Earth: no longer the lonely planet

SpaceRef ^ | 9/26/03

[Stultis]

Good point. And I would add that, given the huge size of the galaxy, not to mention our location in a peripheral area thereof, there could be thousands and thousands of civilizations in the Galaxy, but still so disperse that the chance of ever detecting them would be small.

IOW, even if there is a great deal of life in the galaxy it doesn't mean that The Earth won't remain, effectively, "lonely".

[ghostrider]

I said with billions and billions of planets, that the prospects for extraterrestrial life are fascinating. I said nothing about looking for life on one planet.

[Stultis]

I tend to agree. As I was just saying (typing) and as your analogy suggests, the probability of finding extraterrestrial life depends not on the absolutely number of planets that have life, but on the density of their distribution (and of course the percentage that acheive intelligence, techonology and the propensity to transmit detectable signals).

I'm a skeptic, frankly. I don't think we will detect extraterrestrial life anytime soon (say within the next hundred years). In fact, and of course I'm just guessing, I don't think the probability is particularly good that we will discover it in the next thousand years, even though I also tend to think that extraterrestrial life does exist.

[LiteKeeper]

INTREP

[hosepipe]

Judgeing from earths world history.. a planet with intelligent life on it is still unknown in this universe..

Question... and would we know intelligence if we saw it..?

[Wonder Warthog]

"Just ask Colonel Hammond."

Uh, that's GENERAL Hammond. The Colonel is O'Neal.

[<1/1,000,000th%]

"Given that there are about 400 billion stars in our Galaxy alone, it means there could be up to 400 billion stars with planets," he says.

Hey! The galaxy grew again!

[hardhead]

I think it will be within 10 years! And, I believe there will be proof of the existence of extra-solar life within 15.

[ChadGore]

Re: "well now we know where James Carville come from"

Qball phone home!

[RightWhale]

we will find a Earth like planet in 20 - 30 years.

Kidding, right? You can't even find a great apartment in 20-30 years.

Here's what will happen: we will find a planet close enough so that we can transform it to a base condition we like. This transformation will take a really long time, a million years just to pick a number. But we will find a close enough planet in 20-30 years, it just won't be what Joe Sixpack would call earthlike.

[Prodigal Son]

but still so disperse that the chance of ever detecting them would be small.

Ever is a big word.

[BlazingArizona]

Which makes me question this whole "25% of stars have planets" thing. In order to detect an alleged planet, the planet has to pass between us and the remote star - that is, transit across the face of the star from our point of view. Now, think about that. What if we're not aligned with the ecliptic of that system. We'd never even see a single planet yet the system may have many.

The problem is this: currently, we detect extrasolar planets by watching for stars that wobble slightly when orbited by a close-by dark object. Ths technique allows us to find planets anywhere in the sky, but only planets large enough to cause their star to wobble. If we could look at our own solar system from a distance, we would find it difficult to even detect Jupiter with this method. This is why, although we're seeing lots of planets out there, we can only see very large ones.

Using the transit method would allow us to see much smaller planets. Although to use the transit method we are limited to stars whose planetary orbit planes happen to coincide with our line of sight, the idea behind Kepler is that if we survey a sufficiently large number of stars, we will find a few that happen to present at exactly the right angle. From these, we can then estimate how many planets there are in the sky.

[LibKill]

Are you kidding?
Haven't you heard of PN3217? If we get the right coordinates we can visit them all.

Just ask Colonel Hammond.

You tell Colonel Hammond that I don't want to go to abydos! :)

[Wonder Warthog]

Geez--this pic of Carville is HILARIOUS (and an excellent characterization, too). Whoever dreamed it up is a genius!!

[Rudder]

"...25 per cent of Sun-like stars have planets."

At first measurement, there were only 40 billion candidates and with this article the estimate has jumped by 60 billion and, as techniques refine there may be 400 billion "sun-like stars."

All the while, "...if the Sun were one of the stars being monitored, we still wouldn't have detected any planets around it."

Thus, even though we have tremendously increased the odds of finding more planets in the universe , we can't find the one planet that we know has intelligent life.

We are reduced to looking where the light is best for something we have proven we cannot find.

[Tench_Coxe]

Imagine if this is the first intelligent race we find ( pinging all Larry Niven fans ):

[irv]

You tell Colonel Hammond that I don't want to go to abydos!

He's been a general for a number of years now. And really, I'll go anywhere he wants me to. Just so long as he sends me with a zat -- and Major Carter.

[friendly]

Please put me on your ping list.

I believe in the Rare Earth Hypothesis, which includes the prediction that the skies are filled with planets teeming with life.

This is however only primitive types of life, such as dominated the earth for several billion years, up until (comparatively) very recently.

[Maurice Tift]

Define "Earth-like."

I think Earth-like means a planet that looks exactly like Earth with exact replicas of all the people here with the exception of James Carville and Paul Begala.

[Alamo-Girl]

Thank you so much for the heads up!

This is verrry interesting in that it is the polar opposite of the article which formed the basis for the now pulled thread “Solar System Formation.” That base article is here: http://xxx.lanl.gov/PS_cache/astro-ph/pdf/0207/0207536.pdf

In that article, the scientists create an improbable scenario for planet formation which must begin with a large surface area of one kilometer. That would mean fewer planets ought to be expected, fewer still of our type. On the pulled thread I asked whether dark energy should have been considered. I pose the question again here.

I believe dark energy ought to be relevant to planet formation in that negative gravity would create acceleration in every direction, causing additional pressure on particles in the intervening space to bind. It seems to me this additional pressure would be actualized as heat in the particles, thus providing for binding of particles smaller than a kilometer.

If dark energy is negative gravity, then it would not exist in the presence of positive gravity and thus could not be measured in local space laboratory experiments. It would have to be inferred from deep space observations, like we infer black holes from other evidence.

My deduction is based on the "duality" between gravity and space/time. Positive gravity should be visualized as an indentation of space/time causing approaching objects to orbit and spin downwards into the indentation. And conversely, objects within the indentation much achieve an escape velocity to get outside the horizon of its space/time geometric effect.

Therefore, if dark energy is negative gravity the reverse would be true. It would be an outdent of space/time causing objects in its horizon to be repelled - or accelerated. Like the positive gravity indentation, the outdent would create acceleration in every direction.

The implication of this thought experiment is that negative gravity, like positive gravity, would be be very small compared to the other fields (electromagnetic, strong and weak atomic) --- but would accumulate over distance.

Consequently, I would expect planetary formulation in environments which would not begin with one kilometer sized planetisimals to infer the existence and effect of intervening dark energy. Dark energy accounts for 73% of the mass of the universe.