Time feels like the most basic feature of reality. Seconds tick, days pass and everything from planetary motion to human memory seems to unfold along a single, irreversible direction. We are born and we die, in exactly that order. We plan our lives around time, measure it obsessively and experience it as an unbroken flow from past to future. It feels so obvious that time moves forward that questioning it can seem almost pointless.

And yet, for more than a century, physics has struggled to say what time actually is. This struggle is not philosophical nitpicking. It sits at the heart of some of the deepest problems in science.

Modern physics relies on different, but equally important, frameworks. One is Albert Einstein’s theory of general relativity, which describes the gravity and motion of large objects such as planets. Another is quantum mechanics, which rules the microcosmos of atoms and particles. And on an even larger scale, the standard model of cosmology describes the birth and evolution of the universe as a whole. All rely on time, yet they treat it in incompatible ways.

When physicists try to combine these theories into a single framework, time often behaves in unexpected and troubling ways. Sometimes it stretches. Sometimes it slows. Sometimes it disappears entirely.

The main reason why this process isn't "something for nothing" is that it takes twice as much electrical energy to produce energy in the form of gasoline. As Aircela told The Autopian:

Aircela is targeting >50% end to end power efficiency. Since there is about 37kWh of energy in a gallon of gasoline we will require about 75kWh to make it. When we power our machines with standalone, off-grid, photovoltaic panels this will correspond to less than $1.50/gallon in energy cost.

Doesn't it sort of defeat the purpose of gasoline being used because it's so energy dense? Like, this seems to suggest little more than the benefits of electrification in transport.

Scientists investigating video of a cow using tools, and later conducting some basic psychology experiments on said cow, say their findings could expand the list of animals capable of tool use.

Some 10,109 doctoral-trained experts in science and related fields left their jobs last year as President Donald Trump dramatically shrank the overall federal workforce. That exodus was only 3% of the 335,192 federal workers who exited last year but represents 14% of the total number of Ph.D.s in science, technology, engineering, and math (STEM) or health fields employed at the end of 2024 as then-President Joe Biden prepared to leave office.

The numbers come from employment data posted earlier this month by the White House Office of Personnel Management (OPM). At 14 research agencies Science examined in detail, departures outnumbered new hires last year by a ratio of 11 to one, resulting in a net loss of 4224 STEM Ph.D.s. The graphs that follow show the impact is particularly striking at such scientist-rich agencies as the National Science Foundation (NSF). But across the government, these departing Ph.D.s took with them a wealth of subject matter expertise and knowledge about how the agencies operate.

For close to a century, geoscientists have pondered a mystery: Where did Earth’s lighter elements go? Compared to amounts in the Sun and in some meteorites, Earth has less hydrogen, carbon, nitrogen, and sulfur, as well as noble gases like helium—in some cases, more than 99 percent less.

Some of the disparity is explained by losses to the solar system as our planet formed. But researchers have long suspected that something else was going on too.

Recently, a team of scientists reported a possible explanation—that the elements are hiding deep in the solid inner core of Earth. At its super-high pressure—360 gigapascals, 3.6 million times atmospheric pressure—the iron there behaves strangely, becoming an electride: a little-known form of the metal that can suck up lighter elements.

Study coauthor Duck Young Kim, a solid-state physicist at the Center for High Pressure Science & Technology Advanced Research in Shanghai, says the absorption of these light elements may have happened gradually over a couple of billion years—and may still be going on today. It would explain why the movement of seismic waves traveling through Earth suggests an inner core density that is 5 percent to 8 percent lower than expected were it metal alone.

Electrides, in more ways than one, are having their moment. Not only might they help solve a planetary mystery, they can now be made at room temperature and pressure from an array of elements. And since all electrides contain a source of reactive electrons that are easily donated to other molecules, they make ideal catalysts and other sorts of agents that help to propel challenging reactions.

In our latest attempts to make lab rats immortal, a new compound has been shown to reverse late stage Alzheimer's disease in lab mice. This is a rare case where the title isn't even clickbait.

NGC 55: A Galaxy of Nebulas

Can you see nebulas in other galaxies? Yes, some nebulas shine brightly enough -- if you know how to look. Clouds of hydrogen and oxygen emit light at very specific colors, and by isolating them, astronomers and astrophotographers can reveal structures that would otherwise be too faint to notice. This deep, 50-hour exposure highlights glowing hydrogen (red) and oxygen (blue) across galaxy NGC 55, viewed nearly edge-on.

Also known as the String of Pearls Galaxy, NGC 55 is often compared to our Milky Way's satellite galaxy the Large Magellanic Cloud (LMC), although NGC 55 lies much farther away at about 6.5 million light-years. The resulting image uncovers a sprinkling of emission nebulas within and sometimes above the galaxy's dusty disk, offering a detailed look at distant star-forming regions.

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Boffins at the Department of Energy's Sandia National Labs are working to develop cheap and power efficient LEDs to replace lasers. One day, they let a trio of AI assistants loose in their lab.

Five hours later, the bots had churned through more than 300 tests and uncovered a novel approach for steering LED light that is four times better than methods the researchers developed using their own wetware.

The work, detailed in a paper published in the journal Nature Communications underscores how AI agents are changing the way scientists work.

"We are one of the leading examples of how a self-driving lab could be set up to aid and augment human knowledge," Sandia researcher Prasad Iyer said in a recent blog post.

The experiment builds on a 2023 paper in which Iyer and his team demonstrated a method for steering LED light that has applications in everything from autonomous vehicles to holographic projectors. The trick was finding the right combination of parameters to steer the light in the desired manner, a process researchers expected to take years.

The photo shows towering mountains made of solid water ice and smooth plains of frozen nitrogen on Pluto's surface, lit by the distant Sun.

NASA's New Horizons spacecraft took its first detailed, close-up pictures of Pluto's surface during its historic flyby on July 14, 2015.

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This moon is doomed. Mars, the red planet named for the Roman god of war, has two tiny moons, Phobos and Deimos, whose names are derived from the Greek for Fear and Panic.

These Martian moons may well be captured asteroids originating in the main asteroid belt between Mars and Jupiter or perhaps from even more distant reaches of our Solar System.

The larger moon, Phobos, is indeed seen to be a cratered, asteroid-like object in this stunning color image from the robotic Mars Reconnaissance Orbiter, which can image objects as small as 10 meters. But Phobos orbits so close to Mars - about 5,800 kilometers above the surface compared to 400,000 kilometers for our Moon - that gravitational tidal forces are dragging it down. In perhaps 50 million years, Phobos is expected to disintegrate into a ring of debris.

Attribution: NASA, LPL, MRO, HiRISE

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Scientists have been forced to rethink the intelligence of cattle after an Austrian cow named Veronika displayed an impressive – and until now undocumented – knack for tool use.

Witgar Wiegele, an organic farmer and baker from a small town in Carinthia near the Italian border, keeps Veronika as a pet and noticed that she occasionally played with sticks and used them to scratch her body.

Wiegele said Veronika began playing with pieces of wood years ago, then worked out how to scratch herself with sticks. He said she also recognised family members’ voices and hurried to meet them when they called.

“I was naturally amazed by her extraordinary intelligence and thought how much we could learn from animals: patience, calmness, contentment, and gentleness,” he said.

Word soon got around and before long a video clip of the cow’s behaviour reached biologists in Vienna who specialise in animal intelligence. They immediately grasped the importance of the footage. “It was a cow using an actual tool,” said Dr Antonio Osuna Mascaró at the city’s University of Veterinary Medicine. “We got everything ready and jumped in the car to visit.”

A Beijing-based energy company has taken a major step toward commercial airborne wind power after completing the maiden flight and grid-connected power generation test of its megawatt-class system in Southwest China.

The test took place on Sunday in Yibin, Sichuan Province, where the floating wind power platform rose to about 6,560 feet (2,000 meters) and successfully delivered electricity to the grid, as reported by China’s state-backed Global Times.

An experimental mRNA treatment has converted the liver into an immune cell "nursery" that pumped out greater numbers of healthy T cells in mice. Since the immune system has a powerful effect on other things like organ health and inflammation, it is hoped that such a treatment in humans might significantly expand our "healthspan", keeping us healthier and more disease-free later in life.

Each time Matthew Zipple, a behavioral ecologist at Cornell University, releases a mouse that was born and raised in a laboratory into the green expanse of a field, he is amazed. He transports the mouse in a paper cup, lays the cup on its side in the grass, and takes off the lid. “When the…

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