Relativity is Right on Time, Again

time dilation

Special relativity predicts that a twin in a high-speed rocket, as viewed by his Earth-bound brother, will have a slower-ticking clock. A precise test of this time dilation, first performed in 1938, involves observing the frequency shift—or “ticking” change—in the electronic transitions of fast-moving ions. An update of this type of experiment using lithium ions has now verified special relativity’s prediction with unprecedented accuracy—a result that provides additional constraints on quantum gravity models.

Relativistic time dilation derives from Lorentz invariance: a physical measurement should be independent of the orientation or speed of the lab’s reference frame. As fundamental as Lorentz invariance might sound, certain quantum gravity theories, such as string theory, predict its violation at a very small level. Physicists have therefore devised a whole host of Lorentz violation tests, one of which involves measuring time dilation. Continue reading Relativity is Right on Time, Again

Astrophysicists Identify The “Habitable” Regions Of The Entire Universe

It’s not just stars and galaxies that have habitable zones. Some regions of universe are more life-friendly than others

Gamma ray bursts are among the most powerful events in the universe. And although the SGR 1806 -20 flare was relatively mild, it was an unwelcome reminder that life on this planet is constantly threatened by events of unimaginable power.

But here’s the thing: gamma ray bursts are much more common in some parts of the universe than others. That raises the curious prospect that some parts of the universe ae much more inhospitable to life than others. So where are these death zones and what kind of constraints do they place on the origin of life?

Today, Tsvi Piran at The Hebrew University in Jerusalem, Israel and Raul Jimenez at Harvard University in Cambridge say they’ve worked out where in the universe gamma ray bursts are most deadly. As a result, they are able to work out for the first time the universe’s habitable zones.

Gamma ray bursts are a significant mystery—nobody is quite sure how or where the most powerful ones occur. But astronomers know that a burst could do significant damage to the Earth if it happened nearby. The gamma rays would rapidly strip the planet of its ozone layer, leaving the creatures on the surface vulnerable to ultraviolet light and other kinds of high-energy radiation. Indeed, several studies have examined the very real possibility that gamma ray bursts may have brought life on Earth to the edge of extinction on several occasions in the past.

Exactly how often a given planet would be hit by gamma ray bursts obviously depends on its neighbourhood. So the starting point for the work of Prian and Jimenez is to determine how common these powerful events are. Continue reading Astrophysicists Identify The “Habitable” Regions Of The Entire Universe

The 2014 Ig Nobel Prize Winners

The 2014 Ig Nobel Prizes were awarded on Thursday night, September 18th, 2014 at the 24th First Annual Ig Nobel Prize Ceremony, at Harvard’s Sanders Theatre. The ceremony was webcast live.

PHYSICS PRIZE [JAPAN]: Kiyoshi Mabuchi, Kensei Tanaka, Daichi Uchijima and Rina Sakai, for measuring the amount of friction between a shoe and a banana skin, and between a banana skin and the floor, when a person steps on a banana skin that’s on the floor.

REFERENCE: “Frictional Coefficient under Banana Skin,” Kiyoshi Mabuchi, Kensei Tanaka, Daichi Uchijima and Rina Sakai, Tribology Online 7, no. 3, 2012, pp. 147-151.

WHO ATTENDED THE CEREMONY: Kiyoshi Mabuchi
Continue reading The 2014 Ig Nobel Prize Winners

Who is Alexander Grothendieck?

Anarchy, Mathematics, Spirituality, SolitudeAGportraitAlexander Grothendieck is one of the most prominent mathematicians of the twentieth century, notably in that he revolutionized algebraic geometry.
His life contains unusual drama.
In 1970, at the age of 42 and after a brilliant scientific career, he gave up his professorship at the renowned Institut des Hautes Etudes Scientifiques in Paris and withdrew from scientific activity and soon after from mathematical research.
For a few years he devoted himself to the peace movement and the emerging ecology movement. Eventually his life became increasingly guided by philosophical, religious and esoteric ideas.
Initially Buddhism played an important role, but later he drew closer to a more Christian vision. He wrote a much discussed retrospective account of his time as a mathematician, entitled Récoltes et Semailles (Reaping and Sowing), and composed other philosophical meditations which remain largely unknown.
In 1991, after undergoing severe psychological crises, he unexpectedly disappeared from view….
… Read more at www.imj-prg.fr

Water-based nuclear battery can be used to generate electrical energy

Long-lasting batteries could be used for emergency equipment and in spaceflight

Structure and mechanism of the plasmon-assisted radiolytic water splitter

Structure and mechanism of the plasmon-assisted radiolytic water splitter

COLUMBIA, Mo. – From cell phones to cars and flashlights, batteries play an important role in everyday life. Scientists and technology companies constantly are seeking ways to improve battery life and efficiency. Now, for the first time using a water-based solution, researchers at the University of Missouri have created a long-lasting and more efficient nuclear battery that could be used for many applications such as a reliable energy source in automobiles and also in complicated applications such as space flight.

“Betavoltaics, a battery technology that generates power from radiation, has been studied as an energy source since the 1950s,” said Jae W. Kwon, an associate professor of electrical and computer engineering and nuclear engineering in the College of Engineering at MU. “Controlled nuclear technologies are not inherently dangerous. We already have many commercial uses of nuclear technologies in our lives including fire detectors in bedrooms and emergency exit signs in buildings.”

The battery uses a radioactive isotope called strontium-90 that boosts electrochemcial energy in a water-based solution. A nanostructured titanium dioxide electrode (the common element found in sunscreens and UV blockers) with a platinum coating collects and effectively converts energy into electrons.

“Water acts as a buffer and surface plasmons created in the device turned out to be very useful in increasing its efficiency,” Kwon said. “The ionic solution is not easily frozen at very low temperatures and could work in a wide variety of applications including car batteries and, if packaged properly, perhaps spacecraft.”

The research, “Plasmon-assisted radiolytic energy conversion in aqueous solutions,” was conducted by Kwon’s research group at MU, and was published in Nature.

missouri.edu

Hubble Helps Find Smallest Known Galaxy Containing a Supermassive Black Hole

M60_Astronomers using data from NASA’s Hubble Space Telescope and ground observation have found an unlikely object in an improbable place — a monster black hole lurking inside one of the tiniest galaxies ever known.

The black hole is five times the mass of the one at the center of our Milky Way galaxy. It is inside one of the densest galaxies known to date — the M60-UCD1 dwarf galaxy that crams 140 million stars within a diameter of about 300 light-years, which is only 1/500th of our galaxy’s diameter.

If you lived inside this dwarf galaxy, the night sky would dazzle with at least 1 million stars visible to the naked eye. Our nighttime sky as seen from Earth’s surface shows 4,000 stars.

The finding implies there are many other compact galaxies in the universe that contain supermassive black holes. The observation also suggests dwarf galaxies may actually be the stripped remnants of larger galaxies that were torn apart during collisions with other galaxies rather than small islands of stars born in isolation.

“We don’t know of any other way you could make a black hole so big in an object this small,” said University of Utah astronomer Anil Seth, lead author of an international study of the dwarf galaxy published in Thursday’s issue of the journal Nature. Continue reading Hubble Helps Find Smallest Known Galaxy Containing a Supermassive Black Hole