Our galaxy is vast, but, based on the likelihood that there are billions of sun-like stars with Earth-like planets, we should have already been visited by aliens. So goes the Fermi Paradox. However, a new study suggests that alien contact could be a long way away.
A study that will be presented at the American Astronomical Society‘s meeting this month suggests that because our universe is so large we shouldn’t expect to hear from aliens for at least another thousand years.
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“It’s possible to hear any time at all, but it becomes likely we will have heard around 1,500 years from now,” said Cornell University student Evan Solomonides who will present the study. “Until then, it is possible that we appear to be alone — even if we are not. But if we stop listening or looking, we may miss the signals. So we should keep looking.”
Here’s the thinking: in order to be noticed, someone will have to hear our radio broadcast signals which have been reaching out into space for the past 80 years. These signals travel at the speed of light. But for aliens, they’re going to have to figure out what these signals are. Not only that, but they’ll also have to decipher more than 3,000 languages.
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So, Earth’s signal has reached every star within about 80 light-years. That totals up to 8.531 stars, and around 3,555 Earth-like planets (that’s using the notion that our galaxy has about 200 billion stars).
But our galaxy is incredibly vast: it is 100,000 light-years across.
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“Even our mundane, typical spiral galaxy — not exceptionally large compared to other galaxies — is vast beyond imagination,” said Solomonides. “Those numbers are what make the Fermi Paradox so counterintuitive. We have reached so many stars and planets, surely we should have reached somebody by now, and in turn been reached … this demonstrates why we appear to be alone.”
The study suggests that it will take us about 1,500 years for our signals to reach out to about half of the Milky Way.
“This is not to say that we must be reached by then or else we are, in fact, alone. We simply claim that it is somewhat unlikely that we will not hear anything before that time,” Solomonides said.