Finding life other than on Earth is a tricky, and sometimes loaded question. It can depend on whether you just mean living organisms or intelligent life. Opinions on this can also be shaped by people’s individual religious beliefs. Though, these are opinions, and what we’re really concerned about is making an educated fact-based scientific guess.
So let’s start with the basics:
Requirements for life
National Geographic has an interesting Q&A article on necessary conditions for life. In short though, you need water, oxygen, the right temperature and metabolic energy (sunlight or other). That’s not a big list. Mostly, this is about energy transfer. Keep in mind, we’re talking about any form of life here, anything from the most basic microbes on up.
There’s been a hope of finding microbial life on Mars, but recently that hope has been fading. There are other places in the solar system though, that could still harbor life, including Europa, Enceladus and Titan, all places with lots of energetic stuff going on. Personally, I look more at Europa and Enceladus because of their vast amounts of water. Europa is theorized to have more water than all of Earth’s oceans combined. And while it has a 10-mile thick solid ice crust, beneath that could be liquid water that may be warmed by geothermal activity.
There are even some theories that it might even be possible for life to exist on Venus, our super hot twin sister planet. And by hot, I mean 864 degrees Fahrenheit. But, in the upper atmosphere things become a little more hospitable. Many Venus scientists think that back a billion years ago, the planet was actually quite habitable, with oceans and a comfortable climate. It may have had more biological abundance than Earth. Over time, that changed, but some of living things may still exist as microbes in the upper atmosphere. You can read about that here: https://www.space.com/40304-venus-clouds-alien-life-search.html
Okay, this is where things get much more complicated and theoretical. For this part, we’ll use Drake’s Equation. In 1961, Dr. Frank Drake developed this equation to predict how much life may exist in the galaxy. It kind of is set up like this:
In short, if there are 250 billion stars in the galaxy (minimum estimate) there may be as many as many as 15,000 civilizations in our galaxy alone. While that seems like a lot, if they were equally spaced out, our closest neighbor could be anywhere from 2,600 to 28,000 light years away. Our current technology only allows us to detect signals up to around 500 light years. But, don’t give up hope… If you look at the galactic map, if anything stars are not evenly spaced out. Find out more about this aspect here: https://www.astrobio.net/alien-life/at-last-how-many-alien-civilizations-are-there/
So, yeah. We’re probably not that far off from finding some form of life, most likely microbial. My guess is within the next 20 years. Intelligence, however is a little farther off. Unless they come find us. But for those who believe that there is no other life, I think Carl Sagan said it best.
“The universe is a pretty big place. If it’s just us, seems like an awful waste of space.”