Tag: physics

Universal Scaling

And this scrambling process happens very early indeed. In their papers this spring, Berges, Gasenzer and their collaborators independently described prescaling for the first time, a period before universal scaling that their papers predicted for nuclear collisions and ultracold atoms, respectively. Prescaling suggests that when a system first evolves from its initial, far-from-equilibrium condition, scaling exponents don’t yet perfectly describe it. The system retains some of its previous structure — remnants of its initial configuration. But as prescaling progresses, the system assumes a more universal form in space and time, essentially obscuring irrelevant information about its own past. If this idea is borne out by future experiments, prescaling may be the nocking of time’s arrow onto the bowstring.

Quantum Darwinism

One of the most remarkable ideas in this theoretical framework is that the definite properties of objects that we associate with classical physics are selected from a menu of quantum possibilities in a process loosely analogous to natural selection in evolution: The properties that survive are in some sense the “fittest.” As in natural selection, the survivors are those that make the most copies of themselves. This means that many independent observers can make measurements of a quantum system and agree on the outcome — a hallmark of classical behavior.

Quantum amplification

Their method achieves 50 times more precision than the previous best techniques, which also means that they can make measurements 50 times faster than before. Now they can narrow down the particle’s location to an atom-sized space in less than a second. The key to their method is to accept the noisiness decreed by the uncertainty principle, and control where it manifests itself. To measure the ion’s position, they basically transfer the uncertainty into its speed, a value they happen to care less about.

Continuous Quantum Leaps

By making a kind of high-speed movie of a quantum leap, the work reveals that the process is as gradual as the melting of a snowman in the sun. “If we can measure a quantum jump fast and efficiently enough, it is actually a continuous process.” But there’s more. With their high-speed monitoring system, the researchers could spot when a quantum jump was about to appear, “catch” it halfway through, and reverse it, sending the system back to the state in which it started. What seemed to be unavoidable randomness in the physical world is now shown to be amenable to control. We can take charge of the quantum.

Dark Matter Evidence?

While dark matter doesn’t shine or fraternize with known particles, in the right sort of collision these particles could annihilate in a shower of familiar matter and antimatter that would then go out with a puff of gamma rays. A measurement of these offshoots would represent the first evidence of dark matter that wasn’t exclusively gravitational in nature. Yet dark matter wasn’t the only thing that could be generating the excess gamma rays. They could shine from cosmic lighthouses known as millisecond pulsars — magnetically charged neutron stars that make 1000 turns each second. A group of undiscovered pulsars too dim to be picked out individually could be bathing the center of the galaxy in extra gamma rays. Experts express optimism that with these inputs, the current modeling wars could settle down in a matter of years. And now that the gamma ray glow is back on the table, hopes for dark matter look somewhat brighter. “If the galactic center excess is back in the game, potentially we are seeing the first signal of dark matter.”

Strange Stars & Matter

Nuclear physicists hypothesize that when the cores of neutron stars are subject to enough pressure, the quarks that make up the core can turn from up and down quark varieties into strange quarks. As this Kurzgesagt video explains, this strange matter is particularly stable and if it were to escape from the core of the neutron star, it would convert any ordinary matter it came into contact with to more strange matter

Consensus Reality

Physicists have long suspected that quantum mechanics allows 2 observers to experience different, conflicting realities. Now they’ve performed the first experiment that proves it. They use 6 entangled photons to create 2 alternate realities—1 representing Wigner and 1 representing Wigner’s friend. Wigner’s friend measures the polarization of a photon and stores the result. Wigner then performs an interference measurement to determine if the measurement and the photon are in a superposition. The experiment produces an unambiguous result. It turns out that both realities can coexist even though they produce irreconcilable outcomes, just as Wigner predicted. That raises some fascinating questions that are forcing physicists to reconsider the nature of reality.