Slashdot Mirror
Billions of Planets In Milky Way?
jeffsenter writes, "The Washington Post has the story: 'NASA scientists using the Hubble Space Telescope have discovered what they believe are 16 new planets deep in the Milky Way, leading them to conclude there are probably billions of planets spread throughout the galaxy.' What sets these potential planets apart is they are in the central bulge of the Milky Way where most stars are located. More planets in the galaxy means more chances for life." The 16 are planet candidates at this point, until verified by spectroscopic measurement of their parent stars' wobbles, which probably can't be done until the James Webb Space Telescope files in 2013.
This is a great example of a ground-based telescope that could easily rival any space telescope:
OWL Telescope
As for us seeing other intelligent life, just watch for planets to spontaniously blow themselves up.
Sadly, that may not be a bad idea. So assuming that we do not ourselves generate this kind of signature, we may be able to see something in a decade or two. Looking for extraterrestrial nuclear detonations would probably make a fine grad school project!
To the making of books there is no end, so let's get started
I think that's because space manufacturing hasn't been made a reality yet. I think once mirrors or even optical lenses are made in zero-gravity in a place where size isn't nearly so important, space-borne telescopes could well out-perform the earth-based.
It's because you can't draw conclusions from a sample size of 1. Suppose that you've spent your whole life in a blue room. You know there are other rooms out there- but can you assume that they are all blue? Can you assume that most of them are blue? Even if there are other blue rooms, would they be the same shade (Cerulean, let's say) as yours?
Even assuming that we are not unique, there is a big difference between thousands of stars with planets and billions of stars with planets.
You are reading a copy of my copyrighted post.
Ah, but the most kick ass telescope would be one located on the far side of the moon. No earth light to interefere and, to quote a book "This place has no atmosphere". With the 1/6th gravity, the mirrors could be much larger as well.
Fly me to the moon Let me sing among those stars Let me see what spring is like On jupiter and mars
Yeah I used the life angle to get it posted, but there is a little bit of substance to this increased chance of life thinking. Even though the central bulge is not the best place to find life, finding plenty of planets in the central bulge, where large scale planet formation was somewhat in question, suggests that planets are formed around stars everywhere, not just in our galactic neighborhood. If planets are formed everywhere as opposed to just in select parts of the galaxy there are more planets generally and planets present in parts of the galaxy that are more hospitable to the formation of life.
It is not just the area of the galaxy around earth that has planets. Planets are probably helpful for the formation of life. More planets more chances for life.
I'm curious how this will help nail down some of the parameters for the famous Drake Equation N = R* * Fp * Ne * Fl * Fi * Fc * L.This new guestimate will help narrow down f sub p, the fraction of stars that have planets, and go some distance to narrowing down n sub e, the number of planets that can support life per star. As our resolution power increases the better able we will be able to come up with better guestimates.
The answer might be zero anyway. After proposing the equation Fermi pointed out if intelligent life is so common, where are they? A space faring civilization travelling at 1% the speed of light would cross the galaxy in ten million years. Relative to the age of the Milky Way Galaxy, ten million years is a very short period of time. This is called the Fermi Paradox. Where are they?
I think we just don't know enough yet and we haven't been looking for very long. I think our technology will help us give a more accurate answer to the Drake equation within the next 100 years. We may even find evidence of life on other worlds when we can detect free oxygen on worlds in habitable zones light years away. And that could happen within the next decade or two.
For those people who say the aliens are already here, I would ask would an intelligent space faring civilization travel hundreds of light years just to kidnap some redneck farmer and give him an anal probe and then make crop circles in his fields? I suppose if it was some alien fratboy hazing ritual they would.
"You'll get nothing, and you'll like it!"
The article said these findings were based on 7 days of observations, using the transit method. In this method, the planet passes in front of the star, causing a very small, but sudden and periodic drop in the brightness of the star. Presumably, they don't claim to have a candidate unless they see multiple dimming events. If so, the longest possible orbit they could have observed is 7 days, meaning the planets are extremely close to their stars. Even their moons would be inhospitable.
However, as another poster pointed out, these systems may also harbor smaller planets in more favorable orbits. In fact, some researchers believe that smaller rocky worlds can only form with the assistance of disturbances created by the gas giants.
In contrast, other researchers are skeptical that planets can form at all in the inner regions of the galaxy because of the high star density. Even if they did, they might not be able to harbor life because of all the radiation from said stars.
As another poster pointed out, however, we don't necessarily know the limits of conditions that life may form. This is getting a rather fanciful, but perhaps high-temperature silicon-based rock monsters are real, like Season 4, episode 7 where Kirk fought the lava man with the Abe Lincoln avatar (just kidding, I made that up...or did I?).
Assuming we don't kill ourselves before our sun fails catastrophically:
What remains to be determined are:
So from this, a good guess might be 1/1700 of the rocky planets out there are habitable. If our solar system is typical, we have 5 rocky planets, so there would be a (1 - (1699/1700)*(1699/1700)*(1699/1700)*(1699/1700)*(1 699/1700)) or chance of our solar system evolving any life at all, or about 0.29%. Multiply times the odds of a habitable planet having intelligent life at any given time (about 1/2), and we have about a 0.145% chance (only a little better than 1/1000) of finding intelligent life in a solar system with rocky planets.
Nowhere near the 1 in a million long shot speculated, but this assumes that Earth is typical, which is not necessarily a valid assumption.
Check out my sci-fi/humor trilogy at PatriotsBooks.
There's a theory that no lifeform will evolve to become significantly more intelligent or technologically advanced than humans, because at the level of intelligence we've reached an increase doesn't offer us an evolutionary advantage. We're already able to survive and breed, and indeed dominate the planet. And as a society gets more advanced in terms of technology, its members require less and less intelligence to survive and breed. This will eventually lead to a slow decay in intelligence which slows or stops the technological advance as well. The species will ultimately end up in some kind of a permanent, static equilibrium state if it survives long enough. We may be just a couple of centuries away from this ourselves.
IIRC, Gliese catalog lists only those stars found within 70 light-year radius from the Sun.
In that very tiny sample, year, you are probably right.
But if you look at the whole Galaxy, you are not correct. The Sun is surely a tiny dwarf star.
Spinning liquids to form mirrors works on Earth because Earth's gravity acts perpendicular to the plane of spin. We would need some way of replicating those two forces in space. All the methods I know about would cost more than simply launching a solid mirror.
A method of putting cheap mirrors into space that I proposed to my physics mentor a few decades ago is to use inflatable mirrors. He brushed off the idea at the time. Now, though, NASA has research on the general concept:
NASA Tech: Parabolic Membrane-Thickness Variation for Inflatable Mirror
A Google search for inflatable mirrors turns up many more results.
Taking stuff apart since 1969 (TM)
It appears to me that all of your quite precise estimates are made on the basis of a single data point: our solar system.
So the confidence factor of these estimates is pretty low, with a sample size of one out of a population of planets (or stars with planets) in this galaxy that is a pretty large number (perhaps billions, but that's a guess).
Also, given that we know exactly zero about the processes that operated to produce (or will hopefully produce within another Darwinian cycle or two) intelligent life on this planet, it is a remarkable leap to assume that half of the habitable planets harbor intelligent life.
Just for the sake of irrational, Slashdot-style argument, let's suppose that the following mechanisms are responsible for human evolution to the top of the food chain here on the third rock from the Sun:
1) A world that is mostly water
2) A large moon that causes significant tides
3) A paleoclimate pattern of greenhouse and ice ages, without slipping over into either runaway greenhouse effect or having the ice ages crank up the albedo so as to remain permanent (a neat trick, for which we have no explanation)
4) A molten core that lasts just the right amount of time, which presumes either (or both) the tidal effects of a large moon or a specific percentage of radioactive elements sufficient to keep the home fires burning
I could go on, but you get the idea. We know zilch about what causes intelligent life to arise, whether it is the normal course or an isolated instance, and exactly what teatures of our world have contributed to this. Certainly a regular series of mass extinctions would seem to be a prerequisite for life to advance to more versatile forms. And of course, there need to be stable intervals in between the periods of catastrophe for newbie life forms to develop before the dice get rolled again (and again and again). We certainly had a number of mass extinctions before humans (or the critters that eventually became humans) arrived on the scene.
So exactly what percentage of worlds fit this description, and what is your sample size? The above notions are all simply speculations, but they're a lot more sophisticated speculations than "1 non-gas-giant planet of 5 supports life, therefore 20% of the non-gas giant planets support life", or intelligent life has appeared on this world after it is half its projected existence, therefore half of all worlds supporting life have intelligent life".
Hopefully, this next Darwinian scythe from the icehouse-to-greenhouse-to-icehouse cycle we are currently on will result in smarter humans, and if not, then smarter bears or cockroaches. But not birds. I can't stand birds, as they crap all over my car.
These arguments PROVE (OK, strongly hint at) that there's no intelligent life on this world.
When there is insufficient information to state anything about a solution set, intelligent beings do not extrapolate an answer to nine decimal places.
There's a glaring flaw in this theory that's obvious to even me: It doesn't include intraspecies conflict. Subgroups within humanity are going to continue to compete with each other; it's called "war," along with less drastic forms of competition. As long as even a single individual has the ability to dominate another individual, there will be a reason to continue to develop technology, if only to provide more effective means to destroy each other. Just look around you today if you think there's no reason to continue improving our technology...
The question then becomes more a matter of whether or not we develop mechanisms so powerful, that the destruction of the species is inevitable or not. For example, if energy becomes so plentiful, a single individual can destroy the entire planet, before we've managed to move beyond it. Since single individuals are not necessarily rational, such a capability is inevitably abused.