Oceans are quite noisy places at the best of times, what with the weather, the movement and communication of fish and man-made noises like ships’ engines and sonar devices. However, the biggest cause of noise pollution in the whole underwater ecosystem is the air bubbles gushing from melting glaciers and their icebergs.
Fjords with melting glaciers are far and away the noisiest places in the ocean and generate sounds at all frequencies from 300 to 20,000 Hertz. Glacial calving is certainly noisy, but in a loud, short-lived sort of way. It is the consistent melting of ice from glaciers and their icebergs that is the real noise generator. The air trapped in the ice escapes as bubbles that ‘pop’ as they leave their icy prison, giving a constant, loud, background noise.
This begs the question of what difference will it make to the fjord ecosystem once climate change has reduced the glaciers to the point that they are melting on land instead?
At the moment, fjords with glaciers are foraging hotspots for all sorts of creatures as well as important breeding locations for harbour seals. It is thought they may use the underwater noise of the escaping air to help them hide from killer whales who hunt by listening to locate their prey.
As glaciers retreat on to land, the seals may lose this acoustic camouflage, which would explain why harbour seal populations are declining in fjords where glaciers no longer reach the sea.
Termite mounds can help prevent the spread of deserts into semi-arid ecosystems, according to a new study.
In the parched grasslands and savannas where termites make their home, they have a hugely beneficial effect on the surrounding ecology. Not only do their mounds store nutrients and moisture, but their extensive tunnels allow water to better penetrate the soil.
As a result, vegetation flourishes near termite mounds in ecosystems that are otherwise highly vulnerable to ‘desertification’.
The difference they make is so significant that lands with termite mounds can survive on substantially less annual rainfall than those without the little creatures.
A second advantage they unwittingly provide is to preserve seeds and plant life and this helps their immediate surroundings recover faster when it does eventually rain.
The amount of rain may be the same as in termite-less areas but, because the termite tunnels allow it to penetrate the soil better, the actual effect on plants is as if there had been more rain.
It may be that other mound-building animals such as ants, prairie dogs and gophers have a similar impact but so far there hasn’t been the research to prove it.
Vast ranges of volcanoes lie deep below the waves along the mid-ocean ridges that run like stitches where the earth’s tectonic plates meet.
It has always been assumed that these giants of vulcanism slowly oozed lava into the spaces left by plate movements at a regular, steady pace, having no influence on our world of air thousands of metres above them.
However, a new study shows that actually these undersea volcanoes flare up in regular cycles – some as often as every two weeks, others every 100,000 years or so – and that these eruptions happen almost exclusively in the first six months of every year.
These pulses in lava ejection are apparently tied to short- and long-term changes in the earth’s orbit and to sea-levels and may trigger natural climate swings.
The chains of undersea volcanoes stretch some 37,000 miles around the world’s oceans and produce possibly eight times as much lava as land volcanoes.
A couple of million years ago the heart of our galaxy, the Milky Way, was convulsed in a titanic eruption, driving gases and other materials outward at over 2 million miles an hour.
The aftermath of this mega-explosion can be seen today – billowing clouds of gas tower 30,000 light years above and below the plane of our galaxy.
This enormous structure was discovered five years ago, showing up as a gamma-ray glow in the sky, and being observed in x-rays and radio waves.
There are two possible origins for these massive bubbles of gas – perhaps there was a firestorm of star births at the galaxy’s centre, which would have produced supernovas and blown out the gas. Alternatively, a group of stars could have fallen into the super-massive black hole that lurks there, which would have blasted super-heated gas deep into space.
These bubbles of gas are short-lived in galactic terms, suggesting they are a repeating phenomenon in the Milky Way’s history. Another reason to be glad the earth is out in the backwaters of a spiral arm……
Our sense of touch is far more sensitive than most of us realise – so sensitive that if your finger was the size of the earth, it could feel the difference between houses and cars.
Swedish scientists have investigated the ‘unknown sense’ of tactile perception and found that people can detect nano-scale wrinkles on seemingly smooth surfaces.
Nano-scale? Basically this means we can feel a bump the size of a very large molecule.
These findings could lead to developments such as touch screens for the visually impaired. And as one of the scientist says ‘To make the analogy with vision, it is as if we have just revealed how we perceive colour. Now we can start using this knowledge for tactile aesthetics in the same way that colours and intensity can be combined for visual aesthetics’.
It seems that everyone on the planet with blue eyes has a single, common ancestor – someone from around 6,000 to 10,000 years ago.
The original, default eye colour is brown (which is still the most dominant in most parts of the world) but a genetic mutation way back when “turned off” the ability to produce brown eyes.
Variations in eye colour from brown to green can all be explained by the amount of melanin in the iris, which is governed by a particular gene. Mutations to this gene can reduce the production of melanin, effectively ‘diluting’ brown eyes to blue.
However, studies of blue-eyed people from such diverse populations as those in Jordan, Denmark and Turkey have found that they have very little variation in the amounts of melanin in their eyes. This suggests they are all linked to one ancestor and have all inherited the ‘switch’ that turns off melanin production at the same spot in their DNA.
Scientists have been trying for decades to work out how carbon behaves deep below the Earth’s surface, in fluids 100 miles below the surface and at temperatures of up to 2,100 degrees F
Now it has been revealed that, along with carbon dioxide and methane, Deep Earth also contains a rich variety of organic carbon species that could be responsible for forming diamonds and perhaps even providing food for microbial life.
The theory, called the Deep Earth Water model, suggests that these deep fluids, expelled from descending tectonic plates, may be responsible for transporting building blocks for life up into the shallow Earth.
They may also play a role in the creation of diamonds as scientists have believed for a long time that diamonds form due to chemical reactions involving either carbon dioxide or methane.
On a good day, our computers are so fast they seen almost instantaneous and this is about as fast as silicon can go….
However this silicon-imposed speed and size limitation of computer processors and memory could be overcome if we used “phase-change materials” (PCMs) instead.
These are materials that can switch between two structural phases with different electrical states – one crystalline and conducting and the other glassy and insulating – in billionths of a second.
The smallest silicon-based logic and memory devices are about 20 nanometres in size – around 4,000 times thinner than a human hair- but PCM devices can function down to about 2 nanometres.
The particular PCM researchers have been experimenting with is a chalcogenide glass, which can be melted and recrystallised in half a nanosecond (which is a billionth of a second) using voltage pulses.
In these PCM devices, logic operations and memory are located together rather than separately, as they are in silicon-based computers, and processing speeds could be 500 to 1,000 times faster than the average laptop we use today.
All this – and using less energy than current computers. All of which is great, but since the internet is already creaking at the seams I think it’s a bit like creating cars that can travel at 250 miles an hour when the road network is designed (on a good day) for 70 miles an hour and, in the busiest places, leaves your crawling along at 20……..
Massive galaxies have stopped making their own stars and instead are snacking on their smaller neighbours, according to Australian scientists.
They looked at more than 22,000 galaxies and found that smaller galaxies are very efficient at making stars from gas, but more massive ones produce hardly any stars themselves and instead grow by eating other galaxies.
Our own galaxy, the Milky Way, is at this tipping point and is likely to continue to grow by eating rather than collecting gas. It hasn’t merged with another galaxy for a very long time but scientists can see the remnants of the old galaxies we have cannibalised. The next two galaxies on our menu – in about four billion years – are the Large and Small Magellanic Clouds.
However, we will get a taste of our own medicine a billion years later when we are due to merge with the Andromeda Galaxy which, being the bigger of the two, will consume the Milky Way.
Most of us have heard of Archaeopteryx – the so-called first bird..the missing link if you like, between the dinosaurs that we know from the fossil record and the modern feathered creatures we love to see in our gardens…..
Well – it turns out that dinosaurs were covered in feathers long before they tried to get off the ground.
Modern birds are descendants of a particular branch of medium-sized predatory dinosaurs called therapods. If you think you don’t know what a therapod looked like, think again because Tyrannosaurus Rex was one of these two-legged meat eaters, as was the smaller velociraptor, made famous by the film Jurassic Park.
Just like their descendants, these dinosaurs were warm-blooded and they evolved feathers rather than fur to keep warm because – current thinking says – of their acute colour vision.
Mammals generally have rather poor colour vision because they tended to be nocturnal during the early stages of their evolution, but reptiles and birds have extremely good vision.
Not only did dinosaurs have the three colour receptors for red, green and blue that humans have, but they probably also had (like their closest living relatives today – crocodiles and birds) the ability to see extremely short-wave and ultra-violet light.
Before dinosaurs evolved feathers, they had hairs similar to a mammal’s fur and these hairs gradually turned into feathers which are much better for optical signalling. The broad, flat surface area of feathers allowed for the constant refraction of light which is absolutely essential to produce blues and greens as well as the metallic shimmering we find so attractive about birds’ plumage.
By developing feathers, dinosaurs were able to show off across the colour spectrum and be warm-blooded animals at the same time, which is something mammals have never (yet) managed…