It may seem strange to think something can survive even the death of the Universe, but that could actually be possible as a result of the laws of quantum physics.
Scientists are now suggesting a new blueprint for a device, known as a time crystal, that can theoretically continue to function as a computer even after the universe cools to absolute zero.
Ordinary crystals are three-dimensional objects whose atoms are arranged in regular, repeating patterns similar to table salt. They adopt this structure because it uses the lowest amount of energy possible to maintain.
MIT physicist Frank Wilczek says: “First you need an ion trap, a device which holds charged particles in place using an electric field…Next, you apply a weak static magnetic field, which causes the ions to rotate.Quantum mechanics means that the rotational energy of the ions must be greater than zero, even when the ring is cooled to its lowest energy state.”Normally, this behavior would violate thermodynamic laws but superconductors allow electrons to rotate continuously.” As the Universe accelerates, it cools, eventually dissipating all its energy until everything is cold, dark, and as far as life is concerned, dead.
But if crystals, such as table salt, could be translated into the fourth dimension of time.
Wilczek theorizes that a working time crystal could be made into a computer, with different rotational states standing in for the 0s and 1s of a conventional computer.
“To make it interesting you want to have different kinds of ions, maybe several rings that affect each other,” he says.
“You can start to think about machines that run on this principle.”
Image credit: crystalsbuy.com
Crucially, they would also have to be in their lowest possible energy state as they do so, meaning that they would naturally continue to rotate even after the universe has succumbed to entropy and cooled to a uniform temperature – a state known as heat-death.
While such behavior would normally violate the laws of thermodynamics, nonstop rotation is allowed in the case of electrons in a superconductor, which flow without resistance.
Wilczek had originally suggested that a superconductive ring could serve as a time crystal if electrons could be made to flow separately rather than in a continuous stream, ensuring a repeating pattern, but he couldn’t figure out how to do so in practice.
Now Tongcang Li at the University of California, Berkeley, and colleagues at the University of Michigan in Ann Arbor and Tsinghua University in Beijing, China, have an alternative suggestion that may be possible to construct.
First you need an ion trap, a device which holds charged particles in place using an electric field.
This causes the ions to form a ring-shaped crystal, as ions trapped at extremely low temperatures repel each.
Next, you apply a weak static magnetic field, which causes the ions to rotate.
Quantum mechanics means that the rotational energy of the ions must be greater than zero, even when the ring is cooled to its lowest energy state.
In this state, the electric and magnetic fields are no longer needed to maintain the shape of the crystal and the spin of its constituent ions. The result is a time crystal – or indeed a space-time crystal, because the ion ring repeats in both space and time.
“I’m very pleased with it,” New Scientists quoted Wilczek as saying.
“They’ve really come up with something that looks like a realizable experimental design,” he added.
We should not expect to see a time crystal computer any time soon, however.
While Wilczek points out that the heat-death of the universe is, in principle, “very user friendly” for this kind of experiment because it would be cold and dark, there are other issues to consider.
“We focus on a space-time crystal that can be created in a laboratory,” says Li. “So you need to figure out a method to make a laboratory that can survive in the heat-death of the universe.”
Yes, one has to admit the idea something can outlive the Universe is fascinating indeed!