Symbol k_B

The passage around this formula

with the proportionality constant fixed by the detector’s coupling strength and dimension — irrelevant here, since it cancels the instant the spectrum is normalized [ 1 , 5 ] . Takagi confirmed the same detailed-balance structure holds for a Rindler wedge of any spacetime dimension, which rules out the possibility that the thermal form is some low-dimensional accident of the four-dimensional calculation [ 7 ] . This is exactly the Planck spectral shape at temperature $T_U$ = $\hbar$ a/(2$\pi$ c $k_B$) , recovering the Unruh temperature as this article’s known-theory baseline, not as anything new.

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