Astr

on

om

y C

ha

pte

r 2

3A

str

on

om

y C

ha

pte

r 2

3

Most

sta

rs e

nd a

s w

hite d

warf

s o

r M

ost

sta

rs e

nd a

s w

hite d

warf

s o

r

neutr

on s

tars

.neutr

on s

tars

.

A m

assiv

e s

tar

how

ever

can c

olla

pse thru

A

massiv

e s

tar

how

ever

can c

olla

pse thru

neutr

on d

egenera

cy.

neutr

on d

egenera

cy.

If the m

ass o

f th

e c

ore

is g

reate

r th

an 3

If the m

ass o

f th

e c

ore

is g

reate

r th

an 3

sola

r m

asses w

ill c

olla

pse into

a b

lack

sola

r m

asses w

ill c

olla

pse into

a b

lack

hole

.hole

.

Gra

vity is o

ur

perc

eption o

f space

Gra

vity is o

ur

perc

eption o

f space

and t

ime.

and t

ime.

Ein

ste

in s

aid

gra

vity a

lters

space

Ein

ste

in s

aid

gra

vity a

lters

space

and t

ime

and t

ime

He p

ut th

is togeth

er

calli

ng it

He p

ut th

is togeth

er

calli

ng it

spacetim

espacetim

e..

He thought havin

g m

ass o

r gra

vity c

urv

es

He thought havin

g m

ass o

r gra

vity c

urv

es

the fabric o

f th

e fabric o

f spacetim

espacetim

e. .

Matter

tells

M

atter

tells

spacetim

espacetim

ehow

to c

urv

e a

nd

how

to c

urv

e a

nd

the c

urv

atu

re o

f th

e c

urv

atu

re o

f spacetim

espacetim

ete

lls o

ther

tells

oth

er

matter

how

to m

ove.

matter

how

to m

ove.

Spacetim

eS

pacetim

eputs

the u

niv

ers

e in

4

puts

the u

niv

ers

e in

4

dim

en

sio

ns.

dim

en

sio

ns.

It is s

ort

of lik

e the u

niv

ers

e is a

sheet of

rubber.

Anyth

ing e

ve

n lig

ht

thin

ks it

is

Anyth

ing e

ve

n lig

ht

thin

ks it

is

movin

g in a

str

aig

ht

line w

he

n it

is

movin

g in a

str

aig

ht

line w

he

n it

is

not.

not.

Ein

ste

in c

han

ged o

ur

perc

eption o

f E

inste

in c

han

ged o

ur

perc

eption o

f

gra

vity.

gra

vity.

He c

hanged it fr

om

a forc

e to a

change in

He c

hanged it fr

om

a forc

e to a

change in

the g

eom

etr

y o

f th

e g

eom

etr

y o

f spacetim

espacetim

e..

Gra

vity is just out perc

eption o

f G

ravity is just out perc

eption o

f spacetim

espacetim

e..

Ein

ste

in a

lso p

redic

ted lig

ht

goin

g

Ein

ste

in a

lso p

redic

ted lig

ht

goin

g

nea

r th

e s

un

would

follo

w a

curv

ed

nea

r th

e s

un

would

follo

w a

curv

ed

path

.path

.

Duri

ng

a t

ota

l eclip

se n

ea

r sta

rs

Duri

ng

a t

ota

l eclip

se n

ea

r sta

rs

app

ea

red s

lightly o

ut

of

pla

ce.

app

ea

red s

lightly o

ut

of

pla

ce.

Anoth

er

the

ory

is that

the

str

ong

er

Anoth

er

the

ory

is that

the

str

ong

er

the g

ravity the s

low

er

the p

ace

of

the g

ravity the s

low

er

the p

ace

of

tim

e.

tim

e.

Ein

ste

in thought a p

lanet w

ith d

iffe

rent

Ein

ste

in thought a p

lanet w

ith d

iffe

rent

gra

vitie

s w

ould

have d

iffe

rent paces o

f gra

vitie

s w

ould

have d

iffe

rent paces o

f tim

e.

tim

e.

This

was late

r te

ste

d a

gain

on

This

was late

r te

ste

d a

gain

on g

em

ini

gem

ini

space flig

hts

with the s

am

e r

esult.

space flig

hts

with the s

am

e r

esult.

The m

ore

gra

vity y

ou h

ave w

avele

ngth

s

The m

ore

gra

vity y

ou h

ave w

avele

ngth

s

becom

e less fre

quent. W

avele

ngth

s g

row

becom

e less fre

quent. W

avele

ngth

s g

row

lo

nger.

longer.

This

is a

noth

er

way

This

is a

noth

er

way R

edshift

Redshift

occurs

.occurs

.

Gen

era

l R

ela

tivity is o

ur

best

Gen

era

l R

ela

tivity is o

ur

best

descri

ption o

f gra

vity.

descri

ption o

f gra

vity.

Escape V

elo

citie

sE

scape V

elo

citie

s

Eart

h 11km

/sE

art

h 11km

/s

Sun 618km

/sS

un 618km

/s

This

is d

ependant not ju

st on m

ass b

ut th

e

This

is d

ependant not ju

st on m

ass b

ut th

e

dis

tance to the c

ente

r of m

ass.

dis

tance to the c

ente

r of m

ass.

If t

he s

un s

hru

nk t

he p

ull

of

gra

vity

If t

he s

un s

hru

nk t

he p

ull

of

gra

vity

would

get

str

ong

er.

would

get

str

ong

er.

if o

ur

sun s

hru

nk to the s

ize o

f a n

eutr

on

if o

ur

sun s

hru

nk to the s

ize o

f a n

eutr

on

sta

r th

e e

scape v

elo

city w

ould

be h

alf the

sta

r th

e e

scape v

elo

city w

ould

be h

alf the

speed o

f lig

ht.

speed o

f lig

ht.

If y

ou h

ave s

o m

uch g

ravity t

hat th

e

If y

ou h

ave s

o m

uch g

ravity t

hat th

e

escap

e v

elo

city is g

reate

r th

an t

he

escap

e v

elo

city is g

reate

r th

an t

he

speed o

f lig

ht

then n

oth

ing c

an

speed o

f lig

ht

then n

oth

ing c

an

escap

e n

ot

even lig

ht.

escap

e n

ot

even lig

ht.

What you h

ave is a

Bla

ck h

ole

.W

hat you h

ave is a

Bla

ck h

ole

.

The n

am

e w

as s

tart

ed b

y J

ohn

The n

am

e w

as s

tart

ed b

y J

ohn

Whe

ele

r in

1969

Whe

ele

r in

1969

John M

itchell

1783

John M

itchell

1783

Pie

rre S

imon the M

arq

uis

de

Pie

rre S

imon the M

arq

uis

de L

apla

ce

Lapla

ce

had

had

sim

ilar

ideas w

ith N

ew

ton

sim

ilar

ideas w

ith N

ew

ton

’’ s g

ravity

s g

ravity

theories. H

e c

alle

d it D

ark

bodie

s.

theories. H

e c

alle

d it D

ark

bodie

s.

Genera

l re

lativity s

ays thin

gs m

ovin

g in

Genera

l re

lativity s

ays thin

gs m

ovin

g in

str

aig

ht lin

es w

ould

now

be tra

pped in a

str

aig

ht lin

es w

ould

now

be tra

pped in a

pocket of

pocket of

spacetim

espacetim

e..

Whe

n a

sta

r shrinks t

o t

he p

oin

t W

he

n a

sta

r shrinks t

o t

he p

oin

t

whe

re t

he e

scape v

elo

city e

quals

w

he

re t

he e

scape v

elo

city e

quals

the s

peed o

f lig

ht

the s

urf

ace h

as

the s

peed o

f lig

ht

the s

urf

ace h

as

reach

ed E

vent

Hori

zon.

reach

ed E

vent

Hori

zon.

Every

thin

g in

sid

e t

he e

ven

t horizon

Every

thin

g in

sid

e t

he e

ven

t horizon

cannot

escape.

cannot

escape.

The r

adiu

s o

f th

e e

vent

ho

rizon is

The r

adiu

s o

f th

e e

vent

ho

rizon is

calle

d t

he

calle

d t

he S

chw

arz

child

Schw

arz

child

radiu

s.

radiu

s.

Nam

ed a

fter

Germ

an K

arl

Nam

ed a

fter

Germ

an K

arl S

chw

arz

child

Schw

arz

child

..

The e

vent

ho

rizon is t

he b

oun

da

ry

The e

vent

ho

rizon is t

he b

oun

da

ry

of

a b

lack h

ole

.of

a b

lack h

ole

.

For

the

For

the e

art

heart

hto

becom

e a

bla

ck h

ole

it

to b

ecom

e a

bla

ck h

ole

it

would

have to s

hrink to a

radiu

s o

f 1 c

m.

would

have to s

hrink to a

radiu

s o

f 1 c

m.

Bla

ck h

ole

s o

nly

suck s

tuff in if it g

ets

to

Bla

ck h

ole

s o

nly

suck s

tuff in if it g

ets

to

clo

se.

clo

se.

Insid

e a

bla

ck h

ole

is a

ll th

eory

.In

sid

e a

bla

ck h

ole

is a

ll th

eory

.

Mate

rial get

Mate

rial get

squozen

squozen

colla

psin

g inw

ard

to

colla

psin

g inw

ard

to

infinity to a

poin

t of zero

volu

me a

nd

infinity to a

poin

t of zero

volu

me a

nd

infinite d

ensity.

infinite d

ensity.

This

is the s

ingula

rity

.T

his

is the s

ingula

rity

.

These d

iffe

rent perc

eptions o

f w

hat w

e

These d

iffe

rent perc

eptions o

f w

hat w

e

see is w

hy E

inste

in's

theory

of re

lativity is

see is w

hy E

inste

in's

theory

of re

lativity is

rela

tive to y

our

positio

n.

rela

tive to y

our

positio

n.

Goin

g in y

ou w

ould

be p

ulle

d a

t diffe

rent

Goin

g in y

ou w

ould

be p

ulle

d a

t diffe

rent

am

ounts

.

am

ounts

. S

pagetification

Spagetification

We c

annot

see a

Bla

ck h

ole

unle

ss

We c

annot

see a

Bla

ck h

ole

unle

ss

it is p

art

of

a B

inary

syste

m.

it is p

art

of

a B

inary

syste

m.

If the m

ass is m

ore

than 3

sola

r m

asses

If the m

ass is m

ore

than 3

sola

r m

asses

you c

an h

ave a

bla

ck h

ole

.you c

an h

ave a

bla

ck h

ole

.

Mate

rial tr

avels

aro

und o

uts

ide the e

vent

Mate

rial tr

avels

aro

und o

uts

ide the e

vent

horizon b

efo

re g

oin

g in its

part

icle

s r

ub

horizon b

efo

re g

oin

g in its

part

icle

s r

ub

again

st each o

ther

and h

eat up to 1

00

again

st each o

ther

and h

eat up to 1

00

mill

ion d

egre

es.

mill

ion d

egre

es.

At

this

hig

h a

tem

p

At

this

hig

h a

tem

p x

rays

xra

ys

are

giv

en

are

giv

en

off

. W

e s

ee t

his

fro

m e

art

h a

s a

off

. W

e s

ee t

his

fro

m e

art

h a

s a

ring o

f ring o

f xra

ys

xra

ys

calle

d a

n A

ccre

tion

calle

d a

n A

ccre

tion

dis

k.

dis

k.

The f

irst

bla

ck h

ole

bin

ary

syste

m

The f

irst

bla

ck h

ole

bin

ary

syste

m

was C

ygnus X

was C

ygnus X

-- 11

This

syste

m is a

n O

sta

r.T

his

syste

m is a

n O

sta

r.

It g

ives o

ff flic

kering

It g

ives o

ff flic

kering x

rays

xra

ys

and the u

nseen

and the u

nseen

com

panio

n h

as the m

ass o

f 6 s

uns.

com

panio

n h

as the m

ass o

f 6 s

uns.

Bla

ck h

ole

s o

n t

he e

dg

es o

f th

e

Bla

ck h

ole

s o

n t

he e

dg

es o

f th

e

Milk

y w

ay d

o n

ot

gro

w m

uch.

Milk

y w

ay d

o n

ot

gro

w m

uch.

But in

the c

ente

r of our

Gala

xy they c

an

But in

the c

ente

r of our

Gala

xy they c

an

feed a

nd incre

ase in s

ize.

feed a

nd incre

ase in s

ize.

Recent evid

ence s

how

s that m

assiv

e

Recent evid

ence s

how

s that m

assiv

e

bla

ck h

ole

s a

re in the c

ente

r of gala

xie

s

bla

ck h

ole

s a

re in the c

ente

r of gala

xie

s

with m

asses o

f a b

illio

n s

ola

r m

asses.

with m

asses o

f a b

illio

n s

ola

r m

asses.

Whe

never

there

is a

chan

ge in

Whe

never

there

is a

chan

ge in

matt

er

like b

lack h

ole

it

cre

ate

s a

m

att

er

like b

lack h

ole

it

cre

ate

s a

dis

turb

ance in s

pace t

ime.

dis

turb

ance in s

pace t

ime.

This

dis

turb

ance is c

alle

d a

Gra

vity w

ave.

This

dis

turb

ance is c

alle

d a

Gra

vity w

ave.

Pro

of of th

ese o

ccurr

ed in 1

974 b

y J

oseph

Pro

of of th

ese o

ccurr

ed in 1

974 b

y J

oseph

Taylo

r and R

ussell

Taylo

r and R

ussell

Huls

eH

uls

e..

To w

itness g

ravity w

aves y

ou h

ave to

To w

itness g

ravity w

aves y

ou h

ave to

make lots

of th

em

.m

ake lots

of th

em

.

Here

are

ways t

hey c

an b

e m

ade.

Here

are

ways t

hey c

an b

e m

ade.

Merg

ing n

eutr

on s

tars

.M

erg

ing n

eutr

on s

tars

.

Bla

ck h

ole

s e

ating n

eutr

on s

tars

.B

lack h

ole

s e

ating n

eutr

on s

tars

.

Tw

o m

erg

ing b

lack h

ole

s.

Tw

o m

erg

ing b

lack h

ole

s.

Implo

din

g s

tar

that cre

ate

s a

neutr

on s

tar

Implo

din

g s

tar

that cre

ate

s a

neutr

on s

tar

or

bla

ck h

ole

.or

bla

ck h

ole

.

LIG

OLIG

O

Laser

Laser

Inte

rfe

om

ete

rIn

terf

eo

mete

rG

ravitationa

l G

ravitationa

l

Wave O

bserv

ato

ry.

Wave O

bserv

ato

ry.

It o

pened in 2

002.

It o

pened in 2

002.

Lig

oLig

ois

ma

de o

f tw

o 4

km

lo

ng 4

fo

ot

is m

ade o

f tw

o 4

km

lo

ng 4

fo

ot

dia

mete

r vacuu

m p

ipe a

n a

L

dia

mete

r vacuu

m p

ipe a

n a

L

shape.

shape.

Ultra

sta

ble

laser

beam

s g

o thru

the p

ipes.

Ultra

sta

ble

laser

beam

s g

o thru

the p

ipes.

At all

four

ends a

re m

asses w

ith m

irro

rs o

n

At all

four

ends a

re m

asses w

ith m

irro

rs o

n

them

. T

hey m

easure

the c

hange in the

them

. T

hey m

easure

the c

hange in the

dis

tance b

etw

een the m

irro

rs.

dis

tance b

etw

een the m

irro

rs.

LIS

A Laser

inte

rfe

rom

ete

r S

pace

LIS

A Laser

inte

rfe

rom

ete

r S

pace

ante

nn

ae w

ill d

o t

he s

am

e.

ante

nn

ae w

ill d

o t

he s

am

e.

It is thre

e s

pace c

raft that fly in form

ation

It is thre

e s

pace c

raft that fly in form

ation

keepin

g a

n e

quila

tera

l shape.

keepin

g a

n e

quila

tera

l shape.