The BepiColombo robotic probe to Mercury is in many ways the most complex space mission yet attempted. For one thing it is actually three spacecraft in one. Two Mercury orbiters, the Mercury Planetary Orbiter (MPO) designed and built by the European Space Agency (ESA) along with the Mercury Magnetospheric Orbiter (MMO) constructed by the Japanese Aerospace Exploration Agency (JAXA). These two scientific missions are stacked together on top of a propulsion module called the Mercury Transfer Module (MTM). Simply organizing a mission combining two probes from two space agencies had to be a challenge.
Artist’s impression of BepiColombo approaching Mercury. (Credit: New Scientist)Breakout of the separate modules of the BepiColombo space probe. (Credit: YouTube)
Still, that was child’s play when compared to the task of getting BepiColombo to Mercury. Launched on 20 October 2018 the spacecraft will not enter orbit around Mercury until 5 December 2025. During that long voyage BepiColombo will flyby and receive gravity assists from Earth once, Venus twice and Mercury itself six times. The difficulty of getting to the Sun’s closest planet is the big reason why there have been more unmanned missions to distant Saturn, two Voyagers plus Cassini, than to comparatively nearby Mercury, one Mariner along with the Messenger mission.
BepiColombo’s complicated flight path to Mercury. (Credit: SlidePlayer)
That
true, although Mercury is actually only about 20% further away from Earth than
Mars is, 90 million kilometers versus 75 million. On the other hand Saturn is
fully 17 times further from Earth than Mars is. So why have we sent more
spacecraft to Saturn than Mercury?
Speed is one big reason. Orbiting so close to the immense gravity of the Sun Mercury has to possess a very high orbital velocity. In fact if you consider the difference in their orbital velocities, delta vee as astronauts put it, Mercury is only a little ‘closer’ to Earth, 18 km/sec, than Saturn is, 20km/sec. And when you’re sending an unmanned robotic probe to an extraterrestrial body the length of time the journey takes doesn’t matter, which makes speed matter more than distance since that requires more fuel.
Another reason that sending a spacecraft to Mercury is difficult is that the nearby Sun’s gravity is so strong, while Mercury’s is rather weak. This makes finding a stable orbit around Mercury rather difficult, especially an orbit that allows you to investigate all of the areas on the planet you want to observe.
Tiny Mercury is so close to the enormous Sun that finding a stable orbit around the planet isn’t easy. (Credit: Forbes)
BepiColombo has just completed the first if it’s flybys, saying a last Goodbye to Earth on the 11th of April, see image below. Later this year in October the probe will make the first of two consecutive flybys of Venus. Hey you known, Venus is big and bright in the evening sky right now so if you go outside on a clear night not long after sundown, BepiColombo will be somewhere between you and that big, bright evening star to the west.
One of the last images of Earth taken by the BepiColombo space probe as it flew by on 11April2020. The spacecraft used Earth’s gravity to give it a push on its way to Venus for its next flyby. (Credit: European Space Agency (ESA))
Once the combined spacecraft finally settles into Mercury orbit the two orbiters / instrument packages will separate and begin their studies of Mercury. The ESA’s MPO orbiter is outfitted with an array of cameras and spectrometers along with a radiometer, a laser altimeter magnetometer and accelerometer for the study of Mercury’s composition as well as compiling a more accurate map of the planet’s surface.
The planet Mercury as photographed by the Messenger space probe. Nice as this image is scientists would like to see a lot more of the details on the planet’s surface. (Credit: The Independent)
Japan’s MMO probe on the other hand carries instruments designed to study Mercury’s extremely thin atmosphere, the planet’s magnetic field and the way in which they both interact with the power of the Solar wind blowing past the planet. The results of these observations could be especially interesting since they will tell us a great deal about how the evolution of both Mercury and nearby Venus were influenced by the power of the Sun.
The Solar Wind has been buffeting the planet for billions of years. How much damage has it caused on Mercury? And how much will it cause on Earth over the next few billion years? (Credit: Scirence / How Stuff Works)
The proposed time frame for the scientific portion of BepiColombo’s mission is for one year after orbital insertion but with the possibility of an additional one-year extension for both orbiters. It’s possible that the success of BepiColombo will not only provide much valuable data about the Sun’s closest planet, but an example of how the space agencies of different nations can work together.
If
only the politicians of different nations followed that example.
Our Stone Age ancestors, often dismissively referred to as ‘Cave Men’ are usually portrayed in movies and TV as being hardly more intelligent than the animals they hunted, or were hunted by. Little by little however archaeologists are uncovering evidence that Stone Age peoples were capable of flashes of genius in solving the problems they faced despite their lack of resources or tools.
Our Stone Age ancestors certainly had it rough but they still possessed technology way beyond that of any animal they completed with! (Credit: Wikipedia)
Finding food is of course the biggest problem any animal faces and a large part of the success of our species, Homo sapiens is the wide variety of different kinds of food we eat, and that includes seafood. Think about it, what are we, an ape scarcely out of the jungle trees doing eating not only fish but clams and mussels, squid and even whale meat.
We humans enjoy a wide variety of food from the oceans, lakes and rivers. No other primate consumes such an abundance of seafood which begs the question, when did we start? (Credit: Miss Vicki Pressure Cooker)
Over the last several decades anthropologists have even developed the hypothesis that it was learning how to make use of the food resources they found along the coast of West Africa that spurred a small population of Homo erectus to become H sapiens. There has even been speculation that the brain boosting fatty acids in the seafood those H erectus ate might have contributed to the growth of the larger brains of their descendants, that’s us.
Homo erectus is generally considered to be our direct ancestor. Was it learned to live off of seafood that turned them into us? (Credit: Ancient News)
Nice
idea, but there’s new evidence coming from the field that is starting to show
that other species of humans were also learning how to feast off of the bounty
of the sea. I’m talking about our cousins the Neanderthals in Europe as much as
106,000 years ago.
The new evidence comes from a cave site along the southern coast of Portugal at Figueira Brava near the town of Setubal. The interior of the cave has been excavated by a team of archaeologists led by Doctor Joăo Zilhăo from the University of Barcelona in Spain.
The cave complex at Figueira Brava in Portugal. It’s easy to see that any inhabitants would be likely to start eating some of the food right on their doorstep. (Credit: CNN.com)
Those excavations have unearthed the bones and other indigestible remains of the animals that the Neanderthals were eating. Those remains clearly show that the Neanderthals were not only hunting the local land fauna of deer, goats, ancient cattle and even horses but were also catching and consuming large amounts mussels, crabs and such fish as eels and sharks! Even the bones of sea mammals like seals and dolphins were discovered in the garbage piles left by the Neanderthals. In fact Doctor Zilhăo and his team estimate that just about half of the diet of the inhabitants of Figueira Brava was in fact seafood.
Patella vulgata shells, a kind of edible snail from the cave at Figueira Brava. (Credit: CNN)
Cracked crab claws from the cave. (Credit: CNN)
So it seems as if our direct ancestors were not the only humans smart enough to realize the enormous benefits to be gained from dinning off of seafood.
Another recent discovery that also demonstrates the intelligence of Neanderthals is the unearthing of the earliest known piece of string from a site in Abri du Maras in southern France. According to the study co-authored by Marie-Hĕlĕne Moncel, Director of Research of the French Nation Centre for Scientific Research (CNRS) the string fragment is dated to between 41,000 and 52,000 years ago. Composed of fibers from the inner bark of a conifer tree the section measures 6.2mm in length by 0.5mm in maximum width.
Fragment of string that’s over 40,000 years old. (Credit: Phys.org)
The string fragment is more than just a few fibers twisted together however. In fact the fragment consists of three separate twisted cords that have been interwoven together, indicating a considerable level of experience in textile production. But more than that the fragment also indicates a considerable knowledge of available natural resources since the fibers come from the inner part of the bark of a tree that, according to botanists, is best obtained during the spring or early summer.
The discovery of this single strand of cord opens up the possibility that Neanderthals may have made extensive use of textiles, perhaps to manufacture bags, nets, ropes, mats or perhaps even cloth? In any case this, oldest piece of string provides further evidence that Neanderthals were anything but brutish animals.
Moving a bit forward in time, to about 25,000 years ago we begin to see the first evidence for actual construction projects by human beings. Some of the most interesting sites come the fertile steppes of Russia south east of Moscow. Here Stone Age hunter-gatherers lived off of one of the largest and most dangerous animals ever pursued by humans, woolly mammoths.
There is plenty of evidence that our Stone Age ancestors did in fact hunt the massive and dangerous Wholly Mammoth. (Credit: The Vintage News)
We know that our ancestors hunted those ice age relatives of elephants because they had the curious habit of building circular walls out of the bones of the mammoths they killed. In a paper published in the journal Antiquity a team led by Alexander Dudin of the Kostenki Museum-Preserve describes the latest, and largest of these mammoth bone structures. Unearthed about 500 kilometers south of Moscow at a site known as Kostenki 11, the ring measures more than 12 meters across and was made from the bones of at least 60 of the huge beasts.
The ring of Mammoth bones at Kostenki 11. (Credit: New York Times)
Because
the other mammoth bone structures found across Eastern Europe are smaller than
the new one at Kostenki scientists had speculated that the circular walls had
once possessed roofs and were used as shelters by the people who made them. At
12 meters across however the mammoth bone circle at Kostenki is too large to be
easily roofed in, leaving the researchers to think of some other possible usage
for the structure.
Whatever
purpose the hunter-gatherers may have had when they built the structures like
Kostenki the fact that they did so clearly shows that like modern humans they
felt the need to adapt their environment to suit their needs by building.
While
it’s true that the earliest structures we humans built were probably used as
dwelling places there is evidence that by 7000 years ago people were already
learning how to build other types of structures as well. Archaeologists in the
Czech Republic have recently discovered a well that they assert is the oldest
known wooden structure.
In a study co-authored by Jaroslav Peška head of the Archaeological Centre in Olomouc the well is described as being built in a square shape some 80 cm to a side and 140 cm in height. Each corner of the square consisted of a vertical oaken tree trunk that had been grooved on its sides to allow flat wooden planks, also oak, to be inserted between them to make the square’s sides. This degree of woodworking ability particularly impressed the researchers. “The shape of the individual structural elements and tool marks preserved on their surfaces confirm sophisticated carpentry skills,” they wrote.
7,000 year old well unearthed in the Czech Republic. The woodworking skills of the makers are still evident after all these years. (Credit: New Scientist)
The technique that was used by the archaeologists to date their discovery is known as dendrochronology and is based on an analysis of the tree rings in the well’s wood. Over the past 50 years or so the tree rings in the wood found at many different archaeological sites across Eastern Europe, and from many different time periods, have been matched up, one to another in order to create a exact timeline that can now be used to very precisely date the wood unearthed at any ancient site in Eastern Europe. This same technique has also been developed in other areas of Europe and the different areas of North America and has been used to precisely date many archaeological sites. Using dendrochronology Doctor Peška and his colleagues have succeeded in dating the year that the trees were felled to either 5255 or 5256 BCE.
By comparing the tree rings in wood from different sites archaeologists have developed an extremely accurate dating technique called dendrochronology. (Credit: Museum of Ontario Archaeology)
As
different as these three archaeological discoveries are, each in its own way
demonstrates that, for all of their primitive tools and crude materials our
ancestors nevertheless were able to think up clever solutions to the problems
they faced in their daily lives. In fact think about it, if they hadn’t been so
bright, we’d still be living in caves ourselves wouldn’t we!
Seems like right now all anybody can talk about is the Covid-19 coronavirus and its effects on our society. That begs the question, or questions, just what is a virus, how do they differ from other pathogenic organisms such as bacteria and what makes them such deadly diseases? Oh, and one more question, are they even living things?
The new symbol of fear for this generation. A false colour electronmicroscopic image of a coronavirus. The protein structures in red form the ‘corona’ that gives this class of viruses their name. (Credit: Live Science)
In order to answer that last question we need to consider exactly what it means to be a living thing. What characteristics do living creatures exhibit that non-living things do not. Without getting too technical I think we can all agree on five characteristics.
If you think about it, exactly what makes a living thing ‘alive’ is really rather complicated. (Credit: Transformation Coaching Magazine)
One:
All living things, whether plant or animal, ingest nutrients.
Second:
Living things metabolize those nutrients.
With
the energy gained from those nutrients living things:
Three:
Grow
Four:
Move
Five: And this is perhaps the most distinguishing characteristic of living things, they reproduce, using a part of their metabolism to create copies of themselves.
Probably the most important difference between living and non-living things is the ability of living things to make copies of themselves, to reproduce. (Credit: SlideShare)
So
what about viruses? Well first of all viruses do not ingest nutrients of any
kind, ever. And without any nutrients viruses simply do not metabolize, at all.
Without the material and energy provided by metabolism viruses neither grow nor
move very much, we’ll see in a moment about the only kind of motion a virus is
capable of.
So what do viruses do? They reproduce, but they can only do so parasitically inside a normal living cell. Basically once a virus is “born” it is little different from a tiny grain of sand or minute crystal, neither growing nor moving by itself.
A few of the many different kinds of Viruses. (Credit: 123RF.com)
However, if a virus ever comes into contact with a living cell within which it is capable of reproduction it will grab that cell like a mousetrap snapping and inject its own genetic material into the cell. That grabbing, snapping and injecting are the only movements that the virus is ever capable of.
Viruses attacking a bacteria. (Credit: PBS)
Once the genetic material is inside the host cell the virus takes over the cell’s life functions and uses the cell’s own metabolism to reproduce hundreds if not thousands of copies of itself. Eventually the host cell bursts apart releasing the new viruses so that they can infect other cells. Viruses are the ultimate parasite having given up all of life’s functions except reproduction and even requiring another life form to do that. Because of this many microbiologists regard viruses as “organisms at the edge of life” rather than true living things. By the way, since viruses do reproduce they are still able to evolve, just like a living thing!
Viruses can only reproduce inside a living cell. The cell is then destroyed in the release of the new viruses. (Credit: Lumen Learning)
O’k,
so if that’s the ‘life cycle’ of a virus, what are they physically? How do they
manage to do what they do?
Well, physically viruses do have genetic material, which can either be in the form of DNA or RNA. All viruses will then have a shell of protein called a capsid surrounding the genetic material and protecting it. Additionally some viruses also have an envelope of fatty, lipid material around the proteins for further protection. That’s it, that’s all a virus consists of, and that’s why most viruses are so small, averaging only about 1/100th the size of a bacteria. In fact viruses are so small that the vast majority can only be seen with the high magnification possible in an electron microscope.
Typical structure of a virus. Not much here just DNA and a protective covering. (Credit: Florida State University)
Now if you’re wondering how did viruses ever evolve to become such complete parasites, how did anything that’s part alive and part not alive ever come into existence? Well you’re not the only one; microbiologists have been debating that question ever since the first virus was discovered back in the 1890s. Currently there are three leading ideas for where viruses came from.
The first idea is that viruses were once more normal cells, probably like bacteria, that became parasitic on other cells for their reproduction. There are in fact bacteria; chlamydia is one example, which can only reproduce inside a host cell. These proto-viruses then would have abandoned all other life functions in order to concentrate on reproduction. Again there are numerous examples of parasites that do this in nature. A tape worm for example has no digestive system, since it lives in your stomach you do its digesting for it. That way it can put more of its metabolism into reproduction. Perhaps viruses went even further, completely giving up metabolism of any kind outside of its host cell.
Tapeworms are common parasites among mammals, including humans. Living in our stomachs and intestines they have lost their own digestive systems in order to concentrate on reproduction. (Credit: Pinterest)
This
idea has gotten a boost recently from a study led by Frank Aylward, Assistant
Professor of Biological Science at Virginia Tech. Professor Aylward and his
colleagues have been studying ‘Giant Viruses’, which are more then ten times
the size of typical viruses. Carrying out a DNA analysis of the ‘Brown Tide Virus’
the researchers found genes directly related to metabolic processes, but why
would organisms that don’t metabolize possess genes for metabolism?
Professor Aylward speculates that the virus uses the metabolic genes to better control the metabolism of the algae cells it infects. Still that leaves the question of where did a virus did metabolic genes from in the first place. One logical answer is that the metabolic genes were simply left over from the time when viruses were independent cells with a metabolism.
The
second idea for a possible origin for viruses is that they evolved from
‘escaped’ bits of DNA or RNA outside of more normal cells. Such ‘Plasmids’ have
been observed to move from one normal cell to another. Indeed single celled
organisms like amoeba are occasionally known to exchange genetic material in
this fashion. Perhaps some of these plasmids began to act for themselves,
taking over the cell that absorbed them, becoming parasitic viruses in the
process.
The final theory for the origin of viruses is simply that viruses evolved in parallel with normal living cells. The problem with this idea is that it’s logically difficult to understand how a proto-virus could use a proto-cell to make copies of itself if the proto-cell is still developing the processes needed to reproduce itself!
As life evolved from the primordial soup to high structured Eukaryota cells where did viruses break off and degenerate into parasites? (Credit: ViroBlogy)
All
three of these hypotheses have some evidence in their favour, all three have
big problems. Which will turn out to be true will only become clear when more
evidence can be gathered.
By the way if you’re wondering, since viruses are so different from living cells, maybe not even alive, how can we kill them? Well, I don’t want to get into a philosophical argument over whether viruses die or are destroyed but fortunately soap and or alcohol will shatter that protein coating they have, exposing the fragile DNA that quickly breaks up. A good reminder to wash your hands often and use hand sanitizer!
Sage Advice! (Credit: Meme Generator)
Most people I suppose pretty much equate viruses with bacteria, after all they both cause diseases in human beings and that’s what we really care about. Most bacteria however are actually beneficial, they spend their lives breaking down dead and decaying organic matter into nutrients that other living things, mostly plants, can ingest. Only a few species of bacteria attack living cells and thereby cause disease.
False colour electronmicroscopic image of viruses attacking bacteria giving an idea of relative sizes. (Credit: Physics World)
Viruses
on the other hand are purely destructive. They don’t do anything other than
reproduce and that reproduction requires the death of a living cell. They are
the ultimate parasite.
Like
everything else nowadays even developments in space exploration are being
impacted by the worldwide coronavirus pandemic. With the disease spreading like
wildfire even NASA hasn’t been spared with personnel at both Cape Kennedy and
the Manned Spaceflight Center in Houston having been tested as positive for the
virus. In fact the need for ‘Social Distancing’ by the space agency’s personnel
has seriously affected, if not actually brought to a halt the work on nearly
every NASA program.
This includes the final tests and preparations for the James Webb space telescope, which was due to be launched just a year from now in March of 2021. The space telescope itself is currently in California where it had been undergoing its final assembly and testing. However California’s governor has ordered that all ‘non-essential’ workers remain at home so the entire effort on NASA’s largest unmanned program has come to a complete halt. How much of a delay this will add to the already behind schedule launch of the Webb telescope is impossible to say at present.
Shortly after this last unfolding test of the main mirror of the James Webb Space Telescope all work was halted due to the threat of Covid-19. (Credit: Space News)
However there are other programs that simply cannot be put on hold for one reason or another. The new Mars rover, recently given the name ‘Perseverance’ is perhaps the best example of this. You see the spacecraft’s launch window, the period of time when Mars is in the right position relative to Earth in the Solar system for a spacecraft to reach it, is only open during July and August of this year. If Perseverance doesn’t launch during that time frame then the mission will have to be delayed for a full 26 months until the next window opens in late 2022.
Technicians in Florida working on the Perseverance Mars rover can’t stop work. The rover has to launch in July or August! (Credit: CNN.com)
Because
of that hard deadline NASA personnel are working around the clock on the final
preparations for the spacecraft’s launch. Fortunately Perseverance has already
been delivered to Cape Kennedy and is now undergoing prelaunch assembly but
there’s still a considerable amount of work remaining. And even with the threat
of a covid-19 shutdown looming over their work the technicians at Kennedy still
have to do a meticulous, almost perfect job, anything less could compromise the
success of the entire mission.
Part of the preparations for Perseverance’s launch included the last test here on Earth of the little drone helicopter that will accompany Perseverance down to the Martian surface. Before being packed into the rover vehicle for its long trip the helicopter’s two rotor blades were spun at 50 RPM on a test stand, the last time they will spin before they do so in the thin Martian atmosphere. While the helicopter is not considered an integral part of the Perseverance mission, officially it is referred to as a technology demonstration, if successful the little drone will take the first flight of any manmade object on another planet.
Final test of the little Helicopter that will travel to Mars aboard the Perseverance Rover. It’s now got to be packed up and made ready to go! (Credit: NASA JPL)
Another mission that could be delayed because of Covid-19 is Space X’s long anticipated first manned mission to the International Space Station (ISS). It was only a few weeks ago that Space X announced that this long awaited first manned mission of their Dragon capsule would take place the second week of May. That time frame however could very well put the mission right at the peak of the pandemic in Florida! Since this first mission of NASA’s commercial crew program is already more than two years behind schedule perhaps the wisest course at present would be to just delay the mission until well after the pandemic has run its course, until September or even later.
An unmanned Space X crew Dragon docking at the ISS. The first manned mission is scheduled for May but will Covid-19 cause a delay? (Credit: Space News)
Speaking of the ISS, what happens to the astronauts who are aboard the station if Cape Kennedy has to be shut down because of the pandemic? While the astronauts themselves may be safe from Covid-19 their supply chain is definitely threatened by the situation here on Earth. All of the countries that are capable of resupplying the ISS are dealing with severe coronavirus outbreaks that may limit their ability to launch unmanned supply ships.
The Crew aboard the ISS may be safe from any viruses but what about their supply link with Earth? (Credit: NASA)
No doubt if the supply situation on the ISS should become critical then either the US or Russia would certainly, and ‘carefully’ assemble a resupply mission, but what if that launch should fail? In any case there is certainly a great risk that the normal operations of the ISS will be curtailed because of the virus.
The expedition 63 crew to the ISS was just launched from Russia after a prolonged quarantine period to make certain they weren’t infected with Covid-19 (Credit: NASA)
All
of this is just another sign of how much the coronavirus outbreak is now
dominating almost every aspect of human life, and not just here on Earth.
As
you know the science of paleontology is about origins, where did life on this
planet come from and how did it find its wandering way to us? Well the big
story this month fills in a rather large piece to that puzzle. Fossil hunters
in Australia think that they may have discovered evidence of the first animal!
As you may guess the first animal evolved during the time of the very first multi-cellular life, a period now known as the Ediacaran period some 550 to 570 million years ago, see my posts of 16June2018, 15August2018 and 22January2020. Fossils of creatures from the Ediacaran were first unearthed back in 1946 but even from the beginning evolutionary biologists had problems connecting them to later, better understood groups of animals.
The Ediacaran creature Dickinsonia costata. Is that an animal, plant or what? (Credit: Wikipedia)
In fact analysis of the Ediacaran fossils indicates that these creatures were constructed in a manner totally unlike that of any life form that exists today. One example of this is the complete lack of anything resembling a mouth, anus or digestive tract in the Ediacaran fossils leaving scientists to wonder how the creatures consumed their food and excreted their waste.
Artists illustration of life during the Ediacaran period. Very different from the animal life of today! (Credit: Science Photo Library)
Additionally
the very body shape of the Ediacaran fauna is strange, paleontologists often
describing them as having a ‘quilted’ pattern, something like an air mattress.
Another way in which the Ediacaran creatures differ from all modern animals is
that, although at first glance they may appear to possess right-left symmetry a
closer inspection reveals that in fact they are not bilaterally symmetric.
Bilateral symmetry is one of the cardinal features that connects all modern animals together. While it is true that individuals are rarely right-left mirror images, you may have a small mole on your right cheek for example. In general however people have as many moles on their left sides as their right. As a species we, and other animals are strongly bilaterally symmetric.
Bilateral Symmetry is a defining factor amongst almost all living animals. (Credit: Study.com)
Looking at the image below of a member of the Ediacaran genus Dickinsonia you might say that the creature’s segments are also bilaterally symmetric. However, taking a look at the second figure below, which is a blowup of the area where the right and left segments come together, we can see that the segments are actually offset from each other in a fashion known to mathematicians as glide reflection.
Dickinsonia and how it grew! Not like any animal alive today! (Credit: Wikipedia)
Closeup of the center line of Dickinsonia. Notice how the segments do not match up but are offset from each other. This pattern is called glide reflection and is unlike anything alive today! (Credit: Wikipedia)
Glide reflection shows up in a number of Ediacaran creatures such as Spriggina, Andiva and Yorgia. For glide reflection to be so prevalent among the Ediacaran creatures is also a clear sign that the manner in which they grew must have been very different from the way modern animals grow.
A fossil of Andiva ivantsovi. It’s little wonder that paleontologists have problems trying to connect creatures like this with our modern forms. (Credit: Wikipedia)
So
if the best known fossil creatures from 550 to 570 million years ago were not
related to modern animals then where was our ancestor? Well in a paper
published in the Proceedings of the National Academy of Science (PNAS)
Professor Mary Droser and lead author Scott Evans, a recent Doctoral graduate,
both from the University of California Riverside claim to have found crucial
evidence of our early ancestor in rocks from the original Ediacaran region of
southern Australia. Recognizing that the first animal would certainly lack hard
parts that could fossilize easily, otherwise it would have been discovered by
now, they searched for small impressions in the rocks that might remain after
the creature had died and decayed.
What they found were numerous rice grain sized depressions, 2 to7 millimeters in length and 1 and 2.5 in width, that showed hardly any clear indication of what the creature that made them looked like. Modern technology to the rescue however as the researchers used 3D laser scanning to precisely measure the outlines of the depressions. Based on those measurements the creature that made the depressions was basically tube shaped, bilateral, and was thicker at one end, presumably the front. In other words it was basically built like us. It was an animal. See image below.
Those little depressions inside the chalk square are all that remain of the first animal. (Credit: Albany Herald)
Result of Laser scan of an impression left by Ikaria wariootia. (Credit: Geology Page)
The paleontologists gave their new species the name Ikaria wariootia where Ikara means ‘meeting place’ in the local Adnyamathanha language and Warioota is the name of a creek that runs through the Ediacaran region. The laser measurements were so precise that Evans and Droser could even make out the faint body curves made by I wariootia’s muscles which bore a distinct resemblance to those of a modern earthworm indicating both how the creature moved as well as its mode of life.
Artists impression of Ikaria warioota. (Credit: University of California Riverside)
According
to Doctor Droser. “This is what evolutionary biologists predicted. It’s
really exciting that what we have found lines up so neatly with their
prediction.”
The
evidence is growing that the best known creatures from the Ediacaran period,
Spriggina, Dickinsonia and their relatives, were evolutionary dead ends leaving
no descendents in our modern world. Instead the future belonged to little
worm-like Ikaria wariootia, and millions of years later to us.
With
the coronavirus dominating all of the news going on in the world today I
thought it might be a good idea today to have a more lighthearted post for a
change.
We’re all familiar with coffee rings, the way a bit of spilled coffee or wine will dry to produce a hard, dark line around it’s edge while the center is relatively much paler. See images below.
A typical coffee ring. Notice how the edges form nice dark lines outlining the original area of the stain. (Credit: Inspiration Hut Marketplace)Not all coffee ‘rings’ have to have a nice circular shape however. Again the dark edges clearly enclose a much lighter interior of the stain. (Credit: Wikipedia)
The cause for this phenomenon is a combination of two factors. The first factor is that evaporation of the spilled liquid occurs more rapidly at the edges simply because there is more surface area exposed to the air. Because the edges evaporate faster you would think that the area of a spill would get smaller as it dries but it doesn’t and that’s because of the second factor, capillary action.
A droplet of clear water on a surface. The roundness of the drop along its edges gives it a greater surface area there leading to greater evaporation. (Credit: Buggy and Buddy)
Instead of the evaporation around the edges causing the area of the droplet to shrink in size water flows from the center to the edges. (Credit: Robert D. Deegan et al)
Remember back in your High School Chemistry class when your teacher showed you the way water in a thin glass tube seems to try to climb up the sides of the tube, that was capillary action. Capillary action happens because of the fact that water molecules are more strongly attracted to molecules of other substances than they are to other water molecules. In the case of the glass tube the water molecules are attracted to the glass walls of the tube rather than other water molecules so they literally climb up the walls, forming what is known as a meniscus. See images below.
In a glass tube water molecules are more strongly attracted to the glass molecules than to each other. This generates capillary action as the water seems to try to climb the walls of the tube. (Credit: USGS.gov)
In
a spill, the water molecules are more strongly attracted to the surface they
are resting on than other water molecules so even though the edges are
evaporating faster the area of the spill remains the same. In order to keep the
area the same water flows from the center of the spill to the edges and any
larger, darker molecules, like coffee, that are dissolved in the water are
carried toward the edges by that flow. As the spill continues to evaporate more
and more of the larger molecules are pushed toward the edges to be deposited
and left there as the familiar ring once the water is completely gone.
The
coffee ring effect can be a problem in some technologies that require an even
deposition of a chemical across a surface, such as in printed electronics.
Chemists studying the phenomenon have found that adding chemicals known as
surfactants, that’s soap to you and me, can reduce the effect.
In an interesting twist on the subject, Stuart Williams, a Professor of Mechanical Engineering at the University of Louisville in Kentucky has been studying the patterns left behind after the evaporation of one of his state’s best known products, Bourbon Whiskey. What Professor Williams has found is that under controlled labouratory conditions instead of forming rings at their edges American whiskeys, and only American Whiskeys, form spider web type patterns. Not only that but each brand of American whiskey has its own unique pattern, a pattern so distinctive that it might be possible to use the technique to identify counterfeit whiskeys. See images below.
A sample of the spidery webs formed by different brands of whiskey. (Credit: Ars Technica)
Now I said that Professor Williams studied the phenomenon under labouratory conditions and that requires a little explanation because you see alcohol is another chemical that inhibits the formation of coffee rings. Too much alcohol, more than 30% and you’ll only get a uniform coating, no pattern of any kind. At the other end of the scale, too little alcohol and you only get the normal coffee ring effect at the edges. Only when the alcohol content was between 20-25%, or 40 to 50 proof, did Professor Williams obtain his spidery patterns. That means the doctor had to dilute his whiskey samples a bit, a horrible thought but remember this was all in the interest of science!
Doctor Williams in his labouratory. To his left you can see some of his test subjects. Nice work if you can get it! (Credit: Ars Technica)
In his lab Williams tested 66 different
brands of American whiskey, 56 bourbons and 10 from outside Kentucky along with
13 foreign whiskeys ( I don’t know how many were from Scotland or Ireland). To
date only one of the American brands has failed to produce a web like pattern
while none of the foreign brands has formed a web.
As
for what could be causing the difference between the American and foreign
whiskeys Williams says, “We believe that the increased solids extracted
from American whiskeys is responsible for these patterns. The chemicals
originate in the fermentation and distillation, but really undergo dramatic
changes during maturation.”
Once again each different brand of American forms its own unique spidery pattern. With this in mind Professor Williams is taking numerous samples of each brand and averaging the results in an effort to build up a library of brand patterns. Williams hopes that the whiskey industry will be able to use this library both for quality control as well as spotting counterfeit products.
To be considered a true bourbon a whiskey must be distilled in Bourbon County Kentucky. That’s what makes counterfeiting profitable. (Credit: World Map)
It’s
amusing to think that something as familiar and innocuous as coffee rings may
wind up as a way to identify top shelf bourbons. At least I hope it got your
mind off of covid-19 for a few minutes!
There have been some very interesting engineering developments in both robotics and artificial intelligence (AI) recently. These new designs clearly show what I consider to be the main theme of these subjects, a convergence of the artificial and organic as engineers learn how to copy the abilities of living creatures, taking advantage of the strengths of biological systems in order to improve the functioning of their designs.
Learning how to use the abilities of organic life in mechanical systems is about more than just making a robotic copy of ourselves. (Credit: YouTube)
We are all aware of how awkward and clumsy the movements of robots appear when compared to the grace and dexterity of living creatures. The mechanical walk of a robot as depicted in SF movies of the 50s and 60s may be a cliché, but nevertheless it’s still pretty much true. Because of this inflexibility robots are usually designed for a single, repetitive task. Multi-tasking for robots is usually just out of the question.
A Robot from the 1039 World’s Fair in New York City. He looks like he could hardly move! (Credit:History.com)
With that in mind I’ll start today’s post by describing some of the work of Doctor Fumiya Iida of the Department of Engineering at the University of Cambridge in the UK. Throughout his 20-year career Dr. Iida has studied the anatomy of living creatures in an effort to improve the agility of his own robotic creations.
Doctor Fumiya Iida with some of his work. (Credit: Phil Mynott)Doctor Lida’s robotic hand for playing the piano. (Credit: Linked In)
Dr. Iida has found inspiration from a wide range of different anatomical structures. Everything from the prehensile tail of a monkey to the sucker mouth of a leech can become for him a new way for a robot to move and manipulate objects. Dr. Iida and his colleagues refer to this program as ‘Bio Inspired Robotics’. Dr. Iida’s latest success has been the demonstration of a robot that can perform a labourious and backbreaking job that before now could only be accomplished by humans, picking lettuce.
Picking lettuce is extremely labour intensive. Automating this, and other vegetable harvesting would eliminate a great deal of low paid, hard labour. (Credit: Flickr)
Now
at first you might think that picking lettuce would be an easy job to design a
robot to handle. After all lettuce heads are all planted evenly spaced in
straight rows. All a robotic picker has to do is go along the rows and grab the
lettuce heads.
It’s
not that simple, first of all a lettuce head is fairly soft and every
individual head of lettuce is a somewhat different size and shape. This makes
picking the lettuce heads difficult for most robots, resulting in a
considerable amount of damage to the lettuce. Also, the outermost leafs of a
lettuce head are generally so dirty or damaged that they have to be removed, a
task that hitherto no robot has been able to carry out reliably.
Putting all that he’s learned into the problem Dr. Iida utilized a combination of visual sensors, soft grippers and a pneumatically activated knife for his robot picker. First the robot uses its cameras to locate a lettuce head before positioning itself directly above it. Then lowering itself onto the lettuce the robot pushes the unwanted leaves down and out of the way before cutting the head at its base. The robot’s soft grippers then lift the head up and place it in a basket.
Procedure used by Doctor Iida’s robot lettuce picker. (Credit: Wiley Online Library)The lettuce picking robot in action. (Credit: The Robot Report)
So far Dr. Iida’s robot has been able to achieve an 88% harvest success rate, good but it still needs improvement before it can replace human pickers. Nevertheless when perfected this technology could be adapted to other types of produce, finally automating what has remained one of the hardest and lowest paying of all jobs.
So,
if engineers are starting to construct robots to harvest our vegetables for us,
what other boring repetitive jobs can they be built to take off our hands? Well
researchers at the Massachusetts Institute of Technology (MIT) are actually
developing robots that can learn to do common household chores like setting the
table by watching us do it!
The technology has been given the name ‘Planning with Uncertain Specifications’ or PUnS and the idea is to enable robots to perform human like planning based on observations rather than simply carrying out a list of instructions. By watching humans completing a task, like setting a table, the robot learns the goal of the task and a general idea of how to accomplish that goal. Known as ‘Linear Temporal Logic’ or LTL these computer generated formulas serve as templates for the robot to follow in order to accomplish its goal.
Robotic Vacuum clears are a simple example of PUnS. Whenever they bump up against an obstacle they just make a turn and head off in a different direction. Eventually they will clean the entire floor! (Credit: The New York Times)
In the study the PUnS robot observed 40 humans carry out the task of setting a table and from those observations generated 25 LTL formulas for how to complete the task. At the same time the computer assigned to each formula a different confidence of success value. Starting with the highest value formula the robot was then ordered to attempt to complete the task and based on its performance it is either rewarded or punished.
A Robotic arm that has learned, not be programmed to set a table! (Credit: YouTube)
In a series of 20,000 tests starting with different initial conditions the robot only made a mistake 6 times. In one test for example, the fork is hidden at the start of a test. Despite not having all of the items required to completely set the table the robot went ahead and set the rest of the dinnerware correctly. Then, when the fork was reveled the robot picked it up and placed it in the correct position, completing the task. This degree of flexibility in an automated system is unprecedented and points the way to robots learning how to accomplish different jobs not by mindlessly following a long list of instructions, in other words a program, but rather the same way humans do, by watching someone else do it. So, robots are now being designed to move more like a living creature does, and computers are being programmed to learn more like a human does. It took evolution billions of years to give living creatures those abilities but by observing and copying biological systems our robots and computers are quickly catching up. Who knows where they’ll be in another few decades.
With the Covid-19 virus spreading around the world it’s critical that we study the lessons learned from past pandemics if we are to have any hope of minimizing the loss of life than now threatens our society. Since this is as much history as medical science I decided that for this post I would ask my brother Tom, a history teacher at Mastbaum High School here in Philadelphia for his help in telling the story of the Spanish Flu pandemic of 1918.
At the beginning of the year 1918 the world was fully engulfed in the First World War. After three years of conflict the continent of Europe had become nothing more than a single large battlefield. Then, in January of that year a new player entered the war, Influenza. Ironically, the influenza pandemic of 1918 has since become known historically as the Spanish flu because, since Spain was a neutral in the World War, they were the only country that would honestly report the large numbers of the sick and dead that were caused by the disease.
The horrible conditions in the trenches that millions of soldiers lived in during World War 1 were perfect breeding grounds for many diseases. (Credit: Britannica)
To
this day scientists are still not precisely certain where the outbreak started.
There is evidence that it may have started at a field hospital outside the
French lines. Or it could have begun in an US Army training camp in Kansas. No
matter where it began by the end of the pandemic an estimated 17 to 50 million
people had died worldwide. Now influenza is of course the flu, a disease that
we are all familiar with. This particular strain of the flu however was a flu
like no other however as it struck down the strong and youthful as well as the
old and the very young who are the usual victims of the flu.
The French field hospital that is considered by many to be the original source of the disease was overcrowded and plagued by sanitation problems. Food for the hospital’s patients came from livestock that were kept behind the hospital, much too close to the large number sick and injured soldiers. Many scientists are of the opinion that the disease began in a flock of chickens that were being kept for food behind the hospital. The bird’s droppings passed the infection to some pigs that were also being kept as food before leaping into human hosts.
A French Field Hospital early in the war, caption says 1914. I doubt it stayed this nice a clean for very long! (Credit: Flickr)One of the greatest success stories in human history is our domestication of other animals. This carries a downside with it however as animal diseases can more easily pass into human populations. (Credit: Center for Disease Control)
Those soldiers who recovered at the field hospital then carried the flu with them back to the trenches when they returned to their units, passing the illness on to their comrades. Before long a few of the sick French soldiers were captured by the Germans, in the process passing the disease on to them. Soldiers on both sides who were given leave then took the infection back to the cities and towns of their countries spreading the disease ever further.
In the United States the first recognized case of the flu was Albert Gitchell, an Army cook at Ft. Riley, Kansas. As a cook Gitchell’s job was to feed the recruits and as he did so he unknowingly passed the disease on to hundreds. Those recruits who completed their training were shipped to Queens New York to wait for a ship to transport them to the battlefields in France. City officials in New York were slow to recognize the danger of so many sick soldiers in their midst and soon the infection was spreading throughout the city and on to the other cities of America.
Some of the sick soldiers at Fort Riley in Kansas. All of this started with one infected man! (Credit: Wikipedia)
In
fact politicians and civil servants throughout the world were slow to react to
the pandemic. Partly this was due to their preoccupation with the requirements
of conducting the war, especially the need for secrecy. In addition however
governments throughout history just never seem to be able to recognize the
dangers of a health or environmental crisis until they have grown into a huge
disaster.
The politicians in 1918 treated this new flu as if it were hardly different from the flu of other years. They considered it to be no more than a temporary nuisance and felt little urgency in either treating the victims or stopping the spread of the disease. More than anything else governments are concerned about a panic starting amongst their people so they always tend to try to hide really bad news.
Eventually however the growing number of the sick and dead became so large that even the politicians had to take action. In many cities activities that involved large crowds were limited in size or even called off. For a short time church services were held in the outdoors in an attempt to reduce the spread of the virus but it wasn’t long before such gatherings were being cancelled entirely. As the crisis worsened Police began to wear surgical masks in an effort to protect themselves, schools were closed and cities like New York and Boston began to resemble ghost towns as people remained in their homes.
Eventually the public health services in many cities did react, as here in Evanston Illinois. (Credit: Evanston Now)A public service announce of the time. Much as today our public leaders considered the flu to be an interference to the issues they considered important! (Credit: History of Vaccines)
Philadelphia
was one city that seemed to have escaped the worse of the epidemic. In the
early part of September 1918 there had been a small number of cases of the flu
at local hospitals but few deaths.
As
a part of the Victory Loan Program to benefit the war effort the city fathers
of Philadelphia were planning what they knew would be the biggest parade in the
city’s history. The city’s health commissioner had been advised by the health
commissioners of New York and Washington to cancel the parade but he owed his
job to the local party bosses and so under pressure from the politicians he
allowed the parade to go on as scheduled on the 28th of September 1918.
On that day the citizens of Philadelphia lined Broad Street in the thousands, creating an enormous crowd that pressed against each other, the perfect breeding ground for any infectious disease. Within days the flu had spread throughout the city and the death rate soon rose beyond that other the those of Boston or New York.
Philadelphia’s Liberty Bond Victory parade in 1918. What you can’t see here is the Spanish Flu virus spreading from one person to another! (Credit: Smithsonian Magazine)
In contrast the city officials in St. Louis listened to the warnings of their health officials and cancelled their Victory Bond parade. Thanks to the wisdom of their leaders the city of St. Louis escaped the worst of the plague. The chart below dramatically illustrates the consequences of each city’s leaders response to the threat posed by the flu.
Comparison of the Death Rates caused by the Spanish Flu in Philadelphia (Solid Line) and St. Louis (Dotted Line). The benefit of St. Louis canceling its parade is easy to see. (Credit: Quartz)
The
influenza pandemic of 1918 affected every corner of the world and remained a
deadly problem until it finally died out around December of 1920. The precise
death toll caused by the Spanish Flu will never be known for certain but many
scientists believe that it was greater than the number of those who perished in
the actual war. In many cities throughout the world the dead were so numerous
that they were buried in mass graves.
In
the hundred years since 1918 the United States has not witnessed a health
emergency anywhere near the scale of the Spanish flu, until now. If we are to
fight the Covid-19 pandemic then we are going to have to learn the lessons of
the past, a task that so far we are not accomplishing very well. The policies
of our governments must be solidly based on medical science, not on hunches or
wishful thinking. We must demand that our leaders act with the sole goal of
saving as many lives as possible, ignoring all considerations of winning
elections or protecting the economy. Covid-19 is going to be a test of not only
of how much we’ve learned about fighting infectious diseases, but also about
whether or not we have the wisdom to act on the lessons we’ve learned.
Regular readers of this blog will know that there are two subjects that I find very interesting, astronomy and paleontology. Well here’s a post that connects those very different studies, showing how everything in the Universe is linked in ways that we can hardly imagine.
We’re all familiar with the tides, that rising and lowering of the waters of the oceans that happens about twice a day. And we all know that somehow those tides are connected with the Moon, that the highest tides occur during the time of the full Moon and that it’s the Moon’s gravity that somehow causes the tides.
At low tide in many places you can go out on the exposed rocks and observe all of the different types of sea life! (Credit: Visit Santa Cruz County)
All of that is true, not only does the Earth’s gravity pull on the Moon, causing it to orbit our planet but the Moon also pulls on the Earth. Because of this what actually happens is that both bodies orbit around the center of gravity of the Earth-Moon system but because the Earth is much more massive than the Moon that center of gravity is much, much closer to the Earth than it is to the Moon, in fact it is inside the Earth!
The center of Gravity of the Earth-Moon system is inside the Earth but not at our planet’s center! (Credit: Quora)
Most people also know that an orbit between two astronomical objects represents a balance between the pull of gravity and the push of centripetal force. The fact is however that only the center of the two objects exactly follows the path of the orbit. For that portion of the Earth that is closer to the Moon than the center is, gravity is stronger than centripetal force so that portion is pulled toward the Moon. On the opposite side of the Earth, that part further from the Moon than the center, centripetal force is stronger so that it is pulled away from the Moon. This is the reason why there are two tides every day, the one pulled toward the Moon by gravity and the one pushed away by centripetal force.
There are two tides every day. One towards the Moon and one away from her. (Credit: The Conversation)
These tidal forces are also the reason why the Moon only shows one face toward the Earth. Over billions of years the effect of tides is to slow the rotational motion of an astronomical object until finally it keeps the same face towards the other object it orbits. Since the Moon is much smaller and less massive than the Earth it began with a much smaller angular momentum, all of which is now gone leaving our Moon eternally showing us the same face.
The Moon does rotate once every orbit! That way it always keeps the same face towards us! (Credit: PBS)
You
might wonder if the same thing could happen to the Earth, is the crashing of
the tides against the land masses of the Earth twice a day slowing down our
planet’s rotation? Will our planet at some time in the future stop rotating so
that it will always keeps the same face towards the Moon? Yes, it point of fact
it will. Astronomers have actually measured the slowing down of the Earth’s
rotation, the lengthening of the day.
And if you think about it that means that in the distant past the length of a day must have been shorter than it is now. That would also mean that there would have been more days in a year than the 365 & 1/4 that we have today. Trying to prove this is where paleontology comes into play because fossil hunters have 200 years of experience in studying the evidence of the past.
For example, we all know how tree rings record the annual growth of a tree. Not only can scientists determine the age that a tree was when it died by counting the number of a tree’s rings but they can also tell during which years the tree grew well and in which it grew poorly by comparing the width of the different rings. And it doesn’t matter whether the tree has been freshly cut down, or died millions of years ago. If well preserved petrified wood still has its tree rings.
We all know about tree rings but did you know that tree rings can still be preserved after millions of years? These rings can tell paleontologists a lot about the environment millions of years ago! (Credit: The American Southwest)
Other types of living creature are also known to have regular, visible growth rings, some of which record the passing of each day rather than each year. One such type of animal is the familiar clam whose shell grows a little bit every day. More than that however, like most creatures clams usually grow less during the winter, making those daily rings narrower and even a little bit darker during the winter months. This allows paleontologists to count the number of days in a year simply by examining the growth rings of an ancient clamshell.
The growth rings in this modern clam record the daily environmental conditions in the location where it lived! (Credit: 4.files.edl.io)
Of course you need an exquisitely preserved fossil and paleontologist Niels de Winter of Vrije Universiteit in Brussels Belgium has one that fits the bill. The 70 million year specimen of Torreites sanchezi is a member of a group of bivalves known as rudists that went extinct at the same time as the dinosaurs.
Two (?) specimens of T sanchezi. (Credit: Curiosmos)
T sanchezi also grew large, making it that much easier to count each individual ring, and Doctor de Winter’s specimen lived a full seven years giving him plenty of data to work with. What de Winter found was that 70 million years ago there were 372 days in a year and therefore each day was about a half an hour shorter. Back then there were only 23.5 hours in a day, just as the astronomers predicted.
Growth rings from T sanchezi measured by Doctor de Winter. (Credit: Civilsdaily)
Finally,
if the Earth’s rotation is slowing down that spin has to go somewhere,
conservation of angular momentum is one of the most thoroughly tested of all
physical laws. In fact Earth’s spin isn’t disappearing, it’s going to the Moon.
That’s right the slowing down of the Earth’s rotation is causing the distance
to our Moon to slowly increase.
We know that is happening because we have measured it. Back during the Apollo Moon program our astronauts set up science packages on the Moon and one of the pieces of equipment they left behind were laser reflectors. Ever since 1969 astronomers have used telescopes to send laser pulses to the Moon and detect the returns off of those reflectors. In this way astronomers can measure the distance to the Moon with fantastic accuracy and over the last 50 years they have measured a steady 3.82 centimeter increase in the Earth-Moon separation every year.
The Laser Reflector left on the Moon by Apollo 11. Five such reflectors were left by the astronauts! (Credit: SpaceRef)There are astronomers who regularly use those reflectors to measure the distance to the Moon with fantastic precision! If you think about it, what better evidence could you have that the Moon landings actually took place!!!!! (Credit:Aviation Stack Exchange)
It all ties together, Newton’s theory of gravity explained where the tides came from. Those same laws indicated that the tides would cause the Earth’s rotation to slow, something that paleontology has confirmed. That slowing causes the Moon to slowly move away from our planet, something our space program has confirmed! That’s the beauty of science, it all connects up, it all fits together and supports itself.
Between the years 1650 and 1900 the science of Physics made tremendous progress in understanding how the world and the things in it worked. Building on the mathematical framework provided by Galileo and Newton the phenomenon of kinematics, celestial mechanics, thermodynamics, and electromagnetism were studied and described. It seemed to many as if there was no problem that Newtonian Physics could not conquer. Indeed there were actually some physicists in the late 1800s who believed that they were within reach of a complete understanding of the Universe.
Newton’s famous quote concerning the debt he felt he owed to Galileo and Kepler. Together these three established the rules and formulation of what became ‘Classical Physics’. (Credit: Pinterest)
That comfortable idea blew up between 1900 and 1930 as the twin revolutions of Relativity and Quantum Mechanics completely changed our view of reality forever. These new ways of looking at the universe were so exciting that they made the old, ‘classical physics’ of Sir Isaac seem more than a little tired. I must admit that when I started college in the 1970s classical physics was thought of as something you learned so you could understand the ‘good stuff’.
Classical Physics still works very well for large objects moving at slow speeds. The world of the small or the fast belongs to Quantum Mechanics and Relativity. (Credit: PPT)
That attitude has changed somewhat over the last 20-30 years as new instruments and new mathematical techniques have allowed physicists to take a look back at some old problems that 19th century physicists had ‘kinda, sorta figured out’ but never precisely understood. In general these problems dealt with systems of a large numbers of objects interacting in such complex manners that precise observations were nearly impossible while theoretical calculations involved so much ‘number crunching’ that no human being could ever perform them.
The latest supercomputer are allowing today’s physicists to analyze problems so complex that no human could ever do all of the arithmetic. (Credit: One Zero Medium)
Two of the new tools that are helping to overcome these difficulties are the development of computers and supercomputers along with high speed, high definition cameras. The computers have allowed physicists to perform calculations of extremely complex problems with thousands or even millions of variables, problems where simply the number of calculations to be performed are beyond human ability. The high speed cameras meanwhile allow the scientists to check, with ever greater precision, exactly what is happening in an experiment instant by instant, seeing things that the human eye could never catch.
Ultra High Speed Cameras are allowing scientists to see the details in phenomenon that happen too quickly for the human eye to observe. (Credit: CN Rood)
One phenomenon that in classical physics was understood in general terms but not in its details is turbulence. We are all familiar with turbulence, whether it be strong winds whipping around chaotically or white water in a fast, rocky stream and while it may seem as if it is nothing more than a slight annoyance, turbulence is actually a big problem affecting the design of ships and aircraft as well as forecasting the weather.
Turbulence is a problem of great concern in the aviation industry. (Credit: YouTube)
Strictly
speaking turbulence is when the flow of a fluid is caused to break up into
swirling vortexes, then those vortexes interact with each other forming an ever
growing number of smaller vortexes until the result is just a chaotic
maelstrom. This sort of behavior makes turbulence a perfect subject for the
‘new’ classical physics.
Scientists at Harvard’s John A. Paulson School of Engineering and Applied Science have constructed an especially designed chamber for the study of Turbulence. Contained within a water filled 75 gallon aquarium are two vortex ‘guns’ facing each other. The guns each fire a vortex ring, similar to a smoke ring, which collide in the aquarium’s center generating turbulence. See gif animation below.
Check this out. Even aside from the physics involved it’s just cool to watch! (Credit: Harvard University, John A. Paulson School of Engineering)
The water from each of the ‘guns’ is dyed a different colour and each collision is filmed with a high speed, HD camera taking thousands of images per second. What the researchers have observed is a Russian-doll like effect starting with the two main vortexes forming antisymmetric waves at their edges as they collide. At the crests of these waves a number of finger-like filaments develop that counter rotate from their adjacent filament and form new, smaller vortexes. These new vortexes then interact with each other to begin the entire process all over on a much smaller but more numerous scale. With their equipment the scientists have been able to observe three complete sequences before the entire process disappears into chaos. These observations are then compared to the computer simulations developed by the theorists. See gif animation below.
Computer simulation of turbulence. Again it’s just beautiful to watch! (Credit: Harvard University, John A. Paulson School of Engineering)
This
back and forth checking between observation and mathematical model is slowly
teaching us more and more about the incredibly complex but still familiar
phenomenon of turbulence.
Another familiar phenomenon that is nevertheless still mysterious in many ways is the behavior of a water droplet as it collides with a flat surface. Such a collision has for many years been known to produce three entirely different results. Sometimes the droplet will simply spread out, smoothly covering the surface in a nice circular pattern. More often the droplet splats, that is spreads out explosively resulting in a very uneven pattern. Rarest of all is where the droplet can literally bounce back from the surface as if it where a ball of some kind.
High Speed images of a water droplet literally bouncing off of a surface. Time is in milliseconds ms. (Credit: Telegraph)
Scientists
at the University of Warwick are studying the process of water droplets
striking a surface and in a recent paper published in the journal Physical
Review Letters they have announced what they think is the underlying cause of
the three types of collision. After numerous computer simulations, which
they’ve compared to high-speed videos the researchers have concluded that the
critical factor is the speed of the water droplet.
Consider a water droplet that is slowly approaching a surface. The collision causes the droplet to deform and spread out. As the droplet spreads out intermolecular attractions known as van der Waals forces cause the water molecules to adhere to the surface. As the droplet spreads further the area of contact increases and the van der Waals forces cause the droplet to evenly coat the surface. At higher speed however some of the droplet will spread out but more will bounce back causing the droplet to break up, ejecting smaller droplets that then also strike the surface and generating the familiar splat pattern.
The familiar splat pattern that a water drop makes when it strikes a surface. (credit: Wikiwand)
If
the speed of the droplet is just right however a tiny layer of air forms
between the droplet and the surface. This layer will be no more than a few
nanometers (one nanometer is one billionth of a meter) in thickness but it can
act as a trampoline causing the entire droplet bounce off of the surface
without ever actually ever touching it. Only at the correct speed is the effect
possible, too slow and the van der Waals forces can grab the droplet while too
fast and the droplet pushes through the cushion of air striking the surface
violently.
While
the mechanics of water droplets might seem like an interesting subject with no
real importance it’s worth noting that the behavior of droplets is very
important in several technologies, everything from ink-drop printing to spray
painting. Like turbulence, the behavior of water droplets is just one of the
ways that classical physics is still being employed to better understand the
world around us.
