According to the New York Times, two scientists have released a book stating that life outside of our solar system is a lot more unlikely than we had hoped. Dr. Peter D. Ward, a paleontologist from the University of Washington, and Dr. Donald C. Brownlee, a noted astronomer, member of the National Academy of Sciences and chief scientist of NASA’s Stardust mission to capture interstellar dust, say that:
Our type of sun is not as common as we had hoped.
We are lucky to have a moon large enough and in a stable enough orbit to stableize the tendancies of the planet to shift the axis more often and more violently than it has already.
We have a planet in a stable orbit the size of Jupiter to attract most meteors away from us.
Our position in the galaxy is good for the propogation of life. If you get too close to the center, where the stars are hotter and denser, the killing waves of x-rays, gamma rays, and ionizing radiation would just about cook any primeordial soup you plan on cooking. On the fringes of the galaxy, according to analysis of the starlight, are poor in such elements as magnesiun and silicon, which are prerequisites to the formation of of planets which can form gravities that can retain seas and atmospheres that have plate tectonics, which are powered mostly by the heat of raioactive decay. In other words, either too much time in the microwave, or too little.
Our plantet has an orbit that keeps it exactly the right distance from the sun to ensure that the water remains liquid, not vapor or ice.
Enough carbon to ensure the development of life, but not so much that a “greenhouse” effect occurs, like in the case of Venus.
In other words, we have gone from looking for a needle in a haystack, to looking for a golden needle pointing exactly north by northwest with the King James version of the Bible etched on the head.
Well, I haven’t seen the book, so I’m responding to slythe’s setting forth of Ward’s and Brownlee’s arguments here. Given that, however:
[list=1][li]What is “our type of sun” supposed to cover? Single G2 dwarfs?[/li][li]We can’t say that we are “lucky”, exactly. No other terrestrial planet in our solar system has any moon to speak of (Mercury and Venus, nada; for Mars, Phobos and Deimos can be written off to a good first approximation). Still, that might mean that terrestrial planets should be neglected in favor of large moons of jovians and superjovians.[/li][li]Maybe. See above.[/li][li]A bit of “bird reasoning” (“Every habitable planet must have a high-pressure, oxygen-rich atmosphere so that the inhabitants can fly, just like us birds.”). Given that it seems increasingly likely that the earliest prebiotic chemicals are introduced by comets and the meteoroids they form upon disintegrate, a high-radiation background may be just what is needed to form these chemicals, away from the shielding atmospheres and magnetic fields of planets. What we really need on this (and all other points) is some research mapping out concentration of organics in dust clouds vs. distance from the galatic core.[/li][li]At the periphery, which is largely old Pop II dwarfs (I believe that the terminology has changed now, but that’s what it was thirty years ago), yes, metallicity (the presence of any element heavier than helium) is low. OTOH, if we assume that size of terrestrial planets is proportional to metallicity, we get any star above 0.1 (relative to Sol) with Mars-sized planets; these are stable against loss of atmosphere to space (unless the temperature is already so high that we can write off the possibility of life) for hundreds of millions to billions of years.[/li][li]Ward and Brownlee have just thrown out every variant of the Gaia hypothesis down to medium-weak.[/li][li]Same as above. Incidentally, Venus and Earth appear to have the same amount of carbon. The difference is that Venus’s is almost all in the atmosphere, whilst Earth’s is almost all in limestone and other insoluble carbonates.[/list=1][/li]
“I don’t just want you to feel envy. I want you to suffer, I want you to bleed, I want you to die a little bit each day. And I want you to thank me for it.” – What “Let’s just be friends” really means
Besides that, haven’t years of watching Star Trek taught us anything? Life doesn’t have to be carbon-based, needs water, etc. You could have a silicon-based entity. Life could be created in other conditions, just not life similar to ours.
OK, I started out being slightly facetious, but the point still stands.
“The large print givith, and the small print taketh away.”
Tom Waites, “Step Right Up”
The universe is pretty darn big though. While Earth may never encounter an alien race, you just logically have to think that there is other life, intelligent at that, out there somewhere… so what if its in another Galaxy 100 trillion light-years away?
I am trying to remember one of those shows where the subject was UFOs or alien civilizations or whatever… anyway, some math geek had some kind of formula that was using odds as one way of approximating other civilizations.
Out of a million stars, one has a planet or planets.
Out of a million of those planets, one has the capability to support life.
Out of a million of life capable planets, on has life. (primordial ooze, plants, sigle-celled organisims, etc.)
Out of a million planets that have life, one has intelligent life. (human, some animals)
Then the number was like 10,000 planets that could have intelligent life on them… I guess this is due to the astronomically huge numbers of stars that are out there, and its a pretty safe bet we have only scratched the surface even with the Hubble telescope showing us thousands of far-off Galaxies.
“Wow! Spider-Man! Are you really friends with the X-men?” "Not since Cyclops tried to use my viewmaster."
(Marvel Team Up #1)
Incidentally, take a look at Robert Zubrin’s Entering Space. It’s a great discussion of the various stages of space exploration by a widely-respected scientist.
The Drake equation. Developed by Dr Frank Drake of the SETI Institute when working at the National Radio Astronomy Observatory, Green Bank, West Virginia. (Thus I’ve also seen it called the Green Bank Formula.) http://www.seti-inst.edu/science/drake-bg.html
Since there’s no firm numbers for any of the factors, you can reasonably massage the numbers to give anything from 1 - us - to tens of thousands.
Carl Sagan used a similar equation in “Cosmos” and came up with “6” as the number of planets in the universe with intelligent life.
Also, Clifford Simak’s “If the Stars Are Gods” had an interesting philosophy–specifically that “life” on other planets might be so alien to our preconceptions that we might not even recognize it as “life.”
Yeah, the terminology has changed. They’re called either “thick galactic disk population” stars, “intermediate galactic population” stars, or “galactic halo population” stars, depending on: how far away they are from the plane of the galaxy, how high the “Z” component of their velocity vectors are, and how deficient they are in heavy elements.
Thanks heaps for the assist Tengu! I was trying to recall from what was probably a year old memory, so it was not spot-on but Tengus link explains all.
Time to perform memory exercises…
“DRAKE equation… DRAKE equation…”
“Wow! Spider-Man! Are you really friends with the X-men?” "Not since Cyclops tried to use my viewmaster."
(Marvel Team Up #1)
Right now, trying to look for life outside of our galaxy is a moot point. It takes light long enough to reach us from the closest star, so lets not even pretend that there is a possibility of life visiting us from another galaxy. BTW, for a planet to have a lifeform advanced enough to travel through space…no, strike that.
For a planet to have a lifeform advanced enough to develop a tool-using society, it stands to reason that other forms of life must exist on the same planet. No competition=no advancement of species. So now we are looking for a planet circling the sun at just the right distance to ensure a steady state for most of the water supply, with either an incredibly steady orbit or a large moon to act as a stableizing force, a large planet near-by to divert most meteors, a minimum of stellar radiation, the right elements to support plant life, and an enviroment that would support multiple forms of life.
As far as “other” forms of life go, Star Trek has been out since the sixties, science fiction has played with the idea since the turn of the century, but has anyone developed a silicon-based life form yet, supposedly the simplest and most talked-about alternative discussed?
** CNRS Space Study Center for Radiation in Toulouse, France
** says
The astronomical data has tilted the evidence balance in favor of hypotheses that describe the spontaneous generation of “organic” compounds in space. While it still is not unarguable that the emission spectra are only from carbon ions or soot particles, some of the scientists investigating the matter from the laboratory end of things feel that direct corroboration from emission spectra created here on Earth will pretty much settle the matter.
The generation of the precursor chemicals of life might be a non-unique event, if the information being discussed is accurate. It is a lot of steps short of life, however. The inclusion of PAHs in accretion disks around newly forming planets might well be one of the requirements for life, or one of the steps along the way.
<P ALIGN=“CENTER”> ** Tris** </P>
If a lunatic scribbles a jumble of mathematical symbols it does not follow that the writing means anything merely because to the inexpert eye it is indistinguishable from higher mathematics. – **Eric Temple Bell, **
Does the fact that science has not developed any examples of carbon-based life mean that it doesn’t exist? Tsk, tsk, Slythe, you generally do better than this.
<P ALIGN=“CENTER”> Tris </P> ------------------
On two occasions I have been asked [by members of Parliament], ‘Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?’ I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. – **Charles Babbage, ** (1792-1871)
Tsk, tsk Trisk.
It’s not up to me to disprove such outlandish theories, it’s up to you to prove them. Down here on Earth, we call this process Science.
Krispy, if there is no competition, there is no need whatsoever for a species to do anything be eat, grow fat, and die. Not my law, Nature’s. If you know of a different set of rules, would you mind posting them?
Folks, what is so difficult with dealing with the fact that we won the great Universal Lottery? Somebody had to win eventually, and if it was some other species, I guess they would be asking the same questions. Go figure.
Well, science, the one without the capital letter, and the italics, includes a concept called a hypothesis. It is the beginning of science, the first step in the method. By the way, a hypothesis is . . . are you ready for it? . . . Hypothetical. Proof is not the next step. Examination is the next step. If you discard every hypothesis before it is examined simply because it has not been proven, then I must believe that * Science * is a rather narrowly circumscribed subset of science.
However, acceptability to the arcane criteria of * Science * was not the part I objected to in your comment. Carbon might not be the only chemical basis for life. That is not an outlandish theory, it is simply the absence of the outlandish theory that only Carbon can be the chemical basis of life. I am willing to consider the hypothesis, however, without proof, since science allows much more wide spread sources of new knowledge than does your * Science *. You contention that the failure * Science * to produce non Carbon life was in some way a valid refutation of the hypothesis assumes that your carbon only limits to life are inherently proven by this * Science * you find so compelling.
<P ALIGN=“CENTER”> Tris </P>
We learn more by looking for the answer to a question and not finding it than we do from learning the answer itself.
– **Lloyd Alexander **
