Forward to the past? Backward to the future? Sure, it happens in the movies, but could real-world physics tell us anything about the possibility of human time travel in the near future?

Curiosity contributor Susan Sherwood examined the mind-blowing possibilities of time travel via quantum foam and came up with the following answer.

Time travel through wormholes is theoretically possible under the known laws of physics, and quantum foam may be one piece of that puzzle. What is this foam? How could it work? We have to delve into the tiny world of quantum mechanics for some answers.

The basic laws of Newtonian physics cover what we can see every day with our eyes: If you let go of a book, it will fall; push a ball and it will roll. Quantum mechanics concerns the tiniest, unseen parts of the world, parts even smaller than subatomic particles. Measuring things on that scale is tricky, and the smallest measurement used by physicists is the Planck length, written as a one preceded by 34 zeros and a decimal point. This is the size of the smallest particles that compose the fabric of space-time [source: Johnson].

At this miniscule scale, it is theorized that tiny particles or black holes are fluctuating -- appearing and disappearing. This churning mix of particles is called quantum foam. To visualize it, imagine a swimming pool full of boiling water. Up close, you can see frothing and bubbles bursting, but if you viewed a satellite photo of the pool, the surface would appear unbroken. That's a comparison between what might be happening at the subatomic level and what we see with our eyes according to the theory of quantum foam.

What does this have to do with wormholes? It is within quantum foam that wormholes are theoretically believed to exist. They can move in and out of existence, connecting different places and times. Since they are so incredibly small, humans couldn't use them for time travel. Some theoretical physicists, though, are exploring the concept of a wormhole time machine -- the idea being that a wormhole might be ensnared and expanded until it could become a transit for time travelers [source: Hawking].

This is still in the hypothetical stages, of course. However, a scientist at the University of Maryland believes he can create a substance in a laboratory that mimics quantum foam [source: Technology Review]. This kind of study may help move quantum foam from a theoretical entity to a known quantity. Would H. G. Wells' Time Machine (1895) then be far behind?