Articles by David Appell
Phys.org / A technosignature that could detect an extraterrestrial civilization's reliance on nuclear fusion
Extraterrestrial civilizations need a great deal of energy as they advance up the Kardashev scale. Fossil fuels are finite, wind and solar energy are carbon free but not as efficient as fossil fuels, and traditional nuclear ...
Phys.org / Cosmological model proposes dark matter production during pre-Big Bang inflation
As physicists continue their struggle to find and explain the origin of dark matter, the approximately 80% of the matter in the universe that we can't see and so far haven't been able to detect, researchers have now proposed ...
Medical Xpress / Assessing synchronized activity in the human brain through frequency-dependent covariance analysis
This year is the centennial anniversary of German psychiatrist Hans Berger's invention of electroencephalography (EEG), a way to record electrical activity in the brain, now called brainwaves or neural oscillations. Amazingly, ...
Phys.org / An unexpected delay in a standard quantum optical process generates pairs of photons
Since it was first demonstrated in the 1960s, spontaneous parametric down-conversion (SPDC) has been at the center of many quantum optics experiments that test the fundamental laws of physics in quantum mechanics, and in ...
Phys.org / Observing dark matter at cosmic dawn
After almost a century of speculation, proposals and searches for dark matter, physicists now know that it currently comprises about 27% of the universe's mass-energy, with an abundance over five times that of ordinary matter ...
Phys.org / Researchers find a possible solution to the cosmic ray muon puzzle
Scientists have a problem with cosmic rays—they produce too many muons at the Earth's surface. Cascades of muons are byproducts of high-energy cosmic rays as they collide with nuclei in the upper atmosphere, and scientists ...
Phys.org / Artificial intelligence finds previously undetected historical climate extremes
There are over 30,000 weather stations in the world, measuring temperature, precipitation and other indicators often on a daily basis. That's a massive amount of data for climate researchers to compile and analyze to produce ...
Phys.org / An improved quantification of the intergalactic medium and cosmic filaments
Much of the mass in the universe lies not in stars or galaxies, but in the space between them, known as the intergalactic medium. It is warm and even hot, and is called the "warm-hot intergalactic medium," or WHIM. It holds ...
Phys.org / Ultrawide binary objects in the Kuiper belt may not have come from the earliest solar system, research suggests
Trying to understand the makeup and evolution of the solar system's Kuiper belt has kept researchers busy since it was hypothesized soon after the discovery of Pluto in 1930. In particular, binary pairs of objects there are ...
Phys.org / More comprehensive search for sterile neutrinos comes up empty
Particle physicists have been looking for so-called "sterile neutrinos" for a few decades now. They are a hypothesized particle that would have a tiny mass like the three known neutrinos but would not interact by the weak ...
Phys.org / Hints of a 'neutrino fog' could complicate efforts to detect dark matter
As if searching for dark matter isn't difficult enough already, physicists may have detected another hurdle known as a "neutrino fog" from solar neutrinos streaming through Earth.
Phys.org / A novel state of thorium opens the possibility for a nuclear clock
Why are there atomic clocks but no nuclear clocks? After all, an atom's nucleus is typically surrounded by many electrons, so in principle it should be less susceptible to outside noise (in the form of light). A nucleus, ...
Phys.org / Constraining the body of a hydra can cause it to grow two heads
Hydra are small, invertebrate, predatory animals that live in water. They're tubular, radially symmetric and up to 10 mm long, with a head (mostly a mouth), a single, adhesive foot, and tentacles.
Phys.org / New image recognition technique for counting particles provides diffusion information
A team of scientists have invented a technique to determine the dynamics of microscopic interacting particles by using image recognition to count the number of particles in an imaginary box. By changing the size of the observation ...
Phys.org / Scientists discover a promising way to create new superheavy elements
What is the heaviest element in the universe? Are there infinitely many elements? Where and how could superheavy elements be created naturally?
