Born in New York City in 1933, Steven Weinberg became interested in science thanks to the childhood gift of a chemistry set. In 1950 he became the first member of his family to attend college receiving a bachelor’s degree in physics from Cornell University and then his Doctorate from Princeton.
Steven Weinberg as I’m certain he’d like to be remembered, working on Physics! (Credit: UT News – The University of Texas at Austin)
Doctor Weinberg then began his career as a researcher at Columbia University before accepting temporary teaching assignments at the University of California in Berkeley, Harvard University and the Massachusetts Institute of Technology. He finally settled down in 1982 at the University of Texas in Austin where he would remain for the rest of his life teaching both physics and astronomy.
Robert Lee Moore hall at the University of Texas at Austin houses the departments of Physics, Math and Astronomy. Steven Weinberg had his office here. (Credit: Big Dave 4444)
The key moment in Doctor Weinberg’s career came in 1967 when he published a short, three page paper in the journal ‘Physical Review Letters’ entitled ‘A Model of Leptons’. In that paper Weinberg theorized that the weak nuclear interaction, best known for beta decay where a neutron transforms into a proton plus an electron and an anti-neutrino, could best be understood if it were unified with the familiar Electromagnetic interaction. In particular Weinberg predicted the existence of both charged and neutral current paths thru which his unified force would propagate.
Top of ‘A Model of Leptons’ by Steven Weinberg. (Credit: Twitter)
Weinberg’s ideas would soon be extended by his colleagues Abdus Salam and Sheldon Lee Glashow to become the Electro-Weak force that was carried by four boson particles, the W particle, which comes in both positive and negative charged varieties along with the neutral Z particle and the photon. At that time only the familiar photon had been detected in the labouratory but experiments in the 1970s would discover the other three making Weinberg one of the only scientists who could say that he predicted the existence of three particles before they were discovered in the lab.
Official announcement of the 1979 Nobel Prize for Physics. (Credit: Nobel Foundation)
By combining two of the four known forces of nature, which are gravity, electromagnetism, and the strong and weak nuclear forces Weinberg had partially succeeded in something that Albert Einstein unsuccessfully worked on for the last 25 years of his life. Einstein had sought to unify gravity and electromagnetism into a single geometric theory but unlike his earlier success with general relativity a unified field theory eluded him.
The Standard Model of Elementary Particles. Weinberg was responsible for predicted the W and Z particles. (Credit: SLAC)
The success of the Weinberg-Salam-Glashow theory led to its three contributors being awarded the 1979 Nobel Prize in physics and set the stage for a whole plethora of ‘Grand Unified Theories’ or GUTs throughout the 1980s and 90s. The final theory that came about from these efforts was ‘Supersymmetry’ that is based on the simple idea that there is really only one kind of particle and that all of the different particles we see in our labouratories are actually just different quantum states of that one kind of particle. The major prediction of supersymmetry was that every known particle would have to be coupled to a supersymmetric ‘partner’ that balanced all of the known particle’s measured quantities.
The failure of Supersymmetry. The theory predicts the existence of a SUSY partner (r) for every particle in the Standard Model (l). To date none have been found!! (Credit: Quanta Magazine)
Throughout the last thirty years Weinberg was a contributor and proponent of supersymmetry. (By the way supersymmetry is not quite the same as string theory, the idea that elementary particles are little strings that vibrate. String theory fits very well with supersymmetry however and today it’s hard to find a physicist who is working in supersymmetry that doesn’t use string theory.) Unlike electro-weak theory however none of the partner particles predicted by supersymmetry have been discovered so that today most theorists are searching new paths to try to explain the standard model of particles that we know.
String theory asserts that every king of particle is just a vibrating string. The way a string vibrates determines which particle in the Standard Model they behave like! (Credit: SpringerLink)
The First Three minutes by Steven Weinberg. Weinberg was one of those scientists who were able to describe the mysteries of the Universe in terms more average people could understand. (Credit: Amazon.com)
In addition to his own work in particle physics Steven Weinberg was also the author of several books popularizing science including ‘Dreams of a final Theory’ about particle physics and ‘The First Three Minutes, a Modern View of the Origin of the Universe’, which describes in clear language the big bang. Doctor Weinberg was also a longtime advocate for nuclear disarmament. Steven Weinberg belonged to the post-war generation of physicists that included such brilliant minds as Richard Feynman, Murray Gell-Mann and Robert Higgs, to name a few. For these scientists Relativity and Quantum Mechanics were well established models to build upon and together they helped to develop the standard model that is today the basis of our understanding of the Universe.
Ever since physicists began experimenting with the nuclei of atoms they realized that producing energy by the fusion of light nuclei had several advantages over the splitting, fission of heavy nuclei. For one thing fusion simply produces more energy than fission but more importantly fusion does not produce the large amounts of radioactive waste that are the biggest problem with our current nuclear power plants.
The series of fusion reactions that power our Sun. Scientists have been trying to develop a simplified version of these reactions as a power source for more than 60 years now. (Credit: SpringerLink)
The big problem with using nuclear fusion to generate power is that it’s so hard to initiate. Whereas a nucleus of Uranium 235 is so unstable that almost any disturbance, like a stray neutron striking it, will cause it to split into smaller nuclei a hydrogen nuclei, really just a proton, will electrostatically repel any other proton making it very difficult to force them to fuse together. This is because the strong nuclear force keeping nuclei together is incredibly short ranged; you practically have to get the protons to touch in order for them to stick. The electromagnetic (EM) force on the other hand obeys an inverse square law like gravity does and never really goes to zero.
An nucleus of U235 is so unstable that all it needs is to be ‘bumped’ by a neutron and it will split, releasing energy in the process. That’s why fission reactors are actually easy to build but because the leftover atoms are radioactive fission reactors are very hard to make safe!!!! (Credit: Atlearner)
In the center of the Sun fusion is only possible because of the extreme pressures and temperatures there. So in order to generate fusion in the labouratory scientists and engineers have for over 60 years tried to replicate the conditions at the center of the Sun.
The fusion reaction that scientists are trying to control in order to produce power. This reaction releases most, around 80%, of its energy in the form of neutrons that are both dangerous and difficult to convert into electricity. (Credit: Nuclear Information Center – Duke Energy)
The usual design for these attempts has been a doughnut shaped vacuum chamber inside a very powerful magnetic field known as a Tokamak. Inside the Tokamak an ionized gas known as a plasma is heated to millions of degrees Celsius and contained by the magnetic field. Once the fuel reaches a high enough temperature some of the nuclei begin to fuse releasing energy that can then be converted into electric power. The ITER fusion reactor, which is currently under construction in France, is expected to operate at a plasma temperature of 150 million degrees Celsius!
The Tokamak at ITER (Center glowing) will be the largest plasma chamber ever constructed with the most powerful magnetic field. In order to function properly the Tokamak will be surrounded by a large number of different support facilities. (Credit: New Scientist)
The fuel used in most fusion experiments are heavy isotopes of hydrogen, also known as deuterium and tritium, D-T, which consist of a single proton attached to either a single neutron or two neutrons respectively. The reason that heavy hydrogen is the fuel of choice is that with only a single proton in each nuclei the repelling force is minimized, the greater the number of protons the greater the repelling EM force and the higher temperature needed to force fusion to occur.
D-T has one big drawback however, about 80% of the energy released is by the emission of free neutrons. These neutrons are not only dangerous to living tissue, and therefore require a large amount of shielding around a fusion reactor, but it is also difficult to covert the kinetic energy of neutral particles into useful electric power. High energy charged particles however can be directly converted in electric power by several techniques, moving electric charges is the definition of electric current after all.
In a particle accelerator electricity is used to accelerate charged elementary particles. The process can also be reversed, using energetic charged particles to generate electricity directly. (Credit: Wikipedia)
For this reason there has been a lot of interest recently in several other fusion reactions that are considered to be ‘aneutronic’ with only a very small amount of the energy generated being released by neutrons, the majority coming from charged particles. Three aneutronic reactions in particular are being studied:
Helium Three, that’s two protons with a neutron, with Deuterium
He3+D→He4+p +18.3 MeV of Energy
Fusion using Helium 3, two protons and a neutron, would be the easiest to produce and control. However H3 is extremely rare here on Earth. (Credit: Weekly Science Quiz)
Lithium 7, three protons and four neutrons, with a proton
Li7+p→2He4 + 17.2 MeV
Boron 11, five protons and six neutrons, with a proton
B11+p→3He4 + 8.7 MeV
Several aneutronic fusion reactions. The question is which can be developed more easily while providing the greatest amount of usable energy. (Credit: depts.washington.edu)
The first reaction, Helium 3 and Deuterium requires the lowest temperature of any of the aneutronic reactions and releases the most energy of any of the three reactions. The problem is that Helium 3 is virtually non-existent here on Earth. Traces of Helium 3 have been found in samples of rocks brought back from the Moon and which space scientists theorize was produced by billions of years of the solar wind striking the Lunar surface.
Science fiction writer have picked up on this availability ofthis potential energy source on the Moon and several novels have been written using Helium 3 mining as a reason for establishing a Lunar colony. However obtaining even a few useful kilograms of Helium would require processing millions of kilos of Lunar regolith, a endeavour well beyond our current space technology. Maybe one day a large Lunar colony will supply Earth with fuel for its fusion reactors, but that’s many decades in the future.
There are measurable traces of Helium 3 in the Lunar dust but getting usable quantities of it would be an enormous enterprise. (Credit: Extreme Tech)
That leaves Lithium and Boron as possible fuels for an aneutronic fusion reactor and while neither element is especially abundant there is still more than enough to keep thousands of fusion reactors running for centuries. As shown in the reactions above Lithium fusion releases the greater amount of energy but is generally not considered aneutronic because as much as 10% of the energy is released as neutrons by the secondary reaction:
Li7+p→Be7+n
Boron on the other hand releases less than 1% of its energy by neutrons but also releases less than half the energy of the other two. Both lithium and Boron would require a plasma temperature of more than 600 million degrees Celsius in order to produce a sustained fusion reaction.
The higher the cross section at a lower center of mass energy the lower the temperature required for the reaction. Deuterium – Tritium is certainly the best while Helium 3 and Boron require much higher temperatures. (Credit: MuonRay)
So there you have it. Aneutronic fusion may provide some definite advantages over heavy hydrogen fusion but because of the much higher temperatures required it’s difficult to see how they can be implemented any time in the near future. Without some unexpected technical breakthrough it seems inevitable that the first nuclear fusion reactors will be based on heavy hydrogen as a fuel.
A proposed Aneutronic Reactor from LPPFusion Corporation. They’re still looking for funding so it may be years before they start construction. (Credit: LPPFusion)The most powerful magnet ever manfactured. One of six that will fit inside the center if the ITER Tokamak it is now on its way from its manufacturer in the US to southern France. (Credit: Daily Mail)
Which is why it’s a sign of progress that the most powerful magnet ever built has been shipped from its manufacturer General Atomics in the United States to southern France. The magnet is the first of six sections of what will become the central core of the ITER reactor. At a 18m in height and 4m in width with a mass of 100 metric tonnes the section cannot be transported by road and is being shipped by a specially prepared ship to the ITER site. Once all six sections are assembled the magnet will produce a field of 13 Tesla or about 280,000 times the strength of the Earth’s magnetic field. It is hoped that the first section will be installed by November.
“Shipstar” is the second in a series of three novels by noted science fiction authors Gregory Benford and Larry Niven. I reviewed the first novel in the series “The Bowl of Heaven” back on the 2nd of January 2021. As we began “The Bowl of Heaven” the Earth starship Sunseeker was on a mission to establish the first human colony in another star system on a planet that is given the name Glory.
Cover Art for the Novel ‘Shipstar’ by Gregory Benford and Larry Niven. (Credit: Amazon)
In mid flight however Sunseeker encounters an unbelievable sight, a star that has been almost completely enclosed inside a shell. Such an object is commonly known as a Dyson sphere after physicist Freeman Dyson who proposed that such a structure would allow a high-technology civilization to capture and use the entire energy output of the enclosed star.
The bowl of heaven in the SF series by Gregory Benford and Larry Niven. (Credit: Centauri Dreams)
Now the star encountered by Sunseeker is not a complete Dyson sphere, there is a large hole in the sphere making the object more like a bowl, “The Bowl of Heaven” in the title. And the star’s solar wind has been magnetically channeled through that hole to provide a rocket exhaust making the star and it’s bowl into a ship, a “Shipstar”.
Investigating this marvel the Sunseeker sails inside the bowl and sends down a landing party to the inside surface of the bowl. On the surface the humans discover a large number of different intelligences, each of which appear to inhabit their own area on the inside of the bowl. The aliens who run the bowl, and who refer to themselves as ‘The Folk’ turn out to be rather domineering and capture half the landing party while the other half escapes into the bowl. After a series of adventures this is where “The Bowl of Heaven” ends.
View from the inside surface of the bowl. Two parties of humans are trapped upon the bowl, trying to survive and escape in “Shipstar’. (credit: Tor / Forge Blog)
“Shipstar” picks up where “The Bowl of Heaven” left off with half the landing party being interrogated by the folk while the rest are trying not to get caught. The first three-quarters of “Shipstar” consist of these adventures as the Earthlings learn more about the creatures that inhabit the bowl. Before long it becomes obvious that while the folk may appear to be in charge they clearly aren’t the original builders of the bowl. Several times in the novel one human character or another thinks to themselves “we’re missing something here” as the authors try to build up tension for the big reveal to come.
Did ya ever get that feeling? (Credit: Meme Generator)
So the first three hundred pages of ‘Shipstar” are pretty much action-adventure, the escaped humans actually get involved in a rebellion by one of the other intelligent species on the bowl against the folk. The adventures and the aliens encountered are all interesting enough but really they’re just filler.
Maybe every story needs a protagonist and antagonist but Science Fiction needs more than just conflict, it needs big ideas about the nature of the Universe and our place in it! (Credit: Teachers pay teachers)
And that’s my problem with all of these SF series lately. The author or authors may start out with a good enough idea but because they have to spread it over three or more books the story becomes mostly filler, more like a western than real SF. Conflict is important in any story, you learn that your first day in any writing course, every story needs its protagonist(s) and antagonist(s). Science Fiction however is about big ideas not just a series of shootouts and fistfights.
Larry Niven (t) with Gregory Benford (b), or is it the other way around. They actually do resemble each other a bit don’t they. Anyhow they’re with the cover of ‘Glorious’ the next chapter in the ‘Bowl of Heaven’ series. (Credit: Tor / Forge Blog)
Now as I said, with two top-notch SF writers like Benford and Niven the filler is worth reading and in the last hundred pages of “Shipstar” we do finally get some information, some resolution as well as a setup for the next book in the series. The story of the voyages of the Sunseeker and the Bowl of Heaven continues in “Glorious” and I’ll be certain to tell you all about it before too long.
I’ve just watched Jeff Bezos and his New Shepard spacecraft complete their eleven minute trip to the edge of space and I have to admit I’m underwhelmed. The fact that a private citizen can now accomplish what NASA succeeded in doing back in 1961 with Mercury-Redstone does not seem like much progress to me even though the news media insist on calling the flight ‘historic’.
Liftoff of the New Shepard spacecraft on it’s first manned trip to the edge of space. Aside from the number of crew and the fact that the rocket is reusable the whole trip was a replay of Alan Shepard’s 1961 Mercury-Redstone flight. (Credit: The New York Times)
The date of Blue Origin’s first manned flight on the 20th of July was deliberate to honour the 52nd anniversary of Neil Armstrong’s becoming the first man to set foot on the Moon. And Bezos also chose his crew with an eye to making headlines by including female aviation pioneer Wally Funk, who trained as an astronaut back in the early 1960s only to have NASA completely ignore her. At 82 years of age Wally also became the oldest person to travel into space while fellow passenger Oliver Daemen became the youngest at 18. All of which is good advertising for a company looking to establish its market share in a new industry.
The crew of New Shepard. From right to left Mark Bezos, Jeff Bezos, Wally Funk and Oliver Daemen. (Credit: CNN)
It is true that unlike Alan Shepard’s flight the world’s richest man was able to take three other people with him and while Shepard could barely move around in his Mercury capsule the New Shepard capsule has enough room for everyone to enjoy zero g for a few minutes. Nevertheless New Shepard is really nothing more than a thrill ride, the world’s biggest, and by far most expensive roller coaster ride.
Aside from a couple of minutes at Zero G your average roller coaster is about as thrilling, and costs a lot less than a flight on New Shepard. (Credit: Wikipedia)
Bezos’ company Blue Origin expects two more flight’s of New Shepard this year and as many as half a dozen next year. If enough people are willing to pay the yet to be officially announced ticket price then Blue Origin could build more spacecraft to accommodate more flights and maybe before to long several hundred people a year could be getting their astronauts wings.
The US Department of Transportation has designed the above medal for those who will go into space aboard commercial space services. NASA, the Air Force and Navy all have their own version. (Credit: Parabolic Arc)
The same is pretty much true of Richard Branson’s Virgin Galactic flight to the edge of space nine days earlier on July 11th. Branson’s SpaceShip 2 is actually based upon the US Air Force’s X-15 program, again a program from the early 1960s. The X-15 proper was a rocket plane that was attached beneath an Air Force bomber and lifted about 20 kilometers into the atmosphere. There the X-15 was dropped from the mother plane so that it could light its engine and fly to the edge of space before returning as a glider, just like the later space shuttle.
Virgin Galactic’s SpaceShip 2 (C), being carried to launch altitude by its especially designed mothership. (Credit: Deseret News)
Virgin Galactic’s SpaceShip 2 and its mothership follow basically the same flight path, the mothership carries SpaceShip 2 aloft and then drops it so that it can ignite its engines and fly off to the edge of space. The only real difference is that unlike the X-15, which carried only its pilot, SpaceShip 2 can carry up to six people, five paying passengers plus the pilot and once again contains enough room for those passengers to enjoy zero g for a few minutes.
As with the New Shepard flight the crew of SpaceShip 2 got to enjoy a few minutes of Zero G. Richard Branson is the one still in his harness. (Credit: Reuters)
So if both flights just mimicked missions from the early 60s why did the news media make such a hullabaloo about them? Worst of all was the argument over whether or not Branson had actually gone into space. You see the US government insists on using imperial measurements and therefore defines space as an altitude of 50 miles. (I wonder if that’s the first time I’ve mentioned miles in these posts.) The rest of the world uses SI units and defines space as 100 kilometers, equivalent to 62 miles. Bezos and New Shepard crossed both boundaries but Branson and SpaceShip 2 only reached the lower altitude so they will have an asterix next to their status as astronauts. As if it really matters.
The launch of Alan Shepard aboard Freedom 7. This Mercury-Redstone flight on 5 May 1961 was similar to the flight New Shepard took. (Credit: NASA)
I suppose by now you thinking that I’m a real party pooper. Why can’t I just be excited that more people are going to get the chance to travel into space? After all, that will help build up more enthusiasm for space travel while developing new technologies that could be useful on more scientific and exploratory missions. And remember that both New Glenn and SpaceShip 2 are completely reusable, won’t that help to develop new, reusable technology for space travel in general.
The flight of SpaceShip 2 was patterned after the flight of the X-15, also from the early 1960s. (Credit: Wired)
Maybe, but it is worth mentioning that another billionaire, Elon Musk and his Space X corporation have already succeeded in launching ten astronauts, real astronauts that is, into orbit along with numerous unmanned payloads with his reusable Falcon 9 rocket. And Musk at least has had the good sense, or perhaps good manners would be a better description, not to send himself into space in one of his crew dragon capsules. Seriously the fact that Space X is winning contracts to place useful payloads into orbit or beyond does kind of make the short, sub-orbital flights of Virgin Galactic and Blue Origin seem like nothing more than joyrides.
Space X has already launched 10 astronauts into orbit, where they can some actual work. Somehow to me that makes Branson’s and Bezos’ joyrides seem less historic. (Credit: Space News)
Looking into the future it is true that Blue Origin is developing a larger version of their rocket that will be both reusable and capable of placing payloads into orbit. This would make the company a direct competitor of Space X, which could help to further lower costs and therefore increase space travel in general.
Blue Origin plans on the first flight of its New Glenn rocket, which will be bigger than the falcon 9, sometime next year, 2022. (Credit: YouTube)
To the best of my knowledge however Virgin Galactic has no plans to develop any orbital version of their space plane. The company appears to be content to carve out a business taking rich people just high enough above the Earth’s surface so they can tell their friends that they’re now astronauts.
In recent years the commercialization of space has begun to pay off some real dividends. Astronauts are being taken to the International Space Station in larger numbers and at far less cost than either Russia’s Soyuz or the old Shuttle could do while the cost of unmanned space missions have also gone down. So I suppose the carnival surrounding the first launches of New Shepard and SpaceShip2 are a small price to pay for the progress that is being made.
At birth we humans are perhaps the most helpless of creatures. Unable to move let alone find food or take care of ourselves in any way we are utterly dependent on other humans for our survival. For that reason the very first thing our brains are designed to do is recognize another person, especially another human face.
Most living creatures have to be able to take care of themselves from the moment they are born. We however are probably the most helpless of creatures, utterly dependent on other humans to provide for us. (Credit: The Washington Post)
This instinct is true of virtually all mammals and birds, even some reptiles. Since the first thing we see after birth is usually our mother we imprint on her. And since humans have always lived in groups we quickly imprint on the other members of the group, our father, siblings, and other relatives.
Most vertebrate babies imprint on their mother and follow her wherever she goes, learning how to live from her. So its very important that the babies are able to recognize her immediately. (Credit: DOGO News)
It also very important that we be able to recognize the mood other people are in. Crying for food when your mother is angry, or perhaps frightened because a predator is near is more likely to get you a slap than a meal. The shape of a smile, or a frown, and what they mean also appears to be built into our brains even before we are born. And as we grow older we become attuned to the more subtle facial expressions the different members of our group have, this ability aids in our communications with those around us.
We humans use our faces to let the world know how we’re feeling. It’s important that babies learn to interpret these expressions as fast as possible. (Credit: MDPI)
So important is our ability to detect and analyze another human face that we are unconsciously looking for human faces all the time, and all to often finding them in objects that are completely non-human. We’re all familiar with this psychological phenomenon; we’ve all at one time or another seen a human face in almost anything that vaguely resembles two eyes, a nose and mouth. Artists sometimes even toy with our mind by generating face like shapes out of things that are completely non-human.
Literally anything can appear to us to have a face. Human faces are just something we are designed to see. (Credit: KickVick)
Psychologically this phenomenon is called pareidolia and studies have shown that our minds will even attribute emotions to non-living objects if we see a face in them. Perhaps even stranger is the fact that the feeling of seeing a face, and emotions in that face will persist even after we realize our mistake and recognize that the thing we are anthropomorphizing isn’t even alive.
It’s not just humans who see faces everywhere. Here’s a dog seeing a dog’s face in a knothole. (Credit: Bored Panda)
Now a new study by neuroscientists at the University of Sydney in Australia and the National Institute of Mental Health in Bethesda in Maryland has examined both how a pareidolia face is detected and how the ‘expression’ on that face is analyzed. In the experiment a group of 17 student volunteers were shown a sequence of images of both actual human faces and illusionary faces on non-living objects. Forty images of each type were used with the human faces expressing emotions ranging from happy to neutral to angry.
Alternating between real human faces and pareidolia the psychologists at University of Sydney and the National Institute of Mental Health studied the reactions of their volunteer subjects. (Credit: Alais, Xu et al, Proceedings of the Royal Society)
The students were shown the images alternating between human and non-living with each image being shown eight times for a total of 320 trials. Although each image was shown eight times the order of the images was randomized so that a non-living image would follow different human faces. The students were asked to rate the emotion of the faces on both the human and illusionary faces as they saw them.
And the face doesn’t have to be head on from us to ‘see’ it. Here are a couple of facial profiles in a vase! (Credit: Etsy)
What the researchers found was that the emotional rating of the non-human faces was profoundly influenced by the emotion on the face of the human image immediately preceding it. This result indicates that our brain detects and then analyzes false faces in exactly the same manner as it does an actual human face rather than discarding the detection as a mistake. In addition, by controlling the time that the volunteers saw each image the researchers were able to estimate that our brains require only a few hundred milli-seconds to analyze even a pareidolia face.
It actually takes us only a small fraction of a second to analyze the expression on another person’s face. (Credit: ProProfs)
According to Professor David Alais of the University of Sydney’s school of Psychology and lead author of the study, “From an evolutionary perspective, it seems that the benefit of never missing a face outweighs the errors where inanimate objects are seen as faces.”
We even recognize expression in non-human objects. Does this tree trunk look thoughtful to you? (Credit: Imgur)
Which goes to show that our brains are already programmed with a variety of instincts and behaviors before we are even born, instincts and behaviors that may have served our pre-human ancestors well but some of which may actually be harmful in our modern world. We need to better understand the way our brains work if we are ever going to control the prejudices and impulses acquired by our ancestors millions of years ago.
So if we realize that we are instinctively born to see human faces in everything why do we insist that faces on other planets have to be the work of aliens? (Credit: NASA)
In the late 18th century, as astronomers first got some accurate distances to the various planets in the Solar System they noticed a wide gap in the space between Mars and Jupiter. Then during the first half of the 19th century a large number of smaller bodies, now called asteroids were discovered and the idea of an asteroid ‘belt’ between Mars and Jupiter where the chunks of a failed planet orbited the Sun was developed.
The asteroid belt sits between the orbits of Mars and Jupiter. There are also two smaller groups of asteroids held by massive Jupiter in its orbit known as Trojan asteroids because astronomers started giving them names from Homer’s poems. (Credit: ZME Science)
Basically the idea was that the gravity of nearby Jupiter, the most massive of all the planets caused so many perturbations in the orbits of the asteroids that they never succeeded in merging into a single body. Today we know of the existence of hundreds of bodies in the asteroid belt.
Are the asteroids a ‘failed planet’ that never succeeded in coming together because of Jupiter’s strong gravitational field? (Credit: Jet Propulsion Labouratory NASA)
The sixteenth of those asteroids to be discovered was named 16 Psyche and yes the 16 refers to it being the sixteenth asteroid discovered. Psyche has recently garnered a considerable amount of attention because the latest estimate of the asteroid’s density, released in 2019, put it at a rather high value of 3.99+0.26 g.cm3. Because of its high density planetary physicists have suggested that 16 Psyche may in fact be the remains of the core of that failed planet that Jupiter prevented from coming together.
Computer enhancements of the best images of 16 Psyche taken by the Hubble space telescope. (Credit: Extreme Tech)
Now that density is far too high for the asteroid to be composed primarily of silicates like the Earth’s crust is. Psyche must be mainly, an estimated 95%, composed of metals like iron, nickel and cobalt, with perhaps even some gold, silver and copper mixed in. With all of those valuable minerals in a ball about 200km across, giving the asteroid a mass of 2.4×1019 kg, the potential value of 16 Psyche could be as high as $10,000 Quadrillion USD using current commodities prices. Before you go grab your pick ax and shovel and try to stake a claim however remember 16 Psyche never comes closer to Earth than 225 million kilometers so getting there, and getting you and your ore back to Earth, might make the whole enterprise a loosing proposition.
There’s been a lot of hype about 16 Psyche because it is possible that it contains ENORMOUS amounts of valuable metals. Right now nobody knows for certain so it really is all just hype. (Credit: The Sun)
By the way, all this talk about valuable metals on 16 Psyche reminds me of a short story by the British astronomer Fred Hoyle from back in the 60’s called ‘Element 79’. Now back when the story was written the UK was still suffering from the debt it had accrued fighting the Nazis in world war two when it gets struck by a fairly large meteorite. The impact occurs in the Scottish Highlands, which helps to minimize the loss of life. And the damage done by the impact is soon forgotten because the meteor is mainly composed of element 79, that’s gold to any of you who don’t have access to a periodic table of the elements. The mass of the meteor was about 300 billion kilograms, more than all the gold in all the world’s bank vaults and quickly made the UK the world’s richest nation.
If you can find it ‘Element 79’ by Fred Hoyle is a very interesting collection of short stories by the late British Astronomer. (Credit:
Interesting story if you can find it but getting back to 16 Psyche a recent paper by undergraduate student David Cantillo at the University of Arizona concludes that the asteroid is actually only about 85% metal, the rest carbonaceous chondrite type material. Cantillo also concludes that structurally the asteroid is not a solid object but little more than a pile of rubble held together by gravity. Still an asteroid that is 85% valuable metals would be very interesting, from a business point of view.
Currently under construction at the Jet Propulsion Labouratory (JPL), the Psyche space probe will study the asteroid in detail. (Credit: JPL)
Which view of 16 Psyche is correct we may know in just a few years because NASA is currently building a robotic space probe to visit and survey the asteroid. The probe is being funded as a part of NASA’s Discovery Program and is scheduled to be launched aboard a Space X Falcon Heavy Rocket in July of 2022, just a year from now. After getting a gravity boost from Mars the probe will reach 16 Psyche in 2026 and will orbit and survey the asteroid for at least 20 months.
The planned mission of the Psyche probe. Launch will take place in 2022 with arrival in 2026. (Credit: Earth Observer Portal)
Let’s imagine just for a minute that the probe reaches 16 Psyche and discovers that the asteroid is absolutely teeming with valuable metals, even deposits of gold are observed right on the surface. And if the asteroid is just a pile of rubble as Mister Cantillo thinks that would actually make it easier to mine. Just grab a shovel and start hefting gold into your spaceship’s cargo bay. And since the gravity of an asteroid like 16 Psyche is so low you won’t have to worry much about landing and taking off on the asteroid, just get to the asteroid belt!
Which will be easier, to mine the valuable materials from an asteroid and ship them to Earth… (Credit: Explainingthefuture.com)…or to literally drag the entire asteroid to Earth where its riches can be mined a leisure? (Credit: Sputnik News)
Think of it, commercial space ventures are just now starting to really get going, in 6-10 years they may be ready to try something beyond Low Earth Orbit (LOE), way beyond. Now of course since 16 Psyche is so far away the first miners to the asteroid will all be robots but still it just might happen that 10 years from now asteroid mining becomes a real possibility.
The small Canadian town of Lytton sits about 100 kilometers to the northeast of the city of Vancouver in British Columbia. Situated at a latitude of 50º North of the equator Lytton is hardly the place that you would expect to be competing for the honour of being one of the world’s hottest places. In fact the daily high temperature in Lytton during the hottest times of the year rarely reached above 30ºC. Or at least it did before global warming.
The little town of Lytton, red marker, sits to the NE of Vancouver in an area more commonly asso9ciated with winter sports than heat waves! (Credit: Google Maps)
(Before I go any further I just want to state again that in my opinion the green house gasses we are dumping into the atmosphere are causing Earth’s average temperature to rise, that’s global warming. But that rise in temperature can cause many different localized changes to the environment, that’s climate change. Nevertheless, I don’t care about whether you call it global warming or climate change I just want something done about it!)
Who are we trying to kid. We are putting our planet in the oven and consequences be damned! (Credit: Wikipedia)
Over the past week however Lytton has suffered under a once rare weather phenomenon called a heat dome. Simply put a heat dome is a very strong high pressure system that gets cut off from the high altitude jet stream and therefore can remain in the same location for several days or more. Now remember that in the northern hemisphere the wind blows clockwise around a high pressure system so where I live in Philadelphia the hottest days occur when there is a Bermuda high off the Atlantic coast. The clockwise flow around the Bermuda high brings warm, moist air from the Gulf of Mexico over the southern states, where it warms even further, right into the Mid-Atlantic region. Bermuda highs are generated by the warming of the waters in the western Atlantic during the summer and thanks to global warming they have been getting stronger over the last decade.
Heat domes are actually a fairly common phenomenon but like hurricanes they have been growing in numbers and strength. (Credit: The Sun)
On the west coast the high pressure systems that generate heat domes are caused by a difference in temperature, technically known as a gradient in the Pacific Ocean with the temperature rising as you go from west to east. In other words the ocean waters near Japan are relatively cool but get progressively warmer as you go east towards the North American west coast. Recalling that the air above warm water rises means that the northern Pacific can become a kind of wind tunnel pointing towards North America. These prevailing winds bring warm air onto land and sometimes during the winter those winds can become trapped against a jet stream pushing down from the Artic forming a massive high pressure system, which as the summer begins forms a heat dome.
The heat dome was generated by a blob of warm water in the waters of the northeastern Pacific. (Credit: The weather Channel)
These heat domes have appeared several times in the past few years over the US pacific northwest states leading to record high temperatures in cities like Portland Oregon and Seattle Washington. This year’s heat dome has been the largest and strongest ever seen reaching all the way from Portland, which set it’s all time record high of 46º on June28th, to the Canadian Yukon and Northwest Territories.
The heat dome diverted the jet stream around it which then actually held the dome in the same place for days baking the land beneath the dome! (Credit: CBS News)
Little Lytton sat right in the middle of the high pressure system which meant that for several days there was virtually no wind or clouds in the town. Nothing but Sunlight lasting for nearly twenty hours a day. Remember Lytton is at 50º north latitude so the days there in summer are very long. After days of baking in the Sun on June 27th Lytton broke Canada’s all time high temperature record of 45ºC with a temperature of 46.7ºC. That record was only the start however for on June 28th the high temperature in Lytton reached 47.8ºC before finally on June 29th reaching an astounding 49.4ºC, hotter than it’s even been recorded in the city of Las Vegas, Nevada. That temperature is in fact the hottest ever recorded at any latitude above 45º, north or south on the entire planet!
Temperature records aren’t just being broken they’re being shattered across the Pacific northwest. (Credit: Yahoo News)
Of course it wasn’t just Lytton that sweltered in oppressive heat, almost the entire western part of Canada and the United States have been subjected to an unprecedented heat wave in regions where it rarely gets hot, regions where air conditioning is virtually unknown. While the consequences to public health will take some time to fully determine an initial heat related death toll of 380 has been announced for Canada and at least several hundred for the US states of Washington and Oregon.
It isn’t just North America that has seen deadly heat domes. In June of 2019 a heat dome over France killed hundreds in a region not used to such prolonged high temperatures. (Credit: CNN)
So is this the new normal, it certainly does seem as if we’ve reached a tipping point where massive changes to large areas of the globe are happening right before our eyes. And the evidence has become so overwhelming that it seems as if even the worst climate change deniers have become silent. Still there’s so much we have to do if we’re to prevent even worse climate disasters, and so little time left.
Maybe Climate Change isn’t a ‘New Normal’ we want to embrace. If we don’t act soon however we may have no choice! (Credit: GraceMed Health Clinic)
Post Script: As I was writing this post the BBC broadcast a story about a wildfire that was ravaging the Canadian province of British Columbia. Caused by the excessive heat and drought conditions generated inside the heat dome the wildfire had virtually wiped out the small town of Lytton!
Only days after suffering through the highest temperatures ever in Canada the town of Lytton was burned to the ground in a massive wildfire. (Credit: Castanet)
In the earlier sections of the olde testament there are a number of groups of people mentioned who did not survive into later, better historically recorded times and who are therefore something of a historical mystery. The Moabites, Jebusites, Edomites and Ammonites were small tribes who unlike the great empires of Egypt, Assyria and Babylon left little evidence behind of their existence for later historians to study.
The Olde Testament mentions a number of the Bronze Age neighbors of the two Hebrew Kingdoms. All of whom got swallowed up by the great empires of the Iron Age. (Credit: Pinterest)
For many centuries it was thought that the Hittites were like that, a small nation of people who got swallowed up by the great empires, as the Hebrews almost did, and who disappeared from history. The early 19th century historian Francis William Newman even proclaimed that “…no Hittite king could have compared in power to the king of Judah”. Boy did he get it wrong, in fact the rediscovery of the Hittite kingdom as one of the great powers of the Bronze Age Mediterranean is among the greatest achievements of the science of archaeology.
For centuries much of what was known of the Hittites was that Uriah, the husband of Bathsheba, was a Hittite mercenary in the service of King David whom David had killed in battle so he could have Bathsheba. (Credit: Wayfarer)
The first evidence indicating that the Hittites were more important than the bible seemed to indicate was unearthed in Egypt where archaeologists came across numerous inscriptions mentioning the Hittites as an important people. In fact they discovered far more mentions of the Hittites than they did of the Hebrews. The true status of the Hittites really became clear however with the first excavations of the ruins of their capital Hattusa in north central Anatolia, that’s modern Turkey.
The Hittite Empire, in red, is centered upon their capital of Hattusa during the late Bronze Age. Wilusa in the upper left is the Bronze Age name for Troy. (Credit: World History Encyclopedia)
Although the ruins were first discovered in 1884, large-scale excavations of Hattusa only began in 1906 by the archaeologist Hugo Winckler. In addition to determining the full scale of Hattusa, which ranked in size with other great Bronze Age cities like Luxor, Nineveh or Babylon, Winckler also found the royal archives of the Hittite kings, 10,000 clay tablets inscribed in cuneiform but in an unknown language.
The famed lion gate at Hattusa. (Credit: Kathmandu and Beyond)A recreation of what Hattusa may have looked like at its peak around the year 1250 BCE. (Credit: Amusing Planet)
In the century since then much has been learned about the Hittite empire, which extended over the central and eastern portions of modern Turkey along with down the coast of modern Syria as far south as Lebanon. It is even thought by some that the city of Troy in what is now western Turkey may have been loosely associated with the Hittite empire.
In the time of the Pharaoh Rameses II, 1274 BCE, the Egyptians and the Hitties, under their king Hattusili III fought what may have been the greatest battle of the Bronze Age at Kadesh. The battle was pretty much a draw and five years later the two empires concluded a treaty that lasted more than a hundred years until the collapse of the Hittite empire.
In a Bas-relief at Luxor the Egyptian Pharaoh Ramses II declared that he won the battle of Kedesh against the Hittites pretty much single handed. In reality the battle was a draw with the two empires making a treaty and never fighting again. (Credit: Discovering Ancient Egypt)
When the language of the Hittites was deciphered from the cuneiform tables it was found to be Indo-European in nature, more closely related to Greek or Latin than Aramaic or Hebrew. Historians are of the opinion that the people who became the Hittites entered Anatolia from either the Balkans or Ukraine around 2000 BCE and either conquered of intermingled with a non-Indo-European people known as the Hattians from who the name Hattusa seems to have come.
Although they used cuneiform symbols to write the Hitties spoke an Indo-European language. Some of their tables even tell of the last days of Hattusa as the ‘Sea Peoples’ advanced on the city. (Credit: Biblical Archaeological Society)
The Hittite empire came to an end around 1200 BCE as the eastern Mediterranean world was rocked by a series of invasions by ‘Sea Peoples’ who spread destruction from Greece through Mesopotamia down to Egypt. While Assyria and Egypt both endured the barbarian assaults it was the Hittite empire that suffered the most, the capital Hattusa being burned to the ground around 1180 BCE. For a hundred or so years after that there were several smaller, less powerful nations who called themselves Hittites. Those later Hittite kingdoms did not last long however as they were all swallowed up by either the growing Assyrian empire or by the Phrygian people who settled in western and central Anatolia, and who may have been one of the ‘sea peoples’.
The Egyptians fought two great battles against the ‘Sea Peoples’. They saved Egypt but the Sea Peoples settled along the eastern Mediterranean coast to become the Philistines. (Credit: Simple Wikipedia)
Even after 100 years of archaeological research there is still much that we don’t know, or don’t understand about the Hittite people. One place that has epitomized that mystery is the sanctuary of Yazilikaya, a religious shrine with numerous rock carvings just a short distance from the walls of Hattusa. While the site of Yazilikaya, and its many bas-reliefs have been studied for a century now their meaning had eluded archaeologists.
Chamber A of the Yazilikaya shrine as it is today. (Credit: The Vintage News)
Now a new paper by a diverse group of scientists claims to have solved the riddle of Yazilikaya. The team includes Serkan Demirel of the department of archaeology at Karadeniz Technical University in Trabzon, Turkey, Eberhard Zangger, President of Luwian Studies in Zurich, Switzerland, Rita Gautschy of the department of ancient civilizations at the University of Basel in Switzerland along with E. C. Krupp, the Director of the Griffith Observatory in Los Angeles, California. By the inclusion of an astronomer in a paper about an ancient temple you can probably guess that the researchers maintain that Yazilikaya, in common with many ancient religious sites, was part temple and part astronomical observatory.
Bas-Relief on the north wall of Yazilikaya depicts the chief gods of the Hittite pantheon. (Credit: Todayunews)
In fact the rock art displayed at Yazilikaya represents both the Hittite view of the structure of the cosmos while at the same time functioning as a calendar. Like many cultures the Hittites believed the Universe to be divided into three parts, the heavens, the Earth and the underworld. Well the shrine at Yazilikaya is divided into two chambers, referred to as A and B. On the north wall of chamber A is a rock carving that portrays the northern constellations that never set below the horizon, like the Big and Little dipper along with Cassiopeia. These constellations are accompanied by carvings of the major gods of the Hittite pantheon, the storm god Teššub, his wife Ḫebat and their son Šarruma and together they represent heaven. On the two side walls of chamber A are carvings of fertility and other more Earthly types of god marching in procession toward the greater gods at to the north. They represent the Earth.
Hittite gods of the underworld carrying scythes to gather up the dead from chamber B. (Credit: Artnews.Com)
The entrance to chamber B is guarded by lion headed daemons and also contains a three-meter tall statue of Nergal, the god of the underworld. Along the wall of chamber B is a carving of twelve gods of the underworld carrying sickles, a common representation for the gathering of the dead.
The three bas-reliefs may be used as a calendar. (Credit: Zangger, Krupp, Demirel and Gautschy)
According to the study the sets of carvings, except the northern one, could be used as a calendar keeping track of both the phases of the Moon as well as the days of the year. Such archaeoastronomical alignments and religious observatories in the ancient world are coming to be accepted and studied more and more by archaeologists since the idea was first suggested for Stonehenge back in the 1960s. Many religious ideas and concepts really began as attempts by ancient man to understand the nature and movements of the sky above our heads.
The Hittites were once a powerful, wealthy people whose empire played a leading role in the beginnings of civilization during the Bronze Age. Understanding their culture and religion is necessary if we are to understand how we got to where we are.
When I was growing up I was very interested in space. Not just the space race to get to the Moon either. I knew all about the planets and their moons, the stars, galaxies etc. Back then outer space meant empty space, a vacuum, once you were out of Earth’s atmosphere there was really nothing of any interest until you got to the Moon or some other planet.
This is the way we though of the Solar System back in the 60s. Just a few planets and moons with a lot of empty space in between. (Credit: Wikipedia)
Even back then things were starting to change however. The Physicist Eugene Parker first proposed the existence of the solar wind in the mid-1950s, a prediction that was confirmed by the first interplanetary space probes in the early 1960s. Now in some ways the solar wind may seem pretty much like a vacuum, it only averages around five protons per cubic centimeter but those few particles are moving at a nominal 500 kilometers per sec generating both a large electric current and a strong magnetic field.
Astrophysicist Eugene Parker back when he predicted the existence of the Solar Wind! (Credit: University of Chicago)
As everyone knows those currents and magnetic fields can interact with the Earth’s own magnetic field to generate both the aurora and occasionally, when a particularly strong solar storm strikes, radio and TV interference and even electrical blackouts. And since the solar wind has been blowing now for four billion years it can have a large effect over time. In fact planetary astronomers now think it was the solar wind that slowly, over millions of years ripped away the atmosphere of Mars.
In our modern tech dependent world space weather is now a big deal, one that requires constant monitoring. (Credit: SpaceWeather.com)
As the solar wind spreads outward from the Sun it disperses slowly, losing strength as it reaches the outer solar system. At a distance about twice as far from the Sun as Neptune’s orbit the solar wind collides with the Interstellar Medium (ISM), the tenuous gas and ionized matter between the stars.
At the edge of our Solar System the solar wind collides with the interstellar medium forming the Termination Shock and the Heliopause. (Credit: Sci-News.com)
In many way the solar wind and the ISM are very similar. They are both near vacuums by Earthly standards and they are both composed mainly of hydrogen atoms or hydrogen ionized into protons and electrons. The big difference is in the forces pushing on those particles. The solar wind is exploded out from the Sun and carries the Sun’s magnetic field out with it while the ISM moves in response to the magnetic field of the galaxy.
The Solar Wind is not constant by any means, solar flares like this one often occur to increase the outward flow of particles while the Sun can also be almost quite at times. (Credit: CNET)
When these two electromagnetic clouds collide with each other they generate a kind of electromagnetic wall that’s millions of kilometers thick known as the Termination Shock. Here the particles of the solar wind lose most of their velocity, they just collided with a wall after all. The particles now drift slowly through what is called the heliosheath, a region of space where the solar wind and the ISM mix. Finally, beyond the heliopause is the ISM proper.
Even the space between the stars is not truly empty. There is dust and gas, some of which is ionized and gets pushed around by the magnetic field of the Galaxy. (Credit: Science at your Doorstep)
Now the bubble around our solar system formed by the termination shock and the heliosheath is not perfectly spherical. You see our Sun orbits around the center of the galaxy and as it moves both it, and the bubble produced by the solar wind push their way through the ISM. Because of this the bubble is compressed in front of the Sun’s direction of motion and elongated in the rear.
Pushing against the Interstellar wind the Heliosheath gets compressed up front but elongated to the rear. (Credit: Researchgate)
Now you may have noticed that, aside from once saying “At a distance about twice as far from the Sun as Neptune’s orbit” I haven’t been too precise about the distances from the Sun where the termination shock and heliosheath begin and end. Well, that’s because until recently we didn’t have very accurate information on those distances.
The two Voyager space probes have both passed beyond the Termination Shock and left our Solar System. Both are still working, sending back data telling us about conditions in the Interstellar Medium. (Credit: Britannica)
The first accurate measurement came from the Voyager 1 space probe, which is still continuing to send back data on conditions in the space around it 44 years after it’s launch back in 1977. In August of 2012 Voyager 1’s magnetometer saw a rapid shift in the direction of the magnetic field around it. At the same time the number of low energy particles associated with the solar wind dropped while the number of high energy particles considered to be part of the ISM began to increase. Voyager 1 had passed the termination shock and became the first man made object to enter interstellar space.
Voyager 2 followed its sister in November of 2018 giving scientists two data points about the exact size of the bubble formed by the Sun’s solar wind. But with an object that large two data points still leaves a lot unknowns. The scientists wanted more; they wanted a space probe that could measure the distance to the heliopause in many different directions from back here in Earth orbit. The wanted the Interstellar Boundary Explorer or IBEX satellite.
The Interstellar Boundary Explorer or IBEX satellite. IBEX measures the echo of the solar wind colliding with the ISM to measure the distance to the Termination Shock and Heliopause. (Credit: Pinterest)
The launch of the IBEX probe was on October 19th of 2008 by a method that is more than a bit unusual for those of us who have been watching rocket launches since we were young. The spacecraft was first placed atop its Pegasus XL rocket, which was then suspended beneath NASA’s Stargazer L-1011 aircraft. The stargazer then flew to the island of Kwajalein in the Pacific near the equator. On the 19th the Stargazer took off from Kwajalein and the Pegasus rocket was launched from the aircraft in the same fashion as the old X-15 was launched from a B-52. The IBEX probe was placed into an extremely elliptical orbit of 86,000 kilometers perigee by 260,000 kilometers apogee. In this orbit the satellite is Sun oriented, in other words always able to keep the Sun in view.
NASA’s Stargazer L-1011 aircraft ready to launch a rocket, underneath the aircraft, into orbit. (Credit: Aerotech News and Review)
IBEX makes its measurements by collecting Energetic Neutral Particles (ENPs) that are generated by the collisions between the solar wind and the ISM. On a average day IBEX detects about 600 particles but the greater the intensity of the solar wind the greater the number of ENPs.
Analysis of the data collected by the IBEX space probe. (Credit: Interstellar Boundary Explorer)
In this way IBEX can measure the size and shape of the Sun’s bubble in the same way that a dolphin uses sonar to ‘see’ what’s around it in the ocean. You see the intensity of the solar wind emitted by the Sun varies with time; IBEX then sees that same variation later in the ENPs it detects. The delay being two to six years depending on the energy of the particles and the direction IBEX is looking.
Now scientists working with IBEX at the Los Alamos National Labouratory have used that data to generate a three dimensional map of the heliosheath. At the same time the data also allowed them to calculate the speed with which the Sun’s bubble is moving through the local ISM to be 23.2 kilometers per second. The space probe has succeeded in making detailed measurements at immense distances about objects so faint that no human sense could even tell they existed.
Empty space is not really empty, there’s a lot more going on there than our human senses can perceive. (Credit: TYKMA Electrox)
All of which just shows that what we used to think of as ’empty space’ is a lot more dynamic, and a lot more interesting than we ever imagined it was back in the 1950s and 60s.
In 1859 Charles Darwin changed the world with the publication of his most famous work “On the Origin of Species by Natural Selection” commonly referred to simply as The Origin of Species. In that book Darwin provided an enormous amount of evidence for the existence of evolution as a phenomenon, that is he presented a wide variety of examples of how populations of living creatures do change with time, even on occasion splitting into different species. (Darwin by the way never liked the term evolution preferring the simpler, and more accurate “Descent with Modification”.)
A first edition of Darwin’s “On the Origin of Species” can be your for a mere $400,000 USD!!! (Credit: Raptis Rare Books)
In Origin of Species Darwin also proposed natural selection as a mechanism that drove evolution. According to natural selection on occasion an individual is born with a new trait caused by a mutation. How these mutations occur Darwin had no idea, biology at that time had no knowledge of genes or DNA, but he had plenty of evidence that they did in fact occur. If the new trait was advantageous to the individual in their environment then that individual would live longer than the other members of its species and more importantly, have more offspring who would inherit the advantageous trait. Again Darwin had no knowledge of how traits were inherited he just knew that they were. Before long the population with the advantageous trait would have out bred those without it and over time, advantageous trait by advantageous trait the species would adapt better to living in its environment. It would evolve.
How to evolve from a dog-like land animal to a whale! All by natural selection. (Credit: Live science)Darwin had no knowledge of DNA or how inherited traits were passed on from parent to offspring, he just knew they were. (Credit: Medical News Today)
But even as he argued the case for natural selection Darwin realized that there were some traits, like the long ornate feathers on a peacock or the large antlers on deer, which did not provide any obvious advantage to individuals of the species that possessed them. Darwin noticed that these traits that natural selection could not explain always seemed to be related to a difference between the male and female of the species, peahens do not have long ornate feathers nor do female deer have antlers for example. Such traits are technically called sexual dimorphisms, which Darwin realized arise because males, who produce a large number of sperm cells, benefit by having sex with as many females as possible while females, who produce a smaller number of egg cells, benefit by reproducing with the best possible males.
The gorgeous feathers of the male peacock are the classic example of ‘Sexual Selection’ since the ornate feathers do not aid the bird in any way except attracting a female. (Credit: How Stuff Works)
In Origin of Species Darwin suggested that these traits might have evolved so that an individual might gain an advantage, not in living longer but in having sex more often and called this driver of evolution Sexual Selection. In his later book “The Descent of Man, and Selection in Relation to Sex” Darwin expanded on the workings of sexual selection to describe the fighting of male elephant seals, the displays of male birds of paradise and even the calls of male songbirds.
The sometimes deadly fight between male elephant are also all about females. In order to win access to females the males have grown to more than twice the mass of their mates. Another example of sexual selection. (Credit: Scientific American)
As an example of how sexual selection works I’ll use a species of fish that I used to keep in my aquarium as a kid, the swordtail. A native species of Central America only the male swordtail has the elongation at the bottom of the tail that gives the species its name. It is a sexual dimorphism. Anyone who has kept these fish as pets knows that female swordtails prefer to mate with those males who have the longest tail and so those males have more offspring and over time the species gets longer tailed males.
A popular fish for aquariums only the swordtail male has the extension that the species is named for. Like the male peacock’s feathers the sword tail is for display not for fighting. (Credit: YouTube)
But it works on the females also. Those females who have the stronger preference for long tailed males will not only mate with those males first, but more often producing more female offspring who prefer longer tails. Sexual selection drives both sexes toward greater enhancement of the sexual trait. And in the years since Darwin’s time many examples of sexual selection have been studied largely confirming his views.
Male Red Deer fighting for the chance to mate. Another classic example of sexual selection. (Credit: Discover Wildlife)
Darwin also theorized that since it was the males who competed for the females sexual selection would become more important in species where males outnumbered females, making the competition that much more important. In other words with few females around a male would have to work harder in order to be able to mate. Recent studies however have indicated that in this one instance Darwin may have gotten things exactly backwards.
Evolutionary biologist Tamas Szekely of the University of Bath in the UK working in the field. (Credit: University of Bath)
A new paper with lead author Tamas Szekely, Professor of Biodiversity at the Milner Center for Evolution at the University of Bath presents evidence from 462 species of mammals, reptiles and birds. The study measured the strength of sexual selection on a species by the ratio of male weight to female weight. As an example consider elephant seals where the males can weight more than twice what a female weights and where the males fight tremendous battles between themselves in order to maintain a harem of females. In the species studied what the researchers found that competition amongst males was actually strongest in those species where females outnumbered males.
A lion pride usually consists of 6-12 related females with only one or two unrelated males. A recent study has found evidence that the force of sexual selection actually is strongest in species where the females outnumber the males. (Credit: Quora)
The researchers also examined some of the ways that one sex can outnumber the other in a species, since most species of vertebrate start with a 1:1 ratio at birth. Sometimes predation can be the cause of the imbalance as in the way African lions kill about six times as many male buffalo as females because males tend to graze alone while females are more likely to stay in large herds where they’re more protected. And of course the violent competition between males for females, such as in elephant seals and lions, will also lead to an shortage of males increasing the strength of sexual selection still further. Sexual selection is a powerful force in nature generating many of the odd and unusual features we see in the animals around us. Even if Darwin did get one facet of it wrong his discovery of and description of sexual selection is another one of the great achievements of that great scientist.
