(Roughly) Daily

Posts Tagged ‘Physics

“In the landscape of extinction, precision is next to godliness”*…

There is a portion of the sky where no spacefarer wants to go. It causes Astronauts to see shooting stars in front of their eyes, sets off emergency sensors and renders satellites useless. This Bermuda Triangle of space isn’t just a cause for concern for our future of space exploration, it could be the sign of something far more deadly. This may herald an event that last happened 42,000 years ago, which wiped out our closest relative, the Neanderthals. Welcome to the terrifying world of the South Atlantic Anomaly.

In the 80s engineers noticed that most satellite errors happened over South America and the South Atlantic. These errors ranged from minor glitches, wiped data to full-blown crashed satellites. But they couldn’t quite pinpoint what was causing these troubling errors, they named this mysterious area the South Atlantic Anomaly (SAA).

We didn’t understand the dangers of this region for a long time. When the Hubble Space Telescope first turned on in 1990 they found that the computers kept crashing and data was corrupted almost every time it flew over the South Atlantic. Not wanting their billion-dollar telescope to crash to Earth, the engineers had no choice but to switch it off every time it passed over this deadly patch of sky, and still do today. Not ideal, but it saves the telescope from this mysteriously dangerous part of space.

So what makes the South Atlantic Anomaly so dangerous? It turns out it is all down to the Sun and a crack in Earths armour caused some very bizarre geophysics.

So what does struggling satellites means for us here on Earth? Well, quite a lot really. It could be a sign of something much more deadly, a geomagnetic reversal.

When we picture the Earth’s magnetic field we often think of it as unchanging. It is our eternal armour from deadly solar radiation as well as the guide for our sailors. Even some birds have evolved iron-rich cells in their eyes, enabling them to ‘see’ the magnetic field and navigate the globe. But the magnetic north pole hasn’t always been in the north.

The magnetic poles have flipped repeatedly over the millennia. The field weakens, disappears and then reappears in the opposite direction. We know this because iron-rich lava aligns to the magnetic field and then sets, so we can look at ancient rocks and see what direction magnetic north was when it formed.

We don’t have a complete understanding of how the magnetic field is generated and why it flips. We know that convection currents of iron-rich mantle create the field, but the interactions between these immense systems are complex and hidden from us. What’s more, there are no patterns to the past flipping events, so it is very hard to predict when one will happen.

But, models and simulations show that when the field gets weaker at the beginning of a magnetic flip, it seems to happen in a random area and then grows from there. The poles also start to drift quite dramatically and chaotically. This is worrying because not only does the South Atlantic Anomaly look like the weakening in a simulation, it is also growing, and the North pole is drifting further each year.

… So, it seems at least plausible that the South Atlantic Anomaly is the start of the next geomagnetic flip. If so, it could have enormous consequences for us!

The last time a flip happened was 42,000 years ago, but it was only a temporary event, and the poles returned to their previous locations, this is known as the Laschamps Excursion, and it lasted for about a thousand years. That meant Earth was without its essential protective shield for an awfully long time.

Now, 42,000 years ago is a significant time. This was when Neanderthals died out. We (Homo Sapiens) also started using caves, red ochre body paint, and the global craze of cave painting started. It was also when a lot of ice-age megafauna died out. All of which has been linked to the flipping of the poles during this period. This extinction event and Sapien revolution has been called the Adams Event (after Douglas Adams and the infamous 42).  

This theory suggests that when the poles flipped, the Earth had a thousand years without its protective layer, so the planet was bombarded with radiation. This depleted ozone, increased radiation on the surface, messed with weather patterns and caused abrupt climate change.

Scientist even suggests that this is why we suddenly took to living in caves and using red ochre. We had to hide from the deadly rays of the Sun, and if we ventured out, we needed a powerful suncream, like powdered red ochre. This is why red ochre hand paintings became so widespread around this time.

But these immense changes hit one species particularly hard. Neanderthals were likely red-headed, light-skinned and mostly dwelt in steppes (grassy plains) and woodlands. They probably got sunburnt a lot. Unlike Homo Sapiens, it seems as though Neanderthals didn’t use red ochre much at all! All of this means that cancers would have been a deadly problem for them.

To make all this even worse, the radiation increased the strength of electrical storms, changed the weather patterns and screwed up many ecosystems. So the food that the Neanderthals hunted my have been driven away or gone extinct. It seems Neanderthals died out because they starved to death while being baked by the Sun. Meanwhile, we Homo Sapiens hid from the Sun, used weird sunscreen and adapted to new foods…

These flipping events take hundreds or thousands of years to pass due to the amount of heavy magma that needs to shift to cause a flip (however it is hypothesised it could take as little as a month in extreme circumstances). So we aren’t in any danger of waking up to a new direction for North. But, over the next few decades or hundreds of years, we will see the South Atlantic Anomaly grow and potentially be joined by many other areas of weak magnetism. We may even see some local flips in a few hundred years.

So, it seems at least plausible that the South Atlantic Anomaly is the start of the next geomagnetic flip. If so, it could have enormous consequences for us!

The South Atlantic Anomaly: Earth’s deadly weakness: “Do Failing Satellites Foretell An Imminent Extinction?” From Will Lockett (@welockett).

* Samuel Beckett

###

As we search for true north, we might send charged birthday greetings to a man whose life work could be at risk if there’s a flip (or an intense solar storm), Elihu Thomson; he was born on this date in 1853. An engineer and inventor, he was instrumental in developing the practical applications of electricity, especially alternating current. He invented electric welding and other important advances in electric lighting and power (among his lifetime total of about 700 patents). Thomson was also a cofounder of the General Electric Company (in 1892, in a merger of his Thomson-Houston Electric Company with the Edison Company.

source

“Man tends to define in terms of the familiar. But the fundamental truths may not be familiar.”*…

Most of us probably do not need to think too hard to distinguish living things from the “non-living”. A human is alive; a rock is not. Easy!

Scientists and philosophers do not see things quite this clearly. They have spent millennia pondering what it is that makes something alive. Great minds from Aristotle to Carl Sagan have given it some thought – and they still have not come up with a definition that pleases everyone. In a very literal sense, we do not yet have a “meaning” for life.

If anything, the problem of defining life has become even more difficult over the last 100 years or so. Until the 19th Century one prevalent idea was that life is special thanks to the presence of an intangible soul or “vital spark”. This idea has now fallen out of favour in scientific circles. It has since been superseded by more scientific approaches. Nasa, for instance, has described life as “a self-sustaining chemical system capable of Darwinian evolution”.

But Nasa’s is just one of many attempts to pin down all life with a simple description. In fact, over 100 definitions of life have been proposed, with most focusing on a handful of key attributes such as replication and metabolism.

To make matters worse, different kinds of scientist have different ideas about what is truly necessary to define something as alive. While a chemist might say life boils down to certain molecules, a physicist might want to discuss thermodynamics…

A comparative survey of the definitions that currently exist concludes…

To properly define life, we might need to find some aliens.

The irony is that attempts to pin down a definition of life before we discover those aliens might actually make them more difficult to find. What a tragedy it would be if in the 2020s the new Mars rover trundles straight past a Martian, simply because it does not recognise it as being alive.

“The definition can actually hinder the search for novel life,” says [Carol] Cleland. “We need to get away from our current concept, so that we are open to discovering life as we don’t know it.”

It is surprisingly difficult to pin down the difference between living and non-living things: “There are over 100 definitions of ‘life’ and all are wrong.

* Carl Sagan

###

As we strive for beginner’s mind, we might send exploratory birthday greetings to John Theophilus Desaguliers; he was born on this date in 1683. A natural philosopher, clergyman, and engineer, he is best remembered as the experimental assistant to Isaac Newton, who went on to popularize Newton’s work in public lectures and publications. On the strength of that work, Desaguliers was elected to the Royal Society and ultimately became its curator.

In his own work he coined the terms conductor and insulator. He repeated and extended the work of Stephen Gray in electricity. He proposed a scheme for heating vessels such as salt-boilers by steam instead of fire. And he made inventions of his own (e.g., a planetarium), and material improvements to others’ machines, such as Thomas Savery’s steam engine (by adding a safety valve and using an internal water jet to condense the steam in the displacement chambers) and a ventilator at the House of Commons. 

source

“Electricity is really just organized lightning”*…

A diagram from Galvani’s De viribus electricitatis in motu musculari commentarius, 1791.

In Mary Shelley’s Frankenstein, written in 1818, the young Victor Frankenstein becomes obsessed with the idea that electricity is a kind of fluid that endows living things with their life force. This obsession leads to tragedy.

Shelley’s view of electricity was, in fact, not an uncommon perspective at the time: just a few decades earlier the Italian scientist Luigi Galvani had shown that a shock of static electricity applied to the legs of a dismembered frog would cause the legs to kick. Galvani concluded that there existed a kind of “animal electric fluid” that was responsible for the animation of living creatures.

In the two hundred years since Frankenstein our view of electricity has certainly evolved, as has our ability to generate and control electric currents. But do we really understand what we’re doing? Do we even know what electricity is?

Physicist Brian Skinner (@gravity_levity) explains “Here’s why we don’t understand what electricity is.”

Pair with “Bruno Latour, the Post-Truth Philosopher, Mounts a Defense of Science.”

* George Carlin

###

As we plug in, we might send really fast birthday greetings to Leon Cooper; he was born on this date in 1930. A physicist, he shared the Nobel Prize in 1972 (with John Bardeen and John Robert Schrieffer) for contributing the concept of Cooper electron pairs which forms the basis of the BCS (their initials) theory of superconductivity. He is also one of the the namesakes and co-developers of the BCM theory of synaptic plasticity.

He went on to become a cofounder and co-chairman of Nestor, Inc., a company that applies neural-network systems to complex applications. The company built computer-based adaptive pattern-recognition and risk-assessment systems that could, for example, accurately classify complex patterns in sonar, radar or imaging systems. He also founded and was director of Brown University’s Institute for Brain and Neural Systems, which develops cognitive pharmaceuticals and intelligent systems for electronics, automobiles and communications.

The character “Sheldon Cooper” in Big Bang Theory is partially named for Cooper.

source

“The picture itself is just the tip of the iceberg”*…

Your correspondent’s rendering of an iceberg

Icebergs are less dense than water, so they always float with about 10% of their mass above the water. But which way up? An iceberg wouldn’t float exactly like on this page in reality. Its three-dimensional distribution of mass and its relative density compared to the water are both significant factors that are only approximated here.

From Joshua Tauberer (@JoshData), a tool that will let you draw an iceberg and see how it will float: “Iceberger.”

For inspiration, see Frederic Edwin Church’s 19th century iceberg paintings.

Frederic Edwin Church, Drawing, Floating Iceberg, June or July 1859
Brush and oil, graphite on paperboard, 18.8 x 37.5 cm (7 3/8 x 14 3/4 in.)
Cooper Hewitt Smithsonian Design Museum

* Sebastiao Salgado

###

As we seek balance, we might note that today is International Polar Bear Day. an event celebrated each year on this date to raise awareness about the conservation status of the polar bear.

source

“Facts alone, no matter how numerous or verifiable, do not automatically arrange themselves into an intelligible, or truthful, picture of the world. It is the task of the human mind to invent a theoretical framework to account for them.”*…

PPPL physicist Hong Qin in front of images of planetary orbits and computer code

… or maybe not. A couple of decades ago, your correspondent came across a short book that aimed to explain how we think know what we think know, Truth– a history and guide of the perplexed, by Felipe Fernández-Armesto (then, a professor of history at Oxford; now, at Notre Dame)…

According to Fernández-Armesto, people throughout history have sought to get at the truth in one or more of four basic ways. The first is through feeling. Truth is a tangible entity. The third-century B.C. Chinese sage Chuang Tzu stated, ”The universe is one.” Others described the universe as a unity of opposites. To the fifth-century B.C. Greek philosopher Heraclitus, the cosmos is a tension like that of the bow or the lyre. The notion of chaos comes along only later, together with uncomfortable concepts like infinity.

Then there is authoritarianism, ”the truth you are told.” Divinities can tell us what is wanted, if only we can discover how to hear them. The ancient Greeks believed that Apollo would speak through the mouth of an old peasant woman in a room filled with the smoke of bay leaves; traditionalist Azande in the Nilotic Sudan depend on the response of poisoned chickens. People consult sacred books, or watch for apparitions. Others look inside themselves, for truths that were imprinted in their minds before they were born or buried in their subconscious minds.

Reasoning is the third way Fernández-Armesto cites. Since knowledge attained by divination or introspection is subject to misinterpretation, eventually people return to the use of reason, which helped thinkers like Chuang Tzu and Heraclitus describe the universe. Logical analysis was used in China and Egypt long before it was discovered in Greece and in India. If the Greeks are mistakenly credited with the invention of rational thinking, it is because of the effective ways they wrote about it. Plato illustrated his dialogues with memorable myths and brilliant metaphors. Truth, as he saw it, could be discovered only by abstract reasoning, without reliance on sense perception or observation of outside phenomena. Rather, he sought to excavate it from the recesses of the mind. The word for truth in Greek, aletheia, means ”what is not forgotten.”

Plato’s pupil Aristotle developed the techniques of logical analysis that still enable us to get at the knowledge hidden within us. He examined propositions by stating possible contradictions and developed the syllogism, a method of proof based on stated premises. His methods of reasoning have influenced independent thinkers ever since. Logicians developed a system of notation, free from the associations of language, that comes close to being a kind of mathematics. The uses of pure reason have had a particular appeal to lovers of force, and have flourished in times of absolutism like the 17th and 18th centuries.

Finally, there is sense perception. Unlike his teacher, Plato, and many of Plato’s followers, Aristotle realized that pure logic had its limits. He began with study of the natural world and used evidence gained from experience or experimentation to support his arguments. Ever since, as Fernández-Armesto puts it, science and sense have kept time together, like voices in a duet that sing different tunes. The combination of theoretical and practical gave Western thinkers an edge over purer reasoning schemes in India and China.

The scientific revolution began when European thinkers broke free from religious authoritarianism and stopped regarding this earth as the center of the universe. They used mathematics along with experimentation and reasoning and developed mechanical tools like the telescope. Fernández-Armesto’s favorite example of their empirical spirit is the grueling Arctic expedition in 1736 in which the French scientist Pierre Moreau de Maupertuis determined (rightly) that the earth was not round like a ball but rather an oblate spheroid…

source

One of Fernández-Armesto most basic points is that our capacity to apprehend “the truth”– to “know”– has developed throughout history. And history’s not over. So, your correspondent wondered, mightn’t there emerge a fifth source of truth, one rooted in the assessment of vast, ever-more-complete data maps of reality– a fifth way of knowing?

Well, those days may be upon us…

A novel computer algorithm, or set of rules, that accurately predicts the orbits of planets in the solar system could be adapted to better predict and control the behavior of the plasma that fuels fusion facilities designed to harvest on Earth the fusion energy that powers the sun and stars.

he algorithm, devised by a scientist at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL), applies machine learning, the form of artificial intelligence (AI) that learns from experience, to develop the predictions. “Usually in physics, you make observations, create a theory based on those observations, and then use that theory to predict new observations,” said PPPL physicist Hong Qin, author of a paper detailing the concept in Scientific Reports. “What I’m doing is replacing this process with a type of black box that can produce accurate predictions without using a traditional theory or law.”

Qin (pronounced Chin) created a computer program into which he fed data from past observations of the orbits of Mercury, Venus, Earth, Mars, Jupiter, and the dwarf planet Ceres. This program, along with an additional program known as a ‘serving algorithm,’ then made accurate predictions of the orbits of other planets in the solar system without using Newton’s laws of motion and gravitation. “Essentially, I bypassed all the fundamental ingredients of physics. I go directly from data to data,” Qin said. “There is no law of physics in the middle.”

The process also appears in philosophical thought experiments like John Searle’s Chinese Room. In that scenario, a person who did not know Chinese could nevertheless ‘translate’ a Chinese sentence into English or any other language by using a set of instructions, or rules, that would substitute for understanding. The thought experiment raises questions about what, at root, it means to understand anything at all, and whether understanding implies that something else is happening in the mind besides following rules.

Qin was inspired in part by Oxford philosopher Nick Bostrom’s philosophical thought experiment that the universe is a computer simulation. If that were true, then fundamental physical laws should reveal that the universe consists of individual chunks of space-time, like pixels in a video game. “If we live in a simulation, our world has to be discrete,” Qin said. The black box technique Qin devised does not require that physicists believe the simulation conjecture literally, though it builds on this idea to create a program that makes accurate physical predictions.

This process opens up questions about the nature of science itself. Don’t scientists want to develop physics theories that explain the world, instead of simply amassing data? Aren’t theories fundamental to physics and necessary to explain and understand phenomena?

“I would argue that the ultimate goal of any scientist is prediction,” Qin said. “You might not necessarily need a law. For example, if I can perfectly predict a planetary orbit, I don’t need to know Newton’s laws of gravitation and motion. You could argue that by doing so you would understand less than if you knew Newton’s laws. In a sense, that is correct. But from a practical point of view, making accurate predictions is not doing anything less.”

Machine learning could also open up possibilities for more research. “It significantly broadens the scope of problems that you can tackle because all you need to get going is data,” [Qin’s collaborator Eric] Palmerduca said…

But then, as Edwin Hubble observed, “observations always involve theory,” theory that’s implicit in the particulars and the structure of the data being collected and fed to the AI. So, perhaps this is less a new way of knowing, than a new way of enhancing Fernández-Armesto’s third way– reason– as it became the scientific method…

The technique could also lead to the development of a traditional physical theory. “While in some sense this method precludes the need of such a theory, it can also be viewed as a path toward one,” Palmerduca said. “When you’re trying to deduce a theory, you’d like to have as much data at your disposal as possible. If you’re given some data, you can use machine learning to fill in gaps in that data or otherwise expand the data set.”

In either case: “New machine learning theory raises questions about nature of science.”

Francis Bello

###

As we experiment with epistemology, we might send carefully-observed and calculated birthday greetings to Georg Joachim de Porris (better known by his professional name, Rheticus; he was born on this date in 1514. A mathematician, astronomer, cartographer, navigational-instrument maker, medical practitioner, and teacher, he was well-known in his day for his stature in all of those fields. But he is surely best-remembered as the sole pupil of Copernicus, whose work he championed– most impactfully, facilitating the publication of his master’s De revolutionibus orbium coelestium (On the Revolutions of the Heavenly Spheres)… and informing the most famous work by yesterday’s birthday boy, Galileo.

source

<span>%d</span> bloggers like this: