The ALPHA collaboration has conducted the most accurate experiment ever to measure the behavior of neutral antimatter in a gravitational field. Depending on the results, this could open the door to incredible new technologies. Many science fiction technologies will remain in the realm of fiction for a long time (or forever), unless physics changes. But many experiments can check this too?
The dream of instant communication, interstellar spaceships and the ability to travel in time are hackneyed cliches of science fiction. In many ways, they represent humankind's greatest hopes, and yet rely on technology that goes beyond what is currently known. However, new experiments are constantly being carried out and developed. If we're lucky, what can we find beyond the horizon? Ethan Siegel of Medium.com answers the following question:
"Assuming we're lucky, what kind of science experiments over the next few decades could open up science fiction opportunities for us?"
There are some fantastic opportunities that could shake up our reality by the end of the 21st century.
Any rockets ever built require fuel. But if we were to create a dark matter engine, new fuel could be found literally every step of the way through the galaxy.
Dark matter can be an unlimited source of fuel that we don't need to carry around
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One of the biggest mysteries in science is, in fact, the nature of dark matter. We know that it exists through indirect observation, and we know that there is a lot of it. If you add up all the ordinary matter in a large galaxy, it turns out that there is five times more dark matter. And it is almost certainly made up of particles with some common properties:
- they have mass
- they have no electric or colored charge
- they interact gravitationally
- they must, at a certain level, collide with each other and / or with ordinary matter
From Einstein's famous formula E = mc2, we learned that dark matter contains a huge amount of energy: five times more than all ordinary matter combined. If the universe is good to us, we might try to extract it.
The mass distribution of Abell 370, reconstructed using gravitational lensing, shows two large, diffuse mass halos corresponding to the dark matter of the two merging clusters. There is five times more dark matter near and inside any accumulation of ordinary matter.
Many experiments are looking for collisions of dark matter both with ordinary matter and with itself. In general, there are two types of particles: fermions (with half-integer spin) and bosons (with integer spin). If dark matter is a boson, this means that it is most likely its own antiparticle, which means that if you take two dark matter particles and force them to interact with each other, they will mutually annihilate. And if they are destroyed, they will produce pure energy. In other words, it is a free, unlimited source of energy that is available everywhere and in abundance. And you don't even need to take it with you if you decide to cross the Universe. Therefore, when you hear about experiments to search for dark matter, unlimited, free energy is our ultimate, desired goal.
An illustration of a Star Trek warp field that shrinks the space in front of it, lengthening the space behind it
Antimatter can have negative mass, which means it could be the key to a warp drive
If you want to travel to the stars, conventional sources of energy and fuel will only get you from the fence until lunchtime. Or they will move no faster than the speed of light. The closest solar-type star with potentially habitable worlds, Tau Ceti, is about 12 light-years away. That is, the round trip alone will take at least half your life. But if we could shrink the space in front of us as we travel through interstellar space while expanding it behind us, we could get there much faster. This was the idea that astrophysicist Miguel Alcubierra came up with in 1994, who later formalized it according to the canons of strict science.
Only now, to solve Alcubierra, a negative mass is needed
To achieve the correct configuration of space-time required to accelerate the warp drive, two conditions must be met: a colossal amount of energy and the existence of negative mass. This negative mass, which is still known only on paper, is needed for the correct curvature of space-time, and therefore for warp movement. But we have never measured the mass of antimatter particles; they fall "down" or "up" in the gravitational field, this is still unknown. CERN's ALPHA experiment is currently measuring the gravitational effects of antimatter and its behavior in a gravitational field. If the answer is to fall "up" in the gravitational field, we will simply get our negative mass and assemble the warp drive.
The Virtual IronBird tool allows you to create artificial gravity, but requires a lot of energy and allows you to provide only a specific centripetal force. True artificial gravity would require negative mass
Negative mass would also allow us to create artificial gravity
The same possibility - the existence of negative mass in the Universe - would allow us to create an artificial gravitational field. The existence of positive and negative charges in electromagnetism allows us to create conductors, manipulate electric fields, and shield those electric fields. Gravity, as we now understand it, has only one type of charge: positive mass. The existence of negative mass would allow us to create a true environment with zero gravity and would provide us with the ability to create an artificial gravitational field of any magnitude between two systems of positive and negative mass.
The idea of time travel is constantly popping up in science fiction. But if there are closed timelike curves in the universe, this is not only possible, but inevitable.
A rotating universe could allow us to go back in time
At the same time, time travel is not only possible, but also inevitable … in the forward direction. Since space and time are united by the fabric of space-time, it will take a significant shake-up of the physics we know to make time flow in the opposite direction. In space, returning to its original position is quite simple: the Earth itself does this when it revolves around the Sun, but at the same time passes a significant distance forward in time, that is, time passes, about one year. A “closed space-like curve” is easy to make. However, to return to the starting point in time, something unusual will be required: a "closed timelike curve" is a feature that does not exist in our expanding, matter-filled Universe. Unless the universe is spinning.
In the universe that rotates, there is an exact solution in which the density of matter and the cosmological constant (aka dark energy) have certain values, and the universe should have closed time-like curves. Until now, we have only imposed restrictions on the general, global rotation of the Universe, but did not completely exclude it. If the universe rotates at a certain speed, which is balanced by a given density of matter and a cosmological constant, it will be absolutely possible to go back in time and return to the exact place where you started, not only in space, but also in space-time. Large-scale surveys of deep-sky structures, which can provide observations from WFIRST or LSST observatories, could reveal such rotation, if any.
Concept image of NASA's WFIRST satellite, which will go into space in 2024 and will provide us with the most accurate measurements of dark energy, and also make other discoveries
There are always more exotic possibilities than science allows - teleportation of physical objects, instantaneous movement between open locations (wormholes), or communication faster than the speed of light - but this will require much more complex dances with tambourines than a simple experiment with two possible outcomes. However, we keep looking. Science is not a one-way story. It's an ongoing detective story, where every discovery, every data point, and every experiment inevitably leads to deeper questions in the future. It is important to keep an open mind along the way.
Ilya Khel