• Question: Can gravitational waves be created? If yes, how?

    Asked by anonymous to Steve, Emma, Christian, Bose, Alice on 9 Mar 2016.
    • Photo: Alice Harpole

      Alice Harpole answered on 9 Mar 2016:

      A gravitational wave is caused by massive accelerating objects distorting spacetime. So, you could make one right now just by waving your arm about, but it would be incredibly weak. Gravity is much, much weaker than the other forces, so to make a gravitational wave strong enough for us to detect, you need some of the most extreme events we know if in the universe, eg the collision of black holes.

    • Photo: Steve Marsden

      Steve Marsden answered on 10 Mar 2016:

      Spot on, what Alice said.

      I just wanted to stress how incredibly weak they are. We recently measured gravitational waves for the first time. The wave we measured was created by two black holes colliding, and merging together. The amount of energy released in the event, and contained within the wave was 10^47 J. In order to emit the same amount of energy as light, it would take our entire galaxy more than 300 years! This was an incredibly powerful event, and using the most sophisticated and sensitive techniques we know, we could only just measure it.

      If you wanted to create your own gravitational waves, and for them to be measurable, you’d need to convert the energy output of hundreds, if not thousands of galaxies!

    • Photo: Christian Killow

      Christian Killow answered on 16 Mar 2016:

      Nothing to add to the answers already given, except that you ask a good question – scientists were asking this question a few decades ago! It would have been nice to have a piece of kit in the lab to test the detectors with. Alas, they soon realised that you would need to move so much mass around that it was even harder than building a detector!

Comments