Astronomers discover a black hole orbiting a ‘spinning’ star for the first time Read more at http://www.iflscience.com/space/astronomers-discover-black-hole-orbiting-%E2%80%98spinning%E2%80%99-star-first-time#VVfdLAuCdz45pV5p.99

Binary systems are quite common, but astronomers have just discovered one system that was previously only hypothesized: a black hole orbiting a spinning star, known as a Be star. The research was led by Jorge Casares of Astrofísica de Canarias and was published in Nature.

Black holes were first theorized in the late 18th century and were initially termed “dark stars.” Dark stars were believed to have gravity fields so strong, light was not able to escape. There are believed to be three types of black holes: miniature, supermassive, and stellar. While miniature black holes remain theoretical, supermassive black holes are likely found at the center of all galaxies with a mass millions (potentially billions) times higher than our sun. Stellar black holes are formed by the collapse of an extremely massive star and have a mass 3-100 times our sun. The first definitive proof that stellar black holes exist was provided by Casares in 1992.

There are over 80 known Be stars in our galaxy alone. They are in binary pairs, typically with a high-density neutron star. Their name denotes their spectral wavelength in the B-class, while the lowercase e is added to indicate that it has distinct emissions, whose energy transitions do not act in a way that would be expected according to the main tenets of quantum mechanics. Because Be stars spin incredibly fast, they eject a great deal of material and can form a disk around the central star. 

Casares’ team made the discovery while using the Liverpool and Marcator telescopes on the Canary Islands in Spain. They have been studying the star MWC 656 since 2010. It is located 8,500 light years away in the constellation Lacerta. The team knew it was in a binary pair with another object, but the identity of the object was not immediately clear. It was believed to have a mass up to 6.9 times the sun, making it much too massive to be a neutron star. There was also a lack of radiation that was being picked up by the telescopes, which indicated to the team that it had to be a stellar black hole. 

The black hole is likely consuming the matter kicked out by the Be star, which was determined to be spinning at over 1 million kilometers per hour (621,000 mph). The team also found that it is the black hole that is orbiting the Be star, as the star is more massive at approximately 10 solar masses.

Because there are a seemingly endless amount of stars in the sky, astronomical events that have never before been seen are never believed to be the only occurrence; it is just a matter of locating another one. Future research will seek to find other binary systems like this and will attempt to determine how they were formed.

A 1.8 million year old skull indicates there may have been just one human species on Earth at that time

A new paper published in Science details a 1.8 million year old skull. The skull find has stirred up debate amongst palaeoanthropologists, as the authors of the new paper have asserted that the hominid skull shows that Homo habilis, Homo rudolfensis and Homo erectus are all part of a single evolving lineage that led to modern humans. Other scientists disagree however, saying there is still evidence that at least three distinct species of humans co-existed in Africa.

The new cranium, discovered in Dmanisi, (D4500), together with its mandible (D2600), represents the world’s first completely preserved hominid skull from the early Pleistocene. The cranium has a small brain case at 546 cubic centimetres and has a large prognathic face, meaning that its jaws project beyond the upper part of its face. It seems to have close structural similarities (morphological affinities) with the earliest known Homo fossils found in Africa.

The Dmanisi sample is now composed of five crania, and shows direct evidence for wide variation within the early Homo populations - but crucially, within the same species. This variation within the Homo populations is similar to that seen within modern Pan (chimpanzee) groups.

The authors conclude that the diversity seen in the African fossil record around 1.8 million years ago most likely reflects variation between groups of a single evolving lineage rather than species diversity. That single lineage is Homo erectus, with specimens previously attributed to H. ergaster reclassified as a chronosubspecies, H. erectus ergaster. As the Dmanisi population most likely originated from an Early Pleistocene (2.58 – 0.78 million years ago) expansion of the H. erectus lineage from Africa, the authors place it within H. e. ergaster and formally designate it as H. e. e. georgicus, referring to the samples’ geographic location. H. habilis and H. rudolfensis fossils require further testing to determine whether they too belong to a single evolving Homo lineage. Identifying the hominid groups and identifying variation within the populations will aid in understanding the evolution and dispersal of early Homo.

Not all palaeoanthroplogists agree with the authors of this new paper. A previous paper sought to confirm taxonomic diversity in early Homo. The Nature paper showed that three newly discovered fossils, aged between 1.78 and 1.95 million years (Myr) old, showed that there were two contemporary species of early Homo, in addition to Homo erectus, in the early Pleistocene of eastern Africa. This finding added further support to the classification of a skull found in 1972 as a separate species of human, Homo rudolfensis. The skull was the only example of this species which contributes to the contention over its lineage.

A co-author of the Nature study, Fred Spoor, told BBC News that Lordkipanidze et al.’s analysis of the cranium describing the shape of the face and braincase was in broad and sweeping terms, and that those Homo sapiens are not defined using such a broad overview.  Very specific characteristics had been used to define H. erectus, H. habilis and H. rudolfensis, and these were not were not indicated by the landmarks that the team used.

It is clear from this recent finding and previous work that the Dmanisi site still has much more to offer in discoveries of our lineage.

Astronomers Discover The Oldest Known Star In The Universe

A few hundred thousand years after the Big Bang, hydrogen gas started to heat up and the first stars were formed. One of these first stars, which formed around 13.7 billion years ago, has been discovered for the first time. The discovery was made by lead researcher Stefan Keller of The Australian National University and the results were published in Nature.

Dr. Keller’s team is one that operates the SkyMapper telescope at the Siding Spring Observatory in New South Wales. Because elements heavier than helium are forged in the cores of stars, the first ones were made mostly out of hydrogen. The telescope is able to find these first stars because the low iron content influences their color. Using this technique to find early stars, the SkyMapper is currently in a 5-year-long survey, mapping the ancient Southern sky.

The team made the discovery of a lifetime when they discovered the chemical signature from a 13.7 billion year old star; one of the first ever. This star formed so early in our Universe’s history, was most likely a second-generation star. Because of the chemical composition, astronomers can gather information about the earlier primordial star, which is believed to be 60 times more massive than our sun and composed of hydrogen and helium.

The stars we are most familiar with today have different stages in their life cycle. For massive stars (those which are over nine solar masses) heavy elements are fused in the core of the star, up until it hits iron. The nuclei are so tightly bound that it actually consumes energy, instead of producing it like other elements. As more and more iron is created, the star’s core becomes so massive that it eventually collapses, signifying the death of the star. The supernova explosion is violent and all of the elements are ejected out where they will eventually form new stars or planetary bodies. 

It had long been assumed that the first stars exploded in similar ways, but the team found that this wasn’t the case. The explosion from the primordial star’s death was relatively low-energy. While the lighter elements were ejected and would go into new stars, the heavier elements, like the iron, were consumed by the black hole that formed after the supernova. The newly-discovered second-generation star did not have the iron that astronomers believed they would have.

The discovery of this ancient star has given astronomers a deeper insight about the origins of stars and how certain elements began to spread around the early Universe. These low-energy supernovae were likely very common among the first stars and future research will determine when they began to gather more energy and become the explosive events we know them to be today. 

Free-flowing water discovered on the equator of Mars

Before it lost its atmosphere Mars was covered with liquid water. There is now evidence that certain areas of the red planet may still have free flowing water during certain times of the year. The results come from Alfred McEwen of the University of Arizona and were published in Nature Geosciences. 

In 2011, NASA’s Mars Reconnaissance Orbiter (MRO) provided images that showed dark streaks in the soil in areas near the equator. Though they faded over time, the streaks return at the warmest part of each year. The most likely answer is that there could very well be liquid water flowing on the surface of Mars under certain circumstances; an unprecedented discovery, since the atmosphere is much too thin to retain liquid water for long periods of time.

The trouble is, researchers don’t know enough about Martian geology and composition to definitively say where the water could be coming from. There could be pockets of ice underneath the surface that liquify when warmed, but the emergence pattern of the dark streaks doesn’t seem to suggest that. There is also a possibility that the streaks are caused by water vapor being pulled from the atmosphere and condensed into the soil.

For life as we know it to exist, liquid water is a must. The fact that there is still liquid water on the surface of Mars is very exciting, but space agencies need to proceed carefully. Any probes that visit these potentially watery areas must be completely sterilized which is a complicated and expensive procedure. If there were any traces of Earth microbes on the probe, it could easily contaminate that which it was sent to study. The Committee on Space Research (COSPAR) is part of an international organization that defines good research practices in space and would shut down any mission that did not ensure the utmost of cleanliness for the spacecraft.

Of course, completely eliminating microbes is incredibly expensive. To completely prevent contamination, the probe would need to be heated using hydrogen peroxide vapor or ionized radiation to kill anything that might be stuck on the space craft. Similar treatments were performed on Voyager 1 & 2 and were about 10% of the entire budget that has spanned over 35 years. For a probe that would be able to land on Mars and analyze potential liquid water samples, the sterilization price tag could be too great to overcome for any one agency. Eventually, though, the mission will be done correctly, and having accurate and meaningful data will be well worth the investment.

New State of Matter Discovered

Photo credit: Image of the probability of location of an electron hole in the newly discovered dropletons. The electron is located at the centre of the peak, and the heights indicate the probability of hole location. Credit: The Cundiff Group and Brad Baxley, JILA

There was a time when states of matter were simple: Solid, liquid, gas. Then came plasma, Bose -Einstein condensate, supercritical fluid and more. Now the list has grown by one more, with the unexpected discovery of a new state dubbed “dropletons” that bear some resemblance to liquids but occur under very different circumstances.

 

The discovery occurred when a team at the University of Colorado Joint Institute for Lab Astrophysics were focusing laser light on gallium arsenide (GaAs) to create excitons.

 

Excitons are formed when a photon strikes a material, particularly a semiconductor. If an electron is knocked loose, or excited, it leaves what is termed an “electron hole” behind. If the forces of other charges nearby keep the electron close enough to the hole to feel an attraction, a bound state forms known as an exciton. Excitons are called quasiparticles because the electrons and holes behave together as if they were a single particle.

 

If this all sounds a bit hard to relate to, consider that solar cells are semiconductors, and the formation of excitons is one possible step to the production of electricity. A better understanding of how excitons form and behave could produce ways to harvest sunlight more efficiently.

 

Graduate student Andrew Almand-Hunter was forming biexcitons – two excitons that behave like a molecule, by focusing the laser to a dot 100nm across and leaving it on for shorter and shorter fractions of a second.

 

“But the experiment didn’t behave at all in the way we expected,” Almand-Hunter said. When the pulses were lasting less than 100 millionths of a second exciton density reached a critical threshold. “We expected to see the energy of the biexcitons increase as the laser generated more electrons and holes. But, what we saw when we did the experiment was that the energy actually decreased!” 

 

The team figured that they had created something other than biexcitons, but were not sure what. They contacted theorists at Philipps-University, Marburg who suggested they had made droplets of 4, 5 or 6 electrons and holes, and constructed a model of these dropletons' behavior. 

 

The dropletons are small enough to behave quantum mechanically, but the electrons and holes are not in pairs, as they would be if the dropleton was just a group of excitons. Instead they form a “quantum fog” of electrons and holes that flow around each other and even ripple like a liquid, rather than existing as discrete pairs. However, unlike liquids we are familiar with, dropletons a finite size, outside which the electron/hole association breaks down.

 

The discovery has been published in Nature. Perhaps the most remarkable thing is that the dropletons are stable, by the standards of quantum physics. While they can only survive inside solid materials, they last around 25 trillionths of a second, which is actually long enough for scientists to study the way their behavior is shaped by the environment. At 200nm wide the dropletons are as large as very small bacteria – a size that can be seen by conventional microscopes.

 

"Classical optics can detect only objects that are larger than their wavelengths, and we are approaching that limit," Mackillo Kira of Philipps-University who provided much of the theoretical grounding told Scientific American. "It would be really neat to not only detect spectroscopic information about the dropleton, but to really see the dropleton." 

 

JILA lab leader Professor Steven Cundiff says, “Nobody is going to build a quantum droplet widget." However, the work could help in the understanding of systems where multiple particles interact quantum mechanically.

Read more at http://www.iflscience.com/physics/new-state-matter-discovered#xu774hUPaKm1DPIT.99

Scientists have made light appear to break Newton’s third law

Laser pulses have been made to accelerate themselves around loops of optical fibre-  which seems to go against Newton’s 3rd law. This states that for every action there is an equal and opposite reaction. This new research exploits a loophole with light that makes it appear to have mass.

Under Newton’s third law of motion, if we imagine one billiard ball striking another upon a pool table, the two balls will bounce away from each other. If one of the billiard balls had a negative mass, then the collision of the two balls would result in them accelerating in the same direction. This effect could be used in a diametric drive, where negative and positive mass interact for a continuously propulsive effect. Such a drive also relies on the assumption that negative mass has negative inertia. 

Quantum mechanics however states that matter cannot have a negative mass. Negative mass is not the same as antimatter, as even antimatter has positive mass. Negative mass is a hypothetical concept of matter where mass is of opposite sign to the mass of normal matter. Negative mass is used in speculative theories, such as the construction of wormholes. Should such matter exist, it would violate one or more energy conditions and show strange properties. No material object has ever been found that can be shown by experiment to have a negative mass.

Experimental physicist Ulf Peschel and his colleagues at the University of Erlangen-Nuremberg in Germany have now made a diametric drive using effective mass.. Photons travelling at the speed of light have no rest mass. Shining pulses of light into layered materials like crystals means some of the photons can be reflected backwards by one layer and forwards by another. This delays part of the pulse and interferes with the rest of the pulse as it passes more slowly through the material.

When a material such as layered crystals slows the speed of the light pulse in proportion to its energy, it is behaving as if it has mass. This is called effective mass, which is the mass that a particle appears to have when responding to forces. Light pulses can have a negative effective mass depending on the shape of their light waves and the structure of the crystal material that the light waves are passing through. To get a pulse to interact with material with a positive effective mass means finding a crystal that is so long that it can absorb the light before different pulses show a diametric drive effect.

Peschel therefore created a series of laser pulses in two loops of fibre-optic cable to get around these requirements. The pulses were split between the loops at a contact point and the light kept moving around each light in the same direction. The key to the experiment was having one loop slightly longer than the other. This meant light going around the longer loop is relatively delayed, as shown by the diagram.

When the light completes a circuit and splits at the contact point, some of its photons are shared with pulses within the other loop. After a few circuits, the pulses develop an interference pattern that gives them effective mass.

The team were thus able to create pulses with both positive and negative effective mass. When the opposing pulses interacted in the loops, they accelerated in the same direction and moved past the detectors a little bit earlier after each trip. The loops are essentially the equivalent of having extremely long crystals.

As electrons in semiconductors can also have effective mass, loops could be used to speed them up and boost computers’ processing power. The loops could also be used to control a fibre’s colour output. It is hoped this will also lead to faster electronics as well as more reliable communications.

Photo Gallery

Quantum Switches Controlled By Single Photons

Quantum computing has the potential to revolutionize computing by exponentially increasing speed, computing power, and security as single atoms would be capable of performing tasks. Though quantum computing is probably overkill for the typical person, it holds a great deal of promise for researchers and others who need ramped up computing. A team of researchers led by Mikhail Lukin of Harvard University have demonstrated an ability to use single atoms as gates that can block the flow of electrons and can be operated with one photon. The details of the research have been described in Nature. 

“Conceptually, the idea is very simple,” Lukin told the Harvard Gazette. “Push the conventional light switch to its ultimate limit. What we’ve done here is to use a single atom as a switch that, depending on its state, can open or close the flow of photons … and it can be turned on and off using a single photon.” When many switches are added together, it could essentially act like a computer.

Lukin is currently eyeing the possibility of putting this technology into fiber-optic cables, which would offer maximum security through encryption. While there are short-range possibilities with this technology, the quantum switches could increase the distance by which information could be securely transmitted from tens of kilometers up to thousands of kilometers.

The researchers developed a system that combined the photon switches with traditional vacuum tubes. “Conventional computers were initially built using vacuum tubes, and people eventually developed integrated circuits used in modern computers,” Lukin went on to say in the Harvard Gazette. “Where quantum systems stand today, the best systems are still analogous to vacuum tubes. They typically use vacuum chambers to isolate and hold single atoms using electromagnetic fields.”

Once the atoms have been captured in the vacuum tubes, lasers act like optical tweezers to hold one and then chill it nearly to absolute zero. The atom is then moved near the chip before it is blasted with microwaves and enters a state of quantum superposition. This state is so delicate that getting hit with even a single photon is capable of changing it. 

These switches probably won’t see action inside a quantum network for about another decade, as there are different approaches that are more advanced, according to Jeff Thompson; a grad student who is co-author of the paper. However, these single-atom switches can interact with light that travels through optical fibers, making this next-generation computing possible.

[The main image is credited to NASA/Goddard Space Flight Center and has been used in accordance with CC BY 2.0]