A theory on why we probably haven't received signals from aliens

[UnionPacific1983WP]

You know how there are still some "uncontacted tribes" in various places on Earth? Maybe other civilizations in the galaxy are treating us relatively the same as those "uncontacted tribes", for whatever reason, purposely not sending us a signal.

But that's just a theory... a space theory! (10 points if you get the reference)

What do you think?

(This thread was inspired by this video:

) Edited September 2, 2015 by UnionPacific1983WP

[Spacetraindriver]

I think they just have no benefit meeting us. Or are AFRAID of us. Or are just too plain lazy to contact us.

[Budgie]

But how do you stop mass-broadcasted signals from not getting to us? I know nothing about communications and such, but I doubt you can avoid broadcasting out into space and yet also avoid sending messages/noise to one specific area of the galaxy.

[SargeRho]

But how do you stop mass-broadcasted signals from not getting to us? I know nothing about communications and such, but I doubt you can avoid broadcasting out into space and yet also avoid sending messages/noise to one specific area of the galaxy.

After a few lightyears, they're indistinguishable from the CMBR. Something like a search radar might get to us though. Our own TV broadcasts don't get much further than 2-3 lightyears.

[Vaporo]

Possible. We could be being treated as some kind of "nature reserve."

But it's more likely that there's either nobody (nearby, at least) signaling at the moment, that the transmissions are so faint that we just can't hear them, or a dozen other possibilities. The "nature reserve" option is probably the least likely, IMO.

EDIT:

But how do you stop mass-broadcasted signals from not getting to us? I know nothing about communications and such, but I doubt you can avoid broadcasting out into space and yet also avoid sending messages/noise to one specific area of the galaxy.

If our own technology is any indication, broadcast signals only exist for a short time before being largely eliminated by more efficient things like fiber optics. As for interstellar communication, it's probably much more efficient to focus a "laser" communication as opposed to wasting energy screaming into the void in all directions.

Edited September 2, 2015 by Vaporo

[Bill Phil]

But how do you stop mass-broadcasted signals from not getting to us? I know nothing about communications and such, but I doubt you can avoid broadcasting out into space and yet also avoid sending messages/noise to one specific area of the galaxy.

Maybe they use laser communication, or something like that.

Energy is decreased as the distance increases. Eventually what we broadcast would be indecipherable. Same with aliens... IF they use EM comms.

[GeneralVeers]

Most likely explanation: they simply haven't found us.

One particular YouTube personality (and KSP player!), Kurtjmac, recently raised this theory: that human beings have only been emitting radio and television signals for a century or so. That means that a technologically-advanced civilization would have to be (or their ships would have to fly) within one-hundred light-years of Earth to even spot us. That's a pretty tiny needle in a colossally gigantic haystack.

On further reflection, I think I can safely throw this in: for aliens to contact us based on the above, is assuming those aliens are searching for RADIO signals. Why would they? There's no reason to assume they would even invent radio, therefore no reason to assume they would even know about radio. Throw in the fact that pretty much the entire planet Earth is switching to digital and cell transmission in an entirely different frequency range, and the problem of spotting Earth becomes even more complicated.

But, of course, Occam's Razor. The question of why aliens haven't contacted us can be answered very elegantly, by simply flipping it around and asking: "hey, humans, why haven't YOU made contact with ALIENS???"

[vger]

Here's why.

[problemecium]

Here's an idea:

One day, barring another Dark Ages, annihilation in World War III, etc., we ourselves will be a space-faring society. In order to communicate over astronomical distances, we're likely to develop something based on wormholes, entanglement, etc. (Yes I do know why entanglement doesn't already work. But the basic idea at least.) - because light-based signals would be like snail mail. If I want a live feed from Jupiter, radio signals won't work, let alone a live feed from Proxima Centauri.

We don't currently have this technology, so we have no way to pick up the kinds of signals our future selves will be using. If the extraterrestrials dropped by (as in landed on our Moon or something), we might be able to pick up their walkie-talkies, but their long-range stuff may well be passing us by completely undetected.

Say they use a system where they build a small wormhole, put one end on a ship and the other at their base, and run a wire through it. Effectively, the distance to the ship through the wormhole is only a few yards at most, even if outside it's light-years. Thus it'd be easy to communicate with a distant spacecraft with negligible delay - and as a completely unintended side effect, the signal doesn't go dispersing all over space. Since the signal is inside the wormhole - inside the wire in fact - no amount of radio telescopy is going to reveal it out here, and it's not because anyone put any effort into hiding it.

On a related note, imagine in the far future we want to land a rover on an exoplanet, but we suspect that planet has something living on it. Even today, we make painstaking effort to sterilize our rovers and not harm the Martian environment more than is necessary to land the thing (it's solar powered rather than gas powered, to put it bluntly). Mars isn't even inhabited, except mayyybe by a few microbes. If we knew there were a good chance of something like, say, a coral reef or a rainforest (equivalent - we obviously won't find a literal rainforest), we'd be all the more careful, to the point where, ideally, they'd never know we were there.

So if we turn it around, if anything's been probing Earth, even if they're the careless, warlike sort of people we are, their scientists are entirely liable to have sent something so stealthy we'd never notice. The probability is small, of course (in fact my bet is it hasn't actually happened), but it's entirely plausible.

[Scotius]

Maybe they do not believe in aliens - and thus do not search for any contact. Or maybe we were at Bronze Age when they searched our area of space. Ot maybe our closest neighbours are at Bronze Age, unable to receive our signals and send their own for us to receive. Possibilities are endless.

[PB666]

Given the distribution of planet masses, the goldilocks zone is much thinner and highly dependent on planet mass. Therefore planets with sentient life on it are so far from us that we cannot listen to them the with our currently available technology.

They might be able to hear us, but not for a few hundred years, which is good because it means we have at least 1000 years before they reach earth and try to destroy us. :^)

[Rakaydos]

Given the distribution of planet masses, the goldilocks zone is much thinner and highly dependent on planet mass. Therefore planets with sentient life on it are so far from us that we cannot listen to them the with our currently available technology.

They might be able to hear us, but not for a few hundred years, which is good because it means we have at least 1000 years before they reach earth and try to destroy us. :^)

Also, the planets with conditions that give them wider habitable zones also have conditions tha SUCK for launching spacecraft. Larger worlds, denser atmospheres.

In order to conquer the galaxy, first they must colonize their mars equivalent. See other threads on how hard that is, then make getting even to the ISS twice as expensive.

[problemecium]

Goldilocks zone, schmoldilocks zone. There might well be creatures on Pluto that think the other planets are way too hot for life, since they can't sustain liquid helium on their surfaces or some such.

Until we actually find some extraterrestrials, we shouldn't go around assuming they'll have the exact same needs as we do - we, who evolved on this planet and in so doing tailored our needs to match what was available.

Keep in mind, when life first appeared on Earth, oxygen was a toxic waste product. They would consider today's atmosphere hellish, our Sun too bright, the tides too weak, etc. etc.

[ChrisSpace]

But that's just a theory... a space theory! (10 points if you get the reference)

I get the reference! Now can I have 10 points?

[magnemoe]

You know how there are still some "uncontacted tribes" in various places on Earth? Maybe other civilizations in the galaxy are treating us relatively the same as those "uncontacted tribes", for whatever reason, purposely not sending us a signal.

But that's just a theory... a space theory! (10 points if you get the reference)

What do you think?

(This thread was inspired by this video:

)

it makes some sense for one reason: we are in the short time period between industrialization and been capable of traveling between stars or some other breakthrough like singularity.

This is an very short time period on an cosmic scale and we are probably the only civilization at this stage and well worth of study, now if aliens contacted us this will change history, so any contact even message will ruin the study (and void any bets )

Contacting an prehistoric culture would not have any impact outside of stuff you taught them. Even an preindustrial one would have limited impact.

No I don't think this is likely, more probably that distances are too long, also that aliens don't use high power radio.

[Dodgey]

Hypothesis, say it with me. Hypothesis.

On topic one thing that nobody ever seems to consider is that maybe we are the advanced ones, assuming that other life manages to evolve intelligences without killing themselves off with the power of the atom.

[PB666]

Hypothesis, say it with me. Hypothesis.

On topic one thing that nobody ever seems to consider is that maybe we are the advanced ones, assuming that other life manages to evolve intelligences without killing themselves off with the power of the atom.

Yet. Nuclear technology has not trickled through every despotic regime yet. Although personally the atomic threat has been overplayed, ISIS is not worried about the nuclear threat, but if they could play that threat on others I'msure they would. The biggest fear should be luddites, remember the unibomber, use technology to destroy all technology and there enforcing ones lifestyle on others. If you respect the technology you are less likely to use it in a way that brings disrespect. I think that is a critical reason why Truman took the bombs control from the Army. There are some technologies that simply work better in a threat/respect posture. I don't think this would assess differently in other cultures-worlds, but it is somewhat fortunate that the anti-autocratic anti-classic emperialism US got the weapon before the Fascist in Europe did.

[ComradeWolfe]

Goldilocks zone, schmoldilocks zone. There might well be creatures on Pluto that think the other planets are way too hot for life, since they can't sustain liquid helium on their surfaces or some such.

Until we actually find some extraterrestrials, we shouldn't go around assuming they'll have the exact same needs as we do - we, who evolved on this planet and in so doing tailored our needs to match what was available.

Keep in mind, when life first appeared on Earth, oxygen was a toxic waste product. They would consider today's atmosphere hellish, our Sun too bright, the tides too weak, etc. etc.

While this is somewhat true, I do think that you underestimate the logic behind scientists' assumptions.

"Life" is a series of chemical reactions. The thing to remember is that these reactions have to produce something that is self-replicating. The problem is that at low temperatures, these reactions generally don't occur -- atoms happily sit around with other atoms in stable molecules, never bothering to move around and find new buddies for new molecules (which means no self-replication and no life). When temperatures get too hot, the molecules tend to break down in to smaller molecules which are too stable to react with anything else (again, no self-replication and no life). The key thing is finding a temperature range where you can have a big enough variety of molecules to form self-replicating structures and reactions.

But finding the right temperature range isn't enough. Next you need solvents to facilitate the reactions.

A good solvent will leave some stable molecules alone to maintain structure, but will dissolve other more reactive molecules so they can react with each other. The laws of physics (and therefore chemistry) provide an amazing compound for the job: Water. Known as the "universal solvent", it facilitates more kinds of chemical reaction than any other known substance.

So basically, we don't look at "too hot / too cold / needs water" because of the limitations we observe on Earth. We look at it because physics and chemistry tell us these ranges are necessary for matter to arrange itself in to anything fitting our definition of life.

[problemecium]

^ No, no, I get them. I can see where they'd come from too:

A: We know that in at least one instance, life forms made of liquid water and carbon-based polymers can arise, which is better than we can say for any other situation, so it makes sense to look where we know life might be, and

B: If we have any plans to make contact and establish some kind of galactic federation, it'll be a lot easier if they live in a vaguely Earth-like climate and we can identify with them in some sense. For example, in the Mass Effect series we found it much easier to ally with the Asari than the Rachni. So, again, might as well focus the search on those.

Except I disagree with only looking at Earth-like watery worlds around 300K with 1 atmosphere of surface pressure, etc. I feel like it'd be wiser to consider any object that exhibits anomalous chemistry or emissions (e.g. Earth is green despite being made of gray rocks, and its atmosphere is full of O₂).

[JedTech]

I think it is very simple. We have not yet invented the faster-than-light communication technology that all of the cool kids use in the galaxy.

Once we do that, we may just find a new galaxy wide network at our finger tips.

[Hagen von Tronje]

I simply think that the incidence of advanced life is sufficiently rare on both a spatial and temporal scale that it's highly improbable that any signal has or will ever be sent within our detection range within our species' existence. Even if a shockingly high percentage of stars do in fact harbor life at some point in their existence (say, 1 in 1000, even 1 in 100 would make only so much difference here), consider the fraction of a microcosm of time in which our own planet has harbored life capable of generating signals. Now take a nice, generous (but finite) guess as to how long we'll survive. You'll find that the odds do not favor two such civilizations existing anywhere near each other with most even halfway reasonable numbers - it takes something really, really extraordinary, like a multi-million year starfaring civilization, to improve probabilities of overlap. I, personally, don't think such civilizations are likely to be common, if they exist anywhere.

But it has led me to an interesting thought in the past. The wonderful thing about astronomical numbers is that even conservative Drake estimates suggest there are/were millions, billions, or more, planets harboring life throughout the universe. However improbable, the universe is vast enough that the improbable becomes practically inevitable. This suggests to me that somewhere, in a galaxy far, far away (and maybe even long, long ago ), there very possibly are two planets, both harboring some kind of advanced life, maybe both orbiting one star, maybe closely neighboring stars, but close enough that contact became probable - and reality. For those two planets, our fanciful sci fi is a reality. Who knows what wonderous saga played out for those races?

Edited September 2, 2015 by Hagen von Tronje

[GeneralVeers]

Hypothesis, say it with me. Hypothesis.

On topic one thing that nobody ever seems to consider is that maybe we are the advanced ones

I've considered that one. Mentioned it recently in another thread on this forum. So you're not alone in thinking this.

assuming that other life manages to evolve intelligences without killing themselves off with the power of the atom.

This part, on the other hand, is an unwarranted assumption. The doomsday scenario of World War III (including alarmist hype such as "The Day After") was entirely hypothetical from the outset. It certainly could have happened, but so far it has not, and there's no concrete evidence anywhere that it will. Further, there's no reason to assume alien civilizations elsewhere in the universe would follow a history line even remotely similar to our own.

[ComradeWolfe]

Except I disagree with only looking at Earth-like watery worlds around 300K with 1 atmosphere of surface pressure, etc. I feel like it'd be wiser to consider any object that exhibits anomalous chemistry or emissions (e.g. Earth is green despite being made of gray rocks, and its atmosphere is full of O₂).

This begs the question of what we are looking at. Currently, we have no way to detect such anomalous worlds so we just look for planets in general. I do agree that if we later can detect an anomaly, we should check up on it even if it doesn't fit the normal criteria for life.

That said, I still think the basic physical nature of the universe means it's very unlikely that we'll find any life that follows rules vastly different (chemically speaking) from what's at home.

[Aethon]

Op. You're talking about the zoo hypothesis.

https://en.wikipedia.org/wiki/Zoo_hypothesis

consider the fraction of a microcosm of time in which our own planet has harbored life capable of generating signals.

For the past 2 billion years or so the Earth has been sending a signal into space that says our atmosphere is out of equilibrium. The 'red edge' of chlorophyll.

Any ETI worth it's salt knows the Earth has life.

[Rakaydos]

This part, on the other hand, is an unwarranted assumption. The doomsday scenario of World War III (including alarmist hype such as "The Day After") was entirely hypothetical from the outset. It certainly could have happened, but so far it has not, and there's no concrete evidence anywhere that it will. Further, there's no reason to assume alien civilizations elsewhere in the universe would follow a history line even remotely similar to our own.

That we have managed not to kill ourselves with nukes does not mean other species in similar situations did not have their own "cuba missile crisis" during the period between the harnessing of the atom and the colonization of another world. For that matter, we're not entirely out of that zone ourselves, with North Korea having nukes and Iran wanting them.

The majority of inteligent aliens probably never develop technoligy- like dolphins, they perfectly adapt to their enviroment. Many human tribal societies also fit this description, supporting the hypothisis that this is a default state for even inteligent life.

Of the aliens that devlope technoligy, they will inevitably discover the power of the atom eventually. And given how hard space travel is, using the atom makes colonization easier. But it also makes killing themselves off easier. We humans were blessed with stabilized nuclear tensions (we survived the missile crisis), a reasobably borderline world we could potentially colonize (mars), and a planet we can escape with purely chemical propulsion. Other species may not be so lucky.