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Earth-Like Planets In Our Neighborhood
goran72 sends in a story out of the Chicago AAAS meeting contending that Earth-like planets with life-sustaining conditions may be spinning around stars in our galactic neighborhood — we just haven't found them yet. "'So I think there is a very good chance that we will find some Earth-like planets within 10, 20 or 30 light years of the Sun,' astrophysicist [Alan Boss]... told his AAAS colleagues meeting here since Thursday. ... The images from those new planets, he added, should identify 'light from their atmosphere and tell us if they have perhaps methane and oxygen. That will be pretty strong proof they are not only habitable but actually are inhabited. I am not talking about a planet with intelligence on it. I simply say if you have a habitable world. ... Sitting there, with the right temperature with water for a billion years, something is going to come out of it. At least we will have microbes,' said Boss."
The human body contains about 100g of DNA. You're saying about 2E15 grams, or 20 trillion human body's worth, of DNA is not only released into the atmosphere but then escapes the earths gravitational pull and enters interplanetary space.
Sounds unlikely.
... exchange communication once every 10 years,...
We could give them, say, the entirety of Wikipedia, and they could give us their equivalent. Write up a "rosetta stone" with a bunch of pictorial/mathematical representations of words, and so on. Probably doable. Conversation back and forth will seem frustratingly slow, but there's no limit to the amount of info that can be streamed across.
Mind you the chances that we will be in the near vicinity of a civilization that communicates by radio waves that we can pick up is possibly quite slim- we've only been doing it for less than a hundred years. They could be in our equivalent of 1750 and we'd never hear a peep.
I would think that we wouldn't just send "Hi" and wait for a response. I think we would constantly be sending them information and let them learn what we are sending. We would hope they would do something similar.
Man, you ARE pessimistic. As well as wrong.
Once it became known that a civilization existed in a particular star system... and they knew about us... communication could be continuous both ways, not just back-and-forth like a walkie talkie every 10 years.
Starting with math: primary numbers, Fibonnacci sequence and other natural patterns, on to addition, subtraction, etc... then to logical propositions and conclusions... we could communicate an entire language and maybe even a couple of encyclopedias in the time it took for ONE 10-year round trip of communication.
And with ion drives, or Bussard ramjets (especially if they are Pellegrino-style vehicles that pull instead of push), maybe we could get there in, say, 50 years or so. And spend most of that time in something like cold sleep. There have been advances in that direction, too. Do we have the technology to do this? No. But we might in 10 years, or 20.
Of course, we would have to decide what and how much to send in our communications. There could be very real danger. I do not think most people understand just how deadly we (and by implication, they) could be, given enough time and effort, even to a civilization light-years away.
"Flying to Valhalla", by Charles Pellegrino, is a work of fiction. It is the book in which he introduced a totally new (but perfectly sound from an engineering standpoint) style of interstellar ship construction. As controversial as Pellegrino is as a person, there is no doubt that he is, as the saying goes, "wicked smart". There are some very plausible cautions in his book.
All right, What The Hell?
For a planet to "shed" anything except perhaps hydrogen or helium, that stuff has to overcome escape velocity, which (until rockets were invented in the 20th century), requires an (volcano or meteorite) that would incinerate any complex organic compounds and render DNA a fine ash.
Plus, Google will tell you that the following comes out to 44%, as an above poster already said:
(4 billion years) * (2 billion tons per day) / (5.9736Ã--10^24 kg) in percent
Less than 1% of Earth's mass is at a temperature that even permits life to exist. As for the part that actually consists of life, you can measure it in parts per million and still need scientific notation.
We could give them, say, the entirety of Wikipedia
REPORT ON THE INGREDIENTS OF THE EARTH'S CIVILIZATION AS SEEN FROM THE "WIKIPEDIA" SENT BY HUMANS * 20% ---- Elitist mod-trolls * 30% ---- Politics (a.k.a. sheeple herding) * 35% ---- Religion-like (i.e. spirituals, rituals, TV, Paris Hilton, Web 2.0, Slashdot, pr0n, etc) * 15% ---- Obsolete knowledge known as "science" and/or "technology" CONCLUSION Humans make good material for Soylent Green.
Colorless green Cthulhu waits dreaming furiously.
CONCLUSION: Mostly harmless
While it initially appears that you would be traveling faster than the speed of light, you indeed are not... when you reach relativistic speeds space itself compresses, so from your perspective the distance traveled between two points is less than the distance as measured from a resting observer. End result your measured velocity is less than C. To the resting observer, you travel the larger distance, but time is dilated such that your velocity is lower than C. Since the apparent distance between the origin and the destination is decreased, the amount of time it takes light to make the same journey would be less than the amount of time it takes you. In fact, from your perspective light is still traveling... at the speed of light.
Now, to take the concept to the ultimate (but unreachable) conclusion: to reach such a velocity that an outside observer would record you as moving equal to the speed of light: To the traveler it would seem as if there was actually no distance traveled, and the journey took no time at all. What the traveler would observe is space and time folded between the origin and the destination... for a 10 light year journey, you would instantly travel to the destination, but 10 years later. The return trip would also be instantaneous, but 20 years would have elapsed at home since you have left. Thus, the speed of light is not violated. However, to cut your travel time to zero in a Newtonian framework, you would need to reach infinite speed in zero time, which would require infinite acceleration, which would in turn require infinite energy. That is impossible, so an object with a resting mass cannot travel at the speed of light (or beyond.) But you still have to take into account the fact that at relativistic speeds, space constricts while time dilates, allowing for what on the surface appears to be traveling faster than the speed of light, but actually is not.
I'll never make that mistake again, reading the experts' opinions. - Feynman