ISSN 0002-9920 (print) ISSN 1088-9477 (online) of the American Mathematical Society February 2018 Volume 65, Number 2 In Honor of Black History page 118 Proof of a Null Geometry Penrose Conjecture page 156 Nashville Meeting page 220 Portland Meeting page 224 Boston Meeting page 229 A MERICAN M ATHEMATICAL S OCIETY Support AMS Mathematics Research Communities 2016 MRC participants at work. Photo by Mike Breen Your gift builds strong research networks, assists early- career mathematicians, and helps mathematics advance. Mathematics Research Communities (MRCs) develop cohorts for collaborative research among early-career mathematicians through summer conferences, special sessions at meetings, discussion networks, and more. The AMS is grateful for the partial funding support from the National Science Foundation and for the generosity of individual donors who extend the reach and impact of the MRCs. To donate visit www.ams.org/support-mrc Contact the AMS Development Offi ce by phone: 401-455-4111 or email:
[email protected] Notices of the American Mathematical Society February 2018 FEATURED t¯ y¯ x¯,¯z E (Σs ) → E H � t 118684 156 y 26164 x,z In Honor of Black History Proof of a Null Geometry Graduate Student Section Interview with Chelsea Walton ( ) → Penrose Conjecture by Talithia Williams, Arlie O. Petters,EH Σs M Conducted by Alexander Diaz-Lopez Erica Graham, Raegan Higgins, by Hubert L. Bray and Henri P. Roesch Candice Price, Shelby Wilson, David WHAT IS...the Amplituhedron? Goldberg, Phil Kutzko,Talitha M. by Jacob Bourjaily and Hugh omas Washington, Asamoah Nkwanta, Janet E. Barber, Johnny L. Houston, Edray AMS Graduate Student Blog Herber Goins, and Vernon R.