The Most Exciting Signals Start in the Noise

Avi Loeb
5 min readJan 8


We wake up every morning into a reality full of familiar things and we shuffle our attention between them by ignoring the background noise. In this spirit, scientists often conduct experiments by focusing on expected results, regarding everything else as background. But sometimes the noise contains information far more significant than the anticipated signal.

For example, a percent of the white noise on old TV sets connected to a rooftop antenna originates from the Big Bang. The temperature of the cosmic radiation background is 2.73 degrees Kelvin above absolute zero, about a percent of the surface temperature on a habitable planet like Earth. And if the TV-antenna system was transported to the outskirts of the Solar system where solar heating is weaker, then a more substantial portion of the white noise would have been constituted by the cosmic signal. Interstellar travelers might use this cosmic signal for navigation rather than treat it as white noise.

Are we missing new knowledge because we insist too often on what we aim to find and ignore the rest as noise? For example, mainstream cosmologists aim to measure the parameters of the Universe to a percent level of precision. This task resembles the predictable art of “paint by numbers”. In the process of doing so, observers reduce huge data sets to a small number of measurements. I often wonder what they might have missed by reducing the vast survey data along the lines of their focused research agenda. Defining in advance what you might find makes the scientific endeavor efficient, but it also avoids opportunities to discover the unexpected.

For the beginner’s mind of young children, nothing is familiar and everything is worth attention. Therefore, when presented with a cell phone, the children of cave dwellers will not disregard the cell phone as unworthy of attention. In the process of exploring its unique features, they will press buttons and learn how to use it. Their parents, however, might argue that the cell phone is a useless rock of a type they had never seen before and move on to focus on their routine tasks. This realization gives me hope that when presented with anomalous interstellar objects, my young collaborators might entertain the notion that some of them are artificial in origin. Here, I define youth as the willingness to learn something new from the unexpected.

Starting from a blank canvas allows a fresh perspective in the art of painting reality not “by numbers”. The blanks also include lost parts that were already painted before. For these, the technological background — otherwise regarded as unrelated noise — could fill in to compensate for our losses. For example, my parents passed away a few years ago. I would have loved to maintain my conversations with them by interacting with an artificial intelligence (AI) system that was trained on their experiences and guiding principles.

A beginner’s mind allows us to consider simultaneously contrasting realities, as different as black and white. For example, one of the perks of living in New England is that the environment is covered with beautiful white fluff after snow storms. What would constitute a contrasting experience? Living near a volcano that covers the environment with a thick layer of black soot.

The duality of black and white can also be extended to astrophysics. Black holes are known to exist based on gravitational waves and direct imaging data. But Einstein’s equations are time symmetric, raising the question: Do white holes exist?

White holes would be regions of spacetime out of which matter and energy are emanating, the time reversal of the accretion process that makes black holes. We know of quasars and gamma-ray-bursts out of which energy is flowing as a result of accretion of matter towards black holes. These bright sources are fueled at the centers of galaxies or collapsing stars.

So far, astronomers did not identify white holes, but we should stay agnostic on whether such entities might exist. For example, if the Big Bang was preceded by a contracting phase that bounced, then the collapse of matter to a black hole could also end up in a bounce leading to the time-reversed solution of a white hole. This would be a consequence of quantum gravity, not forecasted by Einstein’s theory of General Relativity. Not observing white holes can be used to constrain the possibility that the observed cosmic expansion resulted from a bounce of a contracting phase. Otherwise, white holes would have been the inevitable follow-ups to the bounce from the process that makes black holes!

Recognition of the value of what we might otherwise regard as noise, also has societal importance. The biggest risk that our civilization faces is the polarization bubbles promoted by the clickbait algorithms of social media. The algorithmic amplification of the signal we wish to hear relative to the background we wish to avoid, threatens the open-minded academic discourse that cultivates dialogues rooted in difference of opinions. The threat was recognized in public announcements on free expression issued by MIT and the University of Chicago. The remedy to this societal risk is to promote the rich variety of perspectives on reality, embrace the unfamiliar, and recognize that some of what we regard as noise includes valuable signals.

Encouraging diversity of opinions implies treating the signal and noise with equal attention. The most important signals of tomorrow are part of our noise today. We better not ridicule those who dare to interpret intriguing components of the noise, or else we are doomed to remain ignorant.


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 chairs the advisory board for the Breakthrough Starshot project, and 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. His new book, titled “Interstellar”, is scheduled for publication in August 2023.



Avi Loeb

Avi Loeb is the Baird Professor of Science and Institute director at Harvard University and the bestselling author of “Extraterrestrial” and "Interstellar".