Why don’t we have a theory of quantum gravity yet? I explore why it has been so difficult. Check out this video's sponsor https://brilliant.org/dos Our best theories of physics are incomplete, quantum mechanics and general relativity don’t work when we try and put them together so physicists have been looking for a grand unifying theory of quantum gravity for decades, and so far have failed. This is because it is virtually impossible to make an experiment where the large and small scales meet, so we look to the places in our universe where this happens naturally: black holes and the big bang via the cosmic microwave background. In this video I explain what our best theories are and how we are trying to get to a theory of quantum gravity. #quantumgravity #ThreeByThree #DomainOfScience If you’d like to support my free educational content: https://www.patreon.com/domainofscience -- Posters --- DFTBA Store: null RedBubble Store: https://www.redbubble.com/people/DominicWalliman I have also made posters available for educational use which you can find here: https://www.flickr.com/photos/95869671@N08/ - Some Awesome People -- And many thanks to my $10 supporters on Patreon, you are awesome! Theodore Chu Sebastian Eric Epstein Alex Polo Join the gang and help support me produce free and high quality science content: https://www.patreon.com/domainofscience -- My Science Books --- I also write science books for kids called Professor Astro Cat. You can see them all here: http://profastrocat.com/ -- Follow me around the internet -- http://dominicwalliman.com/ https://twitter.com/DominicWalliman https://www.instagram.com/dominicwalliman -- Credits -- Sound effects obtained from https://www.zapsplat.com/ Music by Dominic Walliman