Category Archives: Cosmology

Are FRBs Created by Aliens?

An FRB is an acronym coined by astronomers for fast radio burst. Since recent observations of our cosmos began with super-powerful telescopes only 17 such FRBs have ever been observed. These events last a mere handful of milliseconds but produce the equivalent power of around 100 million suns.

Two theories for these FRBs are relatively mundane. One theory proposes that FRBs are generated by powerful magnetars — highly magnetized, fast-rotating superdense stars. A second theory suggests that a FRB is a created by an especially exotic type of black hole.

And, then, there is a third, more fascinating, theory — that FRBs are the result of alien spaceship propulsion systems.

From the Economist:

Similar unrepeated signals have since been noted elsewhere in the heavens. So far, 17 such “fast radio bursts” (FRBs) have been recognised. They do not look like anything observed before, and there is much speculation about what causes them. One possibility is magnetars—highly magnetised, fast-rotating superdense stars. Another is a particularly exotic sort of black hole, formed when the centrifugal force of a rotating, superdense star proves no longer adequate to the task of stopping that star collapsing suddenly under its own gravity. But, as Manasvi Lingam of Harvard University and Abraham Loeb of the Harvard-Smithsonian Centre for Astrophysics observe, there is at least one further possibility: alien spaceships.

Specifically, the two researchers suggest, in a paper to be published in Astrophysical Journal Letters, that FRBs might be generated by giant radio transmitters designed to push such spaceships around. With the rotation of the galaxies in which these transmitters are located, the transmitter-beams sweep across the heavens. Occasionally, one washes over Earth, producing an FRB.

Read the entire article here.

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Time to Move to Trappist-1

Those bright women and men at NASA have done it again. This time they’ve discovered 7 exoplanets all revolving around the same distant star. The cool news is that on the cosmological distance scale it’s relatively close, only around 40-light years away — a mere 230 trillion miles or so. And, even more fascinating, three of the system’s planets are within the so-called “Goldilocks” habitable zone.

The system is named TRAPPIST-1 (Transiting Planets and Planetesimals Small Telescope). The TRAPPIST telescope in Chile originally discovered 3  exoplanets. Now, using NASA’s Spitzer Space Telescope and the European Southern Observatory’s Very Large Telescope, researchers have upped the total to 7 exoplanets.

I’m ready. Now, just need a spacecraft, and a quick one at that.

From NASA:

NASA’s Spitzer Space Telescope has revealed the first known system of seven Earth-size planets around a single star. Three of these planets are firmly located in the habitable zone, the area around the parent star where a rocky planet is most likely to have liquid water.

The discovery sets a new record for greatest number of habitable-zone planets found around a single star outside our solar system. All of these seven planets could have liquid water – key to life as we know it – under the right atmospheric conditions, but the chances are highest with the three in the habitable zone.

“This discovery could be a significant piece in the puzzle of finding habitable environments, places that are conducive to life,” said Thomas Zurbuchen, associate administrator of the agency’s Science Mission Directorate in Washington. “Answering the question ‘are we alone’ is a top science priority and finding so many planets like these for the first time in the habitable zone is a remarkable step forward toward that goal.”

Read more here.

Image: An illustration of seven Earth-sized planets observed by NASA’s Spitzer Space Telescope around a tiny, nearby, ultra-cool dwarf star called TRAPPIST-1. Three of these planets are firmly in the habitable zone. Courtesy: NASA.

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We Live in a Flat Universe

universe-shape

Cosmologists generally agree that our universe is flat. But how exactly can that be for our 3-dimensional selves and everything else for that matter? Well, first it’s useful to note that the flatness is a property of geometry, and not topology. So, even though it’s flat, the universe could be folded and/or twisted in any number of different, esoteric ways.

From Space:

The universe is flat. But there’s a lot of subtlety packed into that innocent-looking statement. What does it mean for a 3D object to be “flat”? How do we measure the shape of the universe anyway? Since the universe is flat, is that…it? Is there anything else interesting to say?

Oh yes, there is.

First, we need to define what we mean by flat. The screen you’re reading this on is obviously flat (I hope), and you know that the Earth is curved (I hope). But how can we quantify that mathematically? Such an exercise might be useful if we want to go around measuring the shape of the whole entire universe. [The History & Structure of the Universe (Infographic)]

One answer lies in parallel lines. If you start drawing two parallel lines on your paper and let them continue on, they’ll stay perfectly parallel forever (or at least until you run out of paper). That was essentially the definition of a parallel line for a couple thousand years, so we should be good.

Let’s repeat the exercise on the surface of the Earth. Start at the equator and draw a couple parallel lines, each pointing directly north. As the lines continue, they never turn left or right but still end up intersecting at the North Pole. The curvature of the Earth itself caused these initially parallel lines to end up not-so-parallel. Ergo, the Earth is curved.

The opposite of the Earth’s curved shape is a saddle: on that surface, lines that start out parallel end up spreading apart from each other (in swanky mathematical circles this is known as “ultraparallel”).

Read the entire article here.

Image: The shape of the universe depends on its density. If the density is more than the critical density, the universe is closed and curves like a sphere; if less, it will curve like a saddle. But if the actual density of the universe is equal to the critical density, as scientists think it is, then it will extend forever like a flat piece of paper. Courtesy: NASA/WMAP Science team.

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Vera Rubin: Astronomy Pioneer

Vera Rubin passed away on December 26, 2016, aged 88. She was a pioneer in the male-dominated world of astronomy, notable for her original work on dark matter,  galaxy rotation and galaxy clumping.

From Popular Science:

Vera Rubin, who essentially created a new field of astronomy by discovering dark matter, was a favorite to win the Nobel Prize in physics for years. But she never received her early-morning call from Stockholm. On Sunday, she died at the age of 88.

Rubin’s death would sadden the scientific community under the best of circumstances. Countless scientists were inspired by her work. Countless scientists are researching questions that wouldn’t exist if not for her work. But her passing brings another blow: The Nobel Prize cannot be awarded posthumously. The most prestigious award in physics will never be bestowed upon a woman who was inarguably deserving.

In the 1960s and ’70s, Rubin and her colleague Kent Ford found that the stars within spiral galaxies weren’t behaving as the laws of physics dictated that they should. This strange spinning led her and others to conclude that some unseen mass must be influencing the galactic rotation. This unknown matter—now dubbed dark matter—outnumbers the traditional stuff by at least five to one. This is a big deal.

Read more here.

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Spacetime Without the Time

anti-de-sitter-spaceSince they were first dreamed up explanations of the very small (quantum mechanics) and the very large (general relativity) have both been highly successful at describing their respective spheres of influence. Yet, these two descriptions of our physical universe are not compatible, particularly when it comes to describing gravity. Indeed, physicists and theorists have struggled for decades to unite these two frameworks. Many agree that we need a new theory (of everything).

One new idea, from theorist Erik Verlinde of the University of Amsterdam, proposes that time is an emergent construct (it’s not a fundamental building block) and that dark matter is an illusion.

From Quanta:

Theoretical physicists striving to unify quantum mechanics and general relativity into an all-encompassing theory of quantum gravity face what’s called the “problem of time.”

In quantum mechanics, time is universal and absolute; its steady ticks dictate the evolving entanglements between particles. But in general relativity (Albert Einstein’s theory of gravity), time is relative and dynamical, a dimension that’s inextricably interwoven with directions x, y and z into a four-dimensional “space-time” fabric. The fabric warps under the weight of matter, causing nearby stuff to fall toward it (this is gravity), and slowing the passage of time relative to clocks far away. Or hop in a rocket and use fuel rather than gravity to accelerate through space, and time dilates; you age less than someone who stayed at home.

Unifying quantum mechanics and general relativity requires reconciling their absolute and relative notions of time. Recently, a promising burst of research on quantum gravity has provided an outline of what the reconciliation might look like — as well as insights on the true nature of time.

As I described in an article this week on a new theoretical attempt to explain away dark matter, many leading physicists now consider space-time and gravity to be “emergent” phenomena: Bendy, curvy space-time and the matter within it are a hologram that arises out of a network of entangled qubits (quantum bits of information), much as the three-dimensional environment of a computer game is encoded in the classical bits on a silicon chip. “I think we now understand that space-time really is just a geometrical representation of the entanglement structure of these underlying quantum systems,” said Mark Van Raamsdonk, a theoretical physicist at the University of British Columbia.

Researchers have worked out the math showing how the hologram arises in toy universes that possess a fisheye space-time geometry known as “anti-de Sitter” (AdS) space. In these warped worlds, spatial increments get shorter and shorter as you move out from the center. Eventually, the spatial dimension extending from the center shrinks to nothing, hitting a boundary. The existence of this boundary — which has one fewer spatial dimension than the interior space-time, or “bulk” — aids calculations by providing a rigid stage on which to model the entangled qubits that project the hologram within. “Inside the bulk, time starts bending and curving with the space in dramatic ways,” said Brian Swingle of Harvard and Brandeis universities. “We have an understanding of how to describe that in terms of the ‘sludge’ on the boundary,” he added, referring to the entangled qubits.

The states of the qubits evolve according to universal time as if executing steps in a computer code, giving rise to warped, relativistic time in the bulk of the AdS space. The only thing is, that’s not quite how it works in our universe.

Here, the space-time fabric has a “de Sitter” geometry, stretching as you look into the distance. The fabric stretches until the universe hits a very different sort of boundary from the one in AdS space: the end of time. At that point, in an event known as “heat death,” space-time will have stretched so much that everything in it will become causally disconnected from everything else, such that no signals can ever again travel between them. The familiar notion of time breaks down. From then on, nothing happens.

On the timeless boundary of our space-time bubble, the entanglements linking together qubits (and encoding the universe’s dynamical interior) would presumably remain intact, since these quantum correlations do not require that signals be sent back and forth. But the state of the qubits must be static and timeless. This line of reasoning suggests that somehow, just as the qubits on the boundary of AdS space give rise to an interior with one extra spatial dimension, qubits on the timeless boundary of de Sitter space must give rise to a universe with time — dynamical time, in particular. Researchers haven’t yet figured out how to do these calculations. “In de Sitter space,” Swingle said, “we don’t have a good idea for how to understand the emergence of time.”

Read the entire article here.

Image: Image of (1 + 1)-dimensional anti-de Sitter space embedded in flat (1 + 2)-dimensional space. The t1- and t2-axes lie in the plane of rotational symmetry, and the x1-axis is normal to that plane. The embedded surface contains closed timelike curves circling the x1 axis, though these can be eliminated by “unrolling” the embedding (more precisely, by taking the universal cover). Courtesy: Krishnavedala. Wikipedia. Creative Commons Attribution-Share Alike 3.0.

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Asgardia

asgardia-screenshot

With all this earthbound turmoil around us perhaps it’s time to move elsewhere. Asgardia? Well, almost. You may soon be able to become an Asgardian citizen. First the project leaders must convince the United Nations that a satellite to be launched in 2017 deems legal, sovereign status. One catch, though. You’ll still have to reside on Earth.

From the Guardian:

Proposals for the “first nation state in space” have been unveiled by a team of scientists and legal experts, who say the move will foster peace, open up access to space technologies and offer protection for citizens of planet Earth.

Dubbed “Asgardia” after one of the mythical worlds inhabited by the Norse gods, the team say the “new nation” will eventually become a member of the United Nations, with its own flag and anthem devised by members of the public through a series of competitions.

According to the project website, Asgardia “will offer an independent platform
free from the constraint of a land-based country’s laws. It will become a place it in orbit which is truly ‘no man’s land’”.

Initially, it would seem, this new nation will consist of a single satellite, scheduled to be launched next year, with its citizens residing firmly on terra firma.

Speaking to the Guardian through an interpreter, the project lead Igor Ashurbeyli, said: “Physically the citizens of that nation state will be on Earth; they will be living in different countries on Earth, so they will be a citizen of their own country and at the same time they will be citizens of Asgardia.”

“When the number of those applications goes above 100,000 we can officially apply to the UN for the status of state,” he added.

Read the story here.

Image: Screenshot from Asgardia website.

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Europa, Europa

europa-moon

A couple of days ago, September 26, 2016, tens of millions of us tuned in to the gory — and usually devoid of fact — spectacle that is the US Presidential election debate. On the same day, something else rather newsworthy took place; some would say much more important than watching two adults throw puerile nonsense at one another.

NASA has found evidence of water plumes spouting from a subsurface ocean on Europa, Jupiter’s fourth largest moon. The agency used the Hubble Space Telescope to look for signs of plumes as the icy moon transited Jupiter.

This should make for an fascinating encounter when NASA launches a mission in 2020 to examine Europa more closely, especially to investigate whether it could harbor conditions suitable for life.

Image: Trailing hemisphere of Jupiter’s ice-covered satellite, Europa. Europa is about 3,160 kilometers (1,950 miles) in diameter, or about the size of Earth’s moon. Courtesy: NASA/JPL/DLR (Deutsche Forschungsanstalt fuer Luftund Raumfahrt e.V., Berlin, Germany).

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Tabby’s Star

KIC_8462852_in_IR_and_UV

Tabby’s Star, officially known by the cryptic notation KIC 8462852 is a very odd object. The star is around 1,500 light years from Earth, and has been puzzling astronomers with its strangely fluctuating brightness. Recent analysis shows that is even weirder than first thought, which has scientists baffled. Could the observations be caused by a storm of wildly orbiting comets? Or, much more compelling (for SciFi buffs), could it be an alien megastructure periodically shrouding the star?

From Space:

KIC 8462852 was observed by NASA’s Kepler mission and has become infamous for its bizarre and unprecedented transit signal that was flagged by citizen scientists. Now new research of precision Kepler observations has shown that the overall brightness of the star — unofficially named “Tabby’s Star” after astronomer Tabetha S. Boyajian who discovered the peculiar signal — has been decreasing, which poses a new and confusing problem for astronomers trying to understand what the heck is going on.

Kepler’s prime mission is to look for small worlds that pass in front of their parent stars causing a slight dimming of starlight. The “transit method” has been hugely successful and has confirmed well over 2,000 planets orbiting other stars in our galaxy.

But Tabby’s Star’s transit signal, otherwise known as a “light-curve”, stopped astronomers in their tracks. Something passed in front of it, dimming its starlight a whopping 20 percent and other jumbled transit signals revealed that something wasn’t quite right with this particular star. Then, in an interview with The Atlantic, Penn State University astronomer Jason Wright speculated that the signal could be indicative of an “alien megastructure” that’s in the process of being built. You can catch up on the controversy surrounding the anomalous signal in my recent Discovery News article “Closing In on ‘Alien Megastructure’ Clues.”

So, in an effort to track down a rational explanation, Bradley Schaefer from Louisiana State University decided to study historical observations of KIC 8462852 in astronomical photographic plates from the past century to see if the star exhibited any bizarre fluctuations in brightness in the past. Sure enough, yes, the star is a bit of an oddball and has shown a long-term decreasing trend in brightness! Since the 19th Century, its brightness has decreased steadily by nearly 20 percent.

Now, astronomers Ben Montet (from Caltech) and Joshua Simon (from the Carnegie Institute) have released a paper to the arXiv preprint service detailing recent Kepler observations of KIC 8462852 since the space telescope was launched in 2009. Although the dataset for this time period is comparatively small, Monet and Simon found yet another surprise.

In the 4 years of Kepler’s primary mission, the star showed an unprecedented dimming of 3.5 percent. So not only did Kepler detect transient dips in brightness of up to 20 percent, there also seems to be a very definite downward trend in brightness throughout our observational history of the star.

No matter how you slice it, this is strange.

Read the entire story here.

Image: Tabby’s Star, KIC 8462852, in infrared (2MASS survey) and ultraviolet (GALEX). Courtesy: IPAC/NASA (Infrared), STScI/NASA (Ultraviolet). Public Domain.

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Osiris-Rex and Bennu

Osiris-Rex_Bennu

You might be mistaken for thinking Osiris-Rex and Bennu are the names of two rather exotic dogs. No.

Bennu is a 1,500 foot wide space rock, which circles the Sun at around 60,000 mph. OSIRIS-REx is the space probe which aims to catch the near-Earth asteroid in 2018 and return samples back to Earth in 2023. NASA is scheduled to launch OSIRIS-REx from aboard an Atlas V rocket on September 8, 2016, from Cape Canaveral in Florida. Follow NASA’s asteroid mission here.

In case you were wondering, as is NASA’s wont, OSIRIS-REx is of course a convoluted acronym for the Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer spacecraft.

From the Guardian:

At Cape Canaveral air force station on the Florida coast stands an Atlas V rocket bearing the Osiris-Rex probe, Nasa’s first hope to smash-and-grab material from a speeding asteroid and bring it safely back to Earth.

The size of a transit van, the two-tonne spacecraft is set to blast off Thursday night on a seven-year mission to a 500m-wide ball of rubble called Bennu, which circles the sun at more than 100,000km per hour.

The probe is the third of Nasa’s ambitious New Frontiers missions. It follows on the heels of the New Horizons spacecraft, which last year beamed home stunning images from Pluto, and the Juno spacecraft, which arrived at Jupiter in July.

In returning a pile of asteroid to Earth, scientists hope to learn more about the source of water in the solar system and the origins of organic molecules from which life first arose. But getting their hands on pristine asteroid will also give researchers fresh clues about how to mine the bodies for valuable materials, and defend against wayward space rocks that may one day threaten our planet.

The mission has a title that is unwieldy even for the US space agency. Osiris-Rex stands for Origins, Spectral Interpretation, Resource Identification and Security-Regolith Explorer. “It is a mouthful,” said Ed Beshore, deputy principal investigator on the mission at Arizona State University. “But the name really does speak to our principal mission objectives.”

Bennu orbits the sun on a similar path to Earth. Classified as a “potentially hazardous asteroid”, it swings close to the Earth – in cosmic terms, at least – once every six years. The nearest encounter scientists can predict is slated for 2135, when the coal-black space rock will hurtle between Earth and the moon at a distance of 300,000km.

One major question the mission will ask is how sunlight affects the orbits of asteroids. As they spin close to the sun asteroids are constantly heating up and cooling down. The heat the asteroid re-emits to space provides a minuscule thrust which over time can alter its course. But the effect is hard to quantify. “Often when we look at asteroids that may be a hazard to Earth, the limiting factor in predicting the orbit is this process called the Yarkovsky effect,” said Beshore. “We’d like to understand that and measure it much more precisely when we’re at Bennu and in doing so improve our predictive accuracy for other asteroids that may represent a future threat to Earth.”

Osiris-Rex aims to catch up with Bennu in August 2018 and spend two years mapping the surface. When mission scientists find a good spot, it will swoop down, blast the asteroid with a powerful jet of nitrogen, and collect dislodged material with a robotic arm. Once the material is safely aboard, the spacecraft will retreat and later send it home in a capsule due to land via parachute in the Utah desert in 2023.

Read the whole story here.

Image: Artist concept of OSIRIS-REx probe traveling to near-Earth asteroid Bennu on a sample return mission. Courtesy: NASA.

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Can We Move There?

Pale Red Dot is an international search for an Earth-like exoplanet around the closest star to us, Proxima Centauri. It will use HARPS, attached to ESO’s 3.6-metre telescope at La Silla Observatory, as well as the Las Cumbres Observatory Global Telescope Network (LCOGT) and the Burst Optical Observer and Transient Exploring System (BOOTES). It will be one of the few outreach campaigns allowing the general public to witness the scientific process of data acquisition in modern observatories. The public will see how teams of astronomers with different specialities work together to collect, analyse  and interpret data, which may or may not be able to confirm the presence of an Earth-like planet orbiting our nearest neighbour . The outreach campaign consists of blog posts and social media updates on the Pale Red Dot Twitter account and using the hashtag #PaleRedDot. For more information visit the Pale Red Dot website: http://www.palereddot.org

I’ve been toying with the idea of uprooting and moving to Canada should a certain orange-haired bigot win the US presidential election. But, no offense to Canadians, scientists have just discovered an Earth-like planet a mere 4.25 light-years away, our nearest celestial neighbor.

Can anyone convince Elon Musk (of SpaceX) to get cracking on a suitable spacecraft that will get us there, or at least help us leave, before November 8, 2016? Forget Mars, Proxima Centauri here I come!

From Space.com

The star closest to the sun hosts a planet that may be very much like Earth, a new study reports.

Astronomers have discovered a roughly Earth-size alien world around Proxima Centauri, which lies just 4.2 light-years from our own solar system. What’s even more exciting, study team members said, is that the planet, known as Proxima b, circles in the star’s “habitable zone” — the range of distances at which liquid water could be stable on a world’s surface.

“We hope these findings inspire future generations to keep looking beyond the stars,” lead author Guillem Anglada-Escude, a physics and astronomy lecturer at Queen Mary University of London, said in a statement.”The search for life on Proxima b comes next.” [In Pictures: The Discovery of Planet Proxima b]

The discovery of Proxima b was a long time in the making.

Astronomers have been hunting intensively for planets around Proxima Centauri for more 15 years, using instruments such as the Ultraviolet and Visual Echelle Spectrograph (UVES) and the High Accuracy Radial velocity Planet Searcher (HARPS), both of which are installed on telescopes run by the European Southern Observatory in Chile.

UVES, HARPS and other instruments like them allow researchers to detect the slight wobbles in a star’s movement caused by the gravitational tugs of orbiting planets.

Astronomers found hints of such a wobble back in 2013, but the signal was not convincing, Anglada-Escude said. So he and a number of other researchers launched a campaign to ferret out the planet. They called this effort the Pale Red Dot — a nod to Carl Sagan’s famous description of Earth as a “pale blue dot,” and the fact that Proxima Centauri is a small, dim star known as a red dwarf.

The Pale Red Dot team focused HARPS on Proxima Centauri every night from Jan. 19, 2016, through March 31 of this year. After they combined this new data with UVES observations from 2000 through 2008 and HARPS observations from 2005 through early 2014, the signal of a possible planet came through loud and clear.

Then, after analyzing observations of the star’s brightness made by several other telescopes, Anglada-Escude and his colleagues ruled out the possibility that this signal could be caused by the variable activity of Proxima Centauri.

“The conclusion: We have found a planet around Proxima Centauri,” Anglada-Escude said Tuesday (Aug. 23) during a news conference.

Read the entire story here.

Image: Pale Red Dot, an international search for an Earth-like exoplanet around the closest star to us, Proxima Centauri. It will use HARPS, attached to ESO’s 3.6-metre telescope at La Silla Observatory, as well as the Las Cumbres Observatory Global Telescope Network (LCOGT) and the Burst Optical Observer and Transient Exploring System (BOOTES). It will be one of the few outreach campaigns allowing the general public to witness the scientific process of data acquisition in modern observatories. The public will see how teams of astronomers with different specialities work together to collect, analyse and interpret data, which may or may not be able to confirm the presence of an Earth-like planet orbiting our nearest neighbour. The outreach campaign consists of blog posts and social media updates on the Pale Red Dot Twitter account and using the hashtag #PaleRedDot. For more information visit the Pale Red Dot website : http://www.palereddot.org. Courtesy: ESO/Pale Red Dot – http://www.eso.org/public/images/ann16002a/

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The Accelerated Acceleration

Dark_Energy

Until the mid-1990s accepted scientific understanding of the universe held that the cosmos was expanding. Scientists have accepted this since 1929 when Edwin Hubble‘s celestial observations showed that distant galaxies were all apparently moving away from us.

But, in 1998 two independent groups of cosmologists made a startling finding. The universe was not only expanding, its expansion was accelerating. Recent studies show that this acceleration in the fabric of spacetime is actually faster than first theorized and observed.

And, nobody knows why. This expansion, indeed the accelerating expansion, remains one of our current great scientific mysteries.

Cosmologists, astronomers and theoreticians of all stripes have proposed no shortage of possible explanations. But, there is still scant observational evidence to support any of the leading theories. The most popular revolves around the peculiar idea of dark energy.

From Scientific American:

Our universe is flying apart, with galaxies moving away from each other faster each moment than they were the moment before. Scientists have known about this acceleration since the late 1990s, but whatever is causing it—dubbed dark energy—remains a mystery. Now the latest measurement of how fast the cosmos is growing thickens the plot further: The universe appears to be ballooning more quickly than it should be, even after accounting for the accelerating expansion caused by dark energy.

Scientists came to this conclusion after comparing their new measurement of the cosmic expansion rate, called the Hubble constant, to predictions of what the Hubble constant should be based on evidence from the early universe. The puzzling conflict—which was hinted at in earlier data and confirmed in the new calculation—means that either one or both of the measurements are flawed, or that dark energy or some other aspect of nature acts differently than we think.

“The bottom line is that the universe looks like it’s expanding about eight percent faster than you would have expected based on how it looked in its youth and how we expect it to evolve,” says study leader Adam Riess of the Space Telescope Science Institute in Baltimore, Md. “We have to take this pretty darn seriously.” He and his colleagues described their findings, based on observations from the Hubble Space Telescope, in a paper submitted last week to the Astrophysical Journal and posted on the preprint server arXiv.

One of the most exciting possibilities is that dark energy is even stranger than the leading theory suggests. Most observations support the idea that dark energy behaves like a “cosmological constant,” a term Albert Einstein inserted into his equations of general relativity and later removed. This kind of dark energy would arise from empty space, which, according to quantum mechanics, is not empty at all, but rather filled with pairs of “virtual” particles and antiparticles that constantly pop in and out of existence. These virtual particles would carry energy, which in turn might exert a kind of negative gravity that pushes everything in the universe outward.

Read the entire story here.

Image: The universe’s accelerated expansion. Courtesy: NASA and ESA.

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The Transit of Dione

Dione-transit-of-Saturn

This gorgeous image of Saturn’s moon Dione as it transits the gas giant was snapped by the Cassini spacecraft on May 27, 2015. For more beautiful views of the stunning ringed planet and its curious moons visit NASA’s Cassini mission site.

Image: Saturn’s moon Dione transits the giant ringed planet. Courtesy: NASA/JPL-Caltech/Space Science Institute in Boulder, Colorado.

 

 

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The Case For Planet Nine

Planet_nine_artistic-impression

First, let me say that Pluto should never have been downgraded to the status of “dwarf planet”. The recent (and ongoing) discoveries by NASA’s New Horizons probe show Pluto’s full, planetary glory: kilometer high mountains, flowing glaciers, atmospheric haze, organic compounds, complex and colorful landforms. So, in my mind Pluto still remains as the ninth planet in our beautiful solar system.

However, many astronomers have moved on and are getting excited over the possibility of a new Planet Nine. The evidence for its existence is mounting and comes mostly from models that infer the presence of a massive object far-beyond Pluto, which is influencing the orbits of asteroids and even some of the outer planets.

From Scientific American:

The hunt is on to find “Planet Nine”—a large undiscovered world, perhaps 10 times as massive as Earth and four times its size—that scientists think could be lurking in the outer solar system. After Konstantin Batygin and Mike Brown, two planetary scientists from the California Institute of Technology, presented evidence for its existence this January, other teams have searched for further proof by analyzing archived images and proposing new observations to find it with the world’s largest telescopes.

Just this month, evidence from the Cassini spacecraft orbiting Saturn helped close in on the missing planet. Many experts suspect that within as little as a year someone will spot the unseen world, which would be a monumental discovery that changes the way we view our solar system and our place in the cosmos. “Evidence is mounting that something unusual is out there—there’s a story that’s hard to explain with just the standard picture,” says David Gerdes, a cosmologist at the University of Michigan who never expected to find himself working on Planet Nine. He is just one of many scientists who leapt at the chance to prove—or disprove—the team’s careful calculations.

Batygin and Brown made the case for Planet Nine’s existence based on its gravitational effect on several Kuiper Belt objects—icy bodies that circle the sun beyond Neptune’s orbit. Theoretically, though, its gravity should also tug slightly on the planets.* With this in mind, Agnès Fienga at the Côte d’Azur Observatory in France and her colleagues checked whether a theoretical model (one that they have been perfecting for over a decade) with the new addition of Planet Nine could better explain slight perturbations seen in Saturn’s orbit as observed by Cassini.* Without it, the other seven planets in the solar system, 200 asteroids and five of the most massive Kuiper Belt objects cannot perfectly account for it.* The missing puzzle piece might just be a ninth planet.

So Fienga and her colleagues compared the updated model, which placed Planet Nine at various points in its hypothetical orbit, with the data. They found a sweet spot—with Planet Nine 600 astronomical units (about 90 billion kilometers) away toward the constellation Cetus—that can explain Saturn’s orbit quite well.* Although Fienga is not yet convinced that she has found the culprit for the planet’s odd movements, most outside experts are blown away.* “It’s a brilliant analysis,” says Greg Laughlin, an astronomer at Lick Observatory, who was not involved in the study. “It’s completely amazing that they were able to do that so quickly.” Gerdes agrees: “That’s a beautiful paper.”

The good news does not end there. If Planet Nine is located toward the constellation Cetus, then it could be picked up by the Dark Energy Survey, a Southern Hemisphere observation project designed to probe the acceleration of the universe. “It turns out fortuitously that the favored region from Cassini’s data is smack dab in the middle of our survey footprint,” says Gerdes, who is working on the cosmology survey.* “We could not have designed our survey any better.” Although the survey was not planned to search for solar system objects, Gerdes has discovered some (including one of the icy objects that led Batygin and Brown to conclude Planet Nine exists in the first place).

Read the entire article here.

Image: Artist’s impression of Planet Nine as an ice giant eclipsing the central Milky Way, with a star-like Sun in the distance. Neptune’s orbit is shown as a small ellipse around the Sun. Courtesy: Tomruen, nagualdesign / Wikipedia. Creative Commons.

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Your Ticket to the Past: Tipler Cylinder

So, you want to travel back in time? Here’s the solution. But first forget the tricked-out DeLorean and H.G. Wells’ victorian time machine. What you need is a Tipler Cylinder. Let’s begin with the ingredients if you are inclined to construct your very own cylinder.

  1. Take a mass of about 10 times that of the Sun.
  2. Compress and fashion the mass into an infinitely long, spaghetti-like cylinder.
  3. Spin the cylinder, along its longitudinal axis, at least up to several billion revolutions per minute.

Once you’ve  done this all you need in a craft able to spiral around the cylinder — without getting crushed by gravity — to make use of its frame-dragging of spacetime. Voila! Do this correctly, and you might well emerge billions of years from where you began. But, you’ll be in the past, of course.

Read more about the Tipler Cylinder here.

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Searching for Signs of Life

Gliese 581 c

Surely there is intelligent life somewhere in the universe. Cosmologists estimate that the observable universe contains around 1,000,000,000,000,000,000,000,000 planets. And, they calculate that our Milky Way galaxy alone contains around 100 billion planets that are hospitable to life (as we currently know it).

These numbers boggle the mind and beg a question: how do we find evidence for life beyond our shores? The decades long search for extraterrestrial intelligence (SETI) pioneered the use of radio telescope observations to look for alien signals from deep space. But, the process has remained rather rudimentary and narrowly focused. The good news now is that astronomers and astrobiologists have a growing toolkit of techniques that allow for much more sophisticated detection and analysis of the broader signals of life — not just potential radio transmissions from an advanced alien culture.

From Quanta:

Huddled in a coffee shop one drizzly Seattle morning six years ago, the astrobiologist Shawn Domagal-Goldman stared blankly at his laptop screen, paralyzed. He had been running a simulation of an evolving planet, when suddenly oxygen started accumulating in the virtual planet’s atmosphere. Up the concentration ticked, from 0 to 5 to 10 percent.

“Is something wrong?” his wife asked.

“Yeah.”

The rise of oxygen was bad news for the search for extraterrestrial life.

After millennia of wondering whether we’re alone in the universe — one of “mankind’s most profound and probably earliest questions beyond, ‘What are you going to have for dinner?’” as the NASA astrobiologist Lynn Rothschild put it — the hunt for life on other planets is now ramping up in a serious way. Thousands of exoplanets, or planets orbiting stars other than the sun, have been discovered in the past decade. Among them are potential super-Earths, sub-Neptunes, hot Jupiters and worlds such as Kepler-452b, a possibly rocky, watery “Earth cousin” located 1,400 light-years from here. Starting in 2018 with the expected launch of NASA’s James Webb Space Telescope, astronomers will be able to peer across the light-years and scope out the atmospheres of the most promising exoplanets. They will look for the presence of “biosignature gases,” vapors that could only be produced by alien life.

They’ll do this by observing the thin ring of starlight around an exoplanet while it is positioned in front of its parent star. Gases in the exoplanet’s atmosphere will absorb certain frequencies of the starlight, leaving telltale dips in the spectrum.

As Domagal-Goldman, then a researcher at the University of Washington’s Virtual Planetary Laboratory (VPL), well knew, the gold standard in biosignature gases is oxygen. Not only is oxygen produced in abundance by Earth’s flora — and thus, possibly, other planets’ — but 50 years of conventional wisdom held that it could not be produced at detectable levels by geology or photochemistry alone, making it a forgery-proof signature of life. Oxygen filled the sky on Domagal-Goldman’s simulated world, however, not as a result of biological activity there, but because extreme solar radiation was stripping oxygen atoms off carbon dioxide molecules in the air faster than they could recombine. This biosignature could be forged after all.

The search for biosignature gases around faraway exoplanets “is an inherently messy problem,” said Victoria Meadows, an Australian powerhouse who heads VPL. In the years since Domagal-Goldman’s discovery, Meadows has charged her team of 75 with identifying the major “oxygen false positives” that can arise on exoplanets, as well as ways to distinguish these false alarms from true oxygenic signs of biological activity. Meadows still thinks oxygen is the best biosignature gas. But, she said, “if I’m going to look for this, I want to make sure that when I see it, I know what I’m seeing.”

Meanwhile, Sara Seager, a dogged hunter of “twin Earths” at the Massachusetts Institute of Technology who is widely credited with inventing the spectral technique for analyzing exoplanet atmospheres, is pushing research on biosignature gases in a different direction. Seager acknowledges that oxygen is promising, but she urges the astrobiology community to be less terra-centric in its view of how alien life might operate — to think beyond Earth’s geochemistry and the particular air we breathe. “My view is that we do not want to leave a single stone unturned; we need to consider everything,” she said.

As future telescopes widen the survey of Earth-like worlds, it’s only a matter of time before a potential biosignature gas is detected in a faraway sky. It will look like the discovery of all time: evidence that we are not alone. But how will we know for sure?

Read the entire article here.

Image: Artist’s Impression of Gliese 581 c, the first terrestrial extrasolar planet discovered within its star’s habitable zone. Courtesy: Hervé Piraud, Latitude0116, Xhienne. Creative Commons Attribution 2.5.

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A Trip to Titan

titanNASA is advertising its upcoming space tourism trip to Saturn’s largest moon Titan with this gorgeous retro poster.

Just imagine rowing across Titan’s lakes and oceans, and watching Saturn set below the horizon. So, dump that planned cruise down the Danube and hike to your local travel agent before all the seats are gone. But, before you purchase a return ticket keep in mind the following:

Frigid and alien, yet similar to our own planet billions of years ago, Saturn’s largest moon, Titan, has a thick atmosphere, organic-rich chemistry and a surface shaped by rivers and lakes of liquid ethane and methane. Cold winds sculpt vast regions of hydrocarbon-rich dunes. There may even be cryovolcanoes of cold liquid water. NASA’s Cassini orbiter was designed to peer through Titan’s perpetual haze and unravel the mysteries of this planet-like moon.
Image: Titan poster. Courtesy of NASA/JPL.
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Another Glorious Hubble Image

This NASA/ESA Hubble Space Telescope image shows the spiral galaxy NGC 4845, located over 65 million light-years away in the constellation of Virgo (The Virgin). The galaxy’s orientation clearly reveals the galaxy’s striking spiral structure: a flat and dust-mottled disc surrounding a bright galactic bulge. NGC 4845’s glowing centre hosts a gigantic version of a black hole, known as a supermassive black hole. The presence of a black hole in a distant galaxy like NGC 4845 can be inferred from its effect on the galaxy’s innermost stars; these stars experience a strong gravitational pull from the black hole and whizz around the galaxy’s centre much faster than otherwise. From investigating the motion of these central stars, astronomers can estimate the mass of the central black hole — for NGC 4845 this is estimated to be hundreds of thousands times heavier than the Sun. This same technique was also used to discover the supermassive black hole at the centre of our own Milky Way — Sagittarius A* — which hits some four million times the mass of the Sun (potw1340a). The galactic core of NGC 4845 is not just supermassive, but also super-hungry. In 2013 researchers were observing another galaxy when they noticed a violent flare at the centre of NGC 4845. The flare came from the central black hole tearing up and feeding off an object many times more massive than Jupiter. A brown dwarf or a large planet simply strayed too close and was devoured by the hungry core of NGC 4845.

The Hubble Space Telescope captured this recent image of spiral galaxy NGC 4845. The galaxy lies around 65 million light-years from Earth, but it still presents a gorgeous sight. NGC 4845’s glowing center hosts a supermassive, and super hungry, black hole.

Thanks NASA, but I just wish you would give these galaxies more memorable names.

Image: NASA/ESA Hubble Space Telescope image shows the spiral galaxy NGC 4845, located over 65 million light-years away in the constellation of Virgo. Courtesy: ESA/Hubble & NASA and S. Smartt (Queen’s University Belfast).

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A Gravitational Wave Comes Ashore

ligo-gravitational-waves-detection

On February 11, 2016, a historic day for astronomers the world over, scientists announced a monumental discovery, which was made on September 14, 2015! Thank you LIGO, the era of gravitational wave (G-Wave) astronomy has begun.

One hundred years after a prediction from Einstein’s theory of general relativity scientists have their first direct evidence of gravitational waves. These waves are ripples in the fabric of spacetime itself rather than the movement of fields and particles, such as from electromagnetic radiation. These ripples show up when gravitationally immense bodies warp the structure of space in which they sit, such as through collisions or acceleration.

ligo-hanford-aerial

As you might imagine for such disturbances to be observed here on Earth over distances in the tens to hundreds of millions, of light-years requires not only vastly powerful forces at one end but immensely sensitive instruments at the other. In fact the detector credited with discovery in this case is the Laser Interferometer Gravitational-Wave Observatory, or LIGO. It is so sensitive it can detect a change in length of its measurement apparatus — infra-red laser beams — 10,000 times smaller than the width of a proton. LIGO is operated by Caltech and MIT and supported through the U.S. National Science Foundation.

Prof Kip Thorne, one of the founders of LIGO, said that until now, astronomers had looked at the universe as if on a calm sea. This is now changed. He adds:

“The colliding black holes that produced these gravitational waves created a violent storm in the fabric of space and time, a storm in which time speeded up and slowed down, and speeded up again, a storm in which the shape of space was bent in this way and that way.”

And, as Prof Stephen Hawking remarked:

“Gravitational waves provide a completely new way of looking at the universe. The ability to detect them has the potential to revolutionise astronomy. This discovery is the first detection of a black hole binary system and the first observation of black holes merging.”

Congratulations to the many hundreds of engineers, technicians, researchers and theoreticians who have collaborated on this ground-breaking experiment. Particular congratulations go to LIGO’s three principal instigators: Rainier Weiss, Kip Thorne, and Ronald Drever.

This discovery paves the way for deeper understanding of our cosmos and lays the foundation for a new and rich form of astronomy through gravitational observations.

Galileo’s first telescopes opened our eyes to the visual splendor of our solar system and its immediate neighborhood. More recently, radio-wave, x-ray and gamma-ray astronomy have allowed us to discover wonders further afield: star-forming nebulae, neutron stars, black holes, active galactic nuclei, the Cosmic Microwave Background (CMB). Now, through LIGO and its increasingly sensitive descendants we are likely to make even more breathtaking discoveries, some of which, courtesy of gravitational waves, may let us peer at the very origin of the universe itself — the Big Bang.

How brilliant is that!

Image 1: The historic detection of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO) is shown in this plot during a press conference in Washington, D.C. on Feb. 11, 2016.Courtesy: National Science Foundation.

Image 2: LIGO Laboratory operates two detector sites 1,800 miles apart: one near Hanford in eastern Washington, and another near Livingston, Louisiana. This photo shows the Hanford detector. Courtesy of LIGO Caltech.

 

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See, Earth is at the Center of the Cosmos

A single image of the entire universe from 2012 has been collecting lots of attention recently. Not only is it beautiful, it shows the Earth and our solar system clearly in the correct location — at the rightful center!

Some seem to be using this to claim that the circa 2,000 year old, geo-centric view of the cosmos must be right.

Observable_universe_logarithmic_illustration

Well, sorry creationists, flat-earthers, and followers of Ptolemy, this gorgeous image is a logarithmic illustration.

Image: Artist’s logarithmic scale conception of the observable universe with the Solar System at the center, inner and outer planets, Kuiper belt, Oort cloud, Alpha Centauri, Perseus Arm, Milky Way galaxy, Andromeda galaxy, nearby galaxies, Cosmic Web, Cosmic microwave radiation and Big Bang’s invisible plasma on the edge. Courtesy: Pablo Carlos Budassi / Wikipedia.

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