Quantum physics gets real weird real fast, and one idea gaining more currency of late is the concept of quantum retrocausality, where a decision made in our experience of the present may influence what we experience as the past.

These aren't a bunch of Time Cube type cranks, either. From a helpful overview by Lisa Zyga:

First, to clarify what retrocausality is and isn't: It does not mean that signals can be communicated from the future to the past—such signaling would be forbidden even in a retrocausal theory due to thermodynamic reasons. Instead, retrocausality means that, when an experimenter chooses the measurement setting with which to measure a particle, that decision can influence the properties of that particle (or another particle) in the past, even before the experimenter made their choice. In other words, a decision made in the present can influence something in the past.

Huw Price has done some great introductory lectures like this on the concept:

• WTF is Quantum Retrocausality? (YouTube / Seeker) Read the rest

The more you know about a quantum particle's position, the less you know about its momentum, and vice versa. This is the Heisenberg uncertainty principle, and I thought it applied to quantum particles only, so I didn't mind not understanding why this was so because quantum physics is weird. But 3Blue1Brown says the Heisenberg uncertainty principle applies to non-quantum things to, and in this 20-minute video, he explains why. You can actually get a reasonably good understanding of the uncertainty principle by watching the first two minutes of the video. Read the rest

Chinese researchers demonstrated quantum entanglement at a record distance, between a satellite and ground stations 1,200 kilometers apart. When objects are quantum entangled, their quantum states are linked. Measuring the state of one affects the state of the other. It's weird shit. So weird that Einstein called it "spooky action at a distance."

The experiment by physicists at Shanghai's University of Science and Technology of China could eventually lead to highly-secure communications technologies in space and back on Earth.

"I'm personally convinced that the internet of the future will be based on these quantum principles," says Anton Zeilinger, a physicist at the Austrian Academy of Sciences in Vienna who was not involved in the experiment. "China’s quantum satellite achieves ‘spooky action’ at record distance" (Science)

Read the rest

MinutePhysics responds to CGP Grey's video "The Trouble with Transporters," below.

Read the rest

Nicholas writes, "Since Einstein's day, scientists have been trying to directly observe the wave- and particle- aspects of light at the same time. Now, scientists at a Swiss lab have succeeded in capturing the first-ever snapshot of this dual behavior." Read the rest

Photosynthesis allows plants to convert light from the Sun into energy, and, in some cases, it does this incredibly well. In fact, certain bacteria can capture 95% of the light that hits them and turn it into useful energy.

Solar panels also convert light from the Sun into energy—but they aren't nearly as good at it. The very best solar panels ever tested in a lab (i.e., not the ones actually available for sale and installation on your house) were able to convert about 34% of the light that hit them into electricity. (Individual experimental solar cells can do better than that. But those are even further away from being incorporated into commercially available panels.)

Why can't we use the Sun's energy as effectively as bacteria can? The secret may be that the bacteria are using quantum physics to transmit energy. It's sort of like the bacteria have a method for keeping boxes of energy from falling off the truck during transport. Read the rest

Ian McDonald has spent the past two decades blowing the lid off of science fiction with his poetic, dense, lavish novels that span the universe from Mars to Africa, from the future to the past, from Brazil to India to Turkey. Now McDonald has begun a second career as a young adult novelist with his Everness series, the first volume of which is Planesrunner, which goes on sale today.

Planesrunner is the story of Everett Singh, a moderately unhappy schoolboy in London whose divorced, quantum physicist dad is kidnapped before his eyes one night. Everett embarks on an epic quest to find out what happened to his dad, a quest that is complicated by his mother's hostility to her ex-husband, a police cover-up, sinister visits from the head of the Imperial College physics department, and mysterious, threatening strangers who tail him through the streets of London.

But Everett is convinced that he saw what he saw, and that his father is in peril -- not least because his Dad's server has emailed him a firmware update for his tablet that turns it into an n-dimensional directory of the multiverse, an insurance file on a dead man's switch that was sent to Everett when his dad was offline for a critical amount of time. Everett can't outwit the forces of evil forever -- but he can choose the way he is captured, and he does, and that's how he manages to escape through an interdimensional portal and penetrate a parallel electricpunk universe where there is no oil, but where coal-fired manufactories turn out the carbon nanofiber necessary to support a global industry of freewheeling electrified airships. Read the rest

GOD-MAN commands that you visit the TOM THE DANCING BUG WEBSITE often (at least once a week, unless you have a REALLY good reason, like your football team's in the playoffs); and if you don't follow RUBEN BOLLING on TWITTER, there's no way God-Man's answering your call when you signal him on the special GOD-MAN RADIO WRISTWATCH you received when you joined his Fan Club. (YOU DID JOIN HIS FAN CLUB, DIDN'T YOU?) Read the rest

A couple of years ago our friend Clifford Pickover wrote the terrifically fun book, The Math Book. Now he's got a new one that's just as good about physics. It's called, as you might guess, The Physics Book and the publisher has kindly given me permission to run some examples from the book. You can check all of them out after the jump.

2 Billion B.C.: Prehistoric Nuclear Reactor -- Francis Perrin (1901-1992)

"Creating a nuclear reaction is not simple," write technologists at the U.S. Department of Energy. "In power plants, it involves splitting uranium atoms, and that process releases energy as heat and neutrons that go on to cause other atoms to split. This splitting process is called nuclear fission. In a power plant, sustaining the process of splitting atoms requires the involvement of many scientists and technicians."

In fact, it was not until the late 1930s that physicists Enrico Fermi and Leo Szilard fully appreciated that uranium would be the element capable of sustaining a chain reaction. Szilard and Fermi conducted experiments at Columbia University and discovered significant Neutron (subatomic particle) production with uranium, proving that the chain reaction was possible and enabling nuclear weapons. Szilard wrote on the night of the discovery, "there was very little doubt in my mind that the world was headed for grief."

Because of the complexity of the process, the world was stunned in 1972 when French physicist Francis Perrin discovered that nature had created the world's first nuclear reactor two billion years before humankind, beneath Oklo in Gabon, Africa. Read the rest