Evidence for ET is mounting daily, but not proven.

[Swift]

Religion doesn't matter. It won't stop the progress of science either.

This not just aimed at CaptainToonces, but everyone.

Everyone chill.

First, please, let's not draw religion into this discussion, either pro or con.

Second, I have not followed this thread recently, nor am I going to review 150 posts, but what are you all talking about? What does WWII and the progress of science during the Dark Ages have to do with "Evidence for ET is mounting daily"? This thread seems to be passing from derailment to train wreck. Stick to the topic or take the debate elsewhere.

[CaptainToonces]

What WWII to has to do with evidence of ET is related to the drake equation factor of "what is the longevity of an intelligent civilization"

And to address IsaacKuo: You make some good arguements about intelligent life possibly being out there just not being interested in coming to our Solar System, but the main point remains there is zero evidence even as our abilities to detect such evidence becomes stronger (due to paleontology and geo-history as much as anything else).

To address the OP, there is a mounting level of NON-evidence for ET out there.

[IsaacKuo]

As I said, what we have is an awesome lack of evidence either way.

And we just don't know if there are probes crashing around or lighthouses out there. Alien probes could be criss crossing our Solar System and we really wouldn't know it--even if we were lucky enough to spot one it would look much like any other small object. If some alien probes have crashed into Earth, we would be quite lucky to find any.

As for lighthouses--it's certainly plausible for aliens to use something similar to GPS for navigation, but there's no reason to expect those signals to be visible across interstellar distances. Would you expect to see any lighthouses in the middle of the Pacific Ocean? No, of course not! They're only used to help local navigation, so there's no need for them to be visible across an ocean. And it's not like there's any shortage of natural "lighthouses" throughout the galaxy for navigation in deep space.

[A.DIM]

To address the OP, there is a mounting level of NON-evidence for ET out there.

25yrs ago there were no known exoplanets. Too many to name now. And in that time it was thought Mars, Venus, Europa, Titan (to name a few) were entirely uninhabitable. Not so now. Also, life as we knew it couldn't survive myriad extreme conditions on Earth, and in space. Extremophiles have proven otherwise. Plentiful organics, complex molecules, increased estimates of numbers of stars etc. can also be thrown in with the mounting evidence suggestive ET life exists.

The search for intelligent ET entails little more than listening for the last 50yrs, which IMO borders on the absurd in chance of discovery and has done next to nothing in advancing knowledge.

[baric]

25yrs ago there were no known exoplanets. Too many to name now. And in that time it was thought Mars, Venus, Europa, Titan (to name a few) were entirely uninhabitable. Not so now. Also, life as we knew it couldn't survive myriad extreme conditions on Earth, and in space. Extremophiles have proven otherwise. Plentiful organics, complex molecules, increased estimates of numbers of stars etc. can also be thrown in with the mounting evidence suggestive ET life exists.

The search for intelligent ET entails little more than listening for the last 50yrs, which IMO borders on the absurd in chance of discovery and has done next to nothing in advancing knowledge.

I gotta agree with A. DIM on this one. The known set of possibilities for life is far, far greater than it was just 20 years ago. An increased sample size in which life can thrive can only increase the odds for it to develop. That has to count for something.

[KABOOM]

For those that feel that "technology" will eventually lead homo sapiens to interstellar travel, please address the resource issue.

The Earth has 7 billion people, growing to a steady state level of ~ 9 billion (per Natl Geographic).

There are HUGE challenges facing the more advanced societies of our present planet.

- Resource depletion.
- Water/food shortages.
- A need for a migration to renewable (solar) energy
- Increased levels of defense expenditures
- Climate changes that could compound water/food shortages.

The trend has been to spend a smaller portion of the pie on interstellar travel. Given that the problems of the next 100 years will be huge and require a priortization of our resources I don't see interstellar travel ever being a priority for Earthlings. Domestic challenges, by definition more immediate, will always trump the focus and will that will be required to make interstellar travel a reality

[IsaacKuo]

For those that feel that "technology" will eventually lead homo sapiens to interstellar travel, please address the resource issue.
[...]
- Resource depletion.

Which resources, specifically, are relevant? The Earth has an extremely small fraction of the Solar System's resources. Those of us who realistically expect interstellar travel to be a part of our future don't seriously expect this to happen before we first master interplanetary travel. Interplanetary travel is many orders of magnitude less challenging.

- Water/food shortages.

Why would this have anything to do with interstellar travel?

- A need for a migration to renewable (solar) energy

This will happen within the next few centuries, sure. Interstellar travel will take longer to accomplish.

- Increased levels of defense expenditures

If anything defense spending will bring about interstellar travel slightly sooner. Weapons lasers technology may be suitable for eventual upscaling for interstellar propulsion systems.

- Climate changes that could compound water/food shortages.

Again, what does this have to do with interstellar travel?

The trend has been to spend a smaller portion of the pie on interstellar travel.

No, the trend has been to spend a constant portion of the pie on interstellar travel--namely, zero percent. It just isn't technologically feasible yet.

We have some of the technologies necessary, but humanity's energy budget will need to expand by several orders of magnitude before we can afford the awesome energy requirements for a manned interstellar mission. That means significant exploitation of resources beyond Earth's atmosphere (at the very least, extensive space based solar power satellites).

Given that the problems of the next 100 years will be huge and require a priortization of our resources I don't see interstellar travel ever being a priority for Earthlings. Domestic challenges, by definition more immediate, will always trump the focus and will that will be required to make interstellar travel a reality

The things that will make interstellar travel a reality won't be useful for interstellar travel alone. They will be useful for domestic reasons. For example, future beamed power systems may be useful for green suborbital spaceliners.

[astromark]

Remembering the OP and considering all the ground we have covered here... does at a minimum show what a diverse subject this is...

Evidence of ET is NOT mounting... Our abilities to detect and find environments that might support life of some sort has leapt forward...

We have 0 case study of off planet earth life forms... I would not make the fools assumption it will not be found.

but, finding it is still in our future... Technical ability has not yet confirmed the expected. How would you suggest a political will be built. ?

[Moose]

Agreed. We're learning about how to search for ET (but for all our leaps and bounds in that field, we're still very much in our infancy). There is, other than the existence of life on our planet, precisely zero evidence pointing to ET. Oh, we have increasing reason to believe there's going to be something out there, but that is not evidence. It's plausibility. Plausibility isn't nothing, but it's not evidence.

[A.DIM]

It seems a matter of perspective what is considered "evidence" here, or perhaps an unwillingness to call it what it is.
I've heard everything from "better equipement ... clues of life not invisible" to "increasing reason to believe" to "all our leaps and bounds" and yet none of it is considered evidence, circumstantial even.

Our leaps and bounds, increasing reasons to believe and clues of life are based on observation, experiment and discovery.
I disagree these observations, experiments and discoveries do not amount to evidence.
IMO, evidence mounts, circumstantial yes, but evidence no doubt - suggestive of ET life.
Call 'em "plausibilities" if you must.

[Paul Beardsley]

What I would call "circumstantial evidence" would be observations of phenomena that are not necessarily indicative of life but could well be, especially if seen in combination with other suggestive phenomena. The gas experiments on Viking would count here.

More solid evidence would include footprints in the Martian soil (or regolith), or unstable chemicals in an atmosphere such as oxygen.

If any of these are listed in this thread (or indeed the news generally) and I've missed them (which is highly possible) then I'd be delighted to hear about them.

But data about life's ability to thrive in a broader range of environments than we previously thought... is all very interesting but is so obviously not evidence of ET life.

Also, given that the evidence is "mounting daily", I'd really like to know what evidence there was one day before this thread began which was not there two days before.

[Hlafordlaes]

Also, given that the evidence is "mounting daily", I'd really like to know what evidence there was one day before this thread began which was not there two days before.

I was waiting to see who'd go for the low-hanging fruit. Nice one.

Intelligent ET life is an increasingly plausible hypothesis that meets all my deductive criteria, yet remains theory awaiting experimental confirmation.

[KABOOM]

Which resources, specifically, are relevant? The Earth has an extremely small fraction of the Solar System's resources. Those of us who realistically expect interstellar travel to be a part of our future don't seriously expect this to happen before we first master interplanetary travel. Interplanetary travel is many orders of magnitude less challenging.

Why would this have anything to do with interstellar travel?

This will happen within the next few centuries, sure. Interstellar travel will take longer to accomplish.

If anything defense spending will bring about interstellar travel slightly sooner. Weapons lasers technology may be suitable for eventual upscaling for interstellar propulsion systems.

Again, what does this have to do with interstellar travel?

No, the trend has been to spend a constant portion of the pie on interstellar travel--namely, zero percent. It just isn't technologically feasible yet.

We have some of the technologies necessary, but humanity's energy budget will need to expand by several orders of magnitude before we can afford the awesome energy requirements for a manned interstellar mission. That means significant exploitation of resources beyond Earth's atmosphere (at the very least, extensive space based solar power satellites).

The things that will make interstellar travel a reality won't be useful for interstellar travel alone. They will be useful for domestic reasons. For example, future beamed power systems may be useful for green suborbital spaceliners.

My point on resources can be boiled to financial resources and energy resources.

On the financial front, despite World GDP at a record level (even if measured in constant dollars) we can not muster a big enough piece of the pie to even attempt a manned visit to Mars (or even a return engagment to the moon). Interstellar travel would require orders of magnitude more financial resources. Given all of the competing needs on Earth I see no "evidence" that mankind will ever get close to choosing to allocate the requisite financial resources.

Energy. On this front one needs to assume that man will be able to almost "limitlessly" harness the solar power of our sun. We are so far away from this that is pure speculation.

[Hawk xSx]

Is possible we have MISSED radio signals or some type of communication due to our lack of technology to capture and convert it?

[Trakar]

Is possible we have MISSED radio signals or some type of communication due to our lack of technology to capture and convert it?

Welcome!
Yes, I would expect that, technology rarely stays unchanged for centuries, from our own experience, but there are some base technological processes (warning/navigation beacons, active microwave detection systems, etc.,.) which may well persist across spans of much longer times. The problem is in looking for these potential common byproducts of a space-faring technological species, and being able to scan for them in high enough definition to pick them up across interstellar distances.

[ravens_cry]

Is possible we have MISSED radio signals or some type of communication due to our lack of technology to capture and convert it?

Welcome to BAUT!
Let's see, we have had radio in any form for a bit over hundred years, the Universe is billions of years old, carry the two. By my pie in the sky calculations and bum pull numbers, I would indeed say that if, if mind, there has been communications directed at your planet, it is overwhelmingly likely to have already reached us before we developed the ability to detect it.

[A.DIM]

Welcome to BAUT!
Let's see, we have had radio in any form for a bit over hundred years, the Universe is billions of years old, carry the two. By my pie in the sky calculations and bum pull numbers, I would indeed say that if, if mind, there has been communications directed at your planet, it is overwhelmingly likely to have already reached us before we developed the ability to detect it.

Going further, here we are a hundred years later crowding more and more into the usable bandwidths, necessitating lower wattages ... we're effectively becoming invisible ourselves. Whatever signals escape from Earth would be rather quickly garbled by background radiation; likewise for any signals SETI hopes to find. That is, unless the goal is to discover ETi only as advanced as that on Earth a hundred years ago. Yet another reason I consider SETI, in its current form, as bordering on the absurd.

And welcome to BAUT Hawk xSx!

[A.DIM]

I wanted also to say that I think our search for ET should be guided by the evidence. There is more evidence suggesting extremophile ETs could exist in our own solar system than there is for radio leaking ETs from afar. Our efforts should be intensely focused on rovers designed specifically to search for such ET life.

[baric]

Going further, here we are a hundred years later crowding more and more into the usable bandwidths, necessitating lower wattages ... we're effectively becoming invisible ourselves. Whatever signals escape from Earth would be rather quickly garbled by background radiation; likewise for any signals SETI hopes to find. That is, unless the goal is to discover ETi only as advanced as that on Earth a hundred years ago. Yet another reason I consider SETI, in its current form, as bordering on the absurd.

Do you think it's possible that advanced ET life may be trying to be detected and, if so, those are the signals we will detect?

[Sauna]

I have to agree with A DIM. I have run the numbers on the energy that would radiate from our world, and it would be very hard to detect beyond the closest stars. Essentially ET would have to be deliberately broadcasting to us which uses their resources and energy. Remember that stars are separated by light years so it would take a very long effort of broadcasting high powers to achieve this. Most likely ET would select the best candidates closest to them and broadcast to them exclusively, which has been mentioned in this thread earlier.

Even our own transmissions use specialized modulation strategies that can only be pulled out of the background noise by knowing the modulation strategy used. There is a fundamental physical limit on this noise too. How long did it take us to start using these methods? Only 100 light years. Accidental detection from world leakage is very far fetched in my opinion. Most likely as we continue to improve our exoplanet detection methods we will be able to target more specific areas. Basically it comes down to the drunk man looking for his keys under the street light even though he never walked there before - soon we will be able to look only where we need to.

[Sauna]

I have to agree with A DIM. I have run the numbers on the energy that would radiate from our world, and it would be very hard to detect beyond the closest stars. Essentially ET would have to be deliberately broadcasting to us which uses their resources and energy. Remember that stars are separated by light years so it would take a very long effort of broadcasting high powers to achieve this. Most likely ET would select the best candidates closest to them and broadcast to them exclusively, which has been mentioned in this thread earlier.

Even our own transmissions use specialized modulation strategies that can only be pulled out of the background noise by knowing the modulation strategy used. There is a fundamental physical limit on this noise too. How long did it take us to start using these methods? Only 100 years. Accidental detection from world leakage is very far fetched in my opinion. Most likely as we continue to improve our exoplanet detection methods we will be able to target more specific areas. Basically it comes down to the drunk man looking for his keys under the street light even though he never walked there before - soon we will be able to look only where we need to.

[A.DIM]

Do you think it's possible that advanced ET life may be trying to be detected and, if so, those are the signals we will detect?

I suppose it's possible but what kind of signals are you thinking?
I usually think that if we're to know advanced ET it will be on their terms, not by some radio or laser signals, or astroengineering projects we might happen upon.

[baric]

I suppose it's possible but what kind of signals are you thinking?
I usually think that if we're to know advanced ET it will be on their terms, not by some radio or laser signals, or astroengineering projects we might happen upon.

I agree with that completely. We need to focus on looking for signals that are intended for us to find, not trying to stumble across random "I Love Gort" episodes.

So, hypothetically, if you were an advanced ET civilization and wanted to let others know of your presence --- exactly how would you do that (assuming interstellar travel is impossible or impractical)?

For starters, you would search exosystems for planets that show the capability for life... this is something that even we are just beginning.

Then you would want to target your signals to those systems with characteristics that would be most easily identifiable... i.e. a clearly non-natural signal broadcast at wavelengths that would not be blocked by their atmospheres.

Finally, because of power requirements, you would expect signals to be very short bursts fired periodically... like beacons. At the same time, you would monitor systems for beacons of their own.

So, imo, we should look for beacons on wavelengths that can be detected at ground level. And what are those? Radio signals.

What we need to do is increase our search coverage in both the sky and the radio bandwidth, and then improve our ability to find short signals.

I don't think SETI's approach is irrational or misguided... just still very limited by technological constraints.

[transreality]

Seti, at least, is a scientifically rigorous attempt to gather real evidence within an experimental framework that is testing particular ET hypotheses. At least we can surmise, we are unlikely to be surrounded by a busy advanced interstellar society that is keeping us in a reserve until we demonstrate an ability to transcend our own savagery. We also have evidence that ancient martian civilisations are unlikely to have ever existed. Theories that suggest significant quantities of biological material floating free in space have also be been tested and remain unsupported by missions that sample the interplanetary medium. It is not for lack of looking, or even the testing of more lurid theories, that no evidence has been forthcoming.

[A.DIM]

I agree with that completely. We need to focus on looking for signals that are intended for us to find, not trying to stumble across random "I Love Gort" episodes.

OK, so we're to assume some hypothetical advanced ET civ wants to be found in order to justify SETI in its current(and projected future) form?

So, hypothetically, if you were an advanced ET civilization and wanted to let others know of your presence --- exactly how would you do that (assuming interstellar travel is impossible or impractical)?

For starters, you would search exosystems for planets that show the capability for life... this is something that even we are just beginning.

Then you would want to target your signals to those systems with characteristics that would be most easily identifiable... i.e. a clearly non-natural signal broadcast at wavelengths that would not be blocked by their atmospheres.

Finally, because of power requirements, you would expect signals to be very short bursts fired periodically... like beacons. At the same time, you would monitor systems for beacons of their own.

So, imo, we should look for beacons on wavelengths that can be detected at ground level. And what are those? Radio signals.

What we need to do is increase our search coverage in both the sky and the radio bandwidth, and then improve our ability to find short signals.

I don't think SETI's approach is irrational or misguided... just still very limited by technological constraints.

It's a fair scenario baric, (albeit based on the assumptions that advanced ET civs can't travel interstellar distances and want to be found) but again, in its current form the SETI borders on the absurd in chance of discovering anything. I'd love to be proven wrong, I assure you.

[A.DIM]

Seti, at least, is a scientifically rigorous attempt to gather real evidence within an experimental framework that is testing particular ET hypotheses.

SETI Institute uses the Drake Equation as some basis for their research.
The Phoenix project was rather rigorous but do you think its null results were comprehensive?
To what other particular ET hypotheses are you referring?

At least we can surmise, we are unlikely to be surrounded by a busy advanced interstellar society that is keeping us in a reserve until we demonstrate an ability to transcend our own savagery.

How can we surmise this? If such a "zoo hypothesis" were correct how would we know? Any advanced interstellar civ would be like magic to us, no? What might we expect then as evidence if we're in such a "zoo?" UAP, UFOs and stories of visitors from the heavens perhaps?

We also have evidence that ancient martian civilisations are unlikely to have ever existed.

Yes, it appears more likely Mars is inhabited by extremophile life, and if so it's likely already related to Earth life.

Theories that suggest significant quantities of biological material floating free in space have also be been tested and remain unsupported by missions that sample the interplanetary medium. It is not for lack of looking, or even the testing of more lurid theories, that no evidence has been forthcoming.

No, extremophiles aren't found floating free in the interplanetary environment but we have evidence some can survive up to 6yrs naked in space; More research like this has better chance of discovery. There is evidence supporting ballistic panspermia as well. It is now known life could survive the impact and ejection parts of the process, and if sufficiently shielded could survive the travel times between say Mars and Earth. We also find life in various Earth analogs of environments elsewhere in the solar system.
Thus, IMO, there's more evidence which suggests our efforts should focus on extremophile life in the nearby environments than there is for advanced ET civs wanting to intentionally reveal themselves via laser beacons.

[baric]

OK, so we're to assume some hypothetical advanced ET civ wants to be found in order to justify SETI in its current(and projected future) form?

Yes. As you've suggested earlier, I think it's likely that civilizations rapidly "go dark" fairly quickly, making it unreasonable to hope for finding stray broadcasts.

It's a fair scenario baric, (albeit based on the assumptions that advanced ET civs can't travel interstellar distances and want to be found) but again, in its current form the SETI borders on the absurd in chance of discovering anything. I'd love to be proven wrong, I assure you.

I think that, given the current state of scientific knowledge, it is very reasonable to assume that interstellar communications are more energy-efficient when done remotely, rather than via personal contact. Also, let's not forget that one solution to the Fermi Paradox is that interstellar travel is either impossible or impractical.

SETI is taking the proper approach, imo, although I agree that their chances of finding a signal with current technological restrictions are extremely remote. However, let's not forget two important things:

1) "extremely remote" is > 0
2) SETI is privately funded

There are also advantages to having the infrastructure and expertise in place so that SETI is well-positioned to immediately take advantage of improvements in technology.

[transreality]

No, extremophiles aren't found floating free in the interplanetary environment but we have evidence some can survive up to 6yrs naked in space; More research like this has better chance of discovery. There is evidence supporting ballistic panspermia as well. It is now known life could survive the impact and ejection parts of the process, and if sufficiently shielded could survive the travel times between say Mars and Earth. We also find life in various Earth analogs of environments elsewhere in the solar system.
Thus, IMO, there's more evidence which suggests our efforts should focus on extremophile life in the nearby environments than there is for advanced ET civs wanting to intentionally reveal themselves via laser beacons.

The fastest earth to mars bolide we have evidence for took 115,000 years. It could turn out that the interplanetary quarantine imposed by space could be absolute, this is worthy of testing. I think the most likely source of evidence for ETL will be from environments detected around extra solar planets, if only because of the promise of so many samples.

[Trakar]

Yes. As you've suggested earlier, I think it's likely that civilizations rapidly "go dark" fairly quickly, making it unreasonable to hope for finding stray broadcasts.

Well, I don't think communications broadcasts generally ever approach anything detectable across interstellar distances. Radar and guidance/navigation systems, should increase in detectability as a technological species expands, first across its planet and then even more so as it expands out into its stellar system. Sure the technologies improve and there is a more efficient application of energy, but the speeds and distances involved in an aggressively expanding civilization trying to map and survey explore their system, and as the effort progresses and extended supply and passenger chains are established, it is easy to see how they might develop a growing glow in some frequencies. Of course this is a projection/speculation, as we haven't reached that stage ourselves yet (or at least are just on the leading brink of), so I don't know what hasn't happened yet,...I'm just saying that there is a reasonable argument that technological civilizations don't necessarily become more invisible due to technological innovation and advance.

[Trakar]

The fastest earth to mars bolide we have evidence for took 115,000 years. It could turn out that the interplanetary quarantine imposed by space could be absolute, this is worthy of testing. I think the most likely source of evidence for ETL will be from environments detected around extra solar planets, if only because of the promise of so many samples.

I don't find the potential for IP cross-polination to be prohibitive; in fact, I'm of the mind that even most simple life is probably much more rare an occurence than a typical and expected outcome for conditions tolerant for, and even conducive to, life to arise (whatever those precise conditions/limits are). It is the step beyond IP to IS that I find generally more implausible, without significantly more abundant evidences than are apparent.