James' World 2

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Hydrogen could be an important part of our future energy supply: It can be stored, transported, and burned as needed. However, most of the hydrogen available today is a by-product of natural gas production, and this has to change for climate protection reasons. The best strategy so far to produce environmentally friendly “green hydrogen” is to split water into hydrogen and oxygen using electricity that comes from renewable energy sources, for example, photovoltaic cells.

However, it would be much easier if sunlight could be used directly to split water. This is exactly what new catalysts are now making possible, in a process called “photocatalytic water splitting.” The concept is not yet used industrially. At TU Wien, important steps have now been taken in this direction: on an atomic scale, scientists have realized a new combination of molecular and solid-state catalysts that can do the job while using relatively inexpensive materials.

Interaction of atoms

“Actually, to be able to split water with light you have to solve two tasks at the same time,” says Alexey Cherevan from the Institute for Materials Chemistry at TU Wien. “We have to think about oxygen and about hydrogen. The oxygen atoms of the water must be transformed into O₂ molecules, and the remaining hydrogen ions—which are just protons—must be turned into H2 molecules.”

Solutions have now been found for both tasks. Tiny inorganic clusters consisting of only a small number of atoms are anchored on a surface of light-absorbing support structures such as titanium oxide. The combination of clusters and carefully chosen semiconductor supports lead to the desired behavior.

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Structural models of two clusters that enable water splitting into O2 and H2 by means of light energy. Credit: Vienna University of Technology

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On a series of 70-year-old photographic plates containing images of the night sky, a few astronomers say they’ve found something weird: flashes of light that appear and then disappear, like ghosts.

“We found one image where nine stars were out there, and they vanished. And they are not there half an hour earlier, and they are not there six days later,” says Beatriz Villarroel, a postdoctoral researcher at the Nordic Institute for Theoretical Physics. “And you wonder, ‘Is this real?’”

There isn’t any readily available astronomical explanation for what these vanishing points of light, which the researchers call transients, might be. The dots might be defects in the photographic emulsions or image artifacts from when astronomers first scanned the plates. But in a series of recent papers, Villarroel and a small team of astronomers have been more seriously probing the possibility that the flashes might be something more exciting — extraterrestrial objects.

A shiny, spinning object passing by Earth would leave a line of dots in a long-exposure image of the night sky. Asteroids or meteors aren’t likely to look like that — most asteroids are dark, and meteors are moving so fast they’d look like streaks. And, most intriguingly for the researchers, there weren’t any satellites in the night sky when the images were taken, as all the plates were before the launch of Sputnik.

Still, Villarroel and colleagues haven’t ruled out Earthly explanations for these tantalizing dots. And there’s a long history of events associated with the search for extraterrestrial intelligence (SETI) fizzling out under closer scrutiny.

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In about 5 billion years, the Sun will leave the main sequence and become a red giant. It’ll expand and transform into a glowering, malevolent ball and consume and destroy Mercury, Venus, Earth, and probably Mars.

Can humanity survive the Sun’s red giant phase? Extraterrestrial Civilizations (ETCs) may have already faced this existential threat.

Could they have survived it by migrating to another star system without the use of spaceships?

Universe Today readers are well-versed in the difficulties of interstellar travel. Our nearest neighboring solar system is the Alpha Centauri system.

If humanity had to flee an existential threat in our Solar System, and if we could identify a planetary home in Alpha Centauri, it would still take us over four years to get there – if we could travel at the speed of light!

It still takes us five years to get an orbiter to Jupiter at our technological stage. There’s lots of talk about generation starships, where humans could live for generations while en route to a distant habitable planet.

Those ships don’t need to reach anywhere near the speed of light; instead, entire generations of humans would live and die on a journey to another star that takes hundreds or thousands of years. It’s fun to think about but pure fantasy at this point.

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(Cavan Images/Getty Images)

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If the Great Salt Lake, which has already shrunk by two-thirds, continues to dry up, here’s what’s in store:

The lake’s flies and brine shrimp would die off — scientists warn it could start as soon as this summer — threatening the 10 million migratory birds that stop at the lake annually to feed on the tiny creatures. Ski conditions at the resorts above Salt Lake City, a vital source of revenue, would deteriorate. The lucrative extraction of magnesium and other minerals from the lake could stop.

Most alarming, the air surrounding Salt Lake City would occasionally turn poisonous. The lake bed contains high levels of arsenic and as more of it becomes exposed, wind storms carry that arsenic into the lungs of nearby residents, who make up three-quarters of Utah’s population.

“We have this potential environmental nuclear bomb that’s going to go off if we don’t take some pretty dramatic action,” said Joel Ferry, a Republican state lawmaker, and rancher who lives on the north side of the lake.

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A satellite view of the Great Salt Lake captured in September 1987.Credit…EROS Center, U.S.G.S.

The Great Salt Lake in May 2021.Credit…EROS Center, U.S.G.S.

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In 1905, our conception of the Universe changed forever when Einstein put forth his special theory of relativity. Prior to Einstein, scientists were able to describe every “point” in the Universe with the use of just four coordinates: three spatial positions for each of the three dimensions, plus a time to indicate which moment any particular event occurred. All of this changed when Einstein had the fundamental realization that every single observer in the Universe, dependent on their motion and location, each had a unique perspective on where and when every event in the Universe would have occurred.

Whenever one observer moves through the Universe relative to another, the observer-in-motion will experience time dilation: where their clocks run slower relative to the observer-at-rest. Based on this, Einstein suggested that we could make use of two clocks to put this to the test: one at the equator, which speeds around the Earth at approximately 1670 km/hr (1038 mph), and one at the Earth’s poles, which is at rest as the Earth rotates about its axis.

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This artful illustration of Einstein, some of his equations, and a rendering of a surreal clock helps us conceptualize the differing passage of time experienced by people in different locations and moving at different rates. Although time dilation had been measured for subatomic particles previously, it wasn’t until ~50 years ago that it was measured for an actual clock  (Credit: pasja1000/pixabay)

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