I see your point about not wanting to find life on Mars or Europa, as it would imply our great filter is before us, but I have a couple of reservations about that. First, it matters quite a lot what kind of life we might find. Is it a second genesis, a lifeform completely distinct from our own, or some distant relative? If it falls within the known boundaries of our phylogenetic tree of life - bacteria, archaea, and eucarya - it is likely derived from the same source. This would imply that either life formed on one of these worlds and spread throughout the solar system, or that it arrived here from elsewhere. That could mean that it's still a relatively localized phenomenon, and the great filter could be behind us.
If its entirely unique, it means that life is likely common and it could mean the great filter awaits it and us as you say. That could be troubling, but even so, I would be thrilled to hear of it. It might mean that the life we know is doomed to eventually die off due to an unknown great filter, but isn't that the case regardless? The life of the universe is finite, and so is any life held within it. Life has no ultimate purpose, it just is. It will spread and find root as long as it finds a nourishing environment, but will eventually come to an end. In my mind, life itself isn't the end goal. Understanding is. If there is life elsewhere in the universe, that enriches my understanding of what the universe is all about. I welcome whatever it brings.
Essentially, it boils down to this. Our timing is exquisite. The universe is already thirteen point eight billion years old. Despite this, it is unlikely other complex civilizations have had a chance to evolve. The environment was just too hostile. The early stars constantly blew up. After all, this is where all of our heavy elements came from. Galaxies would crash into each other and supermassive black holes emitted massive amounts of radiation. All of this effectively sterilized the early universe over and over again. Our sun - formed from the remnants of this chaotic and destructive early universe - came into being right at the end of this period. Conditions therefore could not be more fertile for life than they are now. Life evolved on earth pretty much as soon as the oceans formed. However, it took two billion years for single-celled organisms to evolve into multicellular organisms and another two billion for us to arrive. On how many other worlds has this happened? How often do bacteria progress to building spaceships?
I think the great filter idea is whack. First of all the only radio transmissions we could detect would be extremely powerful signals *deliberately* sent by aliens to advertise their presence. Radio noise from Earth is far less than radio noise from the sun and so noise is not something we would detect.
We have yet to analyze the atmosphere of an extrasolar planet that is earth sized. I am beginning to doubt that we will be able to do so with an actual Earth-like planet (Earth sized orbiting a G star in the habitable zone) in my lifetime. Looking at what we know now, I estimate the closest Earth-twin, when (if) such a thing is discovered would be more than 50 light years away.
Any journey to such a planet will take a long time, meaning the crew of such a ship would be *living in space* for most if not all of their lives. The crew would, in effect, be a space-dwelling culture. But a space-dwelling culture has no use for a planet, and so would have no interest in going to one.
The only people interesting in other planets are planet-dwelling culture. If we could do so in a journey lasting a fraction of our lives, we could make such a journey will remaining a planet-dwelling people. The same should be true of aliens. The Fermi Paradox thus provides strong evidence that faster and light travel is not possible.
I see your point about not wanting to find life on Mars or Europa, as it would imply our great filter is before us, but I have a couple of reservations about that. First, it matters quite a lot what kind of life we might find. Is it a second genesis, a lifeform completely distinct from our own, or some distant relative? If it falls within the known boundaries of our phylogenetic tree of life - bacteria, archaea, and eucarya - it is likely derived from the same source. This would imply that either life formed on one of these worlds and spread throughout the solar system, or that it arrived here from elsewhere. That could mean that it's still a relatively localized phenomenon, and the great filter could be behind us.
If its entirely unique, it means that life is likely common and it could mean the great filter awaits it and us as you say. That could be troubling, but even so, I would be thrilled to hear of it. It might mean that the life we know is doomed to eventually die off due to an unknown great filter, but isn't that the case regardless? The life of the universe is finite, and so is any life held within it. Life has no ultimate purpose, it just is. It will spread and find root as long as it finds a nourishing environment, but will eventually come to an end. In my mind, life itself isn't the end goal. Understanding is. If there is life elsewhere in the universe, that enriches my understanding of what the universe is all about. I welcome whatever it brings.
There is also the possibility we are just early.
https://amturnbull.substack.com/p/we-are-early-probably
Essentially, it boils down to this. Our timing is exquisite. The universe is already thirteen point eight billion years old. Despite this, it is unlikely other complex civilizations have had a chance to evolve. The environment was just too hostile. The early stars constantly blew up. After all, this is where all of our heavy elements came from. Galaxies would crash into each other and supermassive black holes emitted massive amounts of radiation. All of this effectively sterilized the early universe over and over again. Our sun - formed from the remnants of this chaotic and destructive early universe - came into being right at the end of this period. Conditions therefore could not be more fertile for life than they are now. Life evolved on earth pretty much as soon as the oceans formed. However, it took two billion years for single-celled organisms to evolve into multicellular organisms and another two billion for us to arrive. On how many other worlds has this happened? How often do bacteria progress to building spaceships?
I think the great filter idea is whack. First of all the only radio transmissions we could detect would be extremely powerful signals *deliberately* sent by aliens to advertise their presence. Radio noise from Earth is far less than radio noise from the sun and so noise is not something we would detect.
We have yet to analyze the atmosphere of an extrasolar planet that is earth sized. I am beginning to doubt that we will be able to do so with an actual Earth-like planet (Earth sized orbiting a G star in the habitable zone) in my lifetime. Looking at what we know now, I estimate the closest Earth-twin, when (if) such a thing is discovered would be more than 50 light years away.
Any journey to such a planet will take a long time, meaning the crew of such a ship would be *living in space* for most if not all of their lives. The crew would, in effect, be a space-dwelling culture. But a space-dwelling culture has no use for a planet, and so would have no interest in going to one.
The only people interesting in other planets are planet-dwelling culture. If we could do so in a journey lasting a fraction of our lives, we could make such a journey will remaining a planet-dwelling people. The same should be true of aliens. The Fermi Paradox thus provides strong evidence that faster and light travel is not possible.
You mean intelligent life. I have high hopes for life in the under ice oceans of Jupiter's and Saturn's moons.