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More evidence is consistent with possible ancient life on Mars (2025)

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Re: More evidence is consistent with possible ancient life on Mars (2025)

#121

Post by stackghost »

pfdietz wrote: post #120
red-iron-pine wrote: post #118

Earlier quoted context omitted.

while that's possible, it's also likely to burn the hell out of anything in / on / around. any would-be hitchhikers would need to be able to survive extinction-ish level impacts on Mars, survive through the vacuum (e.g. months), and then survive atmospheric re-entry and landing. and then be able to survive in the new ecosystem

Certainly a great deal of energy is released. However, on the time scale of an impact, heat doesn't diffuse in rock very far. Even on the time scale of reentry to an atmosphere heat doesn't diffuse far. It's common for a meteorite that has fallen to Earth, despite the surface having been melted and ablated, to have an inside that is still freezing cold.

Ah, this was the piece I was missing. I assumed the heat of impact and/or re-entry would sterilize just about anything that wasn't an engineered heat shield.

Re: More evidence is consistent with possible ancient life on Mars (2025)

#122

Post by pfdietz »

stackghost wrote: post #121
pfdietz wrote: post #120

Earlier quoted context omitted.

Certainly a great deal of energy is released. However, on the time scale of an impact, heat doesn't diffuse in rock very far. Even on the time scale of reentry to an atmosphere heat doesn't diffuse far. It's common for a meteorite that has fallen to Earth, despite the surface having been melted and ablated, to have an inside that is still freezing cold.

Ah, this was the piece I was missing. I assumed the heat of impact and/or re-entry would sterilize just about anything that wasn't an engineered heat shield.

The concern in the impact is how much heat is produced in the material itself, by the shock wave. A shock wave is dissipative, producing entropy and heat as it propagates, but near the spalled surface it cancels itself out and the heating becomes small.

Re: More evidence is consistent with possible ancient life on Mars (2025)

#123

Post by raychis »

blamestross wrote: post #110
raychis wrote: post #2

The article is good but the title is a bit too slippery a statement in my opinion. The article is saying more evidence is consistent with possible ancient life on Mars. In astrobiology the massive problem is that geology can imitate biology. The presences of minerals formed by microbes on Earth does not prove microbes are involved in their production on Mars, it is a big jump to make.

We have long passed at least my owner personal "threshold of evidence" to assume that Mars had life. That bar is pretty low. I am not hard to convince. We don't have a baseline by which to contextualize the situation statistically. There is no p-value we can meaningfully satisfy. Worse than that, evidence required for a belief derives from the risk of being wrong. Is there a discussion of what evidence WOULD be enoug…

The bar for scientific discoveries is generally incredibly high and rightly so. In particle physics for example for a discovery to be confirmed it must be independently verified by a second experiment and both the discovering experiment and confirming experiment must be within five standard deviations (or a roughly 1 in 3.5 million) chance of not being a discovery. Its not a perfect comparison because astrobiology is messier but it is useful to see how high the bar is.

For a discovery of the magnitude of life outside our planet the scientific community would probably need something like: a real and well-characterised signal, multiple independent lines of evidence, strong geological context, replication by independent teams, and a serious failure of plausible alternate explanations. Until then, “potential biosignature” is probably the right phrase.

To be clear, I think like you that there probably was life at some point on Mars. I am pretty convinced. But, you and I being pretty convinced does not come close to the threshold of a scientific discovery.

Re: More evidence is consistent with possible ancient life on Mars (2025)

#124

Post by microgpt »

raychis wrote: post #123
blamestross wrote: post #110

Earlier quoted context omitted.

We have long passed at least my owner personal "threshold of evidence" to assume that Mars had life. That bar is pretty low. I am not hard to convince. We don't have a baseline by which to contextualize the situation statistically. There is no p-value we can meaningfully satisfy. Worse than that, evidence required for a belief derives from the risk of being wrong. Is there a discussion of what evidence WOULD be enoug…

The bar for scientific discoveries is generally incredibly high and rightly so. In particle physics for example for a discovery to be confirmed it must be independently verified by a second experiment and both the discovering experiment and confirming experiment must be within five standard deviations (or a roughly 1 in 3.5 million) chance of not being a discovery. Its not a perfect comparison because astrobiology is…

We can say we discovered signs there might've once been life on Mars

Re: More evidence is consistent with possible ancient life on Mars (2025)

#125

Post by jibal »

jibal wrote: post #70
gilrain wrote: post #63

Earlier quoted context omitted.

Because honorary degrees are not credentials.

But that's obviously not a reason to treat them as a bad thing. It's also not entirely true ... he was awarded those honors because of the quality of his science journalism. FWIW, I think @mapontosevenths is wrong to say that @gojomo's mention of the honorary degrees and being an OOC was "like they're a bad thing" ... their "But it's hard ..." indicates a conflict between those "credentials" and the typo that gojomo…

So many people here have no idea how things work and are far more interested in virtue signaling over an error (and making spiteful downvotes) than in correcting it, so we get ignorant and intellectually dishonest rubbish like

> I think readers should take this as an illustrative example of how often people/institutions draped in such quasi-credentials are carelessly wrong on basic things.

and

> how many people had to be asleep at the wheel for the truth-reversing error to get published, & persist for months? Does no one at the CBC – with pride in its work & any familiarity with these topics – read CBC's slop?

I, OTOH, sent them a note and they quickly fixed the article. Errors like this "persist for months" simply because no one takes the time for such a simple action when they encounter an error ... I'm the only person among those who commented here who did so. And no, of course no one at the CBC or anywhere else spends their time rereading their months-old articles to see if some error made its way in.

Re: More evidence is consistent with possible ancient life on Mars (2025)

#126

Post by pigpop »

slfnflctd wrote: post #108
pigpop wrote: post #60

Earlier quoted context omitted.

I don't see why an intelligent alien species would have similar values to us. It would depend entirely on their social organization so unless they were the exact equivalent of us evolutionarily (omnivorous, sexually dimorphic, social, bipedal, terrestrial, etc.) they would value the lives, property, territory and status of their own kind and other animals very differently. A race of aquatic arthropods could be mostly…

I see someone else recently read Children of Strife . Damn, I really enjoyed that book. Best of the series so far, in my opinion.

Actually I haven't but I'll check it out.

Re: More evidence is consistent with possible ancient life on Mars (2025)

#127

Post by pigpop »

throwaway676712 wrote: post #88
pigpop wrote: post #60

Earlier quoted context omitted.

I don't see why an intelligent alien species would have similar values to us. It would depend entirely on their social organization so unless they were the exact equivalent of us evolutionarily (omnivorous, sexually dimorphic, social, bipedal, terrestrial, etc.) they would value the lives, property, territory and status of their own kind and other animals very differently. A race of aquatic arthropods could be mostly…

A necessary condition for the emergence of civilization (in its broadest sense, as in the collectively organized reshaping of one's living environment for one's purposes) is a basic level of trust and cooperation. Humans are not naturally prone to bouts of violence like other species and human societies do not tolerate impulsive violence in adults. Instead, the vast majority of human-on-human violence is deliberate:…

>Humans are not naturally prone to bouts of violence like other species

That... does not check out. There are plenty of violent people, I've met many.

Re: More evidence is consistent with possible ancient life on Mars (2025)

#128

Post by pigpop »

altmanaltman wrote: post #96
pigpop wrote: post #60

Earlier quoted context omitted.

I don't see why an intelligent alien species would have similar values to us. It would depend entirely on their social organization so unless they were the exact equivalent of us evolutionarily (omnivorous, sexually dimorphic, social, bipedal, terrestrial, etc.) they would value the lives, property, territory and status of their own kind and other animals very differently. A race of aquatic arthropods could be mostly…

I mean could a race of aquatic arthropods ever organize in scale enough to be a species that can travel light years and invade others? Wouldn't they just eat each other and never have any need to build a community or to colonize space? We need to have some baseline for what we consider as "intelligent species" in this context and most intelligent species will need to have a system where they can pool their resources…

If you showed me a primate and I didn't have any knowledge of the existence of humans and then asked the same thing of them I'd also have to get creative about how they may evolve to be an intelligent society.

Re: More evidence is consistent with possible ancient life on Mars (2025)

#129

Post by pigpop »

TFNA wrote: post #87
pigpop wrote: post #67

Earlier quoted context omitted.

Comments like yours make me think that sci-fi shows (and a lot of literary sci-fi) like Star Trek did a grave disservice to our conception of advanced spacefaring civilizations. They were always focused on alien planets , assuming that once a race was able to travel the stars that they would still chain themselves to a gravity well. It's like imagining an industrial society where everyone still lives on a farm like t…

In his novel Aurora , Kim Stanley Robinson challenged this view by suggesting that at the small scale of orbital structures, there may be insurmountable obstacles to biological life, like the buildup of salt through waste. His ultimate conclusion was that “life is a planetary phenomenon” (and we should take better care of the planet we have).

If I remember correctly, the novel was concerned with a generation ship travelling to a distant star. This is not the same as space habitats in a solar system where there are plenty of sources and sinks for all materials involved in the maintenance of a habitat.

I think he modeled his habitats as large ecosystems as well in the novel. That's not strictly necessary and would simplify the design a lot.

Also, it was a fictional story so not the best source for information. Which is kind of proving my point about sci-fi messing up everyone's conception of what the future could hold.

Re: More evidence is consistent with possible ancient life on Mars (2025)

#130

Post by nephihaha »

nkrisc wrote: post #66
nephihaha wrote: post #42

Earlier quoted context omitted.

I don't think it was weak at all. We got two positive results from the Viking landers and then tried to explain them away. There is a lot of circumstantial evidence, which combined builds up a case. The public believe we should be looking for cities and skeletons, when in fact we should be looking for extremophiles. It is possible that some of these are due to cross-contamination within the solar system (before human…

Two positive results that had non-biological explanations and a lack of any other significant evidence. Extreme skepticism is warranted.

They are best thought of as circumstantial evidence, especially when combined with the various other possible indicators we have detected on Mars. Many books I have read over the years talk about the Viking experiments as if they had disproved life, whereas they did no such thing.

However, I think the bulk of life on Mars – if it exists – is probably underground. Conditions there are much less hostile than the immediate surface. Since Viking, we continue to find Earth life in extreme environments including high altitudes and deep underground. Microbes can be much tougher than animals.

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