TL;DR - It's not a paradox, because we're probably alone. Kind of a letdown!
There was recent news from NASA about the discovery of organic molecules on Mars and the possibility of life there at some point in the past. Discovery that life once existed on Mars would blow up the assumptions in the Drake equation.
As for the Fermi paradox I'm still of the opinion that its solution is simple but depressing: Interstellar travel is so difficult that by the time you're capable of it you don't need it anymore, and even when you're capable of it you still don't get very far outside of your stellar neighborhood. Unlimited power systems, reactionless drives, and FTL travel (or even high-c travel) are depressingly impossible. And then the cold hand of entropy and the aggregate chance of disaster make it extremely dangerous to even attempt. Basically without Sci-Fi propulsion/power you end up traveling at an interstellar snail's pace, and the longer the trip the more likely it is that a random meteorite smashes through your vessel, or you simply run out of spare parts and materials to make them, and the amount of fuel you need to just keep the lights on becomes enormous.
If you can build a starship that can travel between solar systems with our current understanding of physics, then you can build orbital colonies for basically unlimited living space much much easier. For one, they can be powered by solar cells instead of needing to carry fuel. It's not like we are going to run out of raw materials either. Even restricting yourself to the belt the amount of material available would last basically indefinitely. Worst case you can start breaking up moons.
So even in a universe full of life everybody is alone. Especially if you think about how genetic algorithms tend to get hung up on local maxima, so lots of planets waste millions of years with dumb dinosaurs with no space program or radio telescopes.
> There was recent news from NASA about the discovery of organic molecules on Mars and the possibility of life there at some point in the past.
It should be pointed out that the organic molecules in question are known to be created by abiotic processes.
> As for the Fermi paradox I'm still of the opinion that its solution is simple but depressing: Interstellar travel is so difficult that by the time you're capable of it you don't need it anymore, and even when you're capable of it you still don't get very far outside of your stellar neighborhood.
Well, there's an even more depressing possibility: interstellar communication itself is effectively impossible, let alone travel. Any beam will spread out over a larger and larger radius, so even the most focused laser beams will become too weak to detect within I think a few hundred light years, so we're not even talking about trying to find aliens in the galaxy, we're talking about trying to find aliens in the nearest stars.
Plus, even at lightspeed you're talking multi-year roundtrips to our nearest interstellar neighbors.
Our entire history of radio emissions has only made it to around 500 solar systems currently. Even if someone was listening and responded immediately the response probably wouldn't have made it back to Earth yet.
That's something I think people ignore. It takes 4 years to get to the next closest star at the fastest possible speed.
And that's ignoring all of the other issues with long term space travel. 4 years. To a place where we're relatively certain doesn't have life capable of technology.
The assumption that other intelligent life will conveniently find a way around the speed of light is a big one.
"Theoretically, time dilation would make it possible for passengers in a fast-moving vehicle to advance further into the future in a short period of their own time. For sufficiently high speeds, the effect is dramatic.[2] For example, one year of travel might correspond to ten years on Earth. Indeed, a constant 1 g acceleration would permit humans to travel through the entire known Universe in one human lifetime.[12] Space travelers could then return to Earth billions of years in the future. A scenario based on this idea was presented in the novel Planet of the Apes by Pierre Boulle, and the Orion Project has been an attempt toward this idea."
https://en.wikipedia.org/wiki/Time_dilation#Velocity_time_di...
1. An infinite power source
2. A reactionless drive
3. A spacecraft made of material so strong that it can survive collisions with rocky material at velocities very close to c. Or a Star Trek style deflector shield.
Warp drive is probably easier to achieve.
Detonating nukes behind your spaceship will never give you anything close to 1G constant acceleration over a long period of time.
Time dilation has some definite drawbacks as well. Say for example you have a very redundant ship that can repair damage from micrometeorite attacks in a few minutes. The hits are very rare, maybe once a year at most at normal velocity. But now you're traveling at a high fraction of C and you're hitting tens of fragments per second, and always at a high fraction of C. Your repair process is effectively working in slow motion and could very easily get overwhelmed. Without a sci-fi energy shield your spacecraft is ablated to death long before you get anywhere.
At lightspeed it's an instantaneous trip to the traveler. It's only a multi-year trip to those who are still on Earth.
(And the weird thing about that is that I feel it's a bad thing for some reason, but I can't articulate a coherent argument against it.)
Whether it's colonizing other planets or making a full-dive VR; just thinking about the time when we can do any of these things gives me a headache.
> we find a substantial probability that we are alone in our galaxy, and perhaps even in our observable universe (53%–99.6% and 39%–85% respectively).
> ’Where are they?’ — probably extremely far away, and quite possibly beyond the cosmological horizon and forever unreachable.
[1] https://www.heartland.org/publications-resources/publication...
... in the observable universe.