LET'S START WITH an exercise. Hold your index finger out in front of you. Now draw a cube in the air. Think about how you drew that cube: Did you draw a flat cube with a square and diagonal lines to simulate a three-dimensional drawing on a two-dimensional plane? Or did you outstretch your arm to give your cube depth, extending into the third dimension? Chances are if you are an adult, you drew a flat cube. When I try this exercise with young children, they don't have the limitations of thinking about 3D objects as a 2D representation. They think about things how they are in the physical world. We have spent our entire lives viewing content on flat paper, a computer screen, a phone, and it's very difficult to reverse that mentality. But my hope for you is that you can train yourself to think like a child. To think in a more physical way. Because to create virtual worlds, we must drop much of what we've been taught all our lives. We need to remove the limitations that decades of schooling and society have engrained in our minds. It can be done, but it takes work to break those mental habits.

When we work in extended reality, many of the constraints that exist for other media are lifted. The laws of physics no longer exist (unless you want them to). Some of the best features of development engines such as Unity and Unreal are that they simulate physics—gravity, collision, motion, etc. However, these programs also allow you to turn physics off or adapt the experience ...

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