The Great Silence
Nov 30, 2018

For the past half-century, humanity has been listening for alien radio transmissions, but so far we appear to be the only ones broadcasting into the void. Astrobiologists now seek to narrow down the search by looking for other technological and biological signatures. In this video, I explore some of the methods by which they hope to do so, and why the great silence of the universe is such a mystery.

Correction of 02:49 to 03:03

While reference #7 below does indeed suggest an instrument the size of the Square Kilometer Array could detect our radio leakage from a distance of "several hundred lightyears", it would require a full month of uninterrupted observation. This is unrealistic because our radio leakage isn't constant but rather fluctuates with the Earth's rotation. According to this paper, a more reasonable range estimate is approximately 50 lightyears.

Correction of 04:07 to 04:15

The 2012 reply to the Wow! Signal was not beamed "in the general direction whence it came" as I state during this part of the video. It was counterintuitively beamed in the opposite direction because the region from which the Wow! Signal originated was out of reach of the stationary Arecibo Telescope used to transmit the response.

Clarification of 12:23 to 12:32

During this part of the video, I state that "as of the making of this video, [Voyager 1] is the only probe to have reached interstellar space." This is technically not true. When this video was published on November 30, 2018, both Voyager 1 and Voyager 2 had entered interstellar space. Voyager 1 did so back in 2012, and Voyager 2 on November 5, 2018. However, the date of Voyager 2's crossing was not publicly disclosed until December 10, 2018. So, when this video was published, Voyager 1 was still the only probe known to have entered interstellar space.

Correction of 13:03 to 13:11

During this part of the video, I state that "modern methods of propulsion" can attain 10% the speed of light. While some proposed methods of propulsion could theoretically accelerate a spacecraft to such a speed (i.e. laser or nuclear pulse propulsion), the phrase "modern methods of propulsion" makes it sound like it's already been achieved even though it's merely theoretical.

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