And I think it relates to what DGX and I were saying about the differences in biology and perception. Would the aliens even be looking for planets that could sustain life based on our parameters? (sun, atmosphere, water, food sources).
So yeah, they see some movement and change on the surface of a planet, does that encourage them to come down for a peek? I say probably if only to categorize us and move on.
Exactly...take some of the episodes of Star Trek for example, because Gene Roddenberry was really a visionary on things like this when you look back. How many times did the Enterprise come upon a planet and think it was uninhabited because they showed no signs of life? But that was because they were only searching for life as they understood it. That would eventually be the same way with us if we can conquer interstellar travel and possibly the same with alien races that already are capable of interstellar travel. As carbon based life forms, that's exactly what kind of life we would be scanning for, life that we know and understand. Life based on any other element would completely off our charts of understanding.
Not to mention one of my all time favorite movie scenes. Independence Day with people waiting on top of the building with welcome signs, and then BOOM
All aliens are cute and friendly
As mentioned, even ships being made of shiny metal is likely just us projecting what we think their ships should look like. (90% of UFO pictures)
Something tells me if they can travel 671 million miles per hour or better (light speed), they won't be in crafts made of steel and rivets
Do I think it's likely life exists on other planets? Yes. Intelligent life? Possibly. Have they visited us? Unlikely.
The reason I feel so is mainly because of the circumstances here on Earth that allowed life to evolve. A lot of which has to do with the impact that created the moon.
Because of this we have a large molten core that's larger than most planets around this size, the core gives us a strong magnetic field to protect us from harmful space radiation while letting just enough through for small genetic mutations to occur over time. The moon is over sized for the planet giving us much protection from asteroid strikes that would have otherwise wiped out much of the life on the planet way more frequently than has occurred. Also the large moon gives us strong tides that were likely a key factor in early life and still sustains the ocean currents that much advanced life relies on. Plus the moon gives us a stable rotation, without it or with a smaller captured moon the planet would likely wobble so much that no where on the planet would have a stable enough climate for intelligent life to evolve.
TLDR: While there may be billions of planets that are in the "Goldilocks zone", there are many other determining factors for life to advance to the point of interstellar travel. While possible, the likelihood of one of those planets finding us in the universe is slim.
Hal-9000 (08-07-2017)
I think of time as well. Our lifespans could be so short comparatively to an alien culture, that our entire history of existence is a blip in their perception. So that would allow what you're saying, that we've had time to evolve.
We have to be pragmatic and think, if they did want to contact us or visit, we would have definitive proof by now. The 'shy alien' theory just doesn't make sense.
One theory I've always found fascinating (and probable) says, that when we do get to the point of manned interstellar travel, most likely to Alpha or Proxima Centauri, the people that left first won't be the first humans to reach it, because in the time it will take them to get there, technology will have advanced far enough to get people there in far less time, so they will end up being 'passed' along the way (or possibly picked up on the way.).
That's pretty cool to think about. Science says those long journeys on movies have to become a reality where people are put in suspension pods. We just don't have the tech to reach the goal in less than X-amount of years. And as your theory outlines, in the decades or centuries the initial journey takes, we will have had time to create new ways.
I wish I bookmarked a link I had a few years ago. In was a Nasa guy who worked at the JPL lab and had a pretty high IQ. He was a bit gloom and doom as his prediction was based on one of my pet fears, Earth's population explosion problem over the next few years. Essence was he said we HAVE to find a way to move because the Earth will run out resources before we agree to start culling the population instead to survive. He said we won't have enough time to develop the tech necessary to ferry millions of people from the planet, so a lottery system will allow for a few ships to leave in a one time effort, while the rest of the planet dies. Keep a happy thought eh?
Yea, even if we had tech that had instantaneous light speed travel it would take over 4 years to get there. Any standard propulsion would be years of accelerating and years of decelerating and would be decades of travel time.
Reminds me of a series of Scifi books, I think by Niven. We've colonized the moon and the asteroid belt and those communities have become self sufficient and snub the earthers because of the pollution and no population control. Pretty much the planet had become a leech to off world colonies.
Another point I've read is - What would the alien's interest be in Earth? If they don't use the same tech to travel, they likely will have no need for our metals or resources. Water could be a consideration, but again that's dependent on the aliens having a similar physiology to us. If they need a place with atmosphere to live and breathe, surely there are planets closer to their home.
With the distances, I keep getting the sense that entire alien civilizations have come and gone. Even if they did appear in a ship one day I suspect we'll do the exact same thing we see in movies. Try to communicate, then consider them a threat, then try to destroy them.