a series of events triggered by one event
цепная реакция событий, вызванных одним событием (tsepnaya reaktsiya sobytiy vyzvannykh odnim sobytiyem)
"One breakthrough can start a chain reaction of new innovations."
"Одно открытие может вызвать цепную реакцию новых инноваций." (odno otkrytiye mozhet vyzvat tsepnuyu reaktsiyu novykh innovatsiy)
to become extremely popular online
to keep working steadily on something
to find a satisfactory compromise between two things
to be cheerful and confident
You said exactly what I was thinking
No matter how bad things look, you can still hope.