Java Hangs When Converting 2.2250738585072012e-308. PHP too. The solution to the puzzle in both cases: the number is the smallest representable number in double floats and approximations are determined for the conversion in Java and PHP, but unfavorable values are assumed as starting points - and thus infinite loops result because the target value is never reached. And yes, this is critical because you can send servers into a loop if you enter these number values in input fields that convert to double float. I also tried it with Python (CPython and PyPy), but they don't run into a loop, they simply deliver a slightly different value.