Extra Dimensions in Cosmology: "If modern physics has taught us anything, it is that our normal intuition of how the universe works cannot be trusted. A perfect example is Einstein’s Special Theory of Relativity, which states that the speed of light is the only constant, length and time can vary, and our notion of the simultaneity of two events is incorrect. Another example is quantum mechanics, which says that properties of an object such as momentum and position cannot be determined precisely, only probabilistically. A concept regarding the structure of the universe that again opposes our instincts is that of extra dimensions."