The Missing Piece: Are Wormholes the Key to Time Travel?

Time travel -- it's a concept we're all too familiar with. From Hollywood Movies (shout out to Back to the Future) to theoretical physics, many theories have circulated regarding the bewildering topic of time travel. However, recently students at the California Institute of Technology1 have shed new light on a relatively dated theory: that wormholes may be the missing piece in the seemingly unsolvable puzzle behind time travel. So, step aside Doc Brown, because we're going to explore how a unique and mysterious part of our universe- the wormhole- connects to traveling through time!

Just like many principles in Physics, this concept finds its base in Einstein's Theory of General Relativity (for some background on this topic, view our previous blog post, "What happens to Matter inside a Black Hole?"). Basically, the theory attributes the characteristics of a wormhole to its incredibly high velocity. Similar to a black hole, a wormhole would compress an entering object to the size of a singularity and accelerate it to immeasurable speeds through the "throat" of the wormhole to the other side of the funnel. So, for now, think of a wormhole as a black hole that has a start and end point.2

Now, this is where the physics becomes complex. We know that a wormhole can basically "teleport" compressed objects at super speeds from one end to another, but how does that explain the time travel aspect? Well, the concept of time dilation can explain that. Time dilation is the relative difference in the passage of time between two entities due to a stark difference in either gravity or relative velocity. In the case of the wormhole, both are in play, which only compounds the effects. For a tangible example to grasp, let's look to the astronauts aboard the International Space Station. After 6 months aboard the ISS (where there is less gravity, but greater velocity of movement), these astronauts have actually aged .007 seconds less than the crew stationed on Earth.3 While this seems insignificant, we have to remember that because the velocity is increased but the gravity is decreased, each is actually mitigating the effects of the other. However, in a wormhole, where the effects of both gravity and velocity are exponentially amplified AND working in tandem, their relativistic effects are enormous.4

This graphic portrays an accurate depiction of velocities' effect on time dilation: http://upload.wikimedia.org/wikipedia/commons/7/72/Nonsymmetric_velocity_time_dilation.gif

Now that we have an understanding of time dilation, we want to leave you with this example. Imagine two test subjects at each side of a wormhole in the year 1995. One mouth of the wormhole has been accelerated to a point where relativistic effects (i.e. time dilation) apply significantly and the other mouth is stationary. When the two subjects pass through their respective mouths, they end up at where their counterpart stood... but at different times! The accelerated mouth would land its test subject in, let's say, 2000. However, the stationary mouth would place its test subject in a later year - we'll call it 2005- since the accelerated mouth exists in a different time caused by time dilation. The time travel becomes evident when we consider the following: what if the test subject who landed in 2005 stepped back into the mouth? They would end up in the year 2000, or 5 years in the past! A bit of manipulation, therefore, could technically transport this subject to any point in time between 2000 and 2005.5

Unfortunately, scientists have been unable to totally grasp how we could adapt the power of a wormhole into time machine-esq technology. We have yet to even theorize how we could accelerate a wormhole to relativistic speeds. Given that this is another theoretical aspect of our known universe, testing is extremely limited and all postulates have very little opportunity for tangible proof. What is certain, though, is that the advances we've made thus far in the field have brought us several pieces closer to solving the time traveler's puzzle!