That's true. But there's a separate question, why no radio frequency evidence of other stars. I want to see some estimates of the liklihood of radio freq of some kind of communication in just our galaxy. How many stars might have earth-distanced planets from a sun - 6 billion in just our galaxy! Details below from a paper.
If there were this many, I hope in my lifetime we hear from some, just evidence of other intelligent life.
Here's a paper that estimates the presence of these planets from the Kepler space observatory.
https://www.icds.psu.edu/how-many-earth-like-planets-are-aro...
From 2019, it says using data from Kepler, they estimate that a close to earth sized planet (3/4 to 1.5 size of the earth) was in an orbit that could potentially have water vapor from a sun, orbital periods 327 to 500 days, with fairly large error bars:
* somewhere in the range of 1 of every 33 stars to as high as one such planet for every 1 out of 2 stars in our galaxy.
That's a large range, but given we have at least 200 billion stars in just our own Galaxy, that lower bound is about 6 billion stars with somewhat close to earth-distance planets, in just our galaxy. If this is over estimating by a million times, that's still 6 million planets in the earth like orbiting range. So let's make some noise, aliens.
This source says estimates are 200 to 400 billion stars in the milky way. https://bigthink.com/starts-with-a-bang/how-many-stars-milky...
If there were this many, I hope in my lifetime we hear from some, just evidence of other intelligent life.
Here's a paper that estimates the presence of these planets from the Kepler space observatory. https://www.icds.psu.edu/how-many-earth-like-planets-are-aro...
From 2019, it says using data from Kepler, they estimate that a close to earth sized planet (3/4 to 1.5 size of the earth) was in an orbit that could potentially have water vapor from a sun, orbital periods 327 to 500 days, with fairly large error bars:
* somewhere in the range of 1 of every 33 stars to as high as one such planet for every 1 out of 2 stars in our galaxy.
That's a large range, but given we have at least 200 billion stars in just our own Galaxy, that lower bound is about 6 billion stars with somewhat close to earth-distance planets, in just our galaxy. If this is over estimating by a million times, that's still 6 million planets in the earth like orbiting range. So let's make some noise, aliens.
This source says estimates are 200 to 400 billion stars in the milky way. https://bigthink.com/starts-with-a-bang/how-many-stars-milky...