We think of particle physics as making progress when we probe smaller
and smaller size scales, but sometimes new signatures can show up far
away from highly energetic particle collisions. I explain why Long Lived
Particles (LLPs) could be the harbingers of new physics beyond the
Standard Model, and why they are motivated by some of the most
fundamental mysteries in particle physics today, like the
Matter-Antimatter Asymmetry of the Universe, Dark Matter, and the
Hierarchy Problem. LLP signatures can be spectacular but are easily
missed in standard searches, which could be the reason that we have not
yet seen new physics at CERN's Large Hadron Collider. Exploring this
Lifetime Frontier requires new capabilities. I will introduce the
MATHUSLA proposal that aims to build a large but relatively simple
detector on the surface at CERN to catch these elusive LLPs, and also
discuss other detector proposals that MATHUSLA has inspired. Together,
these new experiments may hold the key to discovering the missing puzzle
pieces of new physics that could be hiding at the Lifetime Frontier.