In[]:=
eqlist={(Quantity[(4π)/tNow,1/("Seconds")])Sin[(9.419*10^-21tNow)/ Sqrt[1/CMBRTempAtStart^4]]== Quantity[(37π)/48469710106800000000,1/("Seconds")],1/(22^(1/4) Sqrt[π])(((1+ Cos[(2.9592*10^-20tNow)/Sqrt[1/ CMBRTempAtStart^4]])(Quantity[ 6.399*10^59,("Kelvins")^4("Meters")^2]))/(Cos[( 9.419*10^-21tNow)/Sqrt[1/ CMBRTempAtStart^4]](Quantity[-3.9996*10^29Sqrt[1/ CMBRTempAtStart^4],"Meters"])+ Quantity[4.636*10^29Sqrt[1/CMBRTempAtStart^4],"Meters"])^2)^( 1/4)==Quantity[2.73,"Kelvins"]}
Out[]=
Sin,
9.419×tNow
-21
10
1
4
CMBRTempAtStart
1
2
1/4
2
π
1/4
1+Cos
2.9592×tNow
-20
10
1
4
CMBRTempAtStart
2
Cos+
9.419×tNow
-21
10
1
4
CMBRTempAtStart
In[]:=
FindRoot[eqlist,{{tNow,5*356.25*3600*24*10^10},{CMBRTempAtStart,3}}]
18
10
18
10
18
10
18
10
18
10
Out[]=
FindRoot[eqlist,{{tNow,5×356.25×3600×24},{CMBRTempAtStart,3}}]
10
10
18
10
18
10
18
10