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Should SETI Be Looking For Lasers Instead?
colonist writes "Frank Drake, creator of SETI's famous equation, says the detection of extraterrestrial radio signals won't work, because Earth's own radio signal will only be around for 100 years. More and more of Earth's communications use cable and satellites, with no radio-frequency leakage to space. Instead, we should be looking for intentional signals in the form of high-powered lasers that could 'outshine the sun by a factor of 10,000'. Meanwhile, Paul Davies writes that we should be conducting SETI in our DNA. In turns out that an alien message designed to last millenia should be 'inside a large number of self-replicating, self-repairing microscopic machines programmed to multiply and adapt to changing conditions', otherwise known as living cells. Are we the message?"
Optical (ie: laser detection) SETI has been up and running for a while now (see Optical SETI overview for example). Drake ought to declare an interest though, since he's one of the investigators on the project.
It's a reasonable argument, but it's far harder to set up optical "listening" posts than radio ones. It cost me about 1000 uk pounds (WHY is the pound symbol banned from
The counter argument of course is that to detect laser light, the remote civilisation have to be pointing their laser at us, whereas with radio it doesn't matter since it's not a directed beam. Against that you have to offset the time-period over which transmissions of either kind could be made...
The chances of getting a radio contact may be a few orders of magnitude lower than getting an optical contact, but since the chances of me setting up an optical SETI station are precisely 0, the chances of getting 'the' signal with radio is infinitely greater than with optics, at least for me
Simon
Physicists get Hadrons!
The message only contained two words:
FIRST POST!
Are we the message?
I guess that's akin to leaving a flaming bag of poo on the doorstep.
"We apologise for the inconveniance."
Is a message allowed to read itself?
Maybe we should consider the possibility that we are part of a device to perform some calculation to find the answer to a certain big question.
Then we hardly need a whole lot of computers to see them!
yup. And the message is 41,99999999 (ad finitum)
When will I end this grieving ? When will my future begin ?
We dump pretty enormous amounts of energy at RADAR wavelengths, 24/7, across the night sky. That'll stop approximately when we have no fear of hostile aircraft showing up at our borders.
You know, never.
--Dan
And exactly since when do satellite uplink transmissions stop at the satellite? The uplink is a radio wave, albeit a directed one. It might still be possible to pick up an alien uplink signal.
seti in dna article : bugmetnot is your friend
I for one welcome our DNA-speaking, laser-shooting overlords. :-D
"When all you have is a hammer, everything starts to look like a nail"
Next thing you know, we will look for SETI in the burn pattern of a tortilla...or maybe in the reflection from a store window...
Is anyone getting my point here?
"For centuries, mankind has searched for evidence of God, in the skies, in the stars, in animals and in himself." Now do a search and replace s/God/aliens/ and ask if this is really any more a sensible statement. Not to mention, if we do find aliens, are we their peers, or are they our gods?
Final thought of the day...from what I can understand, our solar system is rather young compared to other galaxies out there. And apparently there are hundreds of planets capable of supporting life (our life, that's not even counting life that forms in some environment we consider hostile). Well if that's the case, and life/evolution is as easy as the theories make it sound (all it takes is heat and time)...then why isn't the universe like something out of Star TRek with hundreds of alien species flittering about, dropping in to violate the prime directive, establish moonbases, and so forth? Think about it.
- JoeShmoe
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-- I wonder which will go down in history as the bigger failure: the War on Drugs or the War on Filesharing
Aliens with frickin' laser beams on their heads?
Because that would rock.
Remember, it takes 42 muscles to frown and only 4 to pull the trigger of a sniper rifle.
is in our mitochondria.
I think we would probably be able to program organisms from scratch by that point, so what kind of organisms would you send to establish life on a distant planet? It would probably start off small, or virus like, but would need to be preprogrammed to evolve into something more complex. Since the evolution would be random, you really couldn't determine the outcome after billions of years.
Then it occurred to me that if we were going to go through all this trouble for a slight chance that these packets of life might just thrive and grow some brains, we would probably put some kind message in there. Then it occurred to me that we could possibly be the product of such a plan.
It is possible that the structure of the genetic code itself is an artificial creation of an advanced race. Maybe we should examine the fossil record to look for patterns in the earliest life on the planet. Maybe humans got an evolutionary speed pass to intelligence. Who knows? At any rate understanding the underlying structure of genetic programming would be necessary for understanding the rational behind choosing one structure over another. Just like programmers develop an understanding of the language they program in, perhaps we'll see some calculated order to it all.
Sorry buddy. There are a couple of dozen, possibly even hundreds of stars within 25 light years. Alpha Centuari is something like 4.1 lightyears away. So, sun excepted, it takes a hair over 4 years for light from the nearest star to reach us.
Second. What does the difficulty of getting to Saturn have to do with making sense of radio signals?
Erm, are you SURE about that?
Ignoring the real nearest star, Sol, the next nearest star is Proxima Centauri which is 4.22 light-years away... i.e. its light only takes 4.22 years to get here, not the 25 you claim.
There are 25 known stars within 13 lightyears. Their light won't take 25 years to get to us either.
Seriously. You wanna check your random information before presenting it as a fact!
People should not be afraid of their governments - Governments should be afraid of their people.
I think we're really looking in all the wrong places. We're putting human assumptions on alien life.
We assume they would be using radio communication, or that they'd bother with a high-power laser. What if their communication is completely different. Like, something we haven't even considered to be a possibility yet, even in SciFi.. In a transmission media we don't even realize, we may be receiving communications from them, but we simply don't have the equipment to hear it.. We can't even decipher what any other creature on this planet is trying to communicate, why should we even be so egotistical to thing that not only would we know how to receive their communication, but have the vaugest idea of what they're saying.
I thought the idea of SETI was that we'd pick up an omni-directional broadcast, with some alien saying "here we are, can anyone hear me" A laser would be directional. It would have to be intended for Earth, and would need to be tracking many years ahead of where we are. We aren't broadcasting the same signal, why would they? There could be many planets near by with the same idea of listening, but if no one's talking, there's no communcation.
Maybe pulsars aren't just some celestial event, maybe they're beacons, and when we're ready to go to them, we'll find more information. But for now (and the next hundred+ years), we won't be going anywhere near them. Like, we haven't even managed to get a person to the next planet yet. There isn't enough "push" to develop to the next level. Imagine if every country spent their military budget on developing space travel. we'd alerady have a flag on Pluto, along with a bunch of empty beer cans from tourists.
But no, we waste our resources blowing each other up, or making sure we're on the virge of it every day. Remember the cold war? Ya, 40 years of "I'm going to kill you all", just for it to fall apart, and both sides realize that those people we were so scared of for so long aren't really that bad.
I grew up knowing the Soviet Union was the evil Red Army, who had so many weapons pointed at us because they hate us so much. Now, thanks to the fall of the Soviet Union, and the rise of the Internet, I now frequently talk to a Russian, and really, he's a nice guy. I've seen some beautiful pictures around where he lives, where not too long ago I would have believed was a frozen wasteland.
If only all of our governments would give up on this nonsense and cooperate in things, or better yet, ditch the whole "This is ours, you can't play with it" mentality, we'd make a lot more progress.
[rant mode off]
Serious? Seriousness is well above my pay grade.
The divergence of a laser beam is, assuming ideal optical components, mostly dependent on the diameter of the beam where it starts. You can take a big telescope and let the light pass through in the opposite direction, so let's say, a diameter of 4 meters. For visible light, that will generate a beam with a divergence of 1e-14 sr. So, to get to 2e29 W/sr, you need a laser with a power of no less than 2e15 watts. (Compare this to a mid-size electrical power plant at 1e9 watt...)
Yes, there exist lasers that can generate ultrashort pulses in the near-infrared, with such a high peak energy, say 100 femtoseconds (100 fs=1e-13 s) and 100 joules per pulse, so there you have our desired fluence.
Unfortunately, such lasers can only fire something like one shot per second. If you really want to appreciate the high peak power, you need a camera with a shutter time of 100 fs. Imagine looking at the sky with such an ultrafast camera. The chance that you actually manage to catch a flash from this laser is virtually zero, unless you have a way to know when the flash is going to come. Someone who is looking at a nearby star and expecting flashes is more likely to have an aperture time of 0,1 seconds or so in order to capture any photons at all. At 0,1 seconds aperture time, the laser is no longer 10,000 times more bright than the nearby star (that is, our sun), but rather 1e8 times weaker.
So, it is unlikely that this is going to word, assuming that someone is looking at us anyway.
Avantslash: low-bandwidth mobile slashdot.
The question "Are we alone?" is one of the most important philosophical questions; keep in mind that what we call "science" today was once called "pysical science". Philosophy was the profession of scientists centuries ago, and should be part of the toolkit of scientists today.
From a observational standpoint, you have the (yet unproven) theory: There is life outside Earth. In order to try to prove this theory (disproving it is much harder =), you gather data and analyze it. That's generally considered part of science. If for example, Mars missions finds self-replicating life, that can provide an answer to the simpler proposition. The harder one -- intelligent life -- would still need to be shown in some other manner. (Unless we found self-replicating intelligent life on Mars, of course.)
As for the "who cares, I'll be dead by then!" narrow-focused people, keep in mind that the tools and networks being developed for SETI -- massively parallel data set computations -- have usages for other areas of "science" that you would probably consider to be science -- protein folding, for example.
With the promise of quantum communication, it is conceivable that (if Quantum communication is indeed feasible) we should be focussing our optical light search on specific photons of light.
Anyone know about beam splitting entangled pairs etc. Many moons ago, Einstein, Podolski, and Rosen carried out there unusual experiment whereby the they observed what is now known as quantun weirdness. A photon in an entangled state could be split using a sophisticated 50:50 beam splitter. Each split photon could travel off in opposite directions and appear to be twins, in the sense that any change in behaviour of one would instantly (exactly synchronized regardless of distance!!!) be felt by the other, its twin.
Evidence that this was no fluke is gathering thanks to continuing experiments, yet it is still not in stone.
My reasoning is that if this phenomenan is genuine, it could be one way extraterrestrials would chose to contact us. Why not. They send a conventional optical signal, only this time encased in a surrounding cylindar of light, thus allowing for the entangled photons charateristic properties to be influenced only by this cylinder of light. Allot can till go wrong so conceivably, the 'ET's' would send a large stream of such light cylinders- the centre of which is a stream of entangled photons. That way any measurement of the entangled photon would cause an immediate change to its twin (The twin photon - of entangled pair)would presumably be archived on the alien world bouncing back and forth in a cavity (not unlike the cavities we use today - only presumably far more advanced.) So, once change is observed, an immeditae alarm bell is triggered. The ET's can know instantly someone/something has comeinto contact with their signal. Just like Earth SETI, the ET SETI would categorise all their findings and have mant false positives. They would probably already have chartered the area of space to which they send a signal. They may know the only objects (meteorites, stars, planets, commets...) that are likely influences over the transmitted light signal. Hence, if we Earthlings intercept the light in a very manufactured manner (i.e fire a encoded light signal of our own into theres, they are likely to get some unusual data back at there end - instantly.
Anyway, lets face you can't have an interest in SETI without being imaginative.
All Im tring to say is.
1) If I were a highly advanced ET, I would use Quantum entaglement (if it is indeed feasible) to transmit photons of light.
2)I believe we should start sending entangled photons of light, encased in our own manufactured cylinders of background light, out into space.
3)I hope SETI read this.
Let's see, you are comparing our solar system to other galaxies? You must realize that the scale of a solar system in relation to the scale of a galaxy is unbelieveably small, right? Ie., there are a (suitably big number) of solar systems in our galaxy alone.
Think of it this way, when you look at a picture of a galaxy, and you see the fuzzy white haze, that haze is (to quote Dr. Sagan) billions and billions of stars.
Now step back, and look at a Hubble Deep Field photo. What do you see? A (suitably large number) of galaxies each of which contains a (suitably large number) of stars/solar systems.
If you really consider the scale of the universe and the scale of time that the universe has been around, it seems pretty obvious that there is a lot of life out there.
The reason we don't have the Star Trek thing going on is that wonderful little thing called "c". That, and I guess they are all trying to learn English...
A house divided against itself cannot stand.
as /. users rush to see who can excel the other at sophistry. The rules are simple.
Now, let the games begin!The idea here seems to be that at some point we'll just decide to abandon the whole RF spectrum because we have better mechanisms of comminucating. This is implausible to the point of silliness. We *will* have better mechanisms, but the RF specrum is still there, and still as usable as it ever was, and if no one is using it, why, it will be very cheap. So people *will* use it, of course.
Imagine, for instance, that UHF TV goes away, and non one wants the spectrum any more. Now you can build a local TV system for the cost of a transmitter (which you can get as cheap surplus). So lots of people will do that, so there will be lots of use of the UHF spectrum. It will just be by people doing more interesting thigns than it was before.
You bullheaded humans think you have it all down pat, don't you?
The sad truth is that my planet found your planet from the leaked signal of an '802.11b' device owned by Dave Stewart in Provo, Utah as he was attempting to download a copy of Blue Oyster Cult's Don't Fear The Reaper song. But soon no other intelligence will be able to find your planet due to the decline in the P2P that was a beacon in the long dark night of space. You see, it's the legal dickering of the RIAA that is more a threat to your society than high powered lasers... so sad.
Dedicated Cthulhu Cultist since 4523 BC.
More and more of Earth's communications use cable and satellites, with no radio-frequency leakage to space.
Why would there be no radio-frequency leakage to space using satellites? Some of the signal sent down to earth probably bounces back to space. More importantly, most of the radiation beamed up to satellites goes right into space! There's no way those beams are so narrow that they only hit the satellite's receiving antenna...
...a post consisting only of a single non-alphabetic character, getting modded to +5.
Truly we live in amazing times.
-CausticPuppy "Of all the people I know, you're certainly one of them." -Somebody I don't know
No no no! Aliens communicate through a series of large stone monoliths! Don't you guys pay attention?
"We shall party like the Greeks of old! You know the ones I mean." - HedonismBot
Now from the car's perspective, the light is moving away from it at C, but it's moving forward at .5C, so the light is only getting closer to the observer at .5C. Hence it takes two minutes to reach the observer. At T+1 minute, the light has not reached the observer. So the guy in the car is surprised by the announcement that it has, and sends back an instant communique for confirmation.
"Confirmation?" asks the observer, "I haven't sent you anything yet!" After all the light has not yet reached the observer, so how could he have sent the communication?
You're assuming there's such a thing as absolute time, which Special Relatively disproved.
So there is no such thing as T time. There is O(T) - Observer time. And R(T) - caR time. Let T0 be the time when the car flashes its headlights, and T1 be the time when the light from this flash reaches the observer.
So the car flashes it's headlights at R(T0). The observer sees the flash at O(T1). The observer then immediately sends an instantaneous message to the car, which is recieved at R(T1).
To both parties, at the time T1, the light ray from the headlights has reached the observer. The difference is that (R(T1) - R(T0)) > (O(T1) - O(T0)).
Your thought experiment assumes that there is a "universal time". So that one minute for the car is the same as one minute for the observer. This is incorrect.
... light-speed communication at least, is a lot of patience!
Unless the first ETs we encounter live in a different time dimension. What we consider couple of thousand years, might be a few minutes for them, who knows?
The purpose of life is to find the purpose of life.