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Spot ET's Waste Heat For Chance To Find Alien Life

timothy posted about a month ago | from the especially-if-they've-got-grow-lights dept.

Space 80

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.

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I'm not saying it's aliens... (1)

Chuckstar (799005) | about a month ago | (#47738809)

obligatory picture of that crazy aliens guy goes here.

How bright is our own planet ... (0)

Anonymous Coward | about a month ago | (#47739493)

... in the infrared spectrum ?

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 ?

Re:How bright is our own planet ... (1)

ShanghaiBill (739463) | about a month ago | (#47739763)

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 [wikipedia.org] , 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.

Re:How bright is our own planet ... (1)

sillybilly (668960) | about a month ago | (#47740165)

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.

Re:How bright is our own planet ... (1)

ShanghaiBill (739463) | about a month ago | (#47740495)

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.

Re:How bright is our own planet ... (1)

Oligonicella (659917) | about a month ago | (#47740537)

Assuming that the civilization advanced enough to build a Dyson Sphere wasn't also advanced enough to recapture IR before it broadcast.

Re:How bright is our own planet ... (1)

mdsolar (1045926) | about a month ago | (#47741087)

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.

Re:How bright is our own planet ... (0)

Anonymous Coward | about a month ago | (#47742011)

The same dyson sphere would generate the same amount of energy regardless of it's distance from earth.

Re:I'm not saying it's aliens... (0)

Anonymous Coward | about a month ago | (#47739921)

This sort of process has been known to Sci-Fi for a long time now.. I recommend reading The Stars At War and The Shiva Option for examples of G-HAT/SETI gone horribly right and finding something horrible in general.

Re:I'm not saying it's aliens... (0)

Anonymous Coward | about a month ago | (#47740047)

We don't have pictures here at /. Next time, try to post something worth reading.

Re:I'm not saying it's aliens... (1)

captjc (453680) | about a month ago | (#47740137)

Since when is Slashdot a text mode version of Fark?

[Welcome To Slashdot]

\ I'm surfing on UltraSlashd+++CARRIER LOST+++

It'll be one of two things (1)

93 Escort Wagon (326346) | about a month ago | (#47738851)

Either we will have located the home world of the Quagaars, or it'll turn out to be a garbage pod.

Re:It'll be one of two things (0)

Anonymous Coward | about a month ago | (#47739021)

And watch out for the Zorgons.

Meaning... (0)

Anonymous Coward | about a month ago | (#47738857)

Even if we find an anamalous heat signature, we still can't be sure. Call me when you have a real SETI signal.

Re:Meaning... (1)

dreamchaser (49529) | about a month ago | (#47739491)

I somewhat agree, but it could help tell us where to focus other search efforts.

Low Tech? (1)

mdsolar (1045926) | about a month ago | (#47738871)

These are infrared array cameras mounted of space telescopes. How high tech do you want? http://wise.ssl.berkeley.edu/ [berkeley.edu]

Re:Low Tech? (0)

Anonymous Coward | about a month ago | (#47740547)

It's low tech compared to what some aliens are using.

Thermodynamics (1)

Myria (562655) | about a month ago | (#47738905)

The new approach, dubbed G-HAT for Glimpsing Heat from Alien Technologies, makes no assumptions about what alien civilisations may be like

Such assumptions as, that alien life has not found a way around the Second Law of Thermodynamics?

Re:Thermodynamics (0)

Anonymous Coward | about a month ago | (#47738955)

Unlikely.

Re:Thermodynamics (1)

bloodhawk (813939) | about a month ago | (#47740979)

perhaps overcoming the law of thermodynamics is unlikely. BUT, utilising the waste heat efficiently and effectively so that any such signature would be all but undetectable from this range I think would be distinctly possible, if not likely.

Re:Thermodynamics (1)

danlip (737336) | about a month ago | (#47738989)

That seems like a fairly safe assumption. On the other hand if they get all their power from solar (or wind, hydro, etc., which are just secondary affects of solar) then it seems to me they'd be in equilibrium and they'd have the exact same thermal signature as a no-civilization planet. That seems more likely.

That's no moon.... (1)

mdsolar (1045926) | about a month ago | (#47739279)

This is not a search for plants but rather Dyson Spheres. http://en.wikipedia.org/wiki/D... [wikipedia.org]

Re:That's no moon.... (1)

danlip (737336) | about a month ago | (#47739501)

Dyson Spheres are a rather silly thing to search for, as the technology required is too advanced to fathom (perhaps impossible). It seems the TFA was just talking about looking for aliens with huge power sources. That is certainly possible. But my point was that an advanced alien civilization may just have figured out how to be so efficient as to not need huge power sources. I was also responding to the "makes no assumptions about what alien civilizations may be like" statement in the summary, because it seems that they are making a pretty big assumption that could be easily violated without resorting to exotic materials or new laws of physics. We could even be there in 100 years.

Re:That's no moon.... (1)

mdsolar (1045926) | about a month ago | (#47739697)

They are usually putting gamma equal to alpha in the paper so Dyson spheres, cubes or pyramids is pretty much what they have in mind. http://arxiv.org/pdf/1408.1134... [arxiv.org]

Re:That's no moon.... (2)

khallow (566160) | about a month ago | (#47740563)

Dyson Spheres are a rather silly thing to search for, as the technology required is too advanced to fathom (perhaps impossible).

Let us recall that the Dyson sphere idea started life as a swarm of satellites around a star, not as a solid shell. I think I can fathom solar panels, satellites, and orbiting the Sun. That's the basics of a Dyson sphere (well, that and a relativistic traffic control problem which can involve at least as many satellites as there are people currently on Earth).

We could even be there in 100 years.

Indeed. Though it would probably involve self-replicating machines tearing apart Mercury.

Re: That's no moon.... (0)

Anonymous Coward | about a month ago | (#47740881)

Not even close. Dysons original paper calculated you would need the mass of Jupiter to make a sphere. As that's mostly gas, you would have to fuse it into carbon before you even start. Maybe at some point through the process of feeding a gas giant through a fusion reactor we might turn to actually conserving energy...

Re: That's no moon.... (1)

khallow (566160) | about a month ago | (#47741243)

Dysons original paper calculated you would need the mass of Jupiter to make a sphere.

I think Mercury is more than sufficient. We're just capturing the energy output of a star, you don't need a lot of mass for that.

Re:Thermodynamics (1)

TapeCutter (624760) | about a month ago | (#47739249)

How is the required ability to outshine said galaxy NOT a severe constraint?. The only thing this technique could possibly detect would be a Borg style alien civilization that has conquered and then overpopulated an entire galaxy, I'd say that puts a very tight constraint on the kind of aliens it can detect and a huge assumption that such galaxy wide civilizations are even possible in the first place. I think they should rename the project to A-HAT ( Aliens Harbouring Awesome Technology)

Re:Thermodynamics (0)

Anonymous Coward | about a month ago | (#47740179)

Hopefully they take the red shift into consideration. Radio astronomy is still where its at. A galaxy wide civilization has likely invented a FTL propulsion system which doesn't take the universe, or at least whole galaxy with it when launched. Detecting almost-stars is already difficult, detecting shielded and isolated "out-of-this-universe" or "constant-entropy" technology should be even more so.

Re:Thermodynamics (1)

tnk1 (899206) | about a month ago | (#47740791)

It does put a constraint on the aliens we can find, although it probably wouldn't need to be a galaxy spanning civilization. Outshining an entire galaxy enough to be detected individually can be done by a single star going supernova. While a Dyson Sphere or Swarm or other megastructures would probably not get to that level, they may emit their heat in a range that is very unusual for natural processes. If so, you filter out all light but that in the expected range and it becomes quite clear where those heat sources are.

Of course, even a single borderline Type II civilization would be an incredibly advanced civilization compared to us, but there could be a fair number of them out there, if such advances are possible. If anything, it would be a good thing to know.

Re:Thermodynamics (1)

Ol Olsoc (1175323) | about a month ago | (#47739573)

Such assumptions as, that alien life has not found a way around the Second Law of Thermodynamics?

Homer Simpson said it best:

https://www.youtube.com/watch?... [youtube.com]

Re:Thermodynamics (0)

Anonymous Coward | about a month ago | (#47741049)

This.

I mean, hell, look at that thing China and NASA just tested.
It seemingly contradicts one of these laws.

There was also some quantum entanglement experiments experimenting with, uh, whatever that "devil" was called again. Completely blank mind there.
Those came out with interesting results.

We also smashed the uncertainty principles apparent accuracy limits.

These are still very heavily theory, despite the law in the name.
We cannot even remotely state that something is a law of the universe when we occupy well under a quadrillionth of a percent of the universe.
Especially when it comes to the laws of thermodynamics, relativity (especially this), and even gravity. (which we still haven't figured out yet at all! We just know it exists and what more or less gives it value, not how it is mediated)

Of course, the second law is a fair bit better than the communication method.
Given an advanced civilization that was in space, given that spooky emDrive thing doesn't work, there'd most likely be quite a bit of heat being pumped out the back of a ship. Even in a theoretical warp engine.
For all we know, some civilization could be using neutrinos for communication.

False positives are far too easy (4, Interesting)

Dr. Spork (142693) | about a month ago | (#47738923)

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.

Re:False positives are far too easy (4, Informative)

mdsolar (1045926) | about a month ago | (#47739011)

It comes down to fig. 3 in their paper. http://arxiv.org/pdf/1408.1134... [arxiv.org] Natural source don't have the expected colors for waste heat from a solid surface. But that is the case when perhaps half the starlight in a galaxy is being used for power (their gamma=0.5). So, the civilization has to be pretty much like locusts for it the be easy to discern. There may be some civilization lifetime issues to worry about in that case.

Re:False positives are far too easy (2)

khallow (566160) | about a month ago | (#47739371)

So, the civilization has to be pretty much like locusts for it the be easy to discern. There may be some civilization lifetime issues to worry about in that case.

For them or for us?

Re:False positives are far too easy (1)

mdsolar (1045926) | about a month ago | (#47739429)

I was thinking them. Other galaxies are pretty far away.

Re:False positives are far too easy (1)

khallow (566160) | about a month ago | (#47739475)

If they've got half their galaxy colonized and they're "close" say within a few tens of millions of light-years to us, then they might already be colonizing our galaxy. My view is a few tens of millions of light years is not that much bigger a jump than a few tens of thousands of light years. For example, even if they didn't have a clue how to break down and store whatever components they use for their AU-scale system, they could always send a small star cluster over at a significant fraction of the speed of light.

Re:False positives are far too easy (1)

mdsolar (1045926) | about a month ago | (#47739677)

I suppose if you condensed the material in an AGN jet you get chunk of mass going that fast and reaching another galaxy. There are high velocity stars (not that high though) that might be three body interaction ejections from Andromeda http://www.technology.org/2013... [technology.org]

Is energy inefficiency a measure of progess? (2)

aNonnyMouseCowered (2693969) | about a month ago | (#47740799)

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?

Re:Is energy inefficiency a measure of progess? (2)

mdsolar (1045926) | about a month ago | (#47741621)

Energy used efficiently is still energy used. There is always waste heat. The paper addresses what would be an o[optimal waste heat temperature. http://arxiv.org/pdf/1408.1134... [arxiv.org] If you want your waste heat half as warm, your Dyson Sphere has to have four time the radius so you material use becomes excessive.

Re:Is energy inefficiency a measure of progess? (1)

aNonnyMouseCowered (2693969) | about a month ago | (#47741715)

"your Dyson Sphere"

I'd consider that inefficient. I mean there are far simpler ways of becoming a spacefaring species without hijacking an entire star. If an advanced civilization develops a method for "mind uploading" and downloading to an appropriate android or organic body, they'd only need to build a network of small space stations before they can "email" themselves from hub to hub at the speed of light, something that can well be powered by a small fusion reactor or some other energy source virtually undetectable from a light year away.

Re:Is energy inefficiency a measure of progess? (0)

Anonymous Coward | about a month ago | (#47745125)

a) There is nothing essential about "hijacking an entire star". The Dyson Sphere hypothesis merely postulates the possibility, not the desirability. If you decide to go "half Dyson" that's OK by me and likely Dyson too. Likely, you would build what you need, when you need it. There is no need to be at 100%.

b) "powered by a small fusion reactor or some other energy source virtually undetectable". First, waste heat is not undetectable. Second why would your hyperefficient overlords build a small fusion reactor when the universe provides galaxies with billions of large fusion reactors... FOR FUCKING FREE?!?!?!?!?!

c) When/if you put up a solar panel on your roof, that is your tiny contribution to a potential Dyson Sphere of solar arrays around our sun. You are also using fusion power which is cool too.

Re:Is energy inefficiency a measure of progess? (0)

Anonymous Coward | about a month ago | (#47746365)

a) There is nothing essential about "hijacking an entire star". The Dyson Sphere hypothesis merely postulates the possibility, not the desirability. If you decide to go "half Dyson" that's OK by me and likely Dyson too. Likely, you would build what you need, when you need it. There is no need to be at 100%.

You're right, Never go full Dyson. The rest of the universe will know who they are, the civilization playing the civilization disguised as another civilization!

Take the Vulcans for example, they were all smart and respectable, as soon as they started playing with red matter... now they are homeless...

Just look for their vacuums (0)

Anonymous Coward | about a month ago | (#47738939)

Aka Dyson Spheres - oh no they look just like red giants.

Re:Just look for their vacuums (1)

tnk1 (899206) | about a month ago | (#47740801)

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.

Spot the loonie (1)

turkeydance (1266624) | about a month ago | (#47738951)

with waste heat. never thought of that.

Far, far away (1)

Dorianny (1847922) | about a month ago | (#47738973)

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.

Re:Far, far away (0)

Anonymous Coward | about a month ago | (#47739353)

You clearly have no idea how far apart galaxies are.

Re:Far, far away (1)

Dorianny (1847922) | about a month ago | (#47739651)

You clearly have no idea how far apart galaxies are.

My comment says nothing about the time it takes our heat signature to reach beings in another galaxy observing ours, only that we currently we do not generate enough of it to be detectable.

Waste heat is inefficient (1)

Anonymous Coward | about a month ago | (#47738997)

So we're looking for dumb aliens?

Re:Waste heat is inefficient (1)

Tablizer (95088) | about a month ago | (#47739479)

Why not? The dumb ones may be easier to find. A crime analyst once told me he rarely finds smart crooks, but usually the dumb ones who leave obvious patterns. If they were smart, they'd probably be in a real profession instead of breaking into houses.

Similarly, aliens that don't want to be detected are probably not the ones we'd find first. It's the stupid ones that will stand out.

Re:Waste heat is inefficient (0)

Anonymous Coward | about a month ago | (#47746397)

What if the dumb aliens have really good lawyers? We might find them and never be able to prove it to James Woods, but the fact remains, we recorded 13 hours of static in .3 seconds of recording time. All the while the religious amongst us shrug it off and use "Wanna take a ride" (in a Matthew McConaughey drawl) as a bad pickup line in seedy space rangers bars and write novels about their lonely misery in crayon. They missed the point and that is what he said she said and all three are right!

Kardashev scale (3, Informative)

arielCo (995647) | about a month ago | (#47739143)

So, they're looking for civili[zs]ations classified as Type 3 in the Kardashev scale [wikipedia.org] :

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?

Re:Kardashev scale (2)

mdsolar (1045926) | about a month ago | (#47739167)

Would we want to? They sound like locusts.

Re:Kardashev scale (1)

Culture20 (968837) | about a month ago | (#47739239)

Locusts can taste pretty good if prepared correctly.

Re:Kardashev scale (1)

mdsolar (1045926) | about a month ago | (#47739381)

They can be assimilated?

Re:Kardashev scale (1)

tnk1 (899206) | about a month ago | (#47740815)

If they're Type III, they do the assimilating.

And yes, they think we are very tasty indeed. That's why their swarms are on their way and will be arriving in about 38,000 years.

Re:Kardashev scale (1)

Shinobi (19308) | about a month ago | (#47742371)

Don't forget that the genestealers arrive a fair bit earlier!

Re:Kardashev scale (1)

tnk1 (899206) | about a month ago | (#47740813)

A bunch of Type IIs would be sufficient for this, but certainly a Type III would be easier to find.

Problem (1)

mdsolar (1045926) | about a month ago | (#47739149)

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.

Re:Problem (1)

Velox_SwiftFox (57902) | about a month ago | (#47739461)

And of course, the more efficient the Dyson sphere, the less heat it radiates. At what temperature point would the law of diminishing returns have alien engineers say, "Ah, just radiate the rest of the energy to space, too much trouble to use it for anything more"?

Re:Problem (2)

mdsolar (1045926) | about a month ago | (#47739741)

Not really. The luminosity of a Dyson Sphere will be the same as the luminosity of the star it surrounds. The color temperature of the radiation will be lower by a factor of the square root of the ratio of the radius of the star to the radius of the sphere.

The author (1)

mdsolar (1045926) | about a month ago | (#47742189)

suggests that the aliens might not abandon these stars just as the energy get is getting good. He may have a point there.

Waste heat already discovered. (0)

Anonymous Coward | about a month ago | (#47739193)

No one will admit to the cause though.
http://m.youtube.com/watch?v=a... [youtube.com]

Close enough (1)

Tablizer (95088) | about a month ago | (#47739399)

Matthew 7:16: "By their farts shall ye know them"

The Burrito Galaxy (1)

statemachine (840641) | about a month ago | (#47739427)

Where life's emissions are easily detectable.

I'm not so sure I'd want to make contact.

If UFO's are real (1)

Nyder (754090) | about a month ago | (#47739519)

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.

Uhh, "new approach"? (0)

Anonymous Coward | about a month ago | (#47740007)

Heard about this idea AT LEAST 10yrs ago...new approach as in this is the first time that someone's actually implemented it, or...?

Not the kind of ETs we should be looking for (1)

goodmanj (234846) | about a month ago | (#47740017)

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.

What about looking for industrial gas (1)

Eravnrekaree (467752) | about a month ago | (#47740111)

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.

Meh. James Lovelock's idea is better. (2)

jd (1658) | about a month ago | (#47740113)

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?

Already done (0)

Anonymous Coward | about a month ago | (#47740725)

And it was found in New Mexico [archive.org] . :P

Old news (0)

Anonymous Coward | about a month ago | (#47740887)

Wasn't this on slashdot already about a month and change ago?

Low tech works best (0)

Anonymous Coward | about a month ago | (#47741529)

Everyone knows the best way to find ET is to lure them out with Reese's Pieces.

One Assumption (0)

Anonymous Coward | about a month ago | (#47741795)

There is an implicit assumption here - that ET is exothermic. What if waste heat is the "next big thing" after CO2 emissions in the development of civilization, and tech is discovered to conquer it?

Re:One Assumption (1)

mdsolar (1045926) | about a month ago | (#47742297)

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.

Why must they create waste heat? (0)

Anonymous Coward | about a month ago | (#47742153)

Why do we think an alien civilisation would not have solved the "Waste heat" issue?
If they are sufficiently technologically advanced shouldn't waste heat not be a prominent part of their society?
Aren't we constantly moving towards efficiency and reducing energy waste through heat and other reactions?

I find that much of the search for ET life seems rooted in a Universal view that is based solely on current human society and level of advancement.

Re:Why must they create waste heat? (1)

mdsolar (1045926) | about a month ago | (#47742335)

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.

What a stupid idea (0)

Anonymous Coward | about a month ago | (#47744467)

First of all, life isn't going to alter an entire galaxy's heat output by much, unless it's one HELL of a civilization. Second, so you find a slightly warmer galaxy. So what? What caused the extra warmth? There's nothing strongly indicative of life in such a finding.

What's important is how much warmer the galaxy is from it's output without life. Which is not a data point we can collect.

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