What Is The Universe? Also, 'Top Chef' Judges Talk About Spanish Food

• Tuesday, April 7: Fans ofTop Chef , you remember guest judge Wylie Dufresne -- he runs WD-50 in NYC, and is famous for experimental molecular gastronomy. Well, he'll be here in DC alongside tapas genius Jose Andres at the National Museum of American History to talk about Spanish food. No free samples, sorry. [ Smithsonian ]

• Thursday, April 9: If you're one of those people who thinks humans live inThe Matrix , perhaps you need to attend Dr. Vera Rubin's lecture about the Universe at the Air and Space Museum. She's from the Carnegie Institute so she knows her stuff, but don't expect her to solve your existential crises for you. 6PM. [ Air and Space ]

• Tuesday, April 14: Jazz guitarist Bucky Pizzarelli and trumpeter Joe Wilder (who's played with Louis Armstrong and Billie Holiday) perform at the National Museum of American History in celebration of Jazz Appreciation Month. [Smithsonian ]

• Tuesday, April 14: There are many things that are annoying about DC's street system: the circles, the "grid" system (if you can even call it that), the whole NE/SE/SW/NW business, and the fact that there's no J St. Architectural critic Robert Campbell ofThe Boston Globe will take a look at how DC should "balance the need for security with accessibility, transparency, and aesthetics." $20, 6: 30PM. [ National Building Museum ]

• Awesome pictures of orchids at the National Museum of Natural History's exhibit, Orchids Through Darwin's Eyes . Until April 26. [ Washington City Paper ]