Our definition of life only depends on what has been observed on Earth. Until we find life on another planet, or in another solar system, we are limited to observing what we know about life, only to what we have here on Earth. Simply speaking, our sample size for what life is, is limited to just one area, albeit, many different forms and species are included in this one sample of how life can emerge on a planet.
It is possible that there are life forms or organisms that have emerged in the far reaches of our Universe, that do not conform to our current accepted definitions of life. These creatures may be chemically, biologically, and even anatomically different than any life forms that exist on Earth. It is also possible that they have put together societies and technologies to the extent of human industrial development. In this case, we may have to update our definition of life to include this hypothetical
Modifying the definition of life to
include other organisms that may be found elsewhere in the universe, could be an interesting proposition to modern scientists. They may not be as eager to take new evidence into account, especially if the evidence goes against the general characteristics of live that have been widely accepted amongst members of the scientific community. There is no guarantee that we will ever find life similar to what is on Earth outside of our own solar system, and whatever we may find, may be life, but not be at all similar to what we have here on our home planet.
Another thing to consider, is what our goal is in exploring our solar system, and others around us. Because of the current state of energy consumption on Earth, our planet is quickly becoming less habitable, and it is possible future generations will not be able to live sustainable lifestyles here. In order for the human race to survive, it may be necessary to find another planet drastically similar to Earth, to populate further. Also interesting to consider is, if we find a planet with very similar habitability requirements to Earth, will there already be life on it?
I like how you brought up that Earth, many different types of life, is only one small sample size compared to the whole universe and that our sample for life could be completely different than another sample that might be out there.
However, even if we do find another planet that has life just like Earth, it would probably take a very long time before we even have the ability to physically get there. It might not even be possible for humans to travel to another Earth-like planet before we eventually have an inhabitable planet.
I totally agree that our knowledge of life is very limited due to earth being the only planet we know that hosts it. You can’t really define what life is because it could literally be anything for all we know, but if we do discover something in deep space than that would definitely better our understanding. I also agree that humans need to figure out a way to travel and inhabit other planets because our resources are limited and we wont be able to stay here much longer.
The hard part is how will we know something is life when we see it? Since there is no clear definition, since we are limited to life on earth, it will be hard to classify an extraterrestrial substance if we happen to find one.