Here’s an interesting thought. We know that at least two objects from outside our Solar System have appeared in our skies, the comet 2I/Borisov and the still enigmatic object called ‘Oumuamua. Most attention on these visitors has focused on their composition and the prospects of one day visiting such an interloper, for it is assumed that with new technologies like the Vera Rubin Observatory and its Legacy Survey of Space and Time (LSST), we will be picking up more of the same. But consider origins. Extrapolating backward to figure out where either object came from quickly exhausts the most patient researcher, for it only takes the slightest changes in trajectory to widen the search field so broadly as to be useless. That’s especially true since we don’t know the ages of the objects, which may span hundreds of millions of years. Enter Cole Gregg (University of Western Ontario), who has embarked on a project to study the question from a different perspective. Gregg asks how likely it...

Given our decades-long lack of success in finding hard evidence for an extraterrestrial civilization, it hardly comes as a surprise that a recent campaign studying the seven-planet TRAPPIST-1 system came up without a detection. 28 hours of scanning with the Allen Telescope Array by scientists at the SETI Institute and Penn State University produced about 11,000 candidate signals for further analysis, subsequently narrowed down to 2,264 of higher interest. None proved to be evidence for non-human intelligence, but the campaign is interesting in its own right. Let’s dig into it. The unique configuration of the TRAPPIST-1 planets allowed the scientists involved to use planet-planet occultations (PPOs). A cool M-dwarf star, TRAPPIST-1 brings with it the features that make such stars optimal for detecting exoplanets. The relative mass and size of the planets and star mean that if we’re looking for rocky terrestrial-class worlds, we’re more likely to find and characterize them than around...

Is it possible that we can account for the Fermi paradox by looking to our own behavior as a species? Some science fiction of the 1950s pointed in that direction, as witness The Day the Earth Stood Still (1951). Dr Kelvin F Long addresses the question in terms of the 'zoo hypothesis' in the essay below, asking what our culture could do to make itself less threatening to any outsider. Long is an aerospace engineer, astrophysicist and author. He leads the Interstellar Research Centre, a division of Stellar Engines, which conducts research on the science and technology associated with deep space exploration. He is a Chartered Member of the Institute of Physics and a Fellow of the British Interplanetary Society. He tells me he wrote this article as a means of fundamental protest at the current conflicts engulfing humanity and as a plea to any observing ETI not to judge our species by the immorality of those who hold power over the potential of humankind. Also available on his site are...

Every time I mention a Brian Aldiss novel, I have to be careful to check the original title against the one published in the US. The terrific novel Non-Stop (1958) became Starship in the States, rather reducing the suspense of decoding its strange setting. Hothouse (1962) became The Long Afternoon of Earth when abridged in the US following serialization in The Magazine of Fantasy & Science Fiction. I much prefer the poetic US title with its air of brooding fin de siècle decline as Aldiss imagines our deep, deep future. Imagine an Earth orbiting a Sun far hotter than it is today, a world where our planet is now tidally locked to that Sun, which Aldiss describes as “paralyzing half the heaven.” The planet is choked with vegetation so dense and rapidly evolving that humans are on the edge of extinction, living within a continent-spanning tree. The memory of reading all this always stays with me when I think about distant futures, which by most accounts involve an ever-hotter Sun and the...

I want to return to Mars this morning because an emerging idea on how to terraform it is in the news. The idea is to block infrared radiation from escaping into space by releasing engineered dust particles about half as long as the wavelength of this radiation, which is centered around wavelengths of 22 and 10 μm, into the atmosphere. Block those escape routes and the possibility of warming Mars in a far more efficient way than has previously been suggested emerges. The paper on this work even suggests a SETI implication (!), but more about that in a moment. Grad student Samaneh Ansari (Northwestern University) is lead author of the paper, working with among others Ramses Ramirez (University of Central Florida), whose investigations into planetary habitability and the nature of the habitable zone have appeared frequently in these pages (see, for example, Revising the Classical ‘Habitable Zone’). The engineered ‘nanorods’ at the heart of the concept could raise the surface temperature...

Mars was a lively destination in early science fiction because of its proximity. When H. G. Wells needed a danger from outer space, The War of the Worlds naturally looked toward Mars, as a place close to Earth and one with the ability to provoke curiosity. Closely studied at opposition in 1877, Mars provoked in Giovanni Schiaparelli the prospect of a network of canals, surely feeding a civilization that might still be alive. No wonder new technologies turned toward the Red Planet as they became available to move beyond visible light and even attempt to make contact with its inhabitants. All this comes to mind this morning because of an intriguing story sent along by my friend Al Jackson, whose work on interstellar propulsion is well known in these pages, as is his deep involvement with the Apollo program. Al had never heard of the incident described in the story. It occurred in 1924, when at another Martian opposition (an orbital alignment bringing Earth and Mars as close as they’ll...

Until we learn whether or not life exists on other planets, we extrapolate on the basis of our single living world. Just how long it took life to develop is a vital question, with implications that extend to other planetary systems. In today's essay, Alex Tolley brings his formidable background in the biological sciences to bear on the matter of Earth's first living things, which may well have emerged far earlier than was once thought. In particular, what was the last universal common ancestor -- LUCA -- from which bacteria, archaea, and eukarya subsequently diverged? Without the evidence future landers and space telescopes will give us, we remain ignorant of so fundamental a question as whether life itself -- not to mention intelligence -- is a rarity in the cosmos. But we're piecing together a framework that reveals Earth's surprising ability to spring into early life. by Alex Tolley Once upon a time, the history of life on Earth seemed so much simpler. Darwin had shown how natural...

A favorite editor of mine long ago told me never to begin an article with a question, but do I ever listen to her? Sometimes. Today’s lead question, then, is this: Can we expand communications over interstellar distances to include quantum methods? A 2020 paper by Arjun Berera (University of Edinburgh) makes the case for quantum coherence over distances that have only recently been suggested for communications: …We have been able to deduce that quantum teleportation and more generally quantum coherence can be sustained in space out to vast interstellar distances within the Galaxy. The main sources of decoherence in the Earth based experiments, atmospheric turbulence and other environmental effects like fog, rain, smoke, are not present in space. This leaves only the elementary particle interactions between the transmitted photons and particles present in the interstellar medium. Quantum coherence is an important matter; it refers to the integrity of the quantum state involved, and is...

When Arthur C. Clarke tells me that something is terrifying, he’s got my attention. After all, since boyhood I’ve not only had my imagination greatly expanded by Clarke’s work but have learned a great deal about scientific methodology and detachment. So where does terror fit in? Clarke is said to have used the term in a famous quote: “Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.” But let’s ponder this: Would we prefer to live in a universe with other intelligent beings, or one in which we are alone? Are they really equally terrifying? Curiosity favors the former, as does innate human sociability. But the actual situation may be far more stark, which is why David Kipping deploys the Clarke quote in a new paper probing the probabilities. Working with the University of Sydney’s Geraint Lewis, Kipping (Columbia University) has applied a thought experiment first conceived by Edwin Jaynes to dig into the matter. Jaynes (1922-1998)...