Scientists have proposed using “wormholes” as a time machine. A wormhole is a theoretical entity in which space-time curvature connects two distant locations (or times). Although we do not have any concrete evidence that wormholes exist, we can infer their existence from Einstein’s general theory of relativity. However, we need more than a wormhole. We need a traversable wormhole. A traversable wormhole is exactly what the name implies. We can move through or send information through it.
If you would like to visualize what a wormhole does, imagine having a piece of paper whose two-dimensional surface represents four-dimensional space-time. Imagine folding the paper so that two points on the surface are connected. I understand that this is a highly simplified representation. In reality, we cannot visualize an actual wormhole. It might even exist in more than four dimensions.
How do we create a traversable wormhole? No one knows, but most scientists believe it would require enormous negative energy. This is interesting, since the Existence Equation Conjecture, discussed in previous posts, implies moving in time requires negative energy. A number of scientists believe the creation of negative energy is possible, based on the study of virtual particles and the Casimir effect.
Assuming we learn how to create a traversable wormhole, how would we use it to travel in time? The traversable wormhole theoretically connects two points in space-time, which implies we could use it to travel in time, as well as space. However, according to the theory of general relativity, it would not be possible to go back in time prior to the creation of the traversable wormhole. This is how physicists like Stephen Hawking explain why we do not see visitors from the future. The reason: the traversable wormhole does not exist yet.
Stephen Hawking did a fascinating time-traveler experiment in his popular TV series, “Into the Universe with Stephen Hawking.” He held a reception for time travelers from the future. He sent the invitations out after the reception had already occurred. His hope was that someone in the far-distant future would come across the invitation, and travel back in time to attend the reception. In the TV series, you see the reception room and Stephen Hawking, but no time travelers. He was disappointed.
However, we have four possible explanations why no time travelers attended:
1. The invitation did not survive into the far-distant future, a future whose science enabled time travel to the past.
2. Time travel into the past is not possible in the future, regardless of how far into the future the invitations survive.
3. The human race does not exist in the distant future, destroyed by our own hand, or a cosmic calamity.
4. Time travelers showed up at the party, but it was in another universe (an alternate reality suggested by the “Many-Worlds of Quantum Mechanics” theory). Perhaps in that reality, the TV series broadcasts a reception room filled with time travelers.
Although, we are discussing time travel, it is essential to note that wormholes imply connections between different points in space. This means that they may provide a faster-than-light connection between two planets, for example. Although faster-than-light travel is not possible, the wormhole may represent a shortcut. Travel inside the wormhole may remain below the speed of light, but be faster than the time it would take light to traverse the same two points outside the wormhole. Think of this simple picture.
You are on one side of the mountain. If you want to travel to the other side of the mountain by traversing its circumference, the journey will take longer than using a tunnel that connects to the other side of the mountain. The speed you travel is the same, but the tunnel allows a shortcut, and it appears that you traveled faster.
Will we ever be able to create traversable wormholes? Theoretically, it appears possible. Experiments are being conducted, as I write, using the Large Hadron Collider to create small wormholes, small black holes, and dark matter. The next decade holds considerable promise to address these questions.
Source: Unraveling the Universe’s Mysteries (2013), Louis A. Del Monte
Image: iStockPhoto (licensed)
