Aliens and the Fermi Paradox 686
First time accepted submitter sayhem (1842674) writes Various explanations for why we don't see aliens have been proposed—perhaps interstellar travel is impossible or maybe civilizations are always self-destructive. But with every new discovery of a potentially habitable planet, the Fermi Paradox becomes increasingly mysterious. There could be hundreds of millions of potentially habitable worlds in the Milky Way alone. This impression is only reinforced by the recent discovery of a "Mega-Earth," a rocky planet 17 times more massive than the Earth but with only a thin atmosphere. Previously, it was thought that worlds this large would hold onto an atmosphere so thick that their surfaces would experience uninhabitable temperatures and pressures. But if this isn't true, there is a whole new category of potentially habitable real estate in the cosmos.
Re:Progenitors? (Score:4, Informative)
We're not even orbiting a 1st generation star, for FSM's sake.
Stars had lived their entire lives before ours even formed.
Re:Progenitors? (Score:5, Informative)
So given the size of the universe, we know from just here that there's definitely been life and intelligent life favorable conditions elsewhere just from the limited sample set we've collected.
[Citation needed.]
Until we have any actual evidence of life or intelligent life "elsewhere," we have absolutely no evidence that conditions "elsewhere" are sufficiently "favorable" for anything. It's all just speculation. The "sample set" is ONE instance, which is not statistically significant evidence for anything.
"Favorable" could be 1 in 10 planets, or it could be 1 in 100 quadrillion quadrillion. You can't conclude anything from a sample size of 1. (There's also not a lot of evidence AGAINST favorable conditions existing elsewhere, since we really can't know what "favorable conditions" are until we've enlarged our sample set, but that doesn't mean anything either.)
Re:Progenitors? (Score:4, Informative)
The problem with Drake's equation isn't the uncertainty - that's part of the assumption behind the equation. It's that it doesn't properly account for space & time. Let's say that the highest number is correct and that there are 100 million civilizations
In 4.6 billion year history of our solar system intelligent life has had the possibility of traveling to another star for 1.08695652e-8 of that time (that we know of anyway) - that means that of the 100 million civilizations less than 132 might exist at the same time and if distributed evenly would be 1 per 7.1969697e+15km of space. Meaning that our nearest neighbour might be 760 light years away. That means that if they just started transmitting at the same time we did, we won't pick them up for another 710 years. If they started 100,000,000 years ago those signals have long since passed us by and we likely don't have the science to pick up the more advanced signals that might be passing us by right now.
Re:Self destruction built into intelligent life? (Score:4, Informative)
People with auto-immune diseases aren't less susceptible to being killed by regular infections. That's usually what kills them.
Autoimmune diseases are an interesting problem where for some reason the chemical self/not-self signalling gets messed up, and the immune system starts attacking a host of identified "not self" cells. Other ones - like asthma - are a hypersensitivity of the primary (non-specific) immune response.
Cancer is the exact opposite problem: cancer is when you get a specific series of mutations which do not result in the normal cellular apoptosis mechanism destroying a body cell. The immune system doesn't target cancer because it doesn't target "self" cells. Cancer is immune-invisible, and the holy grail of cancer therapy has always been to find something unique about cancer cells that the immune system can be sensitized to to attack.
None of this is caused by some weird idea of "balance" of the immune system, and the way you used the phrase to start with was a weird thing to do with antibiotics and nature or something.
I suggest thinking hard about your positions before you start advocating withholding treatment from patients and letting people die, which is what you were trying to circumspectively say without sounding like a monster (also looking up the actual causes of antibiotic resistance and how drug-resistance evolves - it's really not what you seem to think).
Re:the joker in the formula (Score:4, Informative)
This has not happened once, it's happened multiple times in the Homo genus
Homo gautengensis
Homo habilis
Homo erectus
Homo antecessor
Homo ergaster
Homo rhodesiensis
Homo heidelbergensis
Homo neanderthalensis
Homo floresiensis
Denisova hominin
Red Deer Cave people
That's 12 species, including homo sapiens, though homo sapiens killed off or absorbed the other 11 (remember, Homo sapiens are upto 30% Homo neanderthalensis due to interbreeding). Homininae are close enough genetically and many have shown the ability to communicate that they, given the lack of human presence, could evolve to our state as well. That's another 39 species.
Also, while you're taking the past into account you're not taking the future. In 4.6 billion years whether you want to say 1 to 12 species evolved depending on how you want to frame it. The Earth has an estimated 5 billion years remaining... so lets say in the next 100 years, even a million years, there's an extinction event and primates all die. That's 4.9 billion years for another intelligent species to develop.