Slashdot Mirror
Spot ET's Waste Heat For Chance To Find Alien Life
mdsolar passes along this selection from New Scientist describing a (comparatively) low-tech means of scanning the skies for extraterrestrial civilizations: The best-known technique used to search for tech-savvy aliens is eavesdropping on their communications with each other. But this approach assumes ET is chatty in channels we can hear. The new approach, dubbed G-HAT for Glimpsing Heat from Alien Technologies, makes no assumptions about what alien civilisations may be like.
"This approach is very different," says Franck Marchis at the SETI Institute in California, who was not involved in the project. "I like it because it doesn't put any constraints on the origin of the civilisation or their willingness to communicate." Instead, it utilises the laws of thermodynamics. All machines and living things give off heat, and that heat is visible as infrared radiation. The G-HAT team combed through the catalogue of images generated by the Wide-field Infrared Survey Explorer, or WISE, which released an infrared map of the entire sky in 2012. A galaxy should emit about 10 per cent of its light in the mid-infrared range, says team leader Jason Wright at Pennsylvania State University. If it gives off much more, it could be being warmed by vast networks of alien technology – though it could also be a sign of more prosaic processes, such as rapid star formation or an actively feeding black hole at the galaxy's centre.
"This approach is very different," says Franck Marchis at the SETI Institute in California, who was not involved in the project. "I like it because it doesn't put any constraints on the origin of the civilisation or their willingness to communicate." Instead, it utilises the laws of thermodynamics. All machines and living things give off heat, and that heat is visible as infrared radiation. The G-HAT team combed through the catalogue of images generated by the Wide-field Infrared Survey Explorer, or WISE, which released an infrared map of the entire sky in 2012. A galaxy should emit about 10 per cent of its light in the mid-infrared range, says team leader Jason Wright at Pennsylvania State University. If it gives off much more, it could be being warmed by vast networks of alien technology – though it could also be a sign of more prosaic processes, such as rapid star formation or an actively feeding black hole at the galaxy's centre.
obligatory picture of that crazy aliens guy goes here.
Either we will have located the home world of the Quagaars, or it'll turn out to be a garbage pod.
#DeleteChrome
These are infrared array cameras mounted of space telescopes. How high tech do you want? http://wise.ssl.berkeley.edu/
Such assumptions as, that alien life has not found a way around the Second Law of Thermodynamics?
"Screw Sun, cross-platform will never work. Let's move on and steal the Java language." - Visual J++ Product Manager
Basically, this method of searching for aliens returns a positive whenever there is something producing heat which we don't see/understand. I have a feeling that the universe is quite full of such things. But maybe explaining these will help us make scientific advances. When astronomers first discovered a pulsar, they labeled the signal LGM for "little green men". But since then, we learned a lot about astronomy. Explaining apparent anomalies is good for science, and if you want to make the process sexier by talking about possible alien civilizations, I don't see much harm.
with waste heat. never thought of that.
An alien civilization using this technique, would certainly not be able to spot us in our current level of development. In a few millennium perhaps.
So we're looking for dumb aliens?
So, they're looking for civili[zs]ations classified as Type 3 in the Kardashev scale:
A civilization in possession of energy on the scale of its own galaxy.
OK, suppose we find their galaxy, conspicuous like a flamingo. How do we hail in order to confirm?
This post contains no rudeness or derision of any kind. All arguments are friendly. Terms and exclusions may apply.
This method has a difficulty. Most of the starlight from a galaxy comes from stars that will soon be gone. These are the luminous giant stars. But a big investment in a Dyson sphere would probably be made around a star more like our Sun which will stick around for a while. But even if most of the mass in stars is involved in this, it still won't get most of the light so long as it is the low luminosity stars that get the tech investment.
This is not a search for plants but rather Dyson Spheres. http://en.wikipedia.org/wiki/D...
Matthew 7:16: "By their farts shall ye know them"
Table-ized A.I.
Where life's emissions are easily detectable.
I'm not so sure I'd want to make contact.
I somewhat agree, but it could help tell us where to focus other search efforts.
And they are using such tech that we really can't see them, or know how they work, don't leave heat signatures, etc, I'm not sure this would be good for finding those Alien planets because chances are they got their shit together.
So it might be good to find other aliens who are as stupid as we are and don't mind polluting their planet and we love to pollute ours. I don't want to meet those people, chances are they are as fucked up as we are.
Of course, not saying we'd meet them as we are stupid and instead of spending money on science, we spend it on killing each other so a few people can make money.
Be seeing you...
Have any of our far flung space craft look back to our planet (and all the surrounding and background stuffs) snap a photo in the infrared spectrum ?
Yes. Quite a few satellites measure the Earth's IR emissions. Much of the sunlight that falls on the Earth is absorbed and re-emitted as IR. That is sort of the whole point of this search. An uninhabited star system will have only a very small fraction (maybe a billionth) of its light absorbed by planets and re-emitted as IR. But an inhabited star system, surrounded by a Dyson Sphere, will emit far more, or perhaps all, of it energy as IR. From what we understand about thermodynamics, this is impossible to avoid, so any civilization that uses energy on a solar or galactic scale should be detectable.
This sounds like a great way to discover alien civilizations too huge to give a shit about us, too far away to ever talk to.
Not that we should be picky, but this is punching above our weight.
i thought they would be looking for industrial gases in the spectrum from planets. It doesnt seem like streetlights and city lights would be significant compared to the amount emitted by suns.
It's a very simple, even lower-tech approach. Unstable molecules are unstable, stable ones aren't. Life isn't capable of producing stable molecules from stable molecules. Something, somewhere down the line, therefore must produce unstable molecules.
If you use spectrometry and find a planet that has two or more highly reactive molecules (especially if they cannot coexist naturally), that planet has complex life. If you have one reactive molecule that breaks down in sunlight but is being refreshed, that planet must have at least simple life. If the planet has highly reactive molecules that don't readily form naturally, you have life that is nominally intelligent.
No requirement for any technology capable of generating a specific signature. No requirement for the absence of metamaterials. No requirement for a telescope big enough to detect the signature against natural variation.
SKA would be capable of detecting an alien civilization using Lovelock's method anywhere inside of 1,000 light years, given the size and sensitivity currently being proposed. How big would the James Webb telescope need to be to get an IR signature on the industrialized part of the US at that range?
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
The complication is that even me, at 37C body temperature, I only radiate as much IR as is required to maintain this temperature. Similar arguments go for my car's body temperature and exhause temperature - where it is indeed huge. but life solved every process at low temperature that we have to use high temperatures for in industrial processes, so can an electric plus battery powered vehicle avoid thermal radiation issues that go much above the body temperature of the environment. Hotblooded living things like birds and mammals stick out of their environment as a heat signal, but the situation is much different with say snakes and bugs and fish. A planet full of snakes would be undetectable to have snakes based on infrared radiation measurements.
Also there might be a lot of life out there like Earth has been even 300 years ago, for 4 billion years, without giving off intelligent radio signals for instance, but we would not call them "intelligent" life forms. Even if they do have higher temperature processes, they may not be discernible on the scale of the caloric waterfall that happens from the 6000C temperature photons the Sun gives off, through the 0-30C environment on Earth, powering life, and emitted back as infradred of the average surface and atmospheric temperature of the Earth. You could not measure that there is life on Earth based on the excess infrared heat given off by the life present, and especially if all life were coldblooded snakes, bugs, fish and bacteria, plants, and the like. And they could still be intelligent even if cold blooded.
You could not measure that there is life on Earth based on the excess infrared heat given off by the life present
That is NOT what they are trying to do. The goal is not to detect planetary life. The goal is to detect Dyson Spheres, or other solar scale civilizations. A Dyson Sphere located at one AU will generate TWO BILLION times as much IR as the Earth.
Assuming that the civilization advanced enough to build a Dyson Sphere wasn't also advanced enough to recapture IR before it broadcast.
What if the advanced civilization turned out to be masters of power efficiency? An analogy from the world of computing: the first electronic computers required the power of a house simply to boot up. The smartphone in your pocket is thousands of times more powerful while using no more power than a small light bulb. Does this mean all we'll find are vacuum tube using spacefarers who use nuclear bombs for rocket fuel?
That is probably going to be the major problem, a Dyson sphere may just look like any other star. The waste heat will likely be some large percentage of the star's output, even with a Dyson sphere. What you'd probably get is an object radiating like a larger, dimmer version of the star inside it. If that is an unusual range of radiation for natural processes, you may be able to distinguish it. If it is close to the range for a natural red giant (for instance), we're out of luck.
That is covered with their parameter nu. From their table 1: "Power of other waste disposal (e.g. neutrino radiation, non-thermal emission, kinetic energy, energy-to-mass conversion)" so yes, there may be ways to reduce the signature.
suggests that the aliens might not abandon these stars just as the energy get is getting good. He may have a point there.
That is covered with their parameter nu. From their table 1: "Power of other waste disposal (e.g. neutrino radiation, non-thermal emission, kinetic energy, energy-to-mass conversion)" so yes, there may be ways to reduce the signature.
We do improve our energy efficiency. For example, combined cycle gas generators are 60% efficient, about twice a good as nuclear reactors. So, in the absence of cogen, 40% of the heat is discarded. But, so it the other 60%. Turning on a light heat the wall the light shines on..... So, it is 100% waste heat eventually. It is the 100% stuff (after use) that must be emitted to space and that is what the paper proposes to search for.