TITLE: Is the infimum of Salem numbers > 1?
QUESTION [9 upvotes]: BACKGROUND
A Salem number is an algebraic integer $\theta$ such that all the Galois conjugates of $\theta$ are $\leq 1$ in absolute value, and at least one of them lies on the unit circle. Their importance is derived for example from the fact that the minimal polynomial of a Salem number, 
$$
P(x) = x^{10} + x^9 - x^7 - x^6 - x^5 - x^4 - x^3 + x + 1
$$ 
is conjectured to minimize the Mahler measure ($M(P) = 1.17...$) over all $P \in \mathbb{Z}[x]$ with $M(P) > 1$. 
The closely related Pisot numbers are algebraic integers $\theta > 1$ such that all the Galois conjugates of $\theta$ are of absolute value $< 1$. Their set is closed and in particular there exists a smallest Pisot number. This has been found by Siegel to be the plastic constant, $\theta_0 = 1,32471\ldots$, a root of $g(x) = x^3 - x - 1$. It is known that for any monic, non-reciprocal polynomial $P$ we have $M(P) \geq M(g) = \theta_0$. This is Smyth's theorem.
THE QUESTION
I am currently reading ``Conjecture de Lehmer et petits nombres de Salem" by Bertin and Pathiaux-Delefosse. The book is from 1989 and it is stated in it that it is still not known if $\inf T > 1$ where $T$ is the set of all Salem numbers.  Has there been any developments since then? Is this conjecture still open?
Precisely: Has it been proved or disproved that $\inf T> 1$?

REPLY [3 votes]: Just wanted to add: the conjecture that Salem numbers are bounded away from one (the "Salem Conjecture") is wide open as the other answers state, and it's equivalent to part of what is known as the "Short Geodesic Conjecture" for hyperbolic orbifolds: that there is a positive universal lower bound for the lengths of geodesics in arithmetic hyperbolic 2-orbifolds.  The case of 3-orbifolds implies the Salem Conjecture.  You can find this information in Maclachlan and Reid's book The Arithmetic of Hyperbolic 3-Manifolds, Section 12.3, along with some comments on the Salem Conjecture.