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Cosmological time dilation
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Past exam of the mathematics course of the University of Cambridge
/
2001
/
iii
/
Paper 41
/
1
/
ii
/
Solution
2026-10-03
0
Past exam of the mathematics course of the University of Cambridge
/
2001
/
iii
/
Paper 41
/
1
/
i
/
Solution
2026-10-03
0
Past exam of the mathematics course of the University of Cambridge
/
2001
/
iii
/
Paper 67
/
1
/
ii
/
Solution
2026-10-03
0
Past exam of the mathematics course of the University of Cambridge
/
2008
/
iii
/
Paper 73
/
1
/
iii
/
Solution
2026-10-03
0
Past exam of the mathematics course of the University of Cambridge
/
2025
/
ii
/
Paper 1
/
9E
/
b
/
Solution
Created
2026-09-24
Updated
2026-10-03
View more
Each
photon
loses
a
factor
(
1
+
z
)
−
1
in
energy
, and
cosmological time dilation
reduces the
photon
arrival rate by another factor
(
1
+
z
)
−
1
. Hence
L
received
=
(
1
+
z
)
2
L
,
(1)
so
n
=
2
. The physical
area
of the
sphere
today is
4
πa
(
t
0
)
2
x
2
,
giving
flux
F
=
4
πa
(
t
0
)
2
x
2
(
1
+
z
)
2
L
.
(2)
Total
articles
:
5
