The idea of spaceships zipping across the universe at superluminal speeds is a staple of science fiction. But physicists are still trying to figure out how to achieve such travel.
One of the biggest obstacles to faster-than-light travel is Albert Einstein’s special theory of relativity, which states that speed is relative and that time dilation occurs as you approach light speed.
1. Warp Drives
For decades, science fiction fans have dreamed of traveling at warp speed. In fact, Star Trek has a long history of featuring fast interstellar travel, with Captain Kirk and his crew using high-powered tractor beams to get their ships from point A to point B as quickly as possible.
The problem is that physicists haven’t been able to make this happen, largely because of the energy requirements needed. While this sounds like an impossible task, it is actually something we’re closer to than you think.
This is thanks to a concept called warp drive, which is what enables Star Trek’s intrepid ships to travel at near-light speed. In general, warp drives work by bending spacetime to enable a ship to zip between stars. This is because gravity bends spacetime around hefty objects, such as stars and black holes, causing them to compress in front of the spaceship while expanding behind it.
In order to do this, warp drives need to create a subspace bubble that wraps around the entire ship. This creates a sort of “warp field” that lowers the inertial mass of the ship and accelerates it, too.
However, there’s a lot that goes into making warp drives work, from exotic matter to energy requirements and more. While all of these concepts can seem impossible, scientists have found ways to tweak them so that they’re more feasible.
One of these solutions is a geometric approach that reduces the amount of exotic matter that needs to be used to create the warp drive. This is especially useful in cases where you’re not interested in going anywhere near the speed of light, but want to get from point A to point B.
Another solution, which is more of an engineering problem, is to change the way that spacetime within a warp drive bubble is modified. Scientists Alexey Bobrick and Gianni Martire recently discovered that this change would reduce the amount of exotic matter required to create a warp drive and eliminate the need for negative energy.
While these changes might not be enough to create a true warp drive, they’re certainly an improvement over the original idea that was proposed by Miguel Alcubierre in 1994. These modifications may be the key to moving faster-than-light travel out of science fiction and into the realm of a practical, real-world reality.
Scientists have long bandied about the possibility of wormholes, which could help people travel through space in seconds. Essentially, a wormhole would be a tunnel that connects two points in spacetime and allows people to move between them without being limited by time and the speed of light.
Wormholes are also supposed to be able to help people travel back in time. However, this is only possible if one of the ends was accelerated to nearly the speed of light. This could cause the wormhole to become distorted and it wouldn’t be possible for people to see the same view of their destination that they saw when they entered the wormhole.
Physicists have been searching for ways to create and stabilize wormholes, which would make it possible to travel faster than light. To do this, scientists would need exotic matter that has negative mass.
The most important part of this is that it would have to be able to counteract the pull of gravity. This is because if gravity was too strong, the entire wormhole would collapse and no one could enter it. Thankfully, scientists believe that there is a way to stabilize a wormhole — by using negative energy.
This energy would be able to oppose gravity, keeping the wormhole stable and allowing travelers to travel at superluminal speeds. The only problem with this is that the negative energy must be stable in order for it to keep working properly.
If it was unstable, then a wormhole could collapse at any point in time. This would cause it to lag behind the other end, which wouldn’t allow someone to travel back in time.
In addition to this, there are other reasons wormholes are not viable for use as time machines. This is because the time taken to travel through a wormhole is based on Einstein’s theory of general relativity. Special relativity dictates that moving clocks are slower than still ones. So if you traveled through a wormhole, you’d be traveling through your own past.
Even though wormholes are a bit hard to create, it’s important to note that they’re the only type of superluminal travel that is currently possible. This means that if they did exist, they’d be vital for interstellar civilizations.
Particle accelerators are a kind of equipment that propels particles, like protons or electrons, near the speed of light. This is done by creating an accelerating electric field between positive and negative potentials (the same as the voltages in a battery).
Accelerators are found in a wide range of sizes, from the cathode ray tube in your television to huge circular devices, such as the Large Hadron Collider at CERN. But all share the same basic elements, including a source of electrically charged particles (electrons or protons), a high-voltage electrode at the center, and an accelerating electric field.
The simplest accelerators have one end of the device with a particle source, and the other end is separated by an insulated, vacuum tube that creates a uniform static electric field between the two ends. The electrons or protons in the plasma are attracted to this field. The resulting acceleration produces a strong force that accelerates the particles, and they move rapidly toward the other side of the tube.
This accelerated energy is transferred to the particles through electromagnetic forces, which focus them into a beam that can then be transmitted or used to propel the particles farther away from their source. In this way, the particles travel through a vacuum chamber that contains as little air as possible, and they can be sent out in a variety of directions.
There are three main types of accelerators, each requiring its own set of parts. The smallest are called linacs, which consist of an insulated, evacuated tube with a high voltage between the ends. The Stanford Linear Accelerator, at SLAC National Accelerator Laboratory, is 2 mi (3.3 km) long and can accelerate particles to 50 gigaelectronvolts (GeV).
Another type of accelerator consists of a circular tube with magnetic fields and radio-frequency electric fields that create an alternating voltage between pairs of D-shaped magnets. This form of acceleration can be synchronized so that the particles take exactly one revolution in each pass through the tube.
The most complex types of accelerators, known as colliders, are designed to make beams of particles smash into each other at a chosen point. They are more demanding to construct, but their collisions are powerful, with a large gain in energy of interaction. They are the workhorses of many areas of science, including particle and nuclear physics.
4. Nuclear Fusion
In nuclear fusion, two particles are heated to extreme temperatures that make them collide with enough energy to overcome their repulsive electrostatic forces. This allows the strong nuclear forces that pull protons and neutrons together to fuse them into one atom.
The simplest form of fusion is the fusing of hydrogen nuclei into helium. This is an exciting and important energy-producing process that could help solve the global climate crisis.
For the fusion reaction to work, the nuclei must be heated to ten million degrees Celsius (about 18,000,032 degrees Fahrenheit) so that they can collide with enough energy to overcome their repulsive charges. Hydrogen has the smallest charge and therefore fuses at the lowest temperature. This is why it’s commonly used as a fuel source for nuclear power plants.
Other nuclei have much larger charges, making them more difficult to fuse. Deuterium and tritium atoms are isotopes of hydrogen that have a smaller total charge and thus are more energetically favorable for fusion.
These smaller nuclei can be controlled by the magnetic fields of a device called a tokamak. The tokamak’s magnets attract and bind the nuclei, causing them to heat up and fuse together.
Then the hot fusion plasma releases energy in the form of heat and light. When we think of the Sun, which powers our planet and other stars in space, this energy travels outward as radiation. This radiation is bouncing off the plasma and traveling at the speed of light, but because the solar plasma is so dense it takes an average of a million years for this energy to reach Earth.
There are other methods of controlled fusion, including using lasers to fire particle beams at a target. These beams are called neutron sources, and they are essentially portable accelerators that shoot particle beams of deuterium or tritium ions at a target to make it undergo fusion.
In a world where over-reliance on fossil fuels is putting our planet at risk, scientists hope that nuclear fusion will become an important renewable energy source. It consumes vast amounts of energy, but by making the process self-sustaining researchers believe they can reduce their reliance on fossil fuels while producing carbon-free electricity. The process is still in its early stages, but many experts predict it will be an important energy source for the future.