Science

Einstein’s theory of gravity — general relativity — has been very successful for more than a century. However, it has theoretical shortcomings. This is not surprising: the theory predicts its own failure at spacetime singularities inside black holes — and the Big Bang itself.

Unlike physical theories describing the other three fundamental forces in physics — the electromagnetic and the strong and weak nuclear interactions — the general theory of relativity has only been tested in weak gravity.

If you have a rhododendron in your garden or pass one by on an afternoon walk perhaps you think of it as just a colourful and pretty shrub. You may have heard that they come from the Himalayas, and that they are invasive plants that destroy ecosystems.

Neither of these is quite accurate. Rhododendrons have an ancient legacy older than the Himalayas and a history intertwined with poison, medicine and folklore.

Rhododendrons may be deciduous or evergreen, anything from a tree to a creeping dwarf shrub, with leaves a centimetre to a foot long, and flowers any shade of white, yellow, orange, pink, red or purple. There are around 1000 species in total, and modern DNA-based work confirms that all “azaleas” are in fact species of rhododendron.

Rhododendron fossil pollen is easy to identify, as are rhododendron seeds, and some of these fossils are 60 million years old. By contrast, the Himalayas as we know them only began forming 50 million years ago, when India collided with Asia. So while around half of all rhododendron species are endemic to the Himalayas (meaning they grow nowhere else), the genus cannot have originated there.

Over 60 million years rhododendrons spread around the northern hemisphere, from boreal woods and high mountains, to tropical rainforests, where many species perch on high branches as epiphytes (a plant or plant-like organism that grows on the surface of another plant). They reached North America, Japan, parts of Europe, most of Asia and even Australia. It was native in the British Isles for a while, until the later ice ages drove it out.

But the mountain ranges and plunging valleys of the Himalayas created a dizzying diversity of rhododendrons as neighbouring populations were isolated from each other. Tourists flock to see the colorful blooms found there, especially in Yunnan and the Baili areas of China.

Rhododendron pollen has microscopic tentacles that make it sticky. Pollen shoots out from the stamens like strings from a party popper when triggered by the buzzing of an insect, and drapes itself across the body of the pollinator.

Rhododendron pollen shoots out in strings. Richard Milne, CC BY-SA

Detractors might say rhododendrons are invasive. But that only applies to one species out of over a thousand – the nefarious Rhododendrom ponticum. If left uncontrolled, this particular rhododendron will eventually dominate the habitat to the virtual exclusion of all other plant life. Other species do not have this problem.

Folklore remedies with risks

There is also far more to humanity’s relationship with rhododendrons than horticultural beauty, and the never-ending battle against Rhodendrom ponticums in the wetter parts of Britain. Rhododendrons have been used to treat everything from colds and diarrhoea through leprosy and STDs, to flagging sex drive and diseases of pigs. Few of these have been tested scientifically.

In Labrador, north-east Canada, infusions of the local rhododendron are commonly drunk. People claim it has many health benefits, but the evidence is limited.

But like so many medicinal plants, some rhododendrons are poisonous, and not to be consumed by the unwary. Some species, including the common yellow azalea, contain toxins in their nectar, which can cause sickness and bad “trips” in humans.

A seven-year space voyage came to its climactic end Sunday when a NASA capsule landed in the desert in the US state of Utah, carrying to Earth the largest asteroid samples ever collected.

Scientists have high hopes for the sample, saying it will provide a better understanding of the formation of our solar system and how Earth became habitable.

The Red Sea's spectacular coral reefs face a new threat, marine biologists warn -- the mass death of sea urchins that may be caused by a mystery disease.

Because the long-spined creatures feed on algae that can suffocate corals, their die-off could "destroy our entire coral reef ecosystem", warned scientist Lisa-Maria Schmidt.

Tropical Cyclone 16 is threatening to hit millions of Americans on the East Coast Saturday and Sunday and the National Hurricane Center has issued a warning that winds could top out at 65 miles per hour, according to the latest forecast issued Friday morning.

"Swells generated by this system will affect much of the U.S. East Coast through the weekend, likely causing life-threatening surf and rip currents," the report from the National Hurricane Center said.

A mystery illness is decimating the chicks of New Zealand's endangered yellow-eyed penguins, and scientists say they may have found the cause.

The flightless birds, endemic to New Zealand, stand lower than knee-high, have pale yellow eyes and sport a band of yellow feathers around the head.

NASA's first mission to retrieve an asteroid sample and return it to US soil is expected to reach a perilous finale on Sunday with a descent into the Utah desert.

Scientists hope the material -- possibly the most ever retrieved by such a mission -- will provide humanity with a better understanding on the formation of our solar system and how Earth became habitable.

Have you ever wondered what a kangaroo’s social life looks like? Well, kangaroos have stronger bonds to one another than you might think.

Over six years, we monitored a population of around 130 eastern grey kangaroos near Wollar in New South Wales to see how their relationships changed over time. Keeping tabs on individual roos led to some surprising results.

There is nothing quite like a diamond. For many they are the ultimate “I love you” gift, and jewellers will tell you the ultra-hard stones have unmatched “fire” and “brilliance”. The sentimental and aesthetic value of the gems is matched by their price, which can run to tens of thousand dollars per carat – and even more for colored diamonds, especially if they are blue, green, violet, orange, red or pink.

But why are diamonds so expensive? How do they form? Do we really find diamonds in volcanoes? What is the link to supercontinents and ancient lifeforms?

Archaeologists said on Wednesday they have unearthed the oldest wooden structure ever discovered, dating from nearly half a million years ago, which suggests that our ancestors may have been more advanced than previously thought.

The exceptionally well-preserved wooden structure was found at Kalambo Falls in the north of Zambia near the border with Tanzania.

NASA’s independent study team released its highly anticipated report on UFOs on Sept. 14, 2023.

In part to move beyond the stigma often attached to UFOs, where military pilots fear ridicule or job sanctions if they report them, UFOs are now characterized by the U.S. government as UAPs, or unidentified anomalous phenomena.