The Origins of Life

Great Debates
61

Speculation is a great game, and some interesting ideas can come from it.

I am not investing anything into panspermia without some evidence. Within the next ten years, we should have more samples of extraterrestrial material. If there is no sign of encysted bacteria in anything we can find near Earth, then I would have to say that panspermia belongs with the other neat ideas that didn’t pan out. If we find the remains of Earth bacteria in lunar soil, or in a comet, or even in the dust and crap that is gravitationally associated with Earth, then we will have something to work with.

Concentrations of bacteria should be highest closest to the source, so collection of orbital dust should be able to settle this quickly.

62

Excellent! I agree. The topic warrants investigation. Direct evidence shoud be sought.

If the idea were disimissed out of hand perhaps we wouldn’t seek this evidence, and miss out on something interesting.

I have no investment one way or the other. I just want to know. Yes, speculation is fun.

On another note, I was unable to produce a collaborating cite for Zubrin’s 230 million year Permian salt assertion.

I wonder now if he was in error, and had misinterpreted bacteria thriving in Permian salt domes as Dr. F postulates.

I will just go into Waldenbooks

“Hi, I’d like to return this book. one of the facts is broken.”

63

Re: orbital dust collection.

just occured to me that this wouldn’t necessarily prove anything.

With all the manmade artifacts in orbit. and the Soviets and our habit of disposing of bodily waste into the vacuum, most of near earth space probably has more bacteria than a Times Square toilet.

64

Okay, so we send the dust-mop probe on a long loop, possibly even through the trojan points on Earth’s orbit. We don’t deploy the collectors until it is past lunar distance, and have it shut down before it returns.

We may not even need to return the samples. A little electrically heated “greenhouse” and a few dozen sample media could do the trick. We could still miss everything biological, if we don’t supply the right nutrients. I have heard that it is estimated that up to 90% of all Earthly bacteria are unknown because they won’t grow in standard media.

Time to make a grant proposal to NASA…

Dr. Fidelius, Charlatan
Associate Curator Anomalous Paleontology, Miskatonic University
Zu diesem Projekt ist derzeit noch kein Abstract verfügbar.

65

I don’t know if NASA can spare any funds from their exhaustive studies of microgravity on elderly Congressman in order to pursue such trivial questions as the origins of life.

66

Would it be enough if they just got rid of those Evil Nazi Groundhogs?

67

Damn you mrblue.

Now I keep hearing:

Evil Nazi Groundhogs…in SPAAAAACCCCCEEEEE!!!

Okay, so I’m not really hearing them, you understand…

68

Shhhh. You’ll give away my secret identity.

Something very very interesting.

I was dismayed that I seemed to be winning this argument (in my mind anyway,) and that nobody was able (or bothered) to tear apart my numbers (if I’m a winning a science argument there is something very badly wrong, since I am bad science personified.)

So anyway I checked out the link Dr. Fidelius provided and said what the hell, and e-mailed Jon Richards at Cambridge my inverse panspermia probability analysis. I was curious to see how he would react to my unassailable logic.

Today I received the Gentleman’s reply along with a request for permission to pass it on for further study.

I could barely contain my glee!!!

ME!!! Humble message board poster, and self-proclaimed master of bad science had achieved a major breakthrough that could change our understanding of life as we know it! This is especially amazing since I went to College in New Orleans and squandered my education drinking beer and chasing women.

Unfortunately, the next part of the email contained his critique.

Never before in my life have I seen an argument disected so thoroughly, ripped apart and mecilessly savaged, piece by bloody piece. Not only that, but it was absolutely hilarious! I almost fell off my chair.

I am surprised and impressed by this man’s willingness to take his valuable time and seriously critique an argument written by a pretender such as myself. He also suggested that I should reply to his points. Oddly enough he’s going to actually consider some of my points, and have others (with my permission review it too.)

I have asked his permission to post his comments here, and will if he agrees.

To have your arguments ripped apart is unpleasent. To have your arguments ripped apart by a master is a privilege. To have that master tell you that it’s conceivable that their might be the faintest germ of worth in the argument is heaven.

I am so full of myself right now, its not even funny. I think I shall go and try to ressurect Lamarck again! (just kidding)

69

Hey Scylla, that’s great! Let us know what happens.

P.S. The first time someone rips your thoughts to shreds it can be a humbling (and humiliating) experience, but it’s all part of the regular scrutinizing process in science. Come to think of it, it’s not unlike having to defend yourself in GD. :wink:

70

It’s more like the time I had the opportunity to play a set of tennis against Ile Nastasse.

I knew I was gonna get ripped apart and not even get a game (I was right, hardly a point.)

It was just the fun of being on the court with him. I love having my ideas ripped apart by experts!

My ideas are currently being reviewed by experts at Cambridge… …So There!

71

Well, I was still kind of interested in discussing the matter. I have some trouble with the hypothesis over it’s entire breadth, rather than it’s individual hurdles. The hypothesis cannot survive under the principle of least assumptions. Occam’s razor slices this one to ribbons.

You see, it is possible that a sample of organic material might be ejected from a planet by meteoric impact. It is not impossible that it would survive. It is also not impossible that such a chunk of rock with living material might eventually ride the solar wind across the vast distances of interstellar space. It is not impossible that it might join in on accretion of matter around a new sun. It could survive the fiery pinball dance of planetary creation, and even the massive forces of planetefall, with or without atmospheric cushioning. It is not impossible that the now frigid ancient mote of life might be still viable. It is even within the realm of possibility that it might be simultaneously freed from its hardy encapsulation, and be surrounded by chemical environments similar to the ones for which it evolved.

Yes, the individual events are possible. But the hypothesis does not stand on the possibility of the individual event. It must stand on the likelihood of the process as a whole existing over the entire galaxy. Suppose the progenitor planet has a history similar to our own, not denying that it was the original home, it must then have an abiogenesis event. That event must wait for the planet to cool, somewhat. Since all life in the galaxy now must have come from that planet, all of life’s lineage must have been ejected from it, or from it and some number of others. What percent of bacteria survive explosions sufficient to create escape velocities?

The now free faring life form must survive space. What percent of bacteria survive exposure to space conditions for a hundred thousand years? A hundred thousand years pass, and our survivors are cast out by the stellar wind. A quarter of a billion years goes by. What percent of those bacteria survive now? The icy chunk of life cells and cosmic detritus plunges into the stellar nursery to join its new planet’s system. What percent of the cells are in the ecliptic? What percent are not swept up by the gas giants, or the new sun? What percent land on still glowing balls of Iron and silicon? What percent are burned up in reentry? What percent land in the wrong epoch geologically?

No single step can be categorically denied any possibility. But you are asking not for one occurrence, but billions of occurrences of events which each must kill the overwhelming majority of any organism similar to Earth’s extremeophile anerobic bacteria. And this is just the first generation. To be at all likely, the numbers of bacteria must be huge, truly and literally astronomic, and a very high number of iterations is essential for the distances we can observe.

Now consider that the areas where life is developed are not likely to be randomly near or far from the places where planets are forming. Quite the contrary, it is more likely that planetary systems near each other are of similar age. New systems would be farther off. Consider this, as well, the life motes are not directed, they are spreading by diffusion. Grind up the entire planet Earth, and spread it out over the volume of only 10 parsecs, and you don’t have even a detectable presence. You certainly don’t have enough life spores to consider it as a likely source of infection, even if every mote is immortal. A hundred parsecs makes the problem ten thousand times worse. That’s just local. Now lets consider long distances.

The idea is not impossible. But it begins to be a whole lot of improbable, when you consider that all this stuff has to happen so early in the history of the galaxy that the multiple iterations of seeding events have enough time to spread out to the new homes. Each trip takes a quarter of a billion years, not counting time waiting for the coincidences of collision in a ten light year sphere. Then a half a billion years to saturate the new environment. That gives you only ten generations of seeding in all galactic history if your billiard shots are perfect, and perfectly timed. One failure, and the whole thing stops.

Now look at that list of not impossible things you want to believe. Want to bet on eight straight 100% wins? How much cash you got?
<P ALIGN=“CENTER”>Tris</P>

And who can doubt that it will lead to the worst disorders when minds created free by God are compelled to submit slavishly to an outside will?
– **Galileo Galilei, ** (1564 - 1642)

72

Good points. I have an idea.

Lets create an equation for the probability of an inverse panspermic event occuring within a billion year period.

I would guess the following variables need to be included:

A=the number of bacterial “units” leaving the solar system per dinosaur killer tupe meteoric event. This would include tiny naked spores as well as chunks encased in rock.

b=the number of meteoric events per billion years. How does 40 sound?

c=the average viability in years of an interstellar unit.

d=the average speed of a unit

e=the number of stars per light year. I still think that .5 is pretty good.

f=the percentage of stars which could potentially support life.

g=the chances of a unit getting captured by a solar system once it passed within a 1/2 light year of it.

h=the chances of a unit landing and distributing itself throughout a suitable planet through reproduction once it was captured by a suitable system.

I=How long H takes.

Anybody want to take a crack at putting those together?

73

**Good points. I have an idea.

Lets create an equation for the probability of an inverse panspermic event occuring within a billion year period.

I would guess the following variables need to be included: **
[/QUOTE]

A=the number of bacterial “units” leaving the solar system per dinosaur killer tupe meteoric event. This would include tiny naked spores as well as chunks encased in rock.

Let’s make this one x, and solve for it, at the end. So, x is the amount of matter carrying surviving life, after this huge asteroid impact. We will come back to reasonable estimates of that percentage, and magnitude later.

b=the number of meteoric events per billion years. How does 40 sound?

Fine, but lets make it 100 to be sure we are being optimistic at this end. (The real bad news comes later.)

x*10[sup]2[/sup] units in orbit in the genesis system.

c=the average viability in years of an interstellar unit.

Average is not what we are going to need, but rather a number to estimate our population. Let’s assume a mortality rate of 50 percent per million years. (generous, I think) for the entire population in space.

d=the average speed of a unit

This one has to be escape velocity for the outer system, but it seems unlikely that it would be any higher than a minimal escape trajectory, since it only happens by chance. Lets assume it can’t be any greater than the orbital velocity of the planet, rotated to a vector directly out from its primary, since we really have no numbers to crunch. Earth moves about 10[sup]9th[/sup] Kilometers per year around the sun. Aim that straight out. Again, we are being deliberately generous.

e=the number of stars per light year. I still think that .5 is pretty good.

That figure is really too good. An average distance of 5 light years separates stars in our galaxy. To be reasonable, twice that distance would be a lower limit on our thought problem. This is where my optimism hits a limit. It does us very little good to hit a planet late in the system’s life or too early. The only place we had in our solar system that could be a good landing spot was Earth, and only at the time when it had its reducing atmosphere, but had lost enough hydrogen to avoid being a heat well, like Venus. The fertile ground is not too far from the stellar nursery, but out of the clouds of the original accretion disk. The nearest stellar nursery to us now is in Orion, which is 1500 light years away. I am willing to compromise, but only down to 10 light years radius from the primary.

f=the percentage of stars which could potentially support life.

Actually, what we need is how many planets are likely to be able to support life, at any particular star. Observation gives us 9 major bodies, and some minor, with one supporting life, that rate is about 10 percent. Lets call it one in any star system, again being generous.

g=the chances of a unit getting captured by a solar system once it passed within a 1/2 light year of it.

Here is where our first real bad news hits. How many of our original x particles have made the trip to the system? Let’s see, the particles now occupy a space of :

<p align=“center”> [sup]4[/sup]/[sub]3[/sub];<FONT FACE=“Symbol”>p</FONT> * 10[sup]3rd[/sup] cubic light years.
Or:
8.409 * 10[sup]41st[/sup] cubic kilometers.</p>

In addition, they are now at the very least 100 million years old, and their original numbers reduced by .5 to the tenth, or our original 10[sup]2[/sup]x is now 10[sup]-2[/sup]x viable seed specks.

With a three billion kilometer radius for the planetary portion of the system, neglecting the fact that only the ecliptic really matters, that leaves us with 1.34 * 10[sup]-15th[/sup]x viable particles in the system, but still not landed on a planet.

h=the chances of a unit landing and distributing itself throughout a suitable planet through reproduction once it was captured by a suitable system.

For any individual particle the chances are very small, and our arithmetic thus far has been based on normal random effects. In addition the sun, and the gas giant planets will attract the greater proportion of any such infalling material, leaving it vaporized, or buried beneath its crushing gravity, from which the chance of being expelled is near zero. Either way, it is out of the panspermia busness. This is another one where we have only the wildest of guesses, but the Earth represents only a tenth of a percent of the mass of the system not including the Sun. The entire Planetary system (including all planets, astroids, moons, and known comets) represents only tenth of a percent of the mass of the Sun. So, of whatever percent of the specks are ever captured, one in a million will land on Earth.

Many orders of magnitude less than 1.34 *10[sup]-21st[/sup]x viable particles impact with a particular target planet, our one in ten. We will use that number, confident that it represents a very generous estimate.

You forgot to mention the mortality rate for objects landing from orbit. I don’t deny it is possible to survive, but how many more negative exponents are we going to have to add to represent the miniscule chances of surviving re-entry? Let’s continue to be kind and call it a one in a million chance.

1.34 * 10[sup]-27th[/sup]x viable particles

I=How long H takes.

Hold on, lets solve for x.

If we want (f of x) to be equal to one when we finally get here, then x has to be equal to at least 1.34 * 10[sup]27th[/sup] viable particles. These little specks do not represent how many bits of ejecta we must have from each Dino buster, but rather the small proportion of that ejecta which has surviving bacteria after the original dino killer impact. If the average size of these bits is more than a milligram, that means that 1.34 * 10[sup]21st[/sup] Kg of life bearing matter has to survive each of the original explosions.

Now, How big was the portion of the ejecta that didn’t survive? By the way, the mass of the entire Earth is 6.0 * 10[sup]24th[/sup] Kg.
<P ALIGN=“CENTER”>Tris</P>

Before the beginning of great brilliance, there must be chaos. Before a brilliant person begins something great, they must look foolish in the crowd.
–I Ching

74

I think soving for A is an excellent idea.

I have received permission to post the reply from The Richfields (but it’s on my work computer, so I can’t do it until Monday)
Oddly enough they confirmed the 250 million year old bacteria revival from Permian salts, as occuring from material recovered from Mexican salt mines, so I guess Zubrin wasn’t wrong after all.

Also supplied is additional information which may go into deciding some of our variables. I’ll post the whole thing Monday.

My ideas are currently being studied by experts at Cambridge… …SO THERE!!!

75

Dr. Fidelius wrote:

Only if you start your journey from the surface of the sun.

If you start out as far away as the Earth is from the sun, solar escape velocity calculates out to be only 45 kilometers per second.

And if you start out on an Earth that’s already orbiting the sun at 30 km/s, you only need to add 15 km/s of delta-v in the same direction the Earth is going to reach solar escape velocity. (Actually, you’ll need to add about 16 km/s, since you lose a little speed overcoming the Earth’s gravity on your way out.) This is much easier to accomplish than the 600 km/s figure quoted above.

The truth, as always, is more complicated than that.

76

Fillet wrote:

Because evolution isn’t “progress.”

Most life forms on Earth are still single-celled bacteria. We multicellular eukaryotes make up a tiny little niche of terrestrial life’s huge diorama. Multicellular organisms only seem important because we humans happen to be multicellular organisms, and we like to think of ourselves as more significant than creepy little bugs.

As Stephen J. Gould said in his book Full House, we are not now living in the Age of Man, nor even in the Age of Mammals. We are now, and always have been, in the Age of Bacteria. (Well, okay, we have almost always been in the age of bacteria. Current findings suggest that before bacteria evolved, life on Earth consisted of free-floating self-replicating bits of RNA. But that’s close enough for hamburgers.)

The truth, as always, is more complicated than that.

77

Tracer wrote:

I realize full well that we are surrounded by various forms of single-celled life that are as fully evolved as we are, each for our own particular environment. I think you misunderstood my statement as “metazoan-centric” because I couched the question in informal terms.

It is still true, however, that the question of why such a long period of time elapsed before the first multicellular life appeared on this world is a key question for paleobiologists. Did it require the development of special biological regulatory functions? Was it linked to environmental conditions somehow (e.g., the level of atmospheric oxygen)? Understanding how and why major changes take place in living organisms, single-celled or not, has down-the-road implications in all sorts of fields, from medicine to environmental science to industry. Since we also deal with quite a lot of other multicellular organisms in our day-to-day lives (animals and plants both), it behooves us to devote a little attention to the subject.

Uh, last time I checked there were a lot more multicellular organisms around besides humans, and all have an important role to play in how this biosphere functions.

Now, that’s not to say that humans don’t have any biases in determining which subjects they’ll focus on. But that’s mostly because human taxpayers foot the bill for a lot of basic research, and they want to know how that research pertains to them. When the prokaryotes cough up some bucks, the human lay public would be happy to devote more resources to studies of single-celled organisms. :wink:

Strictly speaking, we can’t know that; S.J. has made a simplification in order to make a point (as I did in the post you quoted). The distinction between prokaryotes in the kingdoms Archaea and Bacteria is made through RNA analysis, which we can’t do on fossilized specimens (because the fossilization process completely replaces organic material). Molecular phylogenies suggest, though, that both lineages have been around for a very long time; and given Archaea’s ability to survive in all sorts of extreme environments as well as moderate ones, who’s to say that we haven’t been living in “the Age of Archaea”? :slight_smile: I think S.J. was simply trying to make the point that the microbial world is equally important.

78

Yep. And it may have all sorts of implications down the road for us.

But for a first guess as to why it took 2.5 billion years to go from the first signs of life on Earth to multicellular organisms, I do notice three things:

(1) The first geochemical signs of biological activity, a mere 300 million years after the Earth’s crust cooled, might not have been caused by full-blown bacteria. They may have been caused by much simpler organisms – such as free-floating ribosomes, or those little bacteria-esque critters that use RNA exclusively for all their genetic material and have no DNA (thereby having no need for the complexities of DNA-to-RNA transcription). It may have taken much longer than those first 300 million years for DNA-wielding bacteria to hit the scene and take over.

(2) The Oxygen Holocaust wiped out nearly all anaerobic life on Earth, and as you’ve mentioned, single-celled organisms are pretty lousy at leaving fossils behind for us to find. For all we know, some colony-living anaerobic bacteria might have achieved true multicellular organism status before they were annihilated. And

(3) There is not a single multicellular species on the planet that is not composed of eukaryotic cells. Eukaryotes are far more complex than bacteria, even if you don’t count the eukaryotes’ symbiotic organelles (mitochondria and chloroplasts). Many, many contingent stages of evolution had to happen on the semi-random-walk from bacteria to eukaryotes: They had to lose their cell wall, then grow much bigger, then use their size and motility to eat other cells, then their cell membrane had to wrap itself around the DNA, then this DNA-wrapping membrane section had to pinch off from the rest of the cell to form a nucleus while still allowing the cell-division machinery to work, then the DNA had to reshape itself into full-blown chromosome pairs … WHEW! That’d take me a couple billion years to accomplish, too!

The truth, as always, is more complicated than that.

79

Here’s the reply I received:

quote:

This is my first reaction to your notes. I’ll send a copy of this
correspondence to Benny in case he finds your idea of inverse
Panspermia sufficiently intriguing to show the rest of the folk.

HE WILL NOT DO SO WITHOUT YOUR PERMISSION.

(Benny, I have had a couple of private replies to the essay and I do not
know which the list members will find interesting. This is one of
them.)

After all AL, the point of these discussions is to share ideas. Let us
know asap whether that is OK by you and if so, you can send him your
rebuttals of any points of mine that you think are unsound.

If Benny does not see this going anywhere useful, OK, we need not bother
about polishing up our product for our waiting public, but can simply
slog ourselves to a standstill in private. On the other hand, if Benny
likes it, we could produce a shared document to summarise our respective
views in the light of each other’s reactions. Then stand back and watch
developments. :slight_smile:

Cheers,

Jon

===================================
>
> I am currently engaged in a discussion on an interesting twist in the
> controversial Panspermia hype.
>
> That is, the likelihood that Panspermic mechanisms have been occuring
for the past several billion years with Earth as the focus radiating
biological material outward.<

>The sun is basically radiating material away from
the solar system.<

Arguable. I would like to see figures demonstrating that there is a net
loss, instead of a net gain of infalling rock etc. This objection is
not serious though; I suspect that it is mainly the small particles that
are relevant to your argument. I grant that very small, light particles
such as protons generally have their walking shoes on. What happens
beyond heliopause, I am not so sure.

Mind you, if you expect the sun’s radiation to accelerate largeish
objects out of the solar system, then pardon my sniggers!

>If a fortuitous bacterial spore were able to catch a gravity assist from a nearby massive object, they could go even faster.<

Hmp. Same for a big object, up to asteroidal size at least.
Academically it applies to every planet up to Saturn!. Have you
calculated how many trajectories offer an acceleration that contributes
to escape velocity from the solar system? I bet they are a small
fraction of the ones that don’t do too much or simply swallow the
traveller or drop it into the sun.

>In support of this contention I cite: Carl Sagan Intelligent Life in the universe, Seth Shostak Sharing The Universe, and RH Zubrin and D. Andrews “Magnetic Sails and Interplanetary Travel” Journal of Spacecraft and Rockets April 1991<

Oh, the PRINCIPLE is fine; it is the resultant frequency of assistance
that leaves me a bit mumchance.

>But let’s use your figure of 600km/sec.<

MINE? I begin to suspect that I have a predecessor! Well, let’s accept
her figure for now.

>That takes 26,777 years for a bacterial spore to cover a light year. We know that spores can survive for 250 million years (maybe more), and provide viable cultures. Let’s call this the upper limit.<

Let’s? Well, I’m not so sure it isn’t over-generous as upper limits
go. Just what spores are these 250MY jobs? Amber fossils? IF this is
correct, and I have my severe doubts, then remember that you are talking
about some very special conditions and pretty gentle handling. I should
like some good documentation to convince me firstly that that is at all
a realistic figure, and if so, for how many spores (note that most
microbes do NOT form spores anyway.) If we get one survivor out of a
billion starters, and then only in a good, rich medium then the
implications begin to look a good deal less optimistic!

> That means a bacterial spore can travel 9,000 or so light years and remain viable.<

Not unless the putative 250MY-old spores were stored in similar
conditions to your 250MY relics, it doesn’t! Most bacteria I know
would not survive attaining solar system escape velocity at all, and
most of the more resistant ones would probably not survive the voyage
past Pluto.

>It’s estimated that the milky way galaxy contains 300 billion stars, and it rotates about once every 250 million years. It’s 103,000 light years in diameter. That gives us 8.3 million square light years as the size of the galaxy through the plane of the ecliptic. It’s also about 5-10,000 light years thick. Take 7.5 as average. That gives us an average stellar denstity of about 1 star every two light years. <

Watch it! The average stellar density is one thing. The average
stellar density in our 9000LY (grossly optimistic) radius is a lot
lower. We are far from the galactic core, remember! Maybe a lot less
that one star per four light years and in any case, what sort of density
measurement is that? Stars per light year? Stars per steradian I could
consider; Stellar cross section in steradians per space steradian, fine!
Capture cross section in steradians per space steradian, great! Stars
per cubic LY perhaps, but stars per light year? Would you care to
re-define that calibration?

>You cannot draw a line across the plane of the galactic ecliptic for 9,000 light years without encountering another star.<

I bloody sure can! Whole galaxies interpenetrate with barely a stellar
collision. Even taking your 1/2LY, and sticking to your linear measures
of volume, that is less than 1ppm of star. More soundly it is less than
1e-12 in terms of cross section. (Check my thumbsucks someone!) Your
9000LY would hardly get us even into a dense stellar field anyway, and
besides, what is all this ecliptic stuff? What portion of available
trajectories count as being in the plane of the ecliptic? 1%? 0.01%?

> In fact each bacterial spore traveling across the plane of the ecliptic should have the oportunity to pass within 1/2 light year of 1,000 different stars while it is still viable, and possibly be captured by one of those systems.<

Now hold it right there! Suddenly a 0.5LY radius defines a capture
cross section? Says who? Suppose my spore does get there at 600kps, why
does it suddenly start navigating to the nearest hospitable planet? Why
does it not simply continue past in hyperbolic orbit, possibly picking
up some slingshot benefit on the way? Or just smash into the biggest
target around, stoking up the new sun to greater brightness and starting
a colony right there?

>One out of ten stars is a type g or k, similar to our sun.
That’s 100 possible candidates.
Let’s arbitrarily decide that 1 out of ten suns is a solar system
similar to ours, with small warm inner planets (best data right now says
the odds are better than this.)<

Glad to hear you say so. I was just getting depressed. And why so
modest? We are after all just interested in panspermia, not only
technological civilisations. You could go all the way down to class m
stars comfortably and expect those really tough spores of yours to
manage the climate. Who knows, a sufficiently dark brown dwarf might be
directly colonisable without any planets at all.

>That’s ten possible candidates, or a 1 in one hundred chance for a given bacteria to end up in a viable solar system.<

Ahem… You know, I’m so gullible that I’d make a lousy auditor, but
this is a bit much! You would be doing pretty nicely to get a one in a
billion chance! As for winding up in a viable form in a viable place in
such a system, shall we talk trillions? And those are thumbsucks. I
don’t have the nerve to work out anything plausible, and wouldn’t DREAM
of running my figures past a hard-nosed astronomer.

>Let’s be arbitrary and say that only one in a million of these will ever find itself intact in a suitable place on a viable planet.<

Too arbitrary for me by perhaps twelve orders of magnitude! You’ll have
to tidy up your figu

80

Scylla

You don’t seem to have much to say about my analysis of your proposed likelyhood of seeding the galaxy from Earth. Let me make a simpler problem out of it. How much material would it take to put ** one kilogram ** of material in each solar system sized sphere in a radius of 10 light years of Earth? We won’t consider any other factor than volume, and mass.

The radius of the solar system is about 30 AU. An AU is about eight light minutes, so our solar system’s entire volume is:
<P ALIGN=“CENTER”>V[sub]s[/sub] = [sup]4[/sup]/[sub]3 [/sub] <FONT FACE=“Symbol”>p</FONT> * (80 *299,792,458)³
Or, 5.779 * 10[sup]31[/sup]cubic meters
While the volume of the broadcast sphere ten light years radius is:
<P ALIGN=“CENTER”>V[sub]b[/sub][sup]4[/sup]/[sub]3 </sub?> <FONT FACE=“Symbol”>p</FONT> * (31,484,550 * 299,792,458 )³
Or, 3.522 * 10[sup]48[/sup]cubic meters
For each kilogram per solar system volume over the sphere, one must have a total mass (M) equal to the mass in each solar system, times the ratio of the two volumes, or:
P ALIGN=“CENTER”>M = V[sub]b[/sub] ÷ V[sub]s[/sub]
M = 3.522 * 10[sup]48[/sup] ÷ 5.779 * 10[sup]31[/sup]
M = 6.09 * 10 [sup]16[/sup] kilograms
Earth’s mass is 5.98 x 10[sup]24[/sup] kilograms. Only one ten millionth of the mass of the Earth is used up to put each kilogram of seed material into all (or should I say both) of the systems within ten light years. How many kilograms do you want wandering around in the 60,000,000,000,000,000,000,000 cubic kilometers of space that represents our bullseye?

And what about the more realistic volume of 1000 light years? That only takes a tenth of the Earth’s mass, for each kilogram. The whole galaxy? My calculator only does 10[sup]999[/sup] notation.

<P ALIGN=“CENTER”>Tris</P>

“Can you do addition?” the White Queen asked. “What’s one and one and one and one and one and one and one and one and one and one?” “I don’t know,” said Alice. “I lost count.” – Lewis Carroll, Through the Looking Glass