diff --git a/book/knowledge-library/alcubierre-metric-intro.ipynb b/book/knowledge-library/alcubierre-metric-intro.ipynb index a6cd715..cfc2929 100644 --- a/book/knowledge-library/alcubierre-metric-intro.ipynb +++ b/book/knowledge-library/alcubierre-metric-intro.ipynb @@ -167,7 +167,7 @@ "id": "09e2456a", "metadata": {}, "source": [ - "Now, we can calculate the expansion and contraction of space resultant from the metric - the magnitude of which is termed the **York Time**. The trace of the extrinsic curvature tensor $K_{ij}$ is given by:" + "Now, we can calculate the expansion and contraction of space resultant from the metric - the magnitude of which is termed the **York Time**. The trace (contraction) of the extrinsic curvature tensor $K_{ij}$ is given by:" ] }, { @@ -176,7 +176,7 @@ "metadata": {}, "source": [ "$$\n", - "K^i{}_j = \\partial_j X^i\n", + "K = K^i{}_i = \\partial_i X^i\n", "$$" ] }, @@ -194,7 +194,7 @@ "metadata": {}, "source": [ "$$\n", - "K^i{}_j = v_s \\frac{x_s}{r_s} \\frac{df(r_s)}{dr_s}\n", + "K = v_s \\frac{x_s}{r_s} \\frac{df(r_s)}{dr_s}\n", "$$" ] }, @@ -334,7 +334,7 @@ "metadata": {}, "source": [ "$$\n", - "T_{00} = -\\frac{1}{8\\pi} \\frac{(v_s)^2 (y^2 + z^2)}{4 (r_s)^2} \\left(\\frac{df(r_s)}{dr_s}\\right)^2\n", + "T_{00} = \\frac{1}{8\\pi} G^{00} = -\\frac{1}{8\\pi} \\frac{(v_s)^2 (y^2 + z^2)}{4 (r_s)^2} \\left(\\frac{df(r_s)}{dr_s}\\right)^2\n", "$$" ] }, @@ -344,7 +344,7 @@ "metadata": {}, "source": [ "```{note}\n", - "Here $G = c = 1$, which is the standard when using the ADM formalism.\n", + "Here $G = c = 1$, which is the standard when using the ADM formalism. Thus $\\frac{c^4}{8\\pi G} \\Rightarrow \\frac{1}{8\\pi}$.\n", "```" ] },