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As of 2020, there is no widely agreed-upon evidence of extraterrestrial life, and we don't know if there will ever be. But suppose for a moment that humans do, in your lifetime, find indisputable evidence that life is not limited to planet Earth. What do you think is the most likely form this evidence will take?

Do you think it will be primitive lifeforms (e.g. bacteria, algae, worms) under the ice of Mars or Europa?

Or do you think it will be an interstellar transmission from a civilized species?


As for myself:

The wide variety of extreme environments on Earth show us that as long as there's energy to exploit there's life. I'd say it's a safe bet that we'll find alien microorganisms somewhere.

I doubt we'll get any transmissions though, even supposing aliens capable of it exist. Here on Earth we're moving away from using broadcast signals that go far into space. Anyone sending anything would have to be actively trying to do so, and as I understand there'd be plenty of problems with signal degradation.

In my lifetime I doubt I’ll see any missions to Europa, and a half-assed, pointless for anything but propaganda mission to Mars at best. So, I guess by default I’m on Team Transmission.

There are multiple Mars missions on the way right now, and more in the planning stages. Propaganda or not, that's happening, and targeting more likely areas for micro-organisms (or their remnants) is definitely on the list.

https://www.space.com/three-mars-missions-launch-july-2020.html

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If there were alien communications flying around, I think we'd have caught them by now, given all our technology.

I think you're overestimating our tech base or under-estimating the scale of the galaxy. Or both.

As far as we know, faster than light is non-viable, so any 'space-faring' civilizations are going to operate in very localized clusters. The odds that one (or even a post industrial one) is near us is pretty poor.

I recon they going to bring some crap back from mars and it will be similiar to the move "Life"

The missions to retrieve the samples are on their way..

"The surest sign of intelligent life in the universe is that none of it has tried to contact us." -Calvin

 ScarletRose wrote:
The wide variety of extreme environments on Earth show us that as long as there's energy to exploit there's life. I'd say it's a safe bet that we'll find alien microorganisms somewhere.

I doubt we'll get any transmissions though, even supposing aliens capable of it exist. Here on Earth we're moving away from using broadcast signals that go far into space. Anyone sending anything would have to be actively trying to do so, and as I understand there'd be plenty of problems with signal degradation.

I’d been thinking that too recently; high power wide area transmissions are too inefficient and inflexible. Given the current trends on streaming, fibre broadband and low power 5G, it’s highly likely that in 20 years we will have abandoned traditional TV and radio transmissions, which are the big culprits for off-world detection. If you assume that other technological civilisations would follow the same arc, the you only have a window of ~150 years in which to detect them. The chances of other intelligent life existing at the same time as us are fairly low. The chances of them being at the exact same point in technological development and within detection range with such a narrow time window is vanishingly small, unfortunately. I think SETI need to start looking at ways to detect non-transmitting technological civilisations, as that’s much more likely; spectroscopic analysis of exoplanet atmospheres perhaps?

 Jadenim wrote:

I’d been thinking that too recently; high power wide area transmissions are too inefficient and inflexible. Given the current trends on streaming, fibre broadband and low power 5G, it’s highly likely that in 20 years we will have abandoned traditional TV and radio transmissions, which are the big culprits for off-world detection. If you assume that other technological civilisations would follow the same arc, the you only have a window of ~150 years in which to detect them. The chances of other intelligent life existing at the same time as us are fairly low. The chances of them being at the exact same point in technological development and within detection range with such a narrow time window is vanishingly small, unfortunately. I think SETI need to start looking at ways to detect non-transmitting technological civilisations, as that’s much more likely; spectroscopic analysis of exoplanet atmospheres perhaps?

Radio transmissions from Earth are so weak that they'll be basically below background radiation before reaching less than 1% of 1% of the stars in our galaxy. So you not only have a super short window of galactic time to deal with, they have to basically be next door to us to have a chance of detecting them.

 Jadenim wrote:

I’d been thinking that too recently; high power wide area transmissions are too inefficient and inflexible. Given the current trends on streaming, fibre broadband and low power 5G, it’s highly likely that in 20 years we will have abandoned traditional TV and radio transmissions, which are the big culprits for off-world detection. If you assume that other technological civilisations would follow the same arc, the you only have a window of ~150 years in which to detect them. The chances of other intelligent life existing at the same time as us are fairly low. The chances of them being at the exact same point in technological development and within detection range with such a narrow time window is vanishingly small, unfortunately. I think SETI need to start looking at ways to detect non-transmitting technological civilisations, as that’s much more likely; spectroscopic analysis of exoplanet atmospheres perhaps?

SETI has projects looking at other signatures of intelligent life, not just radio waves. The idea of using lasers to send a message has been around for decades, and there have been some attempts to try and spot these over the years.

There have also been attempts to observe physical evidence, from contaminants like pollution or nuclear waste in exoplanet atmospheres, alien probes (or, dare I say it, monoliths) located near to the Earth, megastructures in orbit around other stars, or even manipulation of things like stars and black holes. Obviously, some of these don't get a lot of publicity for fear of ridicule, but the megastructure hypothesis did come up in at least one exoplanet paper to explain an unusual pattern of observations.


Automatically Appended Next Post:
I voted alien communication, although I'm probably 50:50 at present until we make serious efforts to find life on the outer planets.

I think we'll find evidence of at least past life, and likely some current bacteria and lichen-like life on Mars, but it won't be conclusive proof of life elsewhere. Mars and Earth have too much cross-contamination. We'll need to go to places like Enceladus, Europa, maybe even Pluto to guarantee life could and did spring up independently.

Micro-organisms outlive civilized societies by far, existing both before and after them. If we can find millions of years old micro-organisms from our own ocean floors, I have very little doubt that we could find them also on other planets such as Mars.

as a proponent of the great filter theory, with the expectation that the filter lies infront of us instead of behind us, i seriously doubt either type of evidence.

At most we find as stated above hints of past live, mostlikely within microorganisms.

My bet is on microorganisms within our own system. With the hottest candidates being the icemoons of Jupiter and Saturn like Europa that have liquid oceans underneath their surface and/or Titan with some weird methan "breather".

I also would not be surprised if we found some microbial contamination on one of the Mars missions manages to survive on the red planet.

And I'm pretty sure we will find it within the next 50 years

It's plausible that the aliens if they did/have communicated have done so in a medium we do not use/cannot pick up as of yet. I'd say the prospect of bacteria appearing on other planets is far more likely/probably.

I think the poll results reflect common sense, micro organisms just seems so much more likely! Of course we have absolutely no idea, only theories, and anyone who says otherwise is not being intellectually honest. But as for theories, I think it's the much more plausible / likely of the two.

I saw something somewhere making the case that multicellular life is unique to earth, and that it happened by accident, and they made the case that any alien life would be single celled and bacteria like.
It was a video by Kurzgesagt on youtube I believe.

john_chandler wrote:

 Jadenim wrote:

I’d been thinking that too recently; high power wide area transmissions are too inefficient and inflexible. Given the current trends on streaming, fibre broadband and low power 5G, it’s highly likely that in 20 years we will have abandoned traditional TV and radio transmissions, which are the big culprits for off-world detection. If you assume that other technological civilisations would follow the same arc, the you only have a window of ~150 years in which to detect them. The chances of other intelligent life existing at the same time as us are fairly low. The chances of them being at the exact same point in technological development and within detection range with such a narrow time window is vanishingly small, unfortunately. I think SETI need to start looking at ways to detect non-transmitting technological civilisations, as that’s much more likely; spectroscopic analysis of exoplanet atmospheres perhaps?

SETI has projects looking at other signatures of intelligent life, not just radio waves. The idea of using lasers to send a message has been around for decades, and there have been some attempts to try and spot these over the years..

Lasers are short range and directed. They'd be much harder to spot than radio waves.

Consider the history of life on Earth, and how much of it was spent as microbes. Compare to how much has been spent spitting out interstellar communications.

Voss wrote:

john_chandler wrote:

SETI has projects looking at other signatures of intelligent life, not just radio waves. The idea of using lasers to send a message has been around for decades, and there have been some attempts to try and spot these over the years..

Lasers are short range and directed. They'd be much harder to spot than radio waves.

Directed, yes. Short range, not necessarily. Lasers give you more "bang for your buck" energy-wise than radio transmissions, but for sure you have to be more precise - you can't realistically broadcast everywhere. Yes, it's fair to say that lasers would be affected by dust and gas, unlike radio waves, but on the other hand they are less susceptible to other forms of interference/degradation.

SETI is already searching for millisecond duration pulses from lasers not much different in power to those we operate ourselves. We already have lasers that could create a pulse seen from another star system that would be thousands of times brighter than our sun.

Microbes seem most likely to me (although if they're DNA based it's going to be really hard to 'prove' they came from space rather than being a rare contaminant on the equipment sent to find them)

I fear that other intelligent races with technology advanced enough to detect by current methods will exist for too short a time before vanishing either as they eliminate themselves or move on to using more environmentally friendly tech that doesn't involve messing up their atmosphere or broadcasting EM radiation out to the whole universe

and if there is an intelligence capable enough to travel to meet us in a sensible time frame I suspect they would either keep well away from an 'primitive' civilisation like ours or be looking to exploit us in the same way that more advanced civilizations on earth have exploited the less advanced ones.

Misclicking ork wrote:
I saw something somewhere making the case that multicellular life is unique to earth, and that it happened by accident, and they made the case that any alien life would be single celled and bacteria like.
It was a video by Kurzgesagt on youtube I believe.

This is why the current Mars and (hopefully Europa) missions are so important; from the history of our planet we know that a) life appeared almost as soon as conditions on the planet were suitable and b) it then stagnated for a loooong time, before some freak event precipitated multicellular life. Now, given the size of the universe, or even just our galaxy, I don’t believe multicellular life is going to be unique to Earth, but it will probably be rare compared to single cell life. If we find evidence of independent life on Mars and Europa (both would be great), then it would back up point a) that life is actually really easy to get started, which means single-called life would probably present pretty much anywhere with vaguely habitable conditions (I.e. all over the place). This would then mean that there is a far greater chance of other multicellular “accidents” happening, probably giving an appreciable number of multicellular biomes and the consequent potential for the development of intelligent life.

Of course, if we don’t find any signs of life then genesis on Earth was probably a fluke and the universe is going to be very sparsely populated indeed. Probably the worst result would be to find Terran-linked life, as that wouldn’t really tell us as much, other than some microbes are real hard bastards and can survive being blasted around the solar system on rocks (which we sort of know already).

This is also why I’m a big supporter of space exploration (including human space flight); if life is easy then there’s a whole galaxy of wonders out there to explore. If life is hard, then we may well be unique and we have a duty to preserve this miracle from random chunks of space rock, gamma ray bursts, etc. Either way, we need to get out there.

alien species, but will probably contact using super nuke, or earth destroying ray gun, will probably need will Smith and the Goldblum to save us.

Deinately be interesting to see it happening but for the most part life does nto seem to be that interesting.

Tinfoil hat time -

I think the worst-case scenario is they bring some sort of microbe/fungus from mars and it just ends up destroying earths ecology if nothing exists that stops it from feeding/changing.

Not saying there will be some sort of rapidly evolving life form like the film. But some sort of ancient fungus that once hits atmosphere and nutrient rich earth? Fungi are scary...

 Argive wrote:
Tinfoil hat time -

I think the worst-case scenario is they bring some sort of microbe/fungus from mars and it just ends up destroying earths ecology if nothing exists that stops it from feeding/changing.

Not saying there will be some sort of rapidly evolving life form like the film. But some sort of ancient fungus that once hits atmosphere and nutrient rich earth? Fungi are scary...

If we did bring a space fungus back to Earth from Mars it would probably get destroyed by our native organisms. On Mars it wouldn't have much in the way of biological competition, bringing it to Earth would be like dropping a sheep into a pit of wolves.

Grey Templar that is the best case scenario for us. Most Earth organisms tend to be kept in check by specific predators. Once they hit an area without the predator in question, they devastate ecosystems.

If we really find a fungus that grew millennia ago, and survived Mars' ecosystem's collapse then it's going to be one tough customer.

Voss wrote:


As far as we know, faster than light is non-viable, so any 'space-faring' civilizations are going to operate in very localized clusters. The odds that one (or even a post industrial one) is near us is pretty poor.

Well getting near(and l mean damn near) lightspeed would be enough to set up independent human colonies basically everywhere in lifetime of pilots. Of course tricky part is getting ships near lightspeed

 Argive wrote:
Tinfoil hat time -

I think the worst-case scenario is they bring some sort of microbe/fungus from mars and it just ends up destroying earths ecology if nothing exists that stops it from feeding/changing.

Not saying there will be some sort of rapidly evolving life form like the film. But some sort of ancient fungus that once hits atmosphere and nutrient rich earth? Fungi are scary...

Fortunately this is not something that will actually occur. In the sense that yes, it -could- happen, but I -could- be struck dead by a meteorite when I step outside my house today. The reality is that the adaptations to survive a Martian ecosystem would render this theoretical organism somewhat like a fully-suited astronaut. On Mars, the astronaut beats any other human, because we can't survive. But on Earth that suit is ridiculously bulky, cumbersome, and inefficient, rendering the astronaut at a massive disadvantage to the locals.

Invasive species happen when the organism is adapted to a similar environment then jumps to a new one while leaving its predators behind. An organism jumping from Mars would only pose an invasive threat to ecosystems which are similar, so those of us outside Australia are OK.

I also voted for "alien micro-organisms" because it seems much more probable than the development of interstellar communication in our range to me, although I would not expect to necessarily find life in a form we know from our own planet. There are numerous possibilties within the given limits of physics and chemistry how biology could work, cells we know from mircobes and multicellular organisms are not even needed, neither is DNA, since there are countless possibilities how information could be stored and reproduced. If it's simple life we encounter I am also rather confident it might try to eat us, because we are such a nice accumulation of energy rich molecules and plenty of useful elements. I am also confident we might try to eat them.

“Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.”

― Arthur C. Clarke

I expect some rock thrown at us from out-of-nowhere that will cause an extinction level event. We will never even know that it WAS extra-terrestrials sending us a very final message.

Oddly, this was not one of the poll options?