Dark Energy

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hi guys,

I have a question about computing reimann tensor in general relativity.

suppose we have schwarzschidl metric: ds^2=-(1-2*m*(r^-1))*dt^2+(1-2*m*(r^-1))^(-1)*dr^2+r^2*dtheta^2+r^2*sin^2(theta)*dphi^2.

I want to caclulate R[alpha,beta,mu,nu]*R[~alpha,~beta,~mu,~nu] where R[alpha,beta,mu,nu] is covariant form of Reimann tensor and also R[~alpha,~beta,~mu,~nu] is the contravariant form of Riemann tensor. I also want to calculate same thing for weyl tensor. please guide me.

with best regards.

hello guys,

I want to plot the phase plane between F and m when:

F := 736*R^4/sqrt((-1380*Pi*R*m(r)^3 + 368*R^4 - 1587*m(r)^2*R^2 + 1280*m(r)^2*a)^2);
R := X^(1/3)/(-l^2 + 4*a) - 3*l^2*m(r)^2/X^(1/3);
X := m(r)*l^2*(sqrt((27*l^2*m(r)^4 - 16*a^2*l^2 + 64*a^3)/(-l^2 + 4*a)) + 4*a)*(-l^2 + 4*a)^2;


m := (l^2*r^2 + r^4 + a*l^2)/(2*l^2*r)

for positive constant a and l

please guide me,


Hi guys

I want to solve the following non-linear differential equation but by using dsolve(), the computer cannot solve it, so please guide me.

Q:=2*diff(a(t), t, t)*a(t)^3 - 3*diff(a(t), t)^4 + diff(a(t), t)^2*a(t)^2

with the best regards

Hi guys,

I want to solve the matrix equation. suppose we have a matrix A 4*4 which only first array of it (1,1) is equal to n and another matrix such as S which is again 4*4 and generally, we don't know its arrays and we want A and S satisfy the following equation:


how we can find out arrays of S?







I want to find abs(psi)^2 for below psi

psi=int(int(exp(-a*(mu-b)^2)*exp(-c*(V-d)^2)*exp(I*(Q*u-(5/3*Q)*v^(mu/V)-3/16*(v^(4/V)/Q)))*v^((1/2)*(1-V)/V), mu = 0 .. 2), V = -15 .. 15) when mu=0..2 and V=-15..15 for Q:=3, a=10, c=5, b=3 and d=0.

unfortunatelly, I write above psi in maple 18 but it does not work, please tell me how to calculate (abs(psi))^2 for above wave equation (psi).

with the best regard.

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