Science fiction movies and novels are filled with many far-out ideas. They are often used as a springboard for action, rather than to attempt to predict future trends in science and technology. Many of the most popular tropes, like accelerating a spacecraft at incredible speeds without crushing its occupants, are simply impossible to achieve according to the laws and principles of physics. These laws seem to allow for other sci-fi concepts that may seem impossible, such as wormholes and parallel universes. Let's take a look at some sci-fi concepts that might be possible in theory.
Wormholes
In certain gravity conditions, it might be possible to travel through a wormhole. (Image credit: Shutterstock)
It seems like a story-driver, the idea of a "wormhole", a way to travel through space in a way that allows for almost instantaneous travel from distant parts of our universe, sounds like it was invented. The concept, also known as an Einstein-Rosen Bridge, was a seriously theoretical idea long before sci-fi writers had access to it. It is based on Albert Einstein's theory general relativity, which sees gravity as a distortion in space-time due to massive objects. Einstein, in collaboration with Nathan Rosen, theorized that points of very strong gravity such as black holes could be connected to each other in 1935. So the concept of wormholes was born.
Because the forces of a black hole could destroy anyone who came within its reach, the idea of traveling through awormhole was not considered until the 1980s when Carl Sagan, an astrophysicist, decided that he would write a sci-fi story. BBC reports that Sagan encouraged Kip Thorne, a fellow physicist, to devise a way to travel interstellar distances quickly. Thorne devised a way that was theoretically possible, but very unlikely in practice. It allowed humans to travel interstellar distances by crossing a wormhole. It was eventually incorporated into Sagan's novel Contact (Simon and Schuster 1985), which was later made into a movie with Jodie Foster as the lead.
Although it is unlikely that wormholes ever will be the easy and convenient means of transport depicted in movies, scientists now have a viable alternative to Thorne's original idea. If wormholes exist already in the universe, it is possible to locate them using the new generation gravitational-wave detectors.
Warp drive
If you can manipulate the space around your spaceship, it is theoretically possible to travel faster that the speed of light. (Image credit to EDUARD MOZHEVSKYI/SCIENCE PHOTO LUBARY via Getty Images
Space-based adventures require that you can travel faster than today to get to A and B. There are many obstacles to this feat with a traditional spaceship, besides the wormholes. The enormous fuel requirement, the devastating effects of acceleration and the fact the universe has a strict speed limit are just some of the obstacles. This is the speed that light travels at exactly one light-year per annum, which is not very fast in cosmic terms. Proxima Centauri is the second closest star to Earth at 4.2 light years from the sun. The center of the galaxy, however, is 27,000 light years away.
There is a loophole in cosmic speed limits. It doesn't limit the speed at which we can travel through space. Einstein said that space can be altered, so it is possible to manipulate the space surrounding a ship to override the speed limit. Although the speed of light would not be affected, the spaceship would travel faster through the surrounding space.
This is what Star Trek's writers had in mind when they created the idea of a "warp driver" in 1960s. It was a plausible sounding term, but not real physics to them. Miguel Alcubierre, a mathematician, discovered a way to solve Einstein's equations. He did this by contracting space in front and then expanding it to its rear. Although Alcubierre's solution is no less complex than Thorne’s traversable wormhole in its initial stages, scientists are working to improve it.
Time travel
According to general relativity, it is possible to travel back in history. (Image credit: Shutterstock)
One of the most important plot devices in sci-fi is the concept of a "time machine". This allows characters to travel back and alter the course of history, for better or worse. This creates paradoxes. For example, in "Back to the Future," would Doc have made his time machine if Marty hadn't visited him using the same machine? Many people believe that time travel is impossible in the real world. However, the laws of physics prove it can happen.
Einstein's theory general relativity explains how it is possible to travel backwards in time, just like in space warps and wormholes. It treats time and space as part of the "space-time continuum", with the two being inextricably connected. Time can also be distorted, just as space can be distorted by a warp drive or wormhole. Sometimes, it can become so bent that it collapses on itself. This is what scientists call a "closed timelike curve", though it could equally be called a "time machine".
According to David Lewis Anderson (physicist), Frank Tipler published a conceptual design for such an automated time machine in 1974. He also describes the research at the Anderson Institute, a private research laboratory. It is called a Tipler Cylinder and must be at least 60 miles long (97 km) according to Humble. It must also be extremely dense with a mass similar to the sun. The cylinder must rotate fast enough to cause space-time distortion to occur so that time can be folded back. Although it may not be as easy as installing a flux capacitor into a DeLorean it is still possible.
Teleportation
Star Trek The Adventure Exhibition in London, 2002. Teleportation is often used in sci-fi films and shows as a way to get people to new places, but it's a very limited tool. (Image credit Scott Barbour / Staff via Getty Images).
Teleportation is best described as an example of sci-fi teleportation in the Star Trek transporter. It is used to transport personnel between locations. Teleportation is a different form of transport than any other. Instead of the traveler traversing space to reach the destination, teleportation creates a duplicate at the destination. The original is destroyed. According to IBM, teleportation can be seen in these terms and at subatomic particles level rather than humans.
Quantum teleportation is a real-world process. This is a process that copies the exact quantum state of a particle such as a photon to another, which may be hundreds of thousands of miles away. Quantum teleportation damages the quantum state of the initial photon. It does appear as though the photon is magically transported to another place. This trick is based upon what Einstein called "spooky actions at a distance", but it is more commonly known as quantum entanglement. The photon to be "teleported", is brought into contact by one of two entangled photos, and the measurement of the resulting state of the photon is sent to the receiver end. This allows the photon to switch into the same state that the teleported photon.
It's a complicated process even for a single photon, and there's no way it could be scaled up to the kind of instant-transportation system seen in "Star Trek." However, quantum teleportation has important applications in real life, including hack-proof communications, super-fast quantum computing, and other secure communications.
Parallel universes
This artist has created bubble universes in a multiverse. (Image credit: Shutterstock)
All we see is the universe. Our telescopes show us billions upon billions of galaxies that have expanded outwards from the Big Bang. But is this all there is? The theory suggests that there may be many other universes. Although the idea of parallel universes is a familiar theme in sci-fi, they are often only minorly different from our universe when shown on screen. The reality could be even stranger. Parameters like the strength of gravity and nuclear forces may differ from ours in a parallel universe. Isaac Asimov's novel, "The Gods Themselves", is a classic depiction of a truly different universe and the creatures that live in it (Doubleday, 1972).
The concept of "eternal inflation" is key to modern understandings of parallel universes. The infinite fabric of space is in an endless state of rapid, continuous expansion. Each now and again, a small area of this space experiences a Big Bang that stops the general expansion. This allows material objects such as stars and galaxies to form within it. This theory states that the universe is only one of many such regions, although there could be many others.
As Asimov's story suggests, parallel universes may have different physical parameters than ours. Scientists believed that universes with similar parameters to ours could support life. However, recent research suggests otherwise, Live Science reported. There is still hope for Asimov's aliens, but perhaps not for contact with them as in the novel. However, we might still be able to detect other universes through other means. In The Conversation, Ivan Baldry, a professor at Liverpool John Moores University, suggested that the mysterious "cold spots" in the cosmic microwave background could be a result of a collision with another universe.
Original publication on Live Science
