"Brave New World" is the fourth episode of the fifth season of Grey's Anatomy and the 82nd produced episode of the series. It is also the 93rd produced episode of the Grey's Anatomy franchise. It was broadcast on October 16, 2008.
Cristina discovers a new part of the hospital that neither she nor her fellow residents had seen before as Meredith gets upset when Derek finds her mother's diary resurfacing her complexion about measuring up to her mother's surgical skill. George and Lexie await news about the results his intern exam and Callie grows nervous about her first official date with Erica. Izzie is forced to fight back when Alex steals her surgery.
- "In 6,500 B.C, some guy looked at his sick friend and said 'I have an idea, why don't I drill a hole in your dead, it'll make you feel better'. And thus, surgery was born. It takes a certain brand of crazy to come up with an idea like drilling into somebody's skull but surgerons have always been a confident bunch. We usually know what we're doing and when we don't we still act like we do. We walk boldly into undiscovered country, plant a flag and start ordering people around. It's invigorating and terrifying."
- "We like to think we're fearless, eager to explore unknown land and soak up new experiences. But the fact is we're always terrified. Maybe the terror is part of the attraction. Some people go to horror movies, we cut things open. Dive into dark water. And at the end of the day isn't that what you'd rather hear about. If you've got one drink and one friend and forty-five minutes, smooth rides make for boring stories. A little calamity, that's worth talking about."
- "Altogether Now" - Patrick & Eugene
- "My Love" - The Bird And The Bee
- "Big Jumps" - Emiliana Torrini
- "Done With You" - The Whitest Boy Alive
- "One Of Those Days" - Joshua Radin
- "Ain't Gonna Lose You" - Brett Dennen
- "Love To Me" - Bernadette Moley
- "My Heart With You" - The Rescues
This episodes' title references the song Brave New World, originally sung by Iron Maiden