Rising panic leadens your foot and you speed through the gloomy fog, unsure now whether you are running away from or toward danger. The van careens around a hairpin and the bottles rattle a chorus in the back. You glance hurriedly in the back to check for damage and when your eyes return to the road you stamp both feet on the brakes and the van screeches to a stop. One foot away, a glass bridge sways in the half-light, levitating as if supported by nothing but air. You unclench your death grip on the steering wheel and take deep breaths. What the hell is going on? Is this real? Is this a dream? You've got to make a judgement call. If you're hallucinating, you can continue driving on, confident that while you're quickly losing your mind, you remain on solid ground. But enough has happened tonight to give this apparition the benefit of the doubt. Gambling that it's solid might cause you to plunge to certain death. If you were smart, you'd turn around. What do you do?