Aliens?

[Gargamel]

Originally Posted by UnderseaLcpl

I agree, but I also believe that there is no life outside of this planet that will ever be of any use or interest to us beyond scientific curiousity.

The problem with that statement is that Xenobiology is an unknown sciece. Without ever studying anything, there is no way to ever say that is true or not.

If there was any reachable life that could teach us anything useful, we'd have long since detected their communications signals. If such life was capable of reasonable interstellar travel, we'd have long since discovered both their communications signals and possibly the exhaust of their drives, provided they were engaged in the last 30 years or so.

There are almost an infinite number of frequencies that could be broadcast on, and we have to directionally focus our receivers to listen for these signals. Now multiply that by the number of stars to listen to.... You get the idea why it's taking so long. And then you have to process each glump of data to figure out whats out there. (Coincedentally, if you want to help with that, you can join me help filter the data while your computer is not doing anything functional by joining BOINC and installing the SETI@Home project (There's an enigma decoding project too for you subnuts ), and they make for decent screensavers).

Your saying we should be able to see the exhaust from a single ship within 30 years travel, when we are having difficulty detecting asteroids the size of small towns that are a few days/weeks away?

For all practical purposes, we are stuck here, and nobody will ever know we are here.

Probably true, but nothing ventured nothing gained. Kennedy's to the moon speech is coming to mind.

[UnderseaLcpl]

Originally Posted by Gargamel

The problem with that statement is that Xenobiology is an unknown sciece. Without ever studying anything, there is no way to ever say that is true or not.

True enough, but I still think the probability of finding anything worthwhile is small enough that there is no need to actively invest in xenobiology or much beyond localized space exploration, not including orbital observatories.

There are almost an infinite number of frequencies that could be broadcast on, and we have to directionally focus our receivers to listen for these signals. Now multiply that by the number of stars to listen to.... You get the idea why it's taking so long. And then you have to process each glump of data to figure out whats out there.

I used to think the same thing myself. However, once I began studying as a radio operator and took the time to get into the nuances of advanced elements like antennae theory and waveform propagation, I am no longer so sure.

The means by which SETI attempts to detect transmissions through ground-based directional receivers is actually kind of silly. Any type of long-range communications, such as those that would be used to communicate between planets or between a planet and a long-range probe, rely upon powerful transmitters that must operate on relatively long wavelengths to overcome interference.

Think of it this way: a large electromagnetic wave is a lot like a large wave of water, or a very loud sound. It may hit obstacles and suffer some loss of integrity as a result, but the wave is still mostly intact unless it runs into something bigger than it is. Even then, it retains enough energy to bounce off of whatever it hits and then bounce again multiple times and can still be received by the intended recipient. However, it will also be recieved by anyone else within "earshot".

In the void of space, there is virtually nothing that can block a large wave, so it is very likely that we would have detected such transmissions by now if they emanated from a reachable source.

Now, it is possible that an advanced civilization might employ some kind of advanced directional transmission technology that had enough raw power to overcome EMI and enough accuracy to reach a cosmically distant receiver, but such a method of transmission would generate enough "bleed-off" radiation that it would be detectable from a tremendous distance. There is no such thing as a truly "directional" transmitter aside from a physical connection. All antennae are sources omni-directional radiation to some degree, and when you consider the amount of power that it takes to transmit a short-wave signal or a microwave signal reliably over a long distance, those power requirements would be very high.

Hence, we would detect the "spilled" radiation from either source quite easily, assuming we employed an omni-directional reciever in very high orbit, away from the tremendous destructive interference of the earth's atmosphere and magnetospher. Beyond that, it's just a matter of looking for recurring instances of patterned EMF, which a computer can do easily, and interpreting the data.

This is why I say SETI's approach is kind of silly. If they really wanted to find evidence of extraterrestrial intelligence, they'd abandon this ridiculous approach of using ground-based dish receivers tuned to look for specific frequencies from specific sources, a few at a time. An orbital omni-directional receiver, which essentially amounts to a large, lightweight EM tuning-fork in space would serve the same purpose and do it much better.

(Coincedentally, if you want to help with that, you can join me help filter the data while your computer is not doing anything functional by joining BOINC and installing the SETI@Home project.

Thanks for the info and the links I'll take a look and consider joining the effort, provided it doesn't add any unreasonable strain to my already somewhat-taxed system resources. I really need to invest in a newer computer.

As much as I complain about SETI, the organization is there already, and if they have a way for me to help I might as well try it.

Your saying we should be able to see the exhaust from a single ship within 30 years travel, when we are having difficulty detecting asteroids the size of small towns that are a few days/weeks away?

Yes, that's what I'm saying. You're thinking in terms of active detection. Asteroids are small, cold rocks in space. To detect them, we have to actively paint them with a signal of sufficient power to generate a return, but without so large a wavelength as to miss the object entirely or bounce in a direction not aimed at our receivers. Think of it as looking for a periscope that is millions of miles away with decimetric radar.

A spacegoing vessel that is capable of interstellar or even interplanetary travel at practicable speeds, on the other hand, would generate a tremendous amount of heat radiation by virtue of the energy needed to accelerate its mass, and then slow it down on approach. Even for a very lightweight vessel, we're talking about trillions of kilojoules of energy. That kind of energy would show up on our radio telescopes.

Probably true, but nothing ventured nothing gained. Kennedy's to the moon speech is coming to mind.

And what did we ever get from the moon? It cost us the equivalent of $150 billion or so in today's currency just to land there once and get a some rock samples. Then we went there repeatedly. A lot of scientific data was gleaned in the process, but how much of it do we ever use? How much of that money would have been better-directed at developing something practical, like satellite technology or economic priorities?

[Sailor Steve]

I'm disappointed in you guys. After all, Superman's an alien.

[STEED]

There is no life out there and sooner the world sees that the sooner we can all go mad.

Sorry...Barking mad.

[Growler]

Whether there is other life in the universe or there isn't, either way, the ramifications are staggering. I mean, after all, if we as a planet are entirely unique in all of the universe, haven't we got better things to be out there doing than fighting amongst ourselves? We're like unsupervised kids in an empty amusement park with free tickets to everything, and we're fighting over who stands in line where. And if there is other life out there, wouldn't we be better served by not looking like an unruly gang of kids absent parents?

[TLAM Strike]

Originally Posted by UnderseaLcpl

I agree, but I also believe that there is no life outside of this planet that will ever be of any use or interest to us beyond scientific curiousity. If there was any reachable life that could teach us anything useful, we'd have long since detected their communications signals. If such life was capable of reasonable interstellar travel, we'd have long since discovered both their communications signals and possibly the exhaust of their drives, provided they were engaged in the last 30 years or so.

The only thing we will likely ever discover within our very limited reach, which is made so by the laws of physics and sheer practicability, are dead planets and perhaps some primitive life-forms that are not adapted to life on Earth or any planet or moon in our solar system, making them unexploitable.

For all practical purposes, we are stuck here, and nobody will ever know we are here.

Well just finding life forms that live in extremely harsh environments could be useful in the long run. Imagine finding a lifeform that survives on Europa a moon deep in Jupiter's radiation belt, a complex lifeform that can survive that would be interesting to study to learn how it survives such radiation exposure.

Also outside (or maybe inside) our star system just finding remains of an extinct alien civilization would be worth any $ spent on going there. Who knows what technologies or ideas they left behind.

Originally Posted by UnderseaLcpl

True enough, but I still think the probability of finding anything worthwhile is small enough that there is no need to actively invest in xenobiology or much beyond localized space exploration, not including orbital observatories.



I used to think the same thing myself. However, once I began studying as a radio operator and took the time to get into the nuances of advanced elements like antennae theory and waveform propagation, I am no longer so sure.

The means by which SETI attempts to detect transmissions through ground-based directional receivers is actually kind of silly. Any type of long-range communications, such as those that would be used to communicate between planets or between a planet and a long-range probe, rely upon powerful transmitters that must operate on relatively long wavelengths to overcome interference.

Think of it this way: a large electromagnetic wave is a lot like a large wave of water, or a very loud sound. It may hit obstacles and suffer some loss of integrity as a result, but the wave is still mostly intact unless it runs into something bigger than it is. Even then, it retains enough energy to bounce off of whatever it hits and then bounce again multiple times and can still be received by the intended recipient. However, it will also be recieved by anyone else within "earshot".

In the void of space, there is virtually nothing that can block a large wave, so it is very likely that we would have detected such transmissions by now if they emanated from a reachable source.

Now, it is possible that an advanced civilization might employ some kind of advanced directional transmission technology that had enough raw power to overcome EMI and enough accuracy to reach a cosmically distant receiver, but such a method of transmission would generate enough "bleed-off" radiation that it would be detectable from a tremendous distance. There is no such thing as a truly "directional" transmitter aside from a physical connection. All antennae are sources omni-directional radiation to some degree, and when you consider the amount of power that it takes to transmit a short-wave signal or a microwave signal reliably over a long distance, those power requirements would be very high.

Hence, we would detect the "spilled" radiation from either source quite easily, assuming we employed an omni-directional reciever in very high orbit, away from the tremendous destructive interference of the earth's atmosphere and magnetospher. Beyond that, it's just a matter of looking for recurring instances of patterned EMF, which a computer can do easily, and interpreting the data.

This is why I say SETI's approach is kind of silly. If they really wanted to find evidence of extraterrestrial intelligence, they'd abandon this ridiculous approach of using ground-based dish receivers tuned to look for specific frequencies from specific sources, a few at a time. An orbital omni-directional receiver, which essentially amounts to a large, lightweight EM tuning-fork in space would serve the same purpose and do it much better.


Thanks for the info and the links I'll take a look and consider joining the effort, provided it doesn't add any unreasonable strain to my already somewhat-taxed system resources. I really need to invest in a newer computer.

As much as I complain about SETI, the organization is there already, and if they have a way for me to help I might as well try it.


Yes, that's what I'm saying. You're thinking in terms of active detection. Asteroids are small, cold rocks in space. To detect them, we have to actively paint them with a signal of sufficient power to generate a return, but without so large a wavelength as to miss the object entirely or bounce in a direction not aimed at our receivers. Think of it as looking for a periscope that is millions of miles away with decimetric radar.

A spacegoing vessel that is capable of interstellar or even interplanetary travel at practicable speeds, on the other hand, would generate a tremendous amount of heat radiation by virtue of the energy needed to accelerate its mass, and then slow it down on approach. Even for a very lightweight vessel, we're talking about trillions of kilojoules of energy. That kind of energy would show up on our radio telescopes.



And what did we ever get from the moon? It cost us the equivalent of $150 billion or so in today's currency just to land there once and get a some rock samples. Then we went there repeatedly. A lot of scientific data was gleaned in the process, but how much of it do we ever use? How much of that money would have been better-directed at developing something practical, like satellite technology or economic priorities?

I agree there are problems with the way SETI looks. I'm a strong believer in "Visual SETI" that is searching space for mega-structures built by highly advanced species. Also scanning a different parts of the spectrum for evidence of advanced spacecraft in flight (when gamma ray busters were 1st discovered some assumed they were either the star drives of advanced spacecraft or the "Big Honking Space Guns" of some interstellar war.)

[UnderseaLcpl]

Originally Posted by TLAM Strike

Well just finding life forms that live in extremely harsh environments could be useful in the long run. Imagine finding a lifeform that survives on Europa a moon deep in Jupiter's radiation belt, a complex lifeform that can survive that would be interesting to study to learn how it survives such radiation exposure.

It would be interesting to study, I'll give you that, but I think that what would be more useful in the long-run is devoting the resources needed to undertake such a mission to solving practical problems on the perfectly good planet we already have.

To clarify, I'm not saying that we shouldn't ever attempt to explore other planets or other star systems. I'm just saying that we're not quite ready for it yet, and I think that throwing public resources at faint hopes that there might be some form of life we might learn something useful from is not the wisest use of said resources at the moment.

Consider: As it is now, private industry and governments alike are already throwing considerable resources into developing more efficient energy-generation technology. Eventually, they'll succeed. We'll need that tech to develop a viable platform for extraplanetary or extrasolar exploration anyway, so why invest resources in detecting something we can't reach and have no use for at the moment?

Also outside (or maybe inside) our star system just finding remains of an extinct alien civilization would be worth any $ spent on going there. Who knows what technologies or ideas they left behind.

An attractive possibility, but not a probable one. Even if there were an extinct alien civilization within our currently very limited reach, odds are that nothing useful would remain.

As a thought experiment, imagine that we suddenly went extinct today. We've been sending and receiving organized high-power transmission en masse for almost a hundred years. No advanced civilization within at least 30 light-years (generously rounding down) has responded. If a civilization existed that was at least equivalent to ours in terms of technology, they would have responded by now, or we would have at least picked up their broadcasts, so we can safely assume that that no such civilization exists within 30 light-years.

Now imagine what would be left of our civilization by the time they got here. There wouldn't be much left, even if they were somehow capable of travelling at light-speed. All of our most advanced technology requires constant maintenance and power and energy of some type. There would be no useful record that they didn't already understand.

I agree there are problems with the way SETI looks. I'm a strong believer in "Visual SETI" that is searching space for mega-structures built by highly advanced species. Also scanning a different parts of the spectrum for evidence of advanced spacecraft in flight (when gamma ray busters were 1st discovered some assumed they were either the star drives of advanced spacecraft or the "Big Honking Space Guns" of some interstellar war.

I'll have to do more research on visual SETI before I can from an opinion on that, but at least we agree on something

Originally Posted by Gargamel

That's like the Europeans saying there probably isn't anything worth looking for on the other side of this ocean, so let's not go looking

That is not the same thing. Columbus was already aware that the world was roughly global in structure, and the Greeks and Persians had figured that out mathematically long before him.

In this case, mathematics strongly suggest that there is nothing reachable.

Originally Posted by Gargamel

What I understand from that is that you are assuming they are using a transmitter designed for insterstellar communications. This is not what SETI is looking for. They are looking for normal everyday radiation coming from a civilization, along with any possible "stellar beacons".

Then either you have misunderstood or I have offered an inadequate explanation. Probably the latter. I will explain further when I have more time. Bear in mind, I'm not saying you are wrong.

At the moment, though, I have to go to work.


edit-2 Goddamnit! No sooner do I finish editing this post after getting out of the shower when I get a call saying my work order has been cancelled. <double-facepalm>

Not long ago smoke and huge fires were the means of long distant signaling.

Why assume that we can detect any type advanced signaling?
Or any type advanced Space Crafts Drive systems?

We've barely scratched the Stealth surface in the last 50 years.

So detection based on our technology is like trying to detect a pebble thrown in the Red Sea from New York.
We probably have a better chance of actually doing that!

And if there is intellegent life out there?
They probably feel about as good about visiting us,
as I do about walking through Harlem after dark with a wad of money taped to my forehead.

[Platapus]

I like that Calvin and Hobbs comic : "the surest sign that there is intelligent life out there is that they have never chosen to visit us"

We also can barely detect Ground Side Aliens crossing our borders.
And they use our technology!
How the hell are we going to detect off planet Aliens?

[TLAM Strike]

Originally Posted by privateer

Not long ago smoke and huge fires were the means of long distant signaling.

Why assume that we can detect any type advanced signaling?
Or any type advanced Space Crafts Drive systems?

We've barely scratched the Stealth surface in the last 50 years.

So detection based on our technology is like trying to detect a pebble thrown in the Red Sea from New York.
We probably have a better chance of actually doing that!

The Why...

The Space Shuttle's much main engines could be detected past the orbit of Pluto. The Space Shuttle's manoeuvering thrusters could be seen as far as the asteroid belt. And even a puny ship using ion drive to thrust at a measly 1/1000 of a g could be spotted at one astronomical unit.

If the spacecraft are torchships, their thrust power is several terawatts. This means the exhaust is so intense that it could be detected from Alpha Centauri. By a passive sensor.

And if there is intellegent life out there?
They probably feel about as good about visiting us,
as I do about walking through Harlem after dark with a wad of money taped to my forehead.

Bring'em on!
And I hope they come in at light speed those punks!

We will have a few thousand years notice to advanced our tech and build a fleet to ships to wait for them...

Originally Posted by UnderseaLcpl

It would be interesting to study, I'll give you that, but I think that what would be more useful in the long-run is devoting the resources needed to undertake such a mission to solving practical problems on the perfectly good planet we already have.

This planet and the and whole stinking universe it sits in wants to kill us.

We got to get the heck out of here!

An attractive possibility, but not a probable one. Even if there were an extinct alien civilization within our currently very limited reach, odds are that nothing useful would remain.

As a thought experiment, imagine that we suddenly went extinct today. We've been sending and receiving organized high-power transmission en masse for almost a hundred years. No advanced civilization within at least 30 light-years (generously rounding down) has responded. If a civilization existed that was at least equivalent to ours in terms of technology, they would have responded by now, or we would have at least picked up their broadcasts, so we can safely assume that that no such civilization exists within 30 light-years.

Now imagine what would be left of our civilization by the time they got here. There wouldn't be much left, even if they were somehow capable of travelling at light-speed. All of our most advanced technology requires constant maintenance and power and energy of some type. There would be no useful record that they didn't already understand.

Well that assumes they develop technologically evenly in all departments. What if they make a sudden leap in one and the others by accident or design remain undeveloped?
They might get here and be like "OMG what are these transistor things!"

I'll have to do more research on visual SETI before I can from an opinion on that, but at least we agree on something

http://www.msnbc.msn.com/id/28916124...science-space/

Great thing from my perspective is that it allows for possible communication with both less advanced and more advanced civilizations. A less advanced civ might put a giant mirror on their planet to flash out a message or a more advanced one might build a giant structure with a message.

[Gargamel]

Originally Posted by UnderseaLcpl

True enough, but I still think the probability of finding anything worthwhile is small enough that there is no need to actively invest in xenobiology or much beyond localized space exploration, not including orbital observatories.

That's like the Europeans saying there probably isn't anything worth looking for on the other side of this ocean, so let's not go looking (Although politically today, they may agree).

However how highly unlikely it is, could we risk the chance that a superior or group of superior intelligences are just waiting for us to attempt contact, so they can go "Oh Hai! Welcome to the club, Xithinbob over there makes a mean martini, feel free to use the pool!"

I used to think ...... and interpreting the data.

What I understand from that is that you are assuming they are ussing a transmitter designed for insterstellar communications. This is not what SETI is looking for. They are looking for normal everyday radiation coming from a civilization, along with any possible "stellar beacons".

Thanks for the info and the links I'll take a look and consider joining the effort, provided it doesn't add any unreasonable strain to my already somewhat-taxed system resources. I really need to invest in a newer computer.

BOINC is really cool. They have many many many different cloud based supercomputing problems they are working to solve (plate tectonics, weather, chess, gravity waves, etc etc) and the apps only run in the background when your processor is not being utilized (ie screensaver). It's been my screensaver for many years.

As much as I complain about SETI, the organization is there already, and if they have a way for me to help I might as well try it.

[TLAM Strike]

Originally Posted by UnderseaLcpl

Yes, that's what I'm saying. You're thinking in terms of active detection. Asteroids are small, cold rocks in space. To detect them, we have to actively paint them with a signal of sufficient power to generate a return, but without so large a wavelength as to miss the object entirely or bounce in a direction not aimed at our receivers. Think of it as looking for a periscope that is millions of miles away with decimetric radar.

My astronomy professor was just talking about them doing that down at Aricibo when he was there two years ago. At night Aricibo sends out "pings" and paints the asteroid belt and other places to search for and image them.