We are nowhere close to running out of ideas. The real bottleneck for scientific research is not ideas, but money. We lack the funds to study everything that currently appears to be worth studying. As for the cutting edge of research, it really depends on which of the many sciences—and which of the many subdisciplines within those sciences—you want to know about. It’s a long list, and no one could possibly know what the cutting edge of each one is right now.