In 2,015 researchers at the Laser Interferometer Gravitational-Wave Observatory (LIGO) captured the first direct evidence of gravitational waves, more than a century after the phenomenon was first proposed.
Gravitational-wave events have only been detectable for a few years, and a new study shows the remarkable diversity of waves caused by black hole mergers.
A team of international scientists, including researchers from The Australian National University (ANU), have unveiled the largest number of gravitational waves ever detected.
The discoveries will help solve some of the most complex mysteries of the Universe, including the building blocks of matter and the workings of space and time.
Continue reading “Scientists detect a ‘tsunami’ of gravitational waves” »
In a new report now published in Science, primary authors Zhen Zhu, Michal Papaj, and an international research team in physics, materials science, and condensed matter at the Jiao Tong University, China, Massachusetts Institute of Technology, U.S., and the Chinese Academy of Sciences discovered the Fermi surface of supercurrent-induced quasiparticles in a superconducting system for the first time. This discovery comes 50 years after the initial theoretical prediction was made by physicist Peter Fulde and revealed the impact of the finite Cooper pair momentum on the quasiparticle spectrum. In condensed matter physics, Cooper pairs are a pair of electrons with opposite spins loosely bound due to electron-lattice interactions. Superconductivity is based on their condensation to Bosonic states at low temperatures. The interplay of superconductivity and magnetic fields leads to the phenomenon of a ‘segmented Fermi surface. A leading author of this work, MIT Professor of Physics Liang Fu, outlined the significance of this discovery.
Supercurrent flow in a superconductor
Physicists assume that a sufficiently large supercurrent can close the energy gap in a superconductor and create gapless quasiparticles via the Doppler shift of quasiparticle energy. This is facilitated by the finite momentum of Cooper pairs in the presence of supercurrent flow in a superconductor, where the shift in Cooper pair momentum can result in a Doppler shift. In this work, Zhu et al. used quasiparticle interference to image the field-controlled Fermi surface of bismuth telluride (Bi2Te3) thin films proximitized by the superconductor niobium diselenide (NbSe2). A small applied in-plane magnetic field induced a screening supercurrent, which led to finite momentum pairing on the topological surface states of Bi2Te3. The scientists identified distinct interference patterns to indicate a gapless superconducting state with a segmented Fermi surface to reveal the strong impact of the finite Cooper pair momentum on the quasiparticle spectrum.
Fusion power plants use magnetic fields to hold a ball of current-carrying gas (called a plasma.
Plasma is one of the four fundamental states of matter, along with solid, liquid, and gas. It is an ionized gas consisting of positive ions and free electrons. It was first described by chemist Irving Langmuir in the 1920s.
The Big Bang still happened a very long time ago, but it wasn’t the beginning we once supposed it to be.
Where did all this come from? In every direction we care to observe, we find stars, galaxies, clouds of gas and dust, tenuous plasmas, and radiation spanning the gamut of wavelengths: from radio to infrared to visible light to gamma rays. No matter where or how we look at the universe, it’s full of matter and energy absolutely everywhere and at all times. And yet, it’s only natural to assume that it all came from somewhere. If you want to know the answer to the biggest question of all — the question of our cosmic origins — you have to pose the question to the universe itself, and listen to what it tells you.
Today, the universe as we see it is expanding, rarifying (getting less dense), and cooling. Although it’s tempting to simply extrapolate forward in time, when things will be even larger, less dense, and cooler, the laws of physics allow us to extrapolate backward just as easily. Long ago, the universe was smaller, denser, and hotter. How far back can we take this extrapolation? Mathematically, it’s tempting to go as far as possible: all the way back to infinitesimal sizes and infinite densities and temperatures, or what we know as a singularity. This idea, of a singular beginning to space, time, and the universe, was long known as the Big Bang.
Fusion – combining atomic nuclei to release energy – is a clean and safe way to power our homes and industry. This ‘holy grail’ of energy has eluded physicists for decades, but there are signs that a bright future could be on the horizon.
Thanks to LastPass for sponsoring PBS DS. You can check out LastPass by going to https://lastpass.onelink.me/HzaM/2019Q3JulyPBSspace.
PBS Member Stations rely on viewers like you. To support your local station, go to: http://to.pbs.org/DonateSPACE
It’s one of the most fascinating aspects of the natural world: shapes repeat over and over. The branches of a tree extending into the sky look much the same as blood vessels extending through a human lung, if upside-down. The largest mammal, the whale, is a scaled-up version of the smallest, the shrew. Recent research even suggests the structure of the human brain resembles that of the entire universe. It’s everywhere you look, really. Nature reuses its most successful shapes.
Theoretical physicist Geoffrey West of the Santa Fe Institute in New Mexico is concerned with fundamental questions in physics, and there are few more fundamental than this one: why does nature continually reuse the same non-linear shapes and structures from the smallest scale to the very largest? In a new Big Think video (see above), West explains that the scaling laws at work are nothing less than “the generic universal mathematical and physical properties of the multiple networks that make an organism viable and allow it to develop and grow.”
Continue reading “Could a pill that lowers our body temperature make us live longer?” »
To check out any of the lectures available from Great Courses Plus go to http://ow.ly/dweH302dILJ
We’ll soon be capable of building self-replicating robots. This will not only change humanity’s future but reshape the galaxy as we know it.
American astrophysicists have used the Decadal Survey (DS)—also called Astro 2020 and produced by the National Academies of Science—to recommend a space telescope capable of photographing potentially habitable worlds.
The report recommends that a flagship space observatory will need a six-meter mirror to “provide an appropriate balance between scale and feasibility.”
An eight-meter aperture telescope of the scale of LUVOIR-B would be unlikely to launch before the late 2040… See more.
