The concept of time as a way to measure the duration of events is not only deeply intuitive, it also plays an important role in our mathematical descriptions of physical systems. For instance, we define an object’s speed as its displacement per a given time. But some researchers theorize that this Newtonian idea of time as an absolute quantity that flows on its own, along with the idea that time is the fourth dimension of spacetime, are incorrect. They propose to replace these concepts of time with a view that corresponds more accurately to the physical world: time as a measure of the numerical order of change.
posted by finite on Apr 25, 2011 - 127 comments

Rules for Time Travelers [Spoiler? alert.]
posted by BitterOldPunk on May 14, 2009 - 82 comments

These subjects still fascinate me after a lifetime of interest: faster-than-light speed, alternate time streams, parallel universes, time travel, antiparticles moving backward in time, time loops, and the recurring themes of paradox -- all serious but astonishing ideas of science. Something about them inspires infinite possibilities. Am I not alone?
posted by ember on Mar 12, 2009 - 64 comments

Time Travel, or, the art of causing events after they've already happened. [requires java, more inside]
posted by Avenger on Jul 23, 2007 - 34 comments

A bold paper published in the August issue of Foundations of Physics Letters seems set to change the way we think about the nature of time and its relationship to motion and classical and quantum mechanics. The work also appears to provide solutions to Zeno's paradoxes. (Via Kurzweilai.net. More inside...)
posted by Pinwheel on Aug 1, 2003 - 41 comments