A cosmic puzzle: A new version of Einstein's cosmological constant may possibly show the way to overcome general relativity.
Holographic Universe: Some theoretical results about black holes suggest that the Universe could resemble a giant hologram.
The illusion of gravity: The force of gravity and one of the dimensions of space may be generated by peculiar interactions of particles and fields in a World with fewer dimensions.
Variable constants: Do the inner workings of Nature change over time?
The landscape of string theory: String theory predicts that the Universe may occupy some random "valley" from an almost infinite collection of valleys in an endless "landscape" of possibilities.
The atoms of space and time: We perceive space and time as continuous, but if the fascinating theory of quantum gravity loops is true, then in reality space and time exist in the form of discrete pieces.
Parallel universes: They are not only in scientific imagination; they are a direct consequence of cosmological observations.
The myth of the beginning of time: According to string theory, the Big Bang was not the beginning of the Universe but simply the natural consequence of a pre-existing state.