The urge to hug a departed loved one again or prevent atrocities are among the compelling reasons that keep the notion of time travel alive in the minds of many.

While the idea makes for great fiction, some scientists now say traveling to the past is impossible.
There are a handful of scenarios that theorists have suggested for how one might travel to the past, said Brian Greene, author of the bestseller, “The Elegant Universe” and a physicist at Columbia University.“And almost all of them, if you look at them closely, brush up right at the edge of physics as we understand it. Most of us think that almost all of them can be ruled out.”

In physics, time is described as a dimension much like length, width, and height. When you travel from your house to the grocery store, you’re traveling through a direction in space, making headway in all the spatial dimensions—length, width and height. But you’re also traveling forward in time, the fourth dimension.

“Space and time are tangled together in a sort of a four-dimensional fabric called space-time,” said Charles Liu, an astrophysicist with the City University of New York, College of Staten Island and co-author of the book “One Universe: At Home In The Cosmos.”

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See also under de “science section” a documentary

First gravity and now this ... thanks, scientists. Ruining all of my childhood dreams ... *sits in corner and cries*

Oh, and if time is the fourth dimension, and movies take time, does that mean that there are people watching 4D movies?

That depends.  If you’re watching anything with Brad Pitt then it’s only a 3D movie since it won’t have any depth to it.

“Space and time are tangled together in a sort of a four-dimensional fabric called space-time,”

but isn’t this still based on OUR understanding of physics?  And if it does tangle together, then it holds that it’s not only possible to travel back in time, but forward AND into time that ‘isn’t’