Dec 05 2022

Square Kilometer Array

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Construction begins this week on what will be the largest radio telescope in the world – the Square Kilometer Array (SKA). This project began more than 30 years ago, in 1991, as an idea, with an international working group forming in 1993. It took three decades to flesh out the concept, create a detailed design, secure the land rights, and secure government funding. The first antennas will go online by 2024 with more added through 2028 (which will complete the first phase – about 10% of the total planned project). This will result in a radio telescope array with a total area of one square kilometer.

There are actually two components to the total array. One is being built in Australia, the SKA-Low, for low frequency. These will use antennas that look like two-meter tall metal Christmas trees. There will be 500 arrays of 256 antennas for a total of 131,000 antennas. This will be the low frequency array, able to detect radio waves between 50 megahertz and 350 megahertz. There will also be SKA-Mid in South Africa, which will be an array of 197 dishes sensitive between 350 megahertz and 15.4 gigahertz. The whole thing will be connected together, with the bulk of the computing power located in the UK.

Why do astronomers connect radio receivers together? This has to do with interferometry – the ability to combine two signals so that they can simulate a single receiver with a diameter equal to the distance between the two receivers.  It’s not the same as having one giant dish, however. An array increases the resolution of the received image, but the sensitivity is still a function of the total receiving area (not the distance). The Very Large Array (VLA) in New Mexico has radio dishes on rails, so that they can be moved into different configuration. By moving the dishes apart you can achieve greater resolution, but by moving them closer together you get greater precision – so there is a trade-off from moving receivers farther apart. There is no substitute for total collecting area, which is why the SKA will have so many individual receivers.

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Dec 02 2022

Evolution Is Not a Straight Line

Published by under Evolution
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Yesterday I wrote about the fact that technological development is not a straight line, with superior technology replacing older technology. That sometimes happens, but so do many other patterns of change. Often competing technologies have a suite of relative strengths and weaknesses, and its hard to predict which one will prevail. Also, competing technologies may exist side-by-side for long periods of time. Sometimes, after experimenting with new technologies, people may revert to older and simpler methods because they are in the mood for a different set of tradeoffs.

Similarly, biological evolution is not a simple straight line with “more advanced” species replacing more primitive ones. Adaption to the local environment is a relative thing, and many biological features have a complex set of tradeoffs. With technological evolution (any cultural evolution) ideas can come from anywhere and spread in any pattern (although some are more likely than others). Biological evolution is more constrained. It can only work with the material it has at hand, and information is passed down mostly vertically, from parents to child. But there is also horizontal gene transfer in evolution, there is hybridization, and even back mutations. The overall pattern is a complex branching bush, spreading out in many directions. Any long term directionality in evolution is likely just an epiphenomenon.

Paleontologists try to reverse engineer the multitudes of complex branching bushes of evolutionary relationships using an incomplete fossil record and, more recently, genetic analysis. But this can be extremely difficult because it may not always be obvious how to draw the lines to connect the dots. The simplest or most obvious pattern may not be true. A recent discovery involving bird evolution highlights this fact. It is now pretty well established that birds evolved from theropod dinosaurs. The evidence is overwhelming and convincing. Creationists, who predicted that birds would forever remain an isolated group, have egg on their face.

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Dec 01 2022

Ancient Shipwreck Reveals Complex Trade Network

People tend to understand the world through the development of narratives – we tell stories about the past, the present, ourselves, others, and the world. That is how we make sense of things. I always find it interesting, the many and often subtle ways in which our narratives distort reality. One common narrative is that the past was simpler and more primitive than it actually was, and that progress is linear, objective, and inevitable. I remember watching The Day the Universe Changed with James Burke when in one episode he declared that the Dark Ages were a time of great technological advancement. This seemed at odds with what I had been told, but I later confirmed this view that the so-called “Dark Ages” were maligned by later Renaissance writers congratulating their own progress.

The same is true of our image of technological advancement, that it’s objective and inevitable. This became more clear to me when researching my latest book, The Skeptics’ Guide to the Future. One story in particular is the sequence of the material ages – the stone age giving way to the copper age, then bronze age, and finally iron age. Metallurgy was clearly a huge technological advance, and did progress significantly over time. But this sequence was not strictly linear, older technologies persisted alongside newer technologies for different applications, and sometimes technological shifts are more of a lateral move than a clear advance.

The biggest example from the sequence above is the transition from relying mainly on bronze for tools and weapons to iron. Iron, it turns out, is not objectively better than bronze for many applications. Bronze is actually a very useful metal – it can be cast, it is easy to work with, it is strong, and it doesn’t rust. That last feature, not rusting, makes it superior to iron for many applications, even into the Renaissance (until the development of stainless steel). Bronze is actually stronger than iron and can be worked more easily, at a lower temperature. Until the development of carbon steel, there was no reason to favor iron over bronze. Why, then, did the change happen?

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Nov 28 2022

The Challenge of Green Aviation

There is some good new when it comes to decarbonizing our civilization (reducing the amount of CO2 from previously sequestered carbon that our industries release into the atmosphere) – we already have the technology to accomplish most of what we need to do. Right now the world’s electricity generation is 63.3% from fossil fuels. We have the technology, through wind, solar, geothermal, hydroelectric, and nuclear power, to completely replace this if we wanted to.  We can debate the quickest and most cost-effective path, but there are many options that will work.

About 84.3% of total energy used by the world, however, is from fossil fuel. This includes not only electricity, but transportation, heating, and industrial use (other than through electricity). Of the transportation sector, 92% is ground vehicle (cars, trucks, and shipping). Battery electric vehicle technology is now more than capable of being the primary option for most users, with ranges >300 miles for passenger cars and 500 miles for shipping. Prices still need to come down, but they will as production ramps up.

Another way to look at this is that 73.2% of our carbon footprint comes from all energy, 18.4% from agriculture, 3.2% from waste, and 5.2% from direct industrial processes (like making cement and steel). Agricultural, waste, and industrial sources of carbon are complex, and these mostly require technological advances that we will hopefully chip away at over the next few decades. But we can rapidly eliminate that 73.2% from energy if we want to, with the exception of the 8% of transportation carbon from aviation. That remains a tough nut to crack.

The challenge of aviation is that jets and planes need to be light and have limits on size, so they require an energy source that has high energy density (energy per volume) and specific energy (energy per mass), more so than ground transportation. Right now the optimal fuel for those two features is hydrocarbons. This means that the best option for greener aviation is using biofuels (sustainable aviation fuel). Biofuels can be used with existing aircraft and have similar energy density and specific energy to existing fuels. The carbon footprint is usually not zero, but is much lower than fossil fuels. The carbon footprint of biofuels depends on the feedstock used and the methods of growing used. There are also land and water-use issues with mass-producing biofuels for aviation or other purposes. The best options are those that use waste feedstock.

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Nov 23 2022

Closed Loop Pumped Hydro

I have been writing a lot recently about global warming and energy infrastructure. This is partly because there is a lot of news coming out of COP27, but also because both here and on the SGU there has been some lively and informative discussion on the issue. Also, this is a very complex issue and as people raise new points it sends me down different rabbit holes of information. I am trying to develop the most complete and objective picture I can of the situation.

The goal, of course, is to rapidly decarbonize the energy infrastructure of the world. We not only need to do this, we need to do it quickly and cost-effectively. Further, we need a plan for the next 30 years, and essentially we don’t have any second chances left. If we want to stay as far below 2.0 C temperature rise as possible, and even shoot for that rapidly fading hope of keeping below 1.5 C, then we have one shot. This means that if we have to course correct after 20 years, this may still improve the situation but will likely be too late to meet our climate goals.

I find that the most compelling arguments from experts to be those who advocate essentially doing everything. We should pick the low-hanging fruit, do all the win-wins, but also hedge our bets. If anything we want to overshoot.

One contentious issue has been whether or not it is feasible and advisable to plan on a 100% renewable energy infrastructure. The conversation gets complicated by some technical terms, so let me define them here.

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Nov 22 2022

Genes and Language

There are now approximately 8 billion people on the planet. In addition, there are over 7,100 languages spoken on Earth. One question for anthropologists and linguistic experts is – how closely do genetic relationships match language relationships. Both language and genes are generally inherited from our parents – well, genes absolutely, but language generally. It makes sense that a map of genetic relatedness would closely follow a map of linguistic relatedness. If we zoom out from a single family to a population, the question becomes a bit more complex. Populations can mix genes with other populations. Two populations that derived relatively recently from a common population will likely be genetically similar, and even if their current languages differ, they too likely share a common root and therefore lots of similarities.

What happens, then, when scientists overlay the genetic and linguistic maps of humanity? A recent study does just that. To do this they compiled a massive database, called GeLaTo, or Genes and Languages Together. GeLaTo includes data from “4,000 individuals speaking 295 languages and representing 397 genetic populations.” That is fairly robust, but there is also lots of room for continuing to add information to the database to add more precision and detail to any analysis.

What they found is that the match between genes and language is very good, about 80%. However, that still leaves 20% of identified genetic populations with a language mismatch. How does this happen? It doesn’t take much imagination to think of a scenario where a population takes on the language of another population in their region that is genetically distinct. For example:

Some peoples on the tropical eastern slopes of the Andes speak a Quechua idiom that is typically spoken by groups with a different genetic profile who live at higher altitudes. The Damara people in Namibia, who are genetically related to the Bantu, communicate using a Khoe language that is spoken by genetically distant groups in the same area. And some hunter-gatherers who live in Central Africa speak predominantly Bantu languages without a strong genetic relatedness to the neighboring Bantu populations.

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Nov 21 2022

Artificial Muscles

There are some situations in which biology is still vastly superior to any artificial technology. Think about muscles. They are actually quite amazing. They can rapdily contract with significant force and then immediately relax. They can also vary their contraction strength smoothly along a wide continuum. Further, they are soft and silent. No machine can come close to their functionality.

In engineering parlance, a muscle is an actuator – a component that causes part of the machine to move. Boston Dynamics has produced some impressive results using standard actuators, but even their robots’ movements tend to be, well, robotic – a bit jerky and stilted. Compare that to the movements of a jaguar, for example. Engineers have been working on developing muscle-like actuators for years, with some progress but far from ultimate success.

One of the properties of a biological muscle is called the force-velocity relationship – the faster the muscle fibers contract the more power they produce. A second is the force-length relationship, essentially the longer the muscle the more power it creates. As a recent study points out:

However, it still remains a challenge to realize both intrinsic muscle-like force-velocity and force-length properties in one single actuator simultaneously.

In addition to these properties, to be more muscle-like we would need an actuator that can smoothly vary its power and also have soft components. There are other important properties, such as intrinsic response to load (does the system react to a load by contracting), static force (maintaining a load without moving), and the strength of the material used (how much of a strain can it take). Researchers, therefore, have been essentially trying to duplicate the structure and function of actual muscle to achieve all these properties. In the above study, for example:

This study presents a bioinspired soft actuator, named HimiSK (highly imitating skeletal muscle), designed by spatially arranging a set of synergistically contractile units in a flexible matrix similar to skeletal musculature. We have demonstrated that the actuator presents both intrinsic force-velocity and force-length characteristics that are very close to biological muscle with inherent self-stability and robustness in response to external perturbations.

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Nov 18 2022

The Potential of Geothermal Energy

As we discuss the optimal path forward for the next 30 years to get to net-zero carbon emissions for the energy sector, one big variable is the real-world potential of geothermal energy. Right now in the US geothermal produces 0.4% of our electricity. That is almost negligible, and is not going to help get us to our goal without an order of magnitude or more increase. What is the probability that we can bring significant geothermal online within 20-30 years?

Producing electricity at large scale is mostly about turning turbines, which rotates a magnet within a coil of conducting cable which generates electrical current in the wires. Turbines are turned by two basic methods – mechanical or with steam which in turn is generated by some heat source. Hydroelectric and wind turbines rotate the turbines through mechanical power. Burning fossil fuel or nuclear power plants produce heat to create steam. Solar photovoltaics are the exception because they directly turn sunlight into electricity through the photoelectric effect. But direct solar capture can use sunlight to once again heat a target, create steam, and turn a turbine.

Geothermal energy uses steam created by the natural heat below the surface of the earth to turn a turbine to make electricity. In a recent TEDx talk, Matt Houde who is the cofounder of a geothermal energy company points out that there is enough heat in the ground to power our world for a billion years. It’s a practically unlimited energy source. Why isn’t that, then, problem solved – all the energy we can need for the foreseeable future (arguably longer than human civilization is likely to last on earth) is right beneath our feet? The problem is – that heat is hard to get to.

From my reading it seems that there are three types of geothermal energy depending on our ability to access the heat. Current geothermal, the kind making up that 0.4%, takes advantage of natural hot spring that reach near or at the surface. Boise Idaho, for example, directly heats building from natural hot springs. You can also use near surface heated water to create electrical power. This was the low-hanging fruit of geothermal, but if we want an order of magnitude increase we need to develop what is called advanced geothermal. This approach uses technology developed by the fracking industry to drill down to the heat, inject water if necessary (if water is not already present), and then use that heated water to drive turbines.

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Nov 17 2022

New Method of Speciation

Published by under Evolution
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Evolution requires that speciation events occur – events in which one species becomes two. All that is required for a speciation event to occur is that two populations of the same species stop interbreeding. There are two basic types of speciation: allopatric, where the populations are physically separated by geography, and sympatric, where they live in overlapping ranges but either can’t or don’t interbreed. For the purpose of speciation, interbreeding means producing fertile young.

Allopatric speciation is easy to understand. Most species have a large enough range that they are spread out into definable populations. They may even develop definable characteristics. Populations on the edge of a range, say a prairie species pushing into the desert, will likely develop some adaptions not possessed by the main population. At some point these adaptation may push the population into a range that does not overlap with the parent population. It also may happen that environmental change may doom the parent population to extinction, but the subpopulation’s adaptations allow them to survive as a new species. Sometimes geography simply changes, physically separating species (canyons open up, mountains rise, rivers change their course, land masses move).  Sometimes physical separation may be abrupt, such as when plants and animals find their way to islands and set up a new population, adapting to the new environment (like the Galapagos).

Sympatric speciation has been trickier to understand. Pollen will spread, animals will interbreed. It’s what they do. Research has focused on genetic events that make two populations unable to interbreed, because their offspring would be infertile. This will happen after species diverge sufficiently, but how will they diverge in the first place if they are exchanging genetic material? There must have been some genetic event, even in an individual, that instantly created genetic incompatibility. In plants this is commonly autopolyploid speciation, where the chromosome number is accidentally doubled during reproduction. The offspring cannot interbreed with the parent species because of chromosome number incompatibility. This is why some plants, like potatoes, can have very high numbers of chromosomes.

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Nov 15 2022

Cache of Ancient Bronze Statues Found

Archaeologists have uncovered a large cache of over 50 small bronze statues in the ruins of an ancient temple in Tuscany. The find dates from the second century BCE to the first century ACE. It is being reported as the greatest bronze statue find in 50 years, one of the greatest finds ever, and a significant window into that period of history.

The statues themselves range from small representations of specific body parts, to statues representing the gods and up to a meter in length. These statues were deliberately tossed into a thermal spring within the temple, where they sunk to the bottom and were covered in mud. The mud preserved the statues in relatively good condition for the last two thousand years. Many of the statues also have writing on them, in either Roman or Etruscan. Archaeologists believe that these statues were offerings to the gods intended for healings. The body parts represent the ailment that the offerer wishes to be healed. They also found over 5,000 gold, silver, and bronze coins that were tossed into the spring over those three centuries.

Essentially, this thermal spring and temple were the equivalent of a spa for the wealthy. Bathing in hot springs was a common luxury for the wealthy of the time, and this temple was also clearly not a public place. Rather, this was likely a private location for the wealthy and elite. The bronze statues would have been very expensive, only affordable just to be tossed into the waters by the very wealthy.

It’s easy to become smug from our modern perspective about the primitive behavior of making offerings to imaginary gods in hopes of being healed. But I think the opposite reaction is more appropriate. Certainly making such offerings in the genuine hope of being healed is pure superstition, and also completely useless in terms of effecting real change to one’s health. Given the primitive state of medicine at the time, however, it was also pretty harmless (and an archaeological boon, it turns out). Even the wealthy and powerful did not have access to what we could consider basic health care, and so tossing expensive bronze statues was the best they had.

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