On me, going up forever never gets you higher. Going down forever never gets you lower. I exist in art but not in physics. What am I?

Question

Accepted Answer

An Escher Staircase (Penrose Steps). The Penrose steps, made famous by M.C. Escher's lithograph 'Ascending and Descending', depicts a staircase that appears to continuously ascend or descend in a loop — an impossible object that exists in two-dimensional art but cannot be built in three-dimensional reality.

"On me, going up forever never gets you higher. Going down forever never gets you lower. I exist in art but not in physics. What am I?"

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