All posts tagged: quantum physics

We have figured out a new way to send messages into the past

We have figured out a new way to send messages into the past

Published by skeptic

Closed time-like curves offer a route to the past Roman Budnikov/Alamy What if you could send a message into the past? The laws of physics don’t forbid it – and in fact, in some cases, communicating backwards in time might actually be easier than the usual direction. The possibility of sending a message to the past emerges from a particular kind of solution to the equations of general relativity, which is our best theory of how space-time, the fabric of reality, behaves. Every object in the universe follows a path through space-time, and one such path that is allowed by general relativity is called a closed time-like curve (CTC), which sees an object travel into the future before returning to the past and ending up in the present, forming a time loop. There is just one catch: at cosmic scales, building a CTC would mean bending space-time until it closes in on itself, which would require an impossibly large amount of energy. That seems to rule out sending a message back in time – but …

Is consciousness more fundamental to reality than quantum physics?

Is consciousness more fundamental to reality than quantum physics?

Published by skeptic

Imagine you could take a cosmic mixing bowl and cook up reality from scratch. It would be a strange kind of baking, with the end results including everything from space-time and satellites to cats and the cosmic web. But here’s the question: what would be the basic ingredient you’d need to use? I first got introduced to this kind of question in seventh grade, sitting in a class I had never taken before: physics. Although this introductory class was mostly about balls rolling down hills, I was taught that the methods of physics ought to have limitless reach – an idea called reductionism. Physics should be able to identify the essential ingredients of reality and show how to combine them from scratch into anything and everything. Immediately, I decided to become a physicist. But now, many years and several degrees later, I am less sure that physics holds all the answers. Take something like my sense of self: is that really a consequence of some equation that we haven’t yet derived? If I think about …

The strange connection between falling balls and quantum weirdness

The strange connection between falling balls and quantum weirdness

Published by Jenni Sidey

A ball tossed into the air follows a path that classical physics can track with confidence. Shrink that ball down to the size of an atom, though, and the rules usually change. At that scale, particles can seem to pass through two openings at once. They can also tunnel through barriers and act more like waves than tiny objects. Now two MIT researchers say there is a tighter mathematical connection between those two worlds than physicists once thought. In a new paper, the team reports that a familiar idea from classical physics, known as least action, can be extended to reproduce the same answers as the Schrödinger equation for several standard quantum cases. Their method, they say, can handle examples such as the double-slit experiment and quantum tunneling. It does so while relying on a framework built from classical action and density. “Before, there was a very tenuous bridge that worked only for reasonably large [quantum] particles,” says study co-author Winfried Lohmiller, a research associate in the Nonlinear Systems Laboratory at MIT. “Now we have …

Quantum researchers created a new kind of laser built from sound

Quantum researchers created a new kind of laser built from sound

Published by Jenni Sidey

A tiny silica bead, just 100 nanometers across, sits suspended in a vacuum and vibrates under the grip of laser light. Those vibrations might sound like a small detail, but in this case they are the heart of a new kind of laser, one that works not with light particles, but with particles of mechanical motion. Researchers at the University of Rochester and Rochester Institute of Technology have built what they describe as a squeezed phonon laser, a system that gives unusually tight control over phonons, the quantum units of vibration or sound. Their results, reported in Nature Communications, push phonon lasers into new territory by combining laser-like coherence with reduced noise in a levitated nanoparticle system. That matters because noise is a constant problem in precision measurement. Even ordinary lasers, which look steady to the eye, are never perfectly calm. Their output fluctuates, and those fluctuations can blur a signal. The same basic problem affects phonon lasers. “While a laser looks to the naked eye like a steady beam, there’s actually a lot of …

Universe may have 7 dimensions in bombshell theory | Science | News

Universe may have 7 dimensions in bombshell theory | Science | News

Published by Sam Flores

A paradox that stumped scientists for decades has an explanation, as long as the universe has seven dimensions. Stephen Hawking’s theory that black holes eventually evaporate into nothingness presented a contradiction to a fundamental understanding in physics and quantum mechanics. However, a new theory by scientists suggests that black holes never fully disappear and remnants are left behind, as long as there are seven dimensions, three extra to the traditionally accepted four dimensions we have known about for generations. Scientists believe that, as well as length, width, height and time, there are three hidden dimensions in the universe, and they are folded so densely that they cannot be easily perceived. This seems to solve the decades-old ‘information paradox’, as traditionally, the laws of quantum mechanics state that information can never completely disappear or be destroyed, which contradicts Hawking’s theory that back holes eventually evaporate and cease to exist. Senior researcher at the Slovak Academy of Sciences, Richard Pinčák, told the Daily Mail: “Imagine you throw a book into a fire. The book is destroyed, but …

Quantum batteries could be charged by reversing time

Quantum batteries could be charged by reversing time

Published by skeptic

Quantum batteries could harvest energy by reversing time’s arrow da-kuk/Getty Images A method that can reverse the flow of time in quantum systems could one day be used to help charge quantum batteries. For every process we observe in the universe, events appear to happen in only one direction, following an apparent arrow of time. But most physical laws and equations work whether time flows forwards or backwards. Physicists have different explanations for why a discrepancy exists between the observed forward arrow of time and the permitted two-way flow. For example, the second law of thermodynamics says that systems are more likely to become disordered as time goes on, creating a preferred direction of time. In the quantum world, the arrow of time is defined differently. Quantum processes, like classical physical laws, can run in either direction, but we can define an arrow of time by comparing our measurements of a quantum system with our calculations of how a quantum system should change over time. When these line up with a particular statistical pattern, we …

We might finally know the size of the proton

We might finally know the size of the proton

Published by skeptic

A vacuum chamber used to measure electron transitions in atomic hydrogen, from which the proton’s size was inferred Axel Beyer/MPQ At long last, we have pinned down the size of a proton. More than 15 years after an experiment unexpectedly shook the world of particle physics, researchers are regaining their grip on one of this fundamental particle’s most basic properties. Look around you, and everything you see will be filled with protons. The proton is a fundamental building block of our world – and until 2010, we thought we understood it fairly well. We knew its composition – it is made from three quarks – and we knew its size. Then, a measurement based on an exotic hydrogen atom showed that the proton may actually be about 4 per cent smaller than expected. Physicists scrambled, exploring sources of experimental error as well as theories about new physics phenomena that could resolve this “proton radius puzzle”. In 2019, another experiment strengthened the evidence that the proton’s size had long been overestimated. Now, the issue may have …

Quantum entanglement can be measured in solids for the first time

Quantum entanglement can be measured in solids for the first time

Published by skeptic

The behaviour of two distinct particles can be linked by quantum entanglement Science Photo Library / Alamy We finally have a way to measure quantum entanglement of solids, which could lead to advances in both quantum technology and fundamental physics. When it comes to quantum entanglement – an inextricable link between quantum particles that keeps their behaviours correlated, even when they are extremely far apart – researchers have limited experimental tools. They can determine if two particles are entangled by using a procedure called the Bell test, for example, and purposely create entanglement between several objects within quantum computers. But finding out whether a piece of some material is full of entangled particles is more challenging. This is especially important for developing new and better devices for quantum computing and quantum communication, which require entanglement. Allen Scheie at Los Alamos National Laboratory in New Mexico and his colleagues have spent more than half a decade developing a technique to do just that – and now it works. “We’ve established that it works, 100 per cent, …

How a century-long argument over light’s true nature came to an end

How a century-long argument over light’s true nature came to an end

Published by skeptic

Light is both a wave and a particle, and we know it for sure now Anna Bliokh/Getty Images The following is an extract from our Lost in Space-Time newsletter. Each month, we dive into fascinating ideas from around the universe. You can sign up for Lost in Space-Time here. When physicist Clinton Davisson received the Nobel prize in 1937 for discovering that electrons, which had been considered to be particles, could sometimes unexpectedly behave like waves, he made a point of taking a jab at light. He said, “the perfect child of physics [had] been changed into a gnome with two heads”. It was already known to not be one or the other, but both wave-like and particle-like. Physicists used to think that being a particle and being a wave was mutually exclusive, yet here we had, in light and now also electrons, two examples contradicting that. Somewhat baffled, Davisson couldn’t help but reach for a grotesque metaphor. He was in good company – 10 years earlier, Albert Einstein had a famous argument with Niels Bohr over this seeming absurdity. …

We’re solving the fundamental mystery of how reality is glued together

We’re solving the fundamental mystery of how reality is glued together

Published by skeptic

As you read this, every atom in your body is desperately trying to tear itself apart. In fact, that goes for every atom, everywhere, since the beginning of time. Thankfully, those efforts have failed. These self-destructive tendencies relate to the nucleus, a tiny knot of matter at the centre of every atom. Inside, protons are packed shoulder to shoulder, each one bristling with positive charge and frantic to get away from its companions. If atoms obeyed only electricity and magnetism, the universe would have been a brief, bright firework. Instead, something else intervenes, a force so strong it makes electromagnetism look feeble. This maintains the solid furniture of reality by keeping the building blocks of atoms glued together. But the deeper physicists have probed this force, the stranger it has seemed. The equations that describe it look disarmingly simple, yet follow them through and something puzzling happens: a theory built from weightless ingredients somehow produces particles that are unmistakably heavy. Sweeping away this inconsistency wouldn’t just tidy up our understanding of the force that binds …