Beta

Slashdot: News for Nerds

×

Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!

Making It Hard For Extraterrestrials To Hear Us

timothy posted more than 4 years ago | from the sounds-like-a-fine-idea-to-me dept.

Communications 374

quaith writes "US astronomer Frank Drake has told scientists at a special SETI meeting in London that earthlings are making it less likely that we will be heard in space. In the past, we used huge ground stations to broadcast radio and television signals which could be picked up relatively easily — according to astronomers' calculations anyway. Now we use satellites that transmit at 75 watts and point toward Earth instead of into space. In addition, we've switched to digital which makes the transmissions even fainter. Drake has concluded that very soon, in space no one will hear us at all. I guess we'd better keep listening."

cancel ×

374 comments

Not news (5, Insightful)

l2718 (514756) | more than 4 years ago | (#30960196)

This issue was already known to Drake when he formulated his famous equation -- a key parameter is the time window during which a civilisation is broadcasting radio signals.

Re:Not news (2, Interesting)

Da Cheez (1069822) | more than 4 years ago | (#30960206)

Correct me if I'm wrong (I very well may be; I'm not overly familiar with the Drake equation), but doesn't that broadcasting time apply mainly to before a civilization has the technology to broadcast? What about when they still broadcast, but in such a way that their signals don't pollute deep space? Is that taken into account?

Re:Not news (4, Informative)

amRadioHed (463061) | more than 4 years ago | (#30960676)

The last factor in the equation is L, the length of time a civilization broadcasts radio waves into space.

Re:Not news (4, Informative)

amRadioHed (463061) | more than 4 years ago | (#30960702)

Reading the wikipedia page further, it seems like his understanding of L is that it represented how long a technological society would be capable of broadcasting into space. So it seems like he didn't actually consider that as technology advanced civilizations would significantly reduce the amount of stray emissions. As a result his guess for L was around 10000, a few orders of magnitude off it would seem.

Re:Not news (2, Insightful)

Supurcell (834022) | more than 4 years ago | (#30960248)

So even if we do happen to pick up radio signals from the 100 or so year window, during which aliens would be broadcasting radio waves, by the time we hear them, they could have been long extinct due to some catastrophe.

Re:Not news (2, Insightful)

Mashhaster (1396287) | more than 4 years ago | (#30960286)

This is why the Drake equation never did seem to make much sense to me.

Given the rapid advancement of telecommunications technology we've observed, to me it seems entirely possible that a civilization a few hundred or thousand years beyond ours might not even be using a technology analogous to RF transmission. Entanglement, gravitation manipulation, something entirely different?

We can only imagine, because who can say what discoveries the future will hold, but you can be damn sure that a thousand years from now we'll be using something different than we are now. The Drake equation always seem to me to require the presupposition that a far advanced extraterrestrial civilization would be using the equivalent of.. cosmic flag semaphore, or smoke signals.

Re:Not news (5, Funny)

pengin9 (1595865) | more than 4 years ago | (#30960424)

Yes xkcd [xkcd.com] says it best yet again.

Why can't we hear ET? (0)

Anonymous Coward | more than 4 years ago | (#30960298)

I keep asking this question: Why can't we detect ET's transmissions?

Now I know. They do digital as well.

Re:Why can't we hear ET? (5, Funny)

Toonol (1057698) | more than 4 years ago | (#30960322)

I keep asking this question: Why can't we detect ET's transmissions?

DRM'ed, no doubt.

Re:Why can't we hear ET? (4, Funny)

syousef (465911) | more than 4 years ago | (#30960672)

I keep asking this question: Why can't we detect ET's transmissions?

DRM'ed, no doubt.

Dude, if only that were true! You'd find aliens just by searching the pirate bay!

Re:Why can't we hear ET? (1)

starbugs (1670420) | more than 4 years ago | (#30960364)

I keep asking this question: Why can't we detect ET's transmissions?

Now I know. They do digital as well.

Not just that.

They've realized what we will also eventually realize.

They use cat6 cable.
Especially after we started sending all those damn microwaves into space and their wifi stopped responding.

Re:Not news (2, Interesting)

BryanL (93656) | more than 4 years ago | (#30960338)

Yes, but the assumption was that civilizations stopped broadcasting into space because they ceased to exist. Now we can think, maybe there are civilizations out there that are extant, but past the point of radio broadcasts. This is good news if we hope that intelligent life is still out there.

Re:Not news (1)

l2718 (514756) | more than 4 years ago | (#30960358)

Yes, but the assumption was that civilizations stopped broadcasting into space because they ceased to exist.

Was it really? It doesn't sound credible to assume that ET civilisations would transmit strong radio signals throughout their existence. The question always was about the time period between discovery of radio and the transition to a more advanced technology.

Re:Not news (2, Interesting)

amRadioHed (463061) | more than 4 years ago | (#30960710)

His guess was that the broadcasts would last for 10,000 years. So yeah, he was thinking the radio emissions would last as long as the civilization was capable of producing them.

Re:Not news (1)

AmigaMMC (1103025) | more than 4 years ago | (#30960380)

Good! Less Covenant ships to worry about

1UP Drake's 7 (-1, Troll)

fibrewire (1132953) | more than 4 years ago | (#30960388)

Mick Jagger said it best - "Fuck 'em if they can't take a joke."

All that funding for so many years just to realize it was all a waste. How about we sell SETI to fund a real space program? Like one to bring back some stupid moon rocks? American moon rocks - or better yet i'll take that money and spend it on a robotic whore. http://www.youtube.com/watch?v=091ugdiojEM [youtube.com]

I swear this country gets closer to "Idiocracy" every year...

Sufficiently Advanced (4, Insightful)

Da Cheez (1069822) | more than 4 years ago | (#30960198)

So if a sufficiently advanced civilization (like ours) eventually develops radio technology that doesn't get far beyond their own planet, could this severely limit how much we would detect from other planets in the way of radio signals?

Re:Sufficiently Advanced (1)

LifesABeach (234436) | more than 4 years ago | (#30960326)

I'm sorry, I didn't hear you, could you say that again?

Re:Sufficiently Advanced (1)

nicc777 (614519) | more than 4 years ago | (#30960656)

That was exactly my first thought as well.

This has its perks (5, Insightful)

mysidia (191772) | more than 4 years ago | (#30960204)

It reduces the probability that earth could be quickly located.

We gotta consider the possibility, that any extraterrestrials close enough to hear our signals in any reasonable amount of time, and with the sophistication to pinpoint us....

Might have the technology and desire to invade earth.

E.g. Consider earth itself... fast forward a few dozen generations...... massive overpopulation, lack of resources, land, severe overcrowding.

Extreme desire for another habitable place to live.

And then you detect an alien signal.. a foreign world. You step foot there, and you're greeted by basically an aboriginal species (compared to your civilization).

Habitable world, massive resources, very primitive 21st-century level technology, nothing compared to your 23rd century tech.

Oh.... so some colonists start travelling from earth to 'the new world' for a better life.

Settlers VS the Natives all over again.

It's happened before, it could happen again. Except us earth inhabitants could be the primitive natives / "Indians" / etc.

Scary, huh? :)

Re:This has its perks (3, Funny)

nitro316 (1179211) | more than 4 years ago | (#30960222)

James Cameron? Is that you?

Re:This has its perks (2, Informative)

grouchomarxist (127479) | more than 4 years ago | (#30960254)

It would be easier for us to inhabit the Moon or Mars or the oceans or underground or where ever than to go to a new solar system. I imagine that by the time a civilization has the power to go to another solar system for colonization issues of overcrowding would be overcome by technology. If they can get here they'll probably either come for research or just to fuck with us.

Re:This has its perks (1)

mysidia (191772) | more than 4 years ago | (#30960336)

The trouble with the moon or mars, is they don't have a breathable atmosphere: it would be dangerous to live there (due to no electromagnetic field or protections against cosmic rays, rocks hitting the planet, etc), and they are not very habitable worlds.

It's conceivable people could try to live there, but there would almost certainly be more volunteers to go live in a slightly less-hostile environment.

I wouldn't assume (so readily) that extraterrestrials are necessarily outside the solar system. Even the solar system is a big place, and there may be some habitable moon unaccounted for.

I also wouldn't assume their navigational capabilities or ease of travelling from another system are as poor as ours.

They may have some mode of transporation that enables them to accomplish with ease, what would be impossible for current human tech.

I have my doubts that technology is able to negate overcrowding issues.

When you run out of space on your planet, you run out of space. It's unlikely that even advanced technology would allow extraterrestrials to construct new planets or make worlds with no usable atmosphere habitable.

Underground living might be possible, but even that has certain feasibility limits.

Re:This has its perks (1)

grouchomarxist (127479) | more than 4 years ago | (#30960512)

Interstellar space is even more inhospitable than the moon or Mars. If you've developed technology where you can live in tin can for extended periods of time and travel light years across the galaxy, then living on a place like the moon or Mars is relatively easy.

Once we develop such a technology the only need is to collect raw materials. There isn't really a need to settle on a planet because the spaceship would be a more hospitable place than any alien world.

Re:This has its perks (2, Interesting)

mysidia (191772) | more than 4 years ago | (#30960624)

I'm presuming the extraterrestrials have developed technology to travel between galaxies in a few months or less.

I wouldn't expect a space ship to be usable as a comfortable living environment for extended periods of time.

Re:This has its perks (1)

Supurcell (834022) | more than 4 years ago | (#30960668)

Unless every room was a holodeck.

Re:This has its perks (4, Insightful)

cetialphav (246516) | more than 4 years ago | (#30960368)

I imagine that by the time a civilization has the power to go to another solar system for colonization issues of overcrowding would be overcome by technology.

I'm sure the Native Americans that occupied North America would have thought that about the Europeans, too.

It is really hard to make any assumptions about why aliens might show up on our doorstep. There are logical explanations for why a peaceful, curious society would make the journey, but there are equally logical explanations for a hostile society. Certainly, the ability to develop long distance space travel means that a society has a high level of organization and cooperation. But we have seen that here on earth with both the United States and Nazi Germany. We also know that military conflict can be a great motivator to developing some kinds of technology, so visitors to earth might arrive in warships.

The bottom line is we just don't know and no explanation seems any more plausible than any others.

Re:This has its perks (1)

BronsCon (927697) | more than 4 years ago | (#30960716)

If they can get here they'll probably either come for research or just to fuck with us.

So, you're saying we're either Wikipedia or /b/?

Re:This has its perks (0)

Anonymous Coward | more than 4 years ago | (#30960290)

Yes, that was a very scary proposition, back in the 19th century when that was an original idea. Its the fucking 21st century mother fucka! Recognize!

Re:This has its perks (1, Interesting)

Anonymous Coward | more than 4 years ago | (#30960296)

Any civilization advanced enough to send an invasion force would most likely have the technology to resolve the contents of the earths atmosphere from great distances. Being scared of invasion does not buy much.

Re:This has its perks (5, Interesting)

Jeremi (14640) | more than 4 years ago | (#30960312)

[Aliens] might have the technology and desire to invade earth.

Not if they have any economic sense in their heads. Unless the aliens have some sort of magic infinite energy source or teleportation device, the cost of transporting an invasion fleet to another solar system would be orders of magnitude higher than the value of anything they could possibly gain from Earth. And if they do have an infinite energy source or teleportation device, then they could use those inventions to provide for their needs directly, without leaving their home.

So if aliens invade, it will be for solely their own entertainment, not for economic reasons.

Re:This has its perks (2, Funny)

eclectro (227083) | more than 4 years ago | (#30960434)

So if aliens invade, it will be for solely their own entertainment, not for economic reasons.

Unless they invade so they can suck our brains with a straw. Which case that would be for both entertainment and economic reasons.

Re:This has its perks (1)

91degrees (207121) | more than 4 years ago | (#30960454)

Not if they have any economic sense in their heads. Unless the aliens have some sort of magic infinite energy source or teleportation device,

Well, magic isn't totally out of the question - any sufficiently advanced technology will be indistinguishable from magic, and any technology distinguishable from magic is insufficiently advanced.

could be sexual reasons (2, Interesting)

r00t (33219) | more than 4 years ago | (#30960462)

If you're an alien dude who wants to score with the alien chicks, you might just impress them by collecting humans. You could embed a human in a chunk of pure carbon-12 diamond, mount that in an iridium ring, and slip it onto her tentacle. She might have thousands of tentacles.

Maybe you collect humans to sell as an aphrodesiac. You puts the heads on top of a snack, kind of like sea urchin eggs on sushi.

Maybe you lay eggs in the humans. Ever see that movie with the pods? The aliens take over human bodies. An infected human passionately embraces an uninfected human, and then the alien penis-thing (an ovipositer maybe?) bursts out of the infected person's forehead and stabs right into the uninfected person's forehead.

Maybe you even mate with the humans. You keep them in your flying saucer and rape them with **all** your tentacles in every oriface. When the alien babies are ready to be born, the humans explode.

Re:could be sexual reasons (2, Insightful)

Supurcell (834022) | more than 4 years ago | (#30960674)

It sure would suck for an alien species to evolve to have to come all the way out to earth and use humans as part of their reproductive cycle.

Re:This has its perks (1)

bhartman34 (886109) | more than 4 years ago | (#30960532)

Unless the aliens have some sort of magic infinite energy source or teleportation device, the cost of transporting an invasion fleet to another solar system would be orders of magnitude higher than the value of anything they could possibly gain from Earth.

Doesn't that assume minimal technological progress? It could be that the cost of transporting an invasion fleet great distances could be much less for a sufficiently advanced civilization. Technology has a way of becoming cheaper over time.

I kind of agree with your general conclusion, though: If we do get invaded, it will probably be for entertainment purposes. The distance between us and the prospective invaders is almost certainly sufficient that they could acquire whatever they needed from a more local planet (unless there's some unique property to human beings that they need -- but I sincerely doubt that, given the fact that the elements in our bodies seem to be readily available elsewhere in the universe).

Re:This has its perks (1)

timmarhy (659436) | more than 4 years ago | (#30960556)

you haven't thought this out. energy isn't the only resource they might require (too much peak oil bunk you've been reading i suspect). a habitable planet is worth a lot more then just energy. even a huge energy source is useless if you don't have air to breath.

Re:This has its perks (2, Interesting)

Exception Duck (1524809) | more than 4 years ago | (#30960708)

maybe they wouldn't need a big fleet.

just one virus

or nanobots - grey goo us all...

to stop the pink goo*

*: Pink Goo is mankind. It replicates relatively slowly, but some people think it will nevertheless fill any amount of space given enough time. In the pink goo worldview the spread of humanity is a catastrophe and space exploration opens up the possibility of the entire galaxy or the universe getting filled up with Pink Goo - the ultimate crime, something to be stopped at any cost.

Re:This has its perks (1)

pydev (1683904) | more than 4 years ago | (#30960712)

So if aliens invade, it will be for solely their own entertainment, not for economic reasons.

You're thinking "Mars Attacks". But an invasion might consist of a bit of nanotechnology together with some retroviruses and parasites. That's possibly only a gram of payload.

Re:This has its perks (2, Insightful)

j_sp_r (656354) | more than 4 years ago | (#30960718)

Maybe they need "Lebensraum", because there are not many planets that sustain life?

Good. (1)

k.a.f. (168896) | more than 4 years ago | (#30960224)

The possibility of extra-terrestrials intercepting our signals, being interested in them, replying before humanity has run its course, and something good coming of it, are so remote that it's not worth constantly wasting energy for the purpose. If you look at Earth from space you realize what a tiny, limited, fragile place it is and how important it is that we do all we can to make us "live long and prosper". Hoping that aliens are going to help us in any way is counter-productive.

Re:Good. (3, Insightful)

cetialphav (246516) | more than 4 years ago | (#30960428)

The flip side, of course, is that monitoring for radio signals is extremely cheap. It uses equipment that we already use for other purposes and a small number of researchers. The potential upside is huge, though. Discovering that an advanced civilization exists somewhere is such a big deal that there is no reason not to do something cheap and easy to find it.

I agree that the odds are stacked against us and that it is unlikely that we find anything. Even if we are lucky enough to pick up a signal, establishing communications would be difficult. The odds are stacked against us, no question. But we are a curious species and we just can't pass up an opportunity to learn something, especially when it costs us so little.

Fermi Paradox (4, Interesting)

localman (111171) | more than 4 years ago | (#30960226)

And this is a possible answer to the Fermi paradox. Well, after you accept that interstellar travel is not economically feasible.

Broadcast is not a great communication strategy. On-demand point-to-point communication takes over most things. Advanced civilizations go silent from the outside within a blink of them transmitting their first broadcast signals. There's no reason to think that we'll ever put serious effort into sending signals into the black given all the other things on our plate. And there's no reason to think that any other civilization would have such extra resources either.

Cheers.

Re:Fermi Paradox (1)

Jeremi (14640) | more than 4 years ago | (#30960268)

There's no reason to think that we'll ever put serious effort into sending signals into the black given all the other things on our plate. And there's no reason to think that any other civilization would have such extra resources either.

Sure there is... it's not like putting up a few beacons is hard to do, as evidenced by the fact that we were able to do it, unintentionally, even back in the 1920's.

Whether or not we (or any hypothetical aliens) would want to do it is another question, but certainly any technological civilization equal to or more advanced than our can do it, with very little effort. Hell, a sufficiently motivated private citizen could do it (FCC regulations notwithstanding).

Re:Fermi Paradox (3, Interesting)

0123456 (636235) | more than 4 years ago | (#30960280)

And this is a possible answer to the Fermi paradox. Well, after you accept that interstellar travel is not economically feasible.

Except no-one in their right mind would accept that. The cost of an interstellar colonisation flight would be small compared to the value of another solar system, and the cost of not expanding to other solar systems would be the death of our species.

Given that any alien race who chose to expand could colonise the entire galaxy in under ten million years without even trying hard (or a hundred million years without trying at all, just by tourists on a random walk), the answer to the Fermi Paradox is simple: there aren't any... if they existed, they'd be about as hard to spot as technological life in Manhattan.

Re:Fermi Paradox (3, Interesting)

Bartab (233395) | more than 4 years ago | (#30960440)

Except no-one in their right mind would accept that. The cost of an interstellar colonisation flight would be small compared to the value of another solar system, and the cost of not expanding to other solar systems would be the death of our species.

The economic return of interstellar colonization is zero.

The only return is darwinistic. Not all our eggs in one biological basket, and all that. However, unless we're damn sure the target system has an earth-like breathable, survivable biosphere, then we may as well stick to this system. We're not exploiting most of it at all. We -might- find an oxygen atmosphere, heated water laden, near-1g planet "nearby" (100 ly) but it's unlikely. What's nearly impossible is finding one with a biosphere that we can survive in without basically obliterating it and dropping down earth biologicals. Most things on such a planet would poison us.

Unless such a magical planet is found, exploring outside our system before serious colonization (which -could- be economically valuable) of Mars, gas giant moons, etc is a waste. On all levels.

If such a planet was found, I'd consider it proof of god.

Re:Fermi Paradox (3, Interesting)

bit01 (644603) | more than 4 years ago | (#30960706)

The economic return of interstellar colonization is zero.

The economic return of life is zero. Pretty pointless expending all that energy to be worm food.

You need to remember what economic value is - anything that people value and are willing to pay money for.

And a lot of people think that extending humanity's reach is pretty damn valuable. You might not agree but different people have different values.

---

DRM'ed content breaks the copyright bargain, the first sale doctrine and fair use provisions. It should not be possible to copyright DRM'ed content.

Re:Fermi Paradox (2, Insightful)

precariousgray (1663153) | more than 4 years ago | (#30960334)

And there's no reason to think that any other civilization would have such extra resources either.

I think it's a pretty ignorant statement to presuppose that any other civilization in the universe will necessarily irreparably rape and exploit their planet for resources as badly as we humans have.

This is good... (4, Insightful)

VendettaMF (629699) | more than 4 years ago | (#30960228)

This is good news. And overdue.

We've been a stupidly noisy duck for far too long.

so what (3, Insightful)

Punto (100573) | more than 4 years ago | (#30960232)

the closest aliens are at least thousands of light years away, they haven't "missed" our radio signals, they still haven't heard them yet. And they'll have like 100 years of signals to figure us out.

Re:so what (3, Funny)

Supurcell (834022) | more than 4 years ago | (#30960682)

And when they do see those signals, they will shit themselves when they see how good we are at killing aliens and promptly call us up to surrender.

perhaps (3, Insightful)

wizardforce (1005805) | more than 4 years ago | (#30960236)

Considering how the meeting between two civilizations, one more avanced than the other has generally gone badly for the majority of human history, it may not be such a bad idea to keep ourselves quiet until their intentions are shown to be peaceful/cooperative.

Light pollution (1)

ickleberry (864871) | more than 4 years ago | (#30960242)

Since we still pump large amounts of light into space from street-lighting around the world would that not be easier to detect than a few encoded radio signals?

Even if they detect a digital signal they still have to demodulate it to this obscure 'base-2' encoding we use over here because it works well with our equipment they have either grown out of or never discovered, after that they might decide to visit asciitable dot com [asciitable.com] to find out what it actually means.

Maybe we can buy out Arecibo and continuously waste a few megawatts at broadcasting a "Hello?! Can you hear me now?" analogue recording

Re:Light pollution (1)

l2718 (514756) | more than 4 years ago | (#30960318)

This "light pollution" is completely negligible. First of all it is entirely negligible compared with the sunlight reflected from Earth. Secondly, the sun is orders of magnitude brighter. Seeing a small planet that close to the sun is nearly impossible. Adding 0.001% [number made up by me] to the planet's luminosity won't make a difference.

Re:Light pollution (1)

wizardforce (1005805) | more than 4 years ago | (#30960412)

How many orders of magnitude more visible light do we emit than radio waves? In about 20 years we'll have the technology to directly image an extrasolar planet on a fairly consistent basis. Not long after that, we'll probably be able to detect artifical lights on the surface of an extrasolar planet on its night side. This is probably far easier than trying to fish out their extremely diluted, planet directed signals.

Re:Light pollution (1)

l2718 (514756) | more than 4 years ago | (#30960524)

I think the signal-to-noise ratio matters more than the luminosity here. The signal due to "artifical lights on the surface of an extrasolar planet on its night side" will surely be swamped by simple fluctuations in the output of the star. IANAAstrophysicist but my guess is that the radio background from the sun is far weaker than the visible light background .

Re:Light pollution (1)

Ambiguous Puzuma (1134017) | more than 4 years ago | (#30960530)

In about 20 years we'll have the technology to directly image an extrasolar planet on a fairly consistent basis.

Will we? Images of Pluto are still pretty underwhelming. It may be small and poorly lit, but it's a heck of a lot closer to us than any exoplanet.

Re:Light pollution (0)

Anonymous Coward | more than 4 years ago | (#30960558)

How many orders of magnitude more visible light do we emit than radio waves?

The visible light we emit is negligble compared to radio waves. Think for instance of a cruise ship at sea (I'm into sailing so this is the analogy that hit me immediately). In order to hear its 25 W VHF radio the ship must be visible and even on a clear night and when such a ship is close enough for at least half the decks still be theoretically visible above the horizon, the lights from thousands of cabins, lanterns, nightclubs etc. do not make it visible but its radio transmissions are crystal clear. 25 W radio vs. thousands of lights that are at least 25 W each!

In about 20 years we'll have the technology to directly image an extrasolar planet on a fairly consistent basis. Not long after that, we'll probably be able to detect artifical lights on the surface of an extrasolar planet on its night side. This is probably far easier than trying to fish out their extremely diluted, planet directed signals.

If a civilization out there currently inhabits a planet so that they actually do emit more artificial light than radio waves, they'll probably discover radio before we develop any technology to detect artificial light from the surface so it's a safer bet to keep improving SETI@home and others instead. Besides, radio signals aren't directed.

it's modulated (5, Interesting)

r00t (33219) | more than 4 years ago | (#30960500)

We have large synchronized power grids. They'll get a signal that's 2x the line frequency. As the Earth turns, you get modulation of various sorts: frequency, phase, amplitude.

Amplitude goes down for oceans, and up for land. You get more 100 Hz for the Old World, and more 120 Hz for the New World. As different country-sized areas with the same line frequency pass into view, you get phase change.

It all has a nicely repetitive 24-hour period.

Re:Light pollution (0)

Anonymous Coward | more than 4 years ago | (#30960568)

Since we still pump large amounts of light into space from street-lighting around the world would that not be easier to detect than a few encoded radio signals?

Zcjribaz: Hey, 'rup, I got a solar system with a planet whose absorption spectrum, relative to its sun, shows tons of free diatomic oxygen in its atmosphere. Gotta be life there. Otherwise the oxygen would react with all the other crap on the surface and precipitate out as rust, right?
Freljrup: Zude, look at the emission lines. I don't know what kind of chemistry's going on up there to produce the free oxygen, but faint as it is, it's proof that it's also vaporizing sodium. Anything based on carbon would have been incinerated.

If they're watching for the planet's transit of the star, they can only see the night side of the planet. The ring of atmosphere absorbs some of the Sun's light, and they see that we have oxygen, but they're always looking at the night side of Earth, so the streetlights are always on.

If they're watching us from above (or below) the plane of the ecliptic, they get a mix of absorption (sunlight filtered through the atmosphere, reflected from the planet's surface, and bounced through the atmosphere again before it hits their telescopes) and emission (sodium vapor streetlamps on the night side of the planet) spectra.

myopic (1)

quantumpineal (1724214) | more than 4 years ago | (#30960250)

If any alien civilization were capable of communicating or visiting here, I doubt these issues will be a problem?

Re:myopic (1)

Fujisawa Sensei (207127) | more than 4 years ago | (#30960376)

If any alien civilization were capable of communicating or visiting here, I doubt these issues will be a problem?

If they were sane, they would put up a big sign outside our solar system saying: stay away from these assholes.

Only if you were over optimistic (1)

Asadullah Ahmad (1608869) | more than 4 years ago | (#30960256)

This might have been true if were being really optimistic and assuming that there was Intelligent life within 100 LY of our solar system.

I really hope and speculate that whatever Extraterrestrials might be trying to listen to us, or someone else for that matter, they will be using something a bit more advanced that our latest technology and form of communication.

Correct me if I'm wrong... (2, Informative)

AnotherUsername (966110) | more than 4 years ago | (#30960264)

I was under the impression that historically, our radio and tv signals didn't even make it to Alpha Centauri. Unless we suddenly discover extra-terrestrial life inside of our solar system, does the switch to digital really change anything? Correct me if I am wrong, please.

OMG! Haven't anyone watched the X-Files! (1)

creimer (824291) | more than 4 years ago | (#30960266)

Considering that most aliens are hellbent to destroy Earth (according to a reliable media source in Hollywood), maybe going silent would be a good idea?

More to the point (3, Insightful)

Dunbal (464142) | more than 4 years ago | (#30960272)

Do we WANT to be detected? Oh it would be wonderful if we could communicate with intelligent life somewhere other than earth (I am assuming there is intelligence here). But what if the species we contact are not peaceful? What if they're out looking for worlds to enslave? There certainly would be an advantage in staying quiet and being the first to "discover" a new civilization without giving up our own presence. That way we could study these new beings before deciding whether to risk contact or not.

Likewise, the same logic can be applied to an alien species. Why would they trust us? Why would they carelessly beam their presence out into space, not knowing who was going to listen in? It is certain, given our past history (you know, that part about strong humans usually ending up wiping out weaker ones through conquest), that we ourselves aren't exactly trust-worthy. Maybe they have heard us, and we failed the test, and we will never meet our neighbors. That is one possibility the "Drake Equation" fails to account for. Maybe we will be permanently assigned to the universe's "time out" box, because of our bad behavior - and we'll never know.

Re:More to the point (2, Interesting)

bhartman34 (886109) | more than 4 years ago | (#30960636)

That is one possibility the "Drake Equation" fails to account for.

There's a lot the Drake Equation fails to account for. As a mathematical estimate, it's fairly useless. Its chief contribution to science (although some might question whether this is a contribution) is that it gets people talking about extraterrestrial life.

Find US? (5, Insightful)

Rammed Earth (1732102) | more than 4 years ago | (#30960276)

Has anyone considered the historical evidence of what happens when superior civilizations encounter lesser ones? The Native Americans, the Mayans, the Incas, the Australian Aborigines, the tribes of South America, the natives of Pacific Islands, to name a few, all cry out to humanity to avoid at all costs encounters of the first, second, and third kinds. We have no reason to expect anything but annihilation from advanced alien races- either they are truculent and violent like we are, or they will destroy us as a service to the rest of the galaxy. We do not wants aliens to find us!

Re:Find US? (1)

dspratomo (264659) | more than 4 years ago | (#30960554)

However do we wants to find aliens? (after watching avatar movie, and reading your thread, I'm pretty sure yes we do)

Re:Find US? (1)

dtml-try MyNick (453562) | more than 4 years ago | (#30960560)

Has anyone considered the historical evidence of what happens when superior civilizations encounter lesser ones?
Has anyone considered the historical evidence of what happens when human civilizations who feel superior encounter ones they consider lesser?
The Native Americans, the Mayans, the Incas, the Australian Aborigines, the tribes of South America, the natives of Pacific Islands, to name a few, all cry out to humanity to avoid at all costs encounters of the first, second, and third kinds.
We are so ignorant and arrogant that we expect other civilizations to think and act exactly like us (which led to the above in the first place) so they must be truculent and violent like we are, and they will destroy us as a service to the rest of the galaxy because that is what we would do. Let's just hope aliens don't find, or if they do, avoid us.

 

Re:Find US? (0)

Anonymous Coward | more than 4 years ago | (#30960574)

Those where technologically inferior civilizations in other aspects we may have been and quite possibly still are inferior.

Re:Find US? (3, Insightful)

syousef (465911) | more than 4 years ago | (#30960678)

Has anyone considered the historical evidence of what happens when superior civilizations encounter lesser ones? The Native Americans, the Mayans, the Incas, the Australian Aborigines, the tribes of South America, the natives of Pacific Islands, to name a few, all cry out to humanity to avoid at all costs encounters of the first, second, and third kinds. We have no reason to expect anything but annihilation from advanced alien races- either they are truculent and violent like we are, or they will destroy us as a service to the rest of the galaxy. We do not wants aliens to find us!

Not a problem, unless they're very long lived or really have found a faster than light travel mechanism. Civilizations that were conquered on earth were all reachable well inside a human lifetime. What's more the civilizations all had things of value to the invaders - land, resources, natives to indoctrinate in their religion. Any civilization sufficiently advanced to invade would likely be able to obtain their resources more locally, and colonise more local uninhabited worlds. I would hope they're past superstition, but who knows.

Serves those aliens right (1)

Arancaytar (966377) | more than 4 years ago | (#30960282)

I guess they should have paid their TV bill.

Woot alien 50s (0)

Anonymous Coward | more than 4 years ago | (#30960292)

So all we'll from aliens is their equivalent to 50s sitcoms and Grand Ole Opry.

Is SETI hopeless? (1)

bob5972 (693297) | more than 4 years ago | (#30960300)

So if the trend of our communications technology is to become less noticeable to space people, and we assume aliens follow a similar course of technological development, does SETI have any hope of finding anything?

Re:Is SETI hopeless? (1)

l2718 (514756) | more than 4 years ago | (#30960384)

This depends on whether we decide to continue to send radio signals to space deliberately even after we don't need to do it incidentally.

so advanced civilizations only use radio..... (0)

Anonymous Coward | more than 4 years ago | (#30960330)

So what makes anyone think if there are any other advanced civilizations out there that they are still using radio so we can hear them and not digital. Oh I forgot only we can think of such great technology.....all aliens if any are stupid monkeys hanging from trees.

Brandon (0)

Anonymous Coward | more than 4 years ago | (#30960332)

Good, now we don't have to worry about our world being conquered and our resources being devoured by an extraterrestrial race that heard us a couple galaxies over.

Don't forget "Active SETI" (4, Interesting)

l2718 (514756) | more than 4 years ago | (#30960346)

There have been several attempts [wikipedia.org] at sending radio messages into space specifically for communication purposes. Whether we keep that up or not is independent of our use of radio for intraplanentary communications.

WRONG! (0)

Anonymous Coward | more than 4 years ago | (#30960348)

I just love those who specialize, they have no concept of things out of their field, like say, broadcast Television, AM and Shortwave Radio which emit thousands of watts of rf into the universe 24/7/365.

We can only hope it's Vulcans that find us (1)

mykos (1627575) | more than 4 years ago | (#30960350)

Would pretty much suck if it were Vogons.

Why? (2, Insightful)

Tibia1 (1615959) | more than 4 years ago | (#30960392)

Why are so worried about finding aliens right now? Its like a child trying to throw a paper plane to the top of a mountain. We need better technology and it will be here soon. Best not worry where we're pointing our signals at the moment.

Maybe this is a good thing? (2, Funny)

martin-boundary (547041) | more than 4 years ago | (#30960398)

In nature, young defenceless animals which make too much noise and bring attention to themselves often get invited to dinner by predators. Discuss.

What's a few orders of magitude out of trillions? (1)

jandrese (485) | more than 4 years ago | (#30960442)

The freespace loss from Earth to anywhere outside of the solar system is so incredible that fretting over a couple hundred dB out of literally trillions seems ridiculous, especially with the enormous noise source of the sun practically on top of us (in a galactic sense).

I've always thought the idea that an ET would detect our Radio/TV signals to be romantic at best. This is also why SETI is pretty much pointless.

Re:What's a few orders of magitude out of trillion (1)

jessica_alba (1234100) | more than 4 years ago | (#30960666)

lasers could easily out shine the sun

ping. ping: you'r pwned! (0)

Anonymous Coward | more than 4 years ago | (#30960448)

loudest noises we make into space are radar-type pings to gauge distances of asteroids, etc.

who makes those pings?

astronomers!

please guys, just cut the noise before the aliens come and make us stop.

Not all signals are communications (1)

Beryllium Sphere(tm) (193358) | more than 4 years ago | (#30960452)

Military over-the-horizon radars put out a lot of power.

Re:Not all signals are communications (1)

OrangeTide (124937) | more than 4 years ago | (#30960476)

We'll likely stop using those as well as better technology comes about, or if some senators get convinced that it harms bats/birds/whales/aardvarks/etc.

Re:Not all signals are communications (1)

MichaelSmith (789609) | more than 4 years ago | (#30960548)

Just enough to make someone elsewhere say Wow! [wikipedia.org] , but no more than that because they won't hear it again.

This is not the pun you're looking for. (1)

fenix849 (1009013) | more than 4 years ago | (#30960478)

I can't beleive i'm the first person to think of/post this, but:
In space, nobody can hear you stream.

Ignores other sources (1, Insightful)

bertok (226922) | more than 4 years ago | (#30960484)

I can't believe this came from educated scientists.

Our communications signals are getting weaker, sure, but we still have other sources of clearly artificial radiation that are just as powerful as before. For example, military and weather radar. We regularly send out radar pusles powerful enough to compute the range to other planets in the solar system. Similarly, the Deep Space Network sends out powerful signals on various frequencies using highly directional beams when communicating with space probes.

Radio, that's so last millenium... (1)

meerling (1487879) | more than 4 years ago | (#30960486)

To think that aliens will be using radio is like Geronimo thinking the people in Europe used smoke signals.

Wish I could tell you what they are using, but as we haven't invented or noticed it yet, your guess is as good as mine.
(For my guess I'll say they're using Quantum Filament Transmission Sequencers. Whatever that is.)

I don't begrudge the idea of searching for alien radio signals, we might luck out and find one and actually recognize it for what it is, but I'm not holding my breath.
(Besides, foreign art film reruns are bad enough, do you really want to see alien ones?)

That's what's wrong with SETI (5, Interesting)

Animats (122034) | more than 4 years ago | (#30960492)

I've been critical of SETI efforts for this reason. Much SETI effort was focused on looking for "carriers", big constant-frequency RF sources. Broadcast AM, FM, and analog TV (which was AM video, FM audio) have strong carriers, but that was hugely inefficient. About 80% of an analog TV station's power output wasn't conveying any information other than "We're here". As receivers improved, new RF technologies used weaker carriers, then suppressed carriers, and finally, with spread spectrum, dropped the whole concept of carriers. Many modern RF signals appear to be noise unless you understand the encoding. (The same thing happened to modems decades ago; at 300 baud, you heard tones; at 9600 baud and up, it sounded like white noise.)

I once pointed out to a speaker at Stanford promoting some SETI scheme that they couldn't detect any emission that the FCC would now license for a new application. He admitted that was true. For our civilization, there was less than a century of high-powered carriers. That's a narrow window to hit for SETI purposes.

Arguably, though, any sufficiently advanced civilization will monitor all RF passing through their solar system and will be able to detect anything which has a pattern which can be synched up. Although carriers are going away, all signals between distant points need some form of synchronization information. The synch information may be a tiny fraction of the transmitted data, but there has to be something upon which the receiver can lock.

Re:That's what's wrong with SETI (0)

Anonymous Coward | more than 4 years ago | (#30960592)

at 300 baud, you heard tones; at 9600 baud and up, it sounded like white noise

Those of us with a geek ear can not only hear that there is information in the 9600 baud signal, we can also identify it as a 9600 baud signal. (And to be correct, it's 9600 bps encoded using 2400 baud, not 9600 baud.)

There is a huge difference in an information-carrying signal and noise.

Encryption in space (2, Interesting)

freedumb2000 (966222) | more than 4 years ago | (#30960546)

The smart aliens will use full encryption anyways so no way to tell any transmission apart from background radiation noise anyways. Think TrueCrypt plausible deniability ;)

Don't you worry... (1)

UnFaNa (1718394) | more than 4 years ago | (#30960580)

Don't you worry! With technologies advancing and our "social skills" improving, we'll have figured out how to turn our planet into a giant cloud of rapidly expanding burning gas - or something like that - in no time. Everybody in the galaxy will be able to see us ;)

Silly humans... (0, Flamebait)

Tolvor (579446) | more than 4 years ago | (#30960650)

Silly humans... You shouldn't worry about whether other civilizations in distant star systems will detect your weak radio-spectrum emissions. That's isn't what we are scanning for in our extra-solar search.

In the beginning you humans signaled with visual signals - for example hand gestures, light houses, national flags, and road-side billboards. These are great but have very limited range.

Later you developed audio signaling for example speech, alarms, and air-raid horns. It has much further range and carries far more information, but degrades far more quickly over time.

Still later you developed electrical signaling devices, like the telegraph and early 1900's era telephone wire. You could finally transmit information over a long distance.

Later still your planet turned to the EM-band of communications. This included radio, television, radar, and a vast number of wireless devices. Your airwaves were crammed full of radio emissions leaking from your planet. Understand, these emission would barely be a carrier signal at 40 light years, and at 4000 light years would be a statistical anomaly on the EM band.

Later still you went digital and worried that people distant space civilization wouldn't hear you. Distant civilizations listen for EM band traffic. As stated, it's too hard.

If you continue to progress you will discover Distant Quantum Stimulation (the first step to efficient energy transmission). This *will* emit very strong EM-band emissions to space and is usually the sign of an emerging intelligence.

Later still will come high-energy Quantum Split-pair Sympathetic Signaling Systems (QS^4). This will come about to overcome the vast light-speed time delay in signaling between distant planetary bodies. However in using this there is sympathetic movement by unrelated quantum-bits in other solar systems. Some of those have intelligent life that will take notice.

Much much later, when you really start needing energy you will turn to Solar Photosphere Mining. This can either be "light" mining with light lenses and hot-cold energy channels (mega-batteries), or "heavy" mining like what you Earthlings call Dyson Spheres. Needless to say this significantly alters your star's appearance and can easily be seen at a distance.

In the far distant future you may discover the uses of dark matter - after all it *does* make up the vast majority of the universe. You really should know that there are ways that it can be used. It has vast potential. However any alternation and modification of the great web that is dark matter can be detected far far away. Civilization far and wide will be able to detect such an occurrence and celebrate with the graduating stellar system it's true achievement.

From here vast vistas await. There is no point in detailing them because there will be no point in searching for intelligence beyond your planet. This is because in improving your technology you also improve your capabilities. As you use those techniques more and better means of seeing further and understanding more become available.

There is no use at the lamating of an obsolete technology. To do so is to lament the passing of coastal semaphore stations and bonfire posts to warn of impending raids by Viking longboats. Your planet does not spend much energy in trying to detect such now-questionable methods of communication. Similarly other galactic civilizations do not spend much time or energy scanning for EM-band radiation.

Silly humans with their Very Large Arrays...

oblig. (1)

SeaFox (739806) | more than 4 years ago | (#30960654)

US astronomer Frank Drake has told scientists at a special SETI meeting in London that earthlings are making it less likely that we will be heard in space.

Curses! Yet another victim of the new AT&T's wireless service!

I dont think SETI will work either way (0)

Anonymous Coward | more than 4 years ago | (#30960704)

Two problems with SETI, one realistic, one hypothetical.

One, it's based one earth, Earth is noisy as hell, almost 90% of the signals that SETI picks up are terrestrial. The rest are cosmic objects, or our own satellites in orbit.

Two, space is noisy, trillions upon trillions of stars, all are producing massive amounts of energy and radio waves, most of those come in relatively faint, now consider the average radio signal created on earth, even the most powerful one. Do you think amongst all that noise, once the radio signals leave the electromagnetic bubble created by the sun, that they're even significant amongst the onslaught of random radio waves? We will find out what happens when an earth based object leaves the bubble here in a few short years as the first few probes (Voyager, Pioneer, etc) venture beyond the bow shock. If we lose contact, we'll come to the sobering reality that no one can probably hear us, and vice versa. Only the most powerful signals, which come from stars, get through. Of course I'm not an astrophysicist, so I cant say this is the fact, but just knowing that a powerful radio source will trump a lower powered radio source here on earth, I'm pretty sure the same applies to the vacuum of space, even moreso due to a lack of air and water in the vast majority of space that would inhibit most signals, creating a mishmash of radio noise, on top of celestial objects.

Load More Comments
Slashdot Account

Need an Account?

Forgot your password?

Don't worry, we never post anything without your permission.

Submission Text Formatting Tips

We support a small subset of HTML, namely these tags:

  • b
  • i
  • p
  • br
  • a
  • ol
  • ul
  • li
  • dl
  • dt
  • dd
  • em
  • strong
  • tt
  • blockquote
  • div
  • quote
  • ecode

"ecode" can be used for code snippets, for example:

<ecode>    while(1) { do_something(); } </ecode>
Create a Slashdot Account

Loading...