  We give a new proof, independent of Lin's theorem, of the Segal conjecture
for the cyclic group of order two. The key input is a calculation, as a Hopf
algebroid, of the Real topological Hochschild homology of $\mathbb{F}_2$. This
determines the $\mathrm{E}_2$-page of the descent spectral sequence for the map
$\mathrm{N}\mathbb{F}_2 \to \mathbb{F}_2$, where $\mathrm{N}\mathbb{F}_2$ is
the $C_2$-equivariant Hill--Hopkins--Ravenel norm of $\mathbb{F}_2$. The
$\mathrm{E}_2$-page represents a new upper bound on the $RO(C_2)$-graded
homotopy of $\mathrm{N}\mathbb{F}_2$, from which the Segal conjecture is an
immediate corollary.
