Jet Belt

Test Chamber 13: Place portals as shown to redirect the laser. Use a time portal to move the laser into the future. Enter the time portal yourself, potentially taking some damage, to reach the future. Rearrange portals in the future to direct the laser into the target, then exit through the door.

Test Chamber 14: Travel to the present via a time portal. Summon a reflector cube and position it in the present as indicated. Use a portal to bring a laser through the first node, then use the reflector cube to direct it into the next two nodes. Travel to the future. Use portals to bring a laser into the present through the time portal, ensuring it passes through the node. Retrieve the reflector cube from the future and bring it to the present via a time portal. Position the present reflector cube to hit all three nodes. If necessary, travel back to the future to retrieve the future reflector cube again. Finally, position the future reflector cube to reflect the laser into the receiver to complete the chamber.

Test Chamber 15: Enter the particle field on the left. Place a portal where the laser hits the wall and a time portal on the opposite wall. Travel through the time portal to reach the future, bypassing the particle field. Proceed to the other side of the room and use another time portal to return to the present, now on the correct side of the particle field. Place a new portal on the upper wall to direct the laser to the first receiver. Travel to the future and place a portal in the laser room to shoot at the receiver. Return to the present; the laser should now be powering an elevating platform. Stand on the platform and place a time portal behind the node to raise it further, allowing you to summon a reflector cube. Place this reflector cube on the lip above the second receiver. Travel to the future. Retrieve the future reflector cube and bring it back to the present using a time portal within the laser room, positioning it to direct the laser to the second receiver through the node. Now, get to the other side of the particle field without passing through it (use existing portals or a time portal). Climb the stairs and place a portal on the upper wall to hit the third receiver. Move the reflector cube onto the switch to complete the chamber.