So about panspermia…

So @John_Harshman, do you think extraterrestrial life is likely?

All the article says is that red dwarfs are not likely to harbor life. How does this affect panspermia or the prospect of alien life? Our star is not a red dwarf, and there is life.

It just seems as though the stars, formerly thought to be likely to foster / harbor life, may not do so. So in dramatically reducing the number of stars where life could potentially originate, does it not also reduce the chances of life originating and then spreading?

Red dwarf stars have been seen as the biggest potential frontier for alien life, in part because they’re the most common stars in our galaxy. But observations made using the Hubble Space Telescope suggest that the frontier might turn out to be a desert.

Red dwarfs, or M-dwarf stars, are much smaller and dimmer than our sun — but they’re thought to account for 50 to 75 percent of the stars in our Milky Way galaxy.

“The Earth, we know, formed ‘dry,’ with a hot, molten surface, and accreted atmospheric water and other volatiles for hundreds of millions of years, being enriched by icy material from comets and asteroids transported from the outer solar system,” another Hubble co-investigator, Glenn Schneider of Arizona’s Steward Observatory, said in a news release.

Grady said red dwarf seem likely to miss out on that part of the process.

That sounds suspiciously like the argument for the rarity of functional protein folds. :wink:

We don’t know all the possible ways life might be supported or might exist, therefore we cannot make any inferences at all.

Ever notice how the anti-ID crowd seem rather confused about what we can know and how we can know it when it comes to design arguments but have no problems at all when it comes to evolutionary arguments.

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If they were living and came from Earth ‘ejecta’ that would be panspermia. That’s pretty much what the term ‘panspermia’ covers. But they could also be abiogenesis (originated on Mars) or panspermia from elsewhere. The same applies for Earth life.

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Admittedly, I don’t know how probability affects this argument and what aspect is opinion vs. fact. It seems that with much less opportunity for life, there’s much less opportunity for life to be spread. But we could have all won the lottery several times over, too. So, I’m not being snarky at all about it, just asking and hoping to understand.

I think that many people tend to think of panspermia in terms of aliens purposefully seeding life, so the aspect of ‘ejecta’ gets ignored. But when considering ‘ejecta’ that would have originated from outside of our solar system, assuming we were able to learn with certainty that life did not spontaneously originate anywhere within our solar system), would not the issue brought forth in the linked article be appropriate? Obviously ‘ejecta’ would travel relatively slowly, so the distance from another star, friendly to life, would seem to increase based upon the fact that fewer such stars may be available. Is that so?

I was surprised to read that stars move around a lot more than I thought. In the next 15 million years a total of 694 stars will come within 16 light years of Earth. Red dwarf stars make up 85% of the stars in the Milky way, so that comes to about 100 non-red dwarf stars that will swing through our neighborhood in the next 15 million years. If we assume this is the normal rate, then that is 6,000+ non-red dwarf stars that would have gone by our solar system per billion years. If we look at the Milky Way as a whole, there 15 billion non-red dwarf stars.

That is very interesting. It would also be interesting to note at what speed a chunk of planet containing life would travel and how that might translate in terms of time.

So, because you have researched the number of potential stars, are you also under the impression that probability comes into play? That was really my initial question. Since you are suggesting that the number is not so small, I’m assuming that you are confirming this (at least your opinion?)

It would most likely be a grain of sand or some other planetary dust.

Great. A very small rocks… (See Monty Python…) How fast might it travel?

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Hearts for any post that mentions Monty Python.

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Very fast. Solar wind would propel it out of the stellar system extremely fast.

I have no way of knowing how to even start those probabilities. However, there is an obvious problem with confirmation bias since we are looking at results after they happen. It is going to be rather difficult to get an accurate distribution for life in the universe.

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I find it interesting that extraterrestrial life is a relatively common subtopic of the Creation v. Evolution Debate…I suppose the idea of extraterrestrial life does bring up important questions (in addition to having significant implications) regarding origins (implications/questions that are are probably not commonly considered by the average Star Wars fan :wink: ).

Suffice it to say, I would find the discovery of extraterrestrial life that didn’t originate on Earth (especially intelligent extraterrestrial life) to be very surprising (not to mention unlikely), and I am disinclined to believe that it exists (although it may be an interesting topic to discuss). That would be my 2 cents worth (or two paragraph’s worth). :wink:

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Right back at ya! :slight_smile:

What is the airspeed of an unladen meteor?

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What do you mean, an African meteor or a European meteor?

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I’m crushed, I stepped away and missed the opportunity. Nice work, Horton. Nice work, indeed. :slight_smile:

Kudos, @Argon, for the setup!! :slight_smile: See, it does take a village…

Gotta be quick around here Mike. :wink:

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