#)ic rinci)le – '#sm#l#!" has t# +e a+le t# ex)lain wh"
we exist
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.ine 4nin! the Universe
• 6t Est came #t that wa"• 6t has t# +e that wa" #r reas#ns we
havent "et disc#vered
• -a"+e there are an inJnit" #niverses +t #nl" th#se with certain)arameters devel#) intelli!ent lie
-ltiverseC• >n!ineered #r desi!ned
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.ine 4nin! the Universe
• 9esi!ner?• 9#esnt >x)lain An"thin!
• 6 the 9esi!ner can create a Universe, wh"
is c = 300,000 kmsec instead # B00,000?• 6 9esi!ner had t# have c = 300,000
kmsec, wh"? What wh#?C dictated that,and wh"?
• Wh# sa"s 9esi!ner is an"thin! )ictred +"an" reli!i#n?
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-isinter)retin! Ielativit"
• 4here are n# a+s#ltes – S)eed # li!ht is a+s#lte
– 6t ma" n#t +e )#ssi+le t# +e a+s#ltel"
ri!ht +t it is ver" eas" t# +e a+s#ltel"wr#n!
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Where Will 6t All >nd?
• 4rilli#ns # "ears: Star #rmati#n ends
• 10%100 trilli#n "ears: Stars st#)radiatin!
• 101; K 10/0 "ears: lanetar" #r+its deca"
• 103/ K 10B1 "ears: r#t#ns deca"?
• Heat 9eath?
• 2i! 'rnch?
• 2i! 2#nce?
Wh t 9 ' l 6 l
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What 9#es '#sm#l#!" 6m)l" #rhil#s#)h"?
• *#thin!
• At east, *#t et
• 6t 6s H#)elessl" rematre 4# 4r" 4# 'reateA hil#s#)h" 2ased #n '#sm#l#!"
– We can sa" what the ate # the Universe will+e +ased #n s)eciJc assm)ti#ns
– We are a l#n! wa" r#m kn#win! theassm)ti#ns are c#m)lete #r c#rrect
• 6 "# s))#rt "#r )hil#s#)h" withscience, +e )re)ared #r science t# )r#veit wr#n!
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