Quest For A Harp

Test Chamber 13: Place portals as shown in the image. Use a portal to move the laser sideways and a time portal to move it into the future. You may take some damage from the laser to travel into the future. Once in the future, rearrange portals so the laser goes directly into the target.

Test Chamber 14: First, take a time portal to the present. Summon a reflector cube from the switch in the center and position it in the present as shown. Use a portal to bring a laser through the first node, then use it to reflect the laser into the next two nodes. Travel to the future. Use portals as shown to bring a laser into the present through the time portal, ensuring it goes through the node. Pick up the reflector cube from the future and bring it into 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 and reposition the future reflector cube. Finally, place the future reflector cube at the end of the nodes in the future to reflect the laser into the receiver.

Test Chamber 15: Start by going through the particle field to 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 the future to bypass the particle field. Head to the other side of the room and use another time portal to return to the present, now on the other side of the particle field. Place a new portal on the upper wall above the laser room so the laser hits the first receiver. Travel back to the future and place a portal on the small wall in the laser room to shoot at the receiver. Return to the present. An elevating platform near the switch will power up. Stand on it and shoot a time portal behind the node to raise the platform further, allowing you to summon a reflector cube. Place this reflector cube on the lip above the second receiver. Travel to the future and pick up the future reflector cube. Place a time portal in the laser room in the present to bring the future reflector cube into the laser room. Position it to reflect the laser into the second receiver through the node. To get to the other side of the particle field without going through it, use a portal on the other side or a time portal. You need to be in the present on the other side of the particle field. Climb the stairs and use a portal on the upper wall to hit the third receiver. Move the reflector cube onto the switch to complete the test chamber.