[PHOTO] B&J Trading Company, 378 Spadina Avenue

B&J Trading Company, located at 378 Spadina Avenue on the corner of Spadina and Baldwin (west side of the street) looks good at night.

(I prefer the second. You?)

[LINK] Two Centauri Dreams notes on the search for extraterrestrial intelligence

The two latest posts at Centauri Dreams, both by Paul Gilster, examines the search for extraterrestrial intelligence and the impact of new techniques and technologies. What's possible?

The first is "Is our civilization detectable?". The new Square Kilometre Array, a collection of hundreds of small radio telescopes scattered across the Southern Hemisphere--South Africa, Australia, New Zealand--will be very sensitive. Could it pick up signals from a civilization like ours?

People sometimes assume that stray signals would be easily snared at interstellar distances, but we’re learning that it would take a mammoth installation to make such a catch. The film Contact, made from Sagan’s novel of the same name, uses the wonderful device of a broadcast returned to us, a transmission from the 1936 Olympics in Berlin. Receiving such a signal parroted back to us would surely flag the detection of an extraterrestrial civilization and cause researchers to begin the necessary work to look for embedded information inside it.

The people behind the Square Kilometer Array talk about the ability of this instrument, once its vast telescopic resources are in place and connected to powerful computing facilities, to pick up something as weak as the extraterrestrial equivalent of an airport radar around another star. It’s a fantastic prospect, implying our ability to add a new layer to our existing SETI investigations. Is it possible that instead of scanning the skies for beacons, we might simply begin to pick up the extraneous signals of a civilization going about its daily life? The goal is energizing, but hearing claims about extraterrestrial detections always makes me uneasy.

Back in late 2010, James Benford discussed leakage radiation at a meeting of the Royal Society in Britain, asking whether the kind of installations we currently have on Earth could detect signals this weak if sent from a nearby star. It turns out a typical radio telescope like the Parkes instrument in Australia, if located near Alpha Centauri, would not be able to detect our TV transmissions at all. Benford pointed out that signal information is transmitted in bands on each side of the central frequency and that broadcast antennae aim their transmitted power mostly toward the surface. Signals that get into space are not coherent and are unlikely to be noted.

The second, "All Quiet Around Gliese 581", reports on the results of a proof-of-concept scan of this nearby red dwarf star and its planets.

We’ve been considering the possibilities growing out of the Square Kilometer Array for SETI purposes, prompting a number of readers, Adam Crowl being the first, to send along a new paper on using Very Long Baseline Interferometry in a targeted SETI search. Hayden Rampadarath and colleagues at the International Centre for Radio Astronomy Research (Perth, Australia) intend the paper to be a foundational document for the use of VLBI in future SETI projects including those at the SKA. The results show great promise for the technique.

With VLBI, combining signals from multiple telescopes allows us to emulate a single instrument the size of the maximum separation between the telescopes, which could be hundreds to thousands of kilometers. Interestingly, there has been little application of VLBI techniques in SETI, although the SETI-Italia project using the VLBI Medicina telescope is active and the SETI Institute has been studying interferometric techniques at frequencies between 1200 and 1750 MHz. What Rampadarath and colleagues have done is to target the widely studied red dwarf Gliese 581, using observations at 1230-1544 MHz made with the Australian Long Baseline Array, which includes three radio telescopes spaced widely in New South Wales.

It’s a good choice of target because Gliese 581 is a multi-planet system with at least one planet that looks to be on the edge of the habitable zone. With Kepler’s investigations of thousands of planetary candidates ongoing, we’re beginning to pick out high-value targets like this, defined as planets where liquid water could exist on the surface and life might arise. Gl 581 is not one of the Kepler worlds, but it does present us in the form of Gl581d with a super-Earth with an orbital period of 83 days that according to at least one recent study may offer habitable conditions. The existence of another possible habitable zone planet, Gl581g, now appears unlikely.

The Perth team observed Gl581 for eight hours using the stations of the Long Baseline Array. The result: 200 narrow-band and 22 broadband candidate signals were examined, most or all of which are thought to have been caused by Australian space to Earth geostationary satellites. No evidence for signals from the region of Gl581 emerges. The result is hardly a surprise, but the good news is that this pilot study demonstrates that Very Long Baseline Interferometry makes what the authors call ‘an ideal technique for targeted SETI.’

[LINK] "Is it too late for first contact with aliens?"

Esther Inglis-Arkell's io9 essay does a nice job of outlining the emerging question on the search for extraterrestrial intelligence: why haven't we found them yet?

My gut instinct is that we've been missing some basic information and that, in the near future, we may find out what this information is and what the answer to the question is, but as everyone knows gut instincts are hardly things worthy of making bets on, especially with so little information and such huge stakes.

Every scientific breakthrough has taken time to get going. Knowledge and technology needs to slowly accrue over time until a tipping point is reached. But in some cases, time just isn't a factor. Can we say that some things will never happen because they haven't happened yet?

Case in point: first contact with aliens. Wouldn't it have happened already if it was going to?

There's a famous equation, the Drake Equation, that attempts to figure out exactly how likely it is that humans will make contact with alien life. The equation is a long string of variables. Some variables represent the rate of planet formation and the rate at which life and civilizations evolve. Some variables represent the fraction of planets that can support life, and the fraction of civilizations that develop technology that can competently look for alien civilizations in the universe. The last variable represents how long those societies can last, before they collapse.

In the past, the Drake Equation has been used by doomsayers, who were worried about global nuclear war. The fact that people haven't seen anything yet had to mean, they thought, that societies which develop sufficiently high levels of technology always destroy themselves. Although the apocalyptians still make a decent argument, the fact that the globe hasn't been reduced to ash yet makes it just possible that, instead, we're just coming up against some hard physical limits.

Obviously, the equation is more a thought experiment than an actual solution. At the time that Frank Drake, a astrophysics professor at UC Santa Cruz, thought it up, the world didn't even know that there were more than nine planets (Pluto was still in play). Every single value was an estimate, and continues to be an estimate. Still, the estimates make you wonder. There have to be billions of other Earths out there. What does it mean that no one has contacted us?

Is it too late for first contact with aliens? There's a Catch-22 built into the equation. Because we haven't made contact, the only thing on which we can base the rate of the development of life and technology, from a single cell to SETI, is the Earth. In order to understand properly whether the Earth is slow or fast by universal standards, we have to be able to compare ourselves to other planets — which we can't do until we make contact.

The search for alien life is still in its infancy here. Let's say the Earth holds a relatively fast-developing civilization. Our planet is about four billion years old, a third as old as the universe, so if the other worlds out there are developing at a rate of less than one third Earth speed, it's doubtful they'd be able to receive Earth's signals, let alone contact us back. If, on the other hand, they're developing faster, they should have found us by now. Or we should have found them.

The only thing that could keep them doing so is if it's physically impossible, given the size of the universe, the number of worlds that can develop intelligent life, and the distance between them, to make contact contact other civilizations. Ever.

Saying that, in an infinite universe, if something can happen, it has to happen to us, is verging on lottery-ticket logic. Just because there are a lot of chances for something, doesn't mean that anyone actually has to hit it big. Random chance always plays a part. But there is a case to be made that, if we didn't find intelligent alien life waving a flag and trying to contact us soon after we started looking, we very well might never find it at all.

[BLOG-LIKE POSTING] On the impending union of the Milky Way and Andromeda galaxies

Our Milky Way Galaxy and the Andromeda Galaxy 2.6 million light years away from us are the two largest components of the Local Group, a cluster of more than four dozen galaxies and assorted debris bound by mutual gravitation. (It's still open to debate whether the Milky Way Galaxy is the more massive of the two, or whether the most massive is the Andromeda Galaxy. The most recent estimates of star numbers and total mass I've seen suggest that the Andromeda Galaxy might have more, but less massive, stars than our galaxy, and that the two galaxies are roughly equal in mass.)

For some time, measurements of the movement of the Andromeda Galaxy relative to our own have suggested that the two largest galaxies in the Local Group are set to collide. What was unknown was the way in which it would collide. Would it be a head-on collision, or something more glancing, or perhaps even a near miss? Universe Today's Nancy Atkinson explains that it's going to be a direct collision.

Astronomers have known for years that our Milky Way and its closest neighbor, the Andromeda galaxy, (a.k.a M31) are being pulled together in a gravitational dance, but no one was sure whether the galaxies would collide head-on or glide past one another. Precise measurements from the Hubble Space Telescope have now confirmed that the two galaxies are indeed on a collision course, headed straight for a colossal cosmic collision.

No need to panic for the moment, as this is not going to happen for another four billion years. And while astronomers say it is likely the Sun will be flung into a different region of our galaxy, Earth and the solar system will probably just go along for the ride and are in no danger of being destroyed.

“In the ‘worst-case-scenario’ simulation, M31 slams into the Milky Way head-on and the stars are all scattered into different orbits,” said team member Gurtina Besla of Columbia University in New York, N.Y. “The stellar populations of both galaxies are jostled, and the Milky Way loses its flattened pancake shape with most of the stars on nearly circular orbits. The galaxies’ cores merge, and the stars settle into randomized orbits to create an elliptical-shaped galaxy.”

The simulations Besla was talking about came from precise measurements by Hubble, painstakingly determining the motion of Andromeda, looking particularly at the sideways motion of M31, which until now has not been able to be done.

“This was accomplished by repeatedly observing select regions of the galaxy over a five- to seven-year period,” said Jay Anderson of STScI.

[. . .]

Of course, the collision is not like a head-on between two cars that takes place in an instant. Hubble data show that it will take an additional two billion years after the encounter for the interacting galaxies to completely merge under the tug of gravity and reshape into a single elliptical galaxy similar to the kind commonly seen in the local universe.

Astronomers said the stars inside each galaxy are so far apart that they will not collide with other stars during the encounter. However, the stars will be thrown into different orbits around the new galactic center. Simulations show that our solar system will probably be tossed much farther from the galactic core than it is today.

There’s also the complication of M31′s small companion, the Triangulum galaxy, M33. This galaxy will join in the collision and perhaps later merge with the M31/Milky Way pair. There is a small chance that M33 will hit the Milky Way first.

The astronomers working on this project said that they were able to make the precise measurements because of the upgraded cameras on Hubble, installed during the final servicing mission. This gave astronomers a long enough time baseline to make the critical measurements needed to nail down M31′s motion.

Bad Astronomy's Phil Plait did a good job outlining the mechanics of the collision.

Over the next few billion years, Andromeda — currently a barely naked-eye object in the northern sky — will grow larger as it approaches. In just under 4 billion years, the mutual gravity from the two galaxies will start to play havoc on each other. The Milky Way and Andromeda are about the same mass, so the effects they will have on each other will be profound. Stars on the outskirts of both galaxies will be drawn out, and long tails or streamers of stars and gas will be flung out.

Then, over a hundred or so million years, the galaxies will physically collide. Stars are small and so far apart on galactic scales that the odds of two stars colliding (or even getting close enough to affect each other or any planets) are actually incredibly small. But gas clouds are huge, light years across, so head-on collisions between them is inevitable. They’ll crash into each other, collapsing, and furiously form new stars. These stars will light up the gas, and from a distance the two galaxies will be seen have long strings of fiercely glowing red gas along their arms, like the Antenna galaxies, shown here.

The two galaxies will probably pass right through each other, pulling apart even as chaos reigns inside each. But the pull of gravity will not be denied. They’ll slow as they draw apart, eventually stop, and fall back in to each other. At that point they’ll merge, becoming a single, larger galaxy. It will probably be an elliptical galaxy, a big fuzzy cotton ball, as opposed to the spiral that each galaxy is now. That will take about two billion years after the initial collision, or six billion years from now.

Interestingly, the Sun will still be around then. It’ll be different, having used up most of its nuclear fuel, and on its way to becoming a red giant. But it’s possible the Earth and other planets will still exist! So it’s possible someone (maybe not resembling humans too much, but still) may yet be around to watch this event unfold.

The Sun’s orbit around the galaxy will change, though. Right now we orbit the Milky Way’s center in a roughly circular path, taking over 200 million years to complete one orbit. According to the models the astronomers developed using the Hubble observations, during the collision the Sun will be flung into a looping elliptical orbit around the new galaxy’s center, taking it farther out than we are now. That may be a good thing: both the Milky Way and Andromeda have supermassive black holes in their cores, and these black holes will merge eventually as well. It’s unclear what will happen when this occurs (though we may become an active galaxy, spewing out huge amounts of energy), but I suspect it’s best to be as far from that as possible when it does!

These new results make me pretty happy. We knew that a collision was inevitable, but the timing has always been a question. In my book Death from the Skies! I wrote a chapter on this event, but based on what was known at the time (just a few years ago!) it was supposed to happen in 1-2 billion years. These new results double that to 4 billion, which means I have a firmer number to quote. Moreover, we didn’t know if it would be a glancing blow at first or a head-on collision, and it looks now like it’s headed right at us.

Plait's YouTube account hosts a nifty animation of the collision as expected.

By this time, the Earth will be uninhabitable, the warming and expansion of our Sol helping push our homeworld into a Venus-like state. (If nothing interferes, that is.) Everyone commenting on this is right to note that the galaxy formed by this collision would be a spectacular thing to see in our night skies.