Asking the big questions about physics. What if...? are the two words that sow the seeds for human speculation, experimentation, invention, evolution, revolution, and change. In an uncertain age, economists are asking, What if growth stopped growing?; scientists, What if light speed were overtaken?; and politicians, What if the third world became the first? What If Einstein Was Wrong? challenges a team of scholars to experiment with 50 topical science speculations, at a time when the hunt for the Higgs boson particle is threatening to undermine the foundations of our knowledge. You can consider what time travel, warp speed, artificial gravity, or the loss of Schrodinger's cat could mean to us, and en route accumulate the knowledge you need to debate the shape that our science might take in the future.