The issue is that the universe is extremely old compared to how long it took for earth to develop life. It's ample time for civilizations to develop technologies extremely far more advanced than ours. So why isn't there a single civilization that's so advanced that it builds these things?
So there must be some "filter" that prevents civilizations from doing that, whether they are alive or dead. Maybe they just don't want to, but then ALL of them have to not want to do it, which would be weird.
If we detect life close to us, it makes it more likely that there is tons of life around the galaxy, which makes it more likely that the filter is ahead of us. If we detect no life close to us, it makes it more likely that the filter is past us.
See this Kurzgesagt video about the topic: https://www.youtube.com/watch?v=UjtOGPJ0URM
I don't know how you square a utterly stupid idea like exponential population growth with the word advanced in advanced civilization. Instead this sounds like blinkered mid twentieth century thinking. Or the old science fiction trope of seeing the future as like the present but more of it.
Isn't is the other way around? I though that the main argument for the filter ahead of us is that we haven't found any civilization, which means civilizations cannot develop past some level at which they can be detected by us. But if we'll have found one, this means that such level of civilization can be passed, and therefore reduces the chances that there is a filter.
It's not my domain, but there are apparently some markers of genetic complexity that give some weight to this theory: https://arxiv.org/ftp/arxiv/papers/1304/1304.3381.pdf
This explanation does not work, because of the timescales.
Five thousand years ago, we built the Pyramids. Fifty years ago, we landed on the Moon.
In contrast, it took four billion years to go from single-celled life, to the pyramids.
The odds of us being first by happenstance are astonishingly small. It's much more likely that either we are unique, or that civilizations don't leave much of a trace outside of their solar systems, regardless of whether or not they die out in the blink of a cosmic eye.
You must complete energy collection on current planet for XP to advance to level 2.
Anyways, let's assume life originated at some other planet and it has started life at half of the galaxy at the time it reached earth (so we weren't lucky to be "close" to the origin).
Earth is 4500 million years old, and life is assumed to have existed here since 4400 million years. So intelligent life took 4400 million years to "develop" here on earth. Light speed allows you to colonize the milky way comfortably within a million years. What if it takes 100 million years less on some other planet? Or it took just 10 million years less?
Either earth is very close to the real origin (or has been at the start of life), or the filter is in the past, or some other explanation.
I don't buy it though -- we're in an average planet on an average star, nothing about our environment seems to be particularly rare.
There are a number of Earth's attributes that we don't understand and have poor extra-solar data on. Particularly, the following:
Technically active plates after 4.5 Byrs. Effective magnetic core after 4.5 Byrs. Large amounts of surface water, presumably from our late heavy bombardment. Small enough to leave with a chemical rocket while meeting the above.
Also, at our current tech level, planets are very hard to even observe for existence, let alone their geographical features.
We simply don’t have data to support that claim, and the parameters required to make earth habitable for life (as we know it) are vastly more numerous than most people acknowledge.
So there may be millions of civilizations that can get into orbit with chemical or nuclear rockets, but not a single one that can carry out a megaproject that could be seen from Earth.
I wouldn't call the universe very old. It's only like 13.x billion years old. If you take into account the amount of time it takes for heavier elements to be created, the time for the universe to settle down I'd say we are in the first cohort. It took us 4.5 billion years to evolve and if humanity got wiped out life on Earth would most likely continue on as it has for millions of years before with megafauna.
Looking at how life appeared immediately after the planet cooled down and had liquid oceans most likely indicates abiogenesis is common, multicellular may be much more rare and intelligence probably is exceedingly rare given how expensive big brains are. I just don't think there was enough time in the early universe for intelligent civilizations to have evolved.
- The filter is ahead us
- There is no filter
- The filter is behind us, but ahead of the other planet
- Both planets have successfully got past the filter
We'll still be debating :). Then we'll go crazy trying find evidence of life in more planets.
- We're one of the first nearby and we're going to help build a filter
The various AI we give birth to over the next two centuries are going to dominate several galaxies. There are many filters - competing standards - throughout the universe, our galaxy doesn't yet have one. Humans will cease to exist as we think of them now, within those two centuries (and not due to climate change or any other similar event).
if we detect life so near to us and _yet_ we still have yet to encounter life from another planet means there's likely still _some_ kind of filter. So I don't think the likelihood of no filter is high if we detect life
according to [wikipedia](https://en.wikipedia.org/wiki/Great_Filter):
> So by this argument, finding multicellular life on Mars (provided it evolved independently) would be bad news, since it would imply steps 2–6 are easy, and hence only 1, 7, 8 or 9 (or some unknown step) could be the big problem.[4]