Now that we know how to detect exoplanets by their effect on the star's wavelength, what are the implications to the Drake equation? [1]
Originally, we estimated that habitable planets were very rare. Then we discovered exoplanets, and soon after, habitable exoplanets.
Drake also started by looking for radio signs of intelligent life. Now we humans use frequency-hopping burst digital transmissions and the power level is much lower, so detecting another planet by its radio signature seems a lot less likely.
Since earth has been habitable for at least 3 billion years [2], what is the probability that intelligent life (in our galaxy) is aware of this planet and wants to look at it? My back-of-napkin estimate is that we are out on a limb of the galaxy and therefore very visible.
> "what are the implications to the Drake equation?"
I'm not a fan of the Drake Equation. The "equation results" section of the wikipedia page shows the range of variability: there may be anywhere from hundreds of millions of civilizations in our galaxy, to maybe we're the only one in the entire universe (a difference of close to 30 orders of magnitude), based on different guesses for some of the other parameters. Both sets of numbers are using the current understanding that we can discover exoplanets etc. and that they're not terribly rare. Prior to that understanding, estimates varied by another 5-10 orders of magnitude.
In other words, these newer discoveries don't get us particularly close to a definitive answer from the Drake Equation. We still don't know whether there's intelligent life at millions of stars in each of billions of galaxies, or if it's possibly just us.
The only sort of data that would let us actually use it to generate a meaningful answer would be the discovery of more intelligent life.
The Drake equation was meant to be illustrative; lowballing everything (particularly the L term, since we were in the midst of the maddest of MAD at the time) and still coming up with a non-zero value was really the point. As long as what you're plugging in isn't on the order of "the Scriptures say it can't be, therefore it's zero", you will arrive at a non-zero value, and that makes at least the attempt to find and make contact with other technological civilizations reasonable.
> "coming up with a non-zero value was really the point."
When you're multiplying a bunch of non-zero quantities, that's the only possibility. It's not really illustrative or useful, though -- particularly because the range of possible estimates still includes "we are alone in the universe".
You don't need the Drake Equation to tell you that it's reasonable to explore and search.
I think what he is saying is that the Drake Equation does not get us anywhere useful. A theory that has such a wide range of outcomes does not eliminate much - and most science is eliminting options not demonstrating a truth.
In fact the less-than-helpful results are a useful reminder of Karl Poppers maxims
Maybe I missed it but may I suggest one extra filter to be applied - once a civilisation reaches a level of technological sophistication, it finds the base code for the matrix, works out how to dial out and leaves, going up to the pan-galactic teenagers bedroom we are running in.
Thus the answer to Drake and the filter question is no one is around because there is an exit to a more interesting universe.
1) "I truly wish I could answer that question." - Having recently re-kindled an interest in space left dormant since childhood, I'm thinking this is the kind of thing I could happily dedicate my life to.
2) "I wonder if a hybrid of Google Answers and Kickstarter to answer this kind of interesting question could thrive?" - Apparently, there have been a few attempts at the latter part at least[1][2], but the list of projects is pretty short. Crowd-funded research with open-access findings seems like potentially wonderful thing.
What kind of periodic wobble would our Sol produce from our very-many body solar system? Would it be easy to decipher, or easier to catalog as background noise?
Maybe we'll start seeing advances in telescopic technologies and analyses in the years to come -- to pick up on more complex periodic motion of the more complex solar systems.
Just got me thinking, there might be some interesting results from making these kind of observations from say Voyager distance and scaling the resolution of the measurements accordingly to match our results of far more distant system.
Not knowledgable enough in the area to know if this would be worth doing.
If a clone of our Solar System were out in space our chances of detecting it would be extremely low.
In order to detect Venus or Earth it would require around a 1 in 100 chance alignment of the orbital plane relative to the observer to be detectable via the transit method. Jupiter would be detectable through radial velocity techniques but it would take a minimum of 12 years to confirm a single orbit and more likely it would take at least 2 orbits for a proper confirmation. And even so it would be a coin flip on whether the orbital plane was aligned properly to be detectable at all.
With the increased sensitivity of the new instrumentation used to detect the Alpha Centauri B planet things are improved slightly but still the chances of detecting an Earth-clone via radial velocity aren't that great.
Where are you getting your chances from? Is there some theoretical limit on the sensitivity of the radial velocity technique, independent of current technology?
(edit): This spectrometer is supposed to be capable of detecting an earth-clone, starting around 2016:
This graph shows its predicted sensitivity (green line for a sun-like star), compared to exoplanets previously detected by the same method (gray circles), and solar system planets for reference:
You can get a rough estimate of the chances of being able to observe a planet via the transit method by dividing a star's diameter by half of the orbital diameter of the planet (for Earth it's something like a 1:300 chance).
For radial velocity the signal detected is proportional to the sine of the orbital inclination. The detectability of Jupiter depends highly on which instruments are being used for observation. My "coin flip" estimate was just a SWAG. If you make use of the best radial velocity detection systems today which have a sensitivity of around 1 m/s and compare that against the maximum 13 m/s radial velocity that Jupiter imparts on the Sun then you end up with much higher chances of detection (80+%) assuming a random relative orbital inclination, but that assumes there aren't any other sources of noise involved.
This is the Fermi Paradox ( http://en.wikipedia.org/wiki/Fermi_paradox ). The more we learn about space, the more clear it becomes that extraterrestial life is more likely. But where the hell are they?!
From a technical point of view I know that there are two teams searching for exoplanets around Alpha Centauri [1]. Hopefully this means that the other team will be able to provide evidence that correlates this find.
From a human point of view, I'm in the southern hemisphere and we will have clear skies. Alpha Centauri is still high above the horizon at this time of year. Tonight, I'm going to take my two kids outside and point out Alpha Centauri to them. I'll be able to tell them about it. Tell them, that now we know, part of what’s there. Tell them, that there is likely other worlds. Worlds more like ours orbiting that tiny, almost insignificant spark of light.
I actually find it very scary that the nearest planet not in the solar system is 4.3 Light years away!
If FTL / Close to light speeds are impossible in this universe, we're just left with generation ships [1]. It seems that there is a very good chance that we'd be stuck on this rock called the earth forever. Really need to take better care of it.
Do we need a planet at all? Seems like an easier option for being non-Earth dependant would be to develop vessels that are self sustaining and which perhaps mine asteroids and gas clouds to get what they need. The whole getting onto and off a planet just adds more complications than its worth.
Alpha Centauri feels far away because our lifetimes are so ridiculously short, and we're so unfathomably economically poor, compared to the age of and resources available in the universe. These limitations don't have to apply to whatever our descendants will be a few centuries or millenia from now.
To them, a trip to Alpha Centauri might be a weekend lark.
The nearest planet "that we can detect".. What says that planets can only form around stars? Yes, its most likely since those are some of the biggest gravity sources, but if you have a failed star system, or accumulation of mater out in deep space, no reason it can't aggregate and form its own starless planet
1/10 of the speed of light is still pretty fast. Helios[1], the probe that holds the speed record from all our spacecrafts travaled at 252 792km/h. That's still less than one 1/400 of the 1/10 of the speed of light.
I understand basic physics and statistics but when I think of the fact that they teased out a 0.5 m/s signal on something 40 trillion kilometers away, it might as well be magic.
I remember reading a long article (which I can't find right now) about those searching for planets around this system for many years. Great to hear that progress has been made.
The article doesn't actually say which of the three stars of the Alpha Centauri system this planet is orbiting, though it implies that it's orbiting Alpha Centauri B.
Originally, we estimated that habitable planets were very rare. Then we discovered exoplanets, and soon after, habitable exoplanets.
Drake also started by looking for radio signs of intelligent life. Now we humans use frequency-hopping burst digital transmissions and the power level is much lower, so detecting another planet by its radio signature seems a lot less likely.
Since earth has been habitable for at least 3 billion years [2], what is the probability that intelligent life (in our galaxy) is aware of this planet and wants to look at it? My back-of-napkin estimate is that we are out on a limb of the galaxy and therefore very visible.
[1] http://en.wikipedia.org/wiki/Drake_equation
[2] http://en.wikipedia.org/wiki/History_of_Earth