Does anyone here know if it would be theoretically possible for humans to harness the energy from gravitational waves?
A device like a speaker (conceptually) might be able to be driven by a gravitational disturbance and store the energy. Let's assume that you somehow managed to build one. Now, imagine tidal power, but you've thrown a pebble into a pond. By the time gravitational waves reach Earth, they are so faint that detecting them has been extremely difficult, so harnessing them for energy isn't really feasible. If you were to send some type of device near an event like a black hole merger, you could possibly store some energy. The problem is, you would have to expend so much energy to get anything there and back, it might not be a net gain, certainly not with today's technology. Entertaining thought though. :)
This may not be entirely relevant to your question, but I think it warrants being said. To my understanding, this discovery is significant because it provides evidence for so called 'primordial' gravity waves, caused by inflation in the early universe. We already have some evidence for gravity waves in general, as we have detected them in the orbital decay of some pulsars. So, I would say that we could not harness these types of waves, if only because of the nature of their origin.
Also, could we negate gravitational waves, in the same manner as noise cancellation technology?