Six tricks that alien trackers could use(article), page 1
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Topic started on 27-2-2010 @ 01:00 PM by OnceReturned

Six tricks that alien trackers could use

So far, the search for extraterrestrial intelligence has focused on listening for radio signals deliberately sent our way. But even if alien civilisations are not trying to get our attention, their activities could produce detectable signs. Here are a few things we might detect, most of which are discussed in a recent paper by Richard Carrigan of the Fermi National Accelerator Laboratory in Batavia, Illinois.

1.)Earth's cities are visible at night from space because of their artificial lights, so populated exoplanets might give off light pollution of their own. But finding it might not be easy. Even if all the world's electricity were used to produce light, it would still be thousands of times fainter than a glint of sunlight reflected off the Earth's surface.

2.)We could also hunt for evidence of chemical pollutants in the atmospheres of exoplanets. Artificial compounds such as chlorofluorocarbons, or CFCs, could leave traces that might be observed from afar. Because they strongly absorb infrared light at characteristic wavelengths, CFCs may be detectable even when present at concentrations as low as parts per trillion. But it could take an exceptionally sensitive telescope, far beyond the capabilities of present-day instruments, to pick up such traces.

3.)Dumping nuclear waste in a star could leave it with suspiciously large abundances of rare elements produced by nuclear fission, such as technetium or neodymium, which we might detect in its starlight. But creating a recognisable signature may require a colossal amount of material – for example, 100,000 tonnes of technetium, according to an estimate by Guillermo Lemarchand of the National University of Quilmes in Argentina. By contrast, Earth's nuclear reactors have produced only 100 tonnes or so of technetium in the past century, says Richard Carrigan.

4.)An extraterrestrial civilisation might also reveal itself through colossal feats of engineering called Dyson spheres, hypothetical structures that would cocoon stars to collect solar energy. A Dyson sphere would partially or fully block a star’s visible light. But because the sphere would still be warmed by its star, it would radiate infrared light that might be detectable from Earth.

Astronomers have found no Dyson spheres for certain – the few candidates they have flagged up could be explained just as easily as clouds of hydrogen gas, dust engulfing ancient stars or even asteroids.

5.)Rather than blocking the light of just one star, a sprawling extraterrestrial civilisation might build Dyson spheres around many stars, creating a noticeable dark patch in its home galaxy called a Fermi bubble. Like individual Dyson spheres, Fermi bubbles would still radiate heat, making them visible in infrared light.

But finding them could still be tricky. Spiral galaxies, like the Pinwheel galaxy (shown here), are full of dust and dark gaps. Galaxies that are naturally more uniform in brightness, like elliptical galaxies, might be better candidates in the hunt for ET.

6.)An advanced civilisation might modify its parent star to keep its home planet habitable. As stars age and use up the hydrogen in their cores, they swell to become red giants that can engulf surrounding planets and endanger life.

A civilisation could head off disaster by finding a way to extend the life of a star. Doing so would require an extraordinary effort to change conditions within the star by, for example, mixing unused hydrogen from the outer part of the star in with the core, removing some of the star's matter, or adjusting the star's rotation rate to change the pressure inside. Such tampering would give stars unusual properties, providing evidence of powerful alien civilisations.

Source

I am always happy to see the search for ETs given serious attention by the scientific community. Most of these ideas seem fairly outlandish to me, and somewhat unrealistic, but I suppose that it will take some out of the box thinking to make real progress in the search for ETs.

I appreciate what SETI is doing, but sometimes I wonder if they are barking up the wrong tree. They are only able to search such a small part of the sky at once, and even then they could only find a high power, highly directed signal meant for us on earth. I suppose it is better than nothing, but the task of finding intelligent life in space is much, much worse than the proverbial needle in a hay stack.

Anyway, it is encouraging to see that the issue is being attended to. Thoughts?


reply posted on 27-2-2010 @ 03:55 PM by arbiture
reply to post by OnceReturned


I have long thought SETI was a lost cause for one major reason. Earth has been broadcasting radio about 100 years and radar, etc about 60yrs. A naomoment in cosmic time. Now add to that we are converting many of our transmissions to digital from analog. Even SETI admits that this wiil greatly reduce any "leakage" of most communications. The efficiancy digital has over analog means a signal with much lower power, and a greatly reduced footprint, will continue to be the prefered methods.

SETI has long stated that signals have leaked from Earth for about 70yrs. (we started to broadcast with reasonable power in the 1930's) OK, now everything has changed, and this is according to SETI. They have stated as signal clouds move away from Earth their power has decreased expotentialy. They have said a recognizable signal would not have even reached the nearest star.

Last, I think the reason we have not heard anyone but ourselves is, alas there is nothing to hear. Don't misunderstand what I'm saying. I really do believe the universe is awash in life. And there may even be a very large percentage that by our definitions is intelligent. But we confuse an intelligent life form with a technological life form. We assume if they are smart they build radios, surgical scalpels, tennis rackets and nuclear weapons. Wrong, wrong and wrong.

A certain percentage I think will be technological by our definitions, and those we understand. Even technology far beyond us we might see as technology. But then again, as human technology advances even today we see a merging of biology, chemistry, physics, electronics, even neurology. In 100 years it may show no resemblence to "technology" as we understand it today. Why should an alien species 1,000, 1million, 1billion years ahead of us be something we can even see as the creation of a lifeform for x-reasons?

I think any inquisitive lifeforms are going to look at other lifeforms, and if they are purists, try to better understand THAT lifeform. But lets be honest, the main reason we study other life forms, in our case social insects and higher mammals, is not to understand them, but better understand us. Advanced ocean mammels like dolphins, are with out question intelligent, and perhaps in some ways much more advanced then us. We know dolphins evoulved from land based mammels tens of millions of years ago. If on land, like us they need shelter, perhaps clothing, and at some point or another need to master fire. When dolphins moved back to the ocean, all those things above we find critical to our survival they found mute.

We know dolphins know in the first person they are seperate from others, they demonstrate they know each of them is unique (or at least seperate) from others of their own kind and other species. My view is animals like dolphins who don't need to worry about freezing to death, etc, are free to pursue much more esoteric ideas. I view them at least as smart as us and I feel they are likely much more intelligent then we are. We are focused on survival first, then other things. Once dolphins have enough food, who knows, they float around and discuss esoteric mathamatical ideas? I would not put it passed them.

So to summerize, I feel most intelligent beings in the universe are NOT technological beings. So we will never know about them if we don't go to their planet and say howdy. Second a small percentage are technological animals. Third, an advanced species may need be just a little bit ahead of us to be incomprehensible to us. Look to human history, and go back just 1,000years. Ask the average knight whats the fastest way to send information? He will say first by a runner with the message hand delivered, or better yet ride a horse, or as they did in China with the great wall for ages, smoke signals. I don't think we can comprehend what an advanced race will communicate. But even in the end if we know how aliens communicate we most likely will not understand what they are trying to say.


reply posted on 28-2-2010 @ 04:00 PM by big_BHOY
Originally posted by Sinter Klaas
Ok Nice !

I'm gonna give you my thoughts on them.

1. This would be impossible right now. We find most exoplanets, observing stars to find the ones that wobble.

2.Isn't this radiation faded out by every other radiation source ?

3. Advanced probably means intelligent. They would probably not even thinking about meddling with a star.

4. We can assume the same intelligence is not gonna black out their solar system.

5. See question 4.

6. Common ! They would just move to another planet.



Most of these ideas seem fairly outlandish to me, and somewhat unrealistic, but I suppose that it will take some out of the box thinking to make real progress in the search for ETs.


Out of the box thinking ?
I think they are limited by their own imagination.

Unrealistic is at the least ! IMHO


1) Obviously it's way beyond our means currently. The whole publication is hypothetical way of finding advanced life.

Once technology advances enough, I wouldn't put it past us to develop a way to direct image planets that are within a few light years. When that day comes, then it could be possible to detect. Then again maybe not.

2) Since it specifically states "CFCs may be detectable even when present at concentrations as low as parts per trillion." then obviously not.

3) If a race is advanced enough, then I can easily see them modifying or playing around with stars if it suits their needs.

4) They could use something like a 'dyson swarm', ringworld etc. It would still allow light to get through. Even if they built a 'dyson sphere' & completely blacked-out their home planet(s). There are still ways to provide sunlight. They could put mirrors on the outside of the sphere & re-direct some of the light to wherever they want. They could use satellites to provide 'artifical sunlight' which are powered by energy beamed from the sphere etc.

The James bond movie 'Die Another Day' shows a good example of how it might potentially be done.

Put it this way, if they are advanced enough to create a 'dyson sphere', then I'm sure they are capable of re-directing some of the light to their home planet or creating an artifical light.

5) Exact same as 4. Re-direct some of the light directly using mirrors on the outside of the sphere, or they could do it artifically using orbiting satellites.

6) It might not be as simple as that! What if they need a strict set conditions to live on. They might not have developed FTL technology & the nearest habitable star could be hundreds of light years away. So no possible way of moving a whole planet worth of inhabitants on such a long journey.

If they have the capability of 'prolonging' or repairing their home stars lifespan, then it's far more logical/efficient/timely to go down that route, rather than having to uproot a whole planet & start over from scratch again.

All methods of detection are well out of our league at this moment, but it's entirely possible in a few hundred years that it might not be!
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