Numerous cultures throughout history have viewed the arrival of falling celestial objects as bizarre omens or supernatural events. In fact, a quantified study of impact craters wasn’t established until the early 20th century when geologist Daniel Barringer hypothesized that some craters were formed, not by volcanic forces, but by asteroids, meteorites, comets, and other debris of the like. Even then, this explanation wasn’t fully accepted by the astronomical community until the 1960s, and several instances of these formations, both on our world and others, remain perplexing to this day.
The Carancas Impact Event:
On the 15th of September, 2007, 11:40 local time, a chronditic meteorite, composed of compact dust from the early solar system, crashed in the Puno region of Peru, several miles outside the village of Carancas. The impact itself left behind a crater 13 m (43 ft) in width and 4.5 m (15 ft) deep, filled by several feet of ground water. The following day, nearly 100-200 Peruvian residents who had visited the location of the crater began complaining of symptoms including dizziness, severe headaches, diarrhea, and vomiting, prompting the local authorities to consider declaring a state of emergency. However, in virtually every case, total recovery was reported within as little as five days. It was initially assumed that the impact’s residual heat caused the local ground water (known for its arsenic contamination) to evaporate into toxic fumes. However, further examination suggested that the meteor’s iron-rich composition allowed it to retain additional heat, vaporizing another chemical in its interior called troilite, a rare mineral containing sulfur. No similar ailments have since been reported from the crater’s area, but the cause of the illness still remains debated.
Latin for “Ogre Bowl,” Orcus Patera is a large, elliptical depression of unknown origin on Mars’ surface, around halfway between the volcanoes Olympus Mons and Elysium Mons. Measuring 380 km (240 mi) in length, 140 km (90 mi) in width, and just 500 m (1600 ft) in depth, Orcus Patera is known for its smooth and abnormally featureless base, suggesting that it is likely younger than the surrounding landscape. The basin’s well-defined shape is emphasized by two major regions of elevation on either side, at some points nearly 1,800 m (5,900 ft) higher than Mar’s average topography. Despite Orcus Patera’s relative proximity to volcanic sights (and the fact that the actual term ‘patera’ is normally assigned to irregularly shaped volcanoes), no definitive explanation of the basin’s nature has been confidently established. Theories range from numerous smaller impacts that were joined together by erosion, to violent tectonic compression of an already existing crater, or a small object that hit Mars at an oblique angle of just 5º above the horizon.
The Tunguska Event:
Leveled trees near the Tunguska event
Leveled trees near the Tunguska event
Artist’s rendering of the object’s detonation and continued velocity
Leveled trees near the Tunguska event
One of the mosts widely researched impacts in history, the Tunguska event is the largest impact ever directly observed on Earth. At 7:14 local time on 30th of June, 1908, in present-day Krasnoyarsk, Russia, a luminous blue streak (supposedly as bright as the sun) was observed by Evenki natives northwest of Lake Baikal. Less then ten minutes afterwards, a deafening collision was heard, the results of which were catastrophic.
The initial shockwave was equal to 5.0 on the Richter scale, producing seismic activity that was detected across nearly all of Eurasia. The resulting atmospheric disturbance created by the sudden increase in pressure was enough to shatter windows and knock people off their feet more than a hundred miles away, and triggered noticeable atmospheric fluctuations as far away as Great Britain. In total, an area of 2,150 square km (830 square mi, roughly half the area of Rhode Island) was devastated, leveling hills and flattening nearly 80 million trees. The estimated destructive force of the impact was equivalent to 10-15 megatons of TNT, just under a thousand times greater than the atomic bomb that was dropped on Nagasaki. For months afterwards the Smithsonian Astrophysical Observatory and other such establishments observed a decrease in atmospheric transparency caused by dust particles that were suspended by the impact.
The incident was not formally investigated until 1921, when Russian mineralogist Leonid Kulik determined that the incident was caused by a meteorite. However, no discernible impact crater has ever been identified. The most widely accepted explanation for this is that the Tunguska event was caused by either a comet or an asteroid between 60-190 m (200-620 ft) in diameter that detonated 6-10 km (4-6 mi) above the Earth when it came into contact with the atmosphere.
The Spider (officially designated Pantheon Fossae) is an ominous formation on the planet Mercury, discovered on the 14th of January, 2008 by NASA’s unmanned orbiter, MESSENGER. Resembling nothing before seen in either astronomy of geology, the Spider consists of a central crater measuring 41 km (25 mi) wide, surrounded by more than a hundred flat-floored troughs that run hundreds of miles outwards. Researchers are still in debate over whether the branching valleys were a direct consequence of the impact or if the craters was later formed over top of them.
The Patomskiy Crater:
The first picture of the Patomskiy crater, taken 1971
The Patomskiy Crater
Sometimes referenced to as the Kolpakov Cone, the Patomskiy crater, located in the Irkutsk region of southeastern Siberia, was first discovered in 1949 by Russian geologist Vadim Kolpakov, although the native people had long known of the its existence. It is composed of a limestone mound lacking most vegetation, measuring 40 m (130 ft) in height, 12 m (530 ft) in diameter, with an estimated internal volume of 230-250 thousand cubic meters (750-820 thousand cubic ft), with and additional 12 m (40 ft) high mound positioned at is center.
No definitive calculation of its age has ever been verified, with estimates ranging from the 17th century to as early as the 19th century. This vague approximation is primarily due to the crater’s inconclusive origins. Geophysicists claim that the overall shape is not characteristic of an impact crater, and that it was most likely the result of a deep gas reservoir suddenly breaking through the surface. However, dendrochronological analysis (tree-ring dating) of the older trees surrounding the crater has yielded evidence of an abrupt reduction in growth around 1842, as well as a noticeable increase in heat and/or radiation (neither of which would be present in the case of a gas rupture). Others claim that the Patomskiy crater is the compressed footprint of a meteorite impact that has been exposed by erosion, or the result of two separate objects impacting the same spot, one after the other, but at different speeds. More exotic hypotheses involve a radioactive meteorite, UFOs, or even a stray fragment of the Tunguska meteorite.
In all its remarkable and seemingly unlimited diversity, life on planet Earth has its fair share of oddities, at least from the perspective of humans. But one peculiar organism may trump all others: the opabinia. A rare species of marine arthropod that is believed to have lived nearly 540 million years ago, all that remains of the opabinia are twenty or so decent fossils discovered in the Burgess Shale layer in British Colombia. The first of these fossils were discovered by Charles Doolittle Walcott in 1912, who derived the animal’s name from the Opabin mountain pass where they had originally been unearthed. But the opabinia didn’t gain much acknowledgment until 1975, when British paleontologist Harry B. Whittington published an extensive paper concerning its physiology. Indeed, during the first presentation of Whittington’s findings, the audience at first laughed at its anomalous appearance and assumed it was a gag.
The opabinia ranged from 1.6-2.8 inches (4-7 centimeters) in length, with a primarily soft body and a series of lobed gill flaps running down the length of its sides, which not only provided it oxygen but also functioned as rudimentary legs. Its V-shaped tail was particularly unusual for an aquatic animal, almost resembling a fan in structure. From the top its head sprouted five independent eyestalks, making it one of the few known organisms to possess an odd number of fully-functional eyes. Perhaps strangest of all was its trunk-like proboscis that ended in a flexible claw, used to feed nutrients in to the backwards-facing mouth on its underside. It is widely debated whether the opabinia preyed on smaller invertebrates or was a scavenger that sought out carcasses along the seafloor.
As it possessed no definitive exoskeleton, very few specimens have survived, and the resulting pressure of the sedimentation process flattened and distorted many of the internal features of the remaining fossils.
The opabinia’s official classification remains a much disputed topic among paleontologists, as the organism doesn’t seem to resemble any other known species. The most prevailing theory suggests that the opabinia was a distant relative of modern-day tardigrades (pictured below), strange animals in their own right.
Being one of the most stereotyped icons of science-fiction, black holes have inevitably become distorted in the public’s eye, and no shortage of misconceptions and myths have circulated concerning their nature. The idea of some indomitable cosmic force devouring anything and everything can admittedly be a captivating one. Indeed, black holes have played major roles in literary works and films alike, such as Arthur C. Clarke’s debut novel The City and the Stars, Star Trek (2009), Interstellar (2014), and Disney’s creatively titled film The Black Hole (1979), among many others. But modern science didn’t actually begin to unravel the properties of black holes until the late 1950s during the rise of the golden age of general relativity. Before then, black holes were often thought of as abstract, inescapable maelstroms of nothingness, with little elaboration beyond that. It seems a vast majority of people have held to this inaccurate perspective, despite our advancements in astronomical knowledge. The early idea of black holes was actually first postulated in 1783 by British philosopher John Michell in a letter written to Henry Cavendish of the Royal Society. In it, he detailed the rough concept of a spherical body of such gravitational attraction that nothing, not even light, could escape its influence. However, without the necessary mathematical application, the idea didn’t get anywhere until the early twentieth century, when Albert Einstein developed his theory of general relativity, having earlier proven that light is indeed affected by gravity. Theories involving black holes were later expanded by influential scientists such as Karl Schwarzschild, Subrahmanyan Chandrasekhar, Robert Oppenheimer, Stephen Hawking, and others, but it wasn’t until 1976 that physicist John Wheeler coined the actual term “black hole.”
On The Formation of Black Holes:
As you probably already know, black holes are commonly formed by stars whose own mass have caused them to collapse inwards, increasing in density and gravity. Actually, any object of sufficient density would do, but stars tend to be the most readily available candidates. Stars survive billions of years because the gravitational attraction of their mass balances the outward pressure of their nuclear fusion. Therefore, a star meets its demise when one of these two forces (generally the former) becomes greater than the other. Most stars lass than eight times the mass of the Sun experience relatively uneventful deaths. After accumulating material and swelling into a red giant, the star sheds its outer layers when the rate of fuel intake becomes inadequate to support it. What is left behind is the exposed stellar core, otherwise known as a white dwarf. However, most stars larger than eight times the mass of the Sun take a very different route. Near the end of their lives, these stars can expand up to almost 2,000 times larger than the Sun, becoming red supergiants. The immense interior temperature fuses lighter elements in the core into heavier ones: first helium into lithium, later lithium into beryllium, and onwards until only iron remains, the densest material capable of being forged in stars. Once the entirety of the core has been converted into iron, the force of the nuclear fusion can no longer support the star against the gravity of its newly dense core; in less than a millisecond, the star collapses in on itself. In the process, the star’s condensed state unleashes previously inaccessible potential energy, resulting in one of the most unfathomably devastating phenomena known in the universe: a supernova.
Supernovae (the plural expression) typically last just two minutes or less, but within that brief period they can release about a billion billion billion billion (that’s 45 zeros) joules of energy, equivalent to the total power output of the Sun since it was born 10 billion years ago. Supernovae can be millions or even billions of times brighter than the Sun, outshining whole galaxies (as seen in the lower left-hand corner of the image below). The brightest supernova ever observed was SN 1006, located 240,000 lightyears away, still nearly as bright as the full moon. In any event, the core of the star survives the supernova, but its fate is dictated by how massive the original star was to begin with. If the core is 1.4-2 times the mass of our Sun, it will condense even further into a neutron star. The protons and electrons are compressed so tightly together that their opposing charges cancel each other out and render the star neutrally charged.
Alternatively, if the remnant core of the star is greater than three times the mass of the Sun, its own gravity would cause it to contract even further. This process is exponential and continues until the remnant itself reaches an infinitely small radius, thus gaining infinite density, and becoming a singularity. This may seem like a practical impossibility, for how could any object shrink to an immeasurably small point? The answer still remains elusive, as all conventional understanding of physics breaks down inside a singularity. The theory could be thought of as an indication that the singularity crosses over into a realm of physics which we do not yet understand. Having been created, the singularity’s infinite gravity draws in everything in its wake, typically starting with the debris left over from the supernova. The singularity generates an impenetrably dark field around itself called an event horizon, a boundary past which light has insufficient velocity to escape. As a result, nothing that takes place inside this threshold may be observed from an external perspective (hence the name). And so the star goes dark. It is extinguished from the universe in both a bang and a whimper. And a young black hole is created.
Black Holes Come in Various Sizes:
The above description concerning the formation of black holes is not all-inclusive. It only pertains to stellar black holes, those within five and several tens times the mass of the sun and definitively formed from collapsing stars. But black holes may not always be so limited.
For instance, supermassive black holes were first hypothesized by Donald Lynden-Bell and Martin Rees in 1971 as an explanation of why the Milky Way revolves around a central point. Three years later, Sagittarius A*, the black hole that functions as the core of our galaxy, was discovered. The origins of these objects remains largely debated. One theory rather simply states that supermassive black holes were once conventional stellar black holes that have devoured large quantities of material (perhaps even other smaller black holes), causing their gravity to greatly increase alongside their mass. However, another model holds supermassive black holes to be the product of quasi-stars. Quasi-stars are hypothetical objects that may have existed in the very early universe, when stars weren’t contaminated by any elements heavier than hydrogen and helium, which allowed them to grow nearly 7,000 times the size of the Sun (considerably larger than any stars around today). When the cores of these gargantuan stars inevitably collapsed into black holes, their own mass was capable of containing the resulting supernova. But even with the supernova prevented, there was still the matter of the newly formed black holes sitting snuggly at the star’s core. It turns out that if a black hole forms in the heart of a tremendous and still active star, the resulting compression of material rushing inwards actually increases the rate of nuclear fusion. This in turn balances the inward gravitation of the black hole with the outwards pressure of the star’s expansion. While the black hole does continue to eat away at the star’s interior, the process in slow enough for the star to continue growing for millions of years more. Eventually though, the the star can hold out no longer. It collapses completely, birthing a black hole of monstrous proportions, around which a whole galaxy may orbit.
On the opposite end of the spectrum, black holes can be unbelievably tiny. The most widely accepted hypothesis concerning the origins of microscopic black holes, called the primordial black hole theory, suggests that the early universe may have been dense enough for microscopic black holes to spontaneously form in any given region. No such conditions are to be found in the universe anymore, but scientists may be capable of creating an artificial black hole here on Earth. The LHC (Larger Hadron Collider), located in Switzerland, is not only the worlds largest particle collider but the worlds largest single machine. Though the LHC was initially constructed for the purposes of locating the Higgs boson, the conditions within an active particle collider could possibly create a dense enough area with an escape velocity exceeding the speed of light, the exact definition of a black hole. The only problem is that one would require a ring accelerator nearly 1570 lightyears in circumference to keep the particles on track. However, some alternative theories state that the aid of extra dimensions in space could allow a particle collider of the LHC’s specifications to create such an object. The idea of a black hole, however small, being manufactured several miles outside of Geneva has aroused some alarm. Understandably so. However, such black holes would only exits for an instant before vanishing. Why? That happens to be the topic of the next part…
Black Holes May Not Be Immortal:
While the analogy between a black hole and a malevolent deity may at first seem befitting, some credible theories suggest that not even a black hole’s eternity is guaranteed. In 1974, renowned physicist Stephen Hawking put forward the theoretical argument that quantum forces could cause a black hole to emit particles and “evaporate.” His theory states that vacuum energy fluctuations (another complicated topic entirely) near the event horizon causes the creation of particle-antiparticle pairs; one falls into the black hole while the other escapes, before the pair can eliminate each other as they normally would. The particle that escapes has positive energy, thus giving the illusion of the black hole emitting particles. The antiparticle on the other hand falls into the black hole. Since Einstein’s equation E=mcˆ2 states that energy and matter are directly related, the negative energy is equivalent to negative mass. Therefore, every antiparticle that is eaten by the black hole annihilates with a particle inside, reducing its mass by exactly one particle. If left to its own devices for long enough a black hole may very well disappear completely.
Black Holes are Time Machines Into the Future:
Einstein’s theory of relativity also states that the fabric of space-time behaves almost like a single medium that is bent and distorted by the mass of the objects that inhabit it. This is most often represented in a simpler, two-dimensional setting, such as the image below. The range and intensity of the distortion is directly proportional to the mass of the object itself. The larger the object, the more space-time is bent out of shape. The properties of this phenomena may sound familiar already: it’s what causes gravity. When smaller objects are gravitationally drawn towards larger ones, it is because they are literally falling into the larger distortion. In a way, gravity could be thought of as no more than a consequence of space-time being reshaped. But, because time and space are one, gravity only represents half of the equation. It turns out that time decelerates in the vicinity of massive objects. As outlandish as this idea might seem, it has already been observed and proven here on Earth. Chronometers on orbital satellites have been known to run faster than they normally would on the planet below. Similarly, astronauts who spend extended periods of time in orbit are actually aging slower than the rest of the population on Earth. The margin of difference is only a fraction of a second off and may take years before even becoming measurable. The phenomena manifests in gradients, meaning as one departs from a significant source of gravity, time becomes less and less distorted, just as gravity diminished with distance. Admittedly, a few fractions of second doesn’t seem like much. If want to see this effect on a larger scale, black holes should offer more noticeable and exotic results. If you were to fall towards a black hole, observers sitting at a distance would see you gradually diminish in speed as your near the event horizon, eventually coming to (what would seem like) a complete halt. You wouldn’t actually be sowing down, time just wouldn’t run as swiftly for you. But as you would be oblivious to this fact, from your perspective everything would appear normal in your vicinity and the rest of the universe would seem to accelerate greatly. The exact difference ratio of time distorted by a black hole remains a highly debated topic, so no one knows how long it would actually take you to reach the event horizon, though a majority of speculations calculate it would be years, or even decades.
The White Hole Theory:
As may be expected, white holes are objects that exhibit the inverted properties of black holes. The alternative Einstein-Cartan theory of gravity proposes that no singularity forms at the center of a black hole. Consequently, if no such singularity exists, all the matter absorbed by the black hole wouldn’t just accumulate for all eternity. Instead, it would be forced back through the fabric of space-time elsewhere, creating a Schwarzschild wormhole, in which matter is drawn in from one point and expelled in another. To anyone at the polar extremity of this wormhole, they would observe a spherical body that constantly emits particles and radiation, the processed remains of whatever fell into the black hole. The white hole would still possess a considerable gravitation field, but regardless of how close and object is drawn, it would never be able to surpass the event horizon from the outside. If this theory proves accurate, it would imply that black holes are nothing more than the entrances to naturally occurring wormholes…