I suspect the sheer size of Space is a key factor. It doesn’t seem to be considered in any of the explanations.
The likelihood of other civilizations arising may be high, but they will probably be far away from us. Assuming that ‘Star Trek’ warp drive remains fictional, they cannot communicate or travel faster than the speed of light. And interstellar travel at even a fraction of that speed represents an enormous investment of resources, which no civilization could commit without evidence that cannot be gathered faster than light speed. Could a civilization even survive long enough to send a signal and get an answer?
The volume of space (and the probability of a civilization that is within our communication reach) scales with the cube of distance. But the reverse also applies – the chance that they would choose to visit us, versus any other planet within their radius, also scales with the cube. And of course there is a huge jump from possible civilizations within our own galaxy (ie inter-stellar) to civilizations elsewhere (intergalactic), where the distances are vastly larger.
It needs a mathematical analysis that is beyond my expertise, to consider how these factors might play out. But intuitively it seems easy to imagine that the universe is too big, and life too sparse, for any meaningful contact to be established.
I think many of these more exotic ideas ignore the question on how these beings could evolve. Intelligence is not going to suddenly appear at random, you need some process like evolution that lets it happen in small steps. This means beings that reproduce, and for whom intelligence has a survival value.
I am beginning to think there are only humans, i mean right now with global warming we are talking about 2 degree rise being enough to kill most other life on our world, we allways talk about how stable the earth is, but it is also unstable with our big moon, is warm with are over abundance of radioactive isotopes, how we have the rock catcher Jupiter to save us from roids and how Jupiter is in the wrong place and had travelled out beyond us.
I think the grate filter may just end up being the composition of your solar system, there seems to be so many uniq/ unlikely things that makes up are one, that there may only be humans, we know for us life started in the oceans, and that they are moving around all the time, being dragged around our world by are large moon, larger that it should be for the size of our world, so if you live on pond planet with no moon so no tides, is your ocean world stagnate and dead, with out the moon to churn your seas and mix your elements round, how is life starting, or is there life, but its just gets hit by so many asteroids that it never gets started, Jupiter saves us from so much and what Jupiter misses well, look at the moon, its doing a prity good job…
Ultimately i am more than willing to say, we simply wont know in our life times, and will prob need to go stand on a few worlds not in our sol system to ever really know the answer.
I dunno…anytime I read something like “Light speed isin’t possible” I immediately think of headlines like “Many will never fly” or “Man will never travel to the moon”…
See, I like that one. If you take the lightspeed barrier as a given, what other kind of creature could travel interstellar distances other than one with such a low clockspeed we’d mistake it for a rock?
Reasonable skepticism. However, given the pretty long list of barriers in the known laws of physics to this, I’m feeling pretty confident that this one is a lot safer than the rest
My favorite of those is that as you approach light speed your propulsion system is also experiencing time dilation. As this is happening its mass would climb towards infinity, and the energy required to accelerate would also climb towards infinity.
