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Posts Tagged ‘astronomy

“Everything we know and love about the universe and all the laws of physics as they apply, apply to four percent of the universe”*…

 

dark matter

 

In 1969, the American astronomer Vera Rubin puzzled over her observations of the sprawling Andromeda Galaxy, the Milky Way’s biggest neighbour. As she mapped out the rotating spiral arms of stars through spectra carefully measured at the Kitt Peak National Observatory and the Lowell Observatory, both in Arizona, she noticed something strange: the stars in the galaxy’s outskirts seemed to be orbiting far too fast. So fast that she’d expect them to escape Andromeda and fling out into the heavens beyond. Yet the whirling stars stayed in place.

Rubin’s research, which she expanded to dozens of other spiral galaxies, led to a dramatic dilemma: either there was much more matter out there, dark and hidden from sight but holding the galaxies together with its gravitational pull, or gravity somehow works very differently on the vast scale of a galaxy than scientists previously thought.

Her influential discovery never earned Rubin a Nobel Prize, but scientists began looking for signs of dark matter everywhere, around stars and gas clouds and among the largest structures in the galaxies in the Universe. By the 1970s, the astrophysicist Simon White at the University of Cambridge argued that he could explain the conglomerations of galaxies with a model in which most of the Universe’s matter is dark, far outnumbering all the atoms in all the stars in the sky. In the following decade, White and others built on that research by simulating the dynamics of hypothetical dark matter particles on the not-so-userfriendly computers of the day.

But despite those advances, over the past half century, no one has ever directly detected a single particle of dark matter. Over and over again, dark matter has resisted being pinned down, like a fleeting shadow in the woods. Every time physicists have searched for dark matter particles with powerful and sensitive experiments in abandoned mines and in Antarctica, and whenever they’ve tried to produce them in particle accelerators, they’ve come back empty-handed. For a while, physicists hoped to find a theoretical type of matter called weakly interacting massive particles (WIMPs), but searches for them have repeatedly turned up nothing…

Dark matter is the most ubiquitous thing physicists have never found. Is it time to consider alternative explanations? “Does dark matter exist?

[image above: source]

* Neil deGrasse Tyson

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As we interrogate the invisible, we might recall that it was on this date in 1944 that one of the worst fire disasters in U.S. history occurred; the blaze broke out during an afternoon performance of the Ringling Bros. and Barnum & Bailey Circus that was attended by an estimated 7,000 people.  It killed 167 people; more than 700 were injured.

240px-Htfdcircusfire

Because of the paraffin wax waterproofing of the tent, the flames spread rapidly

hartfordcircusfire-1024x762

Emmett Kelly holding a water bucket on what became known as “the day the clowns cried

 

Written by LW

July 6, 2020 at 1:01 am

“I’m sure the universe is full of intelligent life. It’s just been too intelligent to come here.”*…

 

aliens-1024x576

 

The Fermi paradox, named for physicist Enrico Fermi, is the apparent contradiction between the lack of evidence for extraterrestrial civilizations and various high estimates for their probability (e.g., some of the optimistic estimates for the Drake equation).  Fermi wondered, “where are they?”

By way of context, Tim Urban in his wonderful Wait But Why?:

As many stars as there are in our galaxy (100 – 400 billion), there are roughly an equal number of galaxies in the observable universe—so for every star in the colossal Milky Way, there’s a whole galaxy out there. All together, that comes out to the typically quoted range of between 1022 and 1024 total stars, which means that for every grain of sand on every beach on Earth, there are 10,000 stars out there.

The science world isn’t in total agreement about what percentage of those stars are “sun-like” (similar in size, temperature, and luminosity)—opinions typically range from 5% to 20%. Going with the most conservative side of that (5%), and the lower end for the number of total stars (1022), gives us 500 quintillion, or 500 billion billion sun-like stars.

There’s also a debate over what percentage of those sun-like stars might be orbited by an Earth-like planet (one with similar temperature conditions that could have liquid water and potentially support life similar to that on Earth). Some say it’s as high as 50%, but let’s go with the more conservative 22% that came out of a recent PNAS study. That suggests that there’s a potentially-habitable Earth-like planet orbiting at least 1% of the total stars in the universe—a total of 100 billion billion Earth-like planets.

So there are 100 Earth-like planets for every grain of sand in the world. Think about that next time you’re on the beach.

Moving forward, we have no choice but to get completely speculative. Let’s imagine that after billions of years in existence, 1% of Earth-like planets develop life (if that’s true, every grain of sand would represent one planet with life on it). And imagine that on 1% of those planets, the life advances to an intelligent level like it did here on Earth. That would mean there were 10 quadrillion, or 10 million billion intelligent civilizations in the observable universe.

Moving back to just our galaxy, and doing the same math on the lowest estimate for stars in the Milky Way (100 billion), we’d estimate that there are 1 billion Earth-like planets and 100,000 intelligent civilizations in our galaxy.1

SETI (Search for Extraterrestrial Intelligence) is an organization dedicated to listening for signals from other intelligent life. If we’re right that there are 100,000 or more intelligent civilizations in our galaxy, and even a fraction of them are sending out radio waves or laser beams or other modes of attempting to contact others, shouldn’t SETI’s satellite dish array pick up all kinds of signals?

But it hasn’t. Not one. Ever…

Perhaps. as we’ve mused here at (R)D before, life is there, but we’re not seeing it because it isn’t a form of life that we recognize: c.f., “Two possibilities exist: Either we are alone in the Universe or we are not. Both are equally terrifying” and “That is a very Earthling question to ask, Mr. Pilgrim.”

But there are some who’ve refused to give up on the search for more traditionally-defined life; indeed, a new study quantifies the “fraction” (to which Urban alludes, above) of civilizations that could (should?) be communicating around our galaxy:

One of the biggest and longest-standing questions in the history of human thought is whether there are other intelligent life forms within our Universe. Obtaining good estimates of the number of possible extraterrestrial civilizations has however been very challenging.

A new study led by the University of Nottingham and published [earlier this month] in The Astrophysical Journal has taken a new approach to this problem. Using the assumption that intelligent life forms on other planets in a similar way as it does on Earth, researchers have obtained an estimate for the number of intelligent communicating civilizations within our own galaxy -the Milky Way. They calculate that there could be over 30 active communicating intelligent civilizations in our home Galaxy…

Details at (the slightly misleadingly-titled): “Research sheds new light on intelligent life existing across the galaxy.”

* Arthur C. Clarke

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As we stay tuned, we might send far-seeing birthday greeting to Fred Hoyle; he was born on this date in 1915.  A prominent astronomer, he formulated the theory of stellar nucleosynthesis.  But he is rather better remembered for his controversial stances on other scientific matters—in particular his rejection of the “Big Bang” theory (a term he coined, derisively, in one of his immensely-popular series The Nature of the Universe on BBC radio) and his promotion of panspermia as the source of life on Earth.

220px-Fred_Hoyle source

 

Written by LW

June 24, 2020 at 1:01 am

“The grid is awesomely complex. It is the largest machine in the world.”*…

 

solar flare

Solar Flare (upper left), May 28, 2020

 

The Sun emitted its largest solar flare since 2017 on Friday, indicating that our star may be awakening from a quiet period that has lasted several years. Though the flare erupted on the opposite side of the Sun from Earth, NASA’s Solar Dynamics Observatory was able to detect its glow above the solar surface, which is visible in the upper left corner of the above image…

Solar flares, sudden bursts of light blasted out by the Sun, are sometimes accompanied by arcing ejections of hot plasma from the star. These flashes normally show up in the same area as sunspots, which are dark patches of the solar surface that are slightly cooler than other parts of the Sun.

Our star experiences solar cycles that last about 11 years and are timed by the number of sunspots visible on the surface: peak activity correlates to the largest numbers of sunspots in a cycle, while a relatively spotless Sun is considered to be in hibernation. The last cycle started in 2008, and produced a major solar storm in 2012.

These storms also cause extremely bright and vivid auroras, popularly called the Northern and Southern Lights, as the glut of charged particles from a more energetic Sun illuminates the skies. However, past incidents show that extremely powerful flares and ejections—which blast out powerful surges of X-ray and UV radiation—can also scramble satellite systems and even cause energy failures on Earth, such as a blackout in March 1989 that left millions of people in Québec without power…  (source and more info)

Indeed, after the 1989 event, earth had a near miss when the effects of a much more powerful storm barely passed us by…

Back in 2012, the Sun erupted with a powerful solar storm that just missed the Earth but was big enough to “knock modern civilization back to the 18th century,” NASA said.

The extreme space weather that tore through Earth’s orbit on July 23, 2012, was the most powerful in 150 years, [see here for info on that earlier storm] according to a statement posted on the US space agency website Wednesday.

However, few Earthlings had any idea what was going on.

“If the eruption had occurred only one week earlier, Earth would have been in the line of fire,” said Daniel Baker, professor of atmospheric and space physics at the University of Colorado…. (source and more info)

The damage, should another huge solar storm hit, could be massive– but wouldn’t be evenly distributed…

solar effect

This map shows 100-year storm-induced voltages on the national electric power grid

A new study about solar-induced power outages in the U.S. electric grid finds that a few key regions—a portion of the Midwest and Eastern Seaboard—appear to be more vulnerable than others…

Solar flares and other solar-mass ejections that travel through space can slam into Earth’s atmosphere and generate powerful electric and magnetic fields. These magnetic storms can occasionally be intense enough to interfere with the operation of high-voltage electricity lines.

Depending on the geology of a given region, the currents a geomagnetic storm induces in the power lines can destabilize the power grid’s operation and cause damage to (or even destroy) transformers….

Utilities in those [most vulnerable] regions need to know that power disturbances and outages—and possibly blown transformers—are more likely in the case of a big solar storm hitting Earth.

In a worst-case scenario… portions of the electric grid without enough backup transformers and other equipment could find themselves unable to operate until they can swap in backup systems. Of course, if there are not enough transformers and other devices, many in the hardest-hit regions could be without power for days or weeks until equipment could be delivered or built from scratch…

The worst-case scenario, the one that keeps grid experts up at night, happened last in 1859. It originated in a solar flare that blasted off the solar surface on 1 September 1859 and was observed by the English amateur astronomers Richard Carrington and Richard Hodgson.

Fortunately, when the “Carrington Event” hit Earth, the world had precious little electric infrastructure to disturb. It was mostly telegraph wires along railway lines that felt any high-voltage surges.

“There’s some expectation that if we were to have a repeat of the 1859 storm, it could have some substantial effects on the electric power grid and other technology that modern society depends upon,” [USGS research geophysicist Jeffrey] Love said. And because so many of today’s electrical systems are built around computer chips that are not robust to high-voltage surges, the fear is that a modern-day Carrington event could also blow out some portion of our computerized world…  (source and more info)

What can we do about it?  We can urge utilities (and their regulators) to expand and extend the emergency transformer stockpile (Grid Assurance) and to shore up the grid’s resilience to electromagnetic pulses.

As though we need one more thing about which to be concerned…

* Gretchen Bakke, The Grid: The Fraying Wires Between Americans and Our Energy Future

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As we have a sunny day, we might spare a thought for Joseph Ritter von Fraunhofer; he died on this date in 1826.  A  physicist and optical lens manufacturer, he made optical glass and achromatic telescope objective lenses, invented the spectroscope, and developed diffraction grating.  But he is perhaps best remembered for his discovery of the dark absorption lines in the spectrum of the sun (created by selective absorption of those wavelengths by the atoms of different elements)– now, appropriately, known as Fraunhofer lines.

220px-Joseph_v_Fraunhofer source

 

“That is a very Earthling question to ask, Mr. Pilgrim”*…

 

universe

 

What does it mean to be alive? Science, shockingly, still doesn’t have a consensus. For example, is it fair to say that the novel coronavirus now sweeping the world is alive? The short answer is there isn’t one agreed-upon answer — for something so basic, you’d think life would be easier to define.

The first recorded definition of life came from Aristotle in ancient Greece, around 350 BC. He posited that to be alive, something must grow, maintain itself, and reproduce. In contrast, the most well-known modern definition is probably NASA’s, which says living things must be “a self-sustaining chemical system capable of Darwinian evolution.” Take, for example, great apes: given appropriate resources like food and water, the “machinery” of a great ape — its organs and nervous system — regulates itself, keeping the great ape functioning in most conditions. They are also capable of evolution — just look at us. But this isn’t the only accepted definition of life. There are actually over 100 published definitions!

A lot of the debate comes down to the fact that the various fields of science approach the topic quite differently. A geneticist, whose focus is on known organisms and their genomes, will very likely have a different view on what constitutes life than an astrophysicist, who considers a more expansive, universal definition.

But beyond that, most of these definitions of life fall short in another, very subtle way: They are based on the origins of life on our planet. This means our hypotheses for what sentient and conscious aliens look like almost always reflect humankind. You only have to look at a Star Trek episode to see it — humanity likes to make the world in our image, which is partially why in sci-fi and fantasy a lot of the “aliens” look a lot like ourselves. (Okay, and because it’s easier to dress a human up as a humanoid alien)…

Cal Tech scientist (and published poet) Alison Koontz explains why none of the 100 definitions of life we have may be accurate away from “home”: “Our concept of life is too Earth-centric — alien life might look totally different.”

* Kurt Vonnegut Jr., Slaughterhouse-Five

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As we confront our chauvinism, we might send speculative birthday greetings to Harlan Jay Ellison; he was born on this date in 1934.  A member (with Philip K. Dick, Samuel Delany, Thomas Disch, Ursula K. LeGuin, and Roger Zelazny) of the American “new wave” science fiction vanguard, Ellison wrote more than 1,700 short stories, novellas, screenplays, comic book scripts, teleplays, essays, and a wide range of criticism covering literature, film, television, and print media.  Some of his best-known work includes the Star Trek episode “The City on the Edge of Forever“, his A Boy and His Dog cycle, and his short stories “I Have No Mouth, and I Must Scream” and “‘Repent, Harlequin!’ Said the Ticktockman“… for which he won many, many awards, including multiple Hugos, Nebulas, and Edgars.

Ellison is also remembered for his outspoken, sometimes combative personality, of which Robert Bloch (the author of Psycho) said “[Ellison is] the only living organism I know whose natural habitat is hot water.”

200px-Harlan_Ellison_at_the_LA_Press_Club_19860712_(cropped_portrait)

source

 

 

 

Written by LW

May 27, 2020 at 1:01 am

“Human DNA spreading out from gravity’s steep well like an oilslick”*…

 

200116-Earth

 

Could the Earth be a life-exporting planet? That’s the curious question examined in a recent paper written by Harvard University astronomers Amir Siraj and Abraham Loeb.

The researchers take a novel twist on the controversial notion of panspermia – the idea, propelled into the mainstream in the early 1970s by astronomers Fred Hoyle and Chandra Wickramasinghe, that life might have started on Earth through microbes arriving from space.

The theory is generally discounted, although eminent astrophysicists such as Stephen Hawking conceded it was at least possible, and a major paper published in 2018 revived the topic big-time.

In their [late December, 2019] paper, Siraj and Loeb reverse the standard assumption about the direction of the microbial journey and ask whether it is possible to that at some point Earth-evolved bacteria could have been propelled away from the planet, possibly to be deposited somewhere else in the Milky Way…

Astronomers suggest microbes might hitch lifts on interstellar asteroids.  More on the hypothesis and the evidence that supports it at “Earth bacteria may have colonised other solar systems.”  Read the underlying paper at arXiv.

* William Gibson, Neuromancer

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As we ponder the polarity of proliferation, we might recall that it was on this date in 1921 that Albert Einstein startled his audience at the Prussian Academy of Sciences in Berlin by suggesting the possibility that the universe could be measured.  His talk, “Geometry and Experience” (text here), applied some results of the relativity theory to conclude that if the real velocities of the stars (as could be actually measured) were less than the calculated velocities, then it would prove that real gravitations’ great distances were smaller than the gravitational distances demanded by the law of Newton.  From that divergence, the finiteness of the universe could be proved indirectly, and could even permit the estimation of its size.

Later that year, Einstein was announced as the 1921 Nobel Laureate in Physics, an award he accepted the following year.

Bildnis Albert Einstein (1879-1955)

Einstein in 1921

source

Happy Birthday, Dante, Mozart, and Lewis Carroll!

 

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