Rainer "Rai" Weiss (; Jamusanci: [vaɪs]; an haife shi a ranar 29 ga Satumba, 1932) wani masanin kimiyyar lissafi ne na Amurka, wanda aka sani da gudummawar da ya bayar a fannin kimiyyar lissafi da ilimin lissafi. Shi farfesa ne na ilimin lissafi a MIT kuma farfesa mai ba da taimako a LSU. An fi saninsa da ƙirƙirar fasahar laser interferometric wanda shine ainihin aikin LIGO. Ya kasance Shugaban Kungiyar Kungiyar Kimiyyar Kimiyyar COBE. Shi memba ne na gwajin Fermilab Holometer, wanda ke amfani da laser interferometer 40m don auna kaddarorin sararin samaniya da lokaci a sikelin kwantum da kuma samar da gwaje-gwajen Planck-precision na canjin holographic na kwantum. A shekara ta 2017, an ba Weiss lambar yabo ta Nobel a fannin kimiyyar lissafi, tare da Kip Thorne da Barry Barish, "don gagarumar gudummawa ga mai gano LIGO da kuma lura da raƙuman nauyi.
MIT da kuma farfesa a LSU