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Extraterrestrials Probably Haven't Found Us - Yet
kasparn writes "The Guardian today has a story about the Danish astrophysicist Rasmus Bjoerk, who recently conducted simulations on how long it will take to colonize the Milky Way. The basic idea is to send out probes in different directions (including various heights above the galactic plane). He estimates that it will take some 10 billion years to explore 4 % of the Milky Way. Since the age of the Universe is of the same order, his conclusion is that aliens can't have had time required to find us yet."
We will be in a lot of trouble if the Cylons find us first.
Why 1/10th c? Why not 99% of c? Why not faster than c? Granted faster than light travel is nothing more than theory and dreams at this point, but this article makes the assumption that other civilizations have not progressed in the field of physics any faster nor further than we ourselves have, to date.
I am, therefore you think.
Sheesh, talk about "proof by lack of imagination." This is supposed to answer the Fermi Paradox?
You can't explore a galaxy with a handful of probes. 72 probes??? First of all, if you're going to do it that way, you'd create hundreds of thousands of probes, if not millions of probes (mass production would reduce the cost). Second, you still probably wouldn't do it that way. You'd wait until you had the technology to make self-replicating probes, and the galaxy could potentially be explored in thousands of years.
Not impressed by this guy's argument.
Sometimes it's best to just let stupid people be stupid.
Come on. 4% is a hell of a lot better than your odds of winning the lottery and that happens *everyday*.
Plus he's not taking into account multiple alien races. So that's like double 4% which is almost 8%. Do that a few hundred times and you get 108%. This guy clearly doesn't understand math.
This figure of taking billions of years to explore the galaxy is utterly wrong. Actually, it only takes a few dozen million years to colonize the entire damn galaxy, which is a lot more effort than merely exploring it.
This figure is based on some very reasonable assumptions. Colony ships travel at much below the speed of light. Each colony gets a thousand years of development time from first colonization before it starts sending out its own colony ships. As you can see, even though it seems quite "slow", thanks to the magic of exponential growth, the entire galaxy is colonized in short order.
We won't merely be discovered if aliens exist - we'll be colonized. That's the most likely scenario for running into aliens. If they never spread beyond their home planet, they'll just be one star out of trillions - but if they do start colonizing, we'd find them everywhere.
Cyde Weys Musings - Scrutinizing the inscrutable
To paraphrase: But Sir! If we only send 8 probes it'll take billions of years to search a mere 4% of the Milky Way galaxy!
That's why you have to make the probes self replicating.. utilizing in-situ resources to make more probes at each star they visit, the growth becomes exponential and it only takes a few thousand years to search the entire galaxy. And seeing as we're visiting all these stars anyway, how about looking for planets that don't have life on them, but have nice suitable conditions for starting life on them. Cover a virgin planet with a wide variety of Earth lifeforms and fly on.
How we know is more important than what we know.
Traveling at the speed of light, it would take a quarter million years to reach Andromeda. What's more is that if I went into statis now, the compound interest on my savings would pay for the journey.
Whatever his assumptions are that leads him to 4%... it seems that he is considering only the probability that any ONE alien civilization is looking. But in all likelihood there are many, if not millions of alien civilizations out there than may be search, so the probability that any ONE of those million will find us seems quite a bit higher than 4%.
"If an alien race has had advanced technology for 100,000,000 Trillion years, then they'd have plenty of time (and would probably have technology more advanced then sending out physical "probes")."
when they show up, please ask them how they survived the big bang.
They want all of our "base"?
Also, this simulation was about colonization. It's a lot easier to find something than to colonize it, especially in places that aren't very conducive to supporting life.
Bitten by the ole RTFA bug eh. The quote from the article is
He found that even if the alien ships could hurtle through space at a tenth of the speed of light, or 30,000km a second, - Nasa's current Cassini mission to Saturn is plodding along at 32km a second - it would take 10bn years, roughly half the age of the universe, to explore just 4% of the galaxy. His study is reported in New Scientist today.
No mention of colonization there.
Plus
Mr Bjork confined the probes to search only solar systems in what is called the "galactic habitable zone" of the Milky Way, where solar systems are close enough to the centre to have the right elements necessary to form rocky, life-sustaining planets, but are far enough out to avoid being struck by asteroids, seared by stars or frazzled by bursts of radiation.
So there's that too. Looks like you should have taken a look at the article first.
You'll have that sometimes...
I agree. He's only basing his assumptions on our current capabilities and applying them to an unknown alien civilization. Great that he's making these assumptions but his final conclusion, We have not yet been contacted by any extraterrestrial civilizations simple because they have not yet had the time to find us. Searching the Galaxy for life is a painstakingly slow process., is just jumping to conclusions, perhaps invalid for the work he did.
No one knows what aliens are going to look for in a planet. Our planet could be written off as an inhabitable nitrous sphere. They might be non-carbon based life forms. They could have progressed technologically much faster than we did as you suggested. By assuming aliens match our capabilities, he made an unstated assumption that was key to actually understanding the conclusion.
A more fitting conclusion from his work would be that it would take US 10 billion years to search a small portion of the Milky Way for life at our current technology levels.
We will be in a lot of trouble if the Cylons find us first.
Actually the "cylons" will find us first, it is far cheaper to send robotic explorers out. Then if anything interesting is found send the "manned" missions.
Worse than that- the researcher assumes:
1. That they can't develop PROBES that travel faster than 1/10th the speed of light.
2. That probes of this form that would keep running long enough would be so massively expensive that even the most ambitious race would only be able to build 8 of them (He does address this complaint, and also considers 200 probes instead of 8, and von Neuman machines instead of static probes, neither of which drop the figures below 4x10^6 years to explore a mere 4% of the Galaxy).
3. He doesn't even consider non-material, photon-based probing methods, which would increase the rate of exploration by a factor of 10.
SJW: a person who perceives an injustice, and while correcting it, commits a greater injustice.
Come on, they haven't visited us yet? There were yet another case of alien abduction as reported by the World's Weekly last week.
One of these Turing machines reached Earth about 4 billion years ago. It first had to start by building very simple amino acids, then it graduated to proteins, then to RNA and then to DNA, and then these DNA machines built bodies around them and started using natural selection to evolve into more and more capable organisms. The final aim of these DNA structures is to build powerful radio beacons and send the information back to the original aliens who created these molecules and scattered them to the (solar) wind.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
We are currently broadcasting the galactic equivalent of "Eat at Earth" sign. Remember we consume "lesser" lifeforms for food. I do love a good steak! Who knows if the aliens who find Earth will consider us as equals or as appetizers.
I am sure their galactic physicians will recommend they don't eat too many humans from the Northwestern Continent due to cholesterol or something, but that they can eat all the yellow humans from the east they want, even if they will be hungry again in a few parsecs.
I only look human.
My mother is a halfling and my dad is an ogre, so that makes me an Ogreling
I'd hold off on criticizing others for a lack of imagination. Don't you realize that self replicating probes will doom us? We will be galactic spammers, the aliens will wipe us out as a nuisance. Or our probes will harvest the planet they pray towards, the aliens will wipe us out as heretics and blasphemers. At a very minimum the probes will be crossing the border without proper documentation, the fines and impound fees could leave us in "debtors prison" for millennia.
"photon-based probing methods"
You mean looking at stuff through a telescope?
More puzzlingly, he assumes these probes can repair themselves for and keep running for billions of years, but they can't self-replicate. Really? If the probe can repair every potential internal probem on its own, the capacity to self-replicate should come almost for free.
Ben Hocking
Need a professional organizer?
The study in question does not even address the Fermi Paradox in any meaningful sense, much less "resolve" it. In fact, if this study is being offered as a resolution of the Fermi Paradox then it suggests the researcher does not understand why the Fermi Paradox is a paradox at all.
The fundamental difficulty with any explanation offered for the complete absence (so far) of any sign of other intelligent life in the universe is that the proposed explanation has to be universally valid.
The span of time for colonization, or dispersal of replicating probes, or of building vast telescopically detectable artifacts is so great that even one single exception from any proposed explanation would be capable of generating ubiquitous evidence in a tiny fraction of the life of the Universe.
Simply describing some model for exploration, and then arguing that this model won't do the job says nothing about other models. This study apparently does not consider the geometric growth that occurs with any exploration program that uses some form of replication of explorers, for example. If replication is thought to be impossible then the study would have the high hurdle of convincingly demonstrating this. (The material evidence of life on Earth seems to argue persuasively against it though.)
Arguments that "interstellar travel is impossible" would qualify for explaining why alien artifacts aren't being found locally (but do not address communication signals or telescopically detectable artifacts), but require convincing arguments that this is indeed true. On the contrary, physics does not seem to make this impossible at all, just very costly and slow. Too costly and slow for anyone to bother? Not even one single civilization?
The Fermi Paradox seems to be telling something important about the Universe. If only we knew what it is...
Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
That's why I laugh when people spot human-sized UFO craft. If there are UFOs here, they're microscopic.
Assumptions are just that, assumptions. You can laugh all you want, but to me, it just shows one more scientific dogma. The attitude of "knowing it all" is sadly very prevalent here on Slashdot, and probably why so many spend time writing here, instead of discovering new stuff.
The problem is lack of creativity. In 0.5 seconds, I thought of nano-UFOs. Send one, or trillions of those, and let them dig into a moon or planet to rebuilt itself into a fully fledged macro-sized "UFO". Or, maybe if you want to "recreate yourself in your own image", why not send out organic "bombs"? Etc. etc. There are so many possibilities when you dont restrict your mind.
Just because you cant think of it, doesnt mean it isnt possible or thinkable. Please free your mind! There is so much more to know than we already know! And instead of giving focus to more effective ways to kill people, why not science of life?
http://www.debunkingskeptics.com/
I reckon theres a Slashdot survey on the best way to explore:
How would you prefer to travel?
a. A blue Police Box that can traverse space and time, with a hot British former 'teen star' that is obviously in love with your weirdness.
b. A big ancient ring that can take you anywhere where there is a corresponding ancient ring, but you keep bumping into Egyption dog people who try to kill you.
c. A large dinner shaped spaceship that does warp factors, but you get to shoot at klingons and make sexy time with green chicks (remember its all about the Journey!) Just dont get assimilated by Bjork!
d. Travelling with the Robinson family and a stupid robot that shouts "Danger" long after it stopped being funny. Oh and a pedophile.
e. In a ship that can make the Kessel Run in less than twelve parsecs - With a great big hairy Wooky and a gay robot.
e. Spending time on the only ship to have survived an attack by robots with KITT in their face, where it is a daily battle to stay alive.
f. On a moon that was flung out of orbit by a massive thermonuclear explosion initiated by the build up of magnetic radiation, which there is much debate as to it being caused by global warming.
g. Traveling across universes with a guy that looks like Mike Moore, where each new universe you 'slide' into is exactly like being on LSD.
h. On a ship with a dorky hologram an evolved cat, a computer with an IQ of 6000 and a very stupid robot, but every day is hilarious!
I. The space shuttle. (yawn)
this just in, 1000 telephone sanitizers landed at Kennedy Space Port.
If an alien race has had advanced technology for 100,000,000 Trillion years...
Holy shit, Tom Cruise posts on Slashdot!
God invented whiskey so the Irish would not rule the world.
...Aliens have not visited earth or manipulated genes in some way.Average weight of humans up... sounds like and interstellar Hansel and Gretal
Help test the
1. It's incredibly stable. It's launching an exploration program using probes that are going to take billions of years to get a result back to the original civilization. It expects to be around to pick them up.
By the same logic:
2. Individual members are incredibly long-lived, or the society is static and conservative enough that individual goals are submerged. They expect that the people around in a few billion years still care about the stuff they're doing, AND they care about the people who'll be around then.
The technology he's postulating is also very advanced.
3. Large scale space-based industry is routine enough for them to build probes capable of refuelling themselves using the raw materials in an as-yet-unexplored solar system, with surplus fuel to launch and recover the sub-probes. If they can do that, they can do the same thing in their own solar system.
If the probes are cheap by their standards, there's no reason not to keep building them indefinitely. So let's say they're expensive. Let's say it takes this civilization a hundred years to build a probe. Why do they stop after 800 years? They're long-lived, stable, conservative, so assuming they have the will to do it in the first place why would they stop building probes? As the author notes, probes break down.
So what happens when you add another probe into the search every century, indefinitely? Well, after a million years you've got 10,000 probes out there. Now you're looking at a search time measured in millions rather than billions of years, and it only takes millions of years to do it.
But why are they doing this? Looking for planets to colonize, perhaps? If they're just looking for civilizations they'd do much better depending on "signal intelligence".
But if they've got the ability to send out colonies, even the most conservative long-lived space-based civilization is going to figure out eventually that they don't actually need habitable planets to support a permanent colony. It's riskier without habitable planets, but even if the planetless colony is 10 times less stable than the home system you're still better off with your civilization in two baskets. And before long (in the terms of this civilization) you've got a roughly spherical shell of colonized star systems, expanding as fast as they can reach new systems. At 0.1C colonizing (not just exploring) the galaxy is going to take mere millions of years.
On the other hand, what if the self-replicating probes are members of the designing species themselves?
So either this level of technology is impossible to achieve, or we're back to the question of why no species has done it yet. There's lots of plausible answers, of course, but this paper sheds no light on them.
As science advances, we learn more and more about the forces that drive nature, and the laws they abide by. Those examples you gave us don't violate any of the known physical lays. I find it a bit disturbing that the advancement of science is taken to mean that everything will become possible. Instead, we better know the posibilities and certainly the impossibilities. Maybe we will find a way around these laws, but I highly doubt it.
I for one would really like to explore the universe and make contact with alien species. Unfortunately, my just wishing this is the case doesn't make it so.