Test Chamber 04 introduces the concept of momentum preservation through portals, often referred to as 'portal flinging'. You'll see a large pit and a high platform on the other side. The key here is to gain speed before entering a portal. Place an orange portal on the floor at the bottom of the pit. Then, place a blue portal on a vertical wall directly opposite the high platform you need to reach. Jump into the orange portal in the pit. As you fall, you'll gain momentum. This momentum will be preserved when you exit the blue portal, launching you across the pit and onto the high platform. This technique is crucial for many later puzzles. Practice until you can consistently make the jump. Once on the platform, proceed to the exit.
