If E.T. had to rely on his family getting a radio signal from Earth to find him, he would probably still be waiting to get home. At least, that’s what a new theory on when extraterrestrials will receive signals from Earth suggests.

The assumption that most things are average, called the mediocrity principle, means we can bet that life on Earth-like planets is pretty normal. Evan Solomonides, a 19-year-old Cornell University student, took this idea and combined it with the Fermi Paradox in a new way to predict when we might hear back from aliens.

“It becomes likely we will have heard [aliens] around 1,500 years from now,” says Solomonides. “Until then, it is possible that we appear to be alone – even if we are not.”

Our general loneliness in the universe is the heart of the Fermi Paradox, which is the conundrum that there are at least a billion planets in the Milky Way that we think could have life — and yet we have been totally unable to find it.

“Even our mundane, typical spiral galaxy not exceptionally large compared to other galaxies – is vast beyond imagination,” says 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.”

We have been broadcasting TV and radio into space for about 80 years, reaching about 3,555 of the billion Earth-like planets in our galaxy. According to Solomonides’ calculations, once we have contacted about 3,000 light years of the Milky Way, it becomes likely that an alien civilization will send a message back.

“This is not to say that we must be reached by then or else we are, in fact, alone,” says Solomonides. Instead, it just becomes probable that we will hear from extraterrestrials at that point.

He says, “we haven’t heard from aliens yet, as space is a big place – but that doesn’t mean no one is out there.”