Posted on 04/05/2005 9:36:50 AM PDT by LibWhacker
The Universe could host billions of Earths
British researchers are more confident than ever that there are "Earths" out there waiting to be discovered.
The scientists say perhaps a half of all the known planetary systems today could be harbouring habitable worlds.
It must be said most of these systems are strange places where supergiant planets orbit close in to their stars.
But Barrie Jones and colleagues say their modelling work suggests that even with this oddness, there should be room for small rocky planets.
The Open University team presented its ideas here at the UK National Astronomy Meeting on Tuesday.
They extend recent and previously published theoretical work, "putting it on a firmer modelling basis," Professor Jones told the BBC News website.
The research calculates the likely number of Earths out there, based on what we know about how planets form and the conditions needed for life - in particular, the requirement to sit in the part of a solar system that is neither too hot for liquid water, nor too cold.
'Disaster' area
"The conclusions haven't changed, I'm pleased to say. Roughly half the systems out there could have Earths in their habitable zones today and have been there long enough for life to develop," Jones added.
The limitations of current telescope technology make it extremely difficult to view so-called extrasolar planets directly.
Astronomers have therefore made most of their detections indirectly - by finding stars that appear to "wobble" under the gravitational tug of what must be nearby, very large planets.
The technique has the bias of only showing up apparently bizarre systems - where planets that are sometimes many times the mass of our own Jupiter circle their stars in orbits that are smaller than Mercury's.
And this presents a problem because current thinking holds that these huge Jupiters probably formed some way out from their stars before migrating inwards. And if they did that, the chances are they would have destroyed all in their path, including any fledging Earths.
"We've now got some simple rules for establishing how far these disaster zones extend," explained Professor Jones.
Moving zones
Encouragingly, his team finds there is plenty room and time for Earths to evolve.
"At the stage these great giants sweep through, the Earths are not formed - they are still smallish planetary embryos. They get scattered but the simulations show enough material remains that Earths can form after the migration of the great giants has taken place."
The team found about half of the known exoplanetary systems offer a safe haven for a period extending from the present into the past that is at least long enough for life to have developed on any such planets.
The situation is complicated slightly by the fact that the habitable zone migrates outwards as the star ages, and in some cases this changes the potential for life to evolve.
Thus, in some cases a safe haven might have been available only in the past, while in other cases it might exist only in the future.
These scenarios of past extinction and future birth increase to about two-thirds the proportion of the known exoplanetary systems that are potentially habitable at some time during the main-sequence lifetime of their central star.
The research by Barrie Jones, Nick Sleep, and David Underwood has been published in Astrophysical Journal.
I don't discount the possibility that it's an urban legend, but given the fact that over just a few decades the amount of radio energy has increased so much I'd expect it to be noticed, IF it's reached any other world with the technology that could see it.
Not quite. Anything below 1GHz gets attenuated pretty quickly. Our TV broadcasts would not even be noticed as far out as the nearest star. What is worse is that interstellar scintillation pretty much destroys any of the modulation characteristics leaving only the narrowband carrier. This is why SETI looks for narrowband carriers sans modulation. So "I Love Lucy" is going to the stars (except as microwave digital streams that are uplinked to the TV satellites only).
Dimensional travellers, rather than "life on other planets"..
The "sleeping prophet", Edgar Cayce claimed in one of his "sessions" that humanity would indeed, meet intelligent life some day..
But it would be 10's of thousands of years from now, and they would be so far beyond us that we would consider them as god-like, and we would be completely beyond their notice..
That's pretty humiliating, isn't it?
To finally find life in the universe and find out you are no more than ants beneath their feet?
Great tag-line, by the way..
Or as Captain Picard observed, "Any tecnology sufficiently advanced beyond our own would be indistinguishable from magic."
Being a computer geek, I prefer the corrolary that any technology that is distinguishable from magic is not sufficiently advanced.
placemarker
Think!
If you were from a technologically advanced civilzation many, many light years distant from here, would you waste you time on this violent collection of scientific wannabes, when in all probablilty there's so much more to be had out there?
How could you trust a "civilization" that is brutal to it's own?
How could you approach a people who have seen fit to irridate their own planet - not just once, but many times?
How comfortable could you feel with an ignorant mass of collected races that seemingly have been thrown together haphazardly, and can't find it in themselves to get along?
How confident would you be with a world that has just scratched the surface of scientific possibilities and whose first option to your visit is more likely than not going to be militaristic?
With each passing year I become more and more convinced we live in a really bad galactic neighborhood, and until such time as we get our sh*t together, we won't be graced with a visit from these guys any time soon.
And in passing, I don't think warp technology is the answer to interstellar apace travel. At some point it might serve as a semi-useful bridge technology, but I really think they'd use something else more efficient.
Just my thoughts...
CA....
"The universe is one big place"
I don't think many people have a good grasp of what a light year is.
How much would a spaceship cost (even a speed of light job) and a trip? Would an alien society be willing to pay for that? For what, to experiment on humans? GMAB.
I could see satellite travelers, broadcasting, but it would take many, many years for one to get anywhere distant from its source.
Absolutely! :-)
or maybe Alien Boy Scouts, err Person Scouts.
If Pickard said it, he got it from Arthur Clarke.
"Any sufficiently advanced technology is indistinguishable from magic." - Arthur C. Clarke, Profiles of The Future, 1961.
Or maybe the opposite is true. We are the peaceful, ecologically sensitive ones that ate technologically superior by comparison. One civillization must be the most advanced. It could be us.
Oh, they're plenty advanced. They just can't afford the phone bill.
Therefore, no other earths can exist.
Plenty of "Earths", little intelligent life.
I watch Stargate, I knew that!
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