For the Love of Evidence

Avi Loeb
6 min readOct 30, 2022
An artist illustration of quantum entanglement for a pair of particles with opposite spins (Credit: NSF)

An “imagined reality” is an addictive mental drug that humans are infatuated with. It cures the frustration brought about by the constraints of the actual reality. Like a physical drug, it could cure pain and make life in prison more tolerable, but it could also take away life if used excessively. It brings communities with a shared spiritual belief together but it can also lead to terrorism and hatred.

An imagined reality satisfies an emotional need. If the need is to demonstrate mathematical virtuosity with minimal constraints from the physical world, then the imagined reality could involve extra dimensions or the multiverse. If the need is to be liked on Twitter, then the imagined reality will echo a popular community.

The scientific method pioneered by Galileo Galilei calls for an independent arbitrator regarding the procedure by which we figure out the world, namely experimental data from instruments, independent of humans. Such data often limits the range of possibilities and rules out beautiful ideas that are not realized in nature. Nature is one version of reality among the many possible ones.

Truth and beauty are not necessarily the same. There are more beautiful realities than the true one. Finding it requires submission to experimental evidence and giving up on wishful thinking. Laying the head of wishful thinking under the guillotine of data is stubbornly difficult for most people, irrespective of whether they are engaged in politics, spirituality or the practice of science.

The most striking examples in science are those where evidence indicated that the prevailing paradigm is an imagined reality. Such was the notion that the Sun is made of the same material as the Earth, until Cecilia Payne-Gaposchkin realized that it is made mostly of hydrogen, but Henry Norris Russell dissuaded her from including this statement in her PhD thesis. Such was the notion that the Universe is made of the same matter as the Sun, until Fritz Zwicky realized that the dominant constituent is dark matter and his discovery was ignored for forty years by mainstream astronomers. Such was the mainstream notion of causality in classical physics, when quantum mechanical entanglement was discovered, and Albert Einstein resisted it as “spooky action at a distance”. Such may be the mainstream notion that interstellar objects are natural rocks of a type that we had never seen before, like hydrogen or nitrogen icebergs. Once the Galileo Project will find the composition of the first interstellar meteor or get a high-resolution image of the next `Oumuamua-like object, we will know whether social pressure to stay within the box was because the box was misplaced.

The key for advancing our scientific knowledge is to use preliminary intriguing evidence as a motivation for collecting more data, rather than promoting imagined realities that we had never seen before as an argument that collecting new data is a waste of time.

In that vein, Henry Norris Russell collected new data for four years after being intrigued by Cecilia’s thesis, and then published a paper confirming her finding. Similarly, Vera Rubin collected new data on galaxies and confirmed Zwicki’s claim of invisible matter forty years later. Also, the Nobel Prize in Physics was awarded this year to Alain Aspect, John Clauser and Anton Zeilinger, who demonstrated experimentally the reality of quantum entanglement. In this spirit, the research team of the Galileo Project is engaged in collecting new data; this week the Project’s suite of instruments will start a continuous video and audio filming of the sky, and within the coming year — Project scientists will conduct an expedition to retrieve the fragments of the first interstellar meteor near Papua New Guinea.

Imagined realities can consume the oxygen in the room. Galileo was put in house arrest when the imagined reality of a geocentric world flattered the egos of the dominant forces in society. The lesson is not to promote hypothetical entities, like extra dimensions or wormholes, as the centerpiece of the mainstream of theoretical physics for half a century without a shred of experimental test for their existence. The best way to maintain a sanity balance is to adhere to experimental tests as our guide, first and foremost in physics. Physics is a learning experience, a dialogue with nature rather than a monologue. Our love of nature is not abstract or platonic, but based on a direct physical interaction with it.

Nature is under no obligation to satisfy our emotional needs. Feeling lonely does not imply that we have neighbors. But we can check if we have neighbors by looking through our windows rather than repeating endlessly Enrico Fermi’s question: “where is everybody?”. Nature is also under no obligation to satisfy our intellectual needs. Figuring out the most consequential insight about nature — whether we are alone as a sentient species among the stars, may not require sophisticated mathematical gymnastics. It only requires looking up.

The culprit is our ego. It leads us to ignore facts that do not flatter us. We would rather be at the center of the Universe as the main actors of the cosmic play. But the reality is that the Earth moves around the Sun, which moves around the center of the Milky Way, which recedes away from all other galaxies at an accelerated rate. We arrived on stage at the end of the cosmic play and we better seek other actors who can tell us what this play is about.

We often dismiss unflattering evidence by ridiculing the messengers. However, not reading the morning news does not make the news go away.

The quest for scientific knowledge should not be focused on us. It is about figuring out the reality around us. Our starting point should be humility, driven by intellectual curiosity and informed by what we already learned. We follow this path as kids but something goes wrong when we become adults and pretend to know more than we actually know. There was no bigger expert on stars than Henry Norris Russell at his time. There was no bigger authority on modern physics than Albert Einstein at his time. But both were completely wrong about a fundamental aspect of their craft. Both promoted imagined realities that their mainstream communities supported. To learn something new, we must preserve the sense of wonder that we all started with as kids and not dissuade PhD students from including surprising results in their PhD thesis.

Just as in a relationship of true love, we must focus on the other and adapt to it rather than imagine what we want the other to be and ignore the evidence that disagrees with our preconceived notion. Adaptation to evidence often leads to a better relationship with reality.

Climate change will occur if we do nothing to fix it, irrespective of our narrative. The Sun will boil off all the oceans on Earth even if we all wear goggles which display an imagined reality in which we live comfortably in the metaverse.

Accepting the arbitration of experimental data is a survival mechanism. Natural selection favors those who adapt to the real world. The dinosaurs of the world disappear because they are not humble enough to search the blue skies for new evidence about the existential risks they face.


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 June 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".