Source code for einsteinpy.symbolic.predefined.de_sitter
from sympy import cos, cosh, diag, exp, sin, sinh, symbols
from einsteinpy.symbolic.metric import MetricTensor
[docs]
def AntiDeSitter():
"""
Anti-de Sitter space
Hawking and Ellis (5.9) p131
"""
coords = symbols("t chi theta phi")
t, ch, th, ph = coords
metric = diag(
-1,
cos(t) ** 2,
cos(t) ** 2 * sinh(ch) ** 2,
cos(t) ** 2 * sinh(ch) ** 2 * sin(th) ** 2,
).tolist()
return MetricTensor(metric, coords, "ll", name="AntiDeSitterMetric")
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def AntiDeSitterStatic():
"""
Static form of Anti-de Sitter space
Hawking and Ellis (5.9) p131
"""
coords = symbols("t r theta phi")
t, r, th, ph = coords
metric = diag(-cosh(r) ** 2, 1, sinh(r) ** 2, sinh(r) ** 2 * sin(th) ** 2).tolist()
return MetricTensor(metric, coords, "ll", name="AntiDeSitterStaticMetric")
[docs]
def DeSitter():
"""
de Sitter space
Hawking and Ellis p125
"""
coords = symbols("t x y z")
t = coords[1]
al = symbols("alpha")
expr = exp(2 * t / al)
metric = diag(-1, expr, expr, expr).tolist()
return MetricTensor(metric, coords, "ll", name="DeSitterMetric")