Something out there isn't playing by the rules of gravity. Harvard professor and astrophysicist Avi Loeb, one of the world's most provocative voices in cosmology, has reignited his bold theory that the interstellar object 3I/ATLAS may not be a natural visitor at all -- but a technological spacecraft under intelligent control. His latest argument centers on a new observation: the object appears to be accelerating in ways gravity alone can't explain.
At the moment of its perihelion -- the point where it came closest to the Sun -- data from NASA's Jet Propulsion Laboratory showed that 3I/ATLAS was moving with a non-gravitational acceleration. In simple words, it received an extra push from an unknown source. Two components of this motion were recorded: a radial acceleration away from the Sun and a transverse acceleration along its orbit. Though tiny by cosmic standards, according to him, these shifts are significant enough to suggest that something other than natural forces is acting on the object.
For most comets, such accelerations are caused by jets of gas and dust escaping from their icy surfaces as they warm in sunlight -- what astronomers call the "rocket effect." But Loeb argues that this explanation doesn't fit. If 3I/ATLAS were losing material rapidly enough to produce this thrust, the mass loss would be enormous -- up to a tenth of its total mass within just a few months. That kind of violent evaporation should create a massive plume visible to telescopes around the world. Yet, as Loeb notes, no such plume has been confirmed.
Even more puzzling, 3I/ATLAS has been observed to grow brighter as it moves away from the Sun, with its light curve following an unusual mathematical relationship inconsistent with natural comet behavior. Adding to the mystery, new observations show the object reflecting a bluish hue -- bluer than the Sun itself. In the natural world, dust and ice tend to scatter light toward the red end of the spectrum. For something far colder than the Sun to appear blue, Loeb suggests, it may be emitting its own light -- or being illuminated by an artificial energy source.
The combination of these anomalies -- a steady acceleration, the lack of visible mass loss, the blue coloration, and the reflective, metallic surface -- forms what Loeb calls a growing case for artificial propulsion. He proposes that the non-gravitational acceleration might be the signature of an internal engine, a controlled thrust rather than a random physical process.
ESA's JUICE spacecraft and several Earth-based observatories will soon provide new data as 3I/ATLAS approaches its closest distance to Earth in December 2025. If signs of gas emission or mass shedding appear, the natural explanation will gain strength. But if 3I/ATLAS continues to move with precise, unexplained momentum -- and keeps shining its eerie blue light -- Loeb's theory of a mothership from beyond the stars may no longer seem far-fetched.
Loeb emphasizes that science should follow the evidence, even when it challenges our basic assumptions. Just as cosmologists must face uncomfortable data about the universe's expansion, he argues, astronomers shouldn't dismiss the unsettling truth that an alien craft might already be drifting silently through our solar system.
Whether 3I/ATLAS is a natural wanderer or a visitor under intelligent command, its defiance of gravity leaves us with a haunting question: what if the universe is already knocking -- and we're refusing to hear the sound? ALSO READ|
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