News Feeds

Researchers have developed a 3D-printed device that generates twisting light beams with orbital angular momentum (OAM), a form of rotational energy that can carry more data than regular beams.

Researchers have unlocked a new method for producing one class of 2D material and for supercharging its magnetic properties.

The future of breast cancer screening and risk-reducing strategies is being shaped by artificial intelligence (AI), according to a recent review article.

Theoretical physicists along with an experimental team have found evidence of a quantum spin liquid in a material known as pyrochlore cerium stannate. They achieved this by combining state-of-the-art experimental techniques, including neutron scattering at extremely low temperatures, with theoretical analysis. By measuring the way in which neutrons interact magnetically with the electron spin in pyrochlore, the researchers observed the collective excitations of spins interacting strongly with light-like waves.

The Earth and Moon have been locked in a gravitational dance for billions of years. Each day, as the Earth turns, the Moon tugs upon the oceans of the world, causing the rise and fall of tides. As a result, the Earth’s day gets a little bit longer, and the Moon gets a little more distant. The effect is small, but over geologic time it adds up. About 620 million years ago, a day on Earth was only 22 hours long, and the Moon was at least 10,000 km closer than it is now.

Evidence for this evolving dance in the geological record only goes back about two billion years. Beyond that, the Earth was so very different that there simply isn’t enough evidence to gather. So, instead, we must rely on computational models and our understanding of dynamics. We know that when the Earth formed, it had no large moon. Then, about 4.4 billion years ago, a Mars-sized protoplanet named Theia collided with our world to create the Earth-Moon system. What’s interesting is that most of the computer simulations for this collision generate a Moon that is much closer to the Earth than we’d expect. Early Earth didn’t have vast oceans, so there were no water tides to drive the Moon to a larger orbit. So how did the Moon get to its present distance?

The potential structure of a lava planet. Credit: Farhat, et al

A new study argues that back then the Earth did have tides, but they were made of lava, not water. Just after the Great Collision, Earth would have been covered in an ocean of hot lava. With the Moon so near, the lava would have experienced strong tides. Since lava is much denser than water, the effects of the tide would have been much greater. The Earth’s rotation would have slowed down much faster, and the Moon would quickly become more distant. Based on their simulations, the authors argue that the Moon’s distance would have increased by 25 Earth-radii in just 10,000 to 100,000 years. This would explain how the Moon moved towards its present distance range rather quickly.

The idea of tides on an ocean world also has implications for planets around other stars. Planets that form very close to their sun would be extremely hot, and many of them could have lava oceans for a billion years or more. Simulations of such worlds show that lava tides would accelerate the spin dynamics of such a world and could cause them to become tidally locked on a million-year timescale instead of a billion-year timescale. If this model is correct, it would have a significant impact on potentially habitable worlds. Most exoplanets orbit red dwarf stars, since red dwarfs make up about 75% of the stars in our galaxy. The habitable zone of red dwarfs is very close to the star, meaning that many of them would have begun as lava worlds. This would mean most potentially habitable worlds would have one side always facing the sun, while the other side is forever in the cold. Life on these worlds would be very different from what we see on Earth.

Reference: Farhat, Mohammad, et al. “Tides on Lava Worlds: Application to Close-in Exoplanets and the Early Earth-Moon System.” arXiv preprint arXiv:2412.07285 (2024).

The post Early Earth's Oceans of Magma Accelerated the Moon's Departure appeared first on Universe Today.

Wildlife photos return today, but I have precious few batches in the tank. If you got ’em, please send ’em, lest this feature disappear.

Today UC Davis mathematician Abby Thompson, who survived cancelation, is back with pictures of California tide pools. Abby’s captions are indented, and you can enlarge the photos by clicking on them.

November-December tidepools (Northern California).  The weather at the coast over the Thanksgiving weekend was spectacular- sunny, warm, with no wind; perfect for poking around in the tide pools.    As usual I got help with some of the IDs from people on inaturalist.

Mussel-covered rock (probably Mytilus californianus); I liked the pattern made on the sand as the tide retreated:

Calliostoma ligatum (blue-ringed top snail):

Eupentacta quinquesemita (stiff-footed sea cucumber) Probably; it’s a little hard to tell with sea cucumbers. This one was a couple of inches long.

Hemigrapsus nudus (Purple shore crab). This is one of the most common crabs on this stretch of shore.   This one was small (maybe 2” across the back) but testy, apparently ready to take me on:

Dendronotus subramosus (nudibranch). Nudibranchs are often scarce at this time of year, but the calm sea seems to have brought them out:

Phidiana hiltoni (nudibranch) Posing for the camera:

Anthopleura artemisia (moonglow anemone). I’ve posted a few pictures of this species.   The color varies so much that they all look quite different.   I’ve never seen one that’s blue before; it was striking next to the brilliant orange sponge:

Hermissenda opalescens: (nudibranch):

Cervus canadensis nannodes (Tule elk) from tiny creatures to large (although this species is small for elk). This picture is from Point Reyes National Seashore, where there’s a reserve.    A short, highly recommended hike takes you to where the elk can be found wandering about:

Tomales Point at sunset, as the tide was beginning to turn:

Camera info:  Mostly Olympus TG-7, in microscope mode, pictures taken from above the water.    The last two pictures were taken with my iphone.