Dr. Avi Loeb, the distinguished astrophysicist and chair of Harvard's Astronomy Program, just published a book called Extraterrestrial: The First Sign of Intelligent Life Beyond Earth.

In the book, Dr. Loeb calls out several specific peculiarities about the interstellar object Oumuamua. He proposes a rather shocking hypothesis:

I submit that the simplest explanation for these peculiarities is that the object was created by an intelligent civilization not of this Earth.

In interviews 1, 2, 3: Dr. Loeb mentions several peculiarities. Here are three:

  1. Oumuamua has a unique light curve. Uhoh has a nice analysis and some great graphics in this answer: Could asteroid 'Oumuamua actually be round?. Dr. Loeb claims that the high aspect ratio implies this is not a natural object. He uses an analogy of a thin piece of paper falling through the air having a less extreme aspect ratio.

  2. Oumuamua showed acceleration unaccounted for by orbital mechanics after its close pass to the Sun similar to a comet. A comet gets its push due to evaporation of gasses, but there was no evidence that Oumuamua had a tail of gas. Dr. Loeb proposes that Oumuamua may have been designed as a light sail.

  3. Dr. Loeb claims Oumuamua's velocity as it entered the Solar System is slower than 1 out of 500 near star systems in an LSR reference frame.

Does the evidence support Dr. Loeb's hypothesis that Oumuamua is most likely of extra-terrestrial origin?

  • 5
    $\begingroup$ I think you have posed this question well in a way that makes clear it is on topic. However, I am not sure we can really make a satisfactory answer to this here. Dr. Loeb's publications are still relatively new and I feel like any answer here wouldn't be better than a single paper by another scientist--and likely less reliable than that. $\endgroup$
    – called2voyage
    Jan 27, 2021 at 19:33
  • 1
    $\begingroup$ I suggest watching this video from Dr. Kippling. It explains fairly the current state of the debate. Spoiler: Avi Loeb is extremely optimistic and is making a wild statement here, even if speculatively productive youtube.com/watch?v=qX_Bj7064Ms $\endgroup$
    – Swike
    Jan 27, 2021 at 20:05
  • 2
    $\begingroup$ @called2voyage Perhaps you are correct, but I don't think we should shy away from questions that are difficult or even taboo in astronomy. Not that you were suggesting we do so, of course. $\endgroup$
    – Connor Garcia
    Jan 27, 2021 at 20:11
  • $\begingroup$ I would contend that anyone who thinks the most logical explanation for anything (in space) that isn't man-made is that it's alien-made simply doesn't understand how vastly, hugely, mindbogglingly big space is (and how complex nature is). $\endgroup$ Jan 27, 2021 at 20:17
  • 3
    $\begingroup$ Please, why the downvote? $\endgroup$
    – Connor Garcia
    Jan 28, 2021 at 5:53


You must log in to answer this question.

Browse other questions tagged .