Seen this posted elsewhere as well, still sceptical, they only have one reference point, our solar system.
I'm not saying they're wrong, just more information is needed.
A new study suggests that having the right kind of asteroid belt in a solar system could be essential to finding intelligent life in the universe – including here on Earth. A team from NASA and the UK's Royal Astronomical Society has been studying the role of asteroid belts in the evolution of life on Earth and in the wider …
,I'm quite sceptical that it will ever be n<1 in our lifetime.
Don't you mean "n>1"? Because the fact that life happened won't go away, even if we (and all other life, sentient or not) totally cease to exist. It's just that no-one will be there to note that we have been there, that n=1.
"Seen this posted elsewhere as well, still sceptical, they only have one reference point, our solar system.
I'm not saying they're wrong, just more information is needed."
It's worse than that, they are basing the conclusion on 0 reference points. They are comparing 2 types of system, one for which they have 1 reference point, and the other type they have no reference points for. So they can have no valid comparison.
The Earth is approximately 4.7 BILLION years old. The Solar System is about the same. The entire visible Universe is approximately 13.7 BILLION years old. The Universe is not even THREE (3!) times older than the Earth. If life (and its "building blocks") can be explained in 13.7 BILLION years in the cold hard vacuum, then it can be more easily explained in 4.7 BILLION years given a nice warm puddle.
This sort of Panspermia theory is almost certainly unnecessary; i.e. extremely unlikely to be required. Those that push such nonsense should first prove that there's not a much simpler 'warm puddle' explanation. They almost need to prove that a cold hard vacuum is a required condition to boot strap life. Utter nonsense.
On the orther hand, if the Earth is only about 6016 years old, then the creation of life might require significant input from external forces.
Without a planet like Jupiter that reduces the rate of major impacts, planets inside the "Goldilocks zone" that have the right temperature and composition for life will get twatted by asteroid impacts far too often for any complex life to evolve.
Our Earth hasn't been hit by anything big for 65 million years, and prior to that it was probably another 200 million years or so.
Very early on the Earth got properly pasted though, being hit by something the size of Mars has gotta hurt!
Life first appeared on Earth about 15 minutes after the environment was stable enough to support it. The combined notions that it originated here so soon, and yet requires some miraculously special environment to do so requires a leap of faith. I ain't jumping. It's easier to believe space is littered with life and it sprouts in every fertile ground.
I am not so sure space is littered with life. The emergence of various novel features of life through evolution seems to have required long periods of brute force, so I suspect the same is true of the emergence of life itself.
For example to an outside observer watching the Earth it first seemed intelligence was increasing over time and peaking in large reptiles and mammals. But then things get stuck for 100 million years on such "dumb" animals. To the observer it might have seemed hopeless that anything intelligent would evolve. And frustrating because a higher intelligent species would dominate and flourish (as we have) but nothing was happening. Why wasn't evolution selecting for intelligence! Why were none of the dinosaur species for example evolving to become more intelligent? Then suddenly out of the blue a certain tree of mammals (apes) developed some serious intelligence and a particular branch boomed into an intelligent planet-dominating species.
Why so long? It must be because there were a number of obstacles that required mere chance to crack, and it took a vast amount of time for the right circumstances to crack them. If humans and apes disappeared from the planet I presume it could take hundred million more years for a new intelligent species to emerge.
Because things can emerge but don't emerge it seems things get stuck and life needs to "try a lot of things" to crack that combination lock. If you are brute forcing a problem you want to try many combinations, not keep trying the same thing. So I think reasonably frequent mass extinctions are a very useful thing to have on planets as they effectively force a reset event that wipes out the "failed" species and allows a new combination to be tried out. For example arguably if the dinosaurs hadn't been wiped out mammals would not have gained dominance and so humans would never have emerged.
Also I would think a larger planet would be able to try out more combinations because it can field more geographically diverse species and so is able to hammer away at the combination lock better. On a planet with 100x the surface area of Earth the chance of hitting intelligent life might be slashed by an order of magnitude.
Also a planet with very diverse conditions would be better as it could field many different niches. A planet in a binary star system may have a very weird climate setup, not simply latitude based temperature gradient like our own.
So I think the best planets for intelligent life to emerge will be big planets in binary systems that are frequently bombarded. Obviously I am just guessing though. There might be a good reason why a small planet like ours is better suited.
"Why were none of the dinosaur species for example evolving to become more intelligent?"
Is that really a given? Who's to say there were no intelligent dinosaurs?
Apart from the fact that it's likely a dinosaur intelligence would probably be quite different to something we might recognise 65 millions years after they were wiped out, one wonders how much of our civilisation might be identifiable 65 million years after a massive meteorite impact.
We also need to bear in mind that any possible dinosaur intelligence might not have evolved into a technological civilisation or might have been at the hunter gatherer stage when Dr Doom came calling so there'd not be any surviving evidence.
Mikel - "Life first appeared on Earth about 15 minutes after the environment was stable enough to support it. "
"Building blocks of life" raining down from the heavens is, at best, lunch.
I suspect that the Panspermia theory is based on a religious urge to have an external Creator, even if He is an complete Asteroid.
Can anyone explain how a planet can "spiral" into it's sun? As far as I'm aware, the only possible trajectories for any two interacting bodies are the hyperbla (common, the parabola (rare), the ellipse (commonn) and the circle (rare). A spiral would involve some way of shedding kinetic energy, and lots of it.
Indeed, crashing into asteroids or simply going close to them will affect the orbit greatly, acting to shed KE any time an asteroid is impact or slingshotted.
Aside from that the solar wind and photon pressure alters any non-circular orbit in a non-linear way - it's one of the methods being seriously considered for preventing a catastrophic asteroid impact.
There are a couple of factors which rather mess up the later comments. First, all objects in orbit will be orbitting in the same direction, so the differences in velocity will be minimal. Secondly, The orbit of a planetof the Jovian type will be little perturbed by low mass planets, and even less by objects with the mass of asteroids. The result of any collisions will only result in a new orbit, the size of which will be in proportion to the ratio of their respective masses.
That's odd, I can't seem to find the bit where they have conclusively proven that the star systems they studied that do not have stable asteroid belts, also do not have any form of intelligent life. I'm sure they must have done so, because otherwise it would just be worthless and idle speculation, not a study.......
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