With enough space and time, anything is possible. Even aliens.
Approx. 700 words; 3 minutes read time
The universe is big. It's so big that extraterrestrial life seems possible. But like two ships passing in the night, how will we ever meet up with an alien in all that space? The thing is, the universe is not only big, but it's also old. Both the size and age of the universe increase our odds that alien life is out there…and will contact us.
We know the universe is big. But we also know how big because we can measure it. We use "standard candles" - space signposts - to calculate interstellar distances. Standard candles include pulsating stars, their relative positions, and changes in light wavelengths. These allow us to infer distances between Earth and other star systems. As for the size of the universe: it's 93 billion light-years across. One light-year is 5.88 trillion miles, so the universe is 546.8 sextillion miles wide. That's a lot of space for aliens to happen.
Here are some other astronomical figures that give me hope:
- There are 2 trillion galaxies or more in the visible universe, each with billions of stars.
- Most if not all stars have planets. Many of these are Earth-like, being the right distance from their star to be habitable.
- The Milky Way, our home galaxy, contains 400 billion stars. As many as 40 billion Earth-like planets could exist here.
One major caveat: all these planets outside our solar system are super far from Earth. Even the closest star, Proxima Centauri, is 4.2 light-years away. That's 24.7 trillion miles. And most stars are much further away than that. Even if intelligent life exists elsewhere in our universe, we could not visit it. At least not yet.
Here is where we factor in time.
Yes, it would take a long time to travel interstellar distances. But that's given our current limited ability and knowledge. Odds are civilizations far more advanced than ours have figured out how to do it faster.
The universe is about 13 billion years old. Earth is only 4.5 billion and is young by comparison. Many habitable planets are much older, even billions of years more than Earth. That's a crazy amount of time for advanced civilizations to evolve. These aliens, if they exist, have a head-start on us by millions or even billions of years. Conceivably they have overcome the significant limits of space by now. They've gone interstellar.
Even if they haven't ventured out towards us, their signals likely have. First contact may in fact be radio communication, not an in-person visit. Radio like all electromagnetic radiation travels at the speed of light. It's the fastest means we know to communicate.
Given the universe's age, countless civilizations could have broadcasted at some point. That's the bet we're making with SETI – the search for extraterrestrial intelligence. We've set up vast arrays of radio antennas in the hopes of intercepting a transmission. No luck yet. But I like many, remain hopeful.
There are those among us who don't believe. These nonbelievers postulate we haven't heard anything because there isn't anyone out there. That's a sad thought to me. Sadder still is the idea civilizations collapse shortly after they begin transmitting radio. And long before they become interstellar.
I find these hypotheses too bleak to accept. While that's not scientific, neither is taking no proof as disproof. Instead, I prefer to keep waiting for that call or visit from space.
I'm not alone in hoping for aliens. Many scientists, artists, writers, and filmmakers share this lifelong dream. Hope keeps us all imagining, studying and searching. And if hope keeps us going, then the numbers give us reason to believe.
There's a whole lot of space out there and a whole lot of time. Given enough of each, amazing things can happen.
Until next time. Science. Fiction. Create.
JRC