Posts Tagged ‘fermi paradox’

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As a scientific concept, extinction is distinguished from its theological and apocalyptic variant by the work of naturalists and zoologists such as Georges Cuvier and the Comte de Buffon. Attempting to discover a scientific framework for studying life that would avoid the religious framework of the Great Chain of Being, the study of fossils became a key locus for investigating the emergence and disappearance of living beings. Cuvier, in particular, became a proponent of “catastrophism,” the theory that the Earth is periodically visited by sudden, cataclysmic events that not only radically alter the Earth’s geological composition, but the organisms living on the Earth as well. In the late 18th and early 19th century, Cuvier published a number of archaeological studies that established extinction as a scientific reality, culminating in his multi-volume work, Recherches sur les Ossemens Fossiles de Quadrupeds. As Cuvier provocatively notes, behind the revolutions of nations there lies another type of revolution, that of the planet itself:

“The ancient history of the globe, the definitive term towards which all research tends, is also in itself one of the most curious objects to have captured the enlightened mind; and, if one allows oneself to follow, in the infancy of our species, the nearly invisible traces of so many extinct nations, one will also find there, gathered in the shadows of the Earth’s infancy, the traces of revolutions anterior to the existence of all nations.”

~ In The Dust Of This Planet

Everybody talks about the Tunguska Event, nobody mentions the Carrington Event.

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“In the past two days, the sun has unleashed three monster solar flares from a sunspot group the size of Jupiter. These powerful phenomena are amazing to watch, but if they were pointed toward the Earth, they would spell big trouble. Radiation from the sun’s coronal mass ejections (CMEs) could disrupt our power grids and satellites.

Unfortunately, the sun and its atmosphere are devilishly hard to predict. But new research published today in Nature reveals new information about how CMEs form, which could help scientists improve their forecast.”

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All this may seem like doomsaying, but the historic record suggests otherwise: The Halloween Storm, in fact, pales in comparison to several earlier events. In 1989, ground currents from a less intense geomagnetic storm knocked out a high-voltage transformer at a hydroelectric power plant Quebec, plunging the Canadian province into a prolonged 9-hour blackout on an icy winter night. A far more extreme geomagnetic storm washed over the Earth in May of 1921, its magnitude illustrated in world-girdling aurorae and in fires that broke out in telegraph offices, telephone stations, and railroad routing terminals — sites that sucked up geomagnetic currents traveling through nascent power grids. An even more extreme storm in September 1859 caused geomagnetic currents so strong that for days telegraph operators could disconnect their equipment from battery power and send messages solely via the “auroral current” induced in their transmission lines. The 1859 storm is known as the “Carrington Event,” after a British astronomer who witnessed an associated solar flare and connected it with the subsequent earthbound disturbances.

“The physics of the Sun and of Earth’s magnetic field have not fundamentally changed, but we have,” Kappenman says. “We decided to build the power grids, and we’ve progressively made them more vulnerable as we’ve connected them to every aspect of our lives. Another Carrington Event is going to occur someday.” But unlike in 1859, when the telegraph network was the sole technology endangered by space weather, or in 1921, when electrification was in its infancy, today’s vulnerable systems are legion.

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Not everyone is optimistic that our modern society will successfully address the problem—including physicist Avi Schnurr, who is also the president of the Electric Infrastructure Security Council, a non-governmental organization advocating space-weather resilience. “If a Carrington Event happened right now it probably wouldn’t be a wake-up alarm—it would be a goodnight call,” he says. “This is a case where we have to do something that is not often successfully achieved by governments, and certainly not by democracies: We have to take concerted action against a predicted threatening event without having actually experienced the event itself in modern times.”

Protecting the power grid on Earth is, in principle, relatively straightforward. (Countries such as Finland and Canada have already begun to take action, with promising results.) Most high-voltage transformers are directly connected to the ground to neutralize power surges from lightning strikes and other transient phenomena. They’re vulnerable to space weather because geomagnetic currents flow upward through these ground connections.

By placing arrays of electrical resistors or capacitors as intermediaries between the ground and critical transformers, like those serving nuclear power plants and major metropolitan areas, that connection would be severed—and the space-weather threat greatly reduced if not entirely eliminated. Experts estimate this could be accomplished within a few years, at a cost of hundreds of thousands of dollars per transformer. In practice, however, it’s not so easy. So far, U.S. power companies have balked at voluntary installation of such devices, and current government regulations don’t require such protections.

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In a paper published on arXiv, an online repository, two astronomers, Tsvi Piran of the Hebrew University of Jerusalem and Raul Jimenez of the University of Barcelona, argue that some regions of the galaxy are less friendly to life than others. Moreover, the friendly areas may have been smaller in the past than they are now. If that is true, then it may be the case that complex life on Earth is just about as ancient as it is possible for complex life to be. And, since complexity necessarily precedes intelligence, that might mean human beings really are the first intelligent life forms to evolve in the Milky Way.

Dr Piran and Dr Jimenez are interested in gamma-ray bursts (GRBs), the most energetic phenomena yet discovered in the universe. No one is certain what causes them, but the leading theories are a hypernova—the sudden collapse of a massive star to form a black hole—or a collision between two neutron stars, the ultra-dense remnants of supernovas (slightly less massive collapsed stars). What is not in doubt is their prodigious power: a typical GRB generates as much energy in a few seconds as a star will in its entire multi-billion-year lifetime. That would be bad news for any life-bearing planet which was too close.

The idea that a nearby GRB (nearby, in this context, means within about 10,000 light-years) would wreck the biosphere of an Earthlike planet was proposed in 1999 by James Annis of Fermilab, in Illinois. First, the blast of radiation would instantly kill most living organisms on or near the surface—not just those facing the blast but also, via secondary showers of charged particles and re-emitted gamma rays, those on the hemisphere facing away from it. Second, the gamma rays would also stir up chemical reactions that create ozone-killing molecules sufficiently powerful to destroy more than 90% of an Earthlike planet’s ozone layer, and keep it destroyed for several years. This would let in intense ultraviolet light from the planet’s parent star, which would blitz any complex biological molecules it hit. Anything that survived the initial blast would thus be subjected to years of serious sunburn.

The Earthlike planet of most interest to human beings is, of course, Earth itself. Mankind’s home is 4.6 billion years old, and Dr Piran’s and Dr Jimenez’s model suggests there is almost a 90% chance that it has been hit by at least one GRB of this power in that period. For the first half of Earth’s existence, only the direct impact would have mattered, since there was no ozone layer to annihilate (the simple bacteria which existed at this time were either adapted to UV, or lived underground or underwater and were thus immune to its effects). But once photosynthesis started (about 2.3 billion years ago), oxygen—and therefore ozone, the triatomic form of that element—began to accumulate, and living things came out of hiding and got used to living under its protection. From then on, a nearby GRB would certainly have caused a mass extinction.

Any extinction that happened before about 540m years ago, when shelly animals appeared and fossils became commonplace, would probably be invisible in the geological record. But since then there have been five—one of which, that at the end of the Ordovician period, has no obvious explanation. Perhaps not coincidentally, Dr Piran’s and Dr Jimenez’s model suggests there is a 50% chance Earth has been struck by a GRB in the past 500m years.

SUPPLEMENTARY NOTES #FRINGECULTURE

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Follow this multi-disciplinary, scientific study as it examines the evidence of a great global catastrophe that occurred only 11,500 years ago. Crustal shifting, the tilting of Earth’s axis, mass extinctions, upthrusted mountain ranges, rising and shrinking land masses, and gigantic volcanic eruptions and earthquakes–all indicate that a fateful confrontation with a destructive cosmic visitor must have occurred. The abundant geological, biological, and climatological evidence from this dire event calls into question many geological theories and will awaken our memories to our true–and not-so-distant–past.

Everybody talks about the Tunguska Event, nobody mentions the theorised several orders of magnitude greater Younger Dryas Impact. Why is that?

The Younger Dryas impact hypothesis, also known as the Clovis comet hypothesis, is one of the competing scientific explanations for the onset of the Younger Dryas cold period. The hypothesis, which scientists continue to debate, proposes that the climate of that time was cooled by the impact or air burst of one or more comets..

The general hypothesis states that about about 12,900 BP calibrated (10,900 14C uncalibrated) years ago, air burst(s) or impact(s) from a near-Earth object(s) set areas of the North American continent on fire, disrupted climate and caused the extinction of most of the megafauna in North America and the demise of the North American Clovis culture after the last glacial period. The Younger Dryas ice age lasted for about 1,200 years before the climate warmed again. This swarm is hypothesized to have exploded above or possibly on the Laurentide Ice Sheet in the region of the Great Lakes. Though no major impact crater has been identified, the proponents suggest that it would be physically possible for such an air burst to have been similar to but orders of magnitude larger than the Tunguska event of 1908. The hypothesis proposed that animal and human life in North America not directly killed by the blast or the resulting wildfires would have suffered due to the disrupted ecologic relationships affecting the continent.

Further reading: Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling – R. B. Firestone, A. West, et al

Recent evidence continues to oppose the YDB impact hypothesis. New research, which analyzed sediments claimed, by the hypothesis proponents, to be deposits resulting from a bolide impact were, in fact, dated from much later or much earlier time periods than the proposed date of the cosmic impact. The researchers examined 29 sites that are commonly referenced to support the impact theory to determine if they can be geologically dated to around 13,000 years ago. Crucially, only 3 of the sites actually date from that time. According to the researchers, the Younger Dryas impact event evidence “fails the critical chronological test of an isochronous event at the YD onset, which, coupled with the many published concerns about the extraterrestrial origin of the purported impact markers, renders the YDIH unsupported. There is no reason or compelling evidence to accept the claim that a cosmic impact occurred ∼12,800 y ago and caused the Younger Dryas.

Further readingOBSERVATION OF 23 SUPERNOVAE THAT EXPLODED <300 pc FROM EARTH DURING THE PAST 300 kyr -R. B. Firestone

Firestone (2014) asserted evidence for numerous (23) nearby (d<300 pc) supernovae within the Middle and Late Pleistocene. If true, this would have strong implications for the irradiation of the Earth; at this rate, mass extinction level events due to supernovae would be more frequent than 100 Myr. However, there are numerous errors in the application of past research. The paper overestimates likely nitrate and 14C production from moderately nearby supernovae by about four orders of magnitude. Moreover, the results are based on wrongly selected (obsolete) nitrate and 14C datasets. The use of correct and up-to-date datasets does not confirm the claimed results. The claims in the paper are invalidated.