Energizer Universe - Still Expanding

 From Abigail Beall of BBC FUTURE...

Let's start by saying the Universe is big. When we look in any direction, the furthest visible regions of the Universe are estimated to be around 46 billion light years away. That's a diameter of 540 sextillion (or 54 followed by 22 zeros) miles. But this is really just our best guess – nobody knows exactly how big the Universe really is.

That is because we can only see as far as light (or more accurately the microwave radiation thrown out from the Big Bang) has travelled since the Universe began. Since the Universe burst into existence an estimated 13.8 billion years ago, it has been expanding outwards ever since. But because we don't know a precise age for the Universe either, it makes it tricky to pin down how far it extends beyond the limits of what we can see.

One property that astronomers have tried to use to help them do this, however, is a number known as the Hubble Constant.

"It's a measure of how fast the universe is expanding at the current time," says Wendy Freedman, an astrophysicist at the University of Chicago who has spent her career measuring it. "The Hubble Constant sets the scale of the Universe, both its size and its age."

It helps to think about the Universe like a balloon being blown up. As the stars and galaxies, like dots on a balloon's surface, move apart from each other more quickly, the greater the distance is between them. From our perspective, what this means is the further away a galaxy is from us, the faster it is receding.  READ MORE

Exploiting Quantum Mechanics

University of Chicago study finds that bacteria know how to exploit quantum mechanics...

Photosynthetic organisms harvest light from the sun to produce the energy they need to survive. A new paper published by University of Chicago researchers reveals their secret: exploiting quantum mechanics.

“Before this study, the scientific community saw quantum signatures generated in biological systems and asked the question: Were these results just a consequence of biology being built from molecules, or did they have a purpose?” said Greg Engel, Professor of Chemistry and senior author on the study. “This is the first time we are seeing biology actively exploiting quantum effects.”

The scientists studied a type of microorganism called green sulfur bacteria. These bacteria need light to survive, but even small amounts of oxygen can damage their delicate photosynthetic equipment. So they must develop ways to minimize the damage when the bacterium does encounter oxygen.

To study this process, researchers tracked the movement of energy through a photosynthetic protein under different conditions—with oxygen around, and without.

They found that the bacterium uses a quantum mechanical effect called vibronic mixing to move energy between two different pathways, depending on whether or not there’s oxygen around. Vibronic mixing involves vibrational and electronic characteristics in molecules coupling to one another. In essence, the vibrations mix so completely with the electronic states that their identities become inseparable. This bacterium uses this phenomenon to guide energy where it needs it to go.

If there’s no oxygen around and the bacterium is safe, the bacterium uses vibronic mixing by matching the energy difference between two electronic states in an assembly of molecules and proteins called the FMO complex, with the energy of the vibration of a bacteriochlorophyll molecule. This encourages the energy to flow through the “normal” pathway toward the photosynthetic reaction center, which is packed full of chlorophyll.

But if there is oxygen around, the organism has evolved to steer the energy through a less direct path where it can be quenched. (Quenching energy is similar to putting a palm on a vibrating guitar string to dissipate energy.) This way, the bacterium loses some energy but saves the entire system.

To achieve this effect, a pair of cysteine residues in the photosynthetic complex acts as a trigger: They each react with the oxygen in the environment by losing a proton, which disrupts the vibronic mixing. This means that energy now preferentially moves through the alternative pathway, where it can be safely quenched. This principle is a bit like blocking two lanes on a superhighway and diverting some traffic to local roads, where there are many more exits.  READ MORE

Magnoncs:

In a first-of-its-kind discovery, researchers in the University of Chicago’s Pritzker School of Molecular Engineering and Argonne National Laboratory announced they can directly control the interactions between two types of quantum particles called microwave photons and magnons. The approach may become a new way to build quantum technology, including electronic devices with new capabilities.

Scientists have high hopes for quantum technology, which has advanced by leaps and bounds over the past decade and could become the basis of powerful new types of computers, ultra-sensitive detectors, and even “hack-proof” communication. But challenges remain in scaling up the technology, which depends on manipulating the smallest particles in order to harness the strange properties of quantum physics.

Two such quantum particles are microwave photons—elementary particles that form the electromagnetic waves that we already use for wireless communications—and magnons. Magnons are the term for a particle-like entity that forms what scientists call ​“spin waves” — wave-like disturbances that can occur in magnetic materials, and can be used to move information.

Getting these two types of particles to talk to each other has emerged in recent years as a promising platform for both classical and quantum information processing. But this interaction had proved impossible to manipulate in real time, until now.

“Before our discovery, controlling the photon-magnon interaction was like shooting an arrow into the air,” said Xufeng Zhang, a scientist in the Center for Nanoscale Materials at Argonne National Laboratory and the corresponding author of the study. ​“One has no control at all over that arrow once in flight.”

The team’s discovery has changed that. ​“Now, it is more like flying a drone, where we can guide and control its flight electronically,” said Zhang.

Through smart engineering, the team employs an electrical signal to periodically alter the magnon vibrational frequency and thereby induce effective magnon-photon interaction. The result is the first-ever microwave-magnonic device that scientists can “tune” to their wishes.

The team’s device can control the strength of the photon-magnon interaction at any point as information is being transferred between photons and magnons. It can even completely turn the interaction on and off. With this tuning capability, scientists can process and manipulate information in ways that far surpass current versions of hybrid magnonic devices.  READ MORE