Maybe we are late in the universe, perhaps universe used to be a lively and vibrant place homing millions of civilizations. Now, we stand as the last remnants, hence, possibly the most advanced.
Maybe we are late in the universe, perhaps universe used to be a lively and vibrant place homing millions of civilizations. Now, we stand as the last remnants, hence, possibly the most advanced.
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If we know one thing about civilizations, it's that they leave shit around everywhere. If there once were a lot of folk about, there would still be shit for us to see today. We've looked, it seems pretty empty so far.
It would also be unlikely all of them would be dead, most sure, but not all. As far as we can see there is nothing.
We think there is almost certainly forms of life out there, stuff like single cell life. There's probably some of that in our solar system outside of Earth. More complex life would be way more rare, even multicellular would be rare. For a long time Earth was covered in sponges and it might have stopped there. And even if intelligence arises, they might not be tool users. Dolphins are pretty smart, they can't use fire or tools and won't be launching rockets any time soon. But let's say within the span of 100 million years about 10 human level civilizations would arise in our galaxy (which is probably a lot more than reality). What are the chances they get into space in a big way? Most of them would probably live in a gravity well deeper than us. That would make getting into space a lot harder. They might not have the energy budget, will or need to go into space. Their biology might be unsuited for it. But even if they do, getting to low orbit is one thing, getting beyond that is something we haven't even really done in a big way. Getting to other stars seems completely impossible with our current knowledge and no indication we are on a path to ever be able to do that. So say in the span of 100 million years there are two civilizations that live for 1 million years (we've only been around for a fraction of that). They would still most likely not only be thousands of light years apart, they would also be seperated by millions of years. And that's with some super optimistic assumptions.
So no, there is nobody out there.
There must surely be someone out there in some galaxy or solar system somewhere.
The universe is simply too big for there not to be.
It's insanely big so no matter how small the chances were for our lives to exist someone or something must also have achieved that somewhere.
There's a saying in the astronomy circles. Things happen either once, an infinite number of times, or never.
So all our evidence about life is from a sample of 1: 1 planet and it's development. Everything else is extrapolated from that. We don't know what rates of evolution should be or could be.
Also in terms of civilizations leaving junk everywhere, that is potentially true. But we also only have a sample of 1: 1 planet and 1 solar system which we have barely scratched the surface of.
The absence of evidence is not evidence in itself. We will have to go out in to the universe to see what is there.
In terms of travel to other systems - in theory self replicating ships could spread across the galaxy to every system in about 500 thousand years at sublight speed. Space travel is not doable in a humans life time, but it is doable on the scale of a stable civilizations efforts to spread into the galaxy.
There are also theoretical ways to travel faster than life. Whether they are pure fantasy or potential science only time will tell. We still can't even detect much of the universe, let alone begin to manipulate it.
We simply know too little to know what is going on in the galaxy. To say "there is nobody out there" is just a possibility, not a certainty.
There are also theoretical ways to travel faster than [light].
There are?
If you have an absolutely absurd amount of negative mass, you could create an Alcubierre warp drive that won't immediately tear your ship apart. Unfortunately there's no evidence that negative mass exists, and afaik current designs use amounts that are impossible to actually use (eg. the weight of a galaxy).
Tl;dr: Yes, but they may not be possible and may still be impractical if they were possible
Aka, The Fermi Paradox