Why haven’t we detected a signal from intelligent aliens yet?

Obtenebrotar said:
Is that why I had to explain it to you to try to prove to you I am smart?:crybaby:
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I don't read or respond to your dumb obsessions with the null hypothesis, because the null hypothesis is both boring to discuss and you were using it wrong.

Who the fuck runs around blabbing constantly about the null hypothesis?

If you used it correctly you would be an agnostic, because from the POV of experimental science there is always a measurable probability the null hypothesis will be rejected, and the alternative hypothesis affirmed. Otherwise, nobody would do science.

If I have never mentioned Martin Van Buren or Willie Mays on this board before, does that mean I don't know about them? :laugh:
 
One problem here is that we don't know how long electromagnetic waves (aka 'radio' waves) are used by an advanced civilization. It is entirely possible that we haven't heard from such a civilization simply because we missed the interval where they send such waves out. We don't know enough at this point to even have a clue how far some other civilization(s) have gotten.
 
Cypress said:
I don't read or respond to your dumb obsessions with the null hypothesis, because the null hypothesis is both boring to discuss and you were using it wrong.

Who the fuck runs around blabbing constantly about the null hypothesis?

If you used it correctly you would be an agnostic, because from the POV of experimental science there is always a measurable probability the null hypothesis will be rejected, and the alternative hypothesis affirmed. Otherwise, nobody would do science.

If I have never mentioned Martin Van Buren or Willie Mays on this board before, does that mean I don't know about them? :laugh:
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LOL. You seem really upset. I have to admit it is kinda fun to see you when you've been caught.

You expend SO MUCH TIME telling others how you are smarter than they are and they must "frantically google" everything. This is hilarious.

Maybe this can be a lesson for you: sometimes people know stuff you don't. Sometimes people have more experience in things than you do. Don't be a dick about it.
 
T. A. Gardner said:
One problem here is that we don't know how long electromagnetic waves (aka 'radio' waves) are used by an advanced civilization. It is entirely possible that we haven't heard from such a civilization simply because we missed the interval where they send such waves out. We don't know enough at this point to even have a clue how far some other civilization(s) have gotten.
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Personally I hold out the possibility that there may be advanced life but like the VAST majority of human existence, they simply don't generate any EM signals yet.

I don't think anyone would say that Medieval people weren't an "advanced life form" but they had no EM signature to speak of. The development of EM generating technology is NOT a necessarily guaranteed outcome to an advanced life form.

So it always fascinates me when people have this view that if they haven't found an EM it must mean there is no advanced life forms out there. It's missing a vast swath of options for the possibility of it.
 
T. A. Gardner said:
One problem here is that we don't know how long electromagnetic waves (aka 'radio' waves) are used by an advanced civilization. It is entirely possible that we haven't heard from such a civilization simply because we missed the interval where they send such waves out. We don't know enough at this point to even have a clue how far some other civilization(s) have gotten.
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We understand the EM spectrum quite well, and it's nearly inconceivable that a technological civilization at some point in their development would not discover that radio and microwave frequencies are the only part of the EM spectrum that can send information over long distances, whether it be for communication, navigation, etc.
 
Obtenebrator said:
Personally I hold out the possibility that there may be advanced life but like the VAST majority of human existence, they simply don't generate any EM signals yet.

I don't think anyone would say that Medieval people weren't an "advanced life form" but they had no EM signature to speak of. The development of EM generating technology is NOT a necessarily guaranteed outcome to an advanced life form.

So it always fascinates me when people have this view that if they haven't found an EM it must mean there is no advanced life forms out there. It's missing a vast swath of options for the possibility of it.
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Exactly. That's my point. We as a species have been transmitting radio waves into space for something like .01% of our existence and we don't know if at some point in the future we stop doing that because the technology has become obsolete.
 
Cypress said:
We understand the EM spectrum quite well, and it's nearly inconceivable that a technological civilization at some point in their development would not discover that radio and microwave frequencies are the only part of the EM spectrum that can send information over long distances, whether it be for communication, navigation, etc.
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It is also very conceivable that that technology lasts for say 300 to 500 years and then is surpassed by something else. That means unless their EM waves pass through Earth in that 300 to 500 year window and we are listening for them, they go undetected. For example, some advanced civilization transmits from 300 years before going silent (on to some other technology) but those waves passed through the Earth from 1200 AD to 1500 AD. We missed our chance to find them that way.
 
T. A. Gardner said:
Exactly. That's my point. We as a species have been transmitting radio waves into space for something like .01% of our existence and we don't know if at some point in the future we stop doing that because the technology has become obsolete.
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radio waves my reach the closest intelligent alien in approximately 2936 AD
 
T. A. Gardner said:
It is also very conceivable that that technology lasts for say 300 to 500 years and then is surpassed by something else. That means unless their EM waves pass through Earth in that 300 to 500 year window and we are listening for them, they go undetected. For example, some advanced civilization transmits from 300 years before going silent (on to some other technology) but those waves passed through the Earth from 1200 AD to 1500 AD. We missed our chance to find them that way.
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The easiest explanation for why we haven't detected artificial footprints in the radio EM frequences is because there is no one out there, at least in our part of the galaxy.

That is an easier and more satisfactory explanation than explaining the silence away by supposing everyone else is using exotic forms of communication we don't know about.

On the other hand, it could just be incredibly difficult to detect and pinpoint an artificial signal in the vast natural background of cosmic radio frequency noise.

Exotic forms of communication: ....We have thought of exotic forms of communication ourselves. But sending information via quantum entanglement seems to violate basic laws of physics. Sending information via wormholes might be theoretically possible, but wormholes themselves are theoretical, no one has ever seen tangible evidence for one.

The EM spectrum is such a ubiquitous and fundamental property of the universe, it's hard to imagine an intelligent technological species not using it to their advantage for communication and navigation.
 
T. A. Gardner said:
Exactly. That's my point. We as a species have been transmitting radio waves into space for something like .01% of our existence and we don't know if at some point in the future we stop doing that because the technology has become obsolete.
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Even if we stopped using radio frequencies, the light cone we have already transmitted in theory will travel in perpetuity and wash over the rest of the galaxy, and could be at least potentially detectable in our region of the galaxy, if there is anyone out there now or thousands of years in the future. .
 
Cypress said:
The easiest explanation for why we haven't detected artificial footprints in the radio EM frequences is because there is no one out there, at least in our part of the galaxy.

That is an easier and more satisfactory explanation than explaining the silence away by supposing everyone else is using exotic forms of communication we don't know about.

On the other hand, it could just be incredibly difficult to detect and pinpoint an artificial signal in the vast natural background of cosmic radio frequency noise.

Exotic forms of communication: ....We have thought of exotic forms of communication ourselves. But sending information via quantum entanglement seems to violate basic laws of physics. Sending information via wormholes might be theoretically possible, but wormholes themselves are theoretical, no one has ever seen tangible evidence for one.

The EM spectrum is such a ubiquitous and fundamental property of the universe, it's hard to imagine an intelligent technological species not using it to their advantage for communication and navigation.
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Our intelligent, technological, species didn't use it for something like 10,000 years and has only been using it where the signals could escape into space for something like 100 years. Another intelligent, technological, species might not even bother with it due to some conditions unique to their world, we just don't know enough to know.
 
T. A. Gardner said:
Our intelligent, technological, species didn't use it for something like 10,000 years and has only been using it where the signals could escape into space for something like 100 years. Another intelligent, technological, species might not even bother with it due to some conditions unique to their world, we just don't know enough to know.
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Since 1970, science fiction enthusiasts and Star Trekies had me convinced that life is inevitable in the presence of liquid water, and where there is biological evolution, intelligence inevitably evolves. The galaxy should be pregnant with sentient life.

50 years of silence at SETI doesn't prove anything, but it is reason enough to give pause.

If we hear nothing but silence for the next hundred years, we should start considering the possibility we are the only sentient civilization in the galaxy.

I am not talking just about sentient civilizations that are contemporaneous with our own. If Star Trek was right, the galaxy should be awash in artificial signals whose light cones occasionally intersect Earth. An artificial signal from somewhere in the Sagittarius cluster could be from a civilization thousands of years ago and long gone at this point.
 
Cypress said:
Even if we stopped using radio frequencies, the light cone we have already transmitted in theory will travel in perpetuity and wash over the rest of the galaxy, and could be at least potentially detectable in our region of the galaxy, if there is anyone out there now or thousands of years in the future. .
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That completely ignores how EM waves travel. They may travel in perpetuity but they will only pass by each place once and they will get weaker and less detectable the farther they travel.

Then it is a case of assuming that they will modify and create waves in the exact way that we can readily see them. This is not the case as our own technology has shown. An AM radio can only detect noise on an FM frequency. An early 9600 baud modem can't make any sense of a 28.8K modem's signals. Low voltage signals added to an AC require knowing to filter out a certain voltage to be able to understand the signals. Current satellite TV signals are sent scrambled. SETI picks up radio signals all the time. It is just a question of finding anything in them that was produced by an intelligent species.
 
Poor Richard Saunders said:
That completely ignores how EM waves travel. They may travel in perpetuity but they will only pass by each place once and they will get weaker and less detectable the farther they travel.

Then it is a case of assuming that they will modify and create waves in the exact way that we can readily see them. This is not the case as our own technology has shown. An AM radio can only detect noise on an FM frequency. An early 9600 baud modem can't make any sense of a 28.8K modem's signals. Low voltage signals added to an AC require knowing to filter out a certain voltage to be able to understand the signals. Current satellite TV signals are sent scrambled. SETI picks up radio signals all the time. It is just a question of finding anything in them that was produced by an intelligent species.
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A civilization that uses radio band frequencies for a thousand years is going to emit a light cone for a thousand years. It's not a one time event. I think the assumption was that the galaxy was supposed to be pregnant with sentient life, so that's a lot of light cones washing over the galaxy

It's a good point though to highlight the difficulty in detecting artificial EM footprints.

I don't know much about the future of communications, so I can't say anything intelligent about it. But I haven't heard SETI say it is hopeless and pointless to monitor the galactic radio band frequencies.
 
Cypress said:
A civilization that uses radio band frequencies for a thousand years is going to emit a light cone for a thousand years. It's not a one time event. I think the assumption was that the galaxy was supposed to be pregnant with sentient life, so that's a lot of light cones washing over the galaxy

It's a good point though to highlight the difficulty in detecting artificial EM footprints.

I don't know much about the future of communications, so I can't say anything intelligent about it. But I haven't heard SETI say it is hopeless and pointless to monitor the galactic radio band frequencies.
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Lots of things in the universe emit radiation of various wave lengths. Natural sources can easily drown out what humans produce.
The thing about a light cone is it spreads out. That means a single receiver one light month away will get a signal that is magnitudes larger than a single receiver one light year way.

I am not familiar with how narrow SETI's focal point is for listening. If they have a wide range then anything in that range will be received and strong signals can drown out weak signals. If they have a narrow focus then it takes a long time to search the entire sky.

SETI isn't hopeless but simply turning on a receiver will get you nothing of value. It's a process to try to eliminate any natural sources and then hope you are searching the right way to find something that seems intelligent.
 
Poor Richard Saunders said:
Lots of things in the universe emit radiation of various wave lengths. Natural sources can easily drown out what humans produce.
The thing about a light cone is it spreads out. That means a single receiver one light month away will get a signal that is magnitudes larger than a single receiver one light year way.

I am not familiar with how narrow SETI's focal point is for listening. If they have a wide range then anything in that range will be received and strong signals can drown out weak signals. If they have a narrow focus then it takes a long time to search the entire sky.

SETI isn't hopeless but simply turning on a receiver will get you nothing of value. It's a process to try to eliminate any natural sources and then hope you are searching the right way to find something that seems intelligent.
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Agree that the EM search is for a needle in a haystack, but EM is just one data point. I think we should look at all the evidence.

What I am saying is that when the Drake Equation first came out, there were all kinds of estimates that there were going to be millions of advanced civilizations in our galaxy alone.

Taken as a whole, the radio silence in the EM spectrum; the fact we have not made any really dramatic progress in 70 years in replicating the abiogenesis of life; and our increasing awareness that life on Earth seems to have required a perfect storm of conditions, in sum makes me place my bet on the proposition that advanced intelligent life in our galaxy was always exceptionally rare, if it ever existed.
 
Even if the universe is teaming with intelligent life, consider this:

Say we sent a message in 1970 and there is a close civilization, a mere 80 light years from us, the signal reaches this civilization in 2050, and they respond. in 2130, we will get the response.

That is in the BEST of circumstances.

Let's say there was an advanced civilization a mere 10 light years away - but it died out 5 billion years ago. We are dealing with vast distances and vast amounts of time. Even if there were millions of advanced civilizations across the galaxy, the chances of ever making contact are infinitesimally small.
 
When we do, it will be by chance. We probably haven't even touched more than 1% of the night sky. I also wonder how much red shift we'd have to adjust for in order to get some signal from stars that are moving...
 
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