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I’ve done everything I can think of to improve my mindfulness. I’ve tried countless meditation apps and breathing exercises to stay in the present, and I’m always working on improving my mental health. 

What helps me stay grounded has nothing to do with any of that. It’s an app for identifying birds. 

Cornell Lab of Ornithology’s Merlin Bird ID launched in 2014 to help people identify the birds they see and hear. Thanks to eBird, the world’s largest database of bird sounds and photos based on 800 million global sightings, the app allows you to record a bird, answer a series of questions or upload a photo to name your winged friend. Or you can simply use the app to explore the different birds in your area, no matter where you are in the world, and even if you’re offline. 

One of my favorite features of Merlin Bird ID is that you can use it to keep track of your bird sightings and, like an IRL Pokemon GO, “collect ’em all.”

The first time I used the app, I sat out on my balcony, clicked the green “Sound” button and watched as the app identified the birds chirping and singing in all directions. You can see the different sound frequencies as they appear on a real-time spectrogram, a visual representation of the audio world. The next time I checked the clock, I was shocked to see that an hour had passed. Then, I dug out my binoculars and let even more time fly.

As any Merlin Bird IDer knows, there is no thrill quite like pressing the “This is my bird” button for the first time, and it never gets old. From there, you can record your location. The app, in turn, will save your report to improve its performance. 

Before long, I had different bird sounds memorized. In the morning, I would wake to the sound of a California Towhee’s alarm-like and frankly, yes, annoying cheeping from a tree outside my window right as the sun started to rise. On walks around my neighborhood, I’d auditorially part the sound of cars and distant construction to hear the melody of House Finches mixed with staccato chirps of Lesser Goldfinches and the droning coos from a pair of Mourning Doves religiously stationed on electrical wires. It was the song that had been the soundtrack of my world, but I hadn’t noticed until now. 

By sight, I’d recognize Red-Whiskered Bulbuls with their black crests and fire engine cheeks, a blush color waiting to be replicated in powder form. Black Phoebes made themselves known with their fluffy soot-black heads, statue stillness and ivory bellies. At the hummingbird feeder on my balcony, there is a never-ending line of customers with iridescent throats in sunset colors: Anna’s Hummingbirds (my favorite, as you might guess), Allen’s and even the uncommon Rufous, who spend all day fighting over sugar water when not watching the feeder from their magnolia tree perches. 

What’s most thrilling is when the Merlin Bird app hears a bird that you can’t see, making it feel as though it’s your mission to treasure hunt your way to it. This is often a lesson in patience, as it may take you several tries to find the songbird you seek. Recently, while sitting in a new-to-me park, the app told me a Mountain Chickadee was nearby and I spent the next 45 minutes trying to spot it with my binoculars. It ended up on a branch directly above my head, and when I got up to leave, it flew down right by my face as if in on the joke that it was there the whole time. 

I’ve yet to find the Red-Winged Blackbird who always seems to be just out of reach, no matter where I am in my city, but I console myself with the seemingly all-knowing flock of Common Ravens (also unjustly called an “unkindness”) evermore on my street and the surprising number of noises they can produce. 

I also often listen back to the comforting hoo-hoos of a Great Horned Owl singing a 9:30 p.m. lullaby right before the start of spring. I like time-travelling to these moments, though I have come across some retrospectively hilarious conversations I unintentionally recorded in between birdsong. With that being said, Merlin Bird ID does save your audio recordings but only on your device in the app. To share the recordings with eBird, you have to manually export and upload them. 

I now seek out unexplored wooded spaces to meet new feathered friends, an excuse for forest bathing, which has led me to see the shade of blue unique to a Ruddy Duck’s bill. After a rainstorm, I’ve come across a group of Acorn Woodpeckers with impressive red mohawks excitedly pecking wet, softened wood while calling to each other. Like a conversation between punk besties over dinner. My area is known for its large flocks of Amazon parrots (and their persistent screeches), whom I’ve now had the pleasure of seeing up close as they use their light yellow bills to climb trees and collect their berries. And once, just once, I caught the backside of a Yellow Warbler in a nearby watershed park. 

Because of this app, I’ve spent more time listening to the world around me and less time in my own head, bobbing between the past and future. I’ve found myself surrounded by and in conversation with nature more than ever before. It may be the closest thing we have to magic here on Earth. Now, perhaps that is the key to grounding yourself: Getting your butt on the ground and taking the time to listen to those who are singing around you. 

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A simple way to distinguish a spacecraft from a rock is through its large non-gravitational acceleration. A natural icy rock like a comet is propelled by its mass loss. That mass loss can be observed through the cometary plume of gas and dust that surrounds the comet’s nucleus. By measuring the rate of mass loss and the characteristic ejection speed of gas and dust, one can calculate the rate of momentum change per unit time, or the non-gravitational force exerted on the nucleus. Since the evaporation occurs on the dayside of the rock which is warmed up by the virtue of it facing the Sun, this force pushes the comet’s nucleus away from the Sun. At a large enough distance, typically a few times the Earth-Sun separation, the surface of the nucleus is not warmed enough by sunlight to release volatile ices and dust and the cometary activity diminishes.

A technological object, on the other hand, could operate an engine and maneuver independently of the Sun. It can be propelled towards the Sun or any planet of interest and exhibit a non-gravitational acceleration of arbitrary magnitude or direction. Observing non-gravitational maneuvers could shift the ranking of an interstellar object on the “Loeb scale”, from `0’ — the default value for a natural comet to `10’ — a definitely artificial object.

Given this perspective, it is of great interest to measure the acceleration of the new interstellar object 3I/ATLAS along its path through the Solar System and check whether it shows any deviation from the expected trajectory, as dictated by gravity alone. If 3I/ATLAS will not continue along its expected path after its closest approach to the Sun on October 29, 2025, then the stock market might crash from worries about an alien tech visitation.

If 3I/ATLAS is a natural comet, what is its expected non-gravitational acceleration?

The recent imaging of 3I/ATLAS by the Hubble Space Telescope shows a glow ahead of the object but no bright tail of gas and dust behind it — as often observed for comets (see related paper here). In addition, spectroscopic measurements show no evidence for molecular or atomic gas accompanying this glow (see related papers here, here and here, as well as the discussion about water ice here). A natural interpretation of these anomalies is that 3I/ATLAS is a dust-rich comet that releases little gas, but mostly large dust particles which are not pushed back by Solar radiation pressure or the Solar wind because of their small surface-to-mass ratio. In this case, we can calculate the expected non-gravitational acceleration of this comet from the observed plume of dust leading it.

A detailed analysis of the observed glow ahead of 3I/ATLAS (see related paper here) suggests a mass loss rate of up to 60 kilograms per second for dust particles of 100 micron size (where a micron is a millionth of a meter) and an ejection speed of ~2 meters per second in the direction of the Sun. The estimated mass loss rate drops to 6 kilograms per second and an ejection speed of 20 meters per second for 1-micron particles. Since the non-gravitational force exerted on 3I/ATLAS equals the mass loss rate times the ejection speed, its value is the same in both cases and does not depend on the assumed size of the ejected dust particles.

The brightness distribution in the glow preceding 3I/ATLAS was also used to set limits on the diameter of its nucleus, inferred to be in the range of 0.32–5.6 kilometers. This implies that the nucleus mass is in the range of 30 billion to 200 trillion kilograms. Applying the resulting non-gravitational force to this mass leads to a non-gravitational acceleration in the range of 3×10^{-14} to 2×10^{-10} AU per day squared, where AU stands for Astronomical Unit which is defined as the Earth-Sun separation. This non-gravitational acceleration range is equivalent to values between 6×10^{-11} and 4×10^{-7} centimeters per second squared, in the direction away from the Sun.

For comparison, the first interstellar object 1I/`Oumuamua exhibited on October 25, 2017 a non-gravitational acceleration of 1.4×10^{-7} AU per day squared, equivalent to 2.7×10^{-4} centimeters per second squared (see related data here). This is larger than the expected non-gravitational acceleration of 3I/ATLAS by a huge factor, ranging between a thousand and 10 million. If 1I/`Oumuamua was a familiar comet, it had to lose about a tenth of its mass during its passage close to the Sun. But despite its large non-gravitational acceleration, 1I/`Oumuamua did not display any cometary evaporation (see observational data here), making its large non-gravitational acceleration a major anomaly concerning its nature (as argued in my related paper here).

If 3I/ATLAS is a natural comet, its outgassing may intensify as it gets closer to the Sun. A measurement of the expected non-gravitational from its cometary activity would confirm its natural origin. A paper that I wrote with my student, Sriram Elango, before the discovery of 3I/ATLAS, showed that localization data from the Webb telescope in combination with terrestrial telescopes can pinpoint the trajectory of an interstellar object to unprecedented precision using parallax, since the Webb telescope is located 1.5 million kilometers away from Earth at the L2 Lagrange point. A major deviation of the measured non-gravitational acceleration from the expected range for a comet, would suggest that 3I/ATLAS might be propelled technologically.

For now, we cannot assess with any confidence whether 3I/ATLAS is a natural dust-rich comet with no gaseous tail on an extremely rare trajectory, or perhaps a technological object on a path that was designed to align with the ecliptic plane of the planets around the Sun. All we know is that 3I/ATLAS exhibits a rare (0.2% probability) alignment of its retrograde path with the ecliptic plane to within 5 degrees, and its arrival time along this path is perfectly suited for a close encounter with Mars, Venus and Jupiter (with a 0.0005% probability, as discussed here). These coincidences would allow a mothership to release mini-probes that will reach planets as they move into the mini-probes’ orbits, taking advantage of the mothership’s retrograde motion. Since 3I/ATLAS will hide behind the Sun at its perihelion on October 29, 2025, we will not be able to observe whether it releases any mini-probes into Earth’s orbit.

Exquisite measurements of the non-gravitational acceleration of 3I/ATLAS would provide an important clue about its nature. The verdict will not be decided by debates on social media, but rather by accurate measurements of instruments. This is the same as the video assisted referee (VAR) protocol used by FIFA to decide whether a goal was scored under controversial circumstances. FIFA rules by viewing data recorded by cameras, rather than by asking soccer players or the goalkeeper for their opinions. We all know that the Earth moved around the Sun for 4.54 billion years before the Vatican placed Galileo Galilei in house arrest for suggesting that. Whether 3I/ATLAS is natural or technological in origin has nothing to do with popular opinions on Earth.

ABOUT THE AUTHOR

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Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s — Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011–2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos”, both published in 2021. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.