I've read Isaac Newton stuttered, how accurate that is I couldn't really tell you. I'm no scientist, but I'm a journalism major. With that comes a lot of writing, which I personally love doing. But with writing, comes interviewing people, in person, via email, and sometimes even through the dreaded telephone. I've spoken to other journalists who stutter and their stories are incredible. One person I've spoken to recently moved to another country to work as a journalist, completely stepping out his comfort zone, like a fish out of water, immersing himself in numerous social situations, interviewing authority figures and the like. I'm sure there are other scientists who stutter, but what you're experiencing is something we all go through, and that's no rocket science. You CAN handle the pressure of presentation after presentation. You'll struggle along the way - they'll be a lot of trial and error - but consider this: You've done your research, you're clearly an intelligent individual and you know your shit. Practice makes perfect right? I know firsthand how discouraging it can be. It may not come out as perfectly as you'd like or imagined in your head, but if you research and prepare, you'll be okay. Try practicing in front of a mirror, or with people who understand you. It would be a real big shame if the world didn't hear what you had to say, especially since you love sharing what you've done. Hang in there and props on that PhD! One day you'll discover something epic and we'll see your selfie right up there next to all those famous people who stutter.