Observations show the universe appears flat, yet its true size and global shape beyond the observable horizon may remain forever unknown.

For more than a century, physicists have suspected that the familiar three dimensions of space might be only a small slice of reality. The idea that the universe could be hiding several additional ...

In 1919, physicist Theodor Kaluza hypothesized that extra dimensions might solve some outstanding problems in physics. And while we haven't found any evidence yet for anything outside our normal ...

Add Yahoo as a preferred source to see more of our stories on Google. In space, there are four dimensions: length, width, height and time. scaliger/iStock/NASA via Getty Images Plus About a century ...

Physicists have taken a bold step beyond Einstein's special theory of relativity, proposing an expansion of special relativity that includes observers moving faster than light. This fresh perspective ...

Physicists who work with a concept called string theory envision our universe as an eerie place with at least nine spatial dimensions, six of them hidden from us, perhaps curled up in some way so they ...

Time, not space plus time, might be the single fundamental property in which all physical phenomena occur, according to a new theory by a University of Alaska Fairbanks scientist. The theory also ...

Physicists are scrambling to understand why dark energy is weakening. In a surprising twist, we must now reconsider the ...