OK, so ‘Monthly Mailbag’, might have been a slightly over-ambitious title. But we’re back answering questions from the comments section, this time on the topic of gravitational waves. Do the gravitational waves of black holes affect us here on Earth (0:27)? What’s the difference between gravitational fields and ethers (1:15)? Why do we think gravitons should exist (2:53)? Does the Earth’s weight change over time (3:53)? Jon explains all. Watch Sheila Rowan’s full lecture on Catching Gravitational Waves here: https://youtu.be/P9k4FP_b1fo After Sheila’s talk, there were loads of great questions about the nature of gravity and gravitational waves. This month, Jon dives into the murky waters of the comments section to explain a few of the finer points. Watch the previous episode, with Kate talking about nitrogen triiodide and multiverses, here: https://youtu.be/BeRl5aVIrVo Subscribe for regular science videos: http://bit.ly/RiSubscRibe The Ri is on Twitter: http://twitter.com/ri_science and Facebook: http://www.facebook.com/royalinstitution and Tumblr: http://ri-science.tumblr.com/ Our editorial policy: http://www.rigb.org/home/editorial-policy Subscribe for the latest science videos: http://bit.ly/RiNewsletter