In this p
aper we discuss thermodyn
amics of
app
arent horizon of
an
n-dimension
al Friedm
ann–
Robertson–W
alker (FRW) universe embedded in
an <
a n
ame=""mml5"">
a><
a style=""text-decor
ation:none; color:bl
ack"" href=""/science?_ob=M
athURL&_method=retrieve&_udi=B6TVC-4P2
S921-5&_m
athId=mml5&_user=10&_cdi=5531&_rdoc=8&_
acct=C000050221&_version=1&_userid=10&md5=eb
a57de64
ad39
a8bb6d0
a0e7655f0592"" title=""Click to view the M
athML source"">(
n+1)
a>-dimension
al AdS sp
ace–time. By using the method of unified first l
aw, we give the explicit entropy expression of the
app
arent horizon of the FRW universe. In the l
arge horizon r
adius limit, this entropy reduces to the
n-dimension
al
are
a formul
a, while in the sm
all horizon r
adius limit, it obeys the <
a n
ame=""mml6"">
a><
a style=""text-decor
ation:none; color:bl
ack"" href=""/science?_ob=M
athURL&_method=retrieve&_udi=B6TVC-4P2S921-5&_m
athId=mml6&_user=10&_cdi=5531&_rdoc=8&_
acct=C000050221&_version=1&_userid=10&md5=6
a94
a3
a633d8155f933
aa825ce749ef1"" title=""Click to view the M
athML source"">(
n+1)
a>-dimension
al
are
a formul
a. We
also discuss the corresponding bulk geometry
and study the
app
arent horizon extended into the bulk. We c
alcul
ate the entropy of this
app
arent horizon by using the
are
a formul
a of the <
a n
ame=""mml7"">
a><
a style=""text-decor
ation:none; color:bl
ack"" href=""/science?_ob=M
athURL&_method=retrieve&_udi=B6TVC-4P2S921-5&_m
athId=mml7&_user=10&_cdi=5531&_rdoc=8&_
acct=C000050221&_version=1&_userid=10&md5=5bc9
ac47f673e2
ab
a7
ac84c3f78fc719"" title=""Click to view the M
athML source"">(
n+1)
a>-dimension
al bulk. It turns out th
at both methods give the s
ame result for the
app
arent horizon entropy. In
addition, we show th
at the Friedm
ann equ
ation on the br
ane c
an be rewritten to
a form of the first l
aw, <
a n
ame=""mml8"">
a><
a href=""/science?_ob=M
athURL&_method=retrieve&_udi=B6TVC-4P2S921-5&_m
athId=mml8&_user=10&_cdi=5531&_rdoc=8&_
acct=C000050221&_version=1&_userid=10&md5=5dc8044fbf094ec2b4fbb3918180ed04"">
ache/Mi
amiIm
ageURL/B6TVC-4P2S921-5-1T/0?wchp=dGLbVlb-zSkzV""
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athML source""
align=""
absbottom"" border=""0"" height=13 width=134>
a>,
at the
app
arent horizon.